Semiconductor device

Patent metadata

Field	Value
Publication number	US-2020243641-A1
Application number	US-201816613549-A
Country	US
Kind code	A1
Filing date	May 17, 2018
Priority date	May 17, 2017
Publication date	Jul 30, 2020
Grant date	—

Abstract

A semiconductor device includes a semiconductor layer of a first conductivity type having a first main surface at one side and a second main surface at another side, a trench gate structure including a gate trench formed in the first main surface of the semiconductor layer, and a gate electrode embedded in the gate trench via a gate insulating layer, a trench source structure including a source trench formed deeper than the gate trench and across an interval from the gate trench in the first main surface of the semiconductor layer, a source electrode embedded in the source trench, and a deep well region of a second conductivity type formed in a region of the semiconductor layer along the source trench, a ratio of a depth of the trench source structure with respect to a depth of the trench gate structure being not less than 1.5 and not more than 4.0, a body region of the second conductivity type formed in a region of a surface layer portion of the first main surface of the semiconductor layer between the gate trench and the source trench, a source region of the first conductivity type formed in a surface layer portion of the body region, and a drain electrode connected to the second main surface of the semiconductor layer.

First claim

1 . A semiconductor device comprising:
a semiconductor layer of a first conductivity type having a first main surface at one side and a second main surface at another side; a trench gate structure including a gate trench formed in the first main surface of the semiconductor layer, and a gate electrode embedded in the gate trench via a gate insulating layer; a trench source structure including a source trench formed deeper than the gate trench and formed across an interval from the gate trench in the first main surface of the semiconductor layer, a source electrode embedded in the source trench, and a well region of a second conductivity type formed in a region of the semiconductor layer along the source trench, a ratio of a depth of the trench source structure with respect to a depth of the trench gate structure being not less than 1.5 and not more than 4.0; a body region of the second conductivity type formed in a region of a surface layer portion of the first main surface of the semiconductor layer between the gate trench and the source trench; a source region of the first conductivity type formed in a surface layer portion of the body region; and a drain electrode connected to the second main surface of the semiconductor layer.

2 . The semiconductor device according to claim 1 , wherein an aspect ratio of the trench source structure is greater than an aspect ratio of the trench gate structure.

3 . The semiconductor device according to claim 1 , wherein an aspect ratio of the trench source structure is not less than 0.5 and not more than 18.0.

4 . The semiconductor device according to of claim 1 , wherein a depletion layer spreads from a boundary region between the semiconductor layer and the well region toward a region of the second main surface side than a bottom wall of the gate trench in the semiconductor layer.

5 . The semiconductor device according to claim 4 , wherein the depletion layer overlaps to the bottom wall of the gate trench.

6 . The semiconductor device according to claim 1 , wherein the well region is formed in a region of the semiconductor layer along a side wall of the source trench.

7 . The semiconductor device according to claim 1 , wherein the well region is formed in a region of the semiconductor layer along a bottom wall of the source trench.

8 . The semiconductor device according to claim 1 , wherein the well region is formed continuously in a region of the semiconductor layer along a side wall, a bottom wall, and a corner portion connecting the side wall and the bottom wall of the source trench.

9 . The semiconductor device according to claim 1 , wherein the well region is connected to the body region.

10 . The semiconductor device according to claim 1 , wherein the trench source structure includes a barrier forming layer interposed in a region between the source trench and the source electrode and having a higher potential barrier than a potential barrier between the well region and the source electrode.

11 . The semiconductor device according to claim 10 , wherein the barrier forming layer includes an insulating barrier forming layer made of an insulating material.

12 . The semiconductor device according to claim 10 , wherein the barrier forming layer includes a conductive barrier forming layer made of a conductive material differing from a conductive material of the source electrode.

13 . The semiconductor device according to claim 10 , wherein the barrier forming layer includes an insulating barrier forming layer made of an insulating material, and a conductive barrier forming layer made of a conductive material differing from a conductive material of the source electrode.

14 . The semiconductor device according to claim 10 , wherein the barrier forming layer is formed along a side wall, a bottom wall, and a corner portion connecting the side wall and the bottom wall of the source trench.

15 . The semiconductor device according to claim 1 , further comprising: a contact region of the second conductivity type formed in a region of the semiconductor layer along a side wall of the source trench and having a second conductivity type impurity concentration higher than a second conductivity type impurity concentration of the body region.

16 . The semiconductor device according to claim 1 , further comprising: a contact region of the second conductivity type formed in a region of the semiconductor layer along a bottom wall of the source trench and having a second conductivity type impurity concentration higher than a second conductivity type impurity concentration of the body region.

17 . A semiconductor device comprising:
a semiconductor layer of a first conductivity type having a first main surface at one side and a second main surface at another side; a trench gate structure including a gate trench having a first side wall and a first bottom wall and formed in the first main surface of the semiconductor layer, and a gate electrode embedded in the gate trench via a gate insulating layer; a trench source structure including a source trench having a second side wall and a second bottom wall and formed across an interval from the gate trench in the first main surface of the semiconductor layer, a source electrode embedded in the source trench, and a well region of a second conductivity type formed in a region of the semiconductor layer along the source trench; a body region of the second conductivity type formed in a region of a surface layer portion of the first main surface of the semiconductor layer between the gate trench and the source trench; a source region of the first conductivity type formed in a surface layer portion of the body region; and a drain electrode connected to the second main surface of the semiconductor layer; wherein the second side wall of the source trench includes a first wall portion positioned at the first main surface side of the semiconductor layer with respect to the first bottom wall of the gate trench, and a second wall portion positioned at the second main surface side of the semiconductor layer with respect to the first bottom wall of the gate trench, and the well region includes a first region formed along the first wall portion of the second side wall of the source trench, and a second region formed along the second wall portion of the second side wall of the source trench and having a length greater than a length of the first region in regard to a thickness direction of the semiconductor layer.

Assignees

• Rohm Co Ltd

Inventors

• Nakagawa Minoru
• Nakano Yuki
• Aketa Masatoshi
• Ueno Masaya
• Mori Seigo
• Yamamoto Kenji

Classifications

• H10W72/884

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• H10W90/756

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• H10W90/736

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• H10D64/232

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• H10D62/145

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