Structure and method for forming laterally extending dielectric layer in a trench-gate FET
First Claim
1. A method of forming a FET, comprising:
- forming a trench in a silicon region;
forming a shield electrode in a bottom portion of the trench, the shield electrode being insulated from adjacent silicon region by a shield dielectric;
forming a nitride etch resistant layer extending over a surface of the silicon region adjacent the trench, along trench sidewalls, and over the shield electrode and the shield dielectric;
forming a silicon nitride layer extending over the nitride etch resistant layer along the surface of the silicon region adjacent the trench, along the trench sidewalls, and over the shield electrode and the shield dielectric;
forming a layer of low temperature oxide (LTO) over the silicon nitride layer such that those portions of the LTO layer extending over the surface of the silicon region adjacent the trench are thicker than the portion of the LTO layer extending over the shield electrode; and
uniformly etching back the LTO layer such that a portion of the silicon nitride layer extending over the shield electrode and along at least a portion of the trench sidewalls becomes exposed while portions of the silicon nitride layer extending over the surface of the silicon region adjacent the trench remain covered by remaining portions of the LTO layer.
7 Assignments
0 Petitions
Accused Products
Abstract
A FET is formed as follows. A trench is formed in a silicon region. A shield electrode is formed in a bottom portion of the trench. The shield electrode is insulated from adjacent silicon region by a shield dielectric. A silicon nitride layer is formed over a surface of the silicon region adjacent the trench, along the trench sidewalls, and over the shield electrode and shield dielectric. A layer of LTO is formed over the silicon nitride layer such that those portions of the LTO layer extending over the surface of the silicon region adjacent the trench are thicker than the portion of the LTO layer extending over the shield electrode. The LTO layer is uniformly etched back such that a portion of the silicon nitride layer becomes exposed while portions of the silicon nitride layer remain covered.
-
Citations
27 Claims
-
1. A method of forming a FET, comprising:
-
forming a trench in a silicon region; forming a shield electrode in a bottom portion of the trench, the shield electrode being insulated from adjacent silicon region by a shield dielectric; forming a nitride etch resistant layer extending over a surface of the silicon region adjacent the trench, along trench sidewalls, and over the shield electrode and the shield dielectric; forming a silicon nitride layer extending over the nitride etch resistant layer along the surface of the silicon region adjacent the trench, along the trench sidewalls, and over the shield electrode and the shield dielectric; forming a layer of low temperature oxide (LTO) over the silicon nitride layer such that those portions of the LTO layer extending over the surface of the silicon region adjacent the trench are thicker than the portion of the LTO layer extending over the shield electrode; and uniformly etching back the LTO layer such that a portion of the silicon nitride layer extending over the shield electrode and along at least a portion of the trench sidewalls becomes exposed while portions of the silicon nitride layer extending over the surface of the silicon region adjacent the trench remain covered by remaining portions of the LTO layer. - View Dependent Claims (2, 3, 4, 5, 6)
-
-
7. A method of forming a FET, comprising:
-
forming a trench in a silicon region; forming a shield electrode in a bottom portion of the trench, the shield electrode being insulated from adjacent silicon region by a shield dielectric; forming an insulating layer extending over a surface of the silicon region adjacent the trench, along trench sidewalls, and over the shield electrode; forming an oxidation barrier layer extending over the insulating layer along the surface of the silicon region adjacent the trench, along the trench sidewalls, and over the shield electrode; forming a protective layer over the oxidation barrier layer inside and outside the trench; partially removing the protective layer such that a portion of the oxidation barrier layer extending at least over the shield electrode becomes exposed and portions of the oxidation barrier layer extending over the surface of the silicon region adjacent the trench remain covered by remaining portions of the protective layer; removing the exposed portion of the oxidation barrier layer from over the shield electrode, wherein removing the exposed portion of the oxidation barrier layer exposes a portion of the insulating layer extending over the shield electrode; and forming a dielectric layer over the shield electrode. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14, 15)
-
-
16. An intermediary of a FET, comprising:
-
a trench extending into a silicon region; a shield electrode recessed in a lower portion of the trench, the shield electrode being insulated from the silicon region by a shield dielectric; an oxidation barrier layer extending over a surface of the silicon region adjacent the trench and along the trench sidewalls but being discontinuous over the shield electrode; an insulating layer extending over the surface of the silicon region adjacent the trench, along the trench sidewalls, and over the shield electrode, the insulating layer being covered by the oxidation barrier layer except for the portion of the insulating layer extending over the shield electrode; and a protective layer extending over all horizontally extending portions of the oxidation barrier layer. - View Dependent Claims (17, 18, 19, 20, 21)
-
-
22. An intermediary of a FET, comprising:
-
a trench extending into a silicon region; an oxidation barrier layer extending over a surface of the silicon region adjacent the trench and along the trench sidewalls but being discontinuous along the trench bottom; an insulating layer extending over the surface of the silicon region adjacent the trench and along the trench sidewalls and bottom, the insulating layer being covered by the oxidation barrier layer except for the portion of the insulating layer extending along the trench bottom; and a protective layer extending over all horizontally extending portions of the oxidation barrier layer. - View Dependent Claims (23, 24, 25, 26, 27)
-
Specification