Schottky diode integrated into superjunction power MOSFETs
AssigneeAlpha and Omega Semiconductor (Cayman) Ltd.
InventorsYi Su, Madhur Bobde
Life of this patent
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Abstract
A trench metal-oxide-semiconductor field-effect transistor (MOSFET) device comprises an active cell area including a plurality of superjunction trench power MOSFETs, and a Schottky diode area including a plurality of Schottky diodes formed in the drift region having the superjunction structure. Each of the integrated Schottky diodes includes a Schottky contact between a lightly doped semiconductor layer and a metallic layer.
Claims20
A trench metal-oxide-semiconductor field-effect transistor (MOSFET) device, comprising:
- a plurality of alternating N columns and P columns extending in an epitaxial layer above a heavily doped substrate layer forming a superjunction structure;
- first, second, third and fourth gate trenches extending from a top surface of the epitaxial layer into the N columns of the superjunction structure;
- an insulated gate electrode formed in each of the first, second third, and fourth gate trenches;
- a source region and a body region formed between the first and second gate trenches, wherein a bottom of the body region reaches a top of a P column in the plurality of alternating N columns and P columns;
- a region of the epitaxial layer extending to the top surface of the epitaxial layer between the third and fourth gate trenches;
- a first contact trench between the first gate trench and the second gate trench and a second contact trench between the third gate trench and the fourth gate trench, wherein the first contact trench and the second contact trench are aligned to corresponding P columns in the plurality of alternating N columns and P columns, wherein the second contact trench extends from a top surface of the epitaxial layer to a depth that is shallower than the bottom of the body region.
A method of fabricating a trench metal-oxide-semiconductor field-effect transistor (MOSFET) device, the method comprising:
- forming a plurality of alternating N columns and P columns extending in an epitaxial layer above a heavily doped substrate layer forming a superjunction structure;
- forming first, second, third and fourth gate trenches from a top surface of the epitaxial layer that extend into the N columns of the superjunction structure;
- forming an insulated gate electrode in each of the first, second third, and fourth gate trenches;
- forming a source region and a body region between the first and second gate trenches, wherein a bottom of the body region reaches a top of a P column in the plurality of alternating N columns and P columns, wherein a region of the epitaxial layer extends to the top surface of the epitaxial layer between the third and fourth gate trenches;
- forming a first contact trench between the first gate trench and the second gate trench and a second contact trench between the third gate trench and the fourth gate trench, wherein the first contact trench and the second contact trench are aligned to corresponding P columns in the plurality of alternating N columns and P columns, wherein the second contact trench extends from a top surface of the epitaxial layer to a depth that is shallower than the bottom of the body region.
Dependencies are inferred from the claim text.