FABRICATION OF SEMICONDUCTOR DEVICE AND SEMICONDUCTOR DEVICE

摘要

PROBLEM TO BE SOLVED: To decrease the number of fabrication steps required for forming a high breakdown strength transistor and an ordinary breakdown strength transistor on the same semiconductor substrate. SOLUTION: An ion implantation mask for forming (N-type source layer 11)/(N-type drain layer 12) is also used for forming a thin oxide film 5. Ion implantation for regulating the threshold voltage is limited to a part of a channel region 15. Since a P-type implantation layer 14 eliminates compensation, lateral diffusion is accelerated in the channel regions of the N-type source layer 11 and N-type drain layer 12 of a high breakdown strength transistor.