Super junction trench power MOSFET device fabrication

• US 9,443,974 B2
• Filed: 08/27/2009
• Issued: 09/13/2016
• Est. Priority Date: 08/27/2009
• Status: Active Grant

• Current Assignee: Vishay Siliconix
• Original Assignee: Vishay Siliconix
• Inventors: Gao, Yang, Terrill, Kyle, Pattanayak, Deva, Chen, Kuo-In, Chau, The-Tu, Shi, Sharon, Chen, Qufei
• Primary Examiner(s): NGUYEN, DUY T V
• Application Number:
  US12/549,190
• Publication Number:
  US 20110053326A1
• Time in Patent Office: 2,574 Days
• Field of Search: 438/270, 257/E21.419
• US Class Current: 1/1
• CPC Class Codes: H01L 29/0634 Multiple reduced surface field (multi-RESURF) structures, e.g. double RESURF, charge compensation, cool, superjunction (SJ), 3D-RESURF, composite buffer (CB) structures
• 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 29/0661 specially adapted for altering the breakdown voltage by removing semiconductor material at, or in the neighbourhood of, a reverse biased junction, e.g. by bevelling, moat etching, depletion etching
• CPC Class Codes: H01L 29/407 Recessed field plates, e.g. trench field plates, buried field plates
• CPC Class Codes: H01L 29/41766 with at least part of the source or drain electrode having contact below the semiconductor surface, e.g. the source or drain electrode formed at least partially in a groove or with inclusions of conductor inside the semiconductor H01L29/41733 - H01L29/41758 take precedence
• CPC Class Codes: H01L 29/42368 the thickness being non-uniform
• 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

Abstract

Methods of fabricating a super junction trench power MOSFET (metal oxide semiconductor field effect transistor) device are described. A column of p-type dopant in the super junction is separated from a first column of n-type dopant by a first column of oxide and from a second column of n-type dopant by a second column of oxide. In an n-channel device, a gate element for the FET is advantageously situated over the column of p-type dopant; and in a p-channel device, a gate element for the FET is advantageously situated over the column of n-type dopant.

Claims

1. A method of fabricating a super junction trench power metal oxide semiconductor field effect transistor (MOSFET) device having a channel of a first type dopant, said method comprising:

forming a column of second type dopant on a substrate of said first type dopant, wherein said substrate is adjacent to a drain electrode;

depositing a layer of oxide on said substrate and on opposite sides of said column of said second type dopant to form a first column of oxide on said substrate and a second column of oxide on said substrate;

forming a first column of said first type dopant on and in contact with said substrate and adjacent said first column of oxide and forming a second column of said first type dopant on and in contact with said substrate and adjacent said second column of oxide, said column of said second type dopant separated from said first and second columns of said first type dopant by said first and second columns of oxide;

forming a gate element for a field effect transistor between said first column of said first type dopant and said second column of said first type dopant and above said column of said second type dopant;

forming a body region of said second type dopant and forming a source region of said first type dopant adjacent to said gate element;

forming a trench that extends in said first column of said first type dopant, wherein said trench extends through said source region and into said body region;

implanting a region of said second type dopant between said trench and said first column of said first type dopant, said region in contact with both said trench and said first column of said first type dopant and said region separating said trench from said first column of said first type dopant; and

depositing source metal to fill said trench, wherein said region of said second type dopant is in contact with said source metal in said trench and separates said source metal in said trench from said first column of said first type dopant, and wherein said body region and said source region are exposed to and in contact with said source metal in said trench.

2. The method of claim 1 further comprising depositing an oxide layer above said column of said second type dopant prior to forming said gate element to separate said column of said second type dopant from said gate element.

3. The method of claim 1 wherein said first type dopant comprises n-type dopant and said second type dopant comprises p-type dopant.

4. The method of claim 1 further comprising forming an electrical connection that electrically shorts said column of said second type dopant to said layer of source metal.

5. The method of claim 4 wherein said column of first type dopant and said column of second type dopant each have a first dimension greater than a second dimension, said first dimension measured in a first direction and said second dimension measured in a second direction that is orthogonal to said first direction, wherein said source metal is electrically shorted to said column of second type dopant in a third direction that is orthogonal to said first direction and said second direction.

6. The method of claim 1 wherein said trench is aligned with the longitudinal axis of said first column of said first type dopant.

7. The method of claim 1 wherein said first type dopant comprises p-type dopant and said second type dopant comprises n-type dopant.

8. The method of claim 1 wherein said trench extends in said first column in the direction of the longitudinal axis of said trench, wherein said region is between said trench and said first column of said first type dopant in said direction of said longitudinal axis.

9. The method of claim 1 wherein said region is wider than said trench.