Semiconductor device with DMOS and bi-polar transistors

摘要

A gate electrode layer is formed opposite to a p type backgate region posed between an n type source region and an n type epitaxial region, with a gate insulating layer interposed therebetween. A sidewall insulating layer is formed to cover a sidewall of the gate electrode layer. A p type backgate region has a relatively shallow p type diffusion region and a relatively deep p type diffusion region. The relatively deep p type diffusion region has a portion overlapping the relatively shallow p type diffusion region, and has its end portion at the substrate surface located directly beneath the sidewall insulating layer. Accordingly, a semiconductor device and a manufacturing method thereof that allow easy control of the threshold voltage of a DMOS transistor and facilitate realization of a rapidly operating bipolar transistor are attained.