Mask blank and method for manufacturing the same, transfer mask and method for manufacturing the same, and method for manufacturing display device

Abstract

The present application provides a mask blank capable of inhibiting deterioration of the shape of the main surface of a light-transmissive substrate after peeling of a film for pattern formation or a film having a transferred pattern, and capable of contributing to improvement of manufacturing yield at the time of recycling. The mask blank includes a light-transmissive substrate, and a film for pattern formation provided on the main surface of the light-transmissive substrate, the film containing metal, silicon, and nitrogen, the film thickness of a peripheral portion of the film being smaller than the film thickness of a portion other than the peripheral portion of the film, and the ratio of the nitrogen content to the silicon content of the peripheral portion of the film being smaller than the ratio of the nitrogen content to the silicon content of the portion other than the peripheral portion of the film.

Description

TECHNICAL FIELD

[0001] The present application relates to a mask blank, a mask for transfer, a method for manufacturing a mask blank, a method for manufacturing a mask for transfer, and a method for manufacturing a display device. BACKGROUND

[0002] In recent years, for display devices such as FPD (Flat Panel Display) typified by LCD (Liquid Crystal Display), not only are large-screen, wide viewing angle being rapidly progressed, but also high definition, high-speed display are being rapidly progressed. In order to achieve the high definition, high-speed display, one of the indispensable elements is to produce fine and high dimensional accuracy electronic circuit patterns such as elements, wiring, etc. The patterning of the electronic circuit for the display device mostly uses photolithography. Therefore, a phase shift mask for display device manufacturing having a fine and high accuracy pattern is required.

[0003] For example, Patent Literature 1 discloses a phase shift mask blank having a light-transmissive substrate, a light semi-transmissive film formed of a metal silicide-based material formed on a main surface of the light-transmissive substrate, and an etching mask film formed of a chromium-based material formed on the light semi-transmissive film, a composition inclined region P is formed at the interface of the light semi-transmissive film and the etching mask film, and in the composition inclined region P, the proportion of the component that slows down the wet etching rate of the light semi-transmissive film is increased stage-wise and / or continuously toward the depth direction.

[0004] These phase shift masks sometimes become unusable due to contamination, damage, etc. caused by repeated use. In addition, sometimes they become unnecessary as the specifications change. On the other hand, in the process of manufacturing the mask blank, mask blanks that do not satisfy the specifications as products are produced at a certain rate. Furthermore, for the phase shift mask produced from the mask blank that satisfies the specifications as products, there are cases where the specifications as the phase shift mask cannot be satisfied. Compared to discarding these phase shift masks, mask blanks, recycling to manufacture mask blanks (recycling) is more effective in terms of reduction of manufacturing cost and resource utilization. In addition, large-sized mask blanks, phase shift masks use large and expensive light-transmissive substrates (glass substrates), and if such light-transmissive substrates can be recycled, particularly significant effects can be obtained.

[0005] Based on this, attempts have been made to remanufacture mask blanks (recycling) using previously used phase-shift masks, mask blanks that do not meet the specifications for products, and phase-shift masks. For example, Patent Document 2 discloses a method for regenerating a mask blank by contacting a glass substrate on which a thin film mainly comprising metal, silicon, and nitrogen is formed on a glass substrate with an aqueous solution to peel off the aforementioned film. The aqueous solution contains at least one fluorinated compound selected from hydrofluoric acid, fluorosilicic acid, and ammonium bifluoride, and at least one oxidant selected from hydrogen peroxide, nitric acid, and sulfuric acid, and contains the aforementioned fluorinated compound in 0.1 to 0.8 wt%.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent 6101646

[0009] Patent Document 2: Japanese Patent Application Publication No. 2010-20339 Summary of the Invention

[0010] The problem that the invention aims to solve

[0011] As described above, when peeling a thin film containing metal, silicon, and nitrogen, contacting it with an aqueous solution containing fluorine compounds and oxidants is suitable. However, the following situation has occurred: the peeling condition of the film differs between the peripheral and central sides. Because the film is contacted with the aforementioned aqueous solution until the entire film peeling is completed, the flatness of the substrate after film peeling deteriorates compared to expectations. Attempts have been made to meet the required flatness and surface roughness of the substrate by performing a given polishing process on the substrate after film peeling. However, for substrates whose shape has deteriorated compared to expectations, the following situation has occurred: even if a given polishing process is performed, the shape of the main surface cannot be sufficiently improved, or even if it can be improved, the desired thickness of the substrate cannot be ensured. This tendency is particularly pronounced for large substrates used in display devices.

[0012] The present invention was made in view of the above-mentioned problems, and aims to provide a mask blank, a transfer mask, a method for manufacturing the mask blank, a method for manufacturing the transfer mask, and a method for manufacturing a display device, which can suppress the shape deterioration of the main surface of the light-transmitting substrate after the thin film for pattern formation or the thin film having the transfer pattern is peeled off.

[0013] Problem Solving Methods

[0014] The present invention provides the following solution as a method for solving the above-mentioned problems.

[0015] (Solution 1) A mask blank comprising: a light-transmitting substrate and a thin film for pattern formation disposed on the main surface of the light-transmitting substrate.

[0016] The aforementioned thin film contains metal, silicon, and nitrogen.

[0017] The film thickness at the outer periphery of the aforementioned film is less than the film thickness of the portion of the aforementioned film excluding the outer periphery.

[0018] The ratio of nitrogen content to silicon content in the outer periphery of the aforementioned thin film is less than the ratio of nitrogen content to silicon content in the portion of the aforementioned thin film excluding the outer periphery.

[0019] (Solution 2) Based on the mask blank described in Solution 1, wherein,

[0020] The ratio of the film thickness of the outer periphery of the aforementioned film to the film thickness of the portion of the aforementioned film excluding the outer periphery is 0.7 or less.

[0021] (Solution 3) Based on the mask blank described in Solution 2, wherein,

[0022] The ratio calculated by dividing the ratio of nitrogen content to silicon content in the outer periphery of the film by the ratio of nitrogen content to silicon content in the portion of the film excluding the outer periphery is 0.84 or less.

[0023] (Scheme 4) The mask blank according to any one of Schemes 1 to 3, wherein,

[0024] The oxygen content of the above-mentioned film is less than 10 atomic%.

[0025] (Scheme 5) The mask blank according to any one of Schemes 1 to 4, wherein,

[0026] The total content of metal, silicon and nitrogen in the above-mentioned thin film is more than 90 atomic%.

[0027] (Solution 6) The mask blank according to any one of Solutions 1 to 5, wherein,

[0028] The aforementioned film contains at least molybdenum.

[0029] (Scheme 7) The mask blank according to any one of Schemes 1 to 6, wherein,

[0030] The above-mentioned thin film is a phase-shifting film.

[0031] The portion of the phase-shifting 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.

[0032] (Solution 8) A transfer mask comprising: a light-transmitting substrate and a thin film having a transfer pattern disposed on the main surface of the light-transmitting substrate.

[0033] The aforementioned thin film is formed from a material containing metal, silicon, and nitrogen.

[0034] The film thickness at the outer periphery of the aforementioned film is less than the film thickness of the portion of the aforementioned film excluding the outer periphery.

[0035] The ratio of nitrogen content to silicon content in the outer periphery of the aforementioned thin film is less than the ratio of nitrogen content to silicon content in the portion of the aforementioned thin film excluding the outer periphery.

[0036] (Solution 9) The transfer mask according to Solution 8, wherein,

[0037] The ratio of the film thickness of the outer periphery of the aforementioned film to the film thickness of the portion of the aforementioned film excluding the outer periphery is 0.7 or less.

[0038] (Solution 10) The transfer mask according to Solution 9, wherein,

[0039] The ratio calculated by dividing the ratio of nitrogen content to silicon content in the outer periphery of the film by the ratio of nitrogen content to silicon content in the portion of the film excluding the outer periphery is 0.84 or less.

[0040] (Solution 11) A transfer mask according to any one of Solutions 8 to 10, wherein,

[0041] The oxygen content of the above-mentioned film is less than 10 atomic%.

[0042] (Scheme 12) A transfer mask according to any one of Schemes 8 to 11, wherein,

[0043] The total content of metal, silicon and nitrogen in the above-mentioned thin film is more than 90 atomic%.

[0044] (Scheme 13) A transfer mask according to any one of Schemes 8 to 12, wherein,

[0045] The aforementioned film contains at least molybdenum.

[0046] (Scheme 14) A transfer mask according to any one of Schemes 8 to 13, wherein,

[0047] The above-mentioned thin film is a phase-shifting film.

[0048] The portion of the phase-shifting 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.

[0049] (Solution 15) A method for manufacturing a mask blank, the method comprising:

[0050] The process of peeling off the film from the mask blank of any one of Schemes 1 to 7, or the transfer mask of any one of Schemes 8 to 14, using an etching solution containing ammonium bifluoride and hydrogen peroxide, to obtain a light-transmitting substrate after the film has been removed; and

[0051] The process of forming a new pattern-forming film on the main surface of a light-transmitting substrate after the aforementioned film has been removed.

[0052] (Solution 16) A method for manufacturing a transfer mask, the method comprising:

[0053] The process of forming a pattern on a thin film for pattern formation of a mask blank manufactured by the mask blank manufacturing method described in Scheme 15 by wet etching.

[0054] (Solution 17) A method for manufacturing a display device, the method comprising:

[0055] The process of placing the transfer mask according to any one of Schemes 8 to 14 onto the mask stage of the exposure apparatus; and

[0056] The process of transferring a transfer pattern onto a resist film disposed on a substrate for a display device by irradiating the aforementioned transfer mask with exposure light.

[0057] The effects of the invention

[0058] According to the present invention, a mask blank, a transfer mask, a method for manufacturing the mask blank, a method for manufacturing the transfer mask, and a method for manufacturing a display device can be provided, which can suppress the shape deterioration of the main surface of the light-transmitting substrate after the pattern-forming film or the film having the transfer pattern is peeled off. Attached Figure Description

[0059] Figure 1 This is a cross-sectional view showing the main part of the mask blank in an embodiment of the present invention.

[0060] Figure 2 This is a graph showing the compositional analysis results in the depth direction of the central side portion (excluding the peripheral portion) of the phase shift mask blank of Example 1.

[0061] Figure 3 This is a graph showing the compositional analysis results in the depth direction of the outer periphery of the phase shift mask blank for Example 1.

[0062] Figure 4This is a schematic diagram showing the film composition of the phase-shifting mask blank (mask blank) in an embodiment of the present invention.

[0063] Figure 5 This is a schematic diagram illustrating the manufacturing process of a phase-shifting mask (transfer mask) according to an embodiment of the present invention.

[0064] Symbol Explanation

[0065] 10…Phase-shifting mask blank (mask blank)

[0066] 20…Transparent substrate

[0067] 21… First primary surface (primary surface)

[0068] 22…Second primary surface (primary surface)

[0069] 23…side view

[0070] 24… Chamfered surface (surface C)

[0071] 30… Phase-shifting film (a thin film for patterning)

[0072] 31…Central side portion (excluding the periphery)

[0073] 32…Peripheral part

[0074] 30a… Phase-shifting film pattern (thin film with transfer pattern)

[0075] 40…Etching mask film

[0076] 40a…First etched mask pattern

[0077] 40b…Second Etched Mask Pattern

[0078] 50… First resist film pattern

[0079] 60…Second resist film pattern

[0080] 100… Phase shift mask (transfer mask) Detailed Implementation

[0081] First, the process of completing this invention will be described. The inventors of this application conducted in-depth research on a solution that could suppress the shape degradation of the main surface of a light-transmitting substrate after peeling off a pattern-forming film (hereinafter sometimes simply referred to as "film") or a film with a transfer pattern, thereby contributing to improved manufacturing yield after recycling. The inventors prepared multiple light-transmitting substrates, formed pattern-forming films on the main surface of each substrate using a sputtering method, and observed their cross-sectional shapes. As a result, in all films, the film thickness at the outer periphery was less than the film thickness of the portion other than the outer periphery (hereinafter sometimes referred to as the "central side portion").

[0082] More specifically, the film thickness is almost uniform in the central portion of the patterned film, but decreases towards the periphery (the side of the transparent substrate). Typically, patterns are formed in the central portion of the film and not in the peripheral portion; therefore, from a transfer performance perspective, the reduced film thickness at the periphery is not a problem. However, it has been found that the difference in film thickness between the peripheral and central portions leads to differences in peeling performance. It is conceivable that making the film thickness consistent between the central and peripheral portions would improve peeling performance. However, this would require significant design changes to the sputtering apparatus, which is impractical.

[0083] Therefore, the inventors changed their thinking and conducted further research on a solution that could improve the peeling condition while allowing for differences in film thickness between the central and peripheral portions. Generally, when forming films containing metal, silicon, and nitrogen, a sputtering target containing metal and silicon is used, and the film formation process is performed in a nitrogen-containing gas atmosphere. Therefore, it is difficult to produce a large difference in the content of metal and silicon between the central and peripheral portions. In order to make the nitrogen content in the peripheral portion different from that in the central portion, the inventors adjusted the nitrogen flow rate and other conditions in the film formation chamber, and formed films with adjusted conditions on multiple prepared substrates. Then, for each film, an aqueous solution containing a fluorine compound and an oxidant was brought into contact with it for peeling, and the shape of the main surface of the substrate after peeling was observed. As a result, it was found that in films formed by reducing the nitrogen flow rate in the peripheral portion compared to the central portion, the degree of shape degradation of the main surface was reduced.

[0084] Further details will be described later, but under the same conditions as the substrate where shape degradation of the main surface was suppressed, a thin film was formed on another substrate, and compositional analysis was performed on the peripheral and central portions. The results showed that the ratio of nitrogen content to silicon content in the peripheral portion was lower than the ratio of nitrogen content to silicon content in the portions other than the peripheral portion.

[0085] The inventors conducted further in-depth research and found that, for thin films containing metal, silicon, and nitrogen, if the film thickness at the outer periphery is less than the film thickness at the portion other than the outer periphery, and the ratio of nitrogen content to silicon content at the outer periphery is less than the ratio of nitrogen content to silicon content at the portion other than the outer periphery, then the shape deterioration of the main surface of the light-transmitting substrate after the film is peeled off can be suppressed, which can help improve the manufacturing yield after recycling.

[0086] This invention is based on the results of the above in-depth research.

[0087] Hereinafter, embodiments of the present invention will be specifically described with reference to the accompanying drawings. It should be noted that the following embodiments are one way of embodying the present invention, and the present invention is not limited to its scope. Furthermore, sometimes the same or equivalent parts in the drawings are labeled with the same symbols, and their descriptions are simplified or omitted.

[0088] Figure 1 This is a cross-sectional view showing the main parts of the mask blank in an embodiment of the present invention. As shown in the figure, the mask blank 10 includes: a light-transmitting substrate 20, and a pattern-forming thin film 30 provided on the main surface 21 of the light-transmitting substrate 20. Hereinafter, each element will be described.

[0089] <Transparent substrate 20>

[0090] The light-transparent substrate 20 (or sometimes simply referred to as substrate 20) is a rectangular plate-like body having two opposing main surfaces 21 and 22, a side surface 23, and a chamfered surface (C-surface) 24. The two opposing main surfaces 21 and 22 are the upper and lower surfaces of the plate-like body, formed in a mutually opposing manner. In addition, at least one of the two opposing main surfaces 21 and 22 is the main surface 21 on which the transfer pattern is to be formed (sometimes referred to as one side of the main surface). In addition, the main surface 22 on the opposite side to the main surface 21 on which the transfer pattern is to be formed is sometimes referred to as the back side (or the other side of the main surface).

[0091] The light-transmitting substrate 20 is transparent to exposure light. Without surface reflection loss, the light-transmitting substrate 20 has a transmittance of 85% or more to exposure light, preferably 90% or more. The light-transmitting substrate 20 is made of a material containing silicon and oxygen, and can be formed from 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 formed from low thermal expansion glass, positional changes in the phase-shift film pattern caused by thermal deformation of the light-transmitting substrate 20 can be suppressed. Furthermore, the light-transmitting substrate 20 used as a phase-shift mask blank in display device applications is typically a rectangular substrate, and a substrate with a short side length of 300 mm or more can be used. The present invention relates to a phase shift mask blank capable of providing a phase shift mask, which can stably transfer fine phase shift film patterns, such as less than 2.0 μm, formed on a light-transmitting substrate 20 even when the short side of the light-transmitting substrate 20 has a length of 300 mm or more.

[0092] <Phase-shifting film (thin film for patterning) 30>

[0093] A phase-shifting film (a thin film for pattern formation) 30 is disposed on the main surface 21 of the light-transmitting substrate 20.

[0094] The phase-shifting film 30 has an outer peripheral portion 32 and a portion other than the outer peripheral portion (central side portion) 31. The film thickness d2 of the outer peripheral portion 32 is less than the film thickness d1 of the central side portion 31. The outer peripheral portion 32 can be defined as the region B within 10 mm from the boundary between the main surface 21 of the light-transmitting substrate 20 and the chamfered surface 24, where the film thickness d2 is less than the film thickness d1 of the central side portion 31. Alternatively, the outer peripheral portion 32 can be defined as the region B within 15 mm from the boundary between the main surface 21 of the light-transmitting substrate 20 and the side surface 23, where the film thickness d2 is less than the film thickness d1 of the central side portion 31.

[0095] The film thickness d1 of the central side portion 31 can be defined as the average film thickness of region A of the central side portion 31.

[0096] The phase-shifting film 30 contains metal, silicon, and nitrogen. The ratio of nitrogen content to silicon content C2(N) / C2(Si) in the outer peripheral portion 32 of the phase-shifting film 30 is less than the ratio of nitrogen content to silicon content C1(N) / C1(Si) in the central side portion 31 of the phase-shifting film 30.

[0097] The phase-shifting film 30 configured in this way can suppress the shape degradation of the main surface 21 of the light-transmitting substrate 20 after the phase-shifting film 30 is peeled off.

[0098] The ratio d2 / d1 of the film thickness d2 of the outer peripheral portion 32 of the phase-shifting film 30 to the film thickness d1 of the central side portion 31 of the phase-shifting film 30 is preferably 0.7 or less. Furthermore, it is preferable that the ratio [C2(N) / C2(Si)] / [C1(N) / C1(Si)], calculated by dividing the ratio C2(N) / C2(Si) of the nitrogen content to silicon content in the outer peripheral portion 32 (within the range where the film thickness ratio d2 / d1 is 0.7 or less) by the ratio C1(N) / C1(Si) of the nitrogen content to silicon content in the central side portion 31 of the phase-shifting film 30, is 0.84 or less. By making the ratio [C2(N) / C2(Si)] / [C1(N) / C1(Si)] of the outer peripheral portion 32 (within the range where the film thickness ratio d2 / d1 is 0.7 or less) 0.84 or less, the shape degradation of the main surface 21 can be further reduced.

[0099] Furthermore, the ratio of the outer peripheral portion 32 [C2(N) / C2(Si)] / [C1(N) / C1(Si)] in the range where the film thickness ratio d2 / d1 is 0.7 or less is more preferably 0.81 or less, and even more preferably 0.77 or less. On the other hand, the ratio of the outer peripheral portion 32 [C2(N) / C2(Si)] / [C1(N) / C1(Si)] in the range where the film thickness ratio d2 / d1 is 0.7 or less is more preferably 0.06 or more, and even more preferably 0.12 or more.

[0100] Furthermore, it is preferable that the ratio [C2(N) / {C2(Si)+C2(M)}] / [C1(N) / {C1(Si)+C1(M)}] calculated by dividing the ratio of nitrogen content in the outer peripheral portion 32 (within the range where the film thickness ratio d2 / d1 is 0.7 or less) to the total content of silicon and metal by C2(N) / {C2(Si)+C1(M)}, the ratio of nitrogen content in the central side portion 31 of the phase-shifting film 30 to the total content of silicon and metal by C1(N) / {C1(Si)+C1(M)}] is 0.84 or less. By making the ratio [C2(N) / {C2(Si)+C2(M)}] / [C1(N) / {C1(Si)+C1(M)}] in the outer peripheral portion 32 (within the range where the film thickness ratio d2 / d1 is 0.7 or less) 0.84 or less, the shape degradation of the main surface 21 can be further reduced.

[0101] Furthermore, the ratio of the outer peripheral portion 32 [C2(N) / {C2(Si)+C2(M)}] / [C1(N) / {C1(Si)+C1(M)}] in the range where the film thickness ratio d2 / d1 is 0.7 or less is preferably 0.81 or less, and more preferably 0.77 or less. On the other hand, the ratio of the outer peripheral portion 32 [C2(N) / {C2(Si)+C2(M)}] / [C1(N) / {C1(Si)+C1(M)}] in the range where the film thickness ratio d2 / d1 is 0.7 or less is preferably 0.06 or more, and more preferably 0.12 or more.

[0102] Furthermore, it is preferable that the ratio [C2(N) / {C2(Si)+C2(M)+C2(O)}] / [C1(N) / {C1(Si)+C1(M)+C2(O)}] calculated by dividing the ratio of nitrogen content in the outer peripheral portion 32 to the total content of silicon, metal and oxygen by C2(N) / {C2(Si)+C2(M)+C2(O)} by the ratio of nitrogen content in the central side portion 31 of the phase-shifting film to the total content of silicon, metal and oxygen by C1(N) / {C1(Si)+C1(M)+C2(O)} is 0.84 or less. By making the ratio of the film thickness d2 / d1 within the range of 0.7 or less, and the ratio of [C2(N) / {C2(Si)+C2(M)+C2(O)}] / [C1(N) / {C1(Si)+C1(M)+C2(O)}] of the outer peripheral portion 32 0.84 or less, it is possible to further reduce the shape degradation of the main surface 21.

[0103] Furthermore, the ratio of the outer peripheral portion 32 [C2(N) / {C2(Si)+C2(M)+C2(O)}] / [C1(N) / {C1(Si)+C1(M)}+C2(O)] in the range where the film thickness ratio d2 / d1 is 0.7 or less is more preferably 0.81 or less, and even more preferably 0.77 or less. On the other hand, the ratio of the outer peripheral portion 32 [C2(N) / {C2(Si)+C2(M)+C2(O)}] / [C1(N) / {C1(Si)+C1(M)+C2(O)}] in the range where the film thickness ratio d2 / d1 is 0.7 or less is more preferably 0.06 or more, and even more preferably 0.12 or more.

[0104] On the other hand, the ratio of the outer peripheral portion 32 with a film thickness ratio d2 / d1 of 0.7, [C2(N) / {C2(Si)] / [C1(N) / {C1(Si)], is preferably 0.56 or more, more preferably 0.59 or less, and even more preferably 0.63 or less. This can further reduce the shape degradation of the main surface 21.

[0105] Furthermore, the ratio of the outer peripheral portion 32 with a film thickness ratio d2 / d1 of 0.7, [C2(N) / {C2(Si)+C2(M)}] / [C1(N) / {C1(Si)+C1(M)}], is preferably 0.56 or more, more preferably 0.59 or less, and even more preferably 0.63 or less. This can further reduce the shape degradation of the main surface 21.

[0106] Furthermore, the ratio of the outer peripheral portion 32 with a film thickness ratio d2 / d1 of 0.7, [C2(N) / {C2(Si)+C2(M)+C2(O)}] / [C1(N) / {C1(Si)+C1(M)+C2(O)}], is preferably 0.56 or more, more preferably 0.59 or less, and even more preferably 0.63 or less. This can further reduce the shape degradation of the main surface 21.

[0107] Transition metals such as molybdenum (Mo), tantalum (Ta), tungsten (W), titanium (Ti), and zirconium (Zr) are suitable as the metals contained in the phase-shifting film 30, and it is preferred that it contains at least molybdenum.

[0108] Preferably, the nitrogen content in the phase-shifting membrane 30 is more than 10 atomic% and less than 50 atomic%. More preferably, it is more than 15 atomic% and less than 45 atomic%.

[0109] The total content of metal, silicon and nitrogen in the phase-shifting film 30 is preferably 90 atomic% or more, and more preferably 92 atomic% or more.

[0110] Furthermore, the ratio of the metal content of the phase-shifting film 30 to the total content of metal and silicon is preferably 0.5 or less, more preferably 0.45 or less, and even more preferably 0.35 or less.

[0111] The phase-shifting membrane 30 may also contain oxygen. The oxygen content in the phase-shifting membrane 30 is preferably 10 atomic% or less, more preferably 8 atomic% or less.

[0112] The phase-shifting film 30 has the function of adjusting the transmittance and phase difference of the exposure light. Preferably, the phase-shifting film 30 further has the function of adjusting the reflectance (hereinafter sometimes referred to as back reflectance) of light incident from the side of the transparent substrate 20.

[0113] The phase-shifting film 30 can be formed by sputtering.

[0114] The transmittance of the portion of the phase-shift film 30 excluding the periphery to the exposure light satisfies the value necessary for the phase-shift film 30. Relative to a given wavelength of light included in the exposure light (hereinafter referred to as the representative wavelength, for example, light with a wavelength of 365 nm), the transmittance of the portion of the phase-shift film 30 excluding the periphery is preferably 3% or more, more preferably 10% or more. Furthermore, relative to the representative wavelength, it is preferably 70% or less, more preferably 65% ​​or less. That is, when the exposure light is a composite light containing light in the wavelength range of 313 nm or more and 436 nm or less, the portion of the phase-shift film 30 excluding the periphery has the aforementioned transmittance relative to the representative wavelength contained in that wavelength range. For example, when the exposure light is a composite light containing the i-line, h-line, and g-line, the portion of the phase-shift film 30 excluding the periphery has the aforementioned transmittance relative to any one of the i-line, h-line, and g-line.

[0115] Transmittance can be measured using devices such as phase shift measurement equipment.

[0116] The phase difference of the portion of the phase shift film 30 excluding the periphery with respect to the exposure light satisfies the value necessary for the phase shift film 30. The phase difference of the portion of the phase shift film 30 excluding the periphery relative to the 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. Utilizing this property, the phase of the representative wavelength contained in the exposure light can be changed within a given phase difference range. Therefore, a given phase difference is generated between the representative wavelength light after passing through the portion of the phase shift film 30 excluding the periphery and the representative wavelength light after passing only through the translucent substrate 20. That is, when the exposure light is a composite light containing light in the wavelength range of 313 nm or more and 436 nm or less, the portion of the phase shift film 30 excluding the periphery has the aforementioned phase difference relative to the representative wavelength contained in that wavelength range. For example, when the exposure light is a composite light including the i-line, h-line and g-line, the portion of the phase shift film 30 excluding the periphery has the aforementioned phase difference relative to any one of the i-line, h-line and g-line.

[0117] Phase difference can be measured using devices such as phase shift measuring instruments.

[0118] Furthermore, the phase-shifting film 30 of the phase-shifting mask blank 10 is required to have high chemical resistance (cleaning resistance). Increasing the film density is effective in improving the chemical resistance (cleaning resistance) of the phase-shifting film 30. The film density of the phase-shifting film 30 is related to the film stress; considering chemical resistance (cleaning resistance), a high film stress is preferred. On the other hand, the film stress of the phase-shifting film 30 needs to take into account positional displacement and loss of the phase-shifting film pattern during its formation. From the above perspectives, the film stress of the phase-shifting film 30 is preferably 0.4 GPa or higher and 0.8 GPa or lower.

[0119] <Etching Mask 40>

[0120] In this embodiment, the phase-shifting mask blank 10 may have an etched mask film 40 (see reference). Figure 4 It should be noted that, in Figure 4 For simplicity, illustrations of the outer periphery and other parts have been omitted. Figure 5 Similarly). The etching mask 40 is disposed above the phase-shifting film 30 and is formed of a material resistant to etching solution used to etch the phase-shifting film 30. Furthermore, the etching mask 40 may have the function of blocking the transmission of exposure light, and further, it may have the function of reducing the reflectivity of the film surface. The etching mask 40 is formed, for example, of a chromium-based material. More specifically, examples of chromium-based materials include: chromium (Cr), or materials containing at least one of chromium (Cr) and oxygen (O), nitrogen (N), and carbon (C). Alternatively, examples include: materials containing at least one of chromium (Cr) and oxygen (O), nitrogen (N), and carbon (C), and further containing fluorine (F). For example, examples of materials constituting the etching mask 40 include: Cr, CrO, CrN, CrF, CrCO, CrCN, CrON, CrCON, and CrCONF.

[0121] The etched mask film 40 can be formed by sputtering.

[0122] When the etching mask 40 has the function of blocking the transmission of exposure light, the optical density relative to the exposure light in the portion where the phase shift film 30 and the etching mask 40 are stacked is preferably 3 or more, more preferably 3.5 or more, and even more preferably 4 or more.

[0123] Optical density can be measured using a spectrophotometer or an OD meter.

[0124] It should be noted that, Figure 1 The phase shift mask blank 10 shown has an etch mask film 40 on the phase shift film 30. The present invention can also be applied to a phase shift mask blank that has an etch mask film 40 on the phase shift film 30 and an etch resist film on the etch mask film 40.

[0125] <Method for manufacturing phase-shifting mask blanks (mask blanks)>

[0126] Next, the manufacturing method of the phase shift mask blank (mask blank) 10 of this embodiment will be described. The phase shift mask blank 10 can be manufactured by performing the following phase shift film formation process and etching mask film formation process.

[0127] The following is a detailed description of each process.

[0128] 1. Phase-shifting film formation process

[0129] First, prepare a light-transmitting substrate 20. The light-transmitting substrate 20 only needs to be transparent to the exposure light, and can be formed from any glass material such as synthetic quartz glass, quartz glass, aluminosilicate glass, soda-lime glass, low thermal expansion glass (SiO2-TiO2 glass, etc.).

[0130] Next, a phase-shifting film 30 is formed on the transparent substrate 20 by sputtering.

[0131] The phase-shifting film 30 is formed using a sputtering target comprising a transition metal and silicon, or a sputtering target comprising a transition metal, silicon, and oxygen and / or nitrogen, which are the main components of the material constituting the phase-shifting film 30. The sputtering gas atmosphere is, for example, a sputtering gas atmosphere composed of at least one inert gas selected from helium, neon, argon, krypton, and xenon, or a sputtering gas atmosphere composed of the aforementioned inert gas and at least one reactive gas selected from oxygen, nitric oxide, and nitrogen dioxide. The film is formed such that the film thickness d2 of the outer peripheral portion 32 of the phase-shifting film 30 is less than the film thickness d1 of the central side portion 31 of the phase-shifting film 30. During this process, the nitrogen flow rate and other conditions in the film-forming chamber are adjusted beforehand so that the nitrogen flow rate is less in the outer peripheral portion 32 than in the central side portion 31 of the phase-shifting film 30. Therefore, the film thickness d2 of the outer peripheral portion 32 of the phase shift film 30 is less than the film thickness d1 of the central side portion 31 of the phase shift film 30, and the ratio of nitrogen content to silicon content C2(N) / C2(Si) of the outer peripheral portion 32 is less than the ratio of nitrogen content to silicon content C1(N) / C1(Si) of the central side portion 31.

[0132] The composition and thickness of the phase-shifting film 30 can be adjusted so that the portion of the phase-shifting film 30 other than the outer periphery achieves the aforementioned phase difference and transmittance. The composition of the phase-shifting film 30 can be controlled by the content ratio of elements constituting the sputtering target (e.g., the ratio of transition metal content to silicon content), the composition of the sputtering gas, and the flow rate. The thickness of the phase-shifting film 30 can be controlled by the sputtering power, sputtering time, etc. Furthermore, in the case of an inline sputtering apparatus, the thickness of the phase-shifting film 30 can be controlled by the substrate transport speed. In this way, the total content of metal, silicon, and nitrogen, and the oxygen content of the phase-shifting film 30 can be controlled to reach a desired range.

[0133] 3. Etching mask film formation process

[0134] After performing surface treatment to adjust the surface oxidation state of the phase shift film 30, an etching mask film 40 is formed on the phase shift film 30 by sputtering.

[0135] Thus, phase shift mask blank 10 can be obtained.

[0136] Using a sputtering target containing chromium or chromium compounds (chromium oxide, chromium nitride, chromium carbide, chromium oxynitride, chromium carbonitride, etc.), the etching of the mask film 40 is performed in a sputtering gas atmosphere. This sputtering gas atmosphere is, for example, a sputtering gas atmosphere composed of at least one inactive gas selected from helium, neon, argon, krypton, and xenon, or a sputtering gas atmosphere composed of a mixture of inactive and active gases. The inactive gas contains at least one selected from helium, neon, argon, krypton, and xenon, and the active gas contains at least one selected from oxygen, nitrogen, nitric oxide, nitrogen dioxide, carbon dioxide, hydrocarbon gases, and fluorine-based gases. Examples of hydrocarbon gases include, for example, methane, butane, propane, and styrene.

[0137] <Phase-shifting mask (transfer mask) and its manufacturing method>

[0138] Figure 5 This is a schematic diagram illustrating the manufacturing process of a phase-shifting mask (transfer mask) according to an embodiment of the present invention.

[0139] Figure 5 The method for manufacturing the phase shift mask shown is to use... Figure 4 The method for manufacturing a phase-shifting mask from the shown phase-shifting mask blank 10. For example... Figure 5As shown in (e), the phase-shift mask 100 has a phase-shift film pattern 30a, which serves as a transfer pattern, formed on the phase-shift film 30 of the mask blank 10, and a second etch mask pattern 40b, which functions as a light-shielding pattern, formed on the etch mask film 40. This phase-shift mask 100 has the same technical features as the mask blank 10. The same applies to matters related to the light-transmitting substrate 20, the central portion 31 of the phase-shift film 30, the outer peripheral portion 32, and the etch mask film 40 in the phase-shift mask 100 as to the mask blank 10. The method for manufacturing a phase-shifting mask includes: a step of forming a resist film on a phase-shifting mask blank 10; a step of forming a resist film pattern 50 by drawing / developing a desired pattern onto the resist film (first resist film patterning step); a step of using the resist film pattern 50 as a mask to pattern an etching mask film 40 by wet etching to form an etching mask film pattern 40a (first etching mask film patterning step); and a step of using the etching mask film pattern 40a as a mask to perform wet etching on a phase-shifting film 30 to form a phase-shifting film pattern 30a on a light-transmitting substrate 20 (phase-shifting film patterning step). Furthermore, it also includes a second resist film patterning step and a second etching mask film patterning step.

[0140] The following is a description of each process.

[0141] 1. First resist film pattern formation process

[0142] In the first resist patterning 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 can be photosensitive to laser light with any wavelength selected from the 350 nm to 436 nm wavelength range is acceptable. Furthermore, the resist film can be either positive or negative.

[0143] Then, a laser with an arbitrary wavelength selected from the range of 350 nm to 436 nm is used to draw the desired pattern on the resist film. The pattern drawn on the resist film is the same pattern formed on the phase shift film 30. Examples of patterns drawn on the resist film include: line and gap patterns, and hole patterns.

[0144] Then, the resist film is developed using the given developer, such as... Figure 5 (a) shows the formation of a first resist pattern 50 on an etched mask film 40.

[0145] 2. First etching mask pattern formation process

[0146] In the first etching mask pattern formation process, the first etching mask 40 is etched using the first resist pattern 50 as a mask to form the first etching mask pattern 40a. The etching mask 40 is formed of a chromium-based material containing chromium (Cr). The etching solution used to etch the etching mask 40 is not particularly limited as long as it can selectively etch the etching mask 40. Specifically, an etching solution containing cerium ammonium nitrate and perchloric acid can be used as an example.

[0147] Then, use a resist stripping solution, or through ashing, such as... Figure 5 (b) The first resist pattern 50 is peeled off as shown. Depending on the circumstances, the following phase-shifting film pattern formation process may be performed without peeling off the first resist pattern 50.

[0148] 3. Phase-shifting film pattern formation process

[0149] In the first phase-shifting film patterning process, the phase-shifting film 30 is etched using the first etching mask film pattern 40a as a mask, as follows: Figure 5 The phase-shifting film pattern 30a is formed as shown in (c). Examples of phase-shifting film patterns 30a include: line and gap patterns, and hole patterns. The etchant used to etch the phase-shifting film 30 is not particularly limited as long as it can selectively etch the phase-shifting film 30. Examples include: etchants containing ammonium fluoride, phosphoric acid, and hydrogen peroxide, and etchants containing ammonium bifluoride and hydrogen chloride.

[0150] 4. Second resist film pattern formation process

[0151] In the second resist patterning step, a resist film covering the first etch mask pattern 40a is first formed. The resist film material used is the same as that used in the first resist patterning step, and there are no particular limitations.

[0152] Then, a laser with any wavelength selected from the range of 350 nm to 436 nm is used to draw the desired pattern on the resist film. The pattern drawn on the resist film is a light-blocking pattern that blocks the light from the outer periphery of the area where the pattern is formed on the phase shift film 30, and a light-blocking pattern that blocks the light from the central portion of the phase shift film pattern. It should be noted that, depending on the transmittance of the phase shift film 30 to the exposure light, the pattern drawn on the resist film also includes a light-blocking pattern that does not block the light from the central portion of the phase shift film pattern 30a.

[0153] Then, the resist film is developed using the given developer, such as... Figure 5 As shown in (d), a second resist film pattern 60 is formed on the first etch mask film pattern 40a.

[0154] 5. Second etching mask pattern formation process

[0155] In the second etching mask pattern formation process, the first etching mask pattern 40a is etched using the second resist pattern 60 as a mask, as shown below. Figure 2 (e) shows the formation of the second etch mask pattern 40b. The first etch mask pattern 40a is formed from a chromium-containing (Cr) material. The etchant used to etch the first etch mask pattern 40a is not particularly limited as long as it can selectively etch the first etch mask pattern 40a. Examples include etchants containing cerium ammonium nitrate and perchloric acid.

[0156] Then, the second resist pattern 60 is peeled off using a resist stripping solution or by ashing.

[0157] Thus, phase shift mask 100 can be obtained.

[0158] It should be noted that in the above description, 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 only has the function of a hard mask when etching the phase shift film 30, in the above description, the second resist film pattern forming process and the second etching mask film pattern forming process are not performed. Instead, the first etching mask film pattern is peeled off after the phase shift film pattern forming process to produce the phase shift mask 100.

[0159] According to the manufacturing method of this phase shift mask, since the phase shift mask blank of Embodiment 1 is used, a phase shift film pattern with good cross-sectional shape and small CD deviation can be formed. Therefore, a phase shift mask capable of transferring high-precision phase shift film patterns with good accuracy can be manufactured. The phase shift mask manufactured in this way can cope with the miniaturization of line and gap patterns and contact holes.

[0160]

[0161] Next, the method of recycling the aforementioned 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.

[0162] First, a phase shift mask blank 10 or a phase shift mask 100 that is to be recycled is prepared. The components of the phase shift mask blank 10 or the phase shift mask 100 that is to be recycled are described above.

[0163] Next, a process is performed to remove the etched mask film 40 in the phase shift mask blank 10 or the etched mask film pattern 40b in the phase shift mask 100 using a stripping solution. In the case where it is formed of a chromium-based material, the removal of the etched mask film 40 or the etched mask film pattern 40b can be performed by etching the etched mask film 40 or the etched mask film pattern 40b with a chromium etchant consisting of pure water containing cerium ammonium nitrate ((NH4)2Ce(NO3)6) and perchloric acid (HClO4).

[0164] Then, a step is performed to remove the phase-shifting film (thin film) 30 in the phase-shifting mask blank 10 or the phase-shifting film pattern (thin film with transfer pattern) 30a in the phase-shifting mask 100 using a stripping solution. The removal of the phase-shifting film 30 or the phase-shifting film pattern 30a can be performed using an etching solution containing ammonium bifluoride and hydrogen peroxide. Preferably, the etching solution is an aqueous solution containing at least one fluorinated compound selected from hydrofluoric acid, fluorosilicic acid, and ammonium bifluoride, and at least one oxidant selected from hydrogen peroxide, nitric acid, and sulfuric acid, and containing the fluorinated compound in 0.1 to 0.8 wt% and the oxidant in 0.5 to 4.0 wt%, and the above removal is performed by contacting the aqueous solution.

[0165] As described above, the film thickness d2 of the outer peripheral portion 32 of the phase-shifting film 30 or the phase-shifting film pattern 30a is less than the film thickness d1 of the central side portion 31 of the phase-shifting film 30 or the phase-shifting film pattern 30a, and the ratio of nitrogen content to silicon content C2(N) / C2(Si) of the outer peripheral portion 32 is less than the ratio of nitrogen content to silicon content C1(N) / C1(Si) of the central side portion 31. Therefore, when the phase-shifting film 30 or the phase-shifting film pattern 30a is processed using the aforementioned etching solution, the etching rate of the outer peripheral portion 32 can be suppressed compared to the etching rate of the central side portion 31. This significantly reduces the difference between the time required to remove the outer peripheral portion 32, which has a smaller thickness than the central side portion 31, and the time required to remove the central side portion 31. This improves the in-plane uniformity of the main surface 21 of the transparent substrate 20 after the phase-shifting film 30 or the phase-shifting film pattern 30a has been peeled off. In this way, a transparent substrate after the phase-shifting film 30 or the phase-shifting film pattern 30a has been removed can be obtained.

[0166] The main surfaces 21 and 22 of the transparent substrate 20 after the phase-shift film 30 or the phase-shift film pattern 30a has been peeled off are measured using an inspection device (flatness measurement). Then, a given grinding and cleaning process is performed appropriately based on the inspection results. Next, an evaluation process is conducted on the transparent substrate 20 to determine whether it meets the quality requirements for a recycled substrate (flatness of the main surface 21 and thickness of the transparent substrate 20, etc.). For transparent substrates 20 that are deemed to meet the requirements, a process is performed to form a new thin film for pattern formation. This allows the manufacture of a new mask blank. When the new mask blank is used as the phase-shift mask blank 10, the process of forming the new thin film for pattern formation is performed in the same manner as described in the above-described method for manufacturing a phase-shift mask blank (mask blank). It should be noted that the new mask blank does not necessarily have to be the phase-shift mask blank 10; it can also be, for example, a mask blank for binary applications.

[0167]

[0168] A method for manufacturing a new transfer mask using a mask blank manufactured by the aforementioned new mask blank manufacturing method will be described. The method for manufacturing this new transfer mask includes a process of forming a pattern on a pattern-forming thin film of the newly manufactured mask blank by wet etching. When the newly manufactured mask blank is a phase-shift mask blank 10, the phase-shift film pattern 30a on the pattern-forming thin film (phase-shift film) 30 of the mask blank 10 can be formed by wet etching, as described in the above-described "Phase-Shift Mask (Transfer Mask) and its Manufacturing Method". It should be noted that, similarly, when the new mask blank is, for example, a mask blank for binary applications, a pattern can also be formed by wet etching of the pattern-forming thin film (e.g., an etching mask film of a chromium-based material with light-shielding properties) formed on the light-transmitting substrate 20 using an etching solution containing cerium ammonium nitrate and perchloric acid.

[0169] <Manufacturing Method of Display Device>

[0170] The display device is manufactured by performing a process of using the aforementioned transfer mask (mask placement process) and a process of exposing and transferring the transfer pattern onto the resist film on the display device (pattern transfer process).

[0171] The following is a detailed description of each process.

[0172] 1. Loading process

[0173] In the placement process, the transfer mask is placed on the mask stage of the exposure apparatus. Here, the transfer mask can be any mask among the phase shift mask (transfer mask) 100 manufactured using the phase shift mask blank 10 and the new transfer mask manufactured by the above-described new transfer mask manufacturing method. The transfer mask is arranged in a manner that separates it from the projection optics system of the exposure apparatus and faces the resist film formed on the display device substrate.

[0174] 2. Pattern transfer process

[0175] In the pattern transfer process, an exposure light is irradiated onto a transfer mask to transfer the phase-shift film pattern onto a resist film formed on the display device substrate. The exposure light can be a composite light containing multiple wavelengths selected from the 365nm to 436nm wavelength range, or monochromatic light selected by removing a specific wavelength range from the 365nm to 436nm wavelength range using a filter. For example, the exposure light can be a composite light containing i-lines, h-lines, and g-lines, or i-line monochromatic light. Using composite light as the exposure light can increase the intensity of the exposure light and thus increase the luminous flux, thereby reducing the manufacturing cost of the display device.

[0176] According to the manufacturing method of this display device, a high-precision display device capable of suppressing CD errors, high resolution, having fine line and gap patterns, and contact holes can be manufactured.

[0177] Example

[0178] Example 1.

[0179] A. Phase shift mask blanks and their manufacturing methods

[0180] In order to manufacture the phase shift mask blank of Example 1, a synthetic quartz glass substrate with a size of 1214 (1220mm × 1400mm) was first prepared as a light-transmitting substrate 20.

[0181] Then, the synthetic quartz glass substrate is placed on a tray (not shown) with the main surface facing downwards and conveyed into the chamber of the inline sputtering apparatus.

[0182] To form a phase-shifting film 30 on the main surface 21 of the transparent substrate 20, firstly, a mixture of argon (Ar), oxygen (O2), and nitrogen (N2) gas is introduced into the first chamber at a given vacuum level. Then, reactive sputtering is performed using a first sputtering target containing molybdenum and silicon (molybdenum:silicon = 1:4) to deposit molybdenum silicide oxynitride containing molybdenum, silicon, oxygen, and nitrogen onto the main surface of the transparent substrate 20. During this process, the nitrogen flow rate in the deposition chamber and the configuration of the gas inlet and outlet are adjusted to ensure that the amount of nitrogen in the chamber is less at the outer periphery 32 than at the central side 31. Next, a phase-shifting film 30 with a thickness d1 of 110 nm is formed in the central side 31. Twenty-five measurement points (five vertical and five horizontal) are set within a 30 mm rectangular area of ​​the central side 31, and the film thickness d1 is calculated as the average thickness at each measurement point. In addition, in region B of the outer periphery 32, the film thickness d2 is always less than the film thickness d1.

[0183] Region B of the outer periphery 32 is formed on the main surface 21 of the light-transmitting substrate 20 within a range of 4 mm to 7 mm from the boundary of the chamfered surface 24, and is a region within 10 mm from the boundary of the chamfered surface 24 of the main surface 21.

[0184] Next, the transparent substrate 20 with phase-shifting film 30 is placed into the second chamber. With the second chamber set to a given vacuum level, a mixture of argon (Ar) and nitrogen (N2) is introduced. Then, using reactive sputtering with a second sputtering target formed of chromium, a chromium nitride (CrN) containing chromium and nitrogen (15 nm thick) is formed on the phase-shifting film 30. Next, with the third chamber set to a given vacuum level, a mixture of argon (Ar) and methane (CH4) is introduced. Using a third sputtering target formed of chromium, a chromium carbide (CrC) containing chromium and carbon (60 nm thick) is formed on the CrN using reactive sputtering. Finally, with the fourth chamber set to a given vacuum level, a mixture of argon (Ar) and methane (CH4) and a mixture of nitrogen (N2) and oxygen (O2) (Ar+CH4) were introduced. Chromium carbonitride (CrCON) containing chromium, carbon, oxygen, and nitrogen (film thickness 30 nm) was formed on CrC using reactive sputtering on a fourth sputtering target formed of chromium. As described above, an etching mask film 40 with a stacked structure of CrN, CrC, and CrCON layers was formed on the phase-shifting film 30.

[0185] In this way, a phase shift mask blank 10 is obtained, on which a phase shift film 30 and an etching mask film 40 are formed on a light-transmitting substrate 20.

[0186] For the phase-shifting film 30 of the obtained phase-shifting mask blank 10, the transmittance and phase difference of the central side portion 31 were measured using an MPM-100 manufactured by Lasertec. The transmittance and phase difference of the phase-shifting film 30 were measured using a substrate (model substrate) with the phase-shifting film 30 deposited on the main surface of a synthetic quartz glass substrate, which was mounted on the same tray. The substrate (model substrate) with the phase-shifting film was removed from the chamber before forming the etching mask film 40, and the transmittance and phase difference of the phase-shifting film 30 were measured. The results showed a transmittance of 5.2% (wavelength: 365 nm) and a phase difference of 176 degrees (wavelength: 365 nm).

[0187] Under the above conditions, a phase-shifting film and an etch mask film were formed relative to another transparent substrate. Then, the outer peripheral and central portions of the phase-shifting film were subjected to depth-direction composition analysis based on X-ray photoelectron spectroscopy (XPS). Figure 3 This is a graph showing the compositional analysis results in the depth direction of the central side portion (excluding the peripheral portion) of the phase-shifting mask blank of Example 1. Additionally, Figure 2 This is a graph showing the compositional analysis results of the outer periphery of the phase-shift mask blank in the depth direction for Example 1. Here, in Figure 2 In the middle section 31, the compositional analysis results are shown at the location where the measured film thickness d1 reaches approximately the same thickness as the average film thickness. Therefore, it can be considered that... Figure 3 The compositional analysis results shown reveal the average characteristics of the central portion 31 as a whole. Furthermore, in Figure 2 In the diagram, the compositional analysis results at the location where the measured film thickness d2 is 77 nm are shown in the outer peripheral portion 32. That is, the film thickness ratio d2 / d1 is 0.7.

[0188] Figure 3 , Figure 3 The horizontal axis represents the grinding time (in minutes) of the phase-shifting mask blank 10 relative to the outermost surface of the etched mask film 40, and the vertical axis represents the content (atomic %). Figure 2 In the figure, each curve represents the change in the content of silicon (Si), nitrogen (N), oxygen (O), chromium (Cr), and molybdenum (Mo).

[0189] like Figure 3 and Figure 2As shown, in the XPS-based depth-direction composition analysis of the phase-shift mask blank 10, in the region of the phase-shift film 30 between the interface between the phase-shift film 30 and the etching mask film 40 (where the proportion of transition metal decreases from the phase-shift film 30 to the etching mask film 40 and the content of transition metal reaches 0 atomic% for the first time) and the interface between the phase-shift film 30 and the transparent substrate 20 (where the proportion of transition metal decreases from the phase-shift film 30 to the transparent substrate 20 and the content of transition metal reaches 0 atomic% for the first time), the nitrogen content of the outer peripheral portion 32 is less than that of the central portion (excluding the outer peripheral portion) 31. Furthermore, it is also known that, similarly, in both the outer peripheral portion 32 and the central portion 31, the oxygen content is less than 10 atomic%, and the combined content of metal, silicon, and nitrogen is more than 90 atomic%.

[0190] according to Figure 3 The results, calculated as average values ​​of each component in the central portion 31 of the phase-shifting film 30, show that the silicon content (C1(Si)) is 41.3 atoms, the molybdenum content (C1(Mo)) is 16.3 atoms, the nitrogen content (C1(N)) is 35.6 atoms, the oxygen content (C1(O)) is 5.4 atoms, the carbon content (C1(C)) is 1.1 atoms, and the chromium content (C1(Cr)) is 0.3 atoms.

[0191] In addition, according to Figure 5 The results, calculated from the average values ​​of the components of the outer periphery 32 of the phase-shifting film 30 (the position where the film thickness ratio d2 / d1 is 0.7), show that the silicon content (C2(Si)) is 48.7 atoms, the molybdenum content (C2(Mo)) is 20.1 atoms, the nitrogen content (C2(N)) is 29.1 atoms, the oxygen content (C2(O)) is 1.0 atoms, the carbon content (C2(C)) is 0.9 atoms, and the chromium content (C2(Cr)) is 0.2 atoms.

[0192] Based on these results, the ratios C1(N) / C1(Si) of the central portion (excluding the peripheral portion) 31 are 0.862, C1(N) / {C1(Si)+C1(Mo)} is 0.618, and C1(N) / {C1(Si)+C1(Mo)+C1(O)} is 0.565. Furthermore, the ratios C2(N) / C2(Si) of the peripheral portion 32 are 0.598, C2(N) / {C2(Si)+C2(Mo)} is 0.423, and C2(N) / {C2(Si)+C2(Mo)+C2(O)} is 0.417. That is, for all the aforementioned ratios, the peripheral portion 32 has lower ratios than the central portion 31.

[0193] Furthermore, it can be seen that the ratio [C2(N) / C2(Si)] / [C1(N) / C1(Si)] is 0.694, the ratio [C2(N) / {C2(Si)+C2(M)}] / [C1(N) / {C1(Si)+C1(M)}] is 0.685, and the ratio [C2(N) / {C2(Si)+C2(M)+C2(O)}] / [C1(N) / {C1(Si)+C1(M)+C2(O)}] is 0.738. All of the above ratios are below 0.84.

[0194] B. Phase-shifting masks and their manufacturing methods

[0195] For the phase shift mask blank 10 manufactured as described above, according to Figure 2 In the sequence shown, a phase shift mask 100 is obtained in which a phase shift film pattern 30a is formed in the transfer pattern forming area on the light-transmitting substrate 20, and a light-shielding pattern is formed by a stacked structure of the phase shift film pattern 30a and the etch mask film pattern 40b.

[0196] The CD deviation of the phase shift film pattern of the phase shift mask was measured using a SIR8000 manufactured by Seiko Instruments Nanotechnology Co., Ltd., and the results showed that the CD deviation was good.

[0197] C. Manufacturing method of display device

[0198] Therefore, it can be considered that when the phase-shifting mask of this embodiment 1 is placed on the mask stage of the exposure device and the resist film transferred to the display device is exposed, fine patterns can be transferred with high precision.

[0199] D. A new method for manufacturing mask blanks

[0200] Ten phase shift mask blanks 10 or phase shift masks 100 from Example 1 were prepared respectively, and the following process was performed on each etching mask film 40 or etching mask film pattern 40b: a process of removing the etch mask film 40 or etching mask film pattern 40b by supplying a chromium etching solution composed of pure water containing cerium ammonium nitrate ((NH4)2Ce(NO3)6) and perchloric acid (HClO4).

[0201] Then, a step is performed to remove the phase shift film (thin film) 30 in the phase shift mask blank 10 or the phase shift film pattern (thin film with transfer pattern) 30a in the phase shift mask 100 using a stripping solution. In this step, a mixed aqueous solution of ammonium bifluoride (0.5 wt%), hydrogen peroxide (2.0 wt%), and pure water (97.5 wt%) is used as the aqueous solution.

[0202] Next, using an inspection device, the main surfaces 21 and 22 of the substrate 20 after the phase-shift film (thin film) 30 or the phase-shift film pattern (thin film with transfer pattern) 30a were removed were inspected for surface shape, in-plane uniformity, etc. For any substrate 20, in-plane uniformity was within the allowable range, and good results were obtained.

[0203] Then, using a polishing slurry containing known free abrasive particles such as cerium oxide and colloidal silica, and a polishing pad, the main surfaces 21 and 22 of the substrate 20 were appropriately polished and cleaned.

[0204] Then, an evaluation process was performed on the light-transmitting substrate 20 to determine whether it met the quality requirements for a recyclable substrate. As a result, the quality requirements were met for any substrate 20.

[0205] Then, as described in <A. Phase shift mask blank and manufacturing method thereof>, <B. Phase shift mask and manufacturing method thereof>, and <C. Manufacturing method of display device> in Example 1, new phase shift mask blanks, phase shift masks, and display devices were manufactured, and good results were obtained in all cases.

[0206] As described above, according to this embodiment, a mask blank, a transfer mask, a method for manufacturing the mask blank, a method for manufacturing the transfer mask, and a method for manufacturing a display device can be provided that can improve the in-plane uniformity of the main surface of the light-transmitting substrate after peeling off the thin film for pattern forming or the thin film having the transfer pattern, and can help improve the manufacturing yield after recycling.

[0207] Comparative Example 1.

[0208] In order to manufacture the phase shift mask blank 10 of Comparative Example 1, a synthetic quartz glass substrate with a size of 1214 (1220mm × 1400mm) was prepared as a light-transmitting substrate 20, in the same manner as in Example 1.

[0209] A synthetic quartz glass substrate was placed into the chamber of an inline sputtering apparatus. In Comparative Example 1, unlike Example 1, the phase-shifted film 30 was formed without setting conditions such as the flow rate of nitrogen in the film-forming chamber. The same sputtering target materials as in Example 1 were used as the first, second, third, and fourth sputtering targets.

[0210] Then, the etching mask film 40 was formed using the same method as in Example 1.

[0211] Thus, a phase shift mask blank 10 having a phase shift film 30 and an etching mask film 40 formed on a light-transmitting substrate 20 is obtained.

[0212] The transmittance and phase difference of the phase-shifting film 30 (after the surface of the phase-shifting film was washed with pure water) of the obtained phase-shifting mask blank 10 were measured using an MPM-100 manufactured by Lasertec. In the measurement of the transmittance and phase difference of the phase-shifting film, a substrate (model substrate) with the phase-shifting film 30 formed on the main surface of a synthetic quartz glass substrate and mounted on the same tray was used. The substrate (model substrate) with the phase-shifting film was removed from the chamber before forming the etching mask film, and the transmittance and phase difference of the phase-shifting film 30 were measured. The results showed a transmittance of 5.2% (wavelength: 365 nm) and a phase difference of 176 degrees (wavelength: 365 nm).

[0213] In addition, under the same conditions as Comparative Example 1, a phase-shifting film and an etch mask film were formed on a different transparent substrate. Then, a depth-direction compositional analysis based on X-ray photoelectron spectroscopy (XPS) was performed on the outer periphery and central portion of the phase-shifting film. The compositional analysis results of the central portion of the phase-shifting film are consistent with... ​ The results of Example 1 shown are equivalent. On the other hand, the compositional analysis results of the outer periphery of the phase-shifting film are equivalent to the compositional analysis results of the central side of the phase-shifting film. That is, the ratio of nitrogen content to silicon content C1(N) / C1(Si) in the central side (excluding the outer periphery) has the same value as the ratio of nitrogen content to silicon content C2(N) / C2(Si) in the outer periphery.

[0214] Similarly, the ratio C1(N) / {C1(Si)+C1(Mo)} has the same value as the ratio C2(N) / {C2(Si)+C2(Mo)}, and the ratio C1(N) / {C1(Si)+C1(Mo)+C1(O)} has the same value as the ratio C2(N) / {C2(Si)+C2(Mo)+C2(O)}. Therefore, the ratios [C2(N) / C2(Si)] / [C1(N) / C1(Si)], [C2(N) / {C2(Si)+C2(M)}] / [C1(N) / {C1(Si)+C1(M)}], and [C2(N) / {C2(Si)+C2(M)+C2(O)}] / [C1(N) / {C1(Si)+C1(M)+C2(O)}] are all less than 1 and far exceed 0.84.

[0215] Furthermore, for the phase-shifting membrane, the flatness change was measured and the membrane stress was calculated using UltraFLAT 200M (manufactured by Corning TROPEL), with a result of 0.46 GPa. This phase-shifting membrane 30 exhibits small changes in transmittance and phase difference with respect to the chemical solutions used in cleaning the phase-shifting mask (sulfuric acid / hydrogen peroxide mixture, ammonia / hydrogen peroxide mixture, and ozone water), demonstrating high chemical resistance and cleaning resistance.

[0216] B. Phase-shifting masks and their manufacturing methods

[0217] A phase shift mask was manufactured using the same method as in Example 1, using the phase shift mask blank manufactured as described above.

[0218] The CD deviation of the phase shift film pattern of the phase shift mask was measured using a SIR8000 manufactured by Seiko Instruments Nanotechnology Co., Ltd., and the results showed that the CD deviation was good.

[0219] C. Manufacturing method of display device

[0220] Therefore, when the phase-shift mask of Comparative Example 1 is placed on the mask stage of the exposure apparatus and the resist film transferred to the display device is exposed, fine patterns can be transferred with high precision.

[0221] D. A new method for manufacturing mask blanks

[0222] Ten phase shift mask blanks 10 or phase shift masks 100 from Comparative Example 1 were prepared respectively, and the following process was performed on each etching mask film 40 or etching mask film pattern 40b: a process of removing the mask film 40 or etching mask film pattern 40b by supplying a chromium etching solution composed of pure water containing cerium ammonium nitrate ((NH4)2Ce(NO3)6) and perchloric acid (HClO4).

[0223] Then, a step is performed to remove the phase shift film (thin film) 30 in the phase shift mask blank 10 or the phase shift film pattern (thin film with transfer pattern) 30a in the phase shift mask 100 using a stripping solution. In this step, a mixed aqueous solution of ammonium bifluoride (0.5 wt%), hydrogen peroxide (2.0 wt%), and pure water (97.5 wt%) is used as the aqueous solution.

[0224] Next, using a polishing slurry containing known free abrasive particles such as cerium oxide and colloidal silica, and a polishing pad, appropriate polishing and cleaning processes were performed on the main surfaces 21 and 22 of the substrate 20 after the phase-shift film (thin film) 30 or the phase-shift film pattern (thin film with transfer pattern) 30a was removed. For all substrates 20, more polishing processes and a larger amount of polishing were required than those in Example 1.

[0225] Then, the surface shape (flatness, etc.) and thickness of the light-transmitting substrate 20 were measured using an inspection device. Based on these results, an evaluation process was conducted to determine whether the substrate met the quality requirements for recycling. The results showed that 5 substrates 20 did not meet the necessary thickness standards and were therefore deemed unqualified. That is, out of the initially prepared 10 substrates 20, only 5 were determined to meet the quality requirements.

[0226] Then, as described in Comparative Example 1, in <A. Phase Shift Mask Blank and Manufacturing Method Thereof>, <B. Phase Shift Mask and Manufacturing Method Thereof>, and <C. Manufacturing Method of Display Device>, new phase shift mask blanks, phase shift masks, and display devices were manufactured. As a result, the performance was either equal to or lower than that of the phase shift mask in Comparative Example 1 before recycling. Consequently, subsequent recycling was not possible.

[0227] As described above, according to the present invention, it is possible to manufacture a mask blank capable of improving the in-plane uniformity of the main surface of a light-transmitting substrate after peeling off a thin film for pattern formation or a thin film having a transfer pattern, and capable of improving the manufacturing yield after recycling; 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.

[0228] It should be noted that the above embodiments describe the use of molybdenum as a transition metal, but the same effect can be obtained with other transition metals.

[0229] Furthermore, while examples of phase-shift mask blanks and phase-shift masks for display device manufacturing have been described in the above embodiments, they are not limited thereto. The phase-shift mask blanks and phase-shift masks of the present invention are also applicable to semiconductor device manufacturing, MEMS manufacturing, printed circuit board applications, etc. Moreover, the scope of application of the present invention is not limited to phase-shift mask blanks and phase-shift masks; it can also be applied to mask blanks containing thin films of metal, silicon, and nitrogen that function as transmittance adjustment films, transfer masks, etc.

[0230] Furthermore, in the above embodiments, an example of a transparent substrate with dimensions of 8092 (800mm × 920mm × 10mm) was described, but it is not a limitation. In the case of a phase-shift mask blank for display device manufacturing, a large-size transparent substrate can be used, with dimensions of 300mm or more on one side. The dimensions of the transparent substrate used for a phase-shift mask blank for display device manufacturing are, for example, 330mm × 450mm or more and 2280mm × 3130mm or less.

[0231] Furthermore, in the case of phase shift mask blanks for semiconductor device manufacturing, MEMS manufacturing, and printed circuit board applications, small-size transparent substrates are used, with a side length of 9 inches or less. The dimensions of the transparent substrates for phase shift mask blanks used in these applications are, for example, 63.1mm × 63.1mm or larger and 228.6mm × 228.6mm or smaller. Typically, 6025 (152mm × 152mm) and 5009 (126.6mm × 126.6mm) sizes are used for semiconductor and MEMS manufacturing applications, while 7012 (177.4mm × 177.4mm) and 9012 (228.6mm × 228.6mm) sizes are used for printed circuit board applications.

Claims

1. A mask blank, comprising: Transparent substrate, and A thin film for pattern formation disposed on the main surface of the light-transmitting substrate. in, The thin film contains metal, silicon, and nitrogen. The film thickness at the outer periphery of the film is less than the film thickness of the portion of the film excluding the outer periphery. The ratio of nitrogen content to silicon content in the outer periphery of the film is less than the ratio of nitrogen content to silicon content in the portion of the film excluding the outer periphery. The ratio of the film thickness at the outer periphery of the film to the film thickness of the portion of the film excluding the outer periphery is 0.7 or less. The ratio calculated by dividing the ratio of nitrogen content to silicon content in the outer periphery of the film by the ratio of nitrogen content to silicon content in the portion of the film excluding the outer periphery is 0.84 or less.

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

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

4. The mask blank according to claim 1 or 2, wherein, The film contains at least molybdenum.

5. The mask blank according to claim 1 or 2, wherein, The thin film is a phase-shifting film. The portion of the phase-shifting film other than the outer periphery 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.

6. A transfer mask, comprising: Transparent substrate, and A thin film having a transfer pattern is disposed on the main surface of the light-transmitting substrate. in, The thin film is formed from a material containing metal, silicon, and nitrogen. The film thickness at the outer periphery of the film is less than the film thickness of the portion of the film excluding the outer periphery. The ratio of nitrogen content to silicon content in the outer periphery of the film is less than the ratio of nitrogen content to silicon content in the portion of the film excluding the outer periphery. The ratio of the film thickness at the outer periphery of the film to the film thickness of the portion of the film excluding the outer periphery is 0.7 or less. The ratio calculated by dividing the ratio of nitrogen content to silicon content in the outer periphery of the film by the ratio of nitrogen content to silicon content in the portion of the film excluding the outer periphery is 0.84 or less.

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

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

9. The transfer mask according to claim 6 or 7, wherein, The film contains at least molybdenum.

10. The transfer mask according to claim 6 or 7, wherein, The thin film is a phase-shifting film. The portion of the phase-shifting film other than the outer periphery 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.

11. A method for manufacturing a mask blank, the method comprising: The process of peeling off the film from the mask blank of any one of claims 1 to 5 or the transfer mask of any one of claims 6 to 10 using an etching solution containing ammonium bifluoride and hydrogen peroxide to obtain a light-transmitting substrate after the film has been removed. and The process of forming a new pattern-forming film on the main surface of a light-transmitting substrate after the original film has been removed.

12. A method for manufacturing a transfer mask, the method comprising: The process of forming a patterned thin film of a mask blank manufactured by the mask blank manufacturing method of claim 11 by wet etching.

13. A method for manufacturing a display device, the method comprising: The process of placing the transfer mask according to any one of claims 6 to 10 onto the mask stage of the exposure apparatus; and The process of transferring a transfer pattern onto a resist film disposed on a substrate for a display device by irradiating the transfer mask with exposure light.

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