• DOI:10.1109/IEDM.1984.190866
• Corpus ID: 12136665

Non-latch-up 1200V 75A bipolar-mode MOSFET with large ASO

@article{Nakagawa1984Nonlatchup17,
  title={Non-latch-up 1200V 75A bipolar-mode MOSFET with large ASO},
  author={Akio Nakagawa and H. Ohashi and Mamoru Kurata and H. Yamaguchi and K. Watanabe},
  journal={1984 International Electron Devices Meeting},
  year={1984},
  pages={860-861}
}

• A. Nakagawa, H. Ohashi, +2 authors K. Watanabe
• Published 1984
• Engineering
• 1984 International Electron Devices Meeting

In 1984 ICSSDM, Kobe, we already reported the development of 1200V, 75A bipolar-mode MOSEs(BIFET[l], or called IGT, COMFET [2,3]), which could turn-off 75Amps drain current with lOOOV applied drain voltage at the elevated temperature, 125 C(see Fig. 1). This paper presents improved BIFETs with non-latch-up structure as well as a large ASO. Figure 2 shows a cross section of a new BIFET. A part of the source layer is periodically eliminated, providing a low resistance bypass for holes to the source electrode without biasing the source-base junction. The maximum drain current was substantially limited by the c annel pinch-off effect before ti reached the increased latchup current level, which was attained by the vertical BIFET structure and the optimized source pattern. Thus, the latch-up mode was not observed under any driving conditions unless gate voltage exceeds 20V. It was found that the latch-up current density JL depends gate width LG through the following equation [I]: JL=Vbi/(LG Rb) ----LG: gate width; Vbi:built-in voltage for sourcebase junct.; Rb:channel to source electrode p-base resistance for unit channel width. New BIFET structure provides a lower Rb, which enables to use a larger LG than the original BIFET with attaining a high latch-up current density. Thus, new BIFETs exhibit low forward voltage regardless of reduced channel width. BIFETs should have a sufficiently large AS0 so that BIFETs can be used as a key switching device in place of bipolar transistors in a power application system. If the external load is caused to be short-circuited due to system failure, drain current is limited only by the device resistance itself with the drain voltage being the same as the external power supply voltage. The device should dissipate a large heat 'until a protection circuit works, reducing gate voltage to zero. Figure 3 shows the measured 25 pec forward conductionAS0 limit. The improved BIFETs can sustainmore than 65Amps drain current with 600V forward voltage drop and 20V gate voltage during 25 gsec, which is sufficient for sensing and device protection. Measured switching AS0 is also included in Fig. 3. Voltage and current density product exceeds 3X105VA/cm2, which suggests avalanche multiplication for a failure cause. Neither snubber nor clamp circuit is necessary for the inductive load switching. Figure 4 shows 48Amps switching waveforms, wherein voltage surge is clamped by the device itself. The electrical characteristics for the improved BIFETs are given in Table. BIFETs are now ready for applications.