An N-channel MOS transistor of a semiconductor device having a high withstand voltage employs a drain structure with a low concentration and a large diffusion depth, which causes a problem in that a sufficiently high withstand voltage cannot be obtained due to a parasitic NPN transistor formed among...http://www.google.com.au/patents/US7161198?utm_source=gb-gplus-sharePatent US7161198 - Semiconductor integrated circuit device having MOS transistor
