# US 9,040,371 B2 · Integration of dense and variable pitch fin structures

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- Number: US 9,040,371 B2
- Document ID: US9040371B2
- Status: Granted
- Kind: B2
- Application number: 13/961,336
- Filed: 2013-08-07
- Published: 2015-02-12
- Granted: 2015-05-26
- Earliest claimed: 2013-08-07
- Assignees: International Business Machines Corporation
- Applicants: International Business Machines Corporation
- Inventors: Kangguo Cheng; Matthew E. Colburn; Bruce B. Doris; Ali Khakifirooz
- Web page: https://patentgrep.com/patent/US9040371B2

## 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}
- H10B 12/36: {the transistor being a FinFET}
- H10D 84/834: {comprising FinFETs}
- H10D 86/011: {comprising FinFETs}
- H10P 50/696: {Process specially adapted to improve the resolution of the mask}
- H10B 10/12: {comprising a MOSFET load element}
- H10D 62/117: {Shapes of semiconductor bodies}
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
- H10B: ELECTRONIC MEMORY DEVICES
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES

## Abstract

Semiconductor devices and method for forming the same. Methods for forming fin structures include forming a protective layer over a set of mandrels in a variable fin pitch region; forming first sidewalls around a set of mandrels in a uniform fin pitch region; removing the set of mandrels in the uniform fin pitch region; removing the protective layer; forming second sidewalls around the first sidewalls in the uniform fin pitch region and the mandrels in the variable fin pitch region; removing the first sidewalls and the mandrels; and etching an underlying layer around the second sidewalls.

## Claims

### Claim 1

A method for forming fin structures, comprising:
forming a protective layer over a set of mandrels in a variable fin pitch region;
forming first sidewalls around a set of mandrels in a uniform fin pitch region;
removing the set of mandrels in the uniform fin pitch region;
removing the protective layer;
forming second sidewalls around the first sidewalls in the uniform fin pitch region and the mandrels in the variable fin pitch region;
removing the first sidewalls and the mandrels; and
etching an underlying layer around the second sidewalls.

### Claim 2 (depends on 1)

The method of claim 1, further comprising removing one or more of the first sidewalls in the uniform pitch region before forming the second sidewalls.

### Claim 3 (depends on 1)

The method of claim 1, wherein the underlying layer comprises a hardmask layer.

### Claim 4 (depends on 3)

The method of claim 3, wherein the underlying layer further comprises one or more additional layers to be etched.

### Claim 5 (depends on 1)

The method of claim 1, wherein the second sidewalls are formed from a different material than a material of the first sidewalls.

### Claim 6 (depends on 5)

The method of claim 5, wherein the material of the second sidewalls has etch selectivity with the material of the first sidewalls and the mandrels.

### Claim 7 (depends on 1)

The method of claim 1, wherein the second sidewalls are thinner than the first sidewalls.

### Claim 8 (depends on 1)

The method of claim 1, wherein the second sidewalls in the uniform fin pitch region have a uniform separation between sidewalls and wherein the second sidewalls in the variable fin pitch region have a variable separation between sidewalls.

### Claim 9

A method for forming fin structures, comprising:
lithographically forming a first set of mandrels in a uniform fin pitch region with uniform width and spacing over a hardmask layer to be patterned;
lithographically forming a second set of mandrels in a variable fin pitch region with variable width and spacing over the hardmask layer to be patterned;
forming a protective layer over a set of mandrels in a variable fin pitch region;
forming first sidewalls around a set of mandrels in a uniform fin pitch region;
removing the set of mandrels in the uniform fin pitch region;
removing the protective layer;
forming second sidewalls around the first sidewalls in the uniform fin pitch region and the mandrels in the variable fin pitch region;
removing the first sidewalls and the mandrels; and
etching an underlying layer around the second sidewalls to form fins, wherein fins in the uniform fin pitch region have a spacing that is less than half of a minimum pitch of a lithography process used to form the mandrels and wherein fins in the variable fin pitch region have a spacing that is greater than half, but less than the minimum pitch of the lithography process.

### Claim 10 (depends on 9)

The method of claim 9, further comprising removing one or more of the first sidewalls in the uniform pitch region before forming the second sidewalls.

### Claim 11 (depends on 9)

The method of claim 9, wherein the underlying layer comprises a hardmask layer.

### Claim 12 (depends on 11)

The method of claim 11, wherein the underlying layer further comprises one or more additional layers to be etched.

### Claim 13 (depends on 9)

The method of claim 9, wherein the second sidewalls are formed from a different material than a material of the first sidewalls.

### Claim 14 (depends on 13)

The method of claim 13, wherein the material of the second sidewalls has etch selectivity with the material of the first sidewalls and the mandrels.

### Claim 15 (depends on 9)

The method of claim 9, wherein the second sidewalls are thinner than the first sidewalls.

### Claim 16 (depends on 9)

The method of claim 9, wherein the second sidewalls in the uniform fin pitch region have a uniform separation between sidewalls and wherein the second sidewalls in the variable fin pitch region have a variable separation between sidewalls.