Semiconductor device and manufacturing method of the same

• US 20060157779A1
• Filed: 01/19/2006
• Published: 07/20/2006
• Est. Priority Date: 01/20/2005
• Status: Active Grant

• Current Assignee: Renesas Electronics Corporation
• Original Assignee: Renesas Electronics Corporation
• Inventors: Kachi, Tsuyoshi, Hoshino, Yoshinori
• Granted Patent: US 7,679,136 B2
• Time in Patent Office: Days
• US Class Current: 257/330
• CPC Class Codes: H01L 29/0653 adjoining the input or output region of a field-effect device, e.g. the source or drain region
• CPC Class Codes: H01L 29/407 Recessed field plates, e.g. trench field plates, buried field plates
• CPC Class Codes: H01L 29/4236 within a trench, e.g. trench gate electrode, groove gate electrode
• CPC Class Codes: H01L 29/4238 characterised by the surface lay-out
• CPC Class Codes: H01L 29/456 on silicon
• CPC Class Codes: H01L 29/66727 with a step of recessing the source electrode
• CPC Class Codes: H01L 29/66734 with a step of recessing the gate electrode, e.g. to form a trench gate electrode
• CPC Class Codes: H01L 29/7811 with an edge termination structure guard regions per se H01L29/0619; field plates per se H01L29/402
• CPC Class Codes: H01L 29/7813 with trench gate electrode, e.g. UMOS transistors trench gate electrodes per se H01L29/4236
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00

Abstract

The on-resistance of a semiconductor device having a power transistor with a trench gate structure is reduced. A power MIS-FET with a trench gate structure is so formed that the relation expressed as 0≦b≦a holds, where a is the distance between an end of an interlayer insulating layer over the upper face of a semiconductor region for source and the end (position on the periphery of a trench) of the upper face of the semiconductor region for source farther from the gate electrode; and b is the length of the overlap between the interlayer insulating layer and the upper face of the semiconductor region for source. (b is the distance between the position of the end of the interlayer insulating layer over the upper face of the semiconductor region for source and position on the periphery of a trench). As a result, the area of contact between source pads and the semiconductor regions for source is increased, and further the distance between the source pads and a channel forming region can be shortened. Therefore, the on-resistance of the power MIS-FET with a trench gate structure can be reduced.

Claims

1. A semiconductor device having a field-effect transistor with a trench gate structure on a semiconductor substrate, the semiconductor substrate having a first main surface and a second main surface on the reverse side thereof,

the field-effect transistor with a trench gate structure comprising:

a source region of first conductivity type, provided on the first main surface of the semiconductor substrate;

a drain region of the first conductivity type, provided on the second main surface of the semiconductor substrate;

a channel forming region provided between the source region and the drain region of the semiconductor substrate;

a first trench that is extended in a direction orthogonal to the first main surface of the semiconductor substrate so that the first trench is extended from the first main surface of the semiconductor substrate, penetrates the source region and the channel forming region, and is terminated at the drain region;

a gate insulating layer formed in the first trench;

a gate electrode provided in the first trench via the gate insulating layer;

an interlayer insulating layer provided over the gate electrode; and

a source electrode that is provided over the first main surface of the semiconductor substrate with the interlayer insulating layer in-between, and is brought into contact with and electrically connected with the upper face of the source region, exposed from the interlayer insulating layer,

wherein the upper face of the gate electrode is formed at a level lower than the first main surface of the semiconductor substrate, and

wherein, letting the distance between an end of the interlayer insulating layer over the upper face of the source region and the end of the upper face of the source region farther from the first gate electrode be “

a” and

letting the length of the overlap between the interlayer insulating layer and the upper face of the source region be “

b”

, b≦

a.

2. The semiconductor device according to claim 1,

wherein the length b of the overlap between the interlayer insulating layer and the upper face of the source region is equal to or greater than 0.

3. The semiconductor device according to claim 1,

wherein an electrode is provided in the first trench via a first insulating layer,

wherein the gate electrode is formed above the electrode, and

wherein a second insulating layer is formed between the electrode and the gate electrode, and the electrode and the gate electrode are insulated from each other.

4. The semiconductor device according to claim 3,

wherein the electrode is electrically connected with source potential.

5. The semiconductor device according to claim 1,

wherein a plurality of the first trenches and a plurality of the gate electrodes are provided in the first main surface of the semiconductor substrate, and t-he adjoining pitch of adjoining gate electrodes is 1.0 μ

m or less.

6. The semiconductor device according to claim 1,

wherein the first main surface of the semiconductor substrate is formed with a second trench extended in a direction orthogonal to the first main surface of the semiconductor substrate so that the second trench is extended from the upper face of the source region, exposed from the interlayer insulating layer, penetrates the source region, and is terminated at the channel forming region, and

wherein the source electrode is brought into contact with and electrically connected with the source region and the channel forming region through the second trench.

7. The semiconductor device according to claim 1,

wherein the field-effect transistor with a trench gate structure is an n channel-type field-effect transistor.

8. A semiconductor device having a field-effect transistor with a trench gate structure on a semiconductor substrate, the semiconductor substrate having a first main surface and a second main surface on the reverse side thereof,

the field-effect transistor with a trench gate structure comprising:

a source region of first conductivity type, provided on the first main surface of the semiconductor substrate;

a drain region of the first conductivity type, provided on the second main surface of the semiconductor substrate;

a channel forming region provided between the source region and the drain region of the semiconductor substrate;

a first trench extended in a direction orthogonal to the first main surface of the semiconductor substrate so that the first trench is extended from the first main surface of the semiconductor substrate, penetrates the source region and the channel forming region, and is terminated at the drain region;

a gate insulating layer formed in the first trench;

a gate electrode provided in the first trench via the gate insulating layer;

an interlayer insulating layer that is provided over the gate electrode; and

a source electrode that is provided over the first main surface of the semiconductor substrate with the interlayer insulating layer in-between, and is brought into contact with and electrically connected with the upper face of the source region, exposed from the interlayer insulating layer, and

wherein a cutoff trench is provided between an end of a source region on the periphery of a group of a plurality of cells of the field-effect transistor with a trench gate structure and an end of an insulating layer for isolation provided outside the end of the source region on the periphery of the group of a plurality of the cells.

9. The semiconductor device according to claim 8,

wherein the cutoff trench is so provided that the cutoff trench intersects the first trench in the field-effect transistor with a trench gate structure.

10. The semiconductor device according to claim 8,

wherein the first trench in the field-effect transistor with a trench gate structure is so formed that the first trench is extended in a first direction along the first main surface of the semiconductor substrate, and

wherein a plurality of the first trenches extended in the first direction are disposed side by side in a second direction orthogonal to the first direction.

11. The semiconductor device according to claim 10,

wherein the cutoff trench is provided at both ends of a plurality of the first trenches in the first direction so that the cutoff trenches intersect the first trenches.

12. The semiconductor device according to claim 8,

wherein an electrode is provided in the first trenches via a first insulating layer,

wherein the gate electrode is formed above the electrode, and

wherein a second insulating layer is formed between the electrode and the gate electrode, and the electrode and the gate electrode are insulated from each other.

13. The semiconductor device according to claim 12,

wherein the electrode is electrically connected with source potential.

14. The semiconductor device according to claim 12,

wherein the first insulating layer is thicker than the gate insulating layer.

15. The semiconductor device according to claim 12,

wherein the first insulating layer and the insulating layer for isolation are comprised of an insulating layer formed in one and the same process.

16. A manufacturing method of a semiconductor device having a field-effect transistor with a trench gate structure in an element formation region of a semiconductor substrate having a first main surface and a second main surface on the reverse side thereof, comprising the steps of:

(a) preparing the semiconductor substrate;

(b) forming a first trench in a first main surface of the semiconductor substrate which first trench is extended in a direction orthogonal to the first main surface;

(c) forming a first insulating layer over the first main surface of the semiconductor substrate and the inner surface of the first trench;

(d) depositing a first conductor layer over the first main surface of the semiconductor substrate and in the first trench;

(e) removing part of the first conductor layer so that part of the first conductor layer is left in the first trench in an element formation region in the first main surface of the semiconductor substrate, and thereby forming an electrode comprised of the first conductor layer in the first trench;

(f) removing part of the first insulating layer in the element formation region, and thereby forming an insulating layer for isolation comprised of the first insulating layer in an isolation region of the semiconductor substrate;

(g) forming a gate insulating film over the first main surface of the semiconductor substrate and the inner surface of the first trench;

(h) depositing a second conductor layer over the first main surface of the semiconductor substrate and in the first trench;

(i) removing part of the second conductor layer so that part of the second conductor layer is left in the first trench in the element formation region in the first main surface of the semiconductor substrate, and thereby forming a gate electrode comprised of the second conductor layer in the first trench;

(j) implanting a desired impurity on the first main surface of the semiconductor substrate using the insulating layer for isolation as a mask, and thereby forming a channel forming region of the field-effect transistor with a trench gate structure; and

(k) implanting a desired impurity on the first main surface of the semiconductor substrate using the insulating layer for isolation as a mask, and thereby forming a source region of the field-effect transistor with a trench gate structure,

wherein in the step of (b), the first trench for element in which the gate electrode of the field-effect transistor with the trench gate structure is to be buried is formed, and further a cutoff trench is formed between an end of the source region in the element formation region and an end of the insulating layer for isolation.

17. The manufacturing method of a semiconductor device according to claim 16,

wherein the cutoff trench is so formed that the cutoff trench intersects the first trench for element.

18. The manufacturing method of a semiconductor device according to claim 16,

wherein the first trench for element is so formed that the first trench is extended in a first direction along the first main surface of the semiconductor substrate, and

wherein a plurality of the first trenches for element extended in the first direction are disposed side by side in a second direction orthogonal to the first direction.

19. The manufacturing method of a semiconductor device according to claim 18,

wherein the cutoff trench is formed at both ends of the first trench for element in the first direction so that the cutoff trench intersects the first trench for element.

20. The manufacturing method of a semiconductor device according to claim 16, comprising the step of:

forming an electrode in the first trench so that the electrode is insulated from the gate electrode by a second insulating layer.

21. The manufacturing method of a semiconductor device according to claim 20,

wherein the electrode is electrically connected with source potential.

22. The manufacturing method of a semiconductor device according to claim 16,

wherein the first insulating layer is thicker than the gate insulating layer.

23. The manufacturing method of a semiconductor device according to claim 16,

wherein in the step of (e), part of the first conductor layer is removed by etching with a mask applied to lead-out regions in the first conductor layer, and the electrode comprised of the first conductor layer is thereby formed in the first trench.