Method to improve the breakdown voltage of P-channel devices

摘要

A P-channel MOS device having an elevated breakdown voltage is created without increasing device size or requiring additional fabrication steps. During the P-field implant step, P type dopant is implanted into regions of the silicon expected to lie along the silicon-silicon dioxide interface after silicon dioxide growth. P type dopant implanted in this manner counteracts the effect of phosphorous accumulation at the silicon-silicon dioxide interface due to segregation of N type dopant during subsequent silicon dioxide growth steps