Grooved DMOS process with varying gate dielectric thickness
First Claim
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1. A method of making a semiconductor device comprising the steps of:
- providing a first region of semiconductor material having a first conductivity type;
forming a second region of semiconductor material having a second conductivity type, overlying said first region;
forming a first groove, said first groove extending through said second and third regions and into said first region so that a first portion of said third region and a first portion of said second region lie on at least one side of said first groove;
lining said first groove with a dielectric material thereby forming a second, inner groove, having a first portion of said dielectric material of a predetermined thickness on a sidewall of said first groove thicker than a second portion thereof of a predetermined thickness on said sidewall of said first groove, with the first portion thereof closer to the depth of the first groove than the second portion thereof;
filling the depth of said second, inner groove with a conductive material; and
forming an insulating layer over the device resulting from the preceding steps.
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Abstract
Disclosed is a process for making a DMOS, including lining a groove with a dielectric material to form an inner groove having sidewalls extending through the bottom of the first groove, and lining the inner groove with a dielectric material to obtain increased thickness of the gate dielectric on the sidewalls of the inner groove.
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Citations
9 Claims
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1. A method of making a semiconductor device comprising the steps of:
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providing a first region of semiconductor material having a first conductivity type; forming a second region of semiconductor material having a second conductivity type, overlying said first region; forming a first groove, said first groove extending through said second and third regions and into said first region so that a first portion of said third region and a first portion of said second region lie on at least one side of said first groove; lining said first groove with a dielectric material thereby forming a second, inner groove, having a first portion of said dielectric material of a predetermined thickness on a sidewall of said first groove thicker than a second portion thereof of a predetermined thickness on said sidewall of said first groove, with the first portion thereof closer to the depth of the first groove than the second portion thereof; filling the depth of said second, inner groove with a conductive material; and forming an insulating layer over the device resulting from the preceding steps. - View Dependent Claims (2, 3, 5, 6, 7, 8)
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4. The method of claim 10 wherein said step of filling the bottom portion comprises the steps of forming said conductive material in said second, inner groove and on the surface of said third region and then etching said conductive material so that said conductive material on the surface of said third region adjacent to said second, inner groove is removed.
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9. A method of making a semiconductor device comprising the steps of:
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providing a first region of semiconductor material having a first conductivity type; forming a second region of semiconductor material having a second conductivity type, opposite the first conductivity type, overlying said first region; forming a third region of said first conductivity type overlying a portion of said second region; forming a first groove having sidewalls and a bottom, said first groove extending through said second and third regions so that a first portion of said third region and a first portion of said second region lie n at least one side of said first groove; lining said first groove with a dielectric material having a uniform thickness on said sidewalls of said first groove; forming a second groove having a sidewalls extending through the bottom of said first groove, said second groove extending into said first region; lining said second groove with a dielectric material having a uniform thickness on the sidewalls of said second groove; whereby said dielectric material on said sidewalls of said second groove is thicker than said dielectric material on said sidewalls of said first groove; filling said first and second grooves with a conductive material; and forming an insulating layer over the device resulting from the preceding steps; and wherein at each step the structure with the exception of the first and second grooves has a flat surface for carrying out of the succeeding step.
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Specification