Patent ID: 8242557
Filing Date: 2012-08-14
Classification: H01L

Abstract:
1. A trench gate type transistor comprising: a semiconductor layer having a trench formed therein, in plan view of the semiconductor layer, the trench being elongated in a first direction so as to have a first sidewall elongated in the first direction and a second sidewall disposed at an end of the first sidewall and extending in a second direction different from the first direction; a gate insulation film disposed in the trench and extending outside the trench so as to overlie a top surface of the semiconductor layer; a gate electrode disposed on the gate insulation film; and a body layer formed in the semiconductor layer so as to be in contact with the gate insulation film on the first sidewall of the trench, wherein, on the first sidewall of the trench where the body layer is in contact with the gate insulation film, the gate insulation film comprises a first portion having a first thickness on an upper portion of the sidewall of the trench and a second portion having a second thickness on a lower portion of the sidewall of the trench, the second thickness being larger than the first thickness, both the first portion and the second portion of the gate insulation film are in contact with the body layer, and the gate insulation film further comprises a third portion having the second thickness at a bottom of the trench, and wherein, on the second sidewall of the trench, the gate insulation film is made only of the second portion and does not include the first portion that is thinner than the second portion.