SEMICONDUCTOR DEVICE AND FABRICATION METHOD THEREOF
First Claim
1. A semiconductor device, comprising:
- a semiconductor substrate having a gate trench comprised of an upper trench and a lower trench, wherein the upper trench is wider than the lower trench, wherein the upper trench and the lower trench are both located within the semiconductor substrate, and wherein the upper trench has a vertical sidewall;
a gate embedded in the gate trench, wherein the gate comprises an upper portion and a lower portion;
a first gate dielectric layer between the upper portion and the vertical sidewall of the upper trench, wherein the first gate dielectric layer has a first thickness; and
a second gate dielectric layer between the lower portion and a sidewall of the lower trench, wherein the second gate dielectric layer has a second thickness that is smaller than the first thickness.
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Accused Products
Abstract
A semiconductor device includes a semiconductor substrate having a gate trench including an upper trench and a lower trench. The upper trench is wider than the lower trench. A gate is embedded in the gate trench. The gate includes an upper portion and a lower portion. A first gate dielectric layer is between the upper portion and a sidewall of the upper trench. The first gate dielectric layer has a first thickness. A second gate dielectric layer is between the lower portion and a sidewall of the lower trench and between the lower portion and a bottom surface of the lower trench. The second gate dielectric layer has a second thickness that is smaller than the first thickness.
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Citations
20 Claims
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1. A semiconductor device, comprising:
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a semiconductor substrate having a gate trench comprised of an upper trench and a lower trench, wherein the upper trench is wider than the lower trench, wherein the upper trench and the lower trench are both located within the semiconductor substrate, and wherein the upper trench has a vertical sidewall; a gate embedded in the gate trench, wherein the gate comprises an upper portion and a lower portion; a first gate dielectric layer between the upper portion and the vertical sidewall of the upper trench, wherein the first gate dielectric layer has a first thickness; and a second gate dielectric layer between the lower portion and a sidewall of the lower trench, wherein the second gate dielectric layer has a second thickness that is smaller than the first thickness. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method for fabricating a semiconductor device, comprising:
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providing a semiconductor substrate; forming an upper trench in the semiconductor substrate; depositing a first gate dielectric layer on interior surface of the upper trench, wherein the first gate dielectric layer has a first thickness; anisotropically etching the first gate dielectric layer and the semiconductor substrate, thereby forming a lower trench in a self-aligned manner, wherein the upper trench and the lower trench constitute a gate trench; and thermally growing a second gate dielectric layer on interior surface of the lower trench, wherein the second gate dielectric layer has a second thickness, and the second thickness is less than the first thickness. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification