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We have proposed and analyzed MOSFET-mode operation of ultra-thin wafer PTlGBTs in ISPSD02[1]. The present paper, for the first time, presents analytical theory of MOSFET-mode operation, and shows that the SOA is determined by a mechanism similar to the second breakdown of npn bipolar transistors.demonstrates, for the first time, that the MOSFETmode IGBTs are strongly effective for sofl switching application. The developed MOSFET-mode 9OOV 60A thin wafer Trench Gate PTlGBTs have reduced turn-off loss by 55% at 125OC, compared with the conventional (4" generation) sofl switching PTIGBTs. MOSFET-mode OperationMOSFET-mode operation is defined in such a way that the anode efficiency y is less than yuos, which represents pd(pn +h). The anode efficiency y is defined as the ratio of the hole current over the total current at the n-base n-bufferjunction, being identical to the product of pemitter injection efficiency Y~~ and transport factor in the n-buffer ar. (Please note that y in the present paper is different from the conventional injection efficiency of the p-emitter.)The ywosvalue dynamically changes as the electric field changes inside the device because the mobility p is a function of the electric field. Figure I shows yMos as a function of electric field. IGBTs may change its operation mode as the forward voltage increases and the electric field inside the device increases.The present paper also experimentally 0.5 I 1 g0.4 E f o . 4 1 M;FET-Mode., 1 '1E2 1E3 1E4 1E6.Fig.1 Area for MOSFET-mode operation.In the MOSFET-mode operation, several unique characteristic features are distinguished. The features are very similar to the operation of pure MOSFETs. Elwtcic Field (V/cmcm)

Ultrathin gate dielectrics are important to realize high performance and low-voltage operation CMOS devices. An advanced ultrathin gate dielectric formation process, that is, direct nitridation of silicon and sequential oxidation, is proposed and evaluated to suppress boron penetration and to improve hot-carrier reliability. No boron penetration, longer hot-carrier lifetime and high drain current are achieved in MOSFETs with 2.5nm oxidized nitride gate dielectric.

Absfruct -EM1 noise of IGBTnEGT (Injection Enhancement Gate Transistor) circuit is significantly reduced by introducing a new device design criterion. The design criterion improves d V d d t controllability during the IEGT turn-on transient without sacrificing the featured low saturation voltage of IEGT structure. The perfectly floating p-well region as the criterion prevents the undesirable VGE overshoot and the resultant uncontrollable d V d d t .The design criterion has been applied to a 12OOV ultra thin PT-IEGT, and low noise turn-on characteristics have been experimentally obtained. IEGTs with the new criterion enable low noise operation and precise gate control, which are suitable for active gate drive.