Mauro Ciappa - Academia.edu (original) (raw)
Papers by Mauro Ciappa
The compact model development of a 6,5 kV field-stop IGBT module is presented. In particular, the... more The compact model development of a 6,5 kV field-stop IGBT module is presented. In particular, the model considers the realistic interconnection of IGBTs and anti-parallel diodes found in commercial modules, providing, next to semiconductor physics, an accurate description of electro-magnetic (EM) phenomena associated with the package and layout. A selection of simulation examples demonstrates the usefulness of the proposed solution.
Applied Physics Letters, Aug 20, 2001
Dopant profiles in n-type 6H–SiC samples implanted with N+ ions have been measured by scanning ca... more Dopant profiles in n-type 6H–SiC samples implanted with N+ ions have been measured by scanning capacitance microscopy on cross-sectioned samples. The obtained carrier profiles have been accurately quantified by calculating a complete set of capacitance-to-voltage curves by simulation of the measurement setup, followed by the extraction of the system response characteristic as a function of the local carrier concentration. The discrepancy observed to occur between the scanning capacitance microscopy data and the corresponding secondary ions mass spectroscopy profiles is explained by the fact that the scanning capacitance microscopy is sensitive on the local concentration of free carriers, which is on the local concentration of electrically activated dopant ions.
PESC record, Jun 1, 2008
As the integration level of power electronics equipment increases, the coupling between multi-dom... more As the integration level of power electronics equipment increases, the coupling between multi-domain physical effects becomes more and more relevant for design optimization. At the same time, virtual analysis capability acquires a critical importance and is conditioned by the achievement of an adequate compromise between accuracy and computational effort. This paper proposes the compact model development of a 6.5 kV
Microelectronics Reliability, Jun 1, 1999
This paper proposes the compact model development of a 6.5 kV field-stop IGBT module, for use in ... more This paper proposes the compact model development of a 6.5 kV field-stop IGBT module, for use in a circuit simulation environment. The model considers the realistic connection of IGBT-diode pairs: the description of semiconductor physics is coupled with self-heating effects; electro-magnetic phenomena associated with the package and layout are also taken into account. A selection of simulation examples demonstrates the
Microelectronics Reliability, Sep 1, 2007
Journal of vacuum science & technology, 2004
Journal of vacuum science & technology, May 1, 2002
Diamond-coated cantilevers have been used for scanning capacitance microscopy (SCM) as an alterna... more Diamond-coated cantilevers have been used for scanning capacitance microscopy (SCM) as an alternative for metal-coated cantilevers in order to improve the stability of probes. It is shown that the diamond-coated probes produce adequate intensity of dC signal and high contrast for both p-type and n-type silicon samples and also provide superior endurance characteristics to metal-coated probes. Due to the robustness of the diamond-coated probes, we are able to evaluate the reproducibility of measurements and the homogeneity of the ultrathin oxide for both dry oxidation (heated up to 300 °C in air under ultraviolet illumination) and wet oxidation (immersed into a hydrogen peroxide solution at 70 °C). The dry oxidation shows better reproducibility, while the wet oxidation shows better homogeneity. Finally, comparison of SCM with secondary ion mass spectrometry measurement shows that diamond-coated probes can be used at least for one-dimensional quantitative SCM measurements without any significant effect of depletion in the diamond-coated tip itself.
Quality and Reliability Engineering International, Jul 1, 1996
Catastrophic burn-out occurring during power-cycling of insulated gate bipolar transistor (IGBT) ... more Catastrophic burn-out occurring during power-cycling of insulated gate bipolar transistor (IGBT) multichip modules has been observed to arise as a secondary failure mechanism caused by the lifting of the emitter aluminium bonding wires. In fact, the successive lift-off of the aluminium wires turns in a current crowding through few IGBT cells with consequent triggering of the internal parasitic thyristor-structure. Based on failure analysis data, this paper presents an exaustive description of the symptoms and a simple qualitative model for the time-dependent lift-off of aluminium bond wires in IGBT modules. This power-cycling induced failure mechanism (occurring in the field and during accelerated tests) is described in terms of plastic deformation of the aluminium interconnections (bond wires and chip-metallization) during pulsed operation. Some practical conclusions are finally drawn for power cycle testing and for optimal thermal design.
Bond wire lift-off caused by low-cycle fatigue is one among the dominant failure mechanisms of mo... more Bond wire lift-off caused by low-cycle fatigue is one among the dominant failure mechanisms of modern high power Insulated Gate Bipolar Transistors multichip modules used in traction applications. A model is proposed which is calibrated basing on data from accelerated tests and which predicts quantitatively the lifetime of devices submitted to cyclic loads as they are encountered in current converters
Microelectronics Reliability, Apr 1, 2002
EDFA Technical Articles, May 1, 2007
Dopant profiles in submicron silicon devices are typically measured using scanning probe techniqu... more Dopant profiles in submicron silicon devices are typically measured using scanning probe techniques. A new SEM-based method has recently emerged, however, that could prove to be a more powerful tool for quantitative dopant imaging. This article discusses the measurement physics of secondary electron potential contrast imaging and assesses its capabilities based on the analysis of SiC power transistors, vertical cavity surface emitting lasers, and quantum well devices.
Microelectronics Reliability, Mar 1, 2016
Abstract Current sharing during short circuit events of types I and II has been investigated by e... more Abstract Current sharing during short circuit events of types I and II has been investigated by electro-thermal compact simulation of semiconductor devices paralleled in a 650 V power module. The response of silicon IGBTs has been compared to that of silicon carbide MOSFETs. The study of current unbalance due to symmetrical and asymmetrical interconnect topologies has been followed by isothermal and full electro-thermal simulation of the power modules. It has been shown that replacing in the simulation the active devices within the module by resistors leads to misleading results, because the current unbalance under short circuit conditions is mainly due to the difference in the gate-source/gate-emitter voltage among the individual paralleled devices. Finally, it has been demonstrated that in the investigated power modules, self-heating contributes to the mitigation of current unbalance.
The susceptibility to terrestrial cosmic rays (TCR) of power devices is strongly correlated to th... more The susceptibility to terrestrial cosmic rays (TCR) of power devices is strongly correlated to the peak of the local electric field, thus to the resulting local carriers' multiplication. In this paper, the soft gamma radiation from an Am241 source is used to characterize the pre-breakdown carriers' multiplication in SiC MOSFETs as a function of the applied blocking bias. The resulting multiplication levels are then compared to TCR failure rate literature data assessed by neutron irradiation.
Microelectronics Reliability, Sep 1, 2019
The limits of the traditional experiment approach to extract resistivity in junction-isolated sam... more The limits of the traditional experiment approach to extract resistivity in junction-isolated samples are discussed basing both on physical simulations and on extensive experimental data. Several optimization criteria to design van der Pauw resistors and a related characterization procedure are proposed and experimentally validated in order to extend the extraction of the resistivity up to 500°C.
Microelectronics Reliability, Aug 1, 2008
This paper deals with a novel simulation approach, which enables to take into consideration at th... more This paper deals with a novel simulation approach, which enables to take into consideration at the same time local and global effects that are not easily simulated by the traditional techniques based on finite elements. The proposed method combines physics-based compact models of semiconductor devices with a distributed three-dimensional description of the thermal problem within a unified simulation environment. The performance of the new approach is demonstrated in the case of the simulation of thermal instabilities, which undermines the reliability of high power IGBTs.
The compact model development of a 6,5 kV field-stop IGBT module is presented. In particular, the... more The compact model development of a 6,5 kV field-stop IGBT module is presented. In particular, the model considers the realistic interconnection of IGBTs and anti-parallel diodes found in commercial modules, providing, next to semiconductor physics, an accurate description of electro-magnetic (EM) phenomena associated with the package and layout. A selection of simulation examples demonstrates the usefulness of the proposed solution.
Applied Physics Letters, Aug 20, 2001
Dopant profiles in n-type 6H–SiC samples implanted with N+ ions have been measured by scanning ca... more Dopant profiles in n-type 6H–SiC samples implanted with N+ ions have been measured by scanning capacitance microscopy on cross-sectioned samples. The obtained carrier profiles have been accurately quantified by calculating a complete set of capacitance-to-voltage curves by simulation of the measurement setup, followed by the extraction of the system response characteristic as a function of the local carrier concentration. The discrepancy observed to occur between the scanning capacitance microscopy data and the corresponding secondary ions mass spectroscopy profiles is explained by the fact that the scanning capacitance microscopy is sensitive on the local concentration of free carriers, which is on the local concentration of electrically activated dopant ions.
PESC record, Jun 1, 2008
As the integration level of power electronics equipment increases, the coupling between multi-dom... more As the integration level of power electronics equipment increases, the coupling between multi-domain physical effects becomes more and more relevant for design optimization. At the same time, virtual analysis capability acquires a critical importance and is conditioned by the achievement of an adequate compromise between accuracy and computational effort. This paper proposes the compact model development of a 6.5 kV
Microelectronics Reliability, Jun 1, 1999
This paper proposes the compact model development of a 6.5 kV field-stop IGBT module, for use in ... more This paper proposes the compact model development of a 6.5 kV field-stop IGBT module, for use in a circuit simulation environment. The model considers the realistic connection of IGBT-diode pairs: the description of semiconductor physics is coupled with self-heating effects; electro-magnetic phenomena associated with the package and layout are also taken into account. A selection of simulation examples demonstrates the
Microelectronics Reliability, Sep 1, 2007
Journal of vacuum science & technology, 2004
Journal of vacuum science & technology, May 1, 2002
Diamond-coated cantilevers have been used for scanning capacitance microscopy (SCM) as an alterna... more Diamond-coated cantilevers have been used for scanning capacitance microscopy (SCM) as an alternative for metal-coated cantilevers in order to improve the stability of probes. It is shown that the diamond-coated probes produce adequate intensity of dC signal and high contrast for both p-type and n-type silicon samples and also provide superior endurance characteristics to metal-coated probes. Due to the robustness of the diamond-coated probes, we are able to evaluate the reproducibility of measurements and the homogeneity of the ultrathin oxide for both dry oxidation (heated up to 300 °C in air under ultraviolet illumination) and wet oxidation (immersed into a hydrogen peroxide solution at 70 °C). The dry oxidation shows better reproducibility, while the wet oxidation shows better homogeneity. Finally, comparison of SCM with secondary ion mass spectrometry measurement shows that diamond-coated probes can be used at least for one-dimensional quantitative SCM measurements without any significant effect of depletion in the diamond-coated tip itself.
Quality and Reliability Engineering International, Jul 1, 1996
Catastrophic burn-out occurring during power-cycling of insulated gate bipolar transistor (IGBT) ... more Catastrophic burn-out occurring during power-cycling of insulated gate bipolar transistor (IGBT) multichip modules has been observed to arise as a secondary failure mechanism caused by the lifting of the emitter aluminium bonding wires. In fact, the successive lift-off of the aluminium wires turns in a current crowding through few IGBT cells with consequent triggering of the internal parasitic thyristor-structure. Based on failure analysis data, this paper presents an exaustive description of the symptoms and a simple qualitative model for the time-dependent lift-off of aluminium bond wires in IGBT modules. This power-cycling induced failure mechanism (occurring in the field and during accelerated tests) is described in terms of plastic deformation of the aluminium interconnections (bond wires and chip-metallization) during pulsed operation. Some practical conclusions are finally drawn for power cycle testing and for optimal thermal design.
Bond wire lift-off caused by low-cycle fatigue is one among the dominant failure mechanisms of mo... more Bond wire lift-off caused by low-cycle fatigue is one among the dominant failure mechanisms of modern high power Insulated Gate Bipolar Transistors multichip modules used in traction applications. A model is proposed which is calibrated basing on data from accelerated tests and which predicts quantitatively the lifetime of devices submitted to cyclic loads as they are encountered in current converters
Microelectronics Reliability, Apr 1, 2002
EDFA Technical Articles, May 1, 2007
Dopant profiles in submicron silicon devices are typically measured using scanning probe techniqu... more Dopant profiles in submicron silicon devices are typically measured using scanning probe techniques. A new SEM-based method has recently emerged, however, that could prove to be a more powerful tool for quantitative dopant imaging. This article discusses the measurement physics of secondary electron potential contrast imaging and assesses its capabilities based on the analysis of SiC power transistors, vertical cavity surface emitting lasers, and quantum well devices.
Microelectronics Reliability, Mar 1, 2016
Abstract Current sharing during short circuit events of types I and II has been investigated by e... more Abstract Current sharing during short circuit events of types I and II has been investigated by electro-thermal compact simulation of semiconductor devices paralleled in a 650 V power module. The response of silicon IGBTs has been compared to that of silicon carbide MOSFETs. The study of current unbalance due to symmetrical and asymmetrical interconnect topologies has been followed by isothermal and full electro-thermal simulation of the power modules. It has been shown that replacing in the simulation the active devices within the module by resistors leads to misleading results, because the current unbalance under short circuit conditions is mainly due to the difference in the gate-source/gate-emitter voltage among the individual paralleled devices. Finally, it has been demonstrated that in the investigated power modules, self-heating contributes to the mitigation of current unbalance.
The susceptibility to terrestrial cosmic rays (TCR) of power devices is strongly correlated to th... more The susceptibility to terrestrial cosmic rays (TCR) of power devices is strongly correlated to the peak of the local electric field, thus to the resulting local carriers' multiplication. In this paper, the soft gamma radiation from an Am241 source is used to characterize the pre-breakdown carriers' multiplication in SiC MOSFETs as a function of the applied blocking bias. The resulting multiplication levels are then compared to TCR failure rate literature data assessed by neutron irradiation.
Microelectronics Reliability, Sep 1, 2019
The limits of the traditional experiment approach to extract resistivity in junction-isolated sam... more The limits of the traditional experiment approach to extract resistivity in junction-isolated samples are discussed basing both on physical simulations and on extensive experimental data. Several optimization criteria to design van der Pauw resistors and a related characterization procedure are proposed and experimentally validated in order to extend the extraction of the resistivity up to 500°C.
Microelectronics Reliability, Aug 1, 2008
This paper deals with a novel simulation approach, which enables to take into consideration at th... more This paper deals with a novel simulation approach, which enables to take into consideration at the same time local and global effects that are not easily simulated by the traditional techniques based on finite elements. The proposed method combines physics-based compact models of semiconductor devices with a distributed three-dimensional description of the thermal problem within a unified simulation environment. The performance of the new approach is demonstrated in the case of the simulation of thermal instabilities, which undermines the reliability of high power IGBTs.