Trench DMOS transistor having reduced punch-through
First Claim
1. A method of forming a trench DMOS transistor cell comprising the steps of:
- providing a substrate of a first conductivity type;
forming a body region on the substrate, said body region having a second conductivity type;
forming a masking layer defining at least one trench;
forming the trench defined by the masking layer, said trench extending through the body region and the substrate;
forming an insulating layer that lines the trench;
forming a conductive electrode in the trench overlying the insulating layer;
forming a source region of the first conductivity type in the body region adjacent to the trench; and
wherein the step of forming the trench includes the steps of etching the trench and smoothing sidewalls of the trench with a sacrificial oxide layer before removal of the masking layer that defines the trench.
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Accused Products
Abstract
A method of forming a trench DMOS transistor is provides which reduces punch-through. The method begins by providing a substrate of a first conductivity type. A body region, which has a second conductivity type, is formed on the substrate. A masking layer is formed which defines at least one trench. Next, the trench and an insulating layer that lines the trench are formed. A conductive electrode is then formed in the trench, which overlies the insulating layer. A source region of the first conductivity type is formed in the body region adjacent to the trench. The step of forming the trench includes the steps of etching the trench and smoothing the sidewalls of the trench with a sacrificial oxide layer before removal of the masking layer that defines the trench.
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Citations
20 Claims
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1. A method of forming a trench DMOS transistor cell comprising the steps of:
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providing a substrate of a first conductivity type;
forming a body region on the substrate, said body region having a second conductivity type;
forming a masking layer defining at least one trench;
forming the trench defined by the masking layer, said trench extending through the body region and the substrate;
forming an insulating layer that lines the trench;
forming a conductive electrode in the trench overlying the insulating layer;
forming a source region of the first conductivity type in the body region adjacent to the trench; and
wherein the step of forming the trench includes the steps of etching the trench and smoothing sidewalls of the trench with a sacrificial oxide layer before removal of the masking layer that defines the trench. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method of forming a trench DMOS transistor cell comprising the steps of:
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providing a substrate of a first conductivity type;
forming a body region on the substrate, said body region having a second conductivity type;
forming a masking layer defining at least one trench;
forming the trench defined by the masking layer, said trench extending through the body region and the substrate;
forming an insulating layer that lines the trench;
forming a polysilicon conductive electrode in the trench overlying the insulating layer;
forming a source region of the first conductivity type in the body region adjacent to the trench; and
wherein the step of forming the polysilicon conductive electrode includes the steps of depositing a layer of undoped polysilicon followed by a layer of doped polysilicon. - View Dependent Claims (11, 12, 13, 14, 15, 16)
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17. A trench DMOS transistor cell, comprising:
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a substrate of a first conductivity type;
a body region on the substrate, said body region having a second conductivity type;
at least one trench extending through the body region and the substrate;
an insulating layer that lines the trench;
a conductive electrode in the trench overlying the insulating layer, said conductive electrode including a doped layer and an undoped layer; and
a source region of the first conductivity type in the body region adjacent to the trench. - View Dependent Claims (18, 19, 20)
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Specification