# US 7,745,338 B2 · Method of forming fine pitch hardmask patterns and method of forming fine patterns of semiconductor device using the same

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- Number: US 7,745,338 B2
- Document ID: US7745338B2
- Status: Granted
- Kind: B2
- Application number: 11/738,155
- Filed: 2007-04-20
- Published: 2008-01-17
- Granted: 2010-06-29
- Earliest claimed: 2006-07-11
- Assignees: Samsung Electronics Co., Ltd.
- Inventors: Ji-hoon Cha; Chang-ki Hong; Kun-tack Lee; Woo-gwan Shim; Chang-sup Mun; Ho-wook Choi
- Web page: https://patentgrep.com/patent/US7745338B2

## CPC

- H10P 50/695: {characterised by the process involved to create the mask, e.g. lift-off masks or sidewalls or to modify the mask}
- H10P 50/696: {Process specially adapted to improve the resolution of the mask}
- H10P 50/71: {using masks for conductive or resistive materials}
- 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 fine pitch hardmask patterns includes forming a hardmask layer on a substrate and forming a plurality of first mask patterns on the hardmask layer. A buffer layer is formed on the plurality of first mask patterns, and has an upper surface defining recesses between adjacent first mask patterns. Second mask patterns are formed within the recesses formed in the upper surface of the buffer layer. The buffer layer is partially removed to expose upper surfaces of the plurality of first mask patterns, and the buffer layer is then partially removed using the first mask patterns and the second mask patterns as an etch mask to expose the hardmask layer between the first mask pattern and the second mask pattern. Using the first mask patterns and the second mask patterns as an etch mask, the hardmask layer is etched to form hardmask patterns.

## Claims

### Claim 1

A method of forming hardmask patterns, comprising:
forming a hardmask layer on a substrate;
forming a plurality of first mask patterns on the hardmask layer;
forming a buffer layer on the plurality of first mask patterns an upper surface of the buffer layer defining recesses between adjacent first mask patterns;
forming second mask patterns within the recesses formed in the upper surface of the buffer layer;
partially removing the buffer layer to expose upper surfaces of the plurality of first mask patterns;
partially removing the buffer layer using the plurality of first mask patterns and the second mask patterns as an etch mask to expose the hardmask layer between the first mask pattern and the second mask pattern; and
etching the hardmask layer using the plurality of first mask patterns and the second mask patterns as an etch mask to form hardmask patterns.

### Claim 2 (depends on 1)

The method of claim 1, wherein the hardmask layer is composed of a material selected from the group consisting of oxide, nitride and a combination of these materials.

### Claim 3 (depends on 2)

The method of claim 2, wherein the first mask patterns and the second mask patterns are each composed of polysilicon.

### Claim 4 (depends on 1)

The method of claim 1, wherein the upper surface of the hardmask layer is an oxide film, and the buffer layer is an oxide film.

### Claim 5 (depends on 1)

The method of claim 1, further comprising, after forming the plurality of first mask patterns and before forming the buffer layer, removing the hardmask layer exposed between the plurality of first mask patterns from the upper surface of the hardmask layer to a depth equal to a first thickness to form low surface portions of the hardmask layer,
wherein the buffer layer covers the plurality of first mask patterns and the low surface portions to the first thickness.

### Claim 6 (depends on 1)

The method of claim 1 wherein the portions of the buffer layer are wet etched.

### Claim 7 (depends on 6)

The method of claim 6, wherein the buffer layer is an oxide film, and an etchant including fluoride (F) is used for removing the portions of the buffer layer.

### Claim 8 (depends on 7)

The method of claim 7, wherein the etchant is diluted hydrogen fluoride (DHF), ammonium fluoride (NH4F) or a combination of these materials.

### Claim 9 (depends on 1)

The method of claim 1, wherein the portions of the buffer layer are dry etched.

### Claim 10 (depends on 9)

The method of claim 9, wherein the buffer layer is an oxide film, and an etchant including fluoride is used for dry etching the portions of the buffer layer.

### Claim 11 (depends on 10)

The method of claim 10, wherein the etchant is mixed gas formed of a fluorocarbon having the formula of CxFy (where x and y are each an integer from one to ten), oxygen (O2) and argon (Ar).

### Claim 12

A method of forming hardmask patterns, comprising:
forming a hardmask layer on a substrate;
forming a plurality of first mask patterns on the hardmask layer at a first pitch;
forming a buffer layer covering the plurality of first mask patterns, and having an upper surface having recesses between adjacent first mask patterns;
forming second mask patterns filling in the recesses formed in the upper surface of the buffer layer,
partially removing the buffer layer to simultaneously expose upper surfaces of the plurality of first mask patterns and the upper surfaces of the second mask patterns;
partially removing the buffer layer using the plurality of first mask patterns and the second mask patterns as an etch mask to expose the upper surface of the hardmask layer between the first mask pattern and the second mask pattern; and
etching the hardmask layer using the first mask patterns and the second mask patterns as an etch mask to form a plurality of hardmask patterns at a second pitch which is about ½ of the first pitch.

### Claim 13 (depends on 12)

The method of claim 12, wherein the hard mask layer is an oxide film, a nitride film or a combination of these films.

### Claim 14 (depends on 12)

The method of claim 12, wherein the first mask pattern and the second mask pattern are each composed of polysilicon.

### Claim 15 (depends on 12)

The method of claim 12, wherein the second mask patterns are repeatedly formed at a pitch equal to the first pitch.

### Claim 16 (depends on 12)

The method of claim 12, wherein the upper surface of the hardmask layer is an oxide film, and the buffer layer is an oxide film.

### Claim 17 (depends on 12)

The method of claim 12, further comprising, after forming the plurality of first mask patterns and before forming the buffer layer, removing the hardmask layer exposed between the plurality of first mask patterns from the upper surface of the hardmask layer to a depth equal to a first thickness to form low surface portions of the hardmask layer,
wherein the buffer layer covers the plurality of first mask patterns and the low surface portions to the first thickness.

### Claim 18 (depends on 12)

The method of claim 12, wherein the first mask patterns and the second mask patterns are each formed to have a width which is ¼ of the first pitch.

### Claim 19 (depends on 12)

The method of claim 12, wherein the portions of the buffer layer are wet etched.

### Claim 20 (depends on 19)

The method of claim 19, wherein the buffer layer is an oxide film, and an etchant including fluoride (F) is used for removing the portions of the buffer layer.

### Claim 21 (depends on 20)

The method of claim 20, wherein the etchant is diluted hydrogen fluoride (DHF), ammonium fluoride (NH4F) or a combination of these materials.

### Claim 22 (depends on 12)

The method of claim 12, wherein the portions of the buffer layer are dry etched.

### Claim 23 (depends on 22)

The method of claim 22, wherein the buffer layer is an oxide film, and an etchant including fluoride is used for dry etching the portions of the buffer layer.

### Claim 24 (depends on 23)

The method of claim 23, wherein the etchant is a mixed gas of a fluorocarbon having the formula of CxFy (where x and y are each an integer from one to ten), oxygen (O2) and argon (Ar).

### Claim 25

A method of forming fine patterns of a semiconductor device, comprising:
forming a first oxide film on a substrate;
forming a hardmask layer by stacking a nitride film and a second oxide film on the first oxide film;
forming a plurality of first mask patterns on the second oxide film;
forming a third oxide film on the first mask patterns, the third oxide film having an upper surface that defines recesses between adjacent first mask patterns;
forming second mask patterns within the recesses formed in the upper surface of the third oxide film;
partially removing the third oxide film to expose the upper surfaces of the first mask patterns;
partially removing the third oxide film to expose the hardmask layer using the first mask patterns and the second mask patterns as an etch mask;
etching the hardmask layer using the first mask patterns and the second mask patterns as an etch mask to form hardmask patterns;
etching the first oxide film and the substrate using the hardmask patterns as an etch mask to form trenches in the substrate, and
filling the trenches with an insulating film to form an isolation region.

### Claim 26 (depends on 25)

The method of claim 25, wherein the first mask patterns and the second mask patterns are each composed of polysilicon.

### Claim 27 (depends on 25)

The method of claim 25, further comprising: after forming the plurality of first mask patterns and before forming the third oxide film, removing the second oxide film exposed between the plurality of first mask patterns from the upper surface of the hardmask layer to a depth equal to a first thickness to form low surface portions of the second oxide film,
wherein the third oxide film covers the plurality of first mask patterns and the low surface portions to the first thickness.

### Claim 28 (depends on 25)

The method of claim 25, wherein the portions of the third oxide firm are wet etched.

### Claim 29 (depends on 25)

The method of claim 25, wherein the portions of the third oxide firm are dry etched.

### Claim 30

A method of forming fine patterns of a semiconductor device, comprising:
forming a hardmask layer on an etch film subjected to etching on a substrate;
forming a plurality of first mask patterns on the hardmask layer;
forming a buffer layer on the first mask patterns, the buffer layer having an upper surface defining recesses between adjacent first mask patterns;
forming second mask patterns within the recesses formed in the upper surface of the buffer layer;
partially removing the buffer layer to expose upper surfaces of the first mask patterns;
partially removing the buffer layer using the first mask patterns and the second mask patterns as an etch mask to expose the hardmask layer;
etching the hard mask layer using the first mask patterns and the second mask patterns as an etch mask to form hardmask patterns; and
etching the etch film using the hardmask patterns as an etch mask.

### Claim 31 (depends on 30)

The method of claim 30, wherein the buffer layer is an oxide film; and the first mask patterns and the second mask patterns are each composed of polysilicon.

### Claim 32 (depends on 30)

The method of claim 30, further comprising, after forming the plurality of first mask patterns and before forming the buffer layer, removing the hardmask layer exposed between the plurality of first mask patterns from the upper surface of the hardmask layer to a depth equal to a first thickness to form low surface portions of the hardmask layer,
wherein the buffer layer covers the first mask patterns and the low surface portions to the first thickness.

### Claim 33 (depends on 30)

The method of claim 30, wherein the portions of the buffer layer are wet etched.

### Claim 34 (depends on 30)

The method of claim 30, wherein the portions of the buffer layer are dry etched.