# US 8,785,085 B2 · Method of manufacturing a mask blank substrate, method of manufacturing a mask blank, method of manufacturing a transfer mask, and method of manufacturing a semiconductor device > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,785,085 B2 - Document ID: US8785085B2 - Status: Granted - Kind: B2 - Application number: 13/638,505 - Filed: 2011-03-29 - Published: 2013-01-24 - Granted: 2014-07-22 - Earliest claimed: 2010-03-30 - Assignees: Hoya Corporation - Applicants: Masaru Tanabe - Inventors: Masaru Tanabe - Web page: https://patentgrep.com/patent/US8785085B2 ## CPC - G03F 1/50: Mask blanks not covered by G03F1/20 - G03F1/34; Preparation thereof - G03F 1/70: Adapting basic layout or design of masks to lithographic process requirements, e.g., second iteration correction of mask patterns for imaging - 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 In a simulation step of simulating a surface configuration of a substrate which is used for a mask blank and which is set to an exposure apparatus, height information from a reference plane is derived from a plurality of measurement points on a main surface of the substrate. From the height information, a curved surface of fourth, fifth, or sixth order is approximated which is represented by a polynomial specified by a plurality of terms and coefficients of the terms. The coefficients are stored as coefficient information in association with the substrate. ## Claims ### Claim 1 A method of manufacturing a mask blank substrate, comprising: a preparation step of preparing a transparent substrate having a precision-polished main surface; a shape measurement step of measuring height information of the main surface from a reference plane at a plurality of measurement points set in an actual measurement region of the main surface, thereby obtaining a before-chucking main surface shape; a simulation step of obtaining, through simulation, an after-chucking main surface shape which is height information of the main surface from the reference plane at the plurality of measurement points when the transparent substrate is chucked on a mask stage of an exposure apparatus; an approximate curved surface calculation step of calculating an approximate curved surface based on the after-chucking main surface shape; and a recording step of recording information of the approximate curved surface in a recording apparatus in association with the transparent substrate. ### Claim 2 (depends on 1) The method of manufacturing a mask blank substrate according to claim 1, wherein the approximate curved surface is given by a function of several variables expressed by a three-dimensional coordinate system which is obtained by setting an X-coordinate axis and a Y-coordinate axis on the reference plane and setting a Z-coordinate axis in a direction perpendicular to the reference plane, and the recording step records information of coefficients of the function of several variables as the information of the approximate curved surface in the recording apparatus. ### Claim 3 (depends on 2) The method of manufacturing a mask blank substrate according to claim 2, wherein the approximate curved surface is given by the function of several variables in which X or Y is of fourth or higher degree. ### Claim 4 (depends on 2) The method of manufacturing a mask blank substrate according to claim 2, further comprising a partial differential function calculation step of calculating an X partial differential function by partially differentiating the function of several variables with respect to X and calculating a Y partial differential function by partially differentiating the function of several variables with respect to Y, wherein the recording step also records information of coefficients of the X partial differential function and the Y partial differential function as information of the approximate curved surface in the recording apparatus. ### Claim 5 (depends on 1) The method of manufacturing a mask blank substrate according to claim 1, wherein the simulation step comprises: calculating a gravity deformation amount which is a deformation amount of the main surface caused by gravity when the transparent substrate is placed on the mask stage; calculating a lever deformation amount which is caused by lever deformation of the main surface with respect to the mask stage operable as a fulcrum when the transparent substrate is chucked on the mask stage, a copy deformation amount which is caused by deformation of the main surface following a shape of the mask stage when the transparent substrate is chucked on the mask stage, and a twist deformation amount which is caused by deformation of the main surface that corrects twist thereof when the transparent substrate is chucked on the mask stage; and calculating the after-chucking main surface shape by adding the calculated deformation amounts to the before-chucking main surface shape. ### Claim 6 (depends on 1) The method of manufacturing a mask blank substrate according to claim 1, comprising a selection step of selecting, as a mask blank substrate, the transparent substrate whose flatness in a calculation region obtained from the after-chucking main surface shape is a predetermined value or less. ### Claim 7 (depends on 6) The method of manufacturing a mask blank substrate according to claim 6, wherein the calculation region is a 132 mm square region with respect to a center of the transparent substrate. ### Claim 8 (depends on 6) The method of manufacturing a mask blank substrate according to claim 6, wherein the predetermined value of the flatness is 0.24 μm or less. ### Claim 9 (depends on 1) The method of manufacturing a mask blank substrate according to claim 1, comprising a step of selecting the transparent substrate whose flatness in a predetermined region obtained from the before-chucking main surface shape is 0.4 μm or less. ### Claim 10 (depends on 1) A method of manufacturing a mask blank, comprising a thin film forming step of forming a pattern-formation thin film on the main surface of the mask blank substrate manufactured by the method of manufacturing a mask blank substrate according to claim 1. ### Claim 11 (depends on 10) A method of manufacturing a transfer mask using the mask blank manufactured by the method of manufacturing a mask blank according to claim 10, comprising: a resist film forming step of forming a resist film on the pattern-formation thin film of the mask blank; a pattern correction step of correcting a transfer pattern, to be formed in the resist film, based on the information of the approximate curved surface; and a resist pattern forming step of forming, in the resist film, the transfer pattern corrected in the pattern correction step. ### Claim 12 (depends on 11) A method of manufacturing a semiconductor device, comprising a step of, by the use of the transfer mask manufactured by the method of manufacturing a transfer mask according to claim 11, exposing and transferring the transfer pattern of the transfer mask to a resist film on a wafer by photolithography. ### Claim 13 (depends on 1) A method of manufacturing a mask blank, comprising a thin film forming step of forming a pattern-formation thin film on the main surface of the mask blank substrate manufactured by the method of manufacturing a mask blank substrate according to claim 1. ### Claim 14 (depends on 13) A method of manufacturing a transfer mask using the mask blank manufactured by the method of manufacturing a mask blank according to claim 13, comprising: a resist film forming step of forming a resist film on the pattern-formation thin film of the mask blank; a pattern correction step of correcting a transfer pattern, to be formed in the resist film, based on the information of the approximate curved surface; and a resist pattern forming step of forming, in the resist film, the transfer pattern corrected in the pattern correction step. ### Claim 15 (depends on 14) A method of manufacturing a semiconductor device, comprising a step of, by the use of the transfer mask manufactured by the method of manufacturing a transfer mask according to claim 14, exposing and transferring the transfer pattern of the transfer mask to a resist film on a wafer by photolithography. ### Claim 16 A method of manufacturing a mask blank substrate, comprising: a preparation step of preparing a transparent substrate having a precision-polished main surface; a shape measurement step of measuring height information of the main surface from a reference plane at a plurality of measurement points set in an actual measurement region of the main surface, thereby obtaining a before-chucking main surface shape; a simulation step of obtaining, through simulation, an after-chucking main surface shape which is height information of the main surface from the reference plane at the plurality of measurement points when the transparent substrate is chucked on a mask stage of an exposure apparatus; an approximate curved surface calculation step of calculating, based on the after-chucking main surface shape, an approximate curved surface given by a function of several variables expressed by a three-dimensional coordinate system which is obtained by setting an X-coordinate axis and a Y-coordinate axis on the reference plane and setting a Z-coordinate axis in a direction perpendicular to the reference plane; a partial differential function calculation step of calculating an X partial differential function by partially differentiating the function of several variables with respect to X and calculating a Y partial differential function by partially differentiating the function of several variables with respect to Y; and a recording step of recording information of coefficients of the X partial differential function and the Y partial differential function as information of the approximate curved surface in a recording apparatus in association with the transparent substrate. ### Claim 17 (depends on 16) The method of manufacturing a mask blank substrate according to claim 16, wherein the approximate curved surface is given by the function of several variables in which X or Y is of fourth or higher degree. ### Claim 18 (depends on 16) The method of manufacturing a mask blank substrate according to claim 16, wherein the simulation step comprises: calculating a gravity deformation amount which is a deformation amount of the main surface caused by gravity when the transparent substrate is placed on the mask stage; calculating a lever deformation amount which is caused by lever deformation of the main surface with respect to the mask stage operable as a fulcrum when the transparent substrate is chucked on the mask stage, a copy deformation amount which is caused by deformation of the main surface following a shape of the mask stage when the transparent substrate is chucked on the mask stage, and a twist deformation amount which is caused by deformation of the main surface that corrects twist thereof when the transparent substrate is chucked on the mask stage; and calculating the after-chucking main surface shape by adding the calculated deformation amounts to the before-chucking main surface shape. ### Claim 19 A method of manufacturing a mask blank, comprising: a preparation step of preparing a mask blank having a thin film on a main surface of a transparent substrate; a shape measurement step of measuring height information of a main surface of the mask blank from a reference plane at a plurality of measurement points set in an actual measurement region of the main surface, thereby obtaining a before-chucking main surface shape; a simulation step of obtaining, through simulation, an after-chucking main surface shape which is height information of the main surface from the reference plane at the plurality of measurement points when the mask blank is chucked on a mask stage of an exposure apparatus; an approximate curved surface calculation step of calculating an approximate curved surface based on the after-chucking main surface shape; and a recording step of recording information of the approximate curved surface in a recording apparatus in association with the mask blank. ### Claim 20 (depends on 19) The method of manufacturing a mask blank according to claim 19, wherein: the approximate curved surface is given by a function of several variables expressed by a three-dimensional coordinate system which is obtained by setting an X-coordinate axis and a Y-coordinate axis on the reference plane and setting a Z-coordinate axis in a direction perpendicular to the reference plane, and the recording step records information of coefficients of the function of several variables as the information of the approximate curved surface in the recording apparatus. ### Claim 21 (depends on 20) The method of manufacturing a mask blank according to claim 20, wherein the approximate curved surface is given by the function of several variables in which X or Y is of fourth or higher degree. ### Claim 22 (depends on 20) The method of manufacturing a mask blank according to claim 20, further comprising: a partial differential function calculation step of calculating an X partial differential function by partially differentiating the function of several variables with respect to X and calculating a Y partial differential function by partially differentiating the function of several variables with respect to Y, wherein the recording step also records information of coefficients of the X partial differential function and the Y partial differential function as information of the approximate curved surface in the recording apparatus. ### Claim 23 (depends on 19) The method of manufacturing a mask blank according to claim 19, wherein the simulation step comprises: calculating a gravity deformation amount which is a deformation amount of the main surface caused by gravity when the mask blank is placed on the mask stage; calculating a lever deformation amount which is caused by lever deformation of the main surface with respect to the mask stage operable as a fulcrum when the mask blank is chucked on the mask stage, a copy deformation amount which is caused by deformation of the main surface following a shape of the mask stage when the mask blank is chucked on the mask stage, and a twist deformation amount which is caused by deformation of the main surface that corrects twist thereof when the mask blank is chucked on the mask stage; and calculating the after-chucking main surface shape by adding the calculated deformation amounts to the before-chucking main surface shape. ### Claim 24 (depends on 19) The method of manufacturing a mask blank according to claim 19, comprising a selection step of selecting the mask blank whose flatness in a calculation region obtained from the after-chucking main surface shape is a predetermined value or less. ### Claim 25 (depends on 24) The method of manufacturing a mask blank according to claim 24, wherein the calculation region is a 132 mm square region with respect to a center of the transparent substrate. ### Claim 26 (depends on 24) The method of manufacturing a mask blank according to claim 24, wherein the predetermined value of the flatness is 0.24 μm or less. ### Claim 27 (depends on 19) The method of manufacturing a mask blank according to claim 19, comprising a step of selecting the mask blank whose flatness in a predetermined region obtained from the before-chucking main surface shape is 0.4 μm or less. ### Claim 28 (depends on 19) A method of manufacturing a transfer mask using the mask blank manufactured by the method of manufacturing a mask blank according to claim 19, comprising: a resist film forming step of forming a resist film on the pattern-formation thin film of the mask blank; a pattern correction step of correcting a transfer pattern, to be formed in the resist film, based on the information of the approximate curved surface; and a resist pattern forming step of forming, in the resist film, the transfer pattern corrected in the pattern correction step. ### Claim 29 (depends on 28) A method of manufacturing a semiconductor device, comprising a step of, by the use of the transfer mask manufactured by the method of manufacturing a transfer mask according to claim 28, exposing and transferring the transfer pattern of the transfer mask to a resist film on a wafer by photolithography. ### Claim 30 A method of manufacturing a mask blank, comprising: a preparation step of preparing a mask blank having a thin film on a main surface of a transparent substrate; a shape measurement step of measuring height information of a main surface of the mask blank from a reference plane at a plurality of measurement points set in an actual measurement region of the main surface, thereby obtaining a before-chucking main surface shape; a simulation step of obtaining, through simulation, an after-chucking main surface shape which is height information of the main surface from the reference plane at the plurality of measurement points when the mask blank is chucked on a mask stage of an exposure apparatus; an approximate curved surface calculation step of calculating, based on the after-chucking main surface shape, an approximate curved surface given by a function of several variables expressed by a three-dimensional coordinate system which is obtained by setting an X-coordinate axis and a Y-coordinate axis on the reference plane and setting a Z-coordinate axis in a direction perpendicular to the reference plane; a partial differential function calculation step of calculating an X partial differential function by partially differentiating the function of several variables with respect to X and calculating a Y partial differential function by partially differentiating the function of several variables with respect to Y; and a recording step of recording information of coefficients of the X partial differential function and the Y partial differential function as information of the approximate curved surface in a recording apparatus in association with the transparent substrate. ### Claim 31 (depends on 30) The method of manufacturing a mask blank according to claim 30, wherein the approximate curved surface is given by the function of several variables in which X or Y is of fourth or higher degree. ### Claim 32 (depends on 30) The method of manufacturing a mask blank according to claim 30, wherein the simulation step comprises: calculating a gravity deformation amount which is a deformation amount of the main surface caused by gravity when the mask blank is placed on the mask stage; calculating a lever deformation amount which is caused by lever deformation of the main surface with respect to the mask stage operable as a fulcrum when the mask blank is chucked on the mask stage, a copy deformation amount which is caused by deformation of the main surface following a shape of the mask stage when the mask blank is chucked on the mask stage, and a twist deformation amount which is caused by deformation of the main surface that corrects twist thereof when the mask blank is chucked on the mask stage; and calculating the after-chucking main surface shape by adding the calculated deformation amounts to the before-chucking main surface shape. ### Claim 33 (depends on 32) A method of manufacturing a transfer mask using the mask blank manufactured by the method of manufacturing a mask blank according to claim 32, comprising: a resist film forming step of forming a resist film on the pattern-formation thin film of the mask blank; a pattern correction step of correcting a transfer pattern, to be formed in the resist film, based on the information of the approximate curved surface; and a resist pattern forming step of forming, in the resist film, the transfer pattern corrected in the pattern correction step. ### Claim 34 (depends on 33) A method of manufacturing a semiconductor device, comprising a step of, by the use of the transfer mask manufactured by the method of manufacturing a transfer mask according to claim 33, exposing and transferring the transfer pattern of the transfer mask to a resist film on a wafer by photolithography. ### Claim 35 A method of manufacturing a transfer mask, comprising: a preparation step of preparing a mask blank having a thin film on a main surface of a transparent substrate; a shape measurement step of measuring height information of a main surface of the mask blank from a reference plane at a plurality of measurement points set in an actual measurement region of the main surface, thereby obtaining a before-chucking main surface shape; a simulation step of obtaining, through simulation, an after-chucking main surface shape which is height information of the main surface from the reference plane at the plurality of measurement points when the mask blank is chucked on a mask stage of an exposure apparatus; an approximate curved surface calculation step of calculating an approximate curved surface based on the after-chucking main surface shape; a resist film forming step of forming a resist film on the pattern-formation thin film of the mask blank; a pattern correction step of correcting a transfer pattern, to be formed in the resist film, based on information of the approximate curved surface; and a resist pattern forming step of forming, in the resist film, the transfer pattern corrected in the pattern correction step. ### Claim 36 (depends on 35) The method of manufacturing a transfer mask according to claim 35, wherein the approximate curved surface is given by a function of several variables expressed by a three-dimensional coordinate system which is obtained by setting an X-coordinate axis and a Y-coordinate axis on the reference plane and setting a Z-coordinate axis in a direction perpendicular to the reference plane. ### Claim 37 (depends on 36) The method of manufacturing a transfer mask according to claim 36, wherein the approximate curved surface is given by the function of several variables in which X or Y is of fourth or higher degree. ### Claim 38 (depends on 36) The method of manufacturing a transfer mask according to claim 36, comprising a partial differential function calculation step of calculating an X partial differential function by partially differentiating the function of several variables with respect to X and calculating a Y partial differential function by partially differentiating the function of several variables with respect to Y. ### Claim 39 (depends on 35) The method of manufacturing a transfer mask according to claim 35, wherein the simulation step comprises: calculating a gravity deformation amount which is a deformation amount of the main surface caused by gravity when the mask blank is placed on the mask stage; calculating a lever deformation amount which is caused by lever deformation of the main surface with respect to the mask stage operable as a fulcrum when the mask blank is chucked on the mask stage, a copy deformation amount which is caused by deformation of the main surface following a shape of the mask stage when the mask blank is chucked on the mask stage, and a twist deformation amount which is caused by deformation of the main surface that corrects twist thereof when the mask blank is chucked on the mask stage; and calculating the after-chucking main surface shape by adding the calculated deformation amounts to the before-chucking main surface shape. ### Claim 40 (depends on 35) The method of manufacturing a transfer mask according to claim 35, comprising a selection step of selecting the mask blank whose flatness in a calculation region obtained from the after-chucking main surface shape is a predetermined value or less. ### Claim 41 (depends on 40) The method of manufacturing a transfer mask according to claim 40, wherein the calculation region is a 132 mm square region with respect to a center of the transparent substrate. ### Claim 42 (depends on 40) The method of manufacturing a transfer mask according to claim 40, wherein the predetermined value of the flatness is 0.24 μm or less. ### Claim 43 (depends on 35) The method of manufacturing a transfer mask according to claim 35, comprising a step of selecting the mask blank whose flatness in a predetermined region obtained from the before-chucking main surface shape is 0.4 μm or less. ### Claim 44 (depends on 35) A method of manufacturing a semiconductor device, comprising a step of, by the use of the transfer mask manufactured by the method of manufacturing a transfer mask according to claim 35, exposing and transferring the transfer pattern of the transfer mask to a resist film on a wafer by photolithography.