Patent ID: 8587087

Claim:
A semiconductor device including an IGBT, the IGBT comprising: (a) a p type collector layer; (b) an n type buffer layer formed over the p type collector layer; (c) an n type base layer formed over the n type buffer layer and having a higher resistance than that of the n type buffer layer; (d) a surface semiconductor layer formed over the n type base layer via a buried insulating film having an opening part and electrically connected to the n type base layer in the opening part; (e) a p type channel forming layer formed in a part of the surface semiconductor layer; (f) a gate insulating film formed on the p type channel forming layer; (g) a p type emitter layer formed in the surface semiconductor layer so as to be electrically connected to the p type channel forming layer and having a higher p type impurity concentration than that of the p type channel forming layer; (h) an n type source layer formed in a part of the surface semiconductor layer and electrically connected to both the p type channel forming layer and the p type emitter layer; (i) a gate electrode formed over the gate insulating film; (j) a collector electrode formed below the p type collector layer and electrically connected to the p type collector layer; and (k) an emitter electrode formed over the p type emitter layer and the n type source layer and electrically connected to the p type emitter layer and the n type source layer, wherein, in a region in which the p type channel forming layer is sandwiched by the buried insulating film and the gate insulating film, a thickness of the p type channel forming layer in the region is 20 nm to 100 nm.