# US 2021/0242020 A1 · Multiple Patterning Processes

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- Number: US 2021/0242020 A1
- Document ID: US20210242020A1
- Status: Published application
- Kind: A1
- Application number: 16/780,248
- Filed: 2020-02-03
- Published: 2021-08-05
- Earliest claimed: 2020-02-03
- Assignees: Tokyo Electron Limited
- Applicants: Tokyo Electron Limited
- Inventors: David L. O'Meara; Eric Chih-Fang Liu; Jodi Grzeskowiak; Anton deVilliers; Akiteru Ko; Anthony Dip
- Web page: https://patentgrep.com/patent/US20210242020A1

## CPC

- H10P 76/4085: {characterised by the processes involved to create the masks}
- H10P 76/4088: {Processes for improving the resolution of the masks}
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10

## Abstract

A method of forming a device includes depositing a first etch mask layer over a mandrel formed using a lithography process. The method includes depositing a second etch mask layer over the first etch mask layer. The method includes, using a first anisotropic etching process, etching the first etch mask layer and the second etch mask layer to form an etch mask including the first etch mask layer and the second etch mask layer. The method includes removing the mandrel to expose an underlying surface of the layer to be patterned. The method includes, using the etch mask, forming a feature by performing a second anisotropic etching process to pattern the layer to be patterned, where during the first anisotropic etching process, the first etch mask layer etches at a first rate and the second etch mask layer etches at a second rate, and where the first rate is different from the second rate.

## Claims

### Claim 1

A method of forming a device, the method comprising:
forming a mandrel layer over a layer to be patterned;
patterning the mandrel layer to form a mandrel using a lithography process;
depositing a first etch mask layer over the mandrel;
depositing a second etch mask layer over the first etch mask layer;
using a first anisotropic etching process, etching the first etch mask layer and the second etch mask layer to form an etch mask comprising the first etch mask layer and the second etch mask layer;
removing the mandrel to expose an underlying surface of the layer to be patterned; and
using the etch mask, forming a feature by performing a second anisotropic etching process to pattern the layer to be patterned, wherein during the first anisotropic etching process, the first etch mask layer etches at a first rate and the second etch mask layer etches at a second rate, and wherein the first rate is different from the second rate.

### Claim 2 (depends on 1)

The method of claim 1, wherein the first etch mask layer and the second etch mask layer are deposited using a conformal deposition process.

### Claim 3 (depends on 1)

The method of claim 1, wherein the first rate is at least two times the second rate.

### Claim 4 (depends on 1)

The method of claim 1, wherein the first etch mask layer comprises silicon oxide and the second etch mask layer comprises silicon nitride or titanium oxide.

### Claim 5 (depends on 1)

The method of claim 1, wherein the first etch mask layer comprises silicon and the second etch mask layer comprises a metal.

### Claim 6 (depends on 1)

The method of claim 1, wherein the first anisotropic etching process is configured to change with the composition of the first etch mask layer and the composition of the second etch mask layer to form the etch mask having a predefined shape.

### Claim 7 (depends on 1)

The method of claim 1, further comprising:
depositing a third etch mask layer before depositing the first etch mask layer; and
wherein the first anisotropic etching process comprises etching the third etch mask layer, wherein the etch mask comprises the first etch mask layer, the second etch mask layer, and the third etch mask layer, wherein during the first anisotropic etching process, the third etch mask layer etches at a third rate, and wherein the third rate is different from the second rate.

### Claim 8 (depends on 7)

The method of claim 7, wherein the third rate is at least two times the first rate and the first rate is at least two times the second rate.

### Claim 9 (depends on 7)

The method of claim 7, wherein the first layer and the third layer comprise the same material.

### Claim 10

A method of forming a device, the method comprising:
forming a mandrel over a layer to be patterned;
depositing a first etch mask layer over the mandrel;
using a first anisotropic etching process, etching the first etch mask layer to form a spacer on the mandrel;
depositing a second etch mask layer over the first etch mask layer and the mandrel;
using a second anisotropic etching process, etching the second etch mask layer to form a liner over the spacer;
removing the mandrel to expose an underlying surface of the layer to be patterned;
using a third anisotropic etching process, etching the spacer and the liner to form an etch mask comprising the first etch mask layer and the second etch mask layer; and
using the etch mask, forming a feature by performing a fourth anisotropic etching process to pattern the layer to be patterned, wherein during the third anisotropic etching process, the first etch mask layer etches at a first rate and the second etch mask layer etches at a second rate, and wherein the first rate is different from the second rate.

### Claim 11 (depends on 10)

The method of claim 10, wherein the first etch mask layer and the second etch mask layer are deposited using a conformal deposition process.

### Claim 12 (depends on 10)

The method of claim 10, wherein the second rate is at least two times the first rate.

### Claim 13 (depends on 10)

The method of claim 10, wherein the first etch mask layer comprises silicon oxide and the second etch mask layer comprises silicon nitride.

### Claim 14 (depends on 10)

The method of claim 10, wherein the first etch mask layer comprises silicon oxide and the second etch mask layer comprises titanium oxide.

### Claim 15 (depends on 10)

The method of claim 10, wherein the first layer comprises silicon and the second layer comprises a metal.

### Claim 16 (depends on 10)

The method of claim 10, wherein the third anisotropic etching process is configured to change with the composition of the spacer and the composition of the liner to form the etch mask having a predefined shape.

### Claim 17

A method of forming a device, the method comprising:
forming a mandrel over a layer to be patterned;
forming a spacer along sidewalls of the mandrel, wherein the spacer comprises a first sidewall comprising a first material and a second sidewall comprising a second material different from the first material, wherein the first sidewall and the second sidewall are vertical and parallel to each other;
removing the mandrel after forming the spacer; and
using the spacer as an etch mask, forming a feature in the layer to be patterned using an anisotropic etching process.

### Claim 18 (depends on 17)

The method of claim 17, wherein the first sidewall and the second sidewall comprise no foot.

### Claim 19 (depends on 17)

The method of claim 17, wherein the first sidewall and the second sidewall comprise only a planar surface with no curved surface.

### Claim 20 (depends on 17)

The method of claim 17, wherein forming the mandrel comprises using electron beam lithography or extreme ultraviolet lithography.