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US 2017/0373183 A1Published application
Semiconductor device and manufacturing method thereof
AssigneeRenesas Electronics Corporation
InventorsYasunori YAMASHITA, Koichi ARAI, Kenichi HISADA
Life of this patent
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Abstract
In a semiconductor device, in a gate insulating film which is formed on/over an inner wall of a trench, the film thickness of a part of a gate insulating film formed so as to cover a corner of the trench is made thicker than the film thickness of a part of the gate insulating film part formed on/over a side face of the trench.
Claims12
A semiconductor device comprising:
- a cell region that a power transistor is formed,
- in the cell region,
- a semiconductor substrate,
- a drift layer which is formed over the semiconductor substrate,
- a channel layer which is formed over the drift layer,
- a source region which is formed over the channel layer,
- a trench which passes through the source region and the channel layer and reaches the drift layer,
- a gate insulating film which is formed over an inner wall of the trench, and
- a gate electrode which fills the trench being formed,
- wherein the gate insulating film has
- a first part which is in contact with the channel layer,
- a second part which is contiguous to the first part and is in contact with the source region, and
- a third part which is contiguous to the first part and is in contact with the drift layer,
- wherein the second part includes
- a first film-thickness part which is contiguous to the first part, and
- a second film-thickness part which is contiguous to the first film thickness part, is made thicker than the first film-thickness part and covers a first corner of the trench which is in contact with the source region, and
- wherein the third part includes
- a third film-thickness part which is contiguous to the first part, and
- a fourth film-thickness part which is contiguous to the third film-thickness part, is made thicker than the third film-thickness part and is formed over a bottom face of the trench.
16 more elements
A semiconductor device manufacturing method comprising the steps of:
- (a):
- preparing a semiconductor substrate over which a drift layer is formed;
- (b) forming a channel layer over the drift layer;
- (c) forming a source region over a surface of the channel layer;
- (d) forming a trench which passes through the source region and the channel layer and reaches the drift layer;
- (e) forming a conductor film over a region from an inner wall of the trench to the source region;
- (f) forming an insulating film over the conductor film;
- (g) performing anisotropic etching on the insulating film;
- (h) after the step (g), oxidizing the conductor film which is exposed from the insulating film and thereby forming a second insulating film;
- (i) after the step (h), removing the insulating film;
- (j) after the step (i), removing the conductor film which is not yet oxidized;
- (k) after the step (j), forming a first insulating film over the exposed inner wall of the trench;
- (1) after the step (k), forming a third insulating film over a region from the first insulating film to the second insulating film;
- (m) after the step (1), forming a gate insulating film which includes the first insulating film, the second insulating film and the third insulating film by performing patterning on the third insulating film;
- and
- (n) after the step (m), forming a gate electrode which is in contact with the gate insulating film.
13 more elements
Dependencies are inferred from the claim text.