# US 7,745,885 B2 · High voltage power MOSFET having low on-resistance

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- Number: US 7,745,885 B2
- Document ID: US7745885B2
- Status: Granted
- Kind: B2
- Application number: 11/475,640
- Filed: 2006-06-27
- Published: 2006-11-09
- Granted: 2010-06-29
- Earliest claimed: 2000-06-02
- Assignees: General Semiconductor, Inc.
- Inventors: Richard A. Blanchard
- Web page: https://patentgrep.com/patent/US7745885B2

## CPC

- H10D 30/66: Vertical DMOS [VDMOS] FETs
- H10D 30/0291: {of vertical DMOS [VDMOS] FETs}
- H10D 62/058: {by using trenches, e.g. implanting into sidewalls of trenches or refilling trenches}
- H10D 62/111: {Multiple RESURF structures, e.g. double RESURF or 3D-RESURF structures}
- H10P 74/238: {comprising acting in response to an ongoing measurement without interruption of processing, e.g. endpoint detection or in-situ thickness measurement}
- H10D 62/115: {Dielectric isolations, e.g. air gaps}
- H10D 62/393: {Body regions of DMOS transistors or IGBTs (cell layout of DMOS H10D62/127)}
- H10P 32/141: {the applied layer comprising oxides only}
- H10P 32/1414: {the applied layer being silicon, silicide or SIPOS, e.g. polysilicon or porous silicon}
- H10P 32/171: {being group IV material}
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10

## Abstract

A power MOSFET is provided that includes a substrate of a first conductivity type. An epitaxial layer also of the first conductivity type is deposited on the substrate. First and second body regions are located in the epitaxial layer and define a drift region between them. The body regions have a second conductivity type. First and second source regions of the first conductivity type are respectively located in the first and second body regions. A plurality of trenches are located below the body regions in the drift region of the epitaxial layer. The trenches, which extend toward the substrate from the first and second body regions, are filled with an epitaxially layered material that includes a dopant of the second conductivity type. The dopant is diffused from the trenches into portions of the epitaxial layer adjacent the trenches.

## Claims

### Claim 1

A power MOSFET, comprising:
a substrate of a first conductivity type;
an epitaxial layer on the substrate, said epitaxial layer having a first conductivity type;
first and second body regions located in the epitaxial layer defining a drift region therebetween, said body regions having a second conductivity type;
first and second source regions of the first conductivity type respectively located in the first and second body regions; and
a plurality of trenches located below and extending from said body regions in said drift region of the epitaxial layer, said trenches being filled with an insulating layered material deposited using CVD and having a dopant of the second conductivity type, said trenches extending toward the substrate from the first and second body regions, said dopant being diffused from said trenches into portions of the epitaxial layer adjacent the trenches to covert a portion of said epitaxial layer to the opposite conductivity.

### Claim 2 (depends on 1)

The power MOSFET of claim 1 wherein one of said materials filling the trench is silicon.

### Claim 3 (depends on 1)

The power MOSFET of claim 1 wherein one of said materials filling the trench is a dielectric.

### Claim 4 (depends on 3)

The power MOSFET of claim 3 wherein said dielectric is silicon dioxide.

### Claim 5 (depends on 1)

The power MOSFET of claim 1 wherein said dopant is boron.

### Claim 6 (depends on 2)

The power MOSFET of claim 2 wherein said silicon is at least partially oxidized.

### Claim 7 (depends on 1)

The power MOSFET of claim 1 wherein said material filling the trench includes silicon and a dielectric.

### Claim 8 (depends on 1)

The power MOSFET of claim 1 wherein said body regions include deep body regions.

### Claim 9 (depends on 1)

The power MOSFET of claim 1 wherein said portions of the epitaxial layer adjacent the trenches have a substantially uniform dopant concentration in a direction lateral to the trenches.