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

Abstract

To provide a mask blank that can suppress deterioration of the shape of a main surface on a translucent substrate after peeling a thin film for pattern formation or a thin film having a transfer pattern, and can contribute to improvement of production yield in recycling the mask blank.SOLUTION: A mask blank comprises a translucent substrate, and a thin film for pattern formation provided on a main surface of the translucent substrate, where the thin film contains metal, silicon and nitrogen, the thickness in the periphery of the thin film is thinner than the thickness of a portion of the thin film other than the periphery, a ratio of the content of nitrogen to the content of silicon in the periphery of the thin film is smaller than a ratio of the content of nitrogen to the content of silicon in a portion other than the 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 Art

[0002] In recent years, in display devices such as FPDs (Flat Panel Displays) typified by LCDs (Liquid Crystal Displays), with the trend towards larger screens and wider viewing angles, high definition and high-speed display have been rapidly advancing. One of the elements required for this high definition and high-speed display is the fabrication of electronic circuit patterns such as fine and highly dimensionally accurate elements and wirings. Photolithography is often used for patterning this electronic circuit for display devices. Therefore, a phase shift mask for manufacturing a display device with a fine and highly accurate pattern is required.

[0003] For example, Patent Document 1 discloses a phase shift mask blank including a translucent substrate, a light semi-transmissive film formed on the main surface of the translucent substrate and composed of a metal silicide-based material, and an etching mask film formed on this light semi-transmissive film and composed of a chromium-based material, in which a composition gradient region P is formed at the interface between the light semi-transmissive film and the etching mask film, and in this composition gradient region P, the ratio of the component that slows down the wet etching rate of the light semi-transmissive film increases stepwise and / or continuously in the depth direction, and a phase shift mask manufactured using this phase shift mask blank.

[0004] These phase shift masks may become unusable due to dirt or scratches caused by repeated use. They may also become unnecessary due to specification changes. On the other hand, in the process of manufacturing mask blanks, a certain proportion of mask blanks that do not meet the product specifications are generated. Furthermore, even for phase shift masks fabricated from mask blanks that meet the product specifications, there may be cases where they do not meet the phase shift mask specifications. Reusing these phase shift masks and mask blanks to manufacture (recycle) mask blanks is more effective from the perspectives of reducing manufacturing costs and resource utilization than discarding them. Also, for large-sized mask blanks and phase shift masks, large and expensive light-transmissive substrates (glass substrates) are used. If such light-transmissive substrates can be reused, particularly significant effects can be obtained.

[0005] For these reasons, attempts have been made to recycle used phase shift masks and to manufacture (recycle) new mask blanks using mask blanks and phase shift masks that do not meet the product specifications. For example, Patent Document 2 discloses a method of peeling a thin film on a glass substrate for mask blanks, which is mainly formed of a thin film containing metal, silicon, and nitrogen on a glass substrate, by bringing it into contact with an aqueous solution containing at least one fluorine compound selected from hydrofluoric acid, hexafluorosilicic acid, and ammonium hydrogen fluoride, and at least one oxidizing agent selected from hydrogen peroxide, nitric acid, and sulfuric acid, and containing 0.1 to 0.8 wt% of the fluorine compound for regeneration.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0007] As described above, when peeling a thin film containing metal, silicon, and nitrogen, a method of bringing an aqueous solution containing a fluorine compound and an oxidizing agent into contact therewith is suitable. However, a difference occurs in the peeling state of the thin film between the peripheral side and the central side of the thin film, and by bringing it into contact with the above aqueous solution until the peeling of the entire thin film is completed, a situation has occurred where the flatness of the substrate after thin film peeling deteriorates more than expected. For the substrate after thin film peeling, a predetermined polishing process or the like is performed so as to satisfy the flatness and surface roughness required for the substrate. However, in a substrate whose shape has deteriorated more than expected, there has been a situation where even if a predetermined polishing process is performed, the shape of the main surface cannot be sufficiently improved, or even if it can be improved, the desired plate thickness of the substrate cannot be ensured. In particular, this tendency was remarkable in large substrates for display devices.

[0008] The present invention has been made in view of the above-described problems, and can suppress deterioration of the shape of the main surface of a translucent substrate after peeling a thin film for pattern formation or a thin film having a transfer pattern, and can contribute to an improvement in the production yield during recycling. An object is to provide 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.

Means for Solving the Problems

[0009] As means for solving the above problems, the present invention has the following configuration.

[0010] (Configuration 1) A mask blank including a translucent substrate and a thin film for pattern formation provided on the main surface of the translucent substrate, The thin film contains metal, silicon, and nitrogen, The film thickness at the outer peripheral portion of the thin film is smaller than the film thickness at portions other than the outer peripheral portion of the thin film, The ratio of the nitrogen content to the silicon content in the outer peripheral portion of the thin film is smaller than the ratio of the nitrogen content to the silicon content in portions other than the outer peripheral portion of the thin film A mask blank characterized by the following.

[0011] (Configuration 2) The ratio of the film thickness of the thin film at the outer peripheral portion of the thin film to the film thickness of the thin film at a portion other than the outer peripheral portion of the thin film is 0.7 or less. The mask blank according to Configuration 1, characterized in that.

[0012] (Configuration 3) The ratio calculated by dividing the ratio of the nitrogen content to the silicon content at the outer peripheral portion of the thin film by the ratio of the nitrogen content to the silicon content at a portion other than the outer peripheral portion of the thin film is 0.84 or less. The mask blank according to Configuration 2, characterized in that.

[0013] (Configuration 4) The oxygen content of the thin film is 10 atomic% or less. The mask blank according to any one of Configurations 1 to 3, characterized in that.

[0014] (Configuration 5) The total content of metal, silicon, and nitrogen in the thin film is 90 atomic% or more. The mask blank according to any one of Configurations 1 to 4, characterized in that.

[0015] (Configuration 6) The thin film contains at least molybdenum. The mask blank according to any one of Configurations 1 to 5, characterized in that.

[0016] (Configuration 7) The thin film is a phase shift film, A portion other than the outer peripheral portion of the phase shift film has a transmittance of 3% or more with respect to light having a wavelength of 365 nm, and a phase difference with respect to light having a wavelength of 365 nm is 150 degrees or more and 210 degrees or less. The mask blank according to any one of Configurations 1 to 6, characterized in that.

[0017] (Configuration 8) A transfer mask including a light-transmissive substrate and a thin film provided on a main surface of the light-transmissive substrate and having a transfer pattern, The thin film is made of a material containing metal, silicon, and nitrogen, The film thickness at the outer peripheral portion of the thin film is smaller than the film thickness at a portion other than the outer peripheral portion of the thin film, The ratio of the nitrogen content to the silicon content in the outer peripheral portion of the thin film is smaller than the ratio of the nitrogen content to the silicon content in the portion other than the outer peripheral portion of the thin film. A transfer mask characterized by this.

[0018] (Configuration 9) The ratio of the film thickness of the thin film in the outer peripheral portion to the film thickness of the thin film in the portion other than the outer peripheral portion is 0.7 or less, which is the transfer mask according to Configuration 8.

[0019] (Configuration 10) The 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 other than the outer peripheral portion of the thin film is 0.84 or less, which is the transfer mask according to Configuration 9.

[0020] (Configuration 11) The oxygen content of the thin film is 10 atomic% or less, which is the transfer mask according to any one of Configurations 8 to 10.

[0021] (Configuration 12) The total content of metal, silicon, and nitrogen in the thin film is 90 atomic% or more, which is the transfer mask according to any one of Configurations 8 to 11.

[0022] (Configuration 13) The thin film contains at least molybdenum, which is the transfer mask according to any one of Configurations 8 to 12.

[0023] (Configuration 14) The thin film is a phase shift film, The portion other than the outer peripheral portion of the phase shift film has a transmittance of 3% or more with respect to light having a wavelength of 365 nm, and a phase difference with respect to light having a wavelength of 365 nm is 150 degrees or more and 210 degrees or less, which is the transfer mask according to any one of Configurations 8 to 13.

[0024] (Configuration 15) A step of peeling the thin film of the mask blank according to any one of Configurations 1 to 7 or the transfer mask according to any one of Configurations 8 to 14 using an etching solution containing ammonium hydrogen fluoride and hydrogen peroxide to obtain a light-transmissive substrate from which the thin film has been removed; A step of newly forming a thin film for pattern formation on the main surface of the light-transmissive substrate from which the thin film has been removed; A method for manufacturing a mask blank, characterized by comprising:

[0025] (Configuration 16) A method for manufacturing a transfer mask, characterized by comprising a step of forming a pattern on the thin film for pattern formation of the mask blank manufactured by the method for manufacturing a mask blank according to Configuration 15 by wet etching.

[0026] (Configuration 17) A step of placing the transfer mask according to any one of Configurations 8 to 14 on a mask stage of an exposure apparatus; 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, characterized by comprising: [Advantages of the Invention]

[0027] According to the present invention, it is possible to suppress deterioration of the shape of the main surface of a light-transmissive substrate after peeling a thin film for pattern formation or a thin film having a transfer pattern, and it is possible to contribute to an improvement in the manufacturing yield after recycling. It is possible to manufacture 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. [Brief Description of the Drawings]

[0028]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0029] First, the background leading to the present invention will be described. The inventors of the present application have been earnestly researching a configuration that can suppress the deterioration of the shape of the main surface of a translucent substrate after peeling a thin film for pattern formation (hereinafter sometimes simply referred to as "thin film") or a thin film having a transfer pattern, and can contribute to an improvement in the manufacturing yield after recycling. The inventors of the present invention prepared a plurality of translucent substrates, formed a thin film for pattern formation on the main surface of each translucent substrate by sputtering, and observed the cross-sectional shapes thereof. As a result, in any of the thin films, the film thickness at the outer peripheral portion was smaller than the film thickness at the portion other than the outer peripheral portion (hereinafter sometimes referred to as "central side portion").

[0030] More specifically, the central side portion of the thin film for pattern formation had a substantially uniform film thickness, but the film thickness decreased toward the peripheral side (side surface side of the translucent substrate) at the outer peripheral portion. Usually, since a pattern is formed in the central side portion of the thin film and no pattern is formed in the outer peripheral portion, there is no problem even if the film thickness decreases at the outer peripheral portion from the viewpoint of transfer performance. However, it was found that there were differences in the peeling situation due to the difference in film thickness between the outer peripheral portion and the central side portion. It is considered that the peeling situation can be improved if the film thicknesses of the central side portion and the outer peripheral portion can be made uniform. However, for that purpose, a significant design change of the film forming apparatus for performing sputtering is required, which is not realistic.

[0031] Therefore, the inventors changed their ideas and further studied the structure of a thin film that can improve the peeling situation while allowing a difference in film thickness between the central part and the outer peripheral part. Generally, when forming a thin film containing metal, silicon, and nitrogen, a sputtering target containing metal and silicon is used, and a film forming process is performed in a gas atmosphere containing nitrogen. For this reason, it is difficult for a large difference to occur in the contents of metal and silicon between the central part and the outer peripheral part. The inventors adjusted conditions such as the nitrogen flow rate in the film forming chamber so that the nitrogen content in the outer peripheral part was different from the nitrogen content in the central part, and formed films on a substrate on which a plurality of thin films with adjusted conditions were prepared. Next, an aqueous solution containing a fluorine compound and an oxidizing agent was brought into contact with each thin film for peeling, and the shape of the main surface of the substrate after peeling was observed. As a result, it was found that in the thin film formed such that the nitrogen flow rate was lower in the outer peripheral part than in the central part, the degree of deterioration of the shape of the main surface was reduced.

[0032] And, although details will be described later, under the same conditions as the substrate in which the deterioration of the shape of the main surface was suppressed, a thin film was formed on another substrate, and a composition analysis was performed on the outer peripheral part and the central part. As a result, it was found that the ratio of the nitrogen content to the silicon content in the outer peripheral part was smaller than the ratio of the nitrogen content to the silicon content in the part other than the outer peripheral part. The inventors further conducted intensive studies and found that in a thin film containing metal, silicon, and nitrogen, if the film thickness in the outer peripheral part is smaller than the film thickness in the part other than the outer peripheral part, and the ratio of the nitrogen content to the silicon content in the outer peripheral part is smaller than the ratio of the nitrogen content to the silicon content in the part other than the outer peripheral part, the deterioration of the shape of the main surface of the translucent substrate after peeling the thin film can be suppressed, which can contribute to an improvement in the manufacturing yield after recycling. The present invention has been made as a result of such intensive studies.

[0033] Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings. The following embodiments are one form when embodying the present invention, and do not limit the present invention within its scope. In the drawings, the same or corresponding parts may be denoted by the same reference numerals, and the description thereof may be simplified or omitted.

[0034] FIG. 1 is a cross-sectional view showing a main part of a mask blank in an embodiment of the present invention. As shown in the figure, the mask blank 10 includes a light-transmissive substrate 20 and a thin film 30 for pattern formation provided on the main surface 21 of the light-transmissive substrate 20. Hereinafter, each element will be described.

[0035] <Light-transmissive substrate 20> The light-transmissive substrate 20 (or may simply be referred to as the substrate 20) is a rectangular plate-like body and has two opposing main surfaces 21, 22, side surfaces 23, and chamfered surfaces (C surfaces) 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. Further, at least one of the two opposing main surfaces 21, 22 is the main surface 21 (may be referred to as one main surface) on which the transfer pattern is to be formed. Also, the main surface 22 on the side opposite to the main surface 21 on which the transfer pattern is to be formed may be referred to as the back surface (or the other main surface).

[0036] The light-transmissive substrate 20 is transparent to exposure light. When assuming no surface reflection loss, the light-transmissive substrate 20 has a transmittance of 85% or more, preferably 90% or more, with respect to the exposure light. The light-transmissive substrate 20 is made of a material containing silicon and oxygen, and is synthetic quartz glass, quartz glass, aluminosilicate glass, soda lime glass, low thermal expansion glass (SiO 2 -TiO 2It can be made of a glass material such as glass. When the light-transmissive substrate 20 is made of a low-thermal-expansion glass, it is possible to suppress the positional change of the phase shift film pattern due to the thermal deformation of the light-transmissive substrate 20. Further, the light-transmissive substrate 20 for a phase shift mask blank used for display device applications is generally a rectangular substrate, and a substrate having a length of the short side of the light-transmissive substrate of 300 mm or more is used. The present invention provides a phase shift mask blank capable of stably transferring a fine phase shift film pattern, for example, less than 2.0 μm, formed on the light-transmissive substrate 20 even when the length of the short side of the light-transmissive substrate 20 is a large size of 300 mm or more.

[0037] <Phase shift film (thin film for pattern formation) 30> On the main surface 21 of the light-transmissive substrate 20, a phase shift film (thin film for pattern formation) 30 is provided. The phase shift film 30 has an outer peripheral portion 32 and a portion other than the outer peripheral portion (central side portion) 31. The film thickness d in the outer peripheral portion 32 2 is smaller than the film thickness d in the central side portion 31 1 . The outer peripheral portion 32 is a region within 10 mm from the boundary with the chamfered surface 24 of the main surface 21 of the light-transmissive substrate 20, and its film thickness d 2 is smaller than the film thickness d of the central side portion 31 1 and can be defined as a region B. Further, the outer peripheral portion 32 is a region within 15 mm from the boundary with the side surface 23 of the main surface 21 of the light-transmissive substrate 20, and its film thickness d 2 is smaller than the film thickness d of the central side portion 31 1 and may be defined as a region B. The film thickness d of the central side portion 31 1 can be defined as the average value of the film thicknesses in the region A of the central side portion 31. The phase shift film 30 contains metal, silicon, and nitrogen. The ratio C of the nitrogen content to the silicon content in the outer peripheral portion 32 of the phase shift film 30 2 (N) / C 2 (Si) is the ratio C of the nitrogen content to the silicon content in the central side portion 31 of the phase shift film 301 (N) / C 1 is smaller than (Si). According to the phase shift film 30 configured in this way, deterioration of the shape of the main surface 21 in the light-transmitting substrate 20 after peeling of the phase shift film 30 can be suppressed.

[0038] The film thickness d in the central portion 31 of the phase shift film 30 1 with respect to the film thickness d in the outer peripheral portion 32 of the phase shift film 30 2 The ratio d 2 / d 1 is preferably 0.7 or less. Further, in the outer peripheral portion 32 within the range where the film thickness ratio d 2 / d 1 is 0.7 or less, the ratio C 2 (N) / C 2 (Si) of the nitrogen content to the silicon content, divided by the ratio C 1 (N) / C 1 (Si) in the central portion 31 of the phase shift film 30, the calculated ratio [C 2 (N) / C 2 (Si)] / [C 1 (N) / C 1 (Si)] is preferably 0.84 or less. By making the ratio [C 2 / d 1 in the outer peripheral portion 32 within the range where d is 0.7 or less, [C 2 (N) / C 2 (Si)] / [C 1 (N) / C 1 (Si)] 0.84 or less, deterioration of the shape of the main surface 21 can be further reduced.

[0039] Also, the ratio [C 2 / d 1 in the outer peripheral portion 32 within the range where d is 0.7 or less, [C 2 (N) / C 2 (Si)] / [C 1 (N) / C 1 (Si)] is more preferably 0.81 or less, and even more preferably 0.77 or less. On the other hand, the film thickness ratio d 2 / d1 The ratio [C 2 (N) / C 2 (Si)] / [C 1 (N) / C 1 (Si)] in the outer peripheral portion 32 within the range of 0.7 or less is preferably 0.06 or more, and more preferably 0.12 or more.

[0040] Also, the ratio d of the film thickness 2 / d 1 In the outer peripheral portion 32 within the range of 0.7 or less, the ratio C of the nitrogen content to the total content of silicon and metal 2 (N) / {C 2 (Si)+C 2 (M)} with respect to the ratio C of the nitrogen content to the total content of silicon and metal in the central portion 31 of the phase shift film 30 1 (N) / {C 1 (Si)+C 1 (M)} calculated by dividing by 2 (N) / {C 2 (Si)+C 2 (M)}] / [C 1 (N) / {C 1 (Si)+C 1 (M)}] is preferably 0.84 or less. The ratio d of the film thickness 2 / d 1 In the outer peripheral portion 32 within the range of 0.7 or less, the ratio [C 2 (N) / {C 2 (Si)+C 2 (M)}] / [C 1 (N) / {C 1 (Si)+C 1 (M)}] is made 0.84 or less, so that the deterioration of the shape of the main surface 21 can be further reduced.

[0041] Also, the ratio d of the film thickness 2 / d 1 In the outer peripheral portion 32 within the range of 0.7 or less, the ratio [C 2 (N) / {C 2 (Si)+C 2 (M)}] / [C 1 (N) / {C 1 (Si)+C 1(M)} is more preferably 0.81 or less, and even more preferably 0.77 or less. On the other hand, the film thickness ratio d 2 / d 1 in the outer peripheral portion 32 within the range of 0.7 or less, the ratio [C 2 (N) / {C 2 (Si)+C 2 (M)}] / [C 1 (N) / {C 1 (Si)+C 1 (M)}] is preferably 0.06 or more, and more preferably 0.12 or more.

[0042] Also, in the outer peripheral portion 32 where the film thickness ratio d 2 / d 1 is 0.7 or less, the ratio of the nitrogen content to the total content of silicon, metal, and oxygen, C 2 (N) / {C 2 (Si)+C 2 (M)+C 2 (O)} is divided by the ratio of the nitrogen content to the total content of silicon, metal, and oxygen, C 1 (N) / {C 1 (Si)+C 1 (M)+C 2 (O)} in the central portion 31 of the phase shift film 30 to calculate the ratio [C 2 (N) / {C 2 (Si)+C 2 (M)+C 2 (O)}] / [C 1 (N) / {C 1 (Si)+C 1 (M)+C 2 (O)}] is preferably 0.84 or less. The ratio [C 2 / d 1 in the outer peripheral portion 32 within the range of 0.7 or less 2 (N) / {C 2 (Si)+C 2 (M)+C 2 (O)}] / [C 1 (N) / {C 1 (Si)+C 1 (M)+C 2By making (O)}] 0.84 or less, the deterioration of the shape of the main surface 21 can be further reduced.

[0043] Also, the ratio d of the film thickness 2 / d 1 in the outer peripheral portion 32 within the range of 0.7 or less, the ratio [C 2 (N) / {C 2 (Si)+C 2 (M)+C 2 (O)}] / [C 1 (N) / {C 1 (Si)+C 1 (M)}+C 2 (O)] is more preferably 0.81 or less, and even more preferably 0.77 or less. On the other hand, the ratio d of the film thickness 2 / d 1 in the outer peripheral portion 32 within the range of 0.7 or less, the ratio [C 2 (N) / {C 2 (Si)+C 2 (M)+C 2 (O)}] / [C 1 (N) / {C 1 (Si)+C 1 (M)+C 2 (O)}] is preferably 0.06 or more, and more preferably 0.12 or more.

[0044] On the other hand, the ratio [C 2 / d 1 in the outer peripheral portion 32 where d is 0.7, the ratio [C 2 (N) / {C 2 (Si)] / [C 1 (N) / {C 1 (Si)] is preferably 0.56 or more, more preferably 0.59 or less, and even more preferably 0.63 or less. The deterioration of the shape of the main surface 21 can be further reduced.

[0045] Also, the ratio d of the film thickness 2 / d 1 in the outer peripheral portion 32 where d is 0.7, the ratio [C 2 (N) / {C 2 (Si)+C 2 (M)}] / [C 1(N) / {C 1 (Si)+C 1 (M)}] is preferably 0.56 or more, more preferably 0.59 or less, and still more preferably 0.63 or less. The deterioration of the shape of the main surface 21 can be further reduced.

[0046] Also, the ratio d of the film thickness 2 / d 1 The ratio [C 2 (N) / {C 2 (Si)+C 2 (M)+C 2 (O)}] / [C 1 (N) / {C 1 (Si)+C 1 (M)+C 2 (O)}] in the outer peripheral portion 32 where d is 0.7 is preferably 0.56 or more, more preferably 0.59 or less, and still more preferably 0.63 or less. The deterioration of the shape of the main surface 21 can be further reduced.

[0047] As the metal contained in the phase shift film 30, transition metals such as molybdenum (Mo), tantalum (Ta), tungsten (W), titanium (Ti), and zirconium (Zr) are suitable, and it is preferable to contain at least molybdenum. The nitrogen content contained in the phase shift film 30 is preferably more than 10 atomic% and 50 atomic% or less. More preferably, it is 15 atomic% or more and 45 atomic% or less. The total content of the metal, silicon, and nitrogen in the phase shift film 30 is preferably 90 atomic% or more, and more preferably 92 atomic% or more. Also, the ratio of the metal content to the total content of the metal and silicon in the phase shift film 30 is preferably 0.5 or less, more preferably 0.45 or less, and still more preferably 0.35 or less. The phase shift film 30 may contain oxygen. The oxygen content contained 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 the phase difference with respect to the exposure light. The phase shift film 30 preferably further has a function of adjusting the reflectance with respect to the light incident from the light-transmissive substrate 20 side (hereinafter sometimes referred to as the back surface reflectance). The phase shift film 30 can be formed by a sputtering method.

[0048] The transmittance of the portion other than the outer peripheral portion of the phase shift film 30 with respect to the exposure light satisfies the value required for the phase shift film 30. The transmittance of the portion other than the outer peripheral portion of the phase shift film 30 is preferably 3% or more, more preferably 10% or more, with respect to the light of a predetermined wavelength included in the exposure light (hereinafter referred to as the representative wavelength, for example, light having a wavelength of 365 nm). Also, it is preferably 70% or less, more preferably 65% or less, with respect to the representative wavelength. That is, when the exposure light is a composite light including light in the wavelength range of 313 nm or more and 436 nm or less, the portion other than the outer peripheral portion of the phase shift film 30 has the above-described transmittance with respect to the light of the representative wavelength included in that wavelength range. For example, when the exposure light is a composite light including i-line, h-line, and g-line, the portion other than the outer peripheral portion of the phase shift film 30 has the above-described transmittance with respect to any one of the i-line, h-line, and g-line. The transmittance can be measured using a phase shift measurement device or the like.

[0049] The phase difference of the light transmitted through the portion other than the outer peripheral portion of the phase shift film 30 satisfies the value required for the phase shift film 30. The phase difference of the portion other than the outer peripheral portion of the phase shift film 30 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 with respect to the light of the representative wavelength included in the exposure light. Due to this property, the phase of the light of the representative wavelength included in the exposure light can be changed within a predetermined range of the phase difference. Therefore, a predetermined phase difference occurs between the light of the representative wavelength transmitted through the portion other than the outer peripheral portion of the phase shift film 30 and the light of the representative wavelength transmitted only through the light-transmissive substrate 20. That is, when the exposure light is a composite light including light in the wavelength range of 313 nm or more and 436 nm or less, the portion other than the outer peripheral portion of the phase shift film 30 has the above-described phase difference with respect to the light of the representative wavelength included in that wavelength range. For example, when the exposure light is a composite light including i-line, h-line, and g-line, the portion other than the outer peripheral portion of the phase shift film 30 has the above-described 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 difference measuring device or the like.

[0050] In addition, the phase shift film 30 of the phase shift mask blank 10 is required to have high chemical resistance (cleaning resistance). In order to enhance the chemical resistance (cleaning resistance) of the phase shift film 30, it is effective to increase the film density. There is a correlation between the film density and the film stress of the phase shift film 30. Considering the chemical resistance (cleaning resistance), the film stress of the phase shift film 30 is preferably high. On the other hand, it is necessary to consider the positional deviation when forming the phase shift film pattern and the loss of the phase shift film pattern with respect to the film stress of the phase shift film 30. From the above viewpoints, the film stress of the phase shift film 30 is preferably 0.4 GPa or more and 0.8 GPa or less.

[0051] <Etching mask film 40> The phase shift mask blank 10 in the present embodiment may have an etching mask film 40 (see FIG. 4. In FIG. 4, for simplicity, illustration of the outer peripheral portion and the like is omitted. The same applies to FIG. 5). The etching mask film 40 is disposed above the phase shift film 30 and is made of a material having etching resistance to the etching solution for etching the phase shift film 30. Further, the etching mask film 40 may have a function of blocking the transmission of exposure light, and furthermore, may have a function of reducing the film surface reflectance. The etching mask film 40 is composed of, for example, a chromium-based material. More specifically, examples of the chromium-based material include chromium (Cr), or a material containing chromium (Cr) and at least one of oxygen (O), nitrogen (N), and carbon (C). Alternatively, a material containing chromium (Cr) and at least one of oxygen (O), nitrogen (N), and carbon (C), and further containing fluorine (F) can be mentioned. For example, examples of the material constituting the etching mask film 40 include Cr, CrO, CrN, CrF, CrCO, CrCN, CrON, CrCON, and CrCONF. The etching mask film 40 can be formed by a sputtering method.

[0052] When the etching mask film 40 has a function of blocking the transmission of exposure light, in the portion where the phase shift film 30 and the etching mask film 40 are laminated, the optical density with respect to the exposure light 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.

[0053] Note that although the phase shift mask blank 10 shown in FIG. 1 includes the etching mask film 40 on the phase shift film 30, the present invention can also be applied to a phase shift mask blank including the etching mask film 40 on the phase shift film 30 and a resist film on the etching mask film 40.

[0054] <Manufacturing method of phase shift mask blank (mask blank)> Next, a method for manufacturing the phase shift mask blank (mask blank) 10 of this embodiment will be described. The phase shift mask blank 10 is manufactured by performing the following phase shift film forming step and etching mask film forming step. Hereinafter, each step will be described in detail.

[0055] 1. Phase shift film forming step First, a light transmissive substrate 20 is prepared. The light transmissive substrate 20 may be made of any glass material such as synthetic quartz glass, quartz glass, aluminosilicate glass, soda lime glass, low thermal expansion glass (SiO 2 -TiO 2 glass, etc.).

[0056] Next, a phase shift film 30 is formed on the light transmissive substrate 20 by sputtering. The film formation of the phase shift film 30 is performed using a sputtering target containing a transition metal and silicon, which is the main component of the material constituting the phase shift film 30, or a sputtering target containing a transition metal, silicon, oxygen and / or nitrogen, for example, in a sputtering gas atmosphere composed 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 sputtering gas atmosphere composed of a mixed gas of the above inert gas and an active gas containing at least one selected from the group consisting of oxygen gas, nitrogen monoxide gas and nitrogen dioxide gas. The film thickness d 2 at the outer peripheral portion 32 of the phase shift film 30 is formed to be smaller than the film thickness d 1 at the central portion 31 of the phase shift film 30. At this time, the conditions such as the flow rate of nitrogen in the film formation chamber are adjusted so that the flow rate of nitrogen is lower at the outer peripheral portion 32 than at the central portion 31 of the phase shift film 30. Thereby, the film thickness d 2 at the outer peripheral portion 32 of the phase shift film 30 becomes smaller than the film thickness d 1 at the central portion 31 of the phase shift film 30, and the ratio C 2 (N) / C2 (C) The ratio C of the nitrogen content to the silicon content in the silicon in the central portion 31 1 (N) / C 1 (Si) is smaller.

[0057] The composition and thickness of the phase shift film 30 are adjusted so that the phase shift film 30 in the portion other than the outer peripheral portion has the above-described phase difference and transmittance. The composition of the phase shift film 30 can be controlled by the content ratio of the elements constituting the sputtering target (for example, the ratio of the content of the transition metal to the content of silicon), the composition and flow rate of the sputtering gas, and the like. The thickness of the phase shift film 30 can be controlled by the sputtering power, the sputtering time, and the like. Further, when the sputtering apparatus is an in-line type sputtering apparatus, the thickness of the phase shift film 30 can also be controlled by the conveyance speed of the substrate. In this way, control is performed so that the total content of metal, silicon, and nitrogen and the content of oxygen in the phase shift film 30 are within a desired range.

[0058] 3. Etching mask film formation step After performing a surface treatment for adjusting the surface oxidation state of the surface of the phase shift film 30, an etching mask film 40 is formed on the phase shift film 30 by a sputtering method. In this way, the phase shift mask blank 10 is obtained.

[0059] The formation of the etching mask film 40 is carried out using a sputtering target containing chromium or a chromium compound (such as chromium oxide, chromium nitride, chromium carbide, chromium oxynitride, chromium oxynitride carbide, etc.) in a sputtering gas atmosphere composed 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 composed 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 oxygen gas, nitrogen gas, nitrogen monoxide gas, nitrogen dioxide gas, carbon dioxide gas, hydrocarbon gas, and fluorine gas. Examples of the hydrocarbon gas include methane gas, butane gas, propane gas, styrene gas, etc.

[0060] <Phase Shift Mask (Transfer Mask) and Method for Manufacturing the Same> FIG. 5 is a schematic diagram showing the manufacturing process of the phase shift mask (transfer mask) in the embodiment of the present invention. The method for manufacturing a phase shift mask shown in FIG. 5 is a method for manufacturing a phase shift mask using the phase shift mask blank 10 shown in FIG. 4. As shown in FIG. 5(e), in the phase shift mask 100, a phase shift film pattern 30a, which is a transfer pattern, is formed on the phase shift film 30 of the mask blank 10, and a second etching mask film pattern 40b that functions as a light-shielding pattern is formed on the etching mask film 40. This phase shift mask 100 has the same technical features as the mask blank 10. Matters regarding the transparent substrate 20, the central portion 31 of the phase shift film 30, the outer peripheral portion 32, and the etching mask film 40 in the phase shift mask 100 are the same as those of the mask blank 10. The method for manufacturing a phase shift mask includes a step of forming a resist film on the phase shift mask blank 10, and by drawing and developing a desired pattern on the resist film, a resist film pattern 50 is formed (the first resist film pattern forming step). Using the resist film pattern 50 as a mask, the etching mask film 40 is patterned by wet etching to form an etching mask film pattern 40a (the first etching mask film pattern forming step), and using the etching mask film pattern 40a as a mask, the phase shift film 30 is wet-etched to form a phase shift film pattern 30a on the transparent substrate 20 (the phase shift film pattern forming step). And it further includes a second resist film pattern forming step and a second etching mask film pattern forming step. Hereinafter, each step will be described.

[0061] 1. First resist film pattern forming step In the first resist film pattern forming step, first, a resist film is formed on the etching mask film 40 of the phase shift mask blank 10. The resist film material to be used is not particularly limited. For example, it may be any material that is sensitive to laser light having any wavelength selected from the wavelength range of 350 nm to 436 nm. Also, the resist film may be either positive type or negative type. Thereafter, a desired pattern is drawn on the resist film using laser light having any 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. 5(a).

[0062] 2. First etching mask film pattern forming step 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 formed of a chromium-based material containing chromium (Cr). The etching solution for etching 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 ammonium cerium (IV) nitrate and perchloric acid can be mentioned. Thereafter, the first resist film pattern 50 is peeled off as shown in FIG. 5(b) using a resist stripping solution or by ashing. In some cases, the next phase shift film pattern forming step may be performed without peeling off the first resist film pattern 50.

[0063] 3. Phase shift film pattern forming step In the first phase shift film pattern forming 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. 5(c). Examples of the phase shift film pattern 30a include a line and space pattern and a hole pattern. The etching solution for etching the phase shift film 30 is not particularly limited as long as it can selectively etch the phase shift film 30. For example, an etching solution containing ammonium fluoride, phosphoric acid, and hydrogen peroxide, and an etching solution containing ammonium hydrogen fluoride and hydrogen chloride can be mentioned.

[0064] 4. Second resist film pattern forming step In the second resist film pattern forming step, first, a resist film covering the first etching mask film pattern 40a is formed. The resist film material to be used is not particularly limited, similar to the resist film material in the first resist film pattern forming step. Thereafter, a desired pattern is drawn on the resist film using laser light having any 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. Note that depending on the transmittance of the phase shift film 30 with respect to the exposure light, the pattern drawn on the resist film may be a pattern without 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. 5(d).

[0065] 5. Second etching mask film pattern forming step 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. 5(e). The first etching mask film pattern 40a is formed from a chromium-based material containing chromium (Cr). The etching solution for etching 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 ammonium cerium (IV) nitrate and perchloric acid can be mentioned. Thereafter, the second resist film pattern 60 is peeled off using a resist stripper or by ashing. In this way, the phase shift mask 100 is obtained. In the above description, the case where the etching mask film 40 has a function of blocking the transmission of exposure light has been described. However, when the etching mask film 40 has only the function of a hard mask when etching the phase shift film 30, in the above description, the second resist film pattern forming step and the second etching mask film pattern forming step are not performed. After the phase shift film pattern forming step, the first etching mask film pattern is peeled off to produce the phase shift mask 100.

[0066] According to this method for manufacturing a phase shift mask, since the phase shift mask blank of Embodiment 1 is used, a phase shift film pattern having a good cross-sectional shape and small CD variation can be formed. Therefore, a phase shift mask capable of accurately transferring a high-definition phase shift film pattern can be manufactured. The phase shift mask manufactured in this way can cope with the miniaturization of line and space patterns and contact holes.

[0067] 〈Method for manufacturing a new mask blank〉 Next, a method for recycling the above-described phase shift mask blank 10 or phase shift mask 100 to manufacture a new mask blank 10 and a transfer mask 100 will be described. First, prepare a phase shift mask blank 10 or a phase shift mask 100 to be recycled. The structure of each of the phase shift mask blank 10 or the phase shift mask 100 to be recycled is as described above. Next, perform a step of removing the etching mask film 40 in the phase shift mask blank 10 or the etching mask film pattern 40b in the phase shift mask 100 using a stripping solution. When the etching mask film 40 or the etching mask film pattern 40b is composed of a chromium-based material, it can be performed by supplying an etching solution for chromium composed of pure water containing cerium (IV) ammonium nitrate ((NH 4 ) 2 Ce(NO 3 ) 6 ) and perchloric acid (HClO 4 ) to the etching mask film 40 or the etching mask film pattern 40b and performing etching.

[0068] Then, perform a step of removing the phase shift film (thin film) 30 in the phase shift mask blank 10 or the phase shift film pattern (thin film having a transfer pattern) 30a in the phase shift mask 100 using a stripping solution. The removal of the phase shift film 30 or the phase shift film pattern 30a can be performed using an etching solution containing ammonium hydrogen fluoride and hydrogen peroxide. This etching solution contains at least one fluorine compound selected from hydrofluoric acid, hexafluorosilicic acid, and ammonium hydrogen fluoride, and at least one oxidizing agent selected from hydrogen peroxide, nitric acid, and sulfuric acid, and is preferably performed by bringing it into contact with an aqueous solution containing 0.1 to 0.8 wt% of the fluorine compound and 0.5 to 4.0 wt% of the oxidizing agent.

[0069] As described above, the film thickness d 2 in the outer peripheral portion 32 of the phase shift film 30 or the phase shift film pattern 30a 1 is smaller than the film thickness d 2(N) / C 2 The ratio C of the nitrogen content to the silicon content of silicon in the central portion 31 1 (N) / C 1 is smaller than (Si). Thereby, when performing the phase shift film 30 or the phase shift film pattern 30a using the above-described etching solution, the etching rate in the outer peripheral portion 32 can be suppressed more than the etching rate in the central portion 31. Thereby, the difference between the time required for removing the outer peripheral portion 32 having a smaller film thickness than the central portion 31 and the time required for removing the central portion 31 can be significantly shortened. Therefore, it becomes possible to improve the in-plane uniformity of the main surface 21 of the translucent substrate 20 after peeling the phase shift film 30 or the phase shift film pattern 30a. In this way, a translucent substrate from which the phase shift film 30 or the phase shift film pattern 30a has been removed is obtained.

[0070] For the main surfaces 21 and 22 of the translucent substrate 20 after peeling the phase shift film 30 or the phase shift film pattern 30a, measurement of the surface shape (measurement of flatness) is performed using an inspection apparatus. Then, according to the inspection result, a predetermined polishing process and cleaning process are appropriately performed. Thereafter, an evaluation process is performed on whether the translucent substrate 20 satisfies the quality as a recycled substrate (such as whether the flatness of the main surface 21 and the thickness of the translucent substrate 20 satisfy the standards). For the translucent substrate 20 determined to satisfy, a process of newly forming a thin film for pattern formation is performed. In this way, a new mask blank can be manufactured. When the new mask blank is the phase shift mask blank 10, the process of newly forming a thin film for pattern formation is performed in the same manner as the above-described <Method for manufacturing a phase shift mask blank (mask blank)>. Note that this new mask blank does not necessarily have to be the phase shift mask blank 10, and may be, for example, a mask blank for binary use.

[0071] <Method for manufacturing a new transfer mask> A method for manufacturing a new transfer mask using the mask blank manufactured by the above-described method for manufacturing a new mask blank will be described. This method for manufacturing a new transfer mask includes a step of forming a pattern on the thin film for pattern formation of the newly manufactured mask blank by wet etching. When the newly manufactured mask blank is a phase shift mask blank 10, a phase shift mask pattern 30a can be formed by wet etching on the thin film for pattern formation (phase shift film) 30 of this mask blank 10 as described in the above <Phase Shift Mask (Transfer Mask) and Method for Manufacturing the Same>. Note that even when this new mask blank is, for example, a mask blank for binary use, a pattern can be formed by performing wet etching using an etching solution containing ammonium cerium (IV) nitrate and perchloric acid on the thin film for pattern formation (for example, an etching mask film made of a chromium-based material having light-shielding properties) formed on the translucent substrate 20.

[0072] <Method for Manufacturing Display Device> The display device is manufactured by performing a step of using the above-described transfer mask (mask placement step) and a step of exposing and transferring a transfer pattern to a resist film on the display device (pattern transfer step). Hereinafter, each step will be described in detail.

[0073] 1. Placement Step In the placement step, the transfer mask is placed on the mask stage of the exposure apparatus. Here, the transfer mask may be either a phase shift mask (transfer mask) 100 manufactured using the phase shift mask blank 10 or a new transfer mask manufactured by the above-described method for manufacturing a new transfer mask. The transfer mask is arranged so as to face the resist film formed on the display device substrate through the projection optical system of the exposure apparatus.

[0074] 2. Pattern Transfer Step In the pattern transfer process, the exposure light is irradiated onto the transfer mask, and the phase shift film pattern is transferred onto the resist film formed on the display device substrate. The exposure light is composite light including light of a plurality of 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 with a filter or the like. For example, the exposure light is composite light including i-line, h-line, and g-line, or monochromatic light of i-line. When composite light is used as the exposure light, the exposure light intensity can be increased to increase the throughput, so that the manufacturing cost of the display device can be reduced.

[0075] According to this manufacturing method of the display device, CD error can be suppressed, and a high-definition display device having high resolution, fine line and space patterns, and contact holes can be manufactured.

Example

[0076] Example 1. A. Phase shift mask blank and its manufacturing method To manufacture the phase shift mask blank of Example 1, first, a synthetic quartz glass substrate of 1214 size (1220 mm × 1400 mm) was prepared as the light-transmissive substrate 20.

[0077] Thereafter, the synthetic quartz glass substrate was mounted on a tray (not shown) with the main surface facing downward and carried into the chamber of an in-line type sputtering apparatus. To form the phase shift film 30 on the main surface 21 of the light-transmissive substrate 20, first, with the inside of the first chamber at a predetermined degree of vacuum, argon (Ar) gas and oxygen gas (O 2 ) and nitrogen (N 2)A mixed gas with a gas was introduced, and by reactive sputtering using a first sputtering target containing molybdenum and silicon (molybdenum:silicon = 1:4), an oxynitride of molybdenum silicide containing molybdenum, silicon, oxygen, and nitrogen was deposited on the main surface of the translucent substrate 20. At this time, the amount of nitrogen gas in the chamber was adjusted by adjusting the flow rate conditions of nitrogen in the film formation chamber and the arrangement of the gas inlets and outlets so that it was less in the outer peripheral portion 32 than in the central portion 31 of the phase shift film 30. And in the central portion 31 of the phase shift film 30, a phase shift film 30 with a film thickness d 1 of 110 nm was formed. The film thickness d 1 was calculated as the average value of the film thicknesses at 25 measurement points, 5 in the vertical direction and 5 in the horizontal direction, within a 30-mm rectangular region in the central portion 31. Also, in the region B of the outer peripheral portion 32, all the film thicknesses d 2 were smaller than the film thickness d 1 . The region B of the outer peripheral portion 32 was formed over a range of 4 mm to 7 mm from the boundary of the chamfered surface 24 on the main surface 21 of the translucent substrate 20 and was a region within 10 mm from the boundary of the chamfered surface 24 of the main surface 21.

[0078] Next, the translucent substrate 20 with the phase shift film 30 was carried into the second chamber, and a mixed gas of argon (Ar) gas and nitrogen (N 2 ) gas was introduced in a state where the inside of the second chamber was at a predetermined degree of vacuum. Then, by reactive sputtering using a second sputtering target made of chromium, chromium nitride (CrN) containing chromium and nitrogen was formed on the phase shift film 30 (film thickness 15 nm). Next, in a state where the inside of the third chamber was at a predetermined degree of vacuum, a mixed gas of argon (Ar) gas and methane (CH 4 ) gas was introduced, and chromium carbide (CrC) containing chromium and carbon was formed on CrN by reactive sputtering using a third sputtering target made of chromium (film thickness 60 nm). Finally, in a state where the inside of the fourth chamber was at a predetermined degree of vacuum, a mixed gas of argon (Ar) gas and methane (CH 4 ) gas and nitrogen (N2 ) A mixed gas of a gas and oxygen (O 2 ) and a gas (Ar + CH 4 ) was introduced, and chromium carbonitride oxide (CrCON) containing chromium, carbon, oxygen, and nitrogen was formed on CrC by reactive sputtering using a fourth sputtering target made of chromium (film thickness: 30 nm). As described above, an etching mask film 40 having a laminated structure of a CrN layer, a CrC layer, and a CrCON layer was formed on the phase shift film 30. In this way, a phase shift mask blank 10 having a phase shift film 30 and an etching mask film 40 formed on the light-transmissive substrate 20 was obtained.

[0079] Regarding the phase shift film 30 of the obtained phase shift mask blank 10, the transmittance and the phase difference of the central portion 31 were measured by the MPM-100 manufactured by Lasertec Corporation. For the measurement of the transmittance and the phase difference of the phase shift film 30, a substrate with a phase shift film (dummy substrate) on which the phase shift film 30 was formed on the main surface of a synthetic quartz glass substrate, which was fabricated by being set in the same tray, was used. The transmittance and the phase difference of the phase shift film 30 were measured by taking out the substrate with a phase shift film (dummy substrate) from the chamber and measuring it before forming the etching mask film 40. As a result, the transmittance was about 5.2% (wavelength: 365 nm), and the phase difference was 176 degrees (wavelength: 365 nm).

[0080] For another light-transmissive substrate, a phase shift film and an etching mask film were formed under the above-described conditions. Then, depth-directional composition analysis by X-ray photoelectron spectroscopy (XPS) was performed on the outer peripheral portion and the central portion of the phase shift film. FIG. 2 is a diagram showing the results of depth-directional composition analysis for the central portion (portion other than the outer peripheral portion) of the phase shift mask blank of Example 1. FIG. 3 is a diagram showing the results of depth-directional composition analysis for the outer peripheral portion of the phase shift mask blank of Example 1. Here, in FIG. 2, in the central portion 31, the measured film thickness d 1It shows the composition analysis results at the point where the thickness became approximately the same as the average film thickness. Therefore, it can be said that the composition analysis results shown in FIG. 2 represent the average characteristics of the entire central portion 31. Also, in FIG. 3, in the outer peripheral portion 32, the measured film thickness d 2 shows the composition analysis results at the point where it is 77 nm. That is, the ratio of the film thickness d 2 / d 1 is 0.7. The horizontal axis in FIGS. 2 and 3 indicates the milling time (minutes) with respect to the phase shift mask blank 10 based on the outermost surface of the etching mask film 40, and the vertical axis indicates the content (atomic %). In FIG. 3, each curve shows the change in the content of silicon (Si), nitrogen (N), oxygen (O), chromium (Cr), and molybdenum (Mo), respectively.

[0081] As shown in FIGS. 2 and 3, in the depth-direction composition analysis results by XPS for the phase shift mask blank 10, between the interface between the phase shift film 30 and the etching mask film 40 (the position where the ratio of the transition metal decreases from the phase shift film 30 toward the etching mask film 40 and the content of the transition metal first becomes 0 atomic %) and the interface between the phase shift film 30 and the light-transmissive substrate 20 (the position where the ratio of the transition metal decreases from the phase shift film 30 toward the light-transmissive substrate 20 and the content of the transition metal first becomes 0 atomic %), in the region of the phase shift film 30, it was found that the nitrogen content in the outer peripheral portion 32 is smaller than the nitrogen content in the central portion (the portion other than the outer peripheral portion) 31. Also, in both the outer peripheral portion 32 and the central portion 31, it was found that the oxygen content is 10 atomic % or less, and the total content of metal, silicon, and nitrogen is 90 atomic % or more.

[0082] From the results of FIG. 2, when calculating the average value of each composition in the central portion 31 of the phase shift film 30, the silicon content C 1 (Si) is 41.3 atomic %, the molybdenum content C 1 (Mo) is 16.3 atomic %, the nitrogen content C 1 (N) is 35.6 atomic %, the oxygen content C 1 (O) is 5.4 atomic %, the carbon content C1 (C) was 1.1 atomic %, the chromium content C 1 (Cr) was 0.3 atomic %. Also, from the results of FIG. 3, for the outer peripheral portion 32 of the phase shift film 30 (the point where the ratio d of the film thickness 2 / d 1 was 0.7.), when the average value of each composition was calculated, the silicon content C 2 (Si) was 48.7 atomic %, the molybdenum content C 2 (Mo) was 20.1 atomic %, the nitrogen content C 2 (N) was 29.1 atomic %, the oxygen content C 2 (O) was 1.0 atomic %, the carbon content C 2 (C) was 0.9 atomic %, the chromium content C 2 (Cr) was 0.2 atomic %.

[0083] From these results, the ratio C 1 (N) / C 1 (Si) in the central side portion (the portion other than the outer peripheral portion) 31 was 0.862, the ratio C 1 (N) / {C 1 (Si)+C 1 (Mo)} was 0.618, the ratio C 1 (N) / {C 1 (Si)+C 1 (Mo)+C 1 (O)} was 0.565. Also, the ratio C 2 (N) / C 2 (Si) in the outer peripheral portion 32 was 0.598, the ratio C 2 (N) / {C 2 (Si)+C 2 (Mo)} was 0.423, and the ratio C 2 (N) / {C 2 (Si)+C 2 (Mo)+C 2 (O)} was 0.417. That is, for each of the above ratios, the outer peripheral portion 32 was lower than the central side portion 31.

[0084] Furthermore, the ratio [C 2 (N) / C 2 (Si)] / [C 1 (N) / C1 (Si) is 0.694, the ratio [C 2 (N) / {C 2 (Si)+C 2 (M)}] / [C 1 (N) / {C 1 (Si)+C 1 (M)}] is 0.685, the ratio [C 2 (N) / {C 2 (Si)+C 2 (M)+C 2 (O)}] / [C 1 (N) / {C 1 (Si)+C 1 (M)+C 2 (O)}] was also found to be 0.738. All of the above ratios were less than 0.84.

[0085] B. Phase Shift Mask and Method for Manufacturing the Same Regarding the phase shift mask blank 10 manufactured as described above, a phase shift mask 100 in which a phase shift film pattern 30a and a light-shielding pattern having a laminated structure of the phase shift film pattern 30a and an etching mask film pattern 40b were formed in a transfer pattern formation region on a translucent substrate 20 was obtained by the procedure shown in FIG. 5.

[0086] When the CD variation of the phase shift film pattern of the phase shift mask was measured with a SIR8000 manufactured by Seiko Instruments Nanotechnology, Inc., the CD variation was good. C. Method for Manufacturing a Display Device Therefore, it can be said that when the phase shift mask of Example 1 is set on the mask stage of an exposure apparatus and exposed and transferred onto a resist film on a display device, a fine pattern can be transferred with high precision.

[0087] D. Method for Manufacturing a New Mask Blank Ten phase shift mask blanks 10 or phase shift masks 100 in Example 1 were prepared respectively, and ammonium cerium (IV) nitrate ((NH 4 )2 Ce(NO 3 ) 6 ) and perchloric acid (HClO 4 ) was supplied to the etching mask film 40 or the etching mask film pattern 40b made of pure water containing the same, and the step of removing it was carried out. Then, the phase shift film (thin film) 30 in the phase shift mask blank 10 or the phase shift film pattern (thin film having a transfer pattern) 30a in the phase shift mask 100 was removed using a stripping solution. In this step, as the aqueous solution, a mixed aqueous solution of ammonium hydrogen fluoride (0.5 wt%) + hydrogen peroxide (2.0 wt%) + pure water (97.5 wt%) was used. Subsequently, the main surfaces 21, 22 of the substrate 20 from which the phase shift film (thin film) 30 or the phase shift film pattern (thin film having a transfer pattern) 30a was removed were inspected for surface shape, in-plane uniformity, etc. using an inspection apparatus. In any of the substrates 20, the in-plane uniformity was within the allowable range, and good results were obtained. Thereafter, a predetermined polishing step and cleaning step were appropriately performed on the main surfaces 21, 22 of the substrate 20 using a polishing liquid containing known free abrasive grains such as cerium oxide and colloidal silica and a polishing pad. Thereafter, an evaluation step was performed on whether the light-transmissive substrate 20 satisfies the quality as a recycled substrate, and as a result, it was obtained that any of the substrates 20 satisfies the quality. And, as described in <A. Phase shift mask blank and its manufacturing method>, <B. Phase shift mask and its manufacturing method>, <C. Manufacturing method of display device> in Example 1, a new phase shift mask blank, phase shift mask, and display device were manufactured, and good results were obtained in all cases. As described above, according to this embodiment, it is possible to improve the in-plane uniformity of the main surface of the translucent substrate after peeling off the thin film for pattern formation or the thin film having a transfer pattern, and it is possible to contribute to the improvement of the manufacturing yield after recycling. It is possible to manufacture 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.

[0088] Comparative Example 1. In order to manufacture the phase shift mask blank 10 of Comparative Example 1, in the same manner as in Example 1, a synthetic quartz glass substrate of 1214 size (1220 mm × 1400 mm) was prepared as the translucent substrate 20. The synthetic quartz glass substrate was carried into the chamber of an in-line type sputtering apparatus. In Comparative Example 1, different from Example 1, the phase shift film 30 was formed without setting conditions such as the flow rate of nitrogen in the film formation chamber. Then, the same sputtering target materials as in Example 1 were used as the first sputtering target, the second sputtering target, the third sputtering target, and the fourth sputtering target. Then, the etching mask film 40 was formed in the same manner as in Example 1. In this way, a phase shift mask blank 10 having a phase shift film 30 and an etching mask film 40 formed on the translucent substrate 20 was obtained.

[0089] Regarding the phase shift film (phase shift film with its surface washed with pure water) 30 of the obtained phase shift mask blank 10, the transmittance and the phase difference of the central portion 31 were measured using an MPM-100 manufactured by Lasertec Corporation. For the measurement of the transmittance and the phase difference of the phase shift film, a substrate with a phase shift film (dummy substrate) having the phase shift film 30 formed on the main surface of the synthetic quartz glass substrate, which was set in the same tray and fabricated, was used. The transmittance and the phase difference of the phase shift film 30 were measured by taking out the substrate with a phase shift film (dummy substrate) from the chamber before forming the etching mask film. As a result, the transmittance was about 5.2% (wavelength: 365 nm) and the phase difference was 176 degrees (wavelength: 365 nm).

[0090] Also, for another translucent substrate, a phase shift film and an etching mask film were formed under the same conditions as in Comparative Example 1. Then, depth-direction composition analysis by X-ray photoelectron spectroscopy (XPS) was performed on the outer peripheral portion and the central portion of the phase shift film. The composition analysis results for the central portion of the phase shift film were equivalent to those of Example 1 shown in FIG. 2. On the other hand, the composition analysis results for the outer peripheral portion of the phase shift film were equivalent to the composition analysis results for the central portion of the phase shift film. That is, the ratio C 1 (N) / C 1 (Si) of the nitrogen content to the silicon content in the central portion (portion other than the outer peripheral portion) and the ratio C 2 (N) / C 2 (Si) of the nitrogen content to the silicon content in the outer peripheral portion had equivalent values.

[0091] Similarly, the ratio C 1 (N) / {C 1 (Si)+C 1 (Mo)} and the ratio C 2 (N) / {C 2 (Si)+C2(Mo)} had equivalent values, and the ratio C1(N) / {C1(Si)+C 1 (Mo)+C 1 (O)} and C 2 (N) / {C 2 (Si)+C 2 (Mo)+C 2 (O)} had equivalent values. Therefore, the ratios [C 2 (N) / C 2 (Si)] / [C 1 (N) / C 1 (Si)], [C 2 (N) / {C 2 (Si)+C 2 (M)}] / [C 1 (N) / {C 1 (Si)+C 1 (M)}], and [C 2 (N) / {C 2 (Si)+C 2 (M)+C 2 (O)}] / [C 1 (N) / {C 1 (Si)+C 1(M) + C 2 (O)}] were both weak, significantly exceeding 0.84.

[0092] Also, regarding the phase shift film, when the flatness change was measured using UltraFLAT 200M (manufactured by Corning TROPEL) and the film stress was calculated, it was 0.46 GPa. This phase shift film 30 had small changes in both the transmittance and the phase difference with respect to the chemical solutions (sulfuric acid peroxide, ammonia peroxide, ozone water) used for cleaning the phase shift mask, and had high chemical resistance and cleaning resistance.

[0093] B. Phase Shift Mask and Method for Manufacturing the Same Using the phase shift mask blank manufactured as described above, a phase shift mask was manufactured by the same method as in Example 1. When the CD variation of the phase shift film pattern of the phase shift mask was measured using SIR8000 manufactured by Seiko Instruments Nanotechnology, the CD variation was good.

[0094] C. Method for Manufacturing a Display Device Therefore, when the phase shift mask of this Comparative Example 1 was set on the mask stage of the exposure apparatus and exposed and transferred onto the resist film on the display device, it can be said that fine patterns can be transferred with high precision.

[0095] D. Method for Manufacturing a New Mask Blank Ten pieces each of the phase shift mask blank 10 or the phase shift mask 100 in Comparative Example 1 were prepared, and for each etching mask film 40 or etching mask film pattern 40b, a chromium etching solution composed of pure water containing ammonium cerium (IV) nitrate ((NH 4 ) 2 Ce(NO 3 ) 6 ) and perchloric acid (HClO 4 ) was supplied to the etching mask film 40 or the etching mask film pattern 40b, and a step of removing it was carried out.

[0096] Then, a step of removing the phase shift film (thin film) 30 in the phase shift mask blank 10 or the phase shift film pattern (thin film having a transfer pattern) 30a in the phase shift mask 100 using a stripping solution was carried out. In this step, as the aqueous solution, a mixed aqueous solution of ammonium hydrogen fluoride (0.5 wt%) + hydrogen peroxide (2.0 wt%) + pure water (97.5 wt%) was used.

[0097] Subsequently, with respect to the main surfaces 21, 22 of the substrate 20 from which the phase shift film (thin film) 30 or the phase shift film pattern (thin film having a transfer pattern) 30a has been removed, a predetermined polishing step and cleaning step were appropriately performed using a polishing liquid containing known free abrasive grains such as cerium oxide and colloidal silica, and a polishing pad. In any of the substrates 20, more polishing steps were required than in the polishing step of Example 1, and the polishing amount also increased.

[0098] Thereafter, the surface shape of the light-transmissive substrate 20 was measured (measurement of flatness, etc.) and the thickness of the substrate was measured using an inspection apparatus. From those results, an evaluation step was performed on whether the quality as a recycled substrate was satisfied. As a result, it was evaluated that 5 substrates 20 did not satisfy the required plate thickness standard and did not meet the quality requirements. That is, out of the initially prepared 10 substrates 20, only 5 substrates were determined to meet the quality requirements.

[0099] Then, as described in <A. Phase Shift Mask Blank and Its Manufacturing Method>, <B. Phase Shift Mask and Its Manufacturing Method>, and <C. Manufacturing Method of Display Device> in Comparative Example 1, when a new phase shift mask blank, phase shift mask, and display device were manufactured, the performance was equivalent to or lower than that of the phase shift mask of Comparative Example 1 before recycling. And subsequent recycling could not be carried out.

[0100] As described above, according to the present invention, it is possible to enhance the in-plane uniformity of the main surface of a translucent substrate after peeling a thin film for pattern formation or a thin film having a transferred pattern, and it is possible to contribute to an improvement in the manufacturing yield after recycling. It is possible to manufacture 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.

[0101] In the above-described embodiment, the case where molybdenum is used as the transition metal has been described. However, the same effects as described above can be obtained even in the case of other transition metals. Also, in the above-described embodiment, examples of a phase shift mask blank for manufacturing a display device and a phase shift mask for manufacturing a display device have been described, but the present invention is not limited thereto. The phase shift mask blank and the phase shift mask of the present invention can also be applied to semiconductor device manufacturing, MEMS manufacturing, printed circuit board use, and the like. Further, the application target of the present invention is not limited to the phase shift mask blank and the phase shift mask, and can also be applied to a mask blank and a transfer mask having a thin film containing a metal, silicon, and nitrogen that function as a transmittance adjusting film. Also, in the above-described embodiment, the example where the size of the translucent substrate is 8092 size (800 mm × 920 mm × 10 mm) has been described, but the present invention is not limited thereto. In the case of a phase shift mask blank for manufacturing a display device, a large-sized (Large Size) translucent substrate is used, and the size of the translucent substrate is such that the length of one side is 300 mm or more. The size of the translucent substrate used for 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. In the case of a phase shift mask blank for semiconductor device manufacturing, MEMS manufacturing, or printed circuit board use, a small-sized light-transmissive substrate is used, and the size of the light-transmissive substrate has a side length of 9 inches or less. The size of the light-transmissive substrate used for the phase shift mask blank for the above applications is, for example, 63.1 mm × 63.1 mm or more and 228.6 mm × 228.6 mm or less. Usually, for semiconductor manufacturing and MEMS manufacturing, sizes such as 6025 (152 mm × 152 mm) and 5009 (126.6 mm × 126.6 mm) are used, and for printed circuit board use, sizes such as 7012 (177.4 mm × 177.4 mm) and 9012 (228.6 mm × 228.6 mm) are used.

Explanation of Signs

[0102] 10…Phase shift mask blank (mask blank), 20…Light-transmissive 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 side portion (portion other than the outer peripheral portion), 32…Outer peripheral portion, 30a…Phase shift film pattern (thin film having a transfer pattern), 40…Etching mask film, 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 (mask for transfer),

Claims

1. A mask blank comprising a light-transmissive substrate and a thin film for pattern formation provided on a main surface of the light-transmissive substrate, wherein the thin film contains metal, silicon, and nitrogen, a ratio of a film thickness of the thin film at an outer peripheral portion thereof to a film thickness of the thin film at a portion other than the outer peripheral portion is 0.7 or less, a ratio calculated by dividing a ratio of a nitrogen content to a total content of silicon and metal at the outer peripheral portion of the thin film by a ratio of a nitrogen content to a total content of silicon and metal at a portion other than the outer peripheral portion of the thin film is 0.84 or less. The mask blank is characterized by this.

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

3. The mask blank according to claim 1 or 2, wherein a total content of metal, silicon, and nitrogen of the thin film is 90 atomic % or more.

4. The mask blank according to any one of claims 1 to 3, wherein the thin film contains at least molybdenum.

5. The thin film is a phase shift film, a portion other than the outer peripheral portion of the phase shift film has a transmittance of 3% or more with respect to light having a wavelength of 365 nm and a phase difference with respect to light having a wavelength of 365 nm of 150 degrees or more and 210 degrees or less. The mask blank according to any one of claims 1 to 4 is characterized by this.

6. A transfer mask comprising a light-transmissive substrate and a thin film provided on a main surface of the light-transmissive substrate and having a transfer pattern, wherein the thin film is made of a material containing metal, silicon, and nitrogen, a ratio of a film thickness of the thin film at an outer peripheral portion thereof to a film thickness of the thin film at a portion other than the outer peripheral portion is 0.7 or less, a ratio calculated by dividing a ratio of a nitrogen content to a total content of silicon and metal at the outer peripheral portion of the thin film by a ratio of a nitrogen content to a total content of silicon and metal at a portion other than the outer peripheral portion of the thin film is 0.84 or less. The transfer mask is characterized by this.

7. The transfer mask according to claim 6, wherein an oxygen content of the thin film is 10 atomic % or less.

8. The transfer mask according to claim 6 or 7, wherein a total content of metal, silicon, and nitrogen of the thin film is 90 atomic % or more.

9. The transfer mask according to any one of claims 6 to 8, wherein the thin film contains at least molybdenum.

10. The thin film is a phase shift film, The transfer mask according to any one of claims 6 to 9, wherein a portion other than the outer peripheral portion of the phase shift film has a light transmittance of 3% or more with respect to light having a wavelength of 365 nm and a phase difference with respect to light having a wavelength of 365 nm of 150 degrees or more and 210 degrees or less.

11. A step of peeling the thin film of the mask blank according to any one of claims 1 to 5 or the transfer mask according to any one of claims 6 to 10 using an etching solution containing ammonium hydrogen fluoride and hydrogen peroxide to obtain a light-transmissive substrate from which the thin film has been removed; A step of newly forming a thin film for pattern formation on the main surface of the light-transmissive substrate from which the thin film has been removed; A method for manufacturing a mask blank, characterized by comprising:

12. A method for manufacturing a transfer mask, characterized by comprising a step of forming a pattern by wet etching on the thin film for pattern formation of the mask blank manufactured by the method for manufacturing a mask blank according to claim 11.

13. A step of placing the transfer mask according to any one of claims 6 to 10 on a mask stage of an exposure apparatus; 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, characterized by comprising:

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