Method of making high breakdown voltage twin well device with

Abstract

An FET semiconductor device comprises a doped silicon semiconductor substrate having surface. The substrate being doped with a first type of dopant. An N-well is formed within the surface of the P-substrate. A P-well is formed within the N-well forming a twin well. Field oxide regions are formed on the surface of the substrate located above borders between the wells and regions of the substrate surrounding the wells. A gate electrode structure is formed over the P-well between the field oxide regions. A source region and a drain region are formed in the surface of the substrate. The source region and the drain region are self-aligned with the gate electrode structure with the source region and the drain region being spaced away from the field oxide regions by a gap of greater than or equal to about 0.7 .mu.m.