Threshold voltage degradation under high Vgs and low Vds on 200 V SOI power devices

The hot-carrier degradation behavior of the 200 V lateral insulated gate bipolar transistor and lateral diffused MOS transistor both on SOI substrates (SOI-LIGBT and SOI-LDMOS) under high Vgs and low Vds is experimentally investigated. It is shown that the hot electron injection and trapping into gate oxide in the channel region will domains the degradation, which results in the positive threshold voltage (Vth) shift, however, it is very interesting that the degradation level in SOI-LIGBT device is much more serious than that in SOI-LDMOS device. Finally, an improved method to reduce the Vth degradation of SOI-LIGBT is also presented, which is adding a P-type buried layer under the source to change the hole current path. All the results have been verified by MEDICI simulations.