- Email: [email protected]
Power semiconductor devices — continuous development
,;-:
MicroelctronicsJournal27 (1996) 105-107 Copyright © 1996 Published by.Elsevier Science Limited Printed in Great Britain. All rights reserved 0026-2692/96/$15.00
, J'
ELSEVIER
0026-2692(95)00079-8
Power semiconductor devices-- continuous development N. Stojadinovi61 and P. Spirito 2 1Faculty of Electronic Engineering, University of Ni~, Beogradska 14, 18000 Nik, Serbia 2Department of Electronic Engineering, University of Naples, via Claudio 21, 1-80125 Naples, Italy
After recalling the breakthroughs in the area of power semiconductor devices which appeared during the 1980s and their impact on power electronics applications, the present status and future trends in the development of power semiconductor devices are briefly reviewed, and the educational needsfor people engaged in this area are pointed out. The motivation for the publication of this second special issue of the Microelectronics Journal on power microelectronics lies in the awareness that this rapidly growing area is playing an increasingly important role in today's global society, which is becoming more conscious of the need to reduce energy consumption and environmental pollution. We hope that the five feature articles, one review paper and eight research papers selectedfor this special issue will provide suj~cient coverage of all important aspects of power semiconductor devices, including the educational ones, and that this special issue will be useful for all people from academic and industrial environments who actively work in this area.
continuously been added to the existing ones, i.e. power bipolar transistors (BJTs) and thyristors, which at that time had been the workhorses for any power system. The first innovation was the introduction of a control terminal in a thyristor, which resulted in the development of the gate turn-off (GTO) thyristor; the capability of a controlled tumingoff of the device opened new possibilities for the power systems apphcations, which had mainly concerned the converters and inverters. The second innovation, for low voltage applications, was the realization of the power MOSFET as a voltage controlled power device. This innovative device has brought the capabilities of VLSI technology into the area of power devices; the power MOSFET had been, in fact, constituted of a large number of elementary cells like an integrated circuit and it had required more sophisticated technology than a BJT or thyristor.
After a relatively slow growth in the 1960s and 1970s, the field of' power microelectronics experienced a significant evolution in the 1980s, which was essentially driven by innovative concepts and breakthroughs in the area of power semiconductor devices. In fact, starting from the early 1980s, new power devices had
Shortly after these innovations, a new evolutionary device concept was presented, i.e. the merging of conductivity modulation, due to the bipolar operation, with the voltage control of a MOSFET- or JFET-gated device. This new possibility opened up a completely new family of power devices, from which emerged the insulated gate bipolar transistor (IGBT), which
105
N. Stojadinovi6 and P. Spirito/Guest Editorial
combines the voltage control, due to the MOSFET gate, with the capability of high current and voltage ratings, due to the bipolar conductivity in the on-state. Among other new devices which have been presented in the technical literature, such as static induction transistor (SIT), static induction thyristor (SITh) and field controlled thyristor (FCTh), another very promising device appeared to be the MOSFET controlled thyristor (MCT), which again combines the voltage control of a MOSFET gate (both for turn-on and turn-off) with the large current capability and low voltage drop at high voltage ratings, due to the thyristor regenerative action. This innovative scenario in the area of power devices has had a strong impact on the innovation of power systems and circuits, as can be seen by the continuous growth of the major conferences covering different areas from the field of power microelectronics, such as the Power Electronics Specialist Conference (PESC), the European Power Electronics Conference (EPE), the International Symposium on Power Semiconductor Devices and ICs (ISPSD) and the International Seminar of Power Semiconductors (ISPS), as well as by the steady increase of the number of papers presented in the technical literature. Some trends in the field of power microelectronics in the first half of the 1990s and beyond can be noticed. The advantage of a simplified drive circuitry by the voltage control of new MOSFET-gated devices, such as power MOSFET, IGBT and MCT, has pushed system designers to consider, as much as possible, the application of these devices in power systems. Also, different performances of new power devices can give useful choices to design needs for a variety of power applications. As an example for low voltage applications, such as that in switching power supplies, the power MOSFET is replacing the BJT, thus allowing easy drive circuitry and higher frequency
106
operation, which in turn reduce the weight (and the cost) of the power system. For the higher voltage ratings, IGBT is gaining wide acceptance as its performances are steadily increasing (IGBTs rated at 3.3kV are available on the market), while the improvements in GTO still give room for single device applications at higher voltage and current ratings. Finally, for the high power range, MCT is expected, due to the technological efforts put on it, to compete soon with both the IGBT and GTO. The next emerging trend is the application of new devices in power modules, by assembling in a single package several IGBT or MCT chips, along with the sensing and control components for easier use in high power systems. The availability of these new devices with faster switching times and increased raggedness has enhanced the application of new circuit configurations for power conditioning systems, such as resonant and quasi-resonant converters, with soft switching operation and increased frequency operation. Finally, the widespread application of smart power devices and circuits is expected to have a strong impact on the development of power systems for low and medium power applications. After the above-described evolutionary phase of the power microelectronics scenario, current interest is devoted to the improvement of the reliability and performance limits of new devices, as well as to their more efficient application in different power systems. Increasing attention is also being given to the simulation tools, for the devices themselves, as well as for their operation in power systems, in order to understand better their operation and to design more effective systems. Mixed mode analysis of device-circuit interactions is increasingly being developed and electro-thermal models of the device for educational aspects have appeared in order to show the possibilities of the new power devices to the people who will be engaged in both device fabrication and application in power
Microelectronics Journal, Vol. 27, Nos 2-3
systems. Understanding of the physics and behaviour of these rtew power devices cannot rely on the basic knowledge of semiconductor physics in standard courses, and therefore new concepts must be added in order to provide an insight into the operation of MOSFET-gated bipolar devices, such ;is IGBT and MCT, as well as on their operating hmits posed by different physical mechanisms,, some of them being not fully understood so far. Because of the fact that, by bringing ability to control energy using power devices to the existing information processing capability, power microelectronics has been expected to play an increasingly important role in a global society, which is becoming more conscious of the need to reduce energy consumption and environmental pollution, we decided to establish from 19913, the publication of a special issue on porter microelectronics. For the first issue we published the special issue with 11 invited papers written by many of the world-leading authorities from the field of power microelectronics, four of them being extended versions of their papers presented at the European Power Electronics Conference (EPE-MADED'91), held in Firenze, Italy (September 1991). For this special issue we have selected, after rigorous reviewing and revisions, eight research papers devoted to physics, technology, modelling, simulation, design and reliability of power devices, as well as five feature articles devoted to educational issues for power devices, presented at the 2nd International Seminar on Power Semiconductors (ISPS'93), held in Prague, the Czech R.epublic (September 1993). The authorship of these papers (two each from
Germany, France, Serbia, Italy and the UK, and one each from the Czech Repubhc, Poland and Spain) indicates the worldwide recognition which this special issue has gained. We have striven to provide this special issue with an introductory up-to-date review paper, prepared by Dr. Duncan Grant, who is a worldleading authority in the field of power microelectronics. This paper, which forms the backbone of the issue, is intended not only to offer valuable insight into the state-of-the-art, but also to highlight the current trends in power microelectronics with great emphasis on those likely to be just the tip of an iceberg, i.e. mere hints of major trends which will emerge in the second half of the 1990s. We realize that today's power device technology is expanding so rapidly that it can be difficult for a specialist working in one area to keep abreast of developments in other areas of the field. Therefore, to claim that a collection of the papers of this kind, no matter how instructive and seriously written, can be a complete review of the field would be an exaggeration. Nevertheless, we do hope that this special issue of the MicroelectronicsJournal will be of interest to all those from academic and industrial environments who actively work in the area of power semiconductor devices. Finally, we would like to take this opportunity to thank all the reviewers, a list of whom is given at the end of this special issue, for their useful and thorough comments which have led to a significant improvement of the papers' quality.
N. Stojadinovic and P. Spirito Guest Editors
107
MicroelctronicsJournal27 (1996) 105-107 Copyright © 1996 Published by.Elsevier Science Limited Printed in Great Britain. All rights reserved 0026-2692/96/$15.00
, J'
ELSEVIER
0026-2692(95)00079-8
Power semiconductor devices-- continuous development N. Stojadinovi61 and P. Spirito 2 1Faculty of Electronic Engineering, University of Ni~, Beogradska 14, 18000 Nik, Serbia 2Department of Electronic Engineering, University of Naples, via Claudio 21, 1-80125 Naples, Italy
After recalling the breakthroughs in the area of power semiconductor devices which appeared during the 1980s and their impact on power electronics applications, the present status and future trends in the development of power semiconductor devices are briefly reviewed, and the educational needsfor people engaged in this area are pointed out. The motivation for the publication of this second special issue of the Microelectronics Journal on power microelectronics lies in the awareness that this rapidly growing area is playing an increasingly important role in today's global society, which is becoming more conscious of the need to reduce energy consumption and environmental pollution. We hope that the five feature articles, one review paper and eight research papers selectedfor this special issue will provide suj~cient coverage of all important aspects of power semiconductor devices, including the educational ones, and that this special issue will be useful for all people from academic and industrial environments who actively work in this area.
continuously been added to the existing ones, i.e. power bipolar transistors (BJTs) and thyristors, which at that time had been the workhorses for any power system. The first innovation was the introduction of a control terminal in a thyristor, which resulted in the development of the gate turn-off (GTO) thyristor; the capability of a controlled tumingoff of the device opened new possibilities for the power systems apphcations, which had mainly concerned the converters and inverters. The second innovation, for low voltage applications, was the realization of the power MOSFET as a voltage controlled power device. This innovative device has brought the capabilities of VLSI technology into the area of power devices; the power MOSFET had been, in fact, constituted of a large number of elementary cells like an integrated circuit and it had required more sophisticated technology than a BJT or thyristor.
After a relatively slow growth in the 1960s and 1970s, the field of' power microelectronics experienced a significant evolution in the 1980s, which was essentially driven by innovative concepts and breakthroughs in the area of power semiconductor devices. In fact, starting from the early 1980s, new power devices had
Shortly after these innovations, a new evolutionary device concept was presented, i.e. the merging of conductivity modulation, due to the bipolar operation, with the voltage control of a MOSFET- or JFET-gated device. This new possibility opened up a completely new family of power devices, from which emerged the insulated gate bipolar transistor (IGBT), which
105
N. Stojadinovi6 and P. Spirito/Guest Editorial
combines the voltage control, due to the MOSFET gate, with the capability of high current and voltage ratings, due to the bipolar conductivity in the on-state. Among other new devices which have been presented in the technical literature, such as static induction transistor (SIT), static induction thyristor (SITh) and field controlled thyristor (FCTh), another very promising device appeared to be the MOSFET controlled thyristor (MCT), which again combines the voltage control of a MOSFET gate (both for turn-on and turn-off) with the large current capability and low voltage drop at high voltage ratings, due to the thyristor regenerative action. This innovative scenario in the area of power devices has had a strong impact on the innovation of power systems and circuits, as can be seen by the continuous growth of the major conferences covering different areas from the field of power microelectronics, such as the Power Electronics Specialist Conference (PESC), the European Power Electronics Conference (EPE), the International Symposium on Power Semiconductor Devices and ICs (ISPSD) and the International Seminar of Power Semiconductors (ISPS), as well as by the steady increase of the number of papers presented in the technical literature. Some trends in the field of power microelectronics in the first half of the 1990s and beyond can be noticed. The advantage of a simplified drive circuitry by the voltage control of new MOSFET-gated devices, such as power MOSFET, IGBT and MCT, has pushed system designers to consider, as much as possible, the application of these devices in power systems. Also, different performances of new power devices can give useful choices to design needs for a variety of power applications. As an example for low voltage applications, such as that in switching power supplies, the power MOSFET is replacing the BJT, thus allowing easy drive circuitry and higher frequency
106
operation, which in turn reduce the weight (and the cost) of the power system. For the higher voltage ratings, IGBT is gaining wide acceptance as its performances are steadily increasing (IGBTs rated at 3.3kV are available on the market), while the improvements in GTO still give room for single device applications at higher voltage and current ratings. Finally, for the high power range, MCT is expected, due to the technological efforts put on it, to compete soon with both the IGBT and GTO. The next emerging trend is the application of new devices in power modules, by assembling in a single package several IGBT or MCT chips, along with the sensing and control components for easier use in high power systems. The availability of these new devices with faster switching times and increased raggedness has enhanced the application of new circuit configurations for power conditioning systems, such as resonant and quasi-resonant converters, with soft switching operation and increased frequency operation. Finally, the widespread application of smart power devices and circuits is expected to have a strong impact on the development of power systems for low and medium power applications. After the above-described evolutionary phase of the power microelectronics scenario, current interest is devoted to the improvement of the reliability and performance limits of new devices, as well as to their more efficient application in different power systems. Increasing attention is also being given to the simulation tools, for the devices themselves, as well as for their operation in power systems, in order to understand better their operation and to design more effective systems. Mixed mode analysis of device-circuit interactions is increasingly being developed and electro-thermal models of the device for educational aspects have appeared in order to show the possibilities of the new power devices to the people who will be engaged in both device fabrication and application in power
Microelectronics Journal, Vol. 27, Nos 2-3
systems. Understanding of the physics and behaviour of these rtew power devices cannot rely on the basic knowledge of semiconductor physics in standard courses, and therefore new concepts must be added in order to provide an insight into the operation of MOSFET-gated bipolar devices, such ;is IGBT and MCT, as well as on their operating hmits posed by different physical mechanisms,, some of them being not fully understood so far. Because of the fact that, by bringing ability to control energy using power devices to the existing information processing capability, power microelectronics has been expected to play an increasingly important role in a global society, which is becoming more conscious of the need to reduce energy consumption and environmental pollution, we decided to establish from 19913, the publication of a special issue on porter microelectronics. For the first issue we published the special issue with 11 invited papers written by many of the world-leading authorities from the field of power microelectronics, four of them being extended versions of their papers presented at the European Power Electronics Conference (EPE-MADED'91), held in Firenze, Italy (September 1991). For this special issue we have selected, after rigorous reviewing and revisions, eight research papers devoted to physics, technology, modelling, simulation, design and reliability of power devices, as well as five feature articles devoted to educational issues for power devices, presented at the 2nd International Seminar on Power Semiconductors (ISPS'93), held in Prague, the Czech R.epublic (September 1993). The authorship of these papers (two each from
Germany, France, Serbia, Italy and the UK, and one each from the Czech Repubhc, Poland and Spain) indicates the worldwide recognition which this special issue has gained. We have striven to provide this special issue with an introductory up-to-date review paper, prepared by Dr. Duncan Grant, who is a worldleading authority in the field of power microelectronics. This paper, which forms the backbone of the issue, is intended not only to offer valuable insight into the state-of-the-art, but also to highlight the current trends in power microelectronics with great emphasis on those likely to be just the tip of an iceberg, i.e. mere hints of major trends which will emerge in the second half of the 1990s. We realize that today's power device technology is expanding so rapidly that it can be difficult for a specialist working in one area to keep abreast of developments in other areas of the field. Therefore, to claim that a collection of the papers of this kind, no matter how instructive and seriously written, can be a complete review of the field would be an exaggeration. Nevertheless, we do hope that this special issue of the MicroelectronicsJournal will be of interest to all those from academic and industrial environments who actively work in the area of power semiconductor devices. Finally, we would like to take this opportunity to thank all the reviewers, a list of whom is given at the end of this special issue, for their useful and thorough comments which have led to a significant improvement of the papers' quality.
N. Stojadinovic and P. Spirito Guest Editors
107