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US 12,622,047 B2Granted
Schottky diode integrated into superjunction power MOSFETs
AssigneeAlpha and Omega Semiconductor International LP
InventorsYi Su, Madhur Bobde
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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 formed in an epitaxial layer. Each MOSFET includes source and body regions and a contact trench formed between first and second gate trenches. A region of the epitaxial layer between the gate trenches extends to the top surface of the epitaxial layer. An insulated gate electrode is formed in each gate trench. At least a portion of the contact trench extends from a top surface of the epitaxial layer to a depth that is shallower than the bottom of the body region.
Claims20
A trench metal-oxide-semiconductor field-effect transistor (MOSFET) device, comprising:
- an active cell area having one or more devices each of the one or more devices including
- 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 and second 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 and second 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 a portion of the first and second gate trenches;
- a contact trench between the first gate trench and the second gate trench, wherein the contact trench is aligned to a corresponding P column in the plurality of alternating N columns and P columns, wherein at least a portion of the contact trench extends from a top surface of the epitaxial layer to a depth that is shallower than the bottom of the body region;
- and
- a Schottky diode area having one or more Schottky diodes each of the one or more devices including
- a plurality of alternating N columns and P columns extending in the epitaxial layer above the heavily doped substrate layer forming a superjunction structure,
- first and second Schottky 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 and second Schottky gate trenches;
- a region of the epitaxial layer extending to the top surface of the epitaxial layer between a portion of the first and second gate trenches,
- a Schottky contact trench between the first gate trench and the second gate trench, wherein the Schottky contact trench is aligned to a corresponding P column in the plurality of alternating N columns and P columns, and
- a contact implant formed beneath a bottom of the Schottky contact trench.
12 more elements
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 and second 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 and second 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 a portion of the first and second gate trenches;
- forming a contact trench between the first gate trench and the second gate trench, wherein the contact trench is aligned to corresponding P columns in the plurality of alternating N columns and P columns, wherein a portion of the contact trench extends from a top surface of the epitaxial layer to a depth that is shallower than the bottom of the body region;
- and
- forming a Schottky diode area having one or more Schottky diodes each of the one or more Schottky diodes including
- a plurality of alternating N columns and P columns extending in the epitaxial layer above the heavily doped substrate layer forming a superjunction structure,
- first and second Schottky 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 and second Schottky gate trenches;
- a region of the epitaxial layer extending to the top surface of the epitaxial layer between a portion of the first and second Schottky gate trenches,
- a Schottky contact trench between the first Schottky gate trench and the second Schottky gate trench, wherein the Schottky contact trench is aligned to a corresponding P column in the plurality of alternating N columns and P columns, and
- a contact implant formed beneath a bottom of the Schottky contact trench.
10 more elements
Dependencies are inferred from the claim text.