Trench-gate RESURF semiconductor device and manufacturing method
First Claim
Patent Images
1. A method of manufacturing a trench-gate semiconductor device, comprising:
- forming a silicon substrate with an epitaxial layer doped with a first type of dopant, and which defines a device drift region;
etching a gate trench into the substrate;
forming a first portion of a gate oxide against at least side walls of the trench and forming a thicker gate oxide at a bottom of the trench;
implanting a pillar region beneath the gate trench doped with a second type of dopant of opposite type to the first type of dopant;
depositing, doping and annealing a gate electrode in the gate trench;
implanting and annealing a semiconductor body region on each side of the gate trench;
implanting and annealing source regions on each side of the gate trench over the semiconductor body region;
forming a second portion of gate oxide on top of the first portion of gate oxide;
etching the semiconductor body region using the second portion of gate oxide as a mask to form a moat region at the sides of the source regions to form contact openings for contact with the source regions;
implanting and annealing RESURF regions at a base of the moat, wherein the RESURF regions are formed on each side of the gate trench, doped with the second type of dopant of opposite polarity type to the first type of dopant, and extend more deeply into the drift region than the gate trench; and
depositing and patterning a metallisation layer to form source and gate contacts,wherein the pillar region is beneath and in substantial contact with the gate trench and configured and arranged to act as an additional RESURF region and reduce the effective width of the drift region in an area between the RESURF regions and increase gate shielding, andwherein the pillar region is formed to a depth which is at least substantially equal to the depth of the RESURF regions.
12 Assignments
0 Petitions
Accused Products
Abstract
A trench-gate device with lateral RESURF pillars has an additional implant beneath the gate trench. The additional implant reduces the effective width of the semiconductor drift region between the RESURF pillars, and this provides additional gate shielding which improves the electrical characteristics of the device.
28 Citations
12 Claims
-
1. A method of manufacturing a trench-gate semiconductor device, comprising:
-
forming a silicon substrate with an epitaxial layer doped with a first type of dopant, and which defines a device drift region; etching a gate trench into the substrate; forming a first portion of a gate oxide against at least side walls of the trench and forming a thicker gate oxide at a bottom of the trench; implanting a pillar region beneath the gate trench doped with a second type of dopant of opposite type to the first type of dopant; depositing, doping and annealing a gate electrode in the gate trench; implanting and annealing a semiconductor body region on each side of the gate trench; implanting and annealing source regions on each side of the gate trench over the semiconductor body region; forming a second portion of gate oxide on top of the first portion of gate oxide; etching the semiconductor body region using the second portion of gate oxide as a mask to form a moat region at the sides of the source regions to form contact openings for contact with the source regions; implanting and annealing RESURF regions at a base of the moat, wherein the RESURF regions are formed on each side of the gate trench, doped with the second type of dopant of opposite polarity type to the first type of dopant, and extend more deeply into the drift region than the gate trench; and depositing and patterning a metallisation layer to form source and gate contacts, wherein the pillar region is beneath and in substantial contact with the gate trench and configured and arranged to act as an additional RESURF region and reduce the effective width of the drift region in an area between the RESURF regions and increase gate shielding, and wherein the pillar region is formed to a depth which is at least substantially equal to the depth of the RESURF regions. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
-
-
11. A method of manufacturing a trench-gate semiconductor device, comprising:
-
forming a silicon substrate with an epitaxial layer doped with a first type of dopant, and which defines a device drift region; etching a gate trench into the substrate; forming a first portion of a gate oxide against at least side walls of the trench and forming a thicker gate oxide at a bottom of the trench; implanting a pillar region beneath the gate trench doped with a second type of dopant of opposite type to the first type of dopant; depositing, doping and annealing a gate electrode in the gate trench; implanting and annealing a semiconductor body region on each side of the gate trench; implanting and annealing source regions on each side of the gate trench over the semiconductor body region; forming a second portion of gate oxide on top of the first portion of gate oxide; etching the semiconductor body region using the second portion of gate oxide as a mask to form a moat region at the sides of the source regions and contact openings for contact with the source regions; implanting and annealing RESURF regions at a base of the moat; depositing and patterning a metallisation layer to form source and gate contacts; forming an implant region of the second type of dopant at ends of the gate trench to couple the pillar region to the implanted and annealed RESURF regions, wherein the implant region is connected to the source regions and to the pillar region to bias the pillar region at a potential of the source regions, and wherein the pillar region beneath the gate trench is configured and arranged relative to the implanted and annealed RESURF regions to act as an additional RESURF region and reduce the effective width of the drift region between the implanted and annealed RESURF regions and increasing gate shielding.
-
-
12. A method of manufacturing a trench-gate semiconductor device, comprising:
-
etching a gate trench into a silicon substrate having an epitaxial layer, the epitaxial layer being doped with a first type of dopant and defining a device drift region; forming a first portion of a gate oxide against at least side walls of the trench and forming a thicker gate oxide at a bottom of the trench; implanting a pillar region beneath the gate trench doped with a second type of dopant of opposite type to the first type of dopant; forming a gate electrode in the gate trench, a semiconductor body region on each side of the gate trench, and source regions on each side of the gate trench over the semiconductor body region; forming a second portion of gate oxide on top of the first portion of gate oxide, a moat region at the sides of the source regions to form contact openings for contact with the source regions; implanting and annealing RESURF regions at a base of the moat; and forming a metallisation layer to form source and gate contacts, an implant region of the second type of dopant at ends of the gate trench to couple the pillar region to the RESURF regions, and causing the source regions to be connected to the pillar region in order to bias the pillar region at a potential of the source regions, wherein the pillar region implanted beneath the gate trench is configured and arranged with the RESURF regions to act as an additional RESURF region and reduce the effective width of the drift region and increase gate shielding.
-
Specification