Trench mosfet with trench tip implants
First Claim
1. A power semiconductor device, comprising:
- a semiconductor body of a first conductivity type;
a channel region of a second conductivity type in said semiconductor body and extending to a first depth within said semiconductor body;
a plurality of trenches along a surface of said semiconductor body, said trenches extending into said channel region to a depth above said first depth, each trench including sidewalls and a bottom;
a tip implant of said first conductivity type formed within said channel region at the bottom of each trench and extending through said channel region beyond said first depth and into said semiconductor body; and
a gate electrode within each of said plurality of trenches.
2 Assignments
0 Petitions
Accused Products
Abstract
A trench type power semiconductor device includes a channel region atop an epitaxially silicon layer and a plurality of shallow gate electrode trenches within the channel region such that the bottom of each trench extends to a distance above the junction defined by the channel region and epitaxially silicon layer. Formed at the bottom of each trench within the channel region are trench tip implants of the same conductivity as the epitaxial silicon layer. The trench tip implants extend through the channel region and into the epitaxially silicon layer. The tips effectively pull up the drift region of the device in a localized fashion. In addition, an insulation layer lines the sidewalls and bottom of each trench such that the insulation layer is thicker along the trench bottoms than along the trench sidewalls. Among other benefits, the shallow trenches, trench tips, and variable trench insulation layer allow for reduced on-state resistance and reduced gate-to-drain charge.
15 Citations
20 Claims
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1. A power semiconductor device, comprising:
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a semiconductor body of a first conductivity type;
a channel region of a second conductivity type in said semiconductor body and extending to a first depth within said semiconductor body;
a plurality of trenches along a surface of said semiconductor body, said trenches extending into said channel region to a depth above said first depth, each trench including sidewalls and a bottom;
a tip implant of said first conductivity type formed within said channel region at the bottom of each trench and extending through said channel region beyond said first depth and into said semiconductor body; and
a gate electrode within each of said plurality of trenches. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method for fabricating a power semiconductor device, comprising the steps of:
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etching a plurality of trenches in a semiconductor body comprising an epitaxially silicon layer of a first conductivity and a channel region of a second conductivity formed atop said epitaxially silicon layer and extending to a first depth within said semiconductor body, wherein each of said plurality of trenches extends into said channel region to a depth above said first depth, each trench including sidewalls and a bottom;
forming a tip implant of said first conductivity type within said channel region at the bottom of each trench such that each tip implant extends through said channel region beyond said first depth and into said epitaxially silicon layer; and
forming a gate electrode within each of said plurality of trenches. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification