Mask blank, transfer mask manufacturing method, and display device manufacturing method

Abstract

To provide a mask blank which can prevent an etch mask film from being peeled off by a chemical used for cleaning or the like.SOLUTION: There is provided a mask blank obtained by laminating a pattern forming thin film and an etching mask film in this order on the main surface of a translucent substrate, wherein the thin film contains metal, silicon and nitrogen and the etching mask film contains chromium, the thickness of the etching mask film at the outer periphery of the etching mask film is smaller than the thickness of the etching mask film at the part other than the outer periphery of the etching mask film and the ratio of the nitrogen content to the silicon content at the outer periphery of the thin film is larger than the ratio of the nitrogen content to the silicon content at the part other than the outer periphery of the thin film.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a mask blank, a transfer mask, a method for manufacturing a mask blank, a method for manufacturing a transfer mask, and a method for manufacturing a display device. [Background technology]

[0002] In recent years, display devices such as LCDs (Liquid Crystal Displays) and other FPDs (Flat Panel Displays) have rapidly become larger in screen size and wider in viewing angle, while also achieving higher resolution and faster display speeds. One of the elements required for achieving this higher resolution and faster display speed is the fabrication of fine, highly dimensionally accurate electronic circuit patterns for elements, wiring, and other components. Photolithography is often used to pattern the electronic circuits for these display devices. This has created a need for phase-shift masks for display device manufacturing that have fine, highly accurate patterns formed on them.

[0003] For example, Patent Document 1 discloses a phase shift mask blank comprising a light-transmitting substrate, a semi-transparent film made of a metal silicide-based material formed on a main surface of the light-transmitting substrate, and an etching mask film made of a chromium-based material formed on the semi-transparent film, in which a compositionally graded region P is formed at the interface between the semi-transparent film and the etching mask film, and in this compositionally graded region P, the proportion of a component that slows the wet etching rate of the semi-transparent film increases stepwise and / or continuously in the depth direction, and a phase shift mask manufactured using this phase shift mask blank. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 6101646 Summary of the Invention [Problem to be solved by the invention]

[0005] Generally, mask blanks are cleaned with chemicals during the manufacturing process. Furthermore, the process of manufacturing a transfer mask from this mask blank also involves cleaning with chemicals. However, when a mask blank having a structure in which a thin film made of a metal silicide nitride-based material and an etching mask film made of a chromium-based material are stacked in this order on a light-transmitting substrate as described above is cleaned with chemicals, the etching mask film on the periphery sometimes peels off from the thin film. This problem is particularly likely to occur with etching mask films formed using an inline sputtering system.

[0006] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a mask blank, a method for manufacturing a transfer mask, and a method for manufacturing a display device that can suppress the phenomenon of peeling of an etching mask film when a cleaning process using a chemical solution is performed. [Means for solving the problem]

[0007] The present invention has the following configuration as a means for solving the above problems.

[0008] (Configuration 1) A mask blank in which a pattern-forming thin film and an etching mask film are laminated in this order on a main surface of a light-transmitting substrate, the thin film contains a metal, silicon, and nitrogen; the etching mask film contains chromium, a thickness of the etching mask film at a peripheral portion thereof is smaller than a thickness of the etching mask film at a portion other than the peripheral portion thereof; The ratio of the nitrogen content to the silicon content in the outer periphery of the thin film is greater than the ratio of the nitrogen content to the silicon content in the portion of the thin film other than the outer periphery. A mask blank characterized by:

[0009] (Configuration 2) The mask blank according to configuration 1, characterized in that a ratio calculated by dividing the ratio of the nitrogen content to the silicon content in the outer peripheral portion of the thin film by the ratio of the nitrogen content to the silicon content in the portion of the thin film other than the outer peripheral portion is 1.1 or more.

[0010] (Configuration 3) 3. The mask blank according to claim 1, wherein the oxygen content of the thin film is 10 atomic % or less.

[0011] (Configuration 4) 4. The mask blank according to any one of configurations 1 to 3, wherein the total content of metal, silicon, and nitrogen in the thin film is 90 atomic % or more.

[0012] (Configuration 5) 5. The mask blank according to any one of configurations 1 to 4, wherein the thin film contains at least molybdenum.

[0013] (Configuration 6) 6. The mask blank according to any one of configurations 1 to 5, wherein the etching mask film has a columnar structure in at least a portion in the thickness direction.

[0014] (Configuration 7) 7. The mask blank according to any one of configurations 1 to 6, wherein the thin film has a columnar structure in at least a portion in the thickness direction.

[0015] (Configuration 8) 8. The mask blank according to any one of configurations 1 to 7, wherein the film thickness of the thin film in the outer periphery is smaller than the film thickness in the other portions of the thin film.

[0016] (Configuration 9) the thin film is a phase shift film, 9. The mask blank according to any one of configurations 1 to 8, wherein a portion of the phase shift film other than the outer peripheral portion has a transmittance of 3% or more for light with a wavelength of 365 nm and a phase difference of 150 degrees or more and 210 degrees or less for light with a wavelength of 365 nm.

[0017] (Configuration 10) A method for manufacturing a transfer mask using the mask blank according to any one of configurations 1 to 9, comprising: forming a transfer pattern on the etching mask film; forming a transfer pattern on the thin film by wet etching using the etching mask film on which the transfer pattern has been formed as a mask; 1. A method for manufacturing a transfer mask, comprising:

[0018] (Configuration 11) A method for manufacturing a display device using a transfer mask manufactured by the method for manufacturing a transfer mask according to configuration 10, comprising: placing the transfer mask on a mask stage of an exposure tool; a step of irradiating the transfer mask with exposure light to transfer a transfer pattern onto a resist film provided on a substrate for a display device; A method for manufacturing a display device, comprising: [Effects of the Invention]

[0019] According to the present invention, it is possible to provide a mask blank, a method for manufacturing a transfer mask, and a method for manufacturing a display device that can suppress the phenomenon of peeling of an etching mask film when a cleaning process using a chemical solution is performed. [Brief explanation of the drawings]

[0020] [Figure 1] 1 is a cross-sectional view showing a main part of a mask blank in an embodiment of the present invention. [Figure 2] 1A to 1C are schematic diagrams illustrating a manufacturing process of a phase shift mask (transfer mask) according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0021] First, the background to the invention will be described. The present inventors have conducted extensive research into a configuration that can prevent the etching mask film from peeling off when a cleaning process using a chemical solution is performed on a mask blank having a structure in which a thin film for pattern formation (hereinafter, sometimes simply referred to as a "thin film") made of a metal silicide nitride-based material and an etching mask film made of a chromium-based material are stacked on a light-transmitting substrate.

[0022] The inventors of the present application noticed that peeling of an etching mask film is more likely to occur in the periphery of the etching mask film than in the center when viewed from above. Detailed observation of the surfaces of the etching mask films on multiple mask blanks revealed that there are cases where areas with significantly poor film quality (hereinafter referred to as "micro-pinholes") are locally present in the periphery of the etching mask film. Such micro-pinholes are not easy to detect using conventional defect inspection equipment. Next, multiple mask blanks in which micro-pinholes were found in the periphery of the etching mask film were subjected to multiple chemical cleaning processes. As a result, it was found that film peeling occurs with a relatively high probability in the areas where pinhole defects were found.

[0023] Meanwhile, the inventors of the present application investigated the reason why micro-pinholes are more likely to occur in the peripheral portion of the etching mask film. As a result, they found that the thickness of the peripheral portion of the etching mask film is thinner than other portions (such as the center), which causes localized areas where sputtered particles are not sufficiently deposited and grown, resulting in micro-pinholes. Liquids such as chemicals are more likely to seep into areas of the etching mask film where micro-pinholes exist. Furthermore, when the etching mask film is formed using an in-line sputtering device, micro-pinholes are more likely to occur in the peripheral portion.

[0024] Based on these results, the inventors of the present application hypothesized the following: When a cleaning process is performed on a mask blank using a chemical solution (such as sulfuric acid / hydrogen peroxide mixture, ammonia / hydrogen peroxide mixture, or ozone water), the chemical solution first seeps through the tiny pinholes in the etching mask film and reaches the interface between the etching mask film made of a chromium-based material and the thin film made of a metal silicide nitride-based material. The chemical solution then dissolves the surface of the thin film made of a metal silicide nitride-based material. This causes a loss of adhesion between the thin film and the etching mask film. The mechanical rigidity of the etching mask film in the area of ​​the tiny pinholes is low. During the cleaning process, the chemical solution flows over the surface of the etching mask film, causing a physical impact on the area of ​​the tiny pinholes. It was hypothesized that these actions cause film peeling in the area of ​​the tiny pinholes.

[0025] Based on these hypotheses, the present inventors conceived of a method for creating a thin film of a metal silicide nitride-based material that is less soluble in chemical solutions than conventional thin films. Increasing the ratio of nitrogen to silicon in the thin film improves chemical resistance. However, thin films of metal silicide nitride-based materials are designed to achieve desired optical properties because a transfer pattern is formed in the thin film when the transfer mask is manufactured. For this reason, the ratio of nitrogen to silicon in the thin film cannot be easily increased. The present inventors realized that a transfer pattern is generally not formed in the outer periphery of the thin film. Furthermore, they discovered that the chemical resistance of the outer periphery of a thin film containing metal, silicon, and nitrogen can be improved by making the ratio of nitrogen to silicon in the outer periphery greater than the ratio of nitrogen to silicon in the remaining portion. Furthermore, they found that by increasing the chemical resistance of the thin film, even if there are tiny pinholes on the periphery of the etching mask film and chemicals seep in through them, it is possible to prevent a decrease in adhesion between the thin film and the etching mask film, and to prevent peeling of the etching mask film in the area where the tiny pinholes are present. The present invention has been made as a result of the above-mentioned intensive investigations.

[0026] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. Note that the following embodiment is one form for realizing the present invention and does not limit the scope of the present invention. Note that in the drawings, the same or corresponding parts are given the same reference numerals, and their description may be simplified or omitted.

[0027] 1 is a cross-sectional view showing a main portion of a mask blank according to an embodiment of the present invention. As shown in the figure, a mask blank 10 includes a light-transmitting substrate 20, a pattern-forming thin film 30 provided on a main surface 21 of the light-transmitting substrate 20, and an etching mask film 40 provided on the pattern-forming thin film 30. Each element will be described below.

[0028] <Transparent substrate 20> The light-transmitting substrate 20 (or may be simply referred to as the substrate 20) is a rectangular plate-like body having two opposing main surfaces 21, 22, a side surface 23, and a chamfered surface (C-face) 24. The two opposing main surfaces 21, 22 are the upper and lower surfaces of this plate-like body, and are formed to face each other. At least one of the two opposing main surfaces 21, 22 is the main surface 21 on which a transfer pattern is to be formed (sometimes referred to as one main surface). The main surface 22 opposite the main surface 21 on which the transfer pattern is to be formed is sometimes referred to as the back surface (or the other main surface).

[0029] The light-transmitting substrate 20 is transparent to the exposure light. The light-transmitting substrate 20 has a transmittance of 85% or more, preferably 90% or more, to the exposure light, assuming no surface reflection loss. The light-transmitting substrate 20 is made of a material containing silicon and oxygen, and can be made of glass materials such as synthetic quartz glass, quartz glass, aluminosilicate glass, soda-lime glass, and low-thermal expansion glass (SiO2-TiO2 glass, etc.). When the light-transmitting substrate 20 is made of low-thermal expansion glass, it is possible to suppress positional changes in the phase shift film pattern caused by thermal deformation of the light-transmitting substrate 20. Furthermore, the light-transmitting substrate 20 for a phase shift mask blank used in a display device is generally a rectangular substrate, with the length of the short side of the light-transmitting substrate being 300 mm or more. The present invention provides a phase shift mask blank that can provide a phase shift mask that can stably transfer a fine phase shift film pattern, for example, less than 2.0 μm, formed on a light-transmitting substrate 20, even if the light-transmitting substrate 20 has a large short side length of 300 mm or more.

[0030] <Phase shift film (thin film for pattern formation) 30> A phase shift film (a thin film for pattern formation) 30 is provided on a main surface 21 of the light-transmitting substrate 20. The phase shift film 30 has an outer peripheral portion 32 (a region indicated by OT3 in FIG. 1 ) and a portion other than the outer peripheral portion (a central portion) 31 (a region indicated by IN3 in FIG. 1 ). From the viewpoint of adhesion between the thin film 30 and the etching mask film 40, it is preferable that the boundary between the outer peripheral portion 32 and the central portion 31 of the phase shift film 30 be closer to the center than the boundary between the outer peripheral portion 42 (a region indicated by OT4 in FIG. 1 ) and the central portion 41 (a region indicated by IN4 in FIG. 1 ) of an etching mask film 40 described below.

[0031] The phase shift film 30 contains metal, silicon, and nitrogen. The ratio C2(N) / C2(Si) of the nitrogen content to the silicon content in the outer peripheral portion 32 of the phase shift film 30 is greater than the ratio C1(N) / C1(Si) of the nitrogen content to the silicon content in the central portion 31 of the phase shift film 30. The outer peripheral portion 32 of the phase shift film 30 configured in this manner is highly resistant to chemicals used in cleaning processes, etc. This prevents dissolution of the surface of the outer peripheral portion 32 and a decrease in adhesion to the etching mask film 40, even if a micro-pinhole exists in the outer peripheral portion 42 of the etching mask film 40 and a chemical solution penetrates through the micro-pinhole and reaches the outer peripheral portion 32 of the phase shift film 30. Furthermore, peeling of the micro-pinhole and the etching mask film 40 around it can be prevented.

[0032] The ratio C2(N) / C2(Si) in the outer circumferential portion 32 of the phase shift film 30 is preferably 0.9 or more. By satisfying this condition, the resistance of the outer circumferential portion 32 of the phase shift film 30 to chemical solutions is further improved. The ratio C2(N) / C2(Si) in the outer circumferential portion 32 of the phase shift film 30 is more preferably 0.95 or more, and even more preferably 1.0 or more. On the other hand, the ratio C2(N) / C2(Si) in the outer circumferential portion 32 of the phase shift film 30 is preferably 1.5 or less, more preferably 1.4 or less, and even more preferably 1.3 or less.

[0033] The ratio C2(N) / {C2(Si)+C2(M)} of the nitrogen content to the total content of silicon and metal in the outer peripheral portion 32 of the phase shift film 30 is preferably 0.63 or more. By satisfying this condition, the resistance of the outer peripheral portion 32 of the phase shift film 30 to chemical solutions is further improved. The ratio C2(N) / {C2(Si)+C2(M)} in the outer peripheral portion 32 of the phase shift film 30 is more preferably 0.65 or more, and even more preferably 0.68 or more. Furthermore, the ratio C2(N) / {C2(Si)+C2(M)} in the outer peripheral portion 32 of the phase shift film 30 is preferably 1.2 or less, more preferably 1.15 or less, and even more preferably 1.0 or less.

[0034] The ratio C2(N) / {C2(Si)+C2(M)+C2(O)} of the nitrogen content to the total content of silicon, metal, and oxygen in the outer peripheral portion 32 of the phase shift film 30 is preferably 0.58 or greater. By satisfying this condition, the resistance of the outer peripheral portion 32 of the phase shift film 30 to chemical solutions is further improved. The ratio C2(N) / {C2(Si)+C2(M)+C2(O)} in the outer peripheral portion 32 of the phase shift film 30 is preferably 0.6 or greater, and more preferably 0.62 or greater. Furthermore, the ratio C2(N) / {C2(Si)+C2(M)+C2(O)} in the outer peripheral portion 32 of the phase shift film 30 is preferably 1.0 or less, more preferably 0.9 or less, and even more preferably 0.8 or less. Furthermore, the ratio [C2(N) / C2(Si)] / [C1(N) / C1(Si)] calculated by dividing the ratio C2(N) / C2(Si) of the nitrogen content to the silicon content in the outer peripheral portion 32 of the phase shift film 30 by the ratio C1(N) / C1(Si) of the nitrogen content to the silicon content in the central portion 31 of the phase shift film 30 is preferably 1.1 or more, and more preferably 1.15 or more.

[0035] The phase shift film 30 may have a smaller thickness in the outer peripheral portion 32 than in the central portion 31. In this case, the thickness of the central portion 31 may be set to the average thickness of the film in the region IN3 of the central portion 31. Furthermore, the region OT3 of the outer peripheral portion 32 may be set to a region having a smaller thickness than the average thickness of the central portion 31.

[0036] The phase shift film 30 may have a columnar structure at least partially in the thickness direction. The columnar structure here refers to a state in which the particles of the material constituting the phase shift film 30 have a columnar grain structure extending in the film thickness direction of the phase shift film 30 (the direction in which the particles are deposited). (The same applies to the etching mask film 40, described later.) By forming a columnar structure at least partially in the thickness direction of the phase shift film 30, the etching rate in the wet etching process for forming a transfer pattern can be increased. Thin films with a columnar structure tend to have reduced resistance to cleaning with chemical solutions. However, the outer peripheral portion 32 of the phase shift film 30 has a high ratio of nitrogen content to silicon content, thereby increasing its resistance to chemical solutions. Therefore, even if a chemical solution penetrates through tiny pinholes in the outer peripheral portion 41 of the etching mask film 40 and reaches the outer peripheral portion 32 of the phase shift film 30, dissolution of the surface of the outer peripheral portion 32 and a decrease in adhesion to the etching mask film 40 can be prevented.

[0037] The metal contained in phase shift film 30 is preferably a transition metal such as molybdenum (Mo), tantalum (Ta), tungsten (W), titanium (Ti), or zirconium (Zr), and preferably contains at least molybdenum. The nitrogen content in the phase shift film 30 is preferably greater than 10 atomic % and less than or equal to 50 atomic %, and more preferably greater than or equal to 15 atomic % and less than or equal to 45 atomic %. The total metal, silicon, and nitrogen content in the phase shift film 30 is preferably greater than or equal to 90 atomic %, and more preferably greater than or equal to 92 atomic %. The ratio of the metal content to the total metal and silicon content in the phase shift film 30 is preferably less than or equal to 0.5, more preferably less than or equal to 0.45, and even more preferably less than or equal to 0.35.

[0038] The phase shift film 30 may contain oxygen. The content of oxygen in the phase shift film 30 is preferably 10 atomic % or less, and more preferably 8 atomic % or less. The phase shift film 30 has a function of adjusting the transmittance and phase difference of the exposure light. Preferably, the phase shift film 30 also has a function of adjusting the reflectance of the light incident from the light-transmitting substrate 20 side (hereinafter, sometimes referred to as back surface reflectance). The phase shift film 30 can be formed by sputtering.

[0039] The transmittance of the exposure light in the portion (central portion) 31 of the phase shift film 30 other than the peripheral portion satisfies the value required for the phase shift film 30. The transmittance of the central portion 31 of the phase shift film 30 is preferably 3% or more, more preferably 10% or more, for light of a specific wavelength contained in the exposure light (hereinafter referred to as the representative wavelength, for example, light with a wavelength of 365 nm). The transmittance is preferably 70% or less, more preferably 65% ​​or less, for the representative wavelength. That is, when the exposure light is a composite light containing light of a wavelength range of 313 nm to 436 nm, the central portion 31 of the phase shift film 30 has the above-mentioned transmittance for light of the representative wavelength contained in that wavelength range. For example, when the exposure light is a composite light containing i-line, h-line, and g-line, the portion of the phase shift film 30 other than the peripheral portion has the above-mentioned transmittance for any of the i-line, h-line, and g-line. The transmittance can be measured using a phase shift amount measuring device or the like.

[0040] The phase difference of the central portion 31 of the phase shift film 30 relative to the exposure light satisfies the required value for the phase shift film 30. The phase difference of the central portion 31 of the phase shift film 30 relative to the light with a representative wavelength contained in the exposure light is preferably 150 degrees or more and 210 degrees or less, more preferably 160 degrees or more and 200 degrees or less, and even more preferably 170 degrees or more and 190 degrees or less. This property allows the phase of the light with a representative wavelength contained in the exposure light to be changed within a predetermined phase difference range. Therefore, a predetermined phase difference is generated between the light with a representative wavelength that has passed through the central portion 31 of the phase shift film 30 and the light with a representative wavelength that has passed only through the light-transmitting substrate 20. In other words, when the exposure light is composite light containing light with a wavelength range of 313 nm or more and 436 nm or less, the central portion 31 of the phase shift film 30 has the above-described phase difference relative to the light with a representative wavelength contained in that wavelength range. For example, when the exposure light is a composite light including i-line, h-line, and g-line, the central portion 31 of the phase shift film 30 has the above-mentioned phase difference with respect to any one of the i-line, h-line, and g-line. The phase difference can be measured using a phase shift amount measuring device or the like.

[0041] <Etching mask film 40> An etching mask film 40 is provided on the surface of the phase shift film (thin film for pattern formation) 30. The etching mask film 40 is formed of a material containing chromium. Examples of materials for forming the etching mask film 40 include chromium (Cr) and materials containing chromium (Cr) and at least one of oxygen (O), nitrogen (N), and carbon (C). Alternatively, examples of materials for forming the etching mask film 40 include materials containing chromium (Cr) and at least one of oxygen (O), nitrogen (N), and carbon (C) and further containing fluorine (F). Examples of materials for the etching mask film 40 include Cr, CrO, CrN, CrF, CrCO, CrCN, CrON, CrCON, and CrCONF. The etching mask film 40 has etching resistance to the etching solution used to etch the phase shift film 30.

[0042] The etching mask film 40 has an outer peripheral portion 42 (a region indicated by OT4 in FIG. 1) and a portion (a central portion) 41 other than the outer peripheral portion (a region indicated by IN4 in FIG. 1). The film thickness of the outer peripheral portion 42 of the etching mask film 40 is smaller than the film thickness of the portion (central portion) 41 other than the outer peripheral portion of the etching mask film 40. In this case, the film thickness of the central portion 41 can be set to the average value of the film thickness within the region IN4 of the central portion 41.

[0043] Alternatively, the peripheral portion 42 of the etching mask film 40 (the region indicated by OT4 in FIG. 1 ) may be a region where the ratio of the film thickness at the peripheral portion 42 of the etching mask film 40 to the film thickness at the central portion 41 of the etching mask film 40 is 0.7 or less. In this case, the boundary between the peripheral portion 32 and the central portion 31 of the phase shift film 30 can be set at the same position as or closer to the center than the boundary from the outer edge of the phase shift film 30 in a plan view where the ratio of the film thickness at the peripheral portion 42 of the etching mask film 40 is 0.7. The region where the ratio of the film thickness at the peripheral portion 42 of the etching mask film 40 to the film thickness at the central portion 41 of the etching mask film 40 is 0.7 or less tends to be prone to the occurrence of micro-pinholes. This configuration allows the peripheral portion 32, which has a high ratio of nitrogen content to silicon content, to be formed so as to encompass at least the region of the phase shift film 30 directly below the peripheral portion 42 of the etching mask film 40. This prevents the surface of the outer periphery 32 from dissolving and reducing adhesion to the etching mask film 40, even if a tiny pinhole exists in the outer periphery 42 of the etching mask film 40 and the chemical solution seeps in through the tiny pinhole and reaches the outer periphery 32 of the phase shift film 30.

[0044] The outer peripheral portion 42 of the etching mask film 40 is preferably formed to cover the entire outer peripheral edge of the outer peripheral portion 32 of the phase shift film 30. This prevents the chemical solution from coming into direct contact with the surface of the phase shift film 30 during the cleaning process. The etching mask film 40 may have a function of blocking the transmission of exposure light, and in addition to or instead of this, may have a function of reducing the film surface reflectance. The etching mask film 40 can be formed by a sputtering method.

[0045] The etching mask film 40 can be configured to have a columnar structure in at least a portion of its thickness. By forming a columnar structure in at least a portion of the thickness of the etching mask film 40, the etching rate in the wet etching process for forming a transfer pattern can be increased. On the other hand, a thin film having a columnar structure, such as the outer peripheral portion 42 of the etching mask film 40, is prone to the occurrence of micro-pinholes. By configuring the outer peripheral portion 32 of the phase shift film 30 as described above, peeling of the outer peripheral portion 41 of the etching mask film 40 can be prevented when cleaning with a chemical solution.

[0046] When the etching mask film 40 has the function of blocking the transmission of exposure light, the optical density with respect to exposure light in the portion where the phase shift film 30 and the etching mask film 40 are laminated is preferably 3 or more, more preferably 3.5 or more, and even more preferably 4 or more. The optical density can be measured using a spectrophotometer or an OD meter.

[0047] <Mask Blank Manufacturing Method> Next, a method for manufacturing the mask blank 10 of this embodiment will be described. The phase shift mask blank 10 is manufactured by performing the following phase shift film formation process and etching mask film formation process. An in-line sputtering system is preferably used to form the phase shift film 30 and etching mask film 40. The phase shift film 30 and etching mask film 40 formed by sputtering using an in-line sputtering system are likely to have columnar structures formed therein. Each process will be described in detail below.

[0048] 1. Phase shift film formation process A light-transmitting substrate 20 is prepared, and a phase shift film (a thin film for forming a pattern) 30 is formed on the light-transmitting substrate 20 by sputtering. The phase shift film 30 is formed using a sputtering target containing a transition metal and silicon, which are the main components of the material constituting the phase shift film 30, in a sputtering gas atmosphere consisting of a mixed gas of an inert gas containing at least one selected from the group consisting of helium gas, neon gas, argon gas, krypton gas, and xenon gas, and an active gas containing at least one selected from the group consisting of nitric oxide gas and nitrogen dioxide gas.

[0049] During the deposition of this phase shift film 30, the flow rate ratio of each gas in the sputtering gas is adjusted so that a portion (central portion) 31 of the phase shift film 30 other than the peripheral portion has desired optical properties (transmittance, phase difference, etc.). At the same time, the ratio C2(N) / C2(Si) of the nitrogen content to the silicon content in the peripheral portion 32 of the phase shift film 30 is adjusted to be larger than the ratio C1(N) / C1(Si) of the nitrogen content to the silicon content in the central portion 31. For example, a supply port may be provided so that the sputtering gas and nitrogen-based gas are actively supplied to a position through which the outer periphery of the light-transmitting substrate 20 passes when the light-transmitting substrate 20 is placed in the sputtering apparatus.

[0050] 3. Etching mask film formation process After performing a surface treatment to adjust the state of surface oxidation on the surface of the phase shift film 30, an etching mask film 40 is formed by sputtering on the phase shift film 30. At this time, the thickness of an outer peripheral portion 42 of the etching mask film 40 is smaller than the thickness of a portion (central portion) 41 other than the outer peripheral portion.

[0051] The etching mask film 40 is formed using a sputtering target containing chromium or a chromium compound (e.g., chromium oxide, chromium nitride, chromium carbide, chromium oxynitride, chromium oxynitride carbide, etc.) in a sputtering gas atmosphere consisting of at least one inert gas selected from the group consisting of helium gas, neon gas, argon gas, krypton gas, and xenon gas, or a mixed gas of an inert gas selected from the group consisting of helium gas, neon gas, argon gas, krypton gas, and xenon gas and an activated gas selected from the group consisting of oxygen gas, nitrogen gas, nitric oxide gas, nitrogen dioxide gas, carbon dioxide gas, a hydrocarbon gas, and a fluorine gas. Examples of hydrocarbon gases include methane gas, butane gas, propane gas, and styrene gas. In this way, the mask blank 10 is obtained.

[0052] <Phase shift mask (transfer mask) and its manufacturing method> FIG. 2 is a schematic diagram showing the manufacturing process of a phase shift mask (transfer mask) according to an embodiment of the present invention. The method for manufacturing a phase shift mask shown in Fig. 2 is a method for manufacturing a phase shift mask using the mask blank 10 shown in Fig. 1. As shown in Fig. 2(e), phase shift mask 100 is characterized in that phase shift film pattern 30a, which is a transfer pattern, is formed in phase shift film 30 of mask blank 10, and second etching mask film pattern 40b, which functions as a light-shielding pattern, is formed in etching mask film 40. This phase shift mask 100 has the same technical features as mask blank 10. Matters related to light-transmitting substrate 20, central portion 31 and peripheral portion 32 of phase shift film 30, and central portion 41 and peripheral portion 42 of etching mask film 40 in phase shift mask 100 are the same as those in mask blank 10.

[0053] The method for manufacturing a phase shift mask includes the steps of forming a resist film on a mask blank 10, drawing and developing a desired pattern on the resist film to form a resist film pattern 50 (first resist film pattern formation step), patterning an etching mask film 40 by wet etching using the resist film pattern 50 as a mask to form an etching mask film pattern 40a (first etching mask film pattern formation step), and wet etching a phase shift film 30 using the etching mask film pattern 40a as a mask to form a phase shift film pattern 30a on a light-transmitting substrate 20 (phase shift film pattern formation step).The method further includes a second resist film pattern formation step and a second etching mask film pattern formation step. Note that cleaning treatments using chemicals (such as sulfuric acid / hydrogen peroxide, ammonia / hydrogen peroxide, or ozone water), DIW (deionized water), or the like are performed between each step as appropriate. Each step will be explained below.

[0054] 1. First resist film pattern formation process In the first resist film pattern formation step, a resist film is first formed on the etching mask film 40 of the phase shift mask blank 10. There are no particular limitations on the resist film material used. For example, any material that is sensitive to laser light having a wavelength selected from the wavelength range of 350 nm to 436 nm may be used. The resist film may be either positive or negative. Thereafter, a desired pattern is drawn on the resist film using a laser beam having a wavelength selected from the wavelength range of 350 nm to 436 nm. The pattern drawn on the resist film is the pattern to be formed on the phase shift film 30. Examples of the pattern drawn on the resist film include a line and space pattern and a hole pattern. Thereafter, the resist film is developed with a predetermined developer to form a first resist film pattern 50 on the etching mask film 40, as shown in Fig. 2(a). After the development of the resist film is completed, a cleaning process using DIW or the like is performed.

[0055] 2. First etching mask film pattern formation process In the first etching mask film pattern forming step, first, the etching mask film 40 is etched using the first resist film pattern 50 as a mask to form a first etching mask film pattern 40a. The etching mask film 40 is made of a chromium-based material containing chromium (Cr). The etching solution used to etch the etching mask film 40 is not particularly limited as long as it can selectively etch the etching mask film 40. Specifically, an etching solution containing ceric ammonium nitrate and perchloric acid can be used. After etching of the etching mask film 40 is completed, a cleaning process is performed using a chemical solution, DIW, or the like.

[0056] 2(b), the first resist film pattern 50 is stripped from the etching mask film 40 using a resist stripper, and then a cleaning process is performed using a chemical solution or DIW. In some cases, the next phase shift film pattern forming process may be performed without stripping the first resist film pattern 50.

[0057] 3. Phase shift film pattern formation process In the first phase shift film pattern formation step, the phase shift film 30 is etched using the first etching mask film pattern 40a as a mask to form a phase shift film pattern 30a as shown in FIG. 2(c). Examples of the phase shift film pattern 30a include a line-and-space pattern and a hole pattern. The etchant used to etch the phase shift film 30 is not particularly limited as long as it can selectively etch the phase shift film 30. Examples of suitable etchants include an etchant containing ammonium fluoride, phosphoric acid, and hydrogen peroxide, and an etchant containing ammonium hydrogen fluoride and hydrogen chloride. After etching of the phase shift film 30 is completed, a cleaning process is performed using a chemical solution, DIW, or the like.

[0058] 4. Second resist film pattern formation process In the second resist film pattern forming step, first, a resist film is formed to cover the first etching mask film pattern 40a. The resist film material to be used is not particularly limited, as with the resist film material in the first resist film pattern forming step. Thereafter, a desired pattern is drawn on the resist film using a laser beam having a wavelength selected from the wavelength range of 350 nm to 436 nm. The pattern drawn on the resist film is a light-shielding pattern that shields the outer peripheral region of the region where the pattern is formed on the phase shift film 30, and a light-shielding pattern that shields the central portion of the phase shift film pattern 30a. Note that, depending on the transmittance of the phase shift film 30 to the exposure light, the pattern drawn on the resist film may not have a light-shielding pattern that shields the central portion of the phase shift film pattern 30a. Thereafter, the resist film is developed with a predetermined developer to form a second resist film pattern 60 on the first etching mask film pattern 40a, as shown in Fig. 2(d). After the development of the resist film is completed, a cleaning process using DIW or the like is performed.

[0059] 5. Second etching mask film pattern formation process In the second etching mask film pattern forming step, the first etching mask film pattern 40a is etched using the second resist film pattern 60 as a mask to form a second etching mask film pattern 40b as shown in FIG. 2(e). The first etching mask film pattern 40a is made of a chromium-based material containing chromium (Cr). The etching solution used to etch the first etching mask film pattern 40a is not particularly limited as long as it can selectively etch the first etching mask film pattern 40a. For example, an etching solution containing ceric ammonium nitrate and perchloric acid can be used. Thereafter, a resist stripper is used to strip the second resist film pattern 60. After etching of the etching mask film 40 is completed, a cleaning process is performed using a chemical solution, DIW, or the like. In this way, the phase shift mask 100 is obtained.

[0060] In the above explanation, the etching mask film 40 has the function of blocking the transmission of exposure light. However, in the case where the etching mask film 40 simply functions as a hard mask when etching the phase shift film 30, the second resist film pattern forming process and the second etching mask film pattern forming process are not performed, and after the phase shift film pattern forming process, the first etching mask film pattern is peeled off to produce the phase shift mask 100.

[0061] This phase shift mask manufacturing method uses the mask blank of embodiment 1. Therefore, even if minute pinholes exist in outer periphery 42 of etching mask film 40, peeling of etching mask film 40 from outer periphery 42 where the minute pinholes exist is suppressed when a cleaning process with a chemical solution is performed between each manufacturing step of the phase shift mask. Therefore, it is possible to manufacture a phase shift mask in which defects due to film peeling in outer periphery 42 are suppressed and defects due to film peeled from outer periphery 42 adhering to the phase shift film pattern are also suppressed.

[0062] <Display Device Manufacturing Method> The display device is manufactured by carrying out the above-mentioned step of using the transfer mask (mask placement step) and the step of exposing and transferring a transfer pattern onto a resist film on the display device (pattern transfer step). Each step will be described in detail below.

[0063] 1. Placement process In the placing step, the transfer mask is placed on a mask stage of an exposure tool. Here, the transfer mask may be either a phase shift mask (transfer mask) 100 manufactured using the mask blank 10, or a new transfer mask manufactured by the new transfer mask manufacturing method described above. The transfer mask is positioned so as to face the resist film formed on the display device substrate via the projection optical system of the exposure tool.

[0064] 2.Pattern transfer process In the pattern transfer process, a transfer mask is irradiated with exposure light to transfer a phase shift film pattern to a resist film formed on a display device substrate. The exposure light is composite light containing light of multiple wavelengths selected from the wavelength range of 365 nm to 436 nm, or monochromatic light selected by cutting a certain wavelength range from the wavelength range of 365 nm to 436 nm using a filter or the like. For example, the exposure light is composite light containing i-line, h-line, and g-line, or monochromatic i-line light. Using composite light as the exposure light allows the exposure light intensity to be increased, thereby increasing throughput and reducing the manufacturing cost of the display device.

[0065] According to this method for manufacturing a display device, a phase shift mask is used in which defects in the outer periphery 42 of the etching mask film 40 and in the phase shift film pattern are suppressed, so that a display device with low defects and high resolution and high definition can be manufactured. [Example]

[0066] Example 1 A. Mask blanks and their manufacturing methods To manufacture the mask blank 10 of Example 1, first, a synthetic quartz glass substrate having a 1214 size (1220 mm×1400 mm) was prepared as the light-transmitting substrate 20 .

[0067] Thereafter, the synthetic quartz glass substrate was placed on a tray (not shown) with the main surface facing downward, and was then carried into the chamber of an in-line sputtering device. To form a phase shift film 30 on the main surface 21 of the light-transmitting substrate 20, a first chamber was first evacuated to a predetermined vacuum level, and a mixed gas of argon (Ar), oxygen (O2), and nitrogen (N2) gases was introduced. A first sputtering target containing molybdenum and silicon (molybdenum:silicon=1:4) was used for reactive sputtering to form a phase shift film 30 of molybdenum silicide oxynitride containing molybdenum, silicon, oxygen, and nitrogen on the main surface of the light-transmitting substrate 20. The nitrogen flow rate in the deposition chamber and the locations of the gas inlets and outlets were adjusted so that a sufficient amount of nitrogen gas was supplied to the central portion 31 of the phase shift film 30 while a larger amount was supplied to the peripheral portion 32.

[0068] The thickness of the central portion 31 of the phase shift film 30 was 110 nm. The thickness of the outer peripheral portion 32 was smaller than that of the central portion 31, and the thickness had a distribution that decreased toward the outer peripheral edge.

[0069] Next, the transparent substrate 20 with the phase shift film 30 was loaded into a second chamber, and a mixed gas of argon (Ar) gas and nitrogen (N2) gas was introduced into the second chamber with the chamber evacuated to a predetermined degree. Then, a chromium nitride (CrN) containing chromium and nitrogen was formed on the phase shift film 30 by reactive sputtering using a second sputtering target made of chromium (thickness: 15 nm). Next, a mixed gas of argon (Ar) gas and methane (CH4) gas was introduced into a third chamber with the chamber evacuated to a predetermined degree. Then, a chromium carbide (CrC) containing chromium and carbon was formed on the CrN by reactive sputtering using a third sputtering target made of chromium (thickness: 60 nm). Finally, with the fourth chamber evacuated to a predetermined vacuum, a mixture of argon (Ar) gas, methane (CH4) gas, nitrogen (N2) gas, and oxygen (O2) gas (Ar+CH4) was introduced, and a chromium carbon-oxynitride (CrCON) containing chromium, carbon, oxygen, and nitrogen was formed on the CrC by reactive sputtering using a fourth sputtering target made of chromium (thickness: 30 nm). In this way, an etching mask film 40 having a stacked structure of a CrN layer, a CrC layer, and a CrCON layer was formed on the phase shift film 30.

[0070] The thickness of the central portion 41 of the etching mask film 40 was 105 nm. The outer periphery 42 was thinner than the central portion 41, and the thickness had a thickness distribution that decreased toward the outer periphery. The boundary between the outer periphery 32 and the central portion 31 of the phase shift film 30 was located closer to the center than the boundary between the outer periphery 42 and the central portion 41 of the etching mask film 40. In this way, a mask blank 10 was obtained in which the phase shift film 30 and the etching mask film 40 were formed on the light-transmitting substrate 20.

[0071] The transmittance and phase difference of the central portion 31 of the phase shift film 30 of the obtained mask blank 10 were measured using an MPM-100 manufactured by Lasertec Corporation. To measure the transmittance and phase difference of the phase shift film 30, a phase shift film-coated substrate (dummy substrate) was used, which was prepared by setting the phase shift film 30 on the main surface of a synthetic quartz glass substrate and prepared on the same tray. The transmittance and phase difference of the phase shift film 30 were measured by removing the phase shift film-coated substrate (dummy substrate) from the chamber before forming the etching mask film 40. The results were a transmittance of 5.2% (wavelength: 365 nm) and a phase difference of 176 degrees (wavelength: 365 nm).

[0072] A phase shift film and an etching mask film were formed on another light-transmitting substrate under the above-mentioned conditions. Then, the outer and central portions of the phase shift film were subjected to depthwise composition analysis using X-ray photoelectron spectroscopy (XPS). The results of the depthwise composition analysis of the mask blank 10 using XPS revealed that the nitrogen content in the outer peripheral portion 32 of the phase shift film 30 was greater than the nitrogen content in the central portion (portion other than the outer peripheral portion) 31. Furthermore, in both the outer peripheral portion 32 and the central portion 31, the oxygen content was found to be 10 atomic % or less, and the total content of metal, silicon, and nitrogen was found to be 90 atomic % or more.

[0073] The average values ​​of each composition in the central portion 31 of the phase shift film 30 were calculated, and the molybdenum content C1 (Mo) was 16.4 atomic %, the silicon content C1 (Si) was 41.4 atomic %, the nitrogen content C1 (N) was 35.6 atomic %, the oxygen content C1 (O) was 5.6 atomic %, and the carbon content C1 (C) was 1.0 atomic %.

[0074] On the other hand, when the average values ​​of each composition in the outer peripheral portion 32 of the phase shift film 30 were calculated, the molybdenum content C2 (Mo) was 15.2 atomic %, the silicon content C2 (Si) was 39.7 atomic %, the nitrogen content C2 (N) was 39.9 atomic %, the oxygen content C2 (O) was 4.4 atomic %, and the carbon content C2 (C) was 0.8 atomic %.

[0075] From these results, it was found that the ratio C1(N) / C1(Si) in the central portion (portion other than the outer periphery) 31 was 0.860, which was less than 0.9. The ratio C1(N) / {C1(Si)+C1(Mo)} in the central portion (portion other than the outer periphery) 31 was 0.616, which was less than 0.63. The ratio C1(N) / {C1(Si)+C1(Mo)+C1(O)} in the central portion (portion other than the outer periphery) 31 was 0.562, which was less than 0.58.

[0076] In contrast, the ratio C2(N) / C2(Si) in the outer peripheral portion 32 was 1.01, which was found to be greater than 1.0. The ratio C2(N) / {C2(Si)+C2(Mo)} in the outer peripheral portion 32 was 0.727, which was found to be greater than 0.68. The ratio C2(N) / {C2(Si)+C2(Mo)+C2(O)} in the outer peripheral portion 32 was 0.673, which was found to be greater than 0.62. For each of the above ratios, the outer peripheral portion 32 was higher than the central portion 31. Furthermore, the ratio [C2(N) / C2(Si)] / [C1(N) / C1(Si)] calculated by dividing the ratio C2(N) / C2(Si) of the nitrogen content to the silicon content in the outer peripheral portion 32 of the phase shift film 30 by the ratio C1(N) / C1(Si) of the nitrogen content to the silicon content in the central portion 31 of the phase shift film 30 was 1.17. It was also found that in both the outer peripheral portion 32 and the central portion 31 of the phase shift film 30, the oxygen content was 10 atomic % or less, and the total content of metal, silicon, and nitrogen was 90 atomic % or more.

[0077] Meanwhile, cross-sectional SEM (Scanning Electron Microscope) images of the phase shift film 30 and the etching mask film 40 of this other light-transmitting substrate were obtained. As a result, it was found that the phase shift film 30 had columnar structures extending in the film thickness direction both in the central portion 31 and the peripheral portion 32. It was also found that the etching mask film 40 also had columnar structures extending in the film thickness direction both in the central portion 41 and the peripheral portion 42.

[0078] B. Phase shift mask and method of manufacturing the same For the phase shift mask blank 10 manufactured as described above, a phase shift mask 100 was obtained on a light-transmitting substrate 20 using the procedure shown in Figure 2, in which a phase shift film pattern 30a and a light-shielding pattern consisting of a laminated structure of the phase shift film pattern 30a and an etching mask film pattern 40b were formed in the transfer pattern forming area. When a mask defect inspection was performed on the phase shift mask 100, no defects due to film peeling were detected in the outer periphery 42 of the etching mask film pattern 40b. Also, no defects due to the adhesion of peeled film were detected in the phase shift film pattern 30a.

[0079] C. Display Device Manufacturing Method Therefore, when the phase shift mask of Example 1 is set on the mask stage of an exposure tool and exposed and transferred onto a resist film on a display device, it can be said that a fine pattern can be transferred with high precision and few defects.

[0080] Comparative Example 1 To manufacture the phase shift mask blank of Comparative Example 1, a synthetic quartz glass substrate having a 1214 size (1220 mm×1400 mm) was prepared as a light-transmitting substrate in the same manner as in Example 1. A synthetic quartz glass substrate was loaded into the chamber of an in-line sputtering apparatus. In Comparative Example 1, unlike Example 1, a phase shift film was formed without adjusting the nitrogen flow rate conditions or the arrangement of the gas inlet and outlet ports so that a larger amount of nitrogen gas was supplied to the outer periphery 32 within the chamber. The same sputtering target materials as in Example 1 were used for the first, second, third, and fourth sputtering targets. Then, an etching mask film was formed by the same method as in Example 1. As in Example 1, the outer periphery of the etching mask film had a smaller thickness than the central portion, and the thickness had a film thickness distribution in which the thickness decreased toward the outer periphery. In this way, a phase shift mask blank was obtained in which a phase shift film and an etching mask film were formed on a light-transmitting substrate.

[0081] The transmittance and phase difference of the phase shift film of the obtained phase shift mask blank (the surface of the phase shift film was washed with pure water) were measured using an MPM-100 manufactured by Lasertec Corporation. To measure the transmittance and phase difference of the phase shift film, a phase shift film-coated substrate (dummy substrate) was used, which was prepared by setting it on the same tray and had a phase shift film 30 formed on the main surface of a synthetic quartz glass substrate. The transmittance and phase difference of the phase shift film were measured by removing the phase shift film-coated substrate (dummy substrate) from the chamber before forming the etching mask film. The results were a transmittance of 5.2% (wavelength: 365 nm) and a phase difference of 176 degrees (wavelength: 365 nm).

[0082] Furthermore, a phase shift film and an etching mask film were formed on another light-transmitting substrate under the same conditions as Comparative Example 1. Then, composition analysis was performed in the depth direction on the outer periphery and central portion of the phase shift film by X-ray photoelectron spectroscopy (XPS). The composition analysis result for the central portion of the phase shift film was equivalent to that of Example 1.

[0083] On the other hand, when the average values ​​of each composition in the outer periphery of the phase shift film of Comparative Example 1 were calculated, the molybdenum content C2(Mo) was 20.1 atomic %, the silicon content C2(Si) was 49.5 atomic %, the nitrogen content C2(N) was 27.6 atomic %, the oxygen content C2(O) was 1.3 atomic %, the carbon content C2(C) was 1.5 atomic %, and the chromium content C2(Cr) was 0.2 atomic %.

[0084] From these results, it was found that the ratio C2(N) / C2(Si) in the outer periphery was 0.558, which was less than 0.9. The ratio C2(N) / {C2(Si) + C2(Mo)} in the outer periphery was 0.397, which was less than 0.63. The ratio C2(N) / {C2(Si) + C2(Mo) + C2(O)} in the outer periphery was 0.388, which was less than 0.58. For each of the above ratios, the outer periphery was higher than the central portion. Furthermore, the ratio [C2(N) / C2(Si)] / [C1(N) / C1(Si)] calculated by dividing the ratio C2(N) / C2(Si) of the nitrogen content to the silicon content in the outer peripheral part of the phase shift film by the ratio C1(N) / C1(Si) of the nitrogen content to the silicon content in the central part of the phase shift film was 0.65, which was less than 1.1.

[0085] Meanwhile, cross-sectional SEM (Scanning Electron Microscope) images of the phase shift film and etching mask film of another light-transmitting substrate of Comparative Example 1 were obtained. As a result, it was found that the phase shift film had columnar structures extending in the film thickness direction both in the central portion and the peripheral portion. It was also found that the etching mask film had columnar structures extending in the film thickness direction both in the central portion and the peripheral portion.

[0086] B. Phase shift mask and method of manufacturing the same A phase shift mask was produced in the same manner as in Example 1 using the phase shift mask blank produced as described above. When the phase shift mask of Comparative Example 1 was subjected to a mask defect inspection, defects due to film peeling were detected in part of the outer periphery of the etching mask film pattern. Also, defects presumably due to the adhesion of the peeled film were detected in the phase shift film pattern.

[0087] C. Display Device Manufacturing Method Therefore, when the phase shift mask of Comparative Example 1 is set on the mask stage of an exposure tool and exposed and transferred onto a resist film on a display device, it is difficult to transfer a fine pattern with high precision and few defects.

[0088] As described above, according to the present invention, it is possible to provide a mask blank, a method for manufacturing a transfer mask, and a method for manufacturing a display device that can suppress the phenomenon of peeling of an etching mask film when a cleaning process using a chemical solution is performed.

[0089] In the above embodiment, the case where molybdenum is used as the transition metal is described, but the same effect as above can be obtained when other transition metals are used. Furthermore, in the above-described embodiments, examples of phase shift mask blanks and phase shift masks for display device manufacturing have been described, but the present invention is not limited to these. The phase shift mask blanks and phase shift masks of the present invention can also be used for semiconductor device manufacturing, MEMS manufacturing, printed circuit board manufacturing, etc. Furthermore, the application of the present invention is not limited to phase shift mask blanks and phase shift masks, but can also be applied to mask blanks and transfer masks having a thin film containing metal, silicon, and nitrogen that functions as a transmittance adjusting film.

[0090] In the above-described embodiment, the size of the light-transmitting substrate is 8092 size (800 mm × 920 mm × 10 mm), but this is not limited to this. In the case of a phase shift mask blank for manufacturing a display device, a large-sized light-transmitting substrate is used, and the size of the light-transmitting substrate is 300 mm or more on one side. The size of the light-transmitting substrate used in a phase shift mask blank for manufacturing a display device is, for example, 330 mm × 450 mm or more and 2280 mm × 3130 mm or less. Furthermore, in the case of phase shift mask blanks for semiconductor device manufacturing, MEMS manufacturing, and printed circuit boards, small-sized light-transmitting substrates are used, and the size of the light-transmitting substrate has a side length of 9 inches or less. The size of the light-transmitting substrate used in phase shift mask blanks for the above applications is, for example, 63.1 mm × 63.1 mm or more and 228.6 mm × 228.6 mm or less. Typically, 6025 size (152 mm × 152 mm) or 5009 size (126.6 mm × 126.6 mm) is used for semiconductor device manufacturing and MEMS manufacturing, while 7012 size (177.4 mm × 177.4 mm) or 9012 size (228.6 mm × 228.6 mm) is used for printed circuit boards. [Explanation of symbols]

[0091] 10... mask blank, 20... light-transmitting substrate, 21...first main surface (main surface), 22...second main surface (main surface), 23...side surface, 24... chamfered surface (C surface), 30... phase shift film (thin film for pattern formation), 31...central portion (portion other than the outer periphery), 32...outer periphery, 30a...phase shift film pattern (thin film having a transfer pattern), 40...etching mask film, 41...central portion (portion other than the outer periphery), 42...outer periphery, 40a...first etching mask film pattern, 40b...second etching mask film pattern, 50...first resist film pattern, 60... second resist film pattern, 100... phase shift mask (transfer mask),

Claims

1. A mask blank in which a pattern-forming thin film and an etching mask film are laminated in this order on a main surface of a light-transmitting substrate, the thin film contains a metal, silicon, and nitrogen; the etching mask film has etching resistance to an etching solution that etches the thin film, a ratio of a film thickness of the outer peripheral portion of the etching mask film to a film thickness of a portion other than the outer peripheral portion of the etching mask film is 0.7 or less; a ratio of the nitrogen content to the silicon content in the outer peripheral portion of the thin film is greater than a ratio of the nitrogen content to the silicon content in a portion of the thin film other than the outer peripheral portion; The thickness of the thin film at the outer periphery is smaller than the thickness of the thin film at any other portion than the outer periphery. A mask blank characterized by:

2. 2. The mask blank according to claim 1, wherein a ratio calculated by dividing the ratio of the nitrogen content to the silicon content in the outer peripheral portion of the thin film by the ratio of the nitrogen content to the silicon content in portions of the thin film other than the outer peripheral portion is 1.1 or more.

3. 3. The mask blank according to claim 1, wherein the oxygen content of the thin film is 10 atomic % or less.

4. 4. The mask blank according to claim 1, wherein the total content of metal, silicon, and nitrogen in the thin film is 90 atomic % or more.

5. 5. The mask blank according to claim 1, wherein the thin film contains at least molybdenum.

6. 6. The mask blank according to claim 1, wherein the etching mask film has a columnar structure in at least a portion in the thickness direction.

7. 7. The mask blank according to claim 1, wherein the thin film has a columnar structure in at least a portion in the thickness direction.

8. the thin film is a phase shift film, 8. The mask blank according to claim 1, wherein a portion of the phase shift film other than the outer peripheral portion has a transmittance of 3% or more for light having a wavelength of 365 nm and a phase difference of 150 degrees or more and 210 degrees or less for light having a wavelength of 365 nm.

9. A method for manufacturing a transfer mask using the mask blank according to any one of claims 1 to 8, comprising the steps of: forming a transfer pattern on the etching mask film; forming a transfer pattern on the thin film by wet etching using the etching mask film on which the transfer pattern has been formed as a mask; 1. A method for manufacturing a transfer mask, comprising:

10. A method for manufacturing a display device using a transfer mask manufactured by the method for manufacturing a transfer mask according to claim 9, comprising the steps of: placing the transfer mask on a mask stage of an exposure tool; a step of irradiating the transfer mask with exposure light to transfer a transfer pattern onto a resist film provided on a substrate for a display device; A method for manufacturing a display device, comprising:

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