# US 6,720,114 B1 · Method of forming an alternating phase shift circuitry fabrication mask, method of forming a circuitry fabrication mask having a subtractive alternating phase shift region, and alternating phase shift mask

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- Number: US 6,720,114 B1
- Document ID: US6720114B1
- Status: Granted
- Kind: B1
- Application number: 09/643,005
- Filed: 2000-08-21
- Granted: 2004-04-13
- Earliest claimed: 2000-08-21
- Assignees: Micron Technology, Inc.
- Inventors: Amy A. Winder; Paul Chipman
- Web page: https://patentgrep.com/patent/US6720114B1

## CPC

- G03F 1/30: Alternating PSM, e.g. Levenson-Shibuya PSM; Preparation thereof
- G03F: PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR; (phototypographic composing devices B41B; photosensitive materials or processes for photographic purposes G03C; electrophotography, sensitive layers or processes therefor G03G)

## Abstract

Disclosed are methods of forming alternating phase shift circuitry fabrication masks, methods of forming circuitry fabrication masks having a subtractive alternating phase shift region, and alternating phase shift masks. In one implementation, a method of forming an alternating phase shift circuitry fabrication mask incudes combining circuitry pattern data biasing and wet undercut etching of light transmissive substrate material adjacent phase shift regions of the mask in fabricating the mask. In one implementation, a method of forming an alternating phase shift circuitry fabrication mask includes combining circuitry pattern data biasing and wet undercut etching of light transmissive substrate material adjacent phase shift regions of the mask effective to achieve a first data biased pattern when using the mask to fabricate circuitry of a desired circuit pattern on another substrate. The first data biased pattern has at least some first resolution spacing falling between a discrete finite resolution spacing of which a writing tool used to fabricate the mask is capable of achieving.

## Claims

### Claim 1

A method of forming an alternating phase shift circuitry fabrication mask comprising combining both circuitry pattern data biasing of a masking layer in its formation and then wet undercut etching of light transmissive substrate material adjacent phase shift regions of the mask in fabricating the mask, the data biasing comprising forming at least some openings in the masking layer to be larger than features to be fabricated therewith on a substrate using the mask.

### Claim 2

A method of forming an alternating phase shift circuitry fabrication mask comprising combining both circuitry pattern data biasing of a masking layer in its formation and then wet undercut etching of light transmissive substrate material adjacent phase shift regions of the mask in fabricating the mask, the method being void of any undercut etching of the light transmissive substrate material beneath a masking layer adjacent non-phase shifted regions of the mask.

### Claim 3 (depends on 1)

The method of claim 1 comprising dry etching the light transmissive substrate material to at least partially form the phase shift regions prior to the wet undercut etching.

### Claim 4

A method of forming an alternating phase shift circuitry fabrication mask comprising:
providing a mask writing tool capable of producing at least first and second discrete finite resolution spacings but incapable of producing a discrete finite resolution spacing between the first and second resolution spacings; and
using said writing tool and combining both circuitry pattern data biasing of a masking layer in its formation and then wet undercut etching of light transmissive substrate material adjacent phase shift regions of the mask effective to achieve a first data biased pattern when using the mask to fabricate circuitry of a desired circuit pattern on another substrate, the first data biased pattern having at least some resolution spacing falling within said first and second resolution spacings of which the writing tool is incapable of producing.

### Claim 5 (depends on 4)

The method of claim 4 being void of any undercut etching of the light transmissive substrate material adjacent non-phase shifted regions of the mask.

### Claim 6 (depends on 4)

The method of claim 4 comprising dry etching the light transmissive substrate material to at least partially form the phase shift regions prior to the wet undercut etching.

### Claim 7

A method of forming a circuitry fabrication mask having a subtractive alternating phase shift region, comprising:
providing a light shielding layer over a light transmissive substrate;
determining a desired circuit pattern to be fabricated on another substrate using the mask, the desired circuit pattern comprising two adjacent features;
forming first and second adjacent openings into the light shielding layer configured to form the respective two adjacent features, one of the first and second adjacent openings being data biased to be larger than the feature to be fabricated therewith on the another substrate;
masking the other of the first and second adjacent openings while leaving the one of the first and second openings outwardly exposed;
while the other opening is masked and the one of the first and second openings is outwardly exposed, dry etching the light transmissive substrate to at least partially form a phase shift region through the one opening as compared to the masked adjacent other opening; and
while the other opening is masked and the one of the first and second openings is outwardly exposed, wet etching the light transmissive substrate relative to the light shielding layer through the one opening effective to undercut at least some of the light shielding layer proximate the one opening.

### Claim 8 (depends on 7)

The method of claim 7 wherein the other of the first and second adjacent openings is not data biased to be different in size than the feature to be fabricated therewith on the another substrate.

### Claim 9 (depends on 7)

The method of claim 7 wherein the other of the first and second adjacent openings is data biased to be different in size than the feature to be fabricated therewith on the another substrate.

### Claim 10 (depends on 9)

The method of claim 9 wherein the other of the first and second adjacent openings is data biased to be smaller in size than the feature to be fabricated therewith on the another substrate.

### Claim 11 (depends on 9)

The method of claim 9 wherein the other of the first and second adjacent openings is data biased to be larger in size than the feature to be fabricated therewith on the another substrate.

### Claim 12 (depends on 7)

The method of claim 7 wherein the light shielding layer comprises metal.

### Claim 13 (depends on 7)

The method of claim 7 wherein the light transmissive substrate comprises quartz.

### Claim 14 (depends on 7)

The method of claim 7 wherein the dry etching is conducted prior to the wet etching.

### Claim 15 (depends on 7)

The method of claim 7 wherein the wet etching is conducted prior to the dry etching.

### Claim 16 (depends on 7)

The method of claim 7 comprising unmasking the other opening intermediate the wet and dry etching and checking the phase intermediate the wet and dry etching.

### Claim 17 (depends on 7)

The method of claim 7 wherein a masking material is utilized in the masking, the same masking material remaining on the substrate during both the dry etching and the wet etching.

### Claim 18 (depends on 7)

The method of claim 7 wherein the wet etching substantially uniformly undercuts the light shielding layer.

### Claim 19

A method of forming a circuitry fabrication mask having a subtractive alternating phase shift region, comprising:
providing a light shielding layer over a light transmissive substrate;
determining a desired circuit pattern to be fabricated on another substrate using the mask;
data biasing the circuit pattern to derive a data biased pattern having at least some first alternating features of the circuitry to have first mask openings which are larger than the respective features to be fabricated on the another substrate, and having at least some second alternating features of the circuitry to have second mask openings, the first mask openings alternating with the second mask openings;
forming the data biased pattern into the light shielding layer including forming the alternating first mask openings and the alternating second mask openings into the light shielding layer;
masking the second mask openings in the light shielding layer while leaving the first mask openings in the light shielding layer exposed;
while the second mask openings are masked and the first mask openings in the light shielding layer are exposed, dry etching the light transmissive substrate to at least partially form alternating phase shift regions through the first openings as compared to the masked alternating second openings; and
while the second mask openings are masked and the first mask openings in the light shielding layer are exposed, wet etching the light transmissive substrate relative to the light shielding layer through the first openings effective to undercut at least some of the light shielding layer proximate the first mask openings.

### Claim 20 (depends on 19)

The method of claim 19 wherein the second mask openings are not data biased to be different in size than the respective features to be fabricated therewith on the another substrate.

### Claim 21 (depends on 19)

The method of claim 19 wherein the second mask openings are data biased to be different in size than the respective features to be fabricated therewith on the another substrate.

### Claim 22 (depends on 21)

The method of claim 21 wherein the second mask openings are data biased to be smaller in size than the respective features to be fabricated therewith on the another substrate.

### Claim 23 (depends on 21)

The method of claim 21 wherein the second mask openings are data biased to be larger in size than the respective features to be fabricated therewith on the another substrate.

### Claim 24 (depends on 19)

The method of claim 19 wherein the dry etching is conducted prior to the wet etching.

### Claim 25 (depends on 19)

The method of claim 19 wherein the wet etching is conducted prior to the dry etching.

### Claim 26 (depends on 19)

The method of claim 19 wherein a masking material is utilized in the masking, the same masking material remaining on the substrate during both the dry etching and the wet etching.

### Claim 27 (depends on 19)

The method of claim 19 comprising unmasking the second mask openings intermediate the wet and dry etching and checking the phase intermediate the wet and dry etching.

### Claim 28

A method of forming a circuitry fabrication mask having a subtractive alternating phase shift region, comprising:
providing a light shielding layer over a light transmissive substrate;
determining a desired circuit pattern to be fabricated on another substrate using the mask;
providing a mask writing tool capable of producing at least first and second discrete finite resolution spacings but incapable of producing a discrete finite resolution spacing between the first and second resolution spacings;
data biasing the circuit pattern to derive a first data biased pattern having at least some first resolution spacing between the first and second resolution spacings;
deriving a second data biased pattern from the first data biased pattern to change the first resolution spacing to a second resolution spacing equaling one of the first and second discrete finite resolution spacings of which the writing tool is capable;
forming the second biased pattern into the light shielding layer, the second data bias pattern having at least some first alternating features having first mask openings which are larger than the respective circuitry features to be fabricated on the another substrate, and having at least some second alternating features of the circuitry to have second mask openings, the first mask openings alternating with the second mask openings;
masking the second mask openings in the light shielding layer while leaving the first mask openings in the light shielding layer exposed;
while the second mask openings are masked and the first mask openings in the light shielding layer are exposed, dry etching the light transmissive substrate to at least partially form alternating phase shift regions through the first openings as compared to the masked alternating second openings; and
while the second mask openings are masked and the first mask openings in the light shielding layer are exposed, wet etching the light transmissive substrate through the first openings effective to undercut at least some of the light shielding layer proximate the first mask openings to a degree effective to achieve the first data biased pattern when using the mask to fabricate circuitry of the desired circuit pattern on another substrate.

### Claim 29 (depends on 28)

The method of claim 28 wherein the second mask openings are data biased to be smaller in size than the respective features to be fabricated therewith on the another substrate.

### Claim 30 (depends on 28)

The method of claim 28 wherein the second mask openings are data biased to be larger in size than the respective features to be fabricated therewith on the another substrate.

### Claim 31 (depends on 28)

The method of claim 28 wherein the dry etching is conducted prior to the wet etching.

### Claim 32 (depends on 28)

The method of claim 28 wherein the wet etching is conducted prior to the dry etching.

### Claim 33

An alternating phase shift mask comprising:
a light transmissive substrate having an outer surface;
a light shielding layer received over the light transmissive substrate outer surface, the light shielding layer comprising a circuitry pattern at least a portion of which has a first series of openings therethrough which alternate with a second series of openings therethrough, at least the first series of openings being data biased to be larger than respective circuitry features to be fabricated on another substrate using the mask, the first series of openings respectively comprising opposing sidewalls;
subtractive phase shift opening regions in the light transmissive substrate aligned with the first series of openings, the phase shift opening regions respectively having opposing sidewalls which are below and laterally recessed outwardly of the respective sidewalls of the first series of openings in the light shielding layer in at least one cross section, the phase shift opening regions having respective bases; and
the second series of openings defining therethrough a series of respective exposed second light transmissive substrate bases which are substantially coplanar with the light transmissive substrate outer surface upon which the light shielding layer is proximately received.

### Claim 34 (depends on 33)

The alternating phase shift mask of claim 33 wherein the second series of circuit openings are not data biased to be different in size than the respective circuitry features to be fabricated therewith on the another substrate.

### Claim 35 (depends on 33)

The alternating phase shift mask of claim 33 wherein the second series of circuit openings are data biased to be different in size than the respective circuitry features to be fabricated therewith on the another substrate.

### Claim 36 (depends on 35)

The alternating phase shift mask of claim 35 wherein the second series of circuit openings are data biased to be smaller in size than the respective circuitry features to be fabricated therewith on the another substrate.

### Claim 37 (depends on 35)

The alternating phase shift mask of claim 35 wherein the second series of circuit openings are data biased to be larger in size than the respective circuitry features to be fabricated therewith on the another substrate.

### Claim 38 (depends on 35)

The alternating phase shift mask of claim 35 wherein the light shielding layer comprises metal.

### Claim 39 (depends on 35)

The alternating phase shift mask of claim 35 wherein the light transmissive substrate comprises quartz.

### Claim 40 (depends on 1)

The method of claim 1 wherein the data biasing also comprises forming at least some openings in the masking layer to be smaller than features to be fabricated therewith on the substrate using the mask.

### Claim 41 (depends on 1)

The method of claim 1 being void of any undercut etching of the light transmissive substrate material adjacent non-phase shifted regions of the mask.

### Claim 42 (depends on 2)

The method of claim 2 comprising dry etching the light transmissive substrate material to at least partially form the phase shift regions prior to the wet undercut etching.

### Claim 43

A method of forming an alternating phase shift circuitry fabrication mask comprising combining both circuitry pattern data biasing of a masking layer in its formation and then wet undercut etching of light transmissive substrate material adjacent phase shift regions of the mask in fabricating the mask, the data biasing comprising forming at least some adjacent openings in the masking layer to be larger and smaller than features to be fabricated therewith on a substrate using the mask.

### Claim 44 (depends on 43)

The method of claim 43 being void of any undercut etching of the light transmissive substrate material beneath the masking layer adjacent non-phase shifted regions of the mask.

### Claim 45 (depends on 43)

The method of claim 43 comprising dry etching the light transmissive substrate material to at least partially form the phase shift regions prior to the wet undercut etching.