Permanently on transistor implemented using a double polysilicon layer CMOS process with buried contact

摘要

A permanently-ON MOS transistor comprises silicon source and drain regions of a first conductivity type in a silicon well region of a second conductivity type. A silicon contact region of the first conductivity types is buried in the well region, said contact region contacting said source region and said drain region. A first gate insulating layer is selectively placed over the silicon source and drain regions. A second gate insulating layer is selectively placed over the first gate insulating layer and over the silicon contact region. A polysilicon gate region is placed over the second gate insulating layer.