Method of making a trench MOSFET with deposited oxide

• US 7,371,641 B2
• Filed: 10/28/2005
• Issued: 05/13/2008
• 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
• Primary Examiner(s): Gurley; Lynne
• Assistant Examiner(s): Gebremariam; Samuel A
• Application Number:
  US11/261,896
• Publication Number:
  US 20060091456A1
• Time in Patent Office: 928 Days
• Field of Search: 438/259, 438/270, 257/330, 257/E29.99
• US Class Current: 438/259
• 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 method for fabricating a power semiconductor device, comprising:

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

depositing an oxide body at the bottom of said trench;

forming a spacer on each sidewall of said trench over said oxide body, said spacers being spaced from one another, and removing a portion of said oxide body not covered by said spacers to form a recess extending partially through said oxide body;

removing said spacers;

growing a gate oxide over said sidewalls;

forming a T-shaped electrode over said oxide body, said electrode filling said recess.

2. The method of claim 1, wherein said forming of said electrode comprises depositing a conductive body inside said trench to fill at least said recess, and removing a portion of said conductive body, thereby forming said T-shaped electrode in said trench.

3. The method of claim 1, further comprising siliciding said semiconductor body and forming a power contact over said silicided portion of said semiconductor body.

4. The method of claim 2, further comprising siliciding a portion of said T-shaped electrode.

5. The method of claim 1, further comprising forming high conductivity regions adjacent said sidewalls of said trench and forming a power contact in electrical contact with said high conductivity regions and said T-shaped electrode.

6. The method of claim 1, wherein said electrode is a field relief electrode.