Patent ID: 7692221

Claim:
A semiconductor device comprising: a substrate, made of a first type semiconductor, having a first surface and a second surface; a base region, made of a second type semiconductor, formed on the first surface of the substrate; gate trenches formed through the base region to reach the substrate; a gate electrode filling the gate trenches, inner walls of the gate trenches being covered with a gate insulating film; an emitter region, made of the second type semiconductor, formed between gate trenches; and an IGBT element including an emitter electrode connected to the emitter region, a collector layer, made of the second type semiconductor, formed on the second surface of the substrate, and a collector electrode connected to the collector layer; wherein: a low breakdown voltage region having a breakdown voltage, which is lower than a breakdown voltage of the IGBT element, is formed on the first surface of the substrate around the IGBT element a carrier collecting region, made of the second type semiconductor and electrically connected to the emitter electrode, is formed in the vicinity of the low breakdown voltage region; an electric field concentration suppressing region is formed on the first surface of the substrate around the base region such that the low breakdown voltage region is disposed between the electric field concentration suppressing region and a region where the IGBT element is formed; and a breakdown voltage of the electric field concentration suppressing region is higher than the breakdown voltage of the low breakdown voltage region and the breakdown voltage of the IGBT element.