# US 10,481,483 B2 · Lithography mask and method

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 10,481,483 B2
- Document ID: US10481483B2
- Status: Granted
- Kind: B2
- Application number: 15/816,393
- Filed: 2017-11-17
- Published: 2019-01-03
- Granted: 2019-11-19
- Earliest claimed: 2017-06-30
- Assignees: Taiwan Semiconductor Manufacturing Company, Ltd.
- Applicants: Taiwan Semiconductor Manufacturing Company, Ltd.
- Inventors: Shiang-Bau Wang; Syun-Ming Jang
- Web page: https://patentgrep.com/patent/US10481483B2

## CPC

- G03F 1/24: Reflection masks; Preparation thereof
- G03F 1/40: Electrostatic discharge [ESD] related features, e.g. antistatic coatings or a conductive metal layer around the periphery of the mask substrate
- G03F 1/42: Alignment or registration features, e.g. alignment marks on the mask substrates
- G03F 1/46: Antireflective coatings
- G03F 1/52: Reflectors
- G03F 1/76: Patterning of masks by imaging
- G03F 1/80: Etching
- G03F 7/2008: {characterised by the reflectors, diffusers, light or heat filtering means or anti-reflective means used}
- H10P 76/2043: {using an anti-reflective coating}
- 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

In an embodiment, a photomask includes: a substrate over a first conductive layer, the substrate formed of a low thermal expansion material (LTEM); a second conductive layer over the first conductive layer; a reflective film stack over the substrate; a capping layer over the reflective film stack; an absorption layer over the capping layer; and an antireflection (ARC) layer over the absorption layer, where the ARC layer and the absorption layer have a plurality of openings in a first region exposing the capping layer, where the ARC layer, the absorption layer, the capping layer, and the reflective film stack have a trench in a second region exposing the second conductive layer.

## Claims

### Claim 1

A photomask comprising:
a substrate over a first conductive layer, the substrate formed of a low thermal expansion material (LTEM);
a second conductive layer over the first conductive layer;
a reflective film stack over the substrate;
a capping layer over the reflective film stack;
an absorption layer over the capping layer; and
an antireflection (ARC) layer over the absorption layer, wherein the ARC layer and the absorption layer have a plurality of openings in a first region exposing the capping layer, wherein the ARC layer, the absorption layer, the capping layer, and the reflective film stack have a trench in a second region exposing the second conductive layer.

### Claim 2 (depends on 1)

The photomask of claim 1, further comprising:
a conductive film stack between the substrate and the reflective film stack, the conductive film stack comprising a plurality of conductive layers, the plurality of conductive layers including the second conductive layer.

### Claim 3 (depends on 2)

The photomask of claim 2, wherein a bottommost layer of the reflective film stack physically contacts a topmost layer of the conductive film stack.

### Claim 4 (depends on 1)

The photomask of claim 1, wherein a bottommost layer of the reflective film stack physically contacts the substrate.

### Claim 5 (depends on 4)

The photomask of claim 4, wherein the second conductive layer is a doped region in a top surface of the substrate, the doped region being doped with B or P.

### Claim 6 (depends on 4)

The photomask of claim 4, wherein the second conductive layer is disposed along a top surface of the substrate, and along sides of the reflective film stack, the capping layer, the absorption layer, and the ARC layer.

### Claim 7 (depends on 1)

The photomask of claim 1, wherein the trench surrounds the first region.

### Claim 8 (depends on 1)

The photomask of claim 1, wherein the reflective film stack comprises alternating layers of a first material and a second material, the first material having a higher refractive index than the second material.

### Claim 9 (depends on 8)

The photomask of claim 8, wherein the reflective film stack has from 20 to 80 pairs of the first and second materials, the first material is Si, and the second material is Mo.

### Claim 10 (depends on 1)

The photomask of claim 1, wherein the second conductive layer and the absorption layer are formed of the same material.

### Claim 11 (depends on 1)

The photomask of claim 1, wherein the second conductive layer comprises B or P.

### Claim 12

A photomask comprising:
a first conductive layer over a second conductive layer;
a reflective film stack over the first conductive layer, the reflective film stack comprising alternating layers of a first material and a second material, the first material having a higher refractive index than the second material;
a capping layer over the reflective film stack;
an absorption layer over the capping layer; and
an antireflection (ARC) layer over the absorption layer, wherein the ARC layer and the absorption layer have a plurality of openings exposing the capping layer, wherein the ARC layer, the absorption layer, the capping layer, and the reflective film stack have a trench exposing the first conductive layer and surrounding the openings.

### Claim 13 (depends on 12)

The photomask of claim 12, further comprising:
a conductive film stack over the first conductive layer, the conductive film stack comprising a plurality of conductive layers, the plurality of conductive layers including the first conductive layer, wherein the reflective film stack is disposed over the conductive film stack.

### Claim 14 (depends on 12)

The photomask of claim 12, wherein portions of the first conductive layer exposed by the trench are absorptive.

### Claim 15

A method comprising:
forming a first conductive layer over a substrate;
forming a reflective film stack over the substrate, the reflective film stack comprising alternating layers of a first material and a second material, the first material having a higher refractive index than the second material;
depositing a capping layer over the reflective film stack;
depositing an absorption layer over the capping layer;
depositing an antireflection (ARC) layer over the absorption layer;
patterning a plurality of first openings extending through the ARC layer and the absorption layer; and
patterning a trench extending through the ARC layer, the absorption layer, the capping layer, and the reflective film stack, wherein the trench surrounds the first openings and exposes the first conductive layer.

### Claim 16 (depends on 15)

The method of claim 15, wherein forming the reflective film stack over the substrate comprises forming the reflective film stack over the first conductive layer.

### Claim 17 (depends on 15)

The method of claim 15, further comprising:
forming a photoresist over the ARC layer;
patterning the photoresist with a second opening;
etching the ARC layer, the absorption layer, the capping layer, and the reflective film stack using the patterned photoresist as an etching mask to form the trench;
implanting dopants in the substrate using the patterned photoresist as an implantation mask to form the first conductive layer; and
removing the patterned photoresist.

### Claim 18 (depends on 15)

The method of claim 15, further comprising:
forming a photoresist over the ARC layer;
patterning the photoresist with a second opening;
etching the ARC layer, the absorption layer, the capping layer, and the reflective film stack using the patterned photoresist as an etching mask to form the trench;
depositing the first conductive layer over the photoresist and in the trench; and
removing the patterned photoresist and portions of the first conductive layer over the photoresist.

### Claim 19 (depends on 15)

The method of claim 15, wherein portions of the first conductive layer exposed by the trench are non-reflective.

### Claim 20 (depends on 16)

The method of claim 16, further comprising:
projecting a radiation beam toward the reflective film stack such that the radiation beam is reflected from the reflective film stack and onto a photosensitive material, the radiation beam having a pattern corresponding to the pattern of the first openings.