Off-State Stress Degradation Analysis and Optimization for the High-Voltage SOI-pLEDMOS With Thick Gate Oxide

In this paper, the off-state stress degradation for the high-voltage p-type lateral extended drain MOS (pLEDMOS) based on the silicon-on-insulator (SoI) substrate with the thick gate oxide has been investigated experimentally. It shows that, during the stress, there are interface states and negative oxide-trapped charges at the polygate terminal region, but the negative oxide-trapped charges are identified to be the main degradation mechanism. In addition, because the difference of the depletion widths leads to different current paths depth under two monitor conditions, it has been observed that the degradation of the saturation drain current (I_dsat) is always much more serious than that of the linear drain current (I_dlin). Finally, a novel SoI-pLEDMOS transistor with a reversed doped HV-N-well has been presented to optimize the off-state degradation.