Power MOS device with conductive contact layer

• US 20090224316A1
• Filed: 03/31/2009
• Published: 09/10/2009
• Est. Priority Date: 02/11/2005
• Status: Active Grant

• Current Assignee: Alpha & Omega Semiconductor, Ltd.
• Original Assignee: Alpha & Omega Semiconductor, Ltd.
• Inventors: Bhalla, Anup, Li, Tiesheng, Lui, Sik
• Granted Patent: US 7,923,774 B2
• Time in Patent Office: Days
• US Class Current: 257/332
• CPC Class Codes: H01L 29/1095 Body region, i.e. base region, of DMOS transistors or IGBTs cell layout H01L29/0696
• CPC Class Codes: H01L 29/4236 within a trench, e.g. trench gate electrode, groove gate electrode
• CPC Class Codes: H01L 29/456 on silicon
• CPC Class Codes: H01L 29/47 Schottky barrier electrodes H01L29/435 takes precedence
• 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 29/7806 the other device being a Schottky barrier diode
• 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

Abstract

A semiconductor device includes a drain, a body disposed over the drain, a source embedded in the body, a gate trench extending through the source and the body into the drain, a gate disposed in the gate trench, a source body contact trench extending through the source into the body, a conductive contact layer disposed along at least a portion of a source body contact trench sidewall and in contact with at least a portion of the source, and a trench filling material disposed in the source body contact trench and overlaying at least a portion of the conductive contact layer.

Claims

1. A semiconductor device comprising:

a drain;

a body disposed over the drain;

a source embedded in the body;

a gate trench extending through the source and the body into the drain;

a gate disposed in the gate trench;

a source body contact trench extending through the source into the body;

a conductive contact layer disposed along at least a portion of a source body contact trench sidewall and in contact with at least a portion of the source; and

a trench filling material disposed in the source body contact trench and overlaying at least a portion of the conductive contact layer.

2. The semiconductor device of claim 1 further comprising an anti-punch through dopant region that is formed in the body, along at least a portion of the source body contact trench, and in contact with the conductive contact layer.

3. The semiconductor device of claim 2, wherein the source body contact trench has a trench wall and a trench bottom, and the anti-punch through dopant region is disposed continuously along the trench wall and the trench bottom.

4. The semiconductor device of claim 2, wherein the source body contact trench has a trench wall and a trench bottom, and the anti-punch through dopant region is disposed along the trench wall but not along at least a portion of the trench bottom.

5. The semiconductor device of claim 4, wherein the contact layer and the drain form a Schottky diode.

6. The semiconductor device of claim 1, further comprising a plug formed in a space in a bottom region of the source body contact trench.

7. The semiconductor device of claim 6, further comprising an anti-punch through dopant region that is formed in the body and along a portion of the source body contact trench in contact with the conductive contact layer, wherein the anti-punch through dopant region does not extend substantially below top surface of the plug.

8. The semiconductor device of claim 6, wherein the plug comprises a conductive material contacting the conductive contact layer.

9. The semiconductor device of claim 6, wherein the plug comprises a dielectric material overlaying a portion of the conductive contact layer.

10. The semiconductor device of claim 6, wherein the conductive contact layer further connects to a contact metal layer disposed on top of the source body contact trench.

11. The semiconductor device of claim 6, wherein the contact layer and the drain form a Schottky diode.

12. The semiconductor device of claim 1, wherein the trench filling material comprising a conductive material that is different from the conductive contact layer.

13. The semiconductor device of claim 12, wherein the conductive contact layer connects to a contact metal layer disposed on top of the trench filling material, and the trench filling material extends over a top surface of the source.

14. The semiconductor device of claim 12, further comprising an anti-punch through dopant region that is formed in the body and along at least a portion of the source body contact trench.

15. The semiconductor device of claim 12, wherein the contact layer and the drain form a Schottky diode.

16. The semiconductor device of claim 15, further comprising an anti-punch through dopant region that is formed in the body and along at least a portion of the source body contact trench and in contact with the conductive contact layer.

17. The semiconductor device of claim 1, wherein the contact layer and the drain form a Schottky diode.

18. The semiconductor device of claim 17, wherein the conductive contact layer further extends over a gate oxide layer in contact with a contact metal layer disposed on top of the trench filling material, and the trench filling material extends over a top surface of the source.

19. The semiconductor device of claim 17, further comprising an anti-punch through dopant region that is formed in the body, along at least a portion of the source body contact trench, and in contact with the conductive contact layer.

20. The semiconductor device of claim 1, wherein the gate has a gate top surface and the source has a source top surface, and the gate top surface extends substantially above the source top surface.

21. The semiconductor device of claim 1, wherein the source body contact trench extends through the body to the drain.

22. The semiconductor device of claim 1, wherein the source body contact trench is formed to have a smooth shape.

23. The semiconductor device of claim 2, wherein the anti-punch through dopant region includes a region heavily doped with body type dopant material.