# US 2015/0147686 A1 · Extreme Ultraviolet Lithography Process And Mask

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- Number: US 2015/0147686 A1
- Document ID: US20150147686A1
- Status: Published application
- Kind: A1
- Application number: 14/087,508
- Filed: 2013-11-22
- Published: 2015-05-28
- Earliest claimed: 2013-11-22
- Assignees: Taiwan Semiconductor Manufacturing Company, Ltd.
- Applicants: Taiwan Semiconductor Manufacturing Company, Ltd.
- Inventors: Yen-Cheng Lu; Shinn-Sheng Yu; Jeng-Horng Chen; Anthony Yen
- Web page: https://patentgrep.com/patent/US20150147686A1

## CPC

- G03F 1/24: Reflection masks; Preparation thereof
- G03F 1/48: Protective coatings
- G03F 1/52: Reflectors
- G03F 7/2002: {with visible light or UV light, through an original having an opaque pattern on a transparent support, e.g. film printing, projection printing; by reflection of visible or UV light from an original such as a printed image}
- G03F 7/2022: {Multi-step exposure, e.g. hybrid; backside exposure; blanket exposure, e.g. for image reversal; edge exposure, e.g. for edge bead removal; corrective exposure}
- G03F 7/70466: {Multiple exposures, e.g. combination of fine and coarse exposures, double patterning or multiple exposures for printing a single feature (stitching G03F7/70475)}
- G03F 7/70625: {Dimensions, e.g. line width, critical dimension [CD], profile, sidewall angle or edge roughness}
- G03F 7/70941: {Stray fields and charges, e.g. stray light, scattered light, flare, transmission loss}
- 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

A low EUV reflectivity mask includes a low thermal expansion material (LTEM) layer, a low EUV reflectivity (LEUVR) multilayer over the LTEM layer in a first region, a high EUV reflectivity (HEUVR) multilayer over the LTEM layer in a second region and a patterned absorption layer over the LEUVR multilayer and the HEUVR multilayer.

## Claims

### Claim 1

A low extreme ultraviolet reflective (LEUVR) mask comprising:
a low thermal expansion material (LTEM) layer;
a low extreme ultraviolet reflectivity (LEUVR) multilayer over a first region of the LTEM layer;
a high extreme ultraviolet reflectivity (HEUVR) multilayer over a second region of the LTEM; and
a patterned absorption layer over the LEUVR multilayer and the HEUVR multilayer.

### Claim 2 (depends on 1)

The mask of claim 1, wherein the LEUVR multilayer has less than 2% EUV reflectivity.

### Claim 3 (depends on 1)

The mask of claim 1, wherein the HEUVR multilayer has more than 30% EUV reflectivity,

### Claim 4 (depends on 1)

The mask of claim 1, wherein the LEUVR multilayer includes forty film pairs, each film pair including a first film including about 1.5 nm molybdenum (Mo) and a second film including about 2 nm silicon (Si).

### Claim 5 (depends on 1)

The mask of claim 1, wherein the LEUVR multilayer includes forty film pairs, each film pair including a first film including about 4.5 nm molybdenum (Mo) and a second film including about 6 nm silicon (Si).

### Claim 6 (depends on 1)

The mask of claim 1, wherein the LEUVR multilayer includes a molybdenum silicon (MoSi) layer of about 280 nm thickness.

### Claim 7 (depends on 1)

The mask of claim 1, further comprising:
a capping layer over the LEUVR multilayer and the HEUVR multilayer.

### Claim 8 (depends on 7)

The mask of claim 7, wherein the capping layer includes about 2.5 nm thickness of ruthenium (Ru).

### Claim 9 (depends on 1)

The mask of claim 1, wherein the first region is surrounded by the second region.

### Claim 10 (depends on 1)

The mask of claim 1, wherein the patterned absorption layer includes about 70 nm thickness of tantalum boron nitride (TaBN).

### Claim 11 (depends on 1)

The mask of claim 1, wherein the patterned absorption layer includes about 56 nm thickness of tantalum boron nitride (TaBN) and about 14 nm thickness of tantalum boron oxide (TaBO) deposited over the TaBN layer.

### Claim 12 (depends on 1)

The mask of claim 1, wherein the HEUVR multilayer includes about forty pairs of films of about 3 nm thickness of molybdenum (Mo) and about 4 nm thickness of silicon (Si).

### Claim 13

An extreme ultraviolet lithography (EUVL) process comprising:
receiving a mask pair having at least one common pattern, the mask pair including:
an extreme ultraviolet (EUV) mask having a first EUV reflectivity r1; and
a low EUV reflectivity mask having a second EUV reflectivity r2;
receiving a substrate coated with a photoresist layer;
receiving an EUV scanner equipped with an EUV radiation;
performing a first exposure process to the substrate, by using the EUV scanner and the EUV mask, wherein the first exposure process is conducted according to a first exposure dose matrix; and
performing a second exposure process to the substrate, by using the EUV scanner and the low EUV reflectivity mask, wherein the second exposure process is conducted according to a second exposure dose matrix.

### Claim 14 (depends on 13)

The process of claim 13, wherein conducting the first exposure process according to the first exposure dose matrix is performed as:
exposing N regions of the substrate, each region (“n”, ranging from 1 to N) receives a different exposure dose according to the formula:
Eop−(n−1)Δ,
where Δ=r2/r1×Eop and Eop=an optimized exposure dose.

### Claim 15 (depends on 13)

The process of claim 13, wherein conducting the second exposure process according to the second exposure dose matrix is performed as:
exposing N regions of the substrate, each region (“n”, ranging from 1 to N) receives a different exposure dose according to the formula:
(n−1)Eop,

### Claim 16 (depends on 13)

The process of claim 13, wherein each region of the substrate receives a total exposure dose, which is a combination of the exposure dose received in the first and second exposure processes.

### Claim 17 (depends on 16)

The process of claim 16, wherein each region of the substrate receives substantial the same amount of exposure dose from the EUV radiation.

### Claim 18 (depends on 17)

The process of claim 17, wherein each region of the substrate receives a substantial different exposure dose from a deep ultraviolet (DUV) out of band (OOB) radiation of the EUV radiation.

### Claim 19 (depends on 17)

The process of claim 17, further comprising:
measuring critical dimensions (CDs) of each region of the substrate;
plotting a chart of CDs vs. a sum of the exposure doses of the first and second exposures to identify a trend line of CD vs. a DUV OOB radiation levels; and
using the chart, determining a DUV flare impact on the EUV mask exposed by the EUV scanner.

### Claim 20

A low extreme ultraviolet reflective (LEUVR) mask comprising:
a low thermal expansion material (LTEM) layer;
a first extreme ultraviolet reflectivity (EUVR) multilayer over the LTEM layer, having an EUV reflectivity larger than 30%;
a second extreme ultraviolet reflectivity (EUVR) multilayer over a portion of the first EUVR to form a third EUVR multilayer, which has the first EUVR as its bottom portion and the second EUVR as its upper portion, wherein the third EUVR multilayer has an EUV reflectivity less than 2%; and
a patterned absorption layer over the first EUVR multilayer and the second EUVR multilayer.