Patent ID: 9196720
Filing Date: 2015-11-24
Classification: H01L

Abstract:
1. A semiconductor device comprising: a first conductivity type drain layer; a first conductivity type low-concentration impurity layer which is formed over the drain layer and has lower impurity concentration than the drain layer; a second conductivity type base layer which is located over the low-concentration impurity layer; a gate insulating film formed at an upper portion of a side surface of a first concave portion which is formed in the base layer and has a lower end located in the low-concentration impurity layer; a first lower insulating film which is formed on a bottom surface and a lower portion of the side surface of the first concave portion, is thicker than the gate insulating film, and is connected to the gate insulating film; a gate electrode embedded in the first concave portion; a first conductivity type source layer which is formed in the base layer to be shallower than the base layer and is located next to the first concave portion when seen in a plan view; a second lower insulating film formed on a bottom surface and a lower portion of a side surface of a second concave portion surrounding the first concave portion when seen in a plan view; an upper insulating film which is formed at an upper portion of the side surface of the second concave portion and connected to the second lower insulating film; and an embedded electrode embedded in the second concave portion, wherein a depth of the second concave portion is greater than or equal to 90% and less than or equal to 110% of a depth of the first concave portion, a thickness of the second lower insulating film is greater than or equal to 95% and less than or equal to 105% of a thickness of the first lower insulating film, and the upper insulating film is thicker than the gate insulating film.