Semiconductor device with non-uniform trench oxide layer
First Claim
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1. A semiconductor device, comprising:
- a substrate layer;
an epitaxial layer adjacent to the substrate layer;
a first trench structure formed in the epitaxial layer and having a bottom and sidewalls, wherein the first trench structure further comprises filler material in contact with a source electrode; and
an oxide layer that lines the sidewalls, the oxide layer having a non-uniform thickness along the sidewalls, wherein the thickness of the oxide layer at a first distance from the bottom is less than the thickness of the oxide layer at the bottom, and wherein the thickness of the oxide layer at a second distance from the bottom, greater than the first distance, is less than the thickness of the oxide layer at the first distance;
wherein the epitaxial layer has a non-uniform dopant concentration, wherein the non-uniform dopant concentration varies according to the thickness of the oxide layer adjacent thereto.
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Abstract
A semiconductor device includes a trench formed in an epitaxial layer and an oxide layer that lines the sidewalls of the trench. The thickness of the oxide layer is non-uniform, so that the thickness of the oxide layer toward the top of the trench is thinner than it is toward the bottom of the trench. The epitaxial layer can have a non-uniform dopant concentration, where the dopant concentration varies according to the thickness of the oxide layer.
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Citations
13 Claims
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1. A semiconductor device, comprising:
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a substrate layer; an epitaxial layer adjacent to the substrate layer; a first trench structure formed in the epitaxial layer and having a bottom and sidewalls, wherein the first trench structure further comprises filler material in contact with a source electrode; and an oxide layer that lines the sidewalls, the oxide layer having a non-uniform thickness along the sidewalls, wherein the thickness of the oxide layer at a first distance from the bottom is less than the thickness of the oxide layer at the bottom, and wherein the thickness of the oxide layer at a second distance from the bottom, greater than the first distance, is less than the thickness of the oxide layer at the first distance; wherein the epitaxial layer has a non-uniform dopant concentration, wherein the non-uniform dopant concentration varies according to the thickness of the oxide layer adjacent thereto. - View Dependent Claims (2, 3, 4, 5)
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6. A semiconductor device, comprising:
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a substrate layer; an epitaxial layer adjacent to the substrate layer; a first trench structure formed in the epitaxial layer, the first trench structure having a bottom, a first sidewall, and a second sidewall, wherein the first trench structure further comprises filler material in contact with a source electrode; and an oxide layer that lines the bottom and the first and second sidewalls, the oxide layer comprising a first portion that spans the bottom of the first trench structure from the first sidewall to the second sidewall, a second portion extending from the first portion along the first sidewall, and a third portion extending from the second portion along the first sidewall, wherein the oxide layer has a first thickness in the second portion and a second thickness in the third portion, the second thickness less than the first thickness; wherein the epitaxial layer comprises a first region neighboring the first portion of the oxide layer, a second region neighboring the second portion of the oxide layer, and a third region neighboring the third portion of the oxide layer, wherein the first region has a first dopant concentration, the second region has a second dopant concentration, and the third region has a third dopant concentration, and wherein the third dopant concentration is greater than the second dopant concentration, and the second dopant concentration is greater than the first dopant concentration. - View Dependent Claims (7, 8, 9)
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10. A semiconductor device, comprising:
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a substrate layer; an epitaxial layer adjacent to the substrate layer; a first trench structure formed in the epitaxial layer and having a bottom and sidewalls, wherein the first trench structure further comprises filler material in contact with a source electrode; and an oxide layer that lines the sidewalls, the oxide layer having a non-uniform thickness along the sidewalls, wherein the thickness of the oxide layer at a first distance from the bottom is less than the thickness of the oxide layer at the bottom, and wherein the thickness of the oxide layer at a second distance from the bottom, greater than the first distance, is less than the thickness of the oxide layer at the first distance wherein a region of the epitaxial layer at a depth corresponding to the first distance has a first dopant concentration, and a region of the epitaxial layer at a depth corresponding to the second distance has a second dopant concentration, and wherein the first dopant concentration is less than the second dopant concentration. - View Dependent Claims (11, 12, 13)
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Specification