# US 11,531,263 B2 · Photomask having a plurality of shielding layers > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,531,263 B2 - Document ID: US11531263B2 - Status: Granted - Kind: B2 - Application number: 17/405,278 - Filed: 2021-08-18 - Published: 2021-12-02 - Granted: 2022-12-20 - Earliest claimed: 2016-04-12 - Assignees: Taiwan Semiconductor Manufacturing Company, Ltd. - Applicants: Taiwan Semiconductor Manufacturing Company, Ltd. - Inventors: Chih-Chiang Tu; Chun-Lang Chen - Web page: https://patentgrep.com/patent/US11531263B2 ## CPC - G03F 1/26: Phase shift masks [PSM]; PSM blanks; Preparation thereof - G03F 1/54: Absorbers, e.g. of opaque materials - 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 Some embodiments relate to photomask for mask patterning. The photomask includes a transparent layer comprising quartz, and a molybdenum silicide (MoSi) layer overlying the transparent layer. A first shielding layer overlies the MoSi layer and has a first thickness and a first optical density. A second shielding layer overlies the first shielding layer and has a second thickness and a second optical density. The second thickness is less than one third of the first thickness, and the second optical density is less than one fourth of the first optical density. An overall optical density of the first and second shielding layers is at least 1.8. ## Claims ### Claim 1 A photomask for mask patterning, comprising: a transparent layer comprising quartz; a molybdenum silicide (MoSi) layer overlying the transparent layer; a first shielding layer overlying the MoSi layer, wherein the first shielding layer has a first thickness and a first optical density; and a second shielding layer overlying the first shielding layer, wherein the second shielding layer has a second thickness less than one third of the first thickness and has a second optical density that is less than one fourth of the first optical density, and wherein an overall optical density of the first and second shielding layers is at least 1.8. ### Claim 2 (depends on 1) The photomask of claim 1, wherein the second shielding layer comprises chromium. ### Claim 3 (depends on 1) The photomask of claim 1, wherein the second shielding layer has a thickness of 3 nm to 7 nm. ### Claim 4 (depends on 1) The photomask of claim 1, wherein the first shielding layer comprises boron. ### Claim 5 (depends on 1) The photomask of claim 1, wherein the MoSi layer covers some portions of the transparent layer while leaving other portions of the transparent layer uncovered. ### Claim 6 (depends on 1) The photomask of claim 1, wherein the first shielding layer covers some portions of the MoSi layer but leaves other portions of the MoSi layer uncovered. ### Claim 7 (depends on 1) The photomask of claim 1, wherein the second shielding layer comprises chromium nitride. ### Claim 8 A photomask for mask patterning, comprising: a transparent layer comprising quartz; a molybdenum silicide (MoSi) layer overlying the transparent layer; a first shielding layer overlying the MoSi layer, the first shielding layer comprising a transition metal or a post transition metal, wherein the first shielding layer has a first thickness and a first optical density; and a second shielding layer overlying the first shielding layer and comprising chromium, wherein the second shielding layer has a second thickness less than one half of the first thickness and has a second optical density that is less than one half of the first optical density, and wherein an overall optical density of the first and second shielding layers is greater than 1.8. ### Claim 9 (depends on 8) The photomask of claim 8, wherein a total thickness of the first shielding layer and the second shielding layer ranges from approximately 19 nm to approximately 40 nm. ### Claim 10 (depends on 8) The photomask of claim 8, wherein a total thickness of the first shielding layer and the second shielding layer is approximately 29 nm. ### Claim 11 (depends on 8) The photomask of claim 8, wherein the second shielding layer comprises chromium nitride. ### Claim 12 (depends on 8) The photomask of claim 8, wherein the second shielding layer has a thickness of 3 nm to 7 nm. ### Claim 13 (depends on 8) The photomask of claim 8, wherein the second shielding layer covers some portions of the MoSi layer but leaves other portions of the MoSi layer uncovered. ### Claim 14 (depends on 8) The photomask of claim 8, wherein the first shielding layer comprises boron. ### Claim 15 A photomask for mask patterning, comprising: a transparent layer comprising quartz; a molybdenum silicide (MoSi) layer overlying the transparent layer; a first shielding layer overlying the MoSi layer, the first shielding layer having a first thickness and a first optical density; and a second shielding layer overlying the first shielding layer, the second shielding layer having a second thickness and a second optical density; wherein a thickness ratio of the first thickness to the second thickness is greater than 3:1, and an optical density ratio of the first optical density to the second optical density is greater than 4:1. ### Claim 16 (depends on 15) The photomask of claim 15, wherein an overall optical density of the first and second shielding layers is at least 1.8. ### Claim 17 (depends on 15) The photomask of claim 15, wherein the first optical density is greater than 1 and the second optical density is less than 1. ### Claim 18 (depends on 15) The photomask of claim 15, wherein the MoSi layer covers some portions of the transparent layer while leaving other portions of the transparent layer uncovered. ### Claim 19 (depends on 15) The photomask of claim 15, wherein the second shielding layer comprises chromium nitride. ### Claim 20 (depends on 15) The photomask of claim 15, wherein the first shielding layer comprises B5O15Ta3.