# US 10,483,360 B2 · Semiconductor device comprising a gradually increasing field dielectric layer and method of manufacturing a semiconductor device

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- Number: US 10,483,360 B2
- Document ID: US10483360B2
- Status: Granted
- Kind: B2
- Application number: 15/833,576
- Filed: 2017-12-06
- Published: 2018-04-05
- Granted: 2019-11-19
- Earliest claimed: 2015-07-29
- Assignees: Infineon Technologies AG
- Applicants: Infineon Technologies AG
- Inventors: Andreas Meiser; Oliver Haeberlen
- Web page: https://patentgrep.com/patent/US10483360B2

## CPC

- H10D 64/118: {Electrodes comprising insulating layers having particular dielectric or electrostatic properties, e.g. having static charges}
- H10D 30/0287: {using recessing of the source electrodes}
- H10D 30/0289: {using recessing of the gate electrodes, e.g. to form trench gate electrodes}
- H10D 30/658: {having trench gate electrodes}
- H10D 62/127: {of cellular field-effect devices, e.g. multicellular DMOS transistors or IGBTs}
- H10D 64/01: Manufacture or treatment
- H10D 64/112: {comprising multiple field plate segments}
- H10D 64/117: {Recessed field plates, e.g. trench field plates or buried field plates}
- H10D 64/256: {for lateral devices wherein the source or drain electrodes are recessed in semiconductor bodies (source or drain electrodes of TFTs H10D30/673)}
- H10P 30/40: into insulating materials
- H10D 62/154: {Dispositions}
- H10D 62/371: {Inactive supplementary semiconductor regions, e.g. for preventing punch-through, improving capacity effect or leakage current}
- H10D 62/393: {Body regions of DMOS transistors or IGBTs (cell layout of DMOS H10D62/127)}
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10

## Abstract

A method of manufacturing a semiconductor device is providing, which includes forming a trench in a semiconductor substrate, forming an oxide layer over sidewalls and over a bottom side of the trench, performing an ion implantation process, forming a cover layer, and patterning the covering layer, thereby forming an uncovered area and a covered area of the oxide layer, respectively. The method further includes performing an isotropic etching process thereby removing portions of the uncovered area of the oxide layer and removing a part of a surface portion of the covered area adjacent to the uncovered portions, and removing remaining portions of the covering layer.

## Claims

### Claim 1

A method of manufacturing a semiconductor device, the method comprising:
forming a trench in a semiconductor substrate;
forming an oxide layer over sidewalls and over a bottom side of the trench;
performing an ion implantation process so as to damage the oxide layer disposed over the sidewalls and the bottom side of the trench;
forming a covering layer in the trench over the damaged oxide layer;
patterning the covering layer in the trench, thereby forming an uncovered area of the damaged oxide layer at a first area in the trench and a covered area of the damaged oxide layer at a second area in the trench, wherein the covered area of the damaged oxide layer is covered by a remaining portion of the covering layer;
performing an isotropic etching process thereby removing the uncovered area of the damaged oxide layer in the trench and removing a portion of the covered area of the damaged oxide layer in the trench located adjacent to the uncovered area of the damaged oxide layer, wherein the removed portion of the covered area of the damaged oxide layer is located underneath the remaining portion of the covering layer; and
removing the remaining portion of the covering layer.

### Claim 2 (depends on 1)

The method according to claim 1, wherein a tapered oxide layer is formed at a portion of the covered area adjacent to the uncovered area.

### Claim 3 (depends on 1)

The method according to claim 1, wherein the covering layer is patterned to form an opening in the covering layer.

### Claim 4 (depends on 1)

The method according to claim 1, further comprising:
subsequent to removing the remaining portion of the covering layer, filling a fill material into the trench.

### Claim 5 (depends on 4)

The method according to claim 4, further comprising forming the oxide layer over sidewalls and the bottom side of the trench before filling the fill material into the trench.

### Claim 6 (depends on 5)

The method according to claim 5, further comprising:
forming a source region;
forming a drain region;
forming a body region; and
forming a gate electrode, to form components of a field effect transistor,
wherein the fill material in the trench forms a field plate of the field effect transistor.

### Claim 7 (depends on 4)

The method according to claim 4, wherein the fill material is conductive.

### Claim 8 (depends on 1)

The method according to claim 1, wherein the ion implantation process is performed as a tilted ion implantation process so as to implant the sidewalls of the trench.

### Claim 9 (depends on 1)

The method according to claim 1, wherein the first area of the trench includes a first portion of the bottom side of the trench and the second area of the trench includes a second portion of the bottom side of the trench.

### Claim 10 (depends on 9)

The method according to claim 9, wherein:
the first area of the trench includes a first sidewall of the sidewalls, and the second area of the trench includes a second sidewall of the sidewall, the first sidewall and the second sidewall being lateral separated from each other in a first direction, and
a thickness of the removed portion of the covered area of the damaged oxide layer decreases along the first direction extending from the first sidewall to the second sidewall.

### Claim 11 (depends on 10)

The method according to claim 10, wherein a thickness of a remaining portion of the covered area of the oxide layer increases along the first direction that extends from the first sidewall to the second sidewall.

### Claim 12 (depends on 1)

The method according to claim 1, wherein:
the first area of the trench includes a first sidewall of the sidewalls, and the second area of the trench includes a second sidewall of the sidewall, the first sidewall and the second sidewall being lateral separated from each other in a first direction, and
a thickness of the removed portion of the covered area of the damaged oxide layer decreases along the first direction extending from the first sidewall to the second sidewall.

### Claim 13 (depends on 12)

The method according to claim 12, wherein a thickness of a remaining portion of the covered area of the oxide layer increases along the first direction that extends from the first sidewall to the second sidewall.

### Claim 14 (depends on 4)

The method according to claim 4, wherein:
the first area of the trench includes a first sidewall of the sidewalls, and the second area of the trench includes a second sidewall of the sidewall, the first sidewall and the second sidewall being lateral separated from each other in a first direction, and
a thickness of the fill material in the trench decreases along the first direction that extends from the first sidewall to the second sidewall.

### Claim 15 (depends on 1)

The method according to claim 1, wherein:
the first area of the trench includes a first sidewall of the sidewalls, and the second area of the trench includes a second sidewall of the sidewall, the first sidewall and the second sidewall being lateral separated from each other in a first direction, and
subsequent to performing the isotropic etching, a thickness of the oxide layer at the bottom side of the trench gradually increases along the first direction that extends from the first sidewall to the second sidewall.

### Claim 16 (depends on 1)

The method according to claim 1, wherein removing the remaining portion of the covering layer is performed subsequent to performing the isotropic etching process.