Trench MOSFET with deposited oxide

• US 20060091456A1
• Filed: 10/28/2005
• Published: 05/04/2006
• Est. Priority Date: 10/29/2004
• Status: Active Grant

• Current Assignee: Infineon Technologies Americas Corp. (Infineon Technologies AG)
• Original Assignee: International Rectifier Corporation (Infineon Technologies AG)
• Inventors: Montgomery, Robert
• Granted Patent: US 7,371,641 B2
• Time in Patent Office: Days
• US Class Current: 257/330
• CPC Class Codes: H01L 29/407 Recessed field plates, e.g. trench field plates, buried field plates
• CPC Class Codes: H01L 29/42368 the thickness being non-uniform
• 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

Abstract

A trench type power semiconductor device which includes deposited rather than grown oxide in the trenches for the electrical isolation of electrodes disposed inside the trenches from the semiconductor body.

Claims

1. A power semiconductor device comprising:

a semiconductor body having a drift region of one conductivity, and a channel region of another conductivity over said drift region;

a gate trench formed in said semiconductor body through at least said channel region, said gate trench including sidewalls and a bottom wall;

an oxide body disposed at the bottom of said trench;

a gate electrode formed over said oxide body; and

gate oxide interposed between said sidewalls of said trench and said gate electrode, wherein said oxide body is less dense than said gate oxide.

2. The power semiconductor device of claim 1, wherein said oxide body is comprised of TEOS.

3. The power semiconductor device of claim 1, wherein said oxide body is deposited and said gate oxide is grown.

4. The power semiconductor device of claim 1, further comprising a field relief trench, said field relief trench including a field oxide body having a recess, and a T-shaped electrode received at least partially in said recess.

5. The power semiconductor device of claim 4, further comprising a power electrode electrically connected to said T-shaped electrode.

6. The power semiconductor device of claim 5, further comprising a silicide body interposed between said semiconductor body and said power electrode.

7. The power semiconductor device of claim 5, further comprising a silicide body interposed between said T-shaped electrode and said power electrode.

8. The power semiconductor device of claim 1, further comprising a field relief trench having a field oxide body, and a field electrode disposed therein, and at least one highly conductive region of the same conductivity as said channel region formed in at least a sidewall thereof, and a power electrode electrically connected to said field electrode and said at least one highly conductive region.

9. The power semiconductor device of claim 1, further comprising an oxide cap disposed over said gate electrode.

10. A method for fabricating a power semiconductor device, comprising:

forming a trench in a semiconductor body, said trench having sidewalls, and a bottom;

depositing an oxide body at the bottom of said trench; and

forming an electrode over said oxide body.

11. The method of claim 10, further comprising growing a gate oxide over said sidewalls prior to forming said electrode.

12. The method of claim 10, further comprising forming a spacer on each sidewall of said trench over said oxide body, said spacer being spaced from one another, and removing portion of said oxide body to form a recess therein.

13. The method of claim 12, further comprising depositing a conductive body inside said trench to fill at least said recess, and removing portion of said conductive body, thereby forming a T-shaped electrode in said trench.

14. The method of claim 10, further comprising forming a field relief trench having a plurality of sidewalls and a bottom, forming another oxide body at said bottom of said field relief trench, forming a spacer on each sidewall of said field relief trench over said another oxide body, said spacers being spaced from one another, and removing portion of said oxide body to form a recess therein.

15. The method of claim 14,.further comprising depositing a conductive body inside said field relief trench to fill at least said recess, and removing portion of said conductive body, thereby forming a T-shaped electrode in said trench.

16. The method of claim 15, further comprising siliciding said semiconductor body and forming a power contact over said silicided portion of said semiconductor body.

17. The method of claim 16, further comprising siliciding a portion of said T-shaped electrode.

18. The method of claim 14, further comprising forming high conductivity region in said sidewalls of said field relief trench and forming a power contact in electrical contact with said high conductivity regions.

19. The method of claim 10, further comprising forming high conductivity region in said sidewalls of said trench and forming a power contact in electrical contact with said high conductivity regions.