A Study of the Influence of Technology on the Negative Gate Capacitance in 1.2kV IGBTs

Due to the widespread usage of 1.2kV IGBTs for low and medium voltage applications, for the first time, this paper investigates the influence of technology on the instability effect of negative gate capacitance (NGC) in IGBT technologies - NPT (non punch-through), PT (punch-through) and FS (field stop). Due to the high density of plasma during forward conduction the p-channel inversion layer formed at the gate oxide/N-drift interface, acts as a low resistance path for holes to flow to the emitter contact. This induces negative charge on the gate electrode and NGC is said to occur when dQG/dVG becomes negative. NGC can influence turn-on and short circuit performance of an IGBT due to accumulation of holes under the gate oxide at high anode voltages. This paper attempts to explain why the FS is the optimum IGBT technology in terms of NGC performance. Moreover, it is shown that the level of gate voltage overshoot can be correlated with N-drift potential under the gate oxide, due to hole- accumulation within the induced p-channel.

[1]  S. Kobayashi,et al.  Progress in development of high power NPT-IGBT module , 1998, Proceedings of the 10th International Symposium on Power Semiconductor Devices and ICs. ISPSD'98 (IEEE Cat. No.98CH36212).

[2]  Ichiro Omura,et al.  IEGT design concept against operation instability and its impact to application , 2000, 12th International Symposium on Power Semiconductor Devices & ICs. Proceedings (Cat. No.00CH37094).

[3]  W. Fichtner,et al.  Oscillation effects in IGBT's related to negative capacitance phenomena , 1999 .

[4]  I. Omura,et al.  IGBT negative gate capacitance and related instability effects , 1997, IEEE Electron Device Letters.

[5]  Y. Minoya,et al.  Analysis of IPM current oscillation under short circuit condition , 1998, Proceedings of the 10th International Symposium on Power Semiconductor Devices and ICs. ISPSD'98 (IEEE Cat. No.98CH36212).

[6]  Ichiro Omura,et al.  IEGT design criterion for reducing EMI noise , 2004, ISPSD 2004.

[7]  S. Musumeci,et al.  Transient behavior of IGBTs submitted to fault under load conditions , 2002, Conference Record of the 2002 IEEE Industry Applications Conference. 37th IAS Annual Meeting (Cat. No.02CH37344).