US 8,076,720 B2 · Trench gate type transistor

Abstract

The invention provides a trench gate type transistor in which the gate leakage current is prevented and the gate capacitance is reduced. A trench is formed in an N− type semiconductor layer. A thin silicon oxide film is formed on a region of the N− type semiconductor layer for the active region of the transistor in the trench. On the other hand, a silicon oxide film which is thicker than the silicon oxide film is formed on a region not for the active region. Furthermore, a leading portion extending from inside the trench onto the outside thereof forms a gate electrode contacting the silicon oxide film. This provides a long distance between the gate electrode at the leading portion and the corner portion of the N− type semiconductor layer, thereby preventing the gate leakage current and reducing the gate capacitance.

Claims9

Dependent claims

A trench gate type transistor comprising:

a semiconductor layer having a trench formed therein;
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 a sidewall of the trench,
the gate insulation film comprising a first gate insulation film having a first thickness in a portion in contact with the body layer and a second gate insulation film having a second thickness larger than the first thickness in a portion covering a top edge portion of the trench where the sidewall of the trench and the top surface of the semiconductor layer meet.

3 more elements

Dependencies are inferred from the claim text.

Trench gate type transistor

Life of this patent

Trench gate type transistor

Life of this patent

Abstract

Claims9