Trench DMOS transistor having a zener diode for protection from electro-static discharge
First Claim
1. A method of making a trench DMOS transistor having overvoltage protection, said method comprising the steps of comprising:
- providing a substrate of a first conductivity type;
forming a body region by an implantation of a second conductivity type on the substrate;
forming at least one trench extending through the body region, wherein said body region is formed prior to the step of forming at least one trench;
depositing an insulating layer that lines the trench and overlies said body region;
depositing a conductive electrode in the trench overlying the insulating layer;
implanting a dopant of the first conductivity type to form a source region in the body region adjacent to the trench;
depositing an undoped polysilicon layer overlying a portion of the insulating layer; and
implanting a dopant of the first conductivity type to form a plurality of cathode regions in the undoped polysilicon layer, said plurality of cathode regions being separated by at least one anode region.
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Abstract
A trench DMOS transistor having overvoltage protection includes a substrate of a first conductivity type and a body region of a second conductivity type formed over the substrate. At least one trench extends through the body region and the substrate. An insulating layer lines the trench and overlies the body region. A conductive electrode is deposited in the trench so that it overlies the insulating layer. A source region of the first conductivity type is formed in the body region adjacent to the trench. An undoped polysilicon layer overlies a portion of the insulating layer. A plurality of cathode regions of the first conductivity type are formed in the undoped polysilicon layer. At least one anode region is in contact with adjacent ones of the plurality of cathode regions.
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Citations
13 Claims
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1. A method of making a trench DMOS transistor having overvoltage protection, said method comprising the steps of comprising:
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providing a substrate of a first conductivity type;
forming a body region by an implantation of a second conductivity type on the substrate;
forming at least one trench extending through the body region, wherein said body region is formed prior to the step of forming at least one trench;
depositing an insulating layer that lines the trench and overlies said body region;
depositing a conductive electrode in the trench overlying the insulating layer;
implanting a dopant of the first conductivity type to form a source region in the body region adjacent to the trench;
depositing an undoped polysilicon layer overlying a portion of the insulating layer; and
implanting a dopant of the first conductivity type to form a plurality of cathode regions in the undoped polysilicon layer, said plurality of cathode regions being separated by at least one anode region. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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Specification