Patent ID: 7399677

Claim:
A method for manufacturing a semiconductor device, comprising the steps of: forming a hole having a predetermined depth in a semiconductor layer of a first conductivity type, the semiconductor layer being formed on a semiconductor substrate as constituting a part of a drain region; forming a diffusion source layer in the hole, the diffusion source layer containing impurities of a second conductivity type different from the first conductivity type; forming a source region of the first conductivity type in a region shallower than the depth of the hole in the semiconductor layer; forming a channel region of the second conductivity type in a region deeper than the depth of the source region in the semiconductor layer so as to be disposed between the drain region and the source region; and heating the semiconductor substrate to a first temperature after completing the diffusion source layer forming step to diffuse the impurities of the second conductivity type from the diffusion source layer into the channel region, thereby forming a low resistance region having a conductivity higher than that of the channel region wherein the low resistance region and the drain region are in contact with each other.