# US 2013/0280643 A1 · Reflective mask and method of making same

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- Number: US 2013/0280643 A1
- Document ID: US20130280643A1
- Status: Published application
- Kind: A1
- Application number: 13/451,705
- Filed: 2012-04-20
- Published: 2013-10-24
- Earliest claimed: 2012-04-20
- Assignees: Taiwan Semiconductor Manufacturing Company, Tld.
- Inventors: Pei-Cheng Hsu; Chih-Tsung Shih; Chia-Jen Chen; Tsiao-Chen Wu; Shinn-Sheng Yu; Hsin-Chang Lee; Anthony Yen
- Web page: https://patentgrep.com/patent/US20130280643A1

## CPC

- G03F 1/24: Reflection masks; Preparation thereof
- G03F 1/48: Protective coatings
- H10P 76/4085: {characterised by the processes involved to create the masks}
- 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)
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10

## Abstract

A reflective mask is described. The mask includes a low thermal expansion material (LTEM) substrate, a conductive layer deposited on a first surface of the LTEM substrate, a stack of reflective multilayers (ML) deposited on a second surface of the LTEM substrate, a capping layer deposited on the stack of reflective ML, a first absorption layer deposited on the first capping layer, a main pattern, and a border ditch. The border ditch reaches to the capping layer, the second absorption layer deposited inside the border ditch, and the second absorption layer contacts the capping layer.

## Claims

### Claim 1

A mask comprising:
a low thermal expansion material (LTEM) substrate;
a conductive layer deposited on a first surface of the LTEM substrate;
a stack of reflective multilayers (ML) deposited on a second surface of the LTEM substrate;
a capping layer deposited on the stack of reflective ML;
a first absorption layer deposited on the capping layer;
a main pattern and a border ditch, wherein the border ditch reaches to the capping layer; and
a second absorption layer in the border ditch.

### Claim 2 (depends on 1)

The mask of claim 1, further comprising a protection layer deposited on the second absorption layer, wherein the protection layer includes tantalum (Ta).

### Claim 3 (depends on 1)

The mask of claim 1, wherein the LTEM substrate includes one of fused silica, fused quartz, calcium fluoride (CaF2), silicon carbide, and silicon oxide-titanium oxide alloy.

### Claim 4 (depends on 1)

The mask of claim 1, wherein the conductive layer include chromium nitride (CrN).

### Claim 5 (depends on 1)

The mask of claim 1, wherein the stack of reflective ML includes a plurality of molybdenum-silicon (Mo/Si) film pairs or a plurality of molybdenum-beryllium (Mo/Be) film pairs.

### Claim 6 (depends on 1)

The mask of claim 1, wherein the capping layer includes a ruthenium-containing material.

### Claim 7 (depends on 1)

The mask of claim 1, wherein the first absorption layer includes a single layer or multiple layers from a group consisting of chromium (Cr), chromium oxide (CrO), titanium nitride (TiN), tantalum nitride (TaN), tantalum (Ta), titanium (Ti), aluminum-copper (Al—Cu), palladium, tantalum boron nitride (TaBN), aluminum oxide (AlO), and molybdenum (Mo).

### Claim 8 (depends on 1)

The mask of claim 1, wherein the second absorption layer deposited inside the border ditch contacts the capping layer.

### Claim 9 (depends on 1)

The method of claim 1, wherein the second absorption layer includes one of nickel (Ni), nickel phosphorus (NiP), silver oxide (AgxO), or a combination thereof.

### Claim 10

An extreme ultraviolet (EUV) mask, the EUV mask comprising:
a low thermal expansion material (LTEM) substrate;
a conductive layer deposited on a first surface of the LTEM substrate;
a stack of reflective multilayers (ML) deposited on a second surface of the LTEM substrate;
a capping layer deposited on the stack of reflective ML;
a first absorption layer deposited on the capping layer;
a main pattern and a border ditch, where in the border ditch crosses the capping layer and partially enters the partial stack of the reflective ML; and
a second absorption layer deposited in the border ditch.

### Claim 11 (depends on 10)

The EUV mask of claim 10, further comprising a protection layer deposited on the second absorption layer, wherein the protection layer includes one of tantalum (Ta), tantalum nitride (TaN), tantalum boron nitride (TaBN), or a combination thereof.

### Claim 12 (depends on 10)

The mask of claim 10, wherein the second absorption layer deposited inside the border ditch contacts the stack of reflective ML.

### Claim 13

A method for fabricating an extreme ultraviolet (EUV) mask, the method comprising:
receiving a low thermal expansion material (LTEM) substrate;
depositing a conductive layer on a first surface of the LTEM substrate;
depositing a stack of reflective multilayers (ML) on a second surface of the LTEM substrate;
depositing a capping layer on the stack of reflective ML;
depositing a first absorption layer on the capping layer;
forming a main pattern and a border ditch;
depositing resist in the border ditch to form a resist ditch; and
depositing a second absorption layer in the resist ditch.

### Claim 14 (depends on 13)

The method of claim 13, wherein the forming the main pattern and the border ditch includes depositing a first resist film on the first absorption layer, exposing the first resist film by an electron beam writer, and developing the exposed first resist film to form a first resist pattern.

### Claim 15 (depends on 14)

The method of claim 14, further comprising etching the first absorption layer and stopping etching at the capping layer so that the main pattern and the border ditch are formed.

### Claim 16 (depends on 14)

The method of claim 14, wherein forming the resist ditch includes depositing a second resist film on the pattern LTEM substrate, exposing the second resist film by an electron beam writer, and developing the exposed second resist film so that a second resist pattern is formed and the second resist pattern of the second resist film exposes the border ditch and protects the main pattern.

### Claim 17 (depends on 16)

The method of claim 16, further comprising etching the resist ditch so that the resist ditch enters a portion of the stack of reflective ML.

### Claim 18 (depends on 13)

The method of claim 13, wherein depositing the second absorption layer includes depositing the second absorption layer into the resist ditch.

### Claim 19 (depends on 18)

The method of claim 18, further comprising depositing a protection layer on the second absorption layer in the resist ditch.

### Claim 20 (depends on 16)

The method of claim 16, further comprising stripping the second resist film by a lift-off process.