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FAUSTO FANTINI

COMPONENTE ORGANI COLLEGIALI presso: Direzione Pianificazione, Valutazione e Servizi Informatici Applicativi


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Pubblicazioni

2016 - Correlation between dynamic Rdson transients and Carbon related buffer traps in AlGaN/GaN HEMTs [Relazione in Atti di Convegno]
Iucolano, F.; Parisi, A.; Reina, S.; Patti, A.; Coffa, S.; Meneghesso, G.; Verzellesi, Giovanni; Fantini, Fausto; Chini, Alessandro
abstract

The on resistance increment observed when the device is operated at high drain-source voltages is one the topics that limits the performance of the AlGaN/GaN HEMT devices. In this paper, the physical mechanisms responsible of the RDSon degradation are investigated. The dynamic RDSon transient method is used in order to get insight to characterize the traps states. By calculating the Arrhenius plot associated with the RDSon transients an activation energy of 0.86eV was extracted, that can be correlated to the traps due to the incorporation of Carbon inside the buffer. This hypothesis was further supported by the analyses performed on a simpler structure (TLM). By applying a negative substrate bias the effect of only the buffer traps was studied. A fairly close value of the activation energy (0.9eV) to the one extracted when analyzing the RDSon transient was obtained.


2016 - Experimental and Numerical Analysis of Hole Emission Process from Carbon-Related Traps in GaN Buffer Layers [Articolo su rivista]
CHINI, Alessandro; Meneghesso, G.; Meneghini, M.; FANTINI, Fausto; VERZELLESI, Giovanni; Patti, A.; Iucolano, F.
abstract

The role of carbon-related traps in GaN-based ungated high-electron mobility transistor structures has been investigated both experimentally and by means of numerical simulations. A clear quantitative correlation between the experimental data and numerical simulations has been obtained. The observed current decrease in the tested structure during backgating measurements has been explained simply by means of a thermally activated hole-emission process with E-A = 0.9eV, corresponding to the distance of the acceptor-like hole-Trap level from the GaN valence band. Moreover, it has been demonstrated by means of electrical measurements and numerical simulations that only a low percentage of the nominal carbon doping levels induces the observed current reduction when negative substrate bias is applied to the tested structure.


2013 - Impact of field-plate geometry on the reliability of GaN-on-SiC HEMTs [Articolo su rivista]
Chini, Alessandro; Soci, Fabio; Fantini, Fausto; Nanni, A.; Pantellini, A.; Lanzieri, C.; Meneghesso, G.; Zanoni, E.
abstract

GaN on SiC HEMTs fabricated with different gate-connected field plate structures have been tested by means of RF reliability tests. The increase in field-plate length yielded an improvement of both the dynamic and the reliability performance during RF testing. Results are thus suggesting that reliability in field-plate devices can be improved by a proper design of the field-plate geometry.


2012 - Analysis of GaN HEMT Failure Mechanisms During DC and Large-Signal RF Operation [Articolo su rivista]
Chini, Alessandro; DI LECCE, Valerio; Fantini, Fausto; Meneghesso, G.; Zanoni, E.
abstract

An analysis of the reliability of GaN high-electron-mobility transistors during dc and RF stress tests is presented. Competing degradation mechanisms have been observed during RF operation, demonstrating the dependence of device reliability on device RF driving conditions. DC tests revealed only one degradation pattern related to defect formation at the high-electric-field region of the gate contact. RF signals, however, allow for other physical phenomena to take place before the said defect formation. Electron injection on the gate–drain region decreases the electric field value, thus counteracting the electric-field-induced defect formation at the gate edge.


2012 - Field plate related reliability improvements in GaN-on-Si HEMTs [Articolo su rivista]
Chini, Alessandro; Soci, Fabio; Fantini, Fausto; Nanni, A.; Pantellini, A.; Lanzieri, C.; Bisi, D.; Meneghesso, G.; Zanoni, E.
abstract

State of the art GaN on Silicon HEMTs fabricated with and without a field-plate structure have been tested by means of DC and RF reliability tests. The introduction of the field-plate structure greatly improves device reliability both during DC as well as RF testing. Results are thus suggesting that reliability in NOFP and FP devices is mainly limited by the high electric fields within the device structure causing an increase in traps concentration.


2011 - An Investigation of the Electrical Degradation of GaN High-Electron-Mobility Transistors by Numerical Simulations of DC Characteristics and Scattering Parameters [Articolo su rivista]
DI LECCE, Valerio; Esposto, Michele; Bonaiuti, Matteo; Fantini, Fausto; Meneghesso, G.; Zanoni, E.; Chini, Alessandro
abstract

The effects of direct-current (DC) stress on GaN high-electron-mobility transistors (HEMTs) are investigated by means of numerical simulations, by which the creation of an acceptor trap in the AlGaN barrier layer was correlated to the observed experimental degradation. An increase in the trap concentration induces a worsening of the saturated current IDSS, transconductance g m, and output conductance gO. An increase in the length of the trapping region induces a degradation of IDSS and gm, but can reduce gO. Analysis of scattering parameters in the saturation region shows that the cutoff frequency fT matches the trend of gm.


2011 - Improvement of breakdown and DC-to-pulse dispersion properties in field-plated InGaAs-InAlAs pHEMTs [Relazione in Atti di Convegno]
Saguatti, Davide; M., Mohamad Isa; K. W., Ian; Chini, Alessandro; Verzellesi, Giovanni; Fantini, Fausto; M., Missous
abstract

We report on novel, high voltage InGaAs-InAlAs pHEMTs, which have been processed on an optimized epilayer and incorporate field-plate structures of different dimensions. Fabricated devices demonstrate great improvements in break-down voltage and gate leakage, while keeping the same DC and RF behaviour with respect to baseline devices, i.e. with no field-plate implemented. In addition, the field plate strongly attenuates DC-to-pulse dispersion, making these devices suitable for high-power-density RF power amplifiers.


2010 - Analysis of current collapse effect in AlGaN/GaN HEMT: experiments and numerical simulations [Articolo su rivista]
M., Faqir; M., Bouya; N., Malbert; N., Labat; D., Carisetti; B., Lambert; Verzellesi, Giovanni; Fantini, Fausto
abstract

In this work, current collapse effects in AlGaN/GaN HEMTs are investigated by means of measurements and two-dimensional physical simulations. According to pulsed measurements, the used devices exhibit a significant gate-lag and a less pronounced drain-lag ascribed to the presence of surface/barrier and buffer traps, respectively. As a matter of fact, two trap levels (0.45 eV and 0.78 eV) were extracted by trapping analysis based on isothermal current transient. On the other hand, 2D physical simulations suggest that the kink effect can be explained by electron trapping into barrier traps and a consequent electron emission after a certain electric-field is reached.


2010 - Experimental and simulated dc degradation of GaN HEMTs by means of gate-drain and gate-source reverse bias stress [Articolo su rivista]
DI LECCE, Valerio; Esposto, Michele; Bonaiuti, Matteo; Meneghesso, G.; Zanoni, E.; Fantini, Fausto; Chini, Alessandro
abstract

In this paper, the degradation of AlGaN/GaN high-electron mobility transistors (HEMTs) is investigated by means of dc stresses performed on fresh devices either on the gate-drain junction only (i.e., with the source terminal floating) or on the gate-source junction only (i.e., with the drain terminal floating). In both cases step-stresses were carried out by increasing VDG and VSG respectively up to 35 V: the saturated drain current decreased in both cases, and a significant increase in the output conductance was found for the drain-stressed devices, whereas it was negligible for the source-stressed devices. The reason for these different behaviors was believed to be the creation of acceptor traps in the AlGaN layer underneath the stressed side of the gate junction, their influence being different in the two cases because of the high horizontal electric field at the drain end of the gate during on-state operation. We carried out numerical simulations showing that the presence of a defective region with an acceptor trap concentration underneath the gate-drain or gate-source junction fits our hypothesis.


2010 - Study of GaN HEMTs degradation by numerical simulations of scattering parameters [Abstract in Atti di Convegno]
DI LECCE, Valerio; Esposto, Michele; Bonaiuti, M.; Meneghesso, G.; Zanoni, E.; Fantini, Fausto; Chini, Alessandro
abstract

In this paper, a study of the dependence of the transconductance gm on the trap concentration and on the length of the trapping region is carried out by means of numerical simulations, and particular attention is dedicated to the correlation between gm and the device AC performance by simulation of scattering parameters.


2010 - Study of GaN HEMTs electrical degradation by means of numerical simulations [Relazione in Atti di Convegno]
DI LECCE, Valerio; Esposto, Michele; Bonaiuti, Matteo; Fantini, Fausto; Chini, Alessandro
abstract

In this paper, we investigate the effects of dc stress on GaN high-electron mobility transistors (HEMTs) by means of numerical simulations. Following stress tests showing a degradation of static characteristics (dc), the formation of an electron trap in the AlGaN barrier layer was related to the observed degradation according to the results obtained from numerical simulations carried out by introducing a trapping region underneath the gate edge. The worsening of the device dc performance is evaluated by changing the extension of the degraded region and the trap concentration while studying the variation of parameters like the saturated drain current IDSS, the output conductance g O, and the device transconductance gM. An increase in the trap concentration induces a worsening of any of the abovementioned parameters; an increase in the extension of the degraded region induces a degradation of IDSS and gM, but can reduce gO.


2009 - Correlation between DC and rf degradation due to deep levels in AlGaN/GaN HEMTs [Relazione in Atti di Convegno]
Chini, Alessandro; Fantini, Fausto; DI LECCE, Valerio; Esposto, Michele; Stocco, A.; Ronchi, N.; Zanon, F.; Meneghesso, G.; Zanoni, E.
abstract

We investigate the role of the 0.5 eV traps in determining GaN HEMT degradation by means of DC and rf testing, and 2D numerical simulation. We demonstrate that generation of deep levels, having an activation energy of 0.5 eV, is responsible for the degradation observed during rf aging; we show that the occurrence of trap-induced degradation depends on rf driving conditions. We also show that degradation can be explained by the generation of a damaged region within the AlGaN layer at the gate-drain edge, and that the DC and pulsed device degradation effects have a different dependence on the width and depth of the damaged region.


2009 - Design of field-plated InP-based HEMTs [Abstract in Atti di Convegno]
Saguatti, Davide; DI LECCE, Valerio; Esposto, Michele; Chini, Alessandro; Fantini, Fausto; Verzellesi, Giovanni; Boulay, S.; Bouloukou, A.; Boudjelida, B.; Missous, M.
abstract

The design of field-plated InP-based HEMTs is presented by means of numerical simulations tools aimed at the optimization of device breakdown voltages.


2009 - False surface-trap signatures induced by buffer traps in AlGaN-GaN HEMTs [Relazione in Atti di Convegno]
Verzellesi, Giovanni; Faqir, Mustapha; Chini, Alessandro; Fantini, Fausto; Meneghesso, G.; Zanoni, E.; Danesin, F.; Zanon, F.; Rampazzo, F.; Marino, F. A.; Cavallini, A.; Castaldini, A.
abstract

Buffer traps can induce “false” surface-trap signatures in AlGaN-GaN HEMTs, namely the same type of current-mode DLTS peaks and pulse responses that are generally attributed to surface traps. Device simulations are adopted to clarify the underlying physics. Being aware of the above phenomenon is important for both reliability testing and device optimization, as it can lead to erroneous identification of the degradation mechanism, thus resulting in inappropriate correction actions on the technological process.


2009 - Influence of interface states at Schottky junction on the large signal behaviour of Cu-gate standard AlGaN/GaN HEMTs [Abstract in Atti di Convegno]
Esposto, Michele; DI LECCE, Valerio; Bonaiuti, Matteo; Fantini, Fausto; Verzellesi, Giovanni; De Guido, S.; De Vittorio, M.; Passaseo, A.; Chini, Alessandro
abstract

Copper (Cu)-gate AlGaN/GaN High Electron Mobility Transistors have been already proposed by Ao et al. [5] and more recently by Sun et al. [6]. Gate leakage currents, Schottky barrier heights and other small signal parameters have found to be very interesting for Cu-gate devices. The aim of our work is to evaluate the large signal characteristics, giving a direct comparison between Cu-gate device and Ni/Au-gate one.


2009 - Influence of RF drive and switching frequency on degradation mechanisms in GaN HEMTs [Abstract in Atti di Convegno]
DI LECCE, Valerio; Esposto, Michele; Bonaiuti, Matteo; Fantini, Fausto; Chini, Alessandro; Meneghesso, G.; Zanoni, E.
abstract

GaN-based high-electron mobility transistors (HEMTs) have received increasing attention for their outstanding performance in RF-power applications [1]–[3]. Gallium nitride’s wide energy gap (3.49eV) and breakdown field (3MV/cm) allow HEMTs to tolerate high voltages and high temperatures, while its higher saturation velocity and the absence of doping atoms in the channel make them very fast switching devices compared to silicon-based ones. However, HEMTs still suffer from reliability problems like current collapse, gate-lag, and RF degradation, to be solved before they can be used for commercial purposes [4]–[5]. In this paper a review of RF and pseudo-RF stress campaigns carried out on GaN HEMTs is presented.


2008 - Effects of Surface and Buffer Traps in Passivated AlGaN-GaN HEMT [Abstract in Atti di Convegno]
Faqir, Mustapha; Verzellesi, Giovanni; Chini, Alessandro; Fantini, Fausto; Danesin, F.; Rampazzo, F.; Meneghesso, G.; Zanoni, E.; Labat, N.; Touboul, A.; Dua, C.
abstract

The effects of surface and buffer traps in passivated AlGaN-GaN HEMT on their pulsed I-V characteristics has been investigated by means of numerical simulations.


2008 - Effects of surface and buffer traps in passivated AlGaN/GaN HEMTs [Abstract in Atti di Convegno]
Faqir, Mustapha; Verzellesi, Giovanni; Chini, Alessandro; Fantini, Fausto; F., Danesin; F., Rampazzo; G., Meneghesso; E., Zanoni; N., Labat; A., Touboul; C., Dua
abstract

The physical mechanisms underlying RF current collapse effects in AlGaN-GaN HEMTs are investigated by means of measurements and numerical device simulations. Our study suggests that 1) both surface and buffer traps can contribute to RF current collapse through a similar physical mechanism involving capture/emission of electrons tunneling from the gate; 2) surface passivation strongly mitigate RF current collapse, by reducing the surface electric field and inhibiting electron injection into traps; 3) for surface donor trap densities lower than 9e12 /cm2, surface potential barriers in the 1-2 eV range can coexist with surface traps having much a shallower energy depth and inducing, therefore, current-collapse effects characterized by relatively short time constants.


2008 - Investigation of High-Electric-Field Degradation Effects in AlGaN/GaN HEMTs [Articolo su rivista]
Faqir, Mustapha; Verzellesi, Giovanni; G., Meneghesso; E., Zanoni; Fantini, Fausto
abstract

High-electric-field degradation phenomena are investigated in GaN-capped AlGaN-GaN HEMTs by comparing experimental data with numerical device simulations. 150-hour DC stresses were carried out under power-state and off-state conditions. Degradations effects characterizing both stress experiments were: a drop in the DC drain current, the amplification of gate-lag effects, and a decrease in the reverse gate leakage current. Numerical simulations indicate that the simultaneous generation of surface (and/or barrier) traps and of buffer traps can account for all of the above degradation modes. Experiments showed also that the power-state stress induced a drop in the transconductance at high gate-source voltages only, whereas the off-state stress led to a uniform transconductance drop over the entire gate-source-voltage range. This behavior can be reproduced by simulations provided that, under power-state stress, traps are assumed to accumulate over a wide region extending laterally from the gate edge towards the drain contact, whereas, under off-state stress, trap generation is supposed to take place in a narrower portion of the drain access region close to the gate edge and to be accompanied by a significant degradation of the channel transport parameters.


2008 - Mechanisms of RF Current Collapse in AlGaN–GaN High Electron Mobility Transistors [Articolo su rivista]
Faqir, Mustapha; Verzellesi, Giovanni; Chini, Alessandro; Fantini, Fausto; Danesin, F.; Meneghesso, G.; Zanoni, E.; Dua, C.
abstract

The physical mechanisms underlying RF current collapse effects in AlGaN-GaN HEMTs are investigated by means of measurements and numerical device simulations. Our study suggests that 1) both surface and buffer traps can contribute to RF current collapse through a similar physical mechanism involving capture and emission of electrons tunneling from the gate; 2) surface passivation strongly mitigates RF current collapse by reducing the surface electric field and inhibiting electron injection into traps; 3) for surface-trap densities lower than 9e12 cm-2, surface potential barriers in the 1-2 eV range can coexist with surface traps having much a shallower energy and therefore inducing RF current collapse effects characterized by relatively-short time constants.


2008 - Sulfur-contamination of high power white LED. [Articolo su rivista]
G., Mura; G., Cassanelli; Fantini, Fausto; M., Vanzi
abstract

Silver-sulfur compounds have been detected at the internal lead frame of several commercial plastic packaged white LEDs that passed a standard incoming lot inspection but resulted all electrically open or degraded at the switching-on after mounting on the final boards.


2007 - Analysis of High-Electric-Field Degradation in AlGaN/GaN HEMTs [Relazione in Atti di Convegno]
Faqir, Mustapha; Chini, Alessandro; Verzellesi, Giovanni; Fantini, Fausto; Rampazzo, F.; Meneghesso, G.; Zanoni, E.; Kordos, P.
abstract

High-electric-field degradation phenomena are investigated in GaN-capped AlGaN-GaN HEMTs by comparing experimental data with numerical device simulations. Simulations indicate that the stress-induced amplification of gate-lag effects and the correlated gate-leakage-current reduction can be ascribed to the generation of acceptor traps at the gate-drain surface and/or in the device barrier. The drop in DC drain current observed after stress should rather be attributed to trap accumulation within the GaN buffer region. Only the simultaneous generation of surface (and/or barrier) and buffer traps can account for all of the observed degradation modes. Simulations suggest also that under power-state stress traps should accumulate over a wide region extending laterally from the gate edge towards the drain contact, whereas, under off-state stress, trap generation should rather take place in a narrower portion of the drain access region close to the gate edge and should be accompanied by a significant degradation of the channel transport parameters. Channel hot electrons and electric-field-induced strain-enhancement are finally suggested to play major roles in power-state and off-state degradation, respectively.


2007 - Characterization and analysis of trap-related effects in AlGaN/GaN HEMTs [Articolo su rivista]
Faqir, Mustapha; Verzellesi, Giovanni; Fantini, Fausto; F., Danesin; F., Rampazzo; G., Meneghesso; E., Zanoni; A., Cavallini; A., Castaldini; N., Labat; A., Touboul; C., Dua
abstract

Traps are characterized in AlGaN-GaN HEMTs by means of DLTS techniques and the associated charge/discharge behavior is interpreted with the aid of numerical device simulations. Under specific bias conditions, buffer traps can produce “false” surface-trap signals, i.e. the same type of current-mode DLTS (I-DLTS) or ICTS signals that are generally attributed to surface traps. Clarifying this aspect is important for both reliability testing and device optimization, as it can lead to erroneous identification of the degradation mechanism, thus resulting in wrong correction actions on the technological process.


2007 - Interpretation of buffer-trap effects in AlGaN/GaN HEMTs [Abstract in Atti di Convegno]
Faqir, Mustapha; Verzellesi, Giovanni; Fantini, Fausto; A., Cavallini; A., Castaldini; F., Danesin; G., Meneghesso; E., Zanoni
abstract

Traps are identified in AlGaN-GaN HEMTs by means of different characterization techniques and the associated physical behavior is interpreted with the aid of numerical device simulations. It is in particular been shown that, under specific bias conditions, buffer traps can produce the same type of current-mode DLTS (I-DLTS), ICTS, and gm-dispersion signals that are generally attributed to surface traps. Clarifying this fact is crucial for both reliability testing and device optimization, as it can completely hinder a correct identification of degradation mechanisms.


2006 - A Single-Chip 5GHz WLAN Transmitter in 0.35um Si/SiGe BiCMOS Technology [Relazione in Atti di Convegno]
F., Alimenti; Borgarino, Mattia; R., Codeluppi; V., Palazzari; M., Pifferi; L., Roselli; A., Scorzoni; Fantini, Fausto
abstract

The paper deals with the design of a 5GHz WLAN heterodyne transmitter for domotic applications. The transmitter has been realized in commercial 0.35mum Si/SiGe BiCMOS technology with the purpose to reduce cost while achieve an high integration level. Measurements on a prototype, wire-bonded on a low-cost FR4 printed circuit board, have been carried-out showing an overall linear gain of 14dB an input referred compression point of -6.5dBm and a third-order input intercept point of +2.7dBm


2006 - Bias Dependent, Compact Low-Frequency Noise Model of GaInP/GaAs HBT: Experimental Identification and CAD Implementation [Relazione in Atti di Convegno]
Borgarino, Mattia; N., Corciulo; C., Florian; P. A., Traverso; Fantini, Fausto; F., Filicori
abstract

In the present paper, the experimental identification of a compact low-frequency noise model of GaInP/GaAs Heterojunction Bipolar Transistors and its implementation in a widely employed RF CAD software is described. The model is analytical so that its CAD implementation does not require look-up tables. In addition to the usual control of the noise sources through the DC or the mean value of the base current, the model reported in the present work is flexible enough to allows for the control of the noise sources through the instantaneous value of the base current.


2006 - Failure Analysis-assisted FMEA [Articolo su rivista]
Cassanelli, Giulia; G., Mura; Fantini, Fausto; M., Vanzi; B., Plano
abstract

In this paper, ordinary FMEA (Failure Mode and Effects Analysis) was applied during the design phase of an electric motor control system for vehicle HVAC (HeatingNentilation/Air Conditioning). The analysis of the field data from the second year forces to review FMEA. The corrective actions, planned on the basis of the sole failure mode, as usual in FMEA, proved to be inadequate and Failure Analysis was performed to understand the failure mechanism of the indicted component and integrate. New proper corrective actions were devised and successfully implemented.


2006 - Physical investigation of high-field degradation mechanisms in GaN/AlGaN/GaN hemts [Relazione in Atti di Convegno]
Faqir, Mustapha; Chini, Alessandro; Verzellesi, Giovanni; Fantini, Fausto; Rampazzo, F.; Meneghesso, G.; Zanoni, E.; Bernat, J.; Kordos, P.
abstract

High-electric-field degradation phenomena are investigated in GaN-capped AlGaN-GaN HEMTs by comparing experimental data with numerical device simulations. Simulations indicate that the stress-induced amplification of gate-lag effects and the correlated gate-leakage-current reduction can be ascribed to the generation of acceptor traps at the gate-drain surface. The drop in DC drain current observed after stress should rather be attributed to trap accumulation within the GaN buffer region. Only the simultaneous generation of surface and buffer traps can account for all of the observed degradation modes. © 2006 JEDEC.


2006 - Study of high-field degradation phenomena in GaN-capped AlGaN/GaN HEMTs [Abstract in Atti di Convegno]
Faqir, Mustapha; Chini, Alessandro; Verzellesi, Giovanni; Fantini, Fausto; Rampazzo, F.; Meneghesso, G.; Zanoni, E.; Bernat, J.; Kordos, P.
abstract

High-electric-field degradation phenomena are studied in GaN-capped AlGaN-GaN HEMTs by comparing experimental results with numerical device simulations and assessing the suitability of different degradation scenarios to account for the observed electrical stress effects.


2006 - The rule of the Rue Morgue: a decade later [Relazione in Atti di Convegno]
G., Mura; M., Vanzi; G., Cassanelli; Fantini, Fausto
abstract

The paper could limit itself to repeat the complaint that originated the first "Rules of the Rue Morgue", maybe updating the scenario of the many end users currently exposed to the risk of failed failure analyses. Nevertheless, some constructive proposals will be also pointed out, as those exposed by a recent paper (Cassanelli et al., 2005) that, dealing with the challenges in system reliability predictions, proposed some shortcuts to include even few field data into that process, and to include F.A. findings, when reliable, to skip cumbersome (and often not available) extraction of reliability parameters by statistical data. More specifically, in both the reported B and C cases the sudden occurrence of the failure mode was not related to any sudden firing of the root failure mechanisms, but other hidden roots have been identified, with completely different corrective actions with respect to the first interpretations. There is a simple and "correct" conclusion to this result: by means of thorough analyses, the first specimen (IGBT) was indicted for some higher sensitivity to latch-up, and the second (CMOS) to external EMI-induced ESD events. This could move to correct the corresponding pi factors employed for calculating the actual failure rate lambda drawing a physically sound shortcut to the estimation of the reliability parameters for some critical devices of a given electronic system


2005 - Design of RFIC's in 0.35um Si/SiGe BiCMOS Technology for a 5GHz Domotic Transmitter [Relazione in Atti di Convegno]
F., Alimenti; Borgarino, Mattia; R., Codeluppi; V., Palazzari; Pifferi, Marco; L., Roselli; A., Scorzoni; Fantini, Fausto
abstract

The work deals with the basic building blocks of a 5GHz WLAN transmitter for domotic applications. These building blocks have been designed exploiting a commercial 0.35um Si/SiGe BiCMOS technology with the purpose to avoid the necessity of external components. On-wafer measurements have been carried-out on the realized prototypes showing a good agreement with simulatedperformances.


2005 - Low Noise, Low Interference Automated Bias Networks for Low Frequency Noise Characterization Set-Up's [Relazione in Atti di Convegno]
Borgarino, Mattia; M., Rossi; Fantini, Fausto
abstract

The work reports on the implementation of electromechanical bias networks to be employed in an automated experimental set-up for the low frequency noise characterization of bipolar transistors. The obtained bias networks allowed to improve theautomatization degree of the experimental set-up, reducingtherefore the time and the efforts for the systematic characterization necessary for the identification of nonlinearlow frequency noise models. The electromechanical bias networks were successfully applied to the systematic characterization at wafer level of microwave GaInP/GaAs heterojunction bipolar transistors.


2005 - Reliability predictions in electronic industrial applications [Articolo su rivista]
G., Cassanelli; G., Mura; F., Cesaretti; M., Vanzi; Fantini, Fausto
abstract

The paper describes a reliability prediction methodology that may be used to evaluate the reliability of electronics systems for industrial applications. The proposed methodology takes advantage of the potentiality of different reliability approaches. The aim of this new methodology is to minimize the deficiencies of the traditional reliability prediction methods calculating a corrective factor using the available field return data. In this way is possible to realize more realistic reliability assessment also in the case of new products or products without historic data. Applications of this prediction methodology on real electronic industrial systems are presented.


2004 - Biased resistor network model for electromigration failure and related phenomena in metallic lines [Articolo su rivista]
Pennetta, C; Alfinito, E; Reggiani, L; Fantini, Fausto; Demunari, I; Scorzoni, A.
abstract

Electromigration phenomena in metallic lines are studied by using a biased resistor network model. The void formation induced by the electron wind is simulated by a stochastic process of resistor breaking, while the growth of mechanical stress inside the line is described by an antagonist process of recovery of the broken resistors. The model accounts for the existence of temperature gradients due to current crowding and Joule heating. Alloying effects are also accounted for. Monte Carlo simulations allow the study within a unified theoretical framework of a variety of relevant features related to the electromigration. The predictions of the model are in excellent agreement with the experiments and in particular with the degradation towards electrical breakdown of stressed Al-Cu thin metallic lines. Detailed investigations refer to the damage pattern, the distribution of the times to failure (TTFs), the generalized Black's law, the time evolution of the resistance, including the early-stage change due to alloying effects and the electromigration saturation appearing at low current densities or for short line lengths. The dependence of the TTFs on the length and width of the metallic line is also well reproduced. Finally, the model successfully describes the resistance noise properties under steady state conditions.


2004 - Failure analysis of RuO2 thick film chip resistors [Articolo su rivista]
S., Podda; G., Cassanelli; Fantini, Fausto; M., Vanzi
abstract

This work presents the results of Failure Analysis carried out on RuO2 Thick Film Chip Resistors in field failed. Microscopical investigation performed on virgin, degraded and open circuit devices showed the failure mechanism involved: evidence for mechanical cracks may be related with the observed degradation and failures. On the failed and degraded devices some bad adhesion of the resistive film on the metallized alumina has been observed, which also could be consistent with thermomechanical hypothesis for the failure mechanism.


2004 - Semi-Automated Experimental Set-Up CAD-oriented Low Frequency Noise Modeling of Bipolar Transistors [Relazione in Atti di Convegno]
Borgarino, Mattia; A., Bogoni; Fantini, Fausto; M., Peroni; C. A., Cetronio
abstract

The present work addresses the hardware and software development of a semi-automated experimental set-up devoted to the extraction of low frequency noise compact models of bipolar transistors for microwave circuit applications (e.g. oscillators). The obtained experimental setup is applied to GaInP/GaAs Heterojunction Bipolar Transistors.


2003 - High electric field induced degradation of the DC characteristics in Si/SiGe HEMT's [Articolo su rivista]
J., Kuchenbecker; Borgarino, Mattia; M., Zeuner; U., Konig; R., Plana; Fantini, Fausto
abstract

We report, for the first time, results on the reliability of Si/SiGe HEMT´s. The present work addresses the high electric field stress effects on the DC characteristics. In particular, we report the variations of the output characteristics (drain and gate current), of the transconductance, of the threshold voltage, and of the breakdown voltage. Subsequently, possible degradation mechanisms are presented. The observed variations are discussed in comparison with similar experiments carried out on PHEMT´s issued of the III-V technology. Keywords: HEMT´s, Reliability, SiGe, DC Characteristics


2003 - Principi di Qualità [Monografia/Trattato scientifico]
Fantini, Fausto; L., Cattani
abstract

Il testo contiene i principi base relativi alla qualità, con particolare attenzione alle norme della famiglia ISO 9000 e al miglioramento.


2003 - Reliability in automotive electronics: a case study applied to diesel engine control [Articolo su rivista]
G., Cassanelli; Fantini, Fausto; G., Serra; S., Sgatti
abstract

In this paper the problem of the reliability in automotive electronics, applied to the case of diesel engine control, in particularly to the Multijet ECU, is discussed. The aim of this paper is to define methodologies to estimate, to control and to improve reliability in automotive field. The functionality and the complexity of automotive electronic systems are rapidly growing and lead to increased networking, higher degrees of integration, and mechatronic solutions. Some electronic parts are placed under the hood or on the combustion engine or inside the gearbox, where environmental conditions are really harsh in terms of temperature, vibrations and shocks. Consequently, specific approaches in order to assure a high reliability level have been developed. In the first section of the paper the Multijet system is described, then a reliability analysis of the system using the reliability tool FMEA (Failure Modes and Effects Analysis) and FTA (Fault Tree Analysis) is presented. Eventually, the injector control subsystem is describes and its reliability analysis is presented. In the last part we try to find some links between the two different levels of abstraction in the reliability analysis.


2003 - Simulation of electromigrationphenomena and associated resistance noise in Al-Cu metallic lines [Relazione in Atti di Convegno]
E., Alfinito; C., Pennetta; L., Reggiani; Fantini, Fausto; I., De Munari; A., Scorzoni
abstract

The resistance noise associated with electromigration in Al-Cu lines has been simulated.


2002 - Appunti di Microelettronica [Monografia/Trattato scientifico]
Fantini, Fausto; Borgarino, Mattia
abstract

Il testo fornisce un quadro sintetico delle tecnologie impiegate in microelettronica.


2002 - Degradation based long-term reliability assessment for electronic components in submarine applications [Articolo su rivista]
V., Lista; P., Garbossa; T., Tomasi; Borgarino, Mattia; Fantini, Fausto; L., Gherardi; A., Righetti; M., Villa
abstract

Submarine Communication Systems require usage of high-rel components to guarantee long term reliability. A standard reliability assessment, based on observed failures during test, may be achieved only employing a very large number of component-hour, which is often unaffordable. An alternative reliability technique is proposed in this paper, based on the degradation monitoring of the components most relevant electrical parameters, subjected to different test flows. This analysis leads to a quantitative estimate of the components failure rate. (C) 2002 Elsevier Science Ltd. All rights reserved.


2002 - Design and screening of highly reliable 980nm pump lasers [Articolo su rivista]
G., Ghislotti; Fantini, Fausto
abstract

Presents a design and screening approach that can be adopted to improve reliability of high-power 980-nm semiconductor lasers. Flared-ridge waveguide chips were realized on GRIN-SCH single-quantum-well structures. Without any screening, flared devices, thanks to the reduced peak power and current density, showed a 20% reduction in failure rate with respect to devices with straight waveguide. By adopting extended screening criteria, a more reliable population was selected, showing a reduction by a factor of two in the failure rate extrapolated at standard operating conditions.


2002 - Low-Frequency Noise Characterisation of AlGaAs/GaAs HBT’s [Relazione in Atti di Convegno]
Borgarino, Mattia; M., Peroni; A., Cetronio; Fantini, Fausto
abstract

In the present paper we evaluated the fabrication process of AlGaAs/GaAs heterojunction Bipolar Transistors (HBT's) by means of low frequency noise characterizations carried out in the 100Hz-100kHz frequency range. We investigated the spectra of the base current fluctuations. The obtained results are compared with the data reported in the literature. The fabrication technology and the experimental set-up are briefly described.


2002 - The Correlation Resistance for Low-Frequency Noise Compact Modeling of Si/SiGe HBT's [Articolo su rivista]
Borgarino, Mattia; L., Bary; D., Vescovi; R., Menozzi; A., Monroy; M., Laurens; R., Plana; Fantini, Fausto; J., Graffeuil
abstract

The measurement of the correlation between the noise generators is a mandatory issue for the low-frequency noise modeling of bipolar transistors, and it is recognized as a very hard experimental task. In the present work, we introduce the concept of correlation resistance and we demonstrate that it can be usefully employed as a guideline for the low-frequency noise modeling in terms of intrinsic noise sources. As a proof of concept, the investigation technique is applied to submicron, BiCMOS-compatible Si/SiGe heterojunction bipolar transistors. It is pointed out that a satisfactory description of the transistor low-frequency noise behavior can be obtained by taking into account noise sources associated with surface recombination/fluctuation in the extrinsic base region.


2001 - A percolative approach to electromigration in metallic lines [Articolo su rivista]
C., Pennetta; L., Reggiani; G., Trefan; Fantini, Fausto; A., Scorzoni; I., De Munari
abstract

We present a stochastic model which simulates electromigration damage in metallic interconnects by biased percolation of a random resistor network in the presence of degradation and recovery processes. The main features of experiments including Black's law, times to failure distribution, current threshold for the onset of electromigration, etc are properly reproduced. Compositional effects showing up in early resistance changes measured on Al-0.5%Cu and Al-1%Si lines are also studied.


2001 - A percolative simulation of electromigration phenomena [Articolo su rivista]
Pennetta, C; Reggiani, L; Trefan, G; Fantini, Fausto; Demunari, I; Scorzoni, A.
abstract

Resistance degradation of metallic strips due to electromigation is studied within a percolative approach based on a random resistor network. Both defect generation and recovery driven by a current stress are considered. The main features of experiments performed on Al-0.5%Cu lines are well reproduced, thus providing a unified description of degradation processes in terms of physical parameters. (C) 2001 Elsevier Science B.V. All rights reserved.


2001 - Failure mechanisms in compound semiconductor electron devices [Capitolo/Saggio]
Fantini, Fausto; R., Menozzi; Borgarino, Mattia; L., Cattani; D., Dieci
abstract

In this chapter, we review the main failure mechanisms that affect advanced compound semiconductor electron devices such as high electron mobility transistors (HEMTs) and heterostructure bipolar transistors (HBTs).


2001 - Hot Carrier Effects in Si/SiGe HBT's [Articolo su rivista]
Borgarino, Mattia; J., Kuchenbecker; Jg, Tartarin; L., Bary; T., Kovacic; R., Plana; Fantini, Fausto; J., Graffeuil
abstract

Life tests were performed at room temperature on Si-SiGe HBTs by reverse biasing the base-emitter junction under open collector conditions. The effects on the DC, the low-frequency noise, and the microwave characteristics were investigated both by the analysis of experimental data and by simulations and analytical models. The stress-induced surface damage close to the emitter perimeter was identified to be the degradation mechanism mainly responsible for the variations observed, in all the investigated parameters


2001 - Investigation of the Hot-Carrier Degradation in Si/SiGe HBT’s by Intrinsic Low Frequency Noise Source Modeling [Relazione in Atti di Convegno]
Borgarino, Mattia; Kuchenbecker, J.; Tartarin, J. C.; Bary, L.; Kovacic, S.; Plana, R.; Menozzi, R.; Fantini, Fausto; Graffeuil, J.
abstract

The characterization of the excess low-frequency noise (LFN) properties of electronic devices is a useful tool in the field of reliability physics, because LFN is related to the interactions between charge carriers and material imperfections and defects. The LFN behavior of a bipolar transistor can be described in terms of extrinsic or intrinsic noise sources. The noise representation based on intrinsic noise sources allows more insight, because each source is associated with a particular transistor region. The availability of an intrinsic noise source model therefore allows to locate the degradation occurring during a life test.


2001 - Investigation of the role of compositional effects on electromigration damage of metallic interconnects [Articolo su rivista]
C., Pennetta; L., Reggiani; G., Treffan; Fantini, Fausto; A., Scorzoni; I., De Munari
abstract

Compositional effects are usually observed in the early stages of electromigration of interconnects made of Al alloys like Al-Cu and Al-Si. These effects are due to a variation of the fraction of the solute species (Cu or Si) dissolved into the Al matrix mainly due to heating effects. Here we investigate the role of compositional effects on electromigration phenomena by using a dynamical percolation model that we have recently developed. Our results well reproduce several phenomenological aspects typical of electromigration experiments. This agreement, together with the flexibility of our approach, suggests wide possibilities of further extending the model to study also the geometrical and structural effects. (C) 2001 Elsevier Science B.V. All rights reserved.


2001 - L'affidabilità e il DOE: progettazione degli esperimenti [Capitolo/Saggio]
Fantini, Fausto; Cattani, L.
abstract

Concetti base di affidabilità. Valutazoione e previsione dell'affidabilità. L'affidabilità in progettazione. La progettazione degli esperimenti.


2001 - Reliability physics of compound semiconductor transistors for microwave applications [Articolo su rivista]
Borgarino, Mattia; R., Menozzi; D., Dieci; L., Cattani; Fantini, Fausto
abstract

This paper reviews the reliability problems of compound semiconductor transistors for microwave applications. These devices suffer from specific failure mechanisms, which are related to their limited maturity, with the exception of the GaAs MESFETs, which exhibit a stable technology and an assessed reliability. The metallizations employed in high electron mobility transistors (HEMTs) already benefit from this assessment. However, HEMT are affected by concerns related to hot carriers and impact ionization. The trapping of carriers and the generation of defects in the different layers are responsible for the observed instabilities. The stability of the base dopant is the main reliability concern for heterojunction bipolar transistors (HBTs). Beryllium outdiffuses from the base into the emitter and causes device degradation. Carbon has a lower diffusivity, but is affected by the presence of hydrogen, which prompts gain variations. Finally the hot carriers reliability concern in SiGe HBTs is briefly reviewed. (C) 2001 Elsevier Science Ltd. All rights reserved.


2001 - The low frequency noise in electron devices: an engineering sight [Relazione in Atti di Convegno]
Borgarino, Mattia; Fantini, Fausto
abstract

Not available


2000 - Dynamic thermal characterization and modeling of packaged AlGaAs/GaAs HBT's [Articolo su rivista]
M., Busani; R., Menozzi; Borgarino, Mattia; Fantini, Fausto
abstract

In this work we show a method for the thermal dynamic modeling of packaged HBT's, The method employs a calibration step featuring pulsed measurements at different temperatures, and is based upon a 3-stage thermal resistance-capacitance model that describes the chip-solder-case system. A current pulse generator was designed and assembled in-house for pulsed characterization down to the microsecond range. The model was used to simulate the thermal transients of the collector current from the microsecond range to hundreds of seconds, for several different bias points in the forward active region, consistently showing a good match with the measured characteristics.


2000 - Evaluation of the hot carrier/ionizing radiation induced effects on the RF characteristics of low-complexity SiGe heterojunction bipolar transistors by numerical simulation [Articolo su rivista]
J., Kuchenbecker; Borgarino, Mattia; A., Coustou; R., Plana; J., Graffeuil; Fantini, Fausto
abstract

The hot carriers (HC)/ionizing radiation (IR) effects on the DC and RF characteristics of Si/SiGe HBTs have been investigated by numerical simulations. Once reproduced the typical DC degradation modes, the changes in the scattering (S) parameters were investigated up to 30 GHz. The degradation is caused by the increase of the Shockley-Hall-Read (SHR) surface recombination located around the emitter perimeter. Simulations were carried out by keeping the base or the collector current as they were before introducing the degradation mechanism. When the base current is kept constant, the most relevant effect is a reduction of \ S-21\ while the other S-parameters exhibit only minor changes. On the other hand, no remarkable hot carrier/ionizing radiation effects on the RF characteristics were observed when the collector current was kept constant. (C) 2000 Elsevier Science Ltd. All rights reserved.


2000 - Hot carriers Effects on the correlation resistance in Si/SiGe Heterojucntion Bipolar Transistors [Relazione in Atti di Convegno]
Borgarino, Mattia; L., Bary; J., Kuchenbecker; J. G., Tartarin; H., Lafontaine; S., Kovacic; R., Plana; J., Graffeuil; Fantini, Fausto
abstract

In this paper the effects of hot carrier on the correlation resistance in SiGe HBT's are investigated. Before the stress the correlation resistance was found to be comparable with the access series resistance while, after the stress, the correlation resistance decreases and the access series resistance increases. This increase suggests that the stress degrades the access regions of the transistor. On the other hand, the observed behaviour of the correlation resistance is explained in terms of an intrinsic noise source, Π-topology based low frequency noise model. It is shown that the correlation resistance is a useful indicator of surface recombination mechanisms. In particular, one intrinsic noise source in the model is associated with the degradation of the extrinsic base surface around the emitter perimeter.


2000 - La didattica in elettronica nella prospettiva del 3+2. [Articolo su rivista]
D., DAL CORSO; Fantini, Fausto; B., Riccò
abstract

Sono esaminati i problemi della didattica dell'elettronica alla luce della nuova legge di riforma.


2000 - Low-temperature spectrally resolved cathodoluminescence study of degradation in opto-electronic and microelectronic devices [Articolo su rivista]
C., Zanotti Fregonara; G., Salviati; BORGARINO, Mattia; L., Lazzarini; FANTINI, Fausto
abstract

This study reports on the microcharacterization of devices for optoelectronic and for microelectronic applications using low temperature (T 5 and 77 K) spectrally resolved cathodoluminescence (SCL). The mechanisms leading to compositional inhomogeneities in the regrowth regions of InP-based butt-coupled laser-waveguide devices for semiconducting optical amplifiers (SOAs) and for defect generation in the active and cladding layers of GaAs based pump lasers for erbium-doped optical fibre amplifiers (EDFAs) were studied. Beryllium outdiffusion in the base regions of GaAs-based heterojunction bipolar transistors (HBTs) after bias ageing was also studied. By comparing the CL results with TEM, SIMS and HRXRD studies and with the existing literature, the observed growth and operation induced defects were attributed, respectively, to the following mechanisms: recombination-enhanced defect glide (REDG) in the pump lasers, recombinationenhanced impurity diffusion (REID) in the HBTs and electrostatically induced growth flux instabilities in the butt-coupled laser-waveguide devices.


1999 - A proposal for a standard procedure for moderately accelerated electromigration tests on metal lines [Articolo su rivista]
A., Scorzoni; M., Impronta; I., De Munari; Fantini, Fausto
abstract

This work is aimed at proposing a standard procedure for moderately accelerated Electromigration (EM) tests applied to interconnection lines of the present and the next future generation of integrated circuits. The procedure has been tested on one metal level test structures using an AI-alloy metallization scheme, but can be easily applied to other materials as well as to metal lines with vias. Different existing standards have been taken into consideration to define this proposal: ASTM F1260-89, JEDEC JESD33-A, JESSI AC41. In the PROPHECY project, the focus was on wafer level reliability evaluation with fast methods, but fast EM methods using extremely accelerated stress conditions usually induce side-effects which can invalidate the results. As a consequence, this procedure suggests the use of moderately accelerated tests, together with a method for reducing the number of tests needed for a complete EM characterization. This procedure gives advice on the test structures to be used and on the preliminary steps to be performed before the EM tests. A measurement system, complying with the requirements of this procedure, is also briefly described. The methods described in this document apply to both package- and wafer-level measurements. In order to validate this procedure, EM tests have been performed on JESSI AC41 specimens. (C) 1999 Elsevier Science Ltd. All rights reserved.


1999 - A stochastic approach to failure analysis in electromigration phenomena [Articolo su rivista]
C., Pennetta; L., Reggiani; G., Trefan; Fantini, Fausto; I., Demunari; A., Scorzoni
abstract

Resistance degradation of thin film conductors is studied within a stochastic approach based on a random resistor network. Both defect generation and recovery are considered and assumed to depend on the stressing current. The main features of available experiments are well reproduced thus providing a unified interpretation of degradation processes and failure in terms of physical parameters. (C) 1999 Elsevier Science Ltd. All rights reserved.


1999 - Influence of surface recombination on the burn-in effect in microwave GaInP/GaAs HBT's [Articolo su rivista]
Borgarino, Mattia; R., Plana; S. L., Delage; Fantini, Fausto; J., Graffeuil
abstract

In this paper, we report on the early increase of the de current gain (burn-in effect) due to the electrical stress of carbon doped GaInP/GaAs heterojunction bipolar transistors (HBT's). Devices featuring different passivation layers, base doping, and emitter widths were investigated. The obtained data demonstrate that the burn-in effect is due to a reduction of the surface recombination located at the extrinsic base surface, around the emitter perimeter. It is concluded that the recombination centers are related to defects at the passivation/semiconductor interface and that, during the stress, they are passivated by hydrogen atoms released from C-H complexes.


1999 - Lifetime extrapolation for IGBT modules under realistic conditions [Articolo su rivista]
Ciappa, M.; Malberti, P.; Fichtner, W.; Cova, P.; Cattani, L.; Fantini, Fausto
abstract

In this work we propose a procedure for extrapolating the lifetime of IGBT modules due to bond wire lift-off based on accelerated test and on field data.


1999 - On the short and long term degradation of GaInP/GaAs heterojunction bipolar transistors [Articolo su rivista]
Borgarino, Mattia; R., Plana; S., Delage; Fantini, Fausto; J., Graffeuil
abstract

This work deals with the short and long term effects of a current stress performed at room temperature on Carbon doped GaInP/GaAs heterojunction bipolar transistors, The investigation has been carried out by means of DC characterizations and low frequency noise (LFN) measurements in the 250 Hz-100 kHz frequency range. During the stress the devices were biased in the forward active region, a collector-emitter voltage of 7.7 V and a collector current density of 2.2 x 10(4) A/cm(2) were imposed. The effect of the stress on the DC and LFN characteristics were compared and discussed in terms of two recombination mechanisms, The discussion points out that both extrinsic and intrinsic recombination processes have to be taken into account in order to justify the short and long term effects of the electrical stress. (C) 1999 Elsevier Science Ltd. All rights reserved.


1999 - Reliability investigation of InGaP/GaAs HBTs under current and temperature stress [Articolo su rivista]
Aa, Rezazadeh; Sa, Bashar; H., Sheng; Fa, Amin; Ah, Khalid; M., Sotoodeh; Ma, Crouch; L., Cattani; Fantini, Fausto; Jj, Liou
abstract

The reliability of InGaP/GaAs N-p-n heterojunction bipolar transistors (HBTs) with different base metal contact systems (Au/Zn/Au, Ti/Au, Ti/Pt/Au and the novel Ti/ZrB2/Au) under current and temperature stress is studied in this paper. We further report results of current stress on three p-GaAs doping Impurities namely Zn, Be and C. The effect of O+/H+ and O+/He+ ions, used in the fabrication of planar self-aligned HBTs, is also investigated in the stability of device de current gain, The instability phenomena typical of each factors and their effects on the HBT characteristics are reported. (C) 1999 Elsevier Science Ltd, All rights reserved.


1999 - Reliability issues in compound semiconductor heterojunction devices [Relazione in Atti di Convegno]
Fantini, Fausto; Borgarino, Mattia; L., Cattani; P., Cova; R., Menozzi; G., Salviati; C., Canali; G., Meneghesso; E., Zanoni
abstract

The failure mechanisms affecting electron devices based on compound semiconductors are reviewed.


1998 - A comparison between normally and highly accelerated electromigration tests [Articolo su rivista]
Foley, S.; Scorzoni, A.; Balboni, R.; Impronta, M.; DE MUNARI, I.; Mathewson, A.; Fantini, Fausto
abstract

Normally and highly accelerated electromigration tests on Al-Cu lines of different widths are compared.


1998 - Cathodoluminescence evidence of stress-induced outdiffusion of beryllium in AlGaAs/GaAs heterojunction bipolar transistors [Articolo su rivista]
Borgarino, Mattia; G., Salviati; L., Cattani; L., Lazzarini; C., Zanotti Fregonara; Fantini, Fausto; A., Carnera
abstract

Cathodoluminescence spectroscopy has been used for the first time in order to detect the base-dopant outdiffusion induced by current stress in AlGAs/GaAs Be-doped heterojunction bipolar transistors. The results show that diffusion of base dopant along the growth direction of the HBT structure occurs during the stress and this conclusion is confirmed by SIMS analysis. Integrated CL intensity variations induced by the stress suggest that the mechanism of recombination-enhanced impurity diffusion is responsible for diffusion of Be.


1998 - Correlation between light emission and currents in pseudomorphic HEMTs [Articolo su rivista]
Cova, P.; Fantini, Fausto; Manfredi, M.
abstract

In this paper we demonstrate the straight correlation between the integrated light emitted and the DC currents in GaAs-based pseudomorphic HEMTs biased at huigh drain voltage, when, due to hot electrons. impact ionization takes place.


1998 - Early Variations of the Base Current in In/C-doped GaInP/GaAs HBT's [Relazione in Atti di Convegno]
Borgarino, Mattia; R., Plana; S., Delage; H., Blank; Fantini, Fausto; J., Graffeuil
abstract

This paper reports on the early variations of the base current (burn-in effect) in SiN passivated, double-mesa processed, In/C-doped GaInP/GaAs HBT's induced by stressing the devices at room temperature and under different bias conditions


1998 - Electromigration testing of integrated circuit interconnections [Articolo su rivista]
Fantini, Fausto; J. R., Lloyd; I., De Munari; A., Scorzoni
abstract

The electromigration phenomenon has been one of the most intriguing physical problems in the semiconductor device reliability. The models to explain the phenomenon are here revised, together with the influence of materials and their microstructure. The various measuring techniques are described, including the design of special test patterns, and statistical data analysis is briefly reviewed.


1998 - Experimental evaluation of the minimum detectable outdiffusion length for AlGaAs/GaAs HBTs [Articolo su rivista]
Borgarino, Mattia; C., Voltolini; Fantini, Fausto; J., Tasselli; A., Marty
abstract

Triple mesa, Be-doped AlGaAs/GaAs HBTs were stressed at low temperature by forcing an emitter current density while the devices were biased in the forward active region. The effect on the d.c. characteristics was investigated and the results demonstrated that a base dopant outdiffusion is the degradation mechanism.By merging the experimental data with numerical simulations we obtained for the first time an experimental evaluation of the minimum detectable outdiffusion length. The measured value is in fair agreement with the theoretical value reported in the literature.


1998 - Hot electron degradation of the DC and RF characteristics of AlGaAs/InGaAs/GaAs PHEMT’s. [Articolo su rivista]
Borgarino, Mattia; R., Menozzi; Y., Baeyens; P., Cova; Fantini, Fausto
abstract

This paper reports on hot electron (HE) degradation of 0.25-μm Al0.25Ga0.75As/In0.2Ga0.8 As/GaAs PHEMT's by showing the effects of the hot electron stress on both the dc and rf characteristics. The changes of dc and rf behavior after stress turn out to be strongly correlated. Both can be attributed to a decrease of the threshold voltage yielding different effects on the device gain depending on the bias point chosen for device operation and on the bias circuit adopted: a fixed current bias scheme will minimize the changes induced by the stress. The work also presents a study of the dependence of device degradation on the stress bias condition.


1998 - On the correlation between drain and gate currents and light emission in GaAs PHEMTs biased in the impact ionisation regime [Articolo su rivista]
Cova, P.; Menozzi, R.; Pavesi, M.; Pavesi, S.; Manfredi, M.; Fantini, Fausto
abstract

In this work we investigate, by means of electrical and both spectral and integral electroluminescence measurements, the light emission mechanisms in AlGaAs/InGaAs/GaAs peudomorphic HEMTs biased at high drain voltage.


1998 - On the effect of power cycling stress on IGBT modules [Articolo su rivista]
P., Cova; Fantini, Fausto
abstract

IGBT reliability is becoming of great relevance, due to the range of application of these devices. Nevertheless, no standard test methods have been established, in order to evaluate their power cycling reliability. On this paper we report on the effect of Delta T and T-jmax on the power cycling capability of IGBT dice, by means of a matrix of stress cycles with different values of Delta T and T-jmax. Failure analysis has been performed, in order to understand the failure mechanisms induced by the stress. (C) 1998 Elsevier Science Ltd. All rights reserved.


1998 - Pulsed current stress of Berillium doped AlGaAs/GaAs HBTs [Articolo su rivista]
L., Cattani; Borgarino, Mattia; Fantini, Fausto
abstract

The major concern for reliability of Berillium doped HBTs is the diffusion of the base dopant towards the emitter. This degradation can be enhanced by the device self-heating and/or by REID mechanism. In order to separate the thermal and REID components to the Berillium outdiffusion we performed a pulsed current stress on AlGaAs/GaAs HBTs. In this paper we report on results obtained with different values of the duty cycles for this current.


1998 - Reliability of Gaas-based HBTs [Relazione in Atti di Convegno]
Fantini, Fausto; Borgarino, Mattia; L., Cattani; R., Menozzi
abstract

Most of the applications of the Heterojunction Bipolar Transistors (HBTs) are in the field of telecommunications, where device reliability is a key issue. This work reports on a major HBT reliability issue: base dopant stability. In particualr, the most two widely employed base dopnats are addressed: Beryllium and Carbon. The instability phenomena typical of each doping impurity, and their effects on the HBT cahracteristics are briefly overviewed in this paper.


1998 - The influence of the emitter orientation on the DC and low frequency noise characteristics of GaInP/GaAs HBTs [Relazione in Atti di Convegno]
Borgarino, Mattia; J. G., Tartarin; R., Plana; S., Delage; J., Graffeuil; Fantini, Fausto
abstract

The present paper focuses on the influence of the emitter orientation on the electrical characteristics of GaInP/GaAs HBTs. The investigations was carried out by means of DC and Low Frequency Noise (LFN) measurements in the 250Hz-100kHz frequency range. Samples featuring a conventional Carbon-doped base and Indium-codoped/Carbon-doped base were available. We demonstrated that the emitter orientation has an impact on the DC and LFN characteristics of HBTs. This behaviour has been attributed to piezoelectric effects and surface recombinations in the extrinsic base region around the emitter perimeter.


1997 - A study of hot electron degradation effects in pseudomorphic HEMTs [Articolo su rivista]
P., Cova; R., Menozzi; Fantini, Fausto; M., Pavesi; G., Meneghesso
abstract

In this work we report on hot-electron stress experiments performed on commercial AlGaAs/InGaAs/GaAs pseudomorphic HEMTs.


1997 - Analysis of hot electron degradation in pseudomorphic HEMTs by DCTS and LF noise characterisation [Articolo su rivista]
N., Labat; N., Saysset; A., Touboul; Y., Danto; P., Cova; Fantini, Fausto
abstract

Commercial pseudomorphic AlGaAs/InGaAs HEMTs designed for low noise operation have demonstrated weak sensitivity to hot electron stress. We have investigated underlying physical mechanisms by LF channel noise analysis and Drain Current Transient Spectroscopy (DCTS).


1997 - Are high resolution resistometric methods really useful for early detection of electromigration damage? [Articolo su rivista]
A., Scorzoni; S., Franceschini; R., Balboni; M., Impronta; I., DE MUNARI; Fantini, Fausto
abstract

In this paper the use of High Resolution Resistometric Techniques for early detection of electromigration strength of Al-Cu/TiN/Ti stripes is analyzed.


1997 - Electrical and thermal simulation of local effects for electromigration [Articolo su rivista]
Borgarino, Mattia; V., Petrescu; L., Brizzolara; I., De Munari; Fantini, Fausto
abstract

The aim of this work is to investigate the distribution of the local current density and temperature gradients along the tests patterns employed for the evaluation of the electromigration phenomena in metal tracks.


1997 - On the effects of hot electrons on the DC and RF characteristics of lattice-matched InAlAs/InGaAs/InP HEMT's [Articolo su rivista]
R., Menozzi; Borgarino, Mattia; Y., Baeyens; M., Van Hove; Fantini, Fausto
abstract

The authors for the first time present results of hot electron stressing of InAlAs/InGaAs/InP high electron mobility transistors (HEMTs). High drain bias, room temperature stress cycles have been applied to 0.3 μm, SiN-passivated, lattice-matched devices, and the changes of the DC and RF (up to 50 GHz) characteristics have been studied. Both the DC and RF device gain degrade after stressing; the effect of the stress on the unity current gain cutoff frequency fT is studied under different bias conditions. Results indicate that surface degradation may be responsible for the observed changes


1997 - The effect of Hot Electron Stress on the DC and Microwave Characteristics of GaAs-PHEMTs and InP-HEMTs [Relazione in Atti di Convegno]
R., Menozzi; Borgarino, Mattia; P., Cova; Y., Baeyens; M., Van Hove; Fantini, Fausto
abstract

This work reports on hot electron stress experiments performed on SiN passivated AlGaAs/InGaAs/ GaAs pseudomorphic HEMTs and InAlAs/InGaAs/InP lattice-matched HEMTs.


1997 - The effect of the base dopant concentration on the stability of Be-doped AlGaAs/GaAs HBTs devices [Articolo su rivista]
Borgarino, Mattia; R., Losi; Fantini, Fausto; M., Schussler; H. L., Hartnagel; S., Franchi; A., Bosacchi
abstract

The impact of the base dopant lavel on the stability of Be-doped AlGaAs/GaAs HBTs is investigated by means of forward current stress carried out at room temperature. The results show that the degradation mechanism is due to the Beryllium outdiffusion: the higher is the base dopant concentration, the larger the degradation.


1997 - The thermally balanced bridge technique (TBBT): a new high resolution resistometric measurement technique for the study of electromigration-induced early resistance changes in metal stripes [Articolo su rivista]
J., VAN OLMEN; W., DE CEUNINCK; L., DE SCHEPPER; A., Goldoni; A., Cervini; Fantini, Fausto
abstract

A new high resolution resistometric measurement technique has been developed in order to perform accurate early resistance change measurements on metal lines submitted to high current densities.


1997 - Thermal characterisation of IGBT power modules [Articolo su rivista]
Cova, P.; Ciappa, M.; Franceschini, G.; Malberti, P.; Fantini, Fausto
abstract

In this paper we report on experimental techniques for the thermal characterization of IGBT power modules.


1996 - Breakdown walkout in pseudomorphic HEMT's [Articolo su rivista]
R., Menozzi; P., Cova; C., Canali; Fantini, Fausto
abstract

In this work we show for the first time evidence of gate-drain breakdown walkout due to hot electrons in pseudomorphic AlGaAs-InGaAs-GaAs HEMTs (PHEMTs). Experiments performed on passivated commercial PHEMTs show that hot electron stress cycles induce a large and permanent increase of the gate-drain breakdown voltage. Three-terminal and two-terminal stress conditions are compared, the former producing a much larger walkout due to hot electrons flowing in the channel. Experimental results indicate that a build-up of negative charge in the region between gate and drain is responsible for the breakdown walkout, due to a local widening of the depletion region and a reduction of the peak electric field


1996 - Design of a test structure to evaluate electro-thermomigration in power ICs [Articolo su rivista]
I., DE MUNARI; F., Speroni; M., Reverberi; C., Neva; L., Lonzi; Fantini, Fausto
abstract

The design of a novel test structure to study the influence of electromigration and thermomigration in the large dimension metal lines used in power integrated circuits is reported.


1996 - Negative Vbe shift due to base dopant outdiffusion in DHBT [Articolo su rivista]
Borgarino, Mattia; F., Paorici; Fantini, Fausto
abstract

By applying a light electrical stress at room temperature to an ALE grwon double mesa processed DHBT and comparing the experimental data with numerical simulations new interesteing results are obtained.


1996 - Resistance change due to Cu transport and precipitation during electromigration in submicrometric Al-0.5%Cu lines [Articolo su rivista]
A., Scorzoni; I., DE MUNARI; R., Balboni; F., Tamarri; A., Garulli; Fantini, Fausto
abstract

In this work we describe the resistance changes due to Cu transport and precipitation during electromigration in 0.5 micron wide Al-0.5%Cu lines.


1996 - The effect of hot electron stress on the DC and microwave characteristics of AlGaAs/InGaAs/GaAs PHEMTS [Articolo su rivista]
R., Menozzi; Borgarino, Mattia; P., Cova; Y., Baeyens; Fantini, Fausto
abstract

The work reports on hot electron reliability of 0.25 micron Al(0.25)Ga(0.75)As/In(0.2)Ga(0.8)As/GaAs PHEMTs from the viewpoint of both DC and RF characteristics.


1995 - Activation energy in the early stage of electromigration in Al-1%Si/TiN/Ti bamboo lines [Articolo su rivista]
I., DE MUNARI; A., Scorzoni; F., Tamarri; Fantini, Fausto
abstract

The presence of a different activation energy for the electromigration during the early phase of accelerated tests is demonstrated and discussed.


1995 - Band-to-band recombination peak in the light emission of commercial pseudomorphic HEMTs [Articolo su rivista]
R., Menozzi; P., Cova; A., Pisano; Fantini, Fausto; M., Pavesi; P., Conti
abstract

non disponibile


1995 - Enhancement and Degradation of Drain Current in Pseudomorphic AlGaAs/InGaAs HEMT's Induced by Hot-Electrons. [Relazione in Atti di Convegno]
C., Canali; P., Cova; E., De Bortoli; Fantini, Fausto; G., Meneghesso; R., Menozzi; E., Zanoni
abstract

New failure mechanisms induced by hot-electrons in AlGaAs/InGaAs pseudomorphic HEMT's have been identified by means of accelerated testing of commercial devices from four different supplier.


1995 - High base current ideality factors due to trap-assisted band-to-band tunneling in AlGaAs/GaAs HBTs [Articolo su rivista]
Borgarino, Mattia; R., Menozzi; Fantini, Fausto; M., Schussler; H. L., Hartnagel
abstract

Anomalous (>3) ideality factors in the base current of AlGaAs/GaAs HBTs, resulting in poor current gain performance, are modeled assuming a tunneling mechanism in the base-emitter space charge region assisted by centers in the forbidden gap. The model is validated by means of measurement of forward I-V characteristics as a function of temperature.


1995 - On the ASTM electromigration test structure applied to Al-1%Si/TiN/Ti bamboo metal lines [Articolo su rivista]
I., DE MUNARI; M., Vanzi; A., Scorzoni; Fantini, Fausto
abstract

The applicability of NIST-ASTM electromigration test patterns when used to test "bamboo" metal lines is discussed.


1995 - Thermal stability of Al/Ni gate AlGaAs/GaAs HEMT's [Articolo su rivista]
I., DE MUNARI; Fantini, Fausto; P., Conti
abstract

The study of the instability of gate contacts of Al/Ni gate AlGaAs/GaAs HEMT's was performed by means of storage tests carried out at three different temperatures: 200, 240 and 300°C.


1994 - Drawbacks to using NIST electromigration test structures to test bamboo metal lines [Articolo su rivista]
I., DE MUNARI; A., Scorzoni; F., Tamarri; D., Govoni; F., Corticelli; Fantini, Fausto
abstract

In this work the applicability of NIST electromigration test patterns when used to test “bamboo” metal lines is discussed. Wafer level tests on passivated and nonpassivated samples employing the Al-1%Si/TiN/Ti metallization scheme were performed. Straight metal lines 1000 μm long and 0.9 μm or 1.4 μm wide were tested at two different current densities, j=3 MA/cm2 and J=4.5 MA/cm2, keeping the stress temperature at T=230°C. The failures occurred mainly in the end segment areas and hindered the evaluation of the electromigration resistance of the test lines. In order to avoid this problem, completely different test patterns containing a number of geometrical variations should be defined


1994 - Electrical properties and thermal stability of MBE-grown Al/AlxGa1-xAs/Al(0.25)Ga(0.75)As Schottky barriers [Articolo su rivista]
A., Bosacchi; S., Franchi; E., Gombia; R., Mosca; Fantini, Fausto; R., Menozzi; S., Naccarella
abstract

The effects of the Al mole fraction of a thin (4 nm) AlxGa1-xAs cap on the barrier height and the thermal stability of Al/AlxGa1-xAs/Al0.25 Ga0.75As Schottky barriers prepared in situ by MBE have been investigated. The behaviour of the barrier heights and the ideality factors of diodes after annealing up to 435°C are studied


1993 - Design and Simulation of a Test Pattern for Three-Dimensional Latch-up Analysis [Articolo su rivista]
I., DE MUNARI; R., Menozzi; Fantini, Fausto
abstract

The design of a test pattern for the identification of the firing of the latch-up in CMOS integrated circuits is described.


1993 - Electromigration in Thin-Films for Microelectronics [Articolo su rivista]
G. L., Baldini; I., DE MUNARI; A., Scorzoni; Fantini, Fausto
abstract

The effcts of the electromigration in the metallic stripes in ICs is reviewed.


1993 - Thermal Stability of Al/AlGaAs and Al/GaAs/AlGaAs (MBE) Schottky barriers [Articolo su rivista]
A., Bosacchi; Franchi, S. E.; E., Gombia; R., Mosca; Fantini, Fausto; Franchi, S. T.; R., Menozzi
abstract

Outstanding stability has been observed in Al/AlxGa1-xAs and Al/GaAs/AlxGa1-xAs (x=0.25) Schottky barriers prepared by depositing Al in situ by MBE on annealing up to 400 degrees C. Conventionally evaporated barriers have been fabricated and compared with epitaxial ones. The changes in barrier height and ideality factor induced by annealing are reported.


1993 - Very high temperature test of InP-based Laser Diodes [Articolo su rivista]
M., Tesauri; G., Chiorboli; P., Cova; Fantini, Fausto; F., Magistrali; D., Sala
abstract

The reliability of DHBC and DFB InGaAsP/InP lasers have been evaluated by means of high-temperature operating life tests between 80 and 110°C.


1992 - ESD induced degradation mechanisms of InGaAsP lasers [Articolo su rivista]
F., Magistrali; D., Sala; G., Salmini; M., Vanzi; Fantini, Fausto; M., Giansante; L., Zazzetti
abstract

The sensitivity of InGaAsP/InP buried crescent lasers to ESD phenomena was deeply analysed, starting from the need to explain and prevent sudden failures during equipment manufacturing and test.


1992 - Reliability of compound semiconductor devices [Articolo su rivista]
Fantini, Fausto; F., Magistrali
abstract

This paper reviews the reliability of III-V semiconductor devices with particular attention to the failure mechanisms typical of these structures.


1991 - Electromigration in thin-film interconnection lines: models, methods and results [Articolo su rivista]
A., Scorzoni; B., Neri; C., Caprile; Fantini, Fausto
abstract

Electromigration /EM) in thin film interconnection lines is one of the major concerns for the development of ULSI devices, employing advanced design rules. Different models have been proposed, but the complete comprehension of the basic physical mechanisms leading to EM is still unsatisfactory. In this work, well-established results and unsolved problems are reviewed.


1991 - ESD-Related Latent Failures of InGaAsP/InP Laser Diodes for Telecommunication Equipment [Relazione in Atti di Convegno]
F., Magistrali; D., Sala; G., Salmini; Fantini, Fausto; M., Giansante; M., Vanzi
abstract

The paper presents a case history of ESD-related latent failures of InGaAs/InP laser diodes.


1991 - TEM observation of GaAs/GaAlAs laser diodes degraded in field operation [Articolo su rivista]
F., Magistrali; D., Sala; M., Vanzi; Fantini, Fausto; F., Corticelli; A., Migliori
abstract

Cross-section TEM analysis was applied to the dice of degraded DH GaAs/GaAlAs oxide-stripe laser diodes to enable a deeper understanding of the origin of chip-related failures in the field operation. The technique enabled the growth of dislocation loops confined inside the active layer to be identified as the failure mechanism responsible for the degradation.


1991 - The Al-1% Si/TiN/Ti interconnection scheme: electromigration and reliability extrapolation [Articolo su rivista]
C., Caprile; G., Specchiulli; D., Sala; Fantini, Fausto
abstract

The electromigration performance of Al-1%Si/TiN/ti metal scheme is investigated both for contacts and for stripes and compared with the results for the standard Al-1%Si metallization.


1990 - A Retinal CCD Sensor for Fast 2D Shape Recognition and Tracking [Articolo su rivista]
I., Debusschere; E., Bronckaers; C., Claeys; G., Kreider; J., VAN DER SPIEGEL; P., Belluti; G., Soncini; P., Dario; Fantini, Fausto; G., Sandini
abstract

A human-retina -like image sensor has been developed for applications in robotics.


1990 - Life tests and field results of GaAs FETs. [Articolo su rivista]
P., Brambilla; Fantini, Fausto; F., Magistrali; M., Sangalli
abstract

The overall workplan for assuring the reliability of GaAs MESFETS is presented, as a result of 10 years of industrial experience. The importance of an accurate evaluation of failure mechanisms and acceleration factors is pointed out, describing problems and criticalities related to the reliability testing and the failure analysis of this kind of devices.


1990 - Metal-GaAs interaction and contact degradation in microwave MESFETs [Articolo su rivista]
E., Zanoni; A., Callegari; C., Canali; Fantini, Fausto; H. L., Hartnagel; F., Magistrali; A., Paccagnella; M., Vanzi
abstract

This work reports and critically reviews failure mechanisms induced by metal-GaAs interaction and contact degradation in low and medium power GaAs MESFETs in the framework of a comprehensive reliability evaluation test plan, performed mainly on commercially purchesed devices manufactured by different technologies.


1990 - Reliability of GaAs MESFETs [Relazione in Atti di Convegno]
B., Ricco'; Fantini, Fausto; F., Magistrali; P., Brambilla
abstract

The paper presents new data on the reliability of GaAs MESFETs for microwave telecommunications obtained from the analysis of field repairs and accelerated tests. This work represents a systematic investigation of devices in the context of real applications, thus providing a significative contribution to the state of the art in the field.


1990 - Sensori di immagine a CCD. [Articolo su rivista]
A., Simone; C., Claeys; Fantini, Fausto
abstract

La crescente applicazione di sensori ottici aklla visione automatica ha ridestato l'interesse per i dispositivi CCD. In questo lavoro vengono richiamati i principi base del funzionamento dei CCD e le strutture impiegate per la realizzazione dei sensori di immagine.


1990 - VLSI Reliability: Contributions from a Three Year National Research Program [Articolo su rivista]
G., Soncini; C., Canali; E., Zanoni; F., Corsi; A., Diligenti; Fantini, Fausto; V. A., Monaco; G., Masetti; C., Morandi
abstract

The contnuous trend to further I.C. miniaturization implies increased local electric field strength and power dissipation density, and a "perverse scaling" behaviour of metal interconnections and contacts. This will result in new failure mechanisms while old ones, non under control, may become a threat again.Thi work reports on the most relevant results, related to VLSI reliability, obtained by the seven Univeristy Research Yeams involved in a three years Research Program sponsored by the Italian Ministero Pubblica Istruzione.


1989 - A Foveated Retina-Like Sensor Using CCD Technology [Capitolo/Saggio]
J., VAN DER SPIEGEL; G., Kreider; C., Claeys; I., Debusschere; G., Sandini; P., Dario; Fantini, Fausto; P., Bellutti; G., Soncini
abstract

A CCD imager whose sampling structure is loosely modeled after the biological visual system is decribed.


1989 - Degradation mechanisms in insulating films on Silicon [Capitolo/Saggio]
G., Baccarani; Fantini, Fausto
abstract

Introduction. Conduction mechanisms in thin oxides. Instabilities due to contamination.


1989 - Latch-up in CMOS Integrated Circuits [Capitolo/Saggio]
Fantini, Fausto; M., Muschitiello; E., Zanoni
abstract

The physics of latch-up. Electrical characterization. Analytical techniques. Layout and technological improvements for avoiding latch-up.


1989 - On the validity of resistometric technique in electromigration studies of narrow stripes [Articolo su rivista]
Fantini, Fausto; G., Specchiulli; C., Caprile
abstract

In the framework of the development of a submicron CMOS technology, we investigate the reliability of Al stripes 1.5-8 micron wide and compared the results obtained with various techniques; in particular in this paper the resistometric method is compared with the standard MYF technique for the narrowest stripes.


1987 - Degradation mechanisms induced by high current density in Al-gate GaAs MESFETs [Articolo su rivista]
C., Canali; Fantini, Fausto; A., Scorzoni; L., Umena; E., Zanoni
abstract

Degradation mechanisms induced by high current density in Al-gate GaAs MESFETs


1987 - Electromigration effects in power MESFET rectifying and ohmic contacts [Articolo su rivista]
C., Canali; F., Chiussi; Fantini, Fausto; L., Umena; M., Vanzi
abstract

Both gate and source/drain electromigration are significant failure mechanisms in power MESFTs. The correlation between electromigration effects due to high current density and measured electrical degradation is investigated in devices of different technologies. A safety zone of operation for ohmic contact electromigration is defined.


1987 - Gold-based gate-sinking enhanced by inhomogeneities in power MESFETs [Articolo su rivista]
C., Canali; G., Donzelli; Fantini, Fausto; M., Vanzi; A., Paccagnella
abstract

Gate contact degradation of power MESFETs with gold-based gate metallisations is enhanced by local inhomogeneities, such as thermal gradients and border effects.


1987 - Text fixture for MESFET reliability life tests [Articolo su rivista]
C., Canali; F., Chiussi; Fantini, Fausto; G., Muzzin; L., Umena
abstract

DC tests may be the method on which to found an unitary methodology for setting and analysis of GaAs MESFET reliability studies. Each failure mechanism must be stressed without introducing erroneous one, due to the artificial conditions of accelerated tests. A text fixture for these tests must enable the hgghest contro of aging conditions.


1987 - Un'introduzione al problema delle scariche elettrostatiche nei circuiti integrati. [Articolo su rivista]
R., Benetti; Fantini, Fausto; B., Riccò
abstract

Questo lavoro affronta il problema dell'influenza delle scariche elettrostatiche (ESD-ElectroStatic Discharge) sui dispositivi a semiconduttori, fenomeno che rappresenta una delle cause più comuni di guasto, in particolare nei circuiti integrati MOS.


1986 - A SEM based system for a complete characterisation of latch-up in CMOS integrated circuits [Articolo su rivista]
C., Canali; Fantini, Fausto; M., Giannini; A., Senin; M., Vanzi; E., Zanoni
abstract

An electron beam testing system was established foe a complete and detailed analysis of latch-up in CMOS integrated circuits.


1986 - Affidabilità e fisica dei guasti nei circuiti integrati in silicio [Articolo su rivista]
Fantini, Fausto; M., Vanzi
abstract

L'affidabilità dei circuiti integrati riveste un'importanza crescente: ne vengono richiamati definizione e metodi di calcolo. Sono quindi esaminati i meccanismi di guasto principali, classificandoli secondo la localizzazione nella tessera di silicio.


1986 - Evaluation of current density distribution in MESFET gates [Articolo su rivista]
A., Scorzoni; C., Canali; Fantini, Fausto; E., Zanoni
abstract

An analytical evaluation of the distribution of the current density both along the gate finger and perpendicular to the metal/semiconductor interface in MESFET transistors is reported for the case of forward-biased gate junctions. Examples are given for two gate resistances per unit length to evidence the current crowding effect which appears near the gate pad on increasing the gate resistance.


1986 - GaAs MESFET technology and reliability aspects. [Articolo su rivista]
P., Brambilla; Fantini, Fausto; G., Guarini; G., Mattana; G. F., Piacentini
abstract

Tis paper revies recent efforts and developments in microwave GaAs MESFET's both from a technological point of view and reliability evaluation.


1986 - Gate metallization 'sinking' into the active channel in Ti/W/Au metallized power MESFET's [Articolo su rivista]
C., Canali; F., Castaldo; Fantini, Fausto; D., Ogliari; L., Umena; E., Zanoni
abstract

Commercial power MESFET's with Ti/W/Au gate metallization show a failure mode consisting of a decrease in Idssand Vpand an increase in R0. The failure mechanism was investigated by electrical and structural analyses with SEM, microprobe, and Auger spectrometry, and turns out to be a thermally activated Au-GaAs interdiffusion leading to encroachment of the gate metal on the channel. This may be common to all Au-metallized MESFET's and can lead to burn-out of devices.


1986 - Increase in barrier height of Al/n-GaAs contacts induced by high current [Articolo su rivista]
C., Canali; L., Umena; Fantini, Fausto; A., Scorzoni; E., Zanoni
abstract

High forward-gate current (HFGC) density induces an increase of the Al/n-GaAs barrier height from 0.8 to 0.96 eV, thus suggesting the formation of an GaxAl1-xAs layer at the interface. Results show that this interaction is more enhanced by the electron current from the semiconductor to the metal than by thermal treatments. The intense electron flow is believed to contribute to the breaking of the interfacial oxide layer present at the metal-semiconductor interface, thus promoting Al/GaAs interdiffusion. Data were obtained on power MESFET's with Al metallized gate.


1986 - Observation of latch-up phenomena in CMOS IC's by means of Digital Differential Voltage Contrast [Articolo su rivista]
Fantini, Fausto; M., Vanzi; C., Morandi; E., Zanoni
abstract

The latch-up phenomenon in CMOS ICs is studied by means of a SEM observation technique that is based on capacitively coupled voltage contrast and is characterized by digital beam control and image acquisition. Passivated devices are studied at low beam energies, without interfering with their electrical behavior. The comparison between images taken in the latched and nonlatched state allows reliable identification of the latch-up current paths and thus of the latched site. The performance of the technique is demonstrated by three examples which refer to one standard and two custom CMOS ICs.


1986 - Reliability evaluation of plastic packaged devices for long life applications by THB test [Articolo su rivista]
P., Brambilla; C., Canali; Fantini, Fausto; F., Magistrali; G., Mattana
abstract

The reliability of transistors, bipolar and CMOS integrated circuits encapsulated in different types of plastic packages was investigated by using the 85°C/85%R.H. test with applied bias and thr results compared with a long term operating life test.


1985 - Degradation mechanisms induced by temperature in power MESFETs [Articolo su rivista]
C., Canali; Fantini, Fausto; L., Umena; E., Zanoni
abstract

Two independent failure mechanisms, mainly induced by temperature, were observed in unpassivated, Au-metallised, commercially available power MESFETs. They result in a high gate/source (drain) leakage and in an increase in the open channel resistance, and may explain the burn-out of the devices in practical applications.


1985 - Failure modes and mechanisms for VLSI ICs [Articolo su rivista]
Fantini, Fausto; C., Morandi
abstract

Knowledge of the electrical failure modes and of the physical mechanisms that cause faults is fundamental to implementing realistic fault models. Therefore, failure physics is the basis of effectual test sequence generation, and can give guidelines also for the design of testable and reliable integrated circuits. In the paper the failure modes and mechanisms of complex integrated circuits are reviewed. Faults are classified with respect to their allocation in the devices. Bulk defects, and failures in the dielectric layers, metallisation and package interconnections are then examined. Special attention is devoted to failures spurred by the reduction of dimensions for VLSI (scaling).


1985 - Potential of Digital Differential Voltage Contrast for the observation of latch-up phenomena in CMOS ICs. [Articolo su rivista]
Fantini, Fausto; M., Vanzi; C., Morandi; G., Soncini
abstract

The Digital Differential Voltage Contrast in a SEM has been applied to the observation of the latch-up phenomenon in CMOS ICs.


1984 - Failures induced by electromigration in ECL 100k devices [Articolo su rivista]
C., Canali; Fantini, Fausto; E., Zanoni; A., Giovannetti; P., Brambilla
abstract

Reliability of ECL 100k devices using Al (4%wt Cu, 1%wt Si) double level metallization, isoplanar technology with shallow, 0.25 micron, base-emitter junctions was evaluated by means of high current and high temperature stresses.


1984 - Power GaAs MESFET: reliability aspects and failure mechanisms [Articolo su rivista]
C., Canali; F., Castaldo; Fantini, Fausto; D., Ogliari; M., Vanzi; M., Zicolillo; E., Zanoni
abstract

In this paper we analyse and discuss some failure analyses performed on power GaAs MESFET. The pieces came both from accelerated tests and from the field.


1984 - PROBLEMATICHE CONNESSE CON IL COLLAUDO DEI CIRCUITI INTEGRATI DIGITALI [Articolo su rivista]
Fantini, Fausto; C., Morandi; A., Senin
abstract

Si passano in rassegna le problematiche legate al collaudo dei circuiti integrati a grande densità di integrazione, con particolare attenzione all'inadeguatezza dei modelli di guasto più diffusi, ai problemi della generazione delle sequenze di collaudo e della diagnostica.


1984 - Reliability problems with VLSI [Articolo su rivista]
Fantini, Fausto
abstract

The extraordinary development of the integrated circuits has gone hand in hand with an increase in reliability; however the speed of evolution itself brings about greater reliability risks, due to strong competition in the market, and the reduction in the dimensions of the devices causes an increase in the electric fields and current densities.The failure mechanisms that are expected to be most dangerous are thin oxide breakdown, hot electron effects, metal-semiconductor interactions, electromigration and soft errors.


1983 - Anodic Gold corrosion in plastic encapsulated devices [Articolo su rivista]
Brambilla, E.; Brambilla, P.; Canali, C.; Fantini, Fausto; Vanzi, M.
abstract

Experimental results of Gold metallization failures in semiconductor devices due to the corrosion of Gold in the absence of a complexing medium or contaminants are reported. In particular, we show the corrosion of anodically biased lines which was observed on unpassivated plastic encapsulated high-frequency transistors and on passivated linear integrated circuits operating at 85°C, 85% R.H., for a few thousend hours.


1983 - Failure mechanisms and analysis of very large scale integrated circuits [Relazione in Atti di Convegno]
Fantini, Fausto; G., Mattana
abstract

The failure mechanisms affecting advanced Silicon integrated circuits are reviewed.


1983 - Investigation of information loss mechanisms in EPROMs [Articolo su rivista]
Bertotti, D.; Fantini, Fausto; Morandi, C.
abstract

The paper reports the results of accelerated life tests on p- and n-channel EPROMs, and compares the indication thus obtained with data from the field.


1983 - L'affidabilità dei dispositivi a semiconduttore - parte prima [Articolo su rivista]
Fantini, Fausto; G., Mattana; E., Zanoni
abstract

In questo articolo, dopo aver definito l'affidabilità come disciplina e come proprietà degli oggetti, vengono introdotte le funzioni statistiche più usate per l'analisi dei dati e la misura dell'affidabilità.


1983 - L'affidabilità dei dispositivi a semiconduttore - parte seconda [Articolo su rivista]
Fantini, Fausto; G., Mattana; E., Zanoni
abstract

In questa seconda parte vengono presentati i fenomeni chimico-fisici che causano i guasti dei componenti elettronici.


1983 - Updating of CMOS reliability [Articolo su rivista]
P., Brambilla; Fantini, Fausto; G., Mattana
abstract

Updated results of massive life tests on CMOS are reported. The failure rate derived from laboratory conditions is extrapolated for long life use and compared with field results. Failure mechanism distribution is also reported.


1982 - Bipolar Schottky logic device failure modes due to contact metallurgical degradation [Articolo su rivista]
Canali, C.; Fantini, Fausto; Vanzi, M.; Soncini, G.; Zanoni, E.
abstract

Failure modes of bipolar Schottky logic devices due to metallurgical degradation of PtSi/Ti-W/Al contacts were studied.


1982 - Electrical degradation of n-Si/PtSi/(Ti-W)/Al Schottky contacts induced by thermal treatments [Articolo su rivista]
Canali, C.; Fantini, Fausto; Zanoni, E.
abstract

Degradation of n-Si/PtSi/(ti-W)/Al Schottky contacts induced by thermal treatments.


1982 - EPROM testing - part I: theoretical considerations [Articolo su rivista]
Alliney, S.; Fantini, Fausto; Morandi, C.
abstract

Testing may be more expensive for EPROMs than for other memories, because program and erasure cycles are much longer than read cycles, and therefore the test procedure must not include more than one program and one erasure step. In this paper EPROM operation is modeled by a sequential machine those state and output equations are derived according to boolean matrix algebra.


1982 - EPROM testing - part II: application to 16K N-channel devices [Articolo su rivista]
Alliney, S.; Bertotti, D.; Fantini, Fausto; Morandi, C.
abstract

This paper shows how the fault models introduced in the parent paper [1] may be applied to a commercial device.


1982 - Failure modes induced in TTL-LS bipolar logics by negative inputs [Articolo su rivista]
C., Canali; Fantini, Fausto; G., Soncini; P., Venturi; E., Zanoni
abstract

Logic faults induced by negative inputs in TTL-LS bipolar devices have been analyzed. Failures are primarely induced by parasitic lateral npn transistors.


1982 - Interdiffusion and compound formation in the c-Si/PtSi/(Ti-W)/Al system [Articolo su rivista]
Canali, C.; Celotti, G.; Fantini, Fausto; Zanoni, E.
abstract

SEM, microprobe measurements, AES and X-ray diffraction were used to investigate interdiffusion phenomena occurring in the c-Si/PtSi/(Ti-W)/Al system widely used in silicon integrated circuits.


1981 - CMOS reliability: a useful case history to revise extrapolation effectiveness, lenght and slope of the learning curve [Articolo su rivista]
Brambilla, P.; Fantini, Fausto; Malberti, P.; Mattana, G.
abstract

In this paper are compared the reliability data obtained from accelerated life tests with those from massive life test by more than 16,000 devices.


1981 - On the use of matrix algebra for the description of EPROM failures [Articolo su rivista]
Morandi, C.; Fantini, Fausto
abstract

A description of EPROM failures based on the use of Boolean matrices and operators is offered. It overcomes a number of problems which made previously available theories inapplicable to practical devices, and provides a useful tool for the analysis of test pattern efficiency.


1981 - Reliability problems in TTL-LS devices [Articolo su rivista]
Canali, C.; Fantini, Fausto; Gaviraghi, S.; Senin, A.
abstract

An analysis of the possible failure modes of TTL-LS was carried out, with particular emphasis on long term stability of Schottky diodes, all realized by PtSi-Ti/W-Al metallization system.


1976 - Problemi connessi alla valutazione ed all'impiego di contenitori plastici in applicazioni a vita utile molto lunga [Articolo su rivista]
Basile, L; Fantini, Fausto
abstract

Rimangono seri dubbi che i contenitori plastici possano assicurare l'affidabilità richiesta per un lungo periodo di tempo, in un'ampia varietà di condizioni climatiche. E' questo l'aspetto considerato nel presente lavoro.