Apparatus and method for power MOS transistor
First Claim
1. A method comprising:
- growing a first epitaxial layer over a substrate;
growing a second epitaxial layer over the first epitaxial layer, wherein the first epitaxial layer and the second epitaxial layer have different conductivity types;
forming a first trench extending through the second epitaxial layer and partially through the first epitaxial layer;
depositing a gate dielectric layer on sidewalls and a bottom of the first trench;
depositing a gate electrode layer over the gate dielectric layer;
applying a first etching process to the gate electrode layer, wherein as a result of performing the step of applying the first etching process to the gate electrode layer, a top surface of the first epitaxial layer is higher than a top surface of the gate electrode layer;
forming a source region underneath a center portion of the bottom of the first trench;
applying a second etching process to the gate dielectric layer until the source region is exposed;
forming a second trench by removing a center portion of the source region, wherein the second trench extend through the source region and partially through the first epitaxial layer;
forming a doped region having a first portion in the first epitaxial layer and a second portion in the substrate; and
forming a field plate having a lower portion in the second trench and an upper portion in the first trench.
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Abstract
A method comprises providing a substrate with a second conductivity type, growing a first epitaxial layer having the second conductivity type, growing a second epitaxial layer having a first conductivity type, forming a trench in the first epitaxial layer and the second epitaxial layer, forming a gate electrode in the trench, applying an ion implantation process using first gate electrode as an ion implantation mask to form a drain-drift region, forming a field plate in the trench, forming a drain region in the second epitaxial layer, wherein the drain region has the first conductivity type and forming a source region in the first epitaxial layer, wherein the source region has the first conductivity type, and wherein the source region is electrically coupled to the field plate.
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Citations
20 Claims
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1. A method comprising:
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growing a first epitaxial layer over a substrate; growing a second epitaxial layer over the first epitaxial layer, wherein the first epitaxial layer and the second epitaxial layer have different conductivity types; forming a first trench extending through the second epitaxial layer and partially through the first epitaxial layer; depositing a gate dielectric layer on sidewalls and a bottom of the first trench; depositing a gate electrode layer over the gate dielectric layer; applying a first etching process to the gate electrode layer, wherein as a result of performing the step of applying the first etching process to the gate electrode layer, a top surface of the first epitaxial layer is higher than a top surface of the gate electrode layer; forming a source region underneath a center portion of the bottom of the first trench; applying a second etching process to the gate dielectric layer until the source region is exposed; forming a second trench by removing a center portion of the source region, wherein the second trench extend through the source region and partially through the first epitaxial layer; forming a doped region having a first portion in the first epitaxial layer and a second portion in the substrate; and forming a field plate having a lower portion in the second trench and an upper portion in the first trench. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method comprising:
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growing a p-type epitaxial layer over a p-type substrate; growing an n-type epitaxial layer over the p-type epitaxial layer; forming a first trench in the n-type epitaxial layer and the p-type epitaxial layer, wherein a bottom surface of the first trench is higher than a top surface of the p-type substrate; depositing a gate electrode layer on sidewalls and a bottom of the first trench; forming a source region underneath a center portion of the bottom of the first trench, wherein a bottom surface of the source region is higher than the top surface of the p-type substrate; forming a second trench, wherein the second trench extends through the source region and partially through the p-type epitaxial layer; forming a doped region underneath the source region, wherein the doped region has a first portion in the p-type epitaxial layer and a second portion in the p-type substrate; forming a field plate having a lower portion in the second trench and an upper portion in the first trench; and forming a drain region in the n-type epitaxial layer, wherein a bottom surface of the drain region is higher than a top surface of the field plate. - View Dependent Claims (11, 12, 13, 14)
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15. A method comprising:
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providing a substrate with a second conductivity type; growing a first epitaxial layer having the second conductivity type; growing a second epitaxial layer having a first conductivity type; forming a trench in the first epitaxial layer and the second epitaxial layer; forming a gate electrode in the trench; applying an ion implantation process to form a drain-drift region; forming a field plate in the trench; forming a drain region in the second epitaxial layer, wherein the drain region has the first conductivity type; and forming a source region in the first epitaxial layer, wherein the source region has the first conductivity type, and wherein the source region is electrically coupled to the field plate. - View Dependent Claims (16, 17, 18, 19, 20)
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Specification