# US 11,029,595 B2 · Mask assembly and associated methods > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,029,595 B2 - Document ID: US11029595B2 - Status: Granted - Kind: B2 - Application number: 16/707,201 - Filed: 2019-12-09 - Published: 2020-04-16 - Granted: 2021-06-08 - Earliest claimed: 2015-02-03 - Assignees: ASML Netherlands B.V. - Applicants: ASML Netherlands B.V. - Inventors: Derk Servatius Gertruda Brouns; Dennis De Graaf; Robertus Cornelis Martinus De Kruif; Paul Janssen; Matthias Kruizinga; Arnoud Willem Notenboom; Daniel Andrew Smith; Beatrijs Louise Marie-Joseph Katrien Verbrugge; James Norman Wiley - Web page: https://patentgrep.com/patent/US11029595B2 ## CPC - G03F 1/62: Pellicles, e.g. pellicle assemblies, e.g. having membrane on support frame; Preparation thereof - G03F 1/38: Masks having auxiliary features, e.g. special coatings or marks for alignment or testing; Preparation thereof - G03F 1/66: Containers specially adapted for masks, mask blanks or pellicles; Preparation thereof - G03F 7/70983: {Optical system protection, e.g. pellicles or removable covers for protection of mask} - G03F 1/22: Masks or mask blanks for imaging by radiation of 100nm or shorter wavelength, e.g. X-ray masks, extreme ultraviolet [EUV] masks; Preparation thereof - G03F 1/42: Alignment or registration features, e.g. alignment marks on the mask substrates - G03F 1/64: characterised by the frames, e.g. structure or material, including bonding means therefor - G03F 1/84: Inspecting - 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 method comprising the steps of receiving a mask assembly comprising a mask and a removable EUV transparent pellicle held by a pellicle frame, removing the pellicle frame and EUV transparent pellicle from the mask, using an inspection tool to inspect the mask pattern on the mask, and subsequently attaching to the mask an EUV transparent pellicle held by a pellicle frame. The method may also comprise the following steps: after removing the pellicle frame and EUV transparent pellicle from the mask, attaching to the mask an alternative pellicle frame holding an alternative pellicle formed from a material which is substantially transparent to an inspection beam of the inspection tool; and after using an inspection tool to inspect the mask pattern on the mask, removing the alternative pellicle held by the alternative pellicle frame from the mask in order to attach to the mask the EUV transparent pellicle held by the pellicle frame. ## Claims ### Claim 1 A mask assembly container comprising an opening through which a mask assembly may be placed inside the container, and a seal that seals shut the opening when the mask assembly is located inside the container, wherein the container has a floor configured to accommodate outward sagging of a pellicle. ### Claim 2 (depends on 1) The mask assembly container of claim 1, wherein the floor is between 0.5 mm and 1 mm or more away from a pellicle plane when the mask assembly is held in the sealed container. ### Claim 3 A pellicle assembly container comprising an opening through which a pellicle assembly may be placed inside the container, and a seal that seals shut the opening when the pellicle assembly is located inside the container, wherein the container has a floor configured to accommodate outward sagging of a pellicle. ### Claim 4 (depends on 3) The pellicle assembly container of claim 3, wherein the floor is between 0.5 mm and 1 mm or more away from a pellicle plane when the mask assembly is held in the sealed container. ### Claim 5 A pellicle assembly comprising a pellicle membrane extending from a substrate border portion, a support frame attached to the substrate border portion, a first cover and a second cover, wherein the first and second covers are provided on opposite sides of the substrate border portion and form a sealed environment which contains the pellicle membrane. ### Claim 6 (depends on 5) The pellicle assembly of claim 5, wherein the second cover covers the support frame such that the support frame is located within the sealed environment. ### Claim 7 (depends on 5) The pellicle assembly of claim 5, wherein the first and second covers are clamped against the substrate border portion. ### Claim 8 A method of making a pellicle assembly, the method comprising: forming a membrane on a substrate and etching away substrate material to expose the membrane and thereby provide a pellicle membrane supported by a substrate perimeter; attaching a support frame to a portion of the substrate that borders the membrane; and providing a first cover on one side of the substrate and a second cover on an opposite side of the substrate and clamping them together to form a sealed environment that contains the pellicle membrane. ### Claim 9 (depends on 8) The method of claim 8, wherein the first cover is clamped against the substrate. ### Claim 10 (depends on 8) The method of claim 8, wherein the second cover is clamped against the substrate. ### Claim 11 (depends on 8) The method of claim 8, wherein the method further comprises cutting away parts of the substrate which project beyond the first and second covers. ### Claim 12 (depends on 8) The method of claim 8, wherein the forming a membrane on a substrate comprises forming the membrane on a silicon wafer. ### Claim 13 (depends on 8) The method of claim 8, wherein the second cover is oriented to cover the support frame such that the support frame is located within the sealed environment. ### Claim 14 (depends on 8) The method of claim 8, wherein the first cover is formed with a recess configured to accommodate sagging of the pellicle membrane. ### Claim 15 (depends on 8) The method of claim 8, wherein the method is performed at a pellicle manufacturing location. ### Claim 16 (depends on 8) The method of claim 8, further comprising forming a mask assembly by: attaching a pellicle location tool to the support frame; removing the second cover from the pellicle assembly; attaching the support frame to a mask; and removing the first cover from the pellicle assembly using the pellicle location tool. ### Claim 17 (depends on 16) The method of claim 16, wherein the pellicle location tool includes arms that are received in blind holes provided in the support frame. ### Claim 18 (depends on 16) The method of claim 16, wherein that method is performed at a mask shop. ### Claim 19 (depends on 16) The method of claim 16, wherein the method further comprises putting the mask assembly inside a container and sealing that container.