Photomask blank, method for manufacturing photomask blank, method for manufacturing photomask, and method for manufacturing display device

Abstract

The present invention provides a photomask blank, which can shorten the overetching time when forming a transfer pattern by wet etching a pattern-forming film, and can form a transfer pattern having a good cross-sectional shape, satisfying the cleaning resistance required in the pattern-forming film or the transfer pattern, and satisfying the required line edge roughness. The photomask blank has a pattern-forming film on a transparent substrate, wherein the photomask blank is an original plate for forming a photomask, the photomask has a transfer pattern on the transparent substrate by wet etching the pattern-forming film, the pattern-forming film contains a transition metal and silicon, the pattern-forming film has a columnar structure, and includes an upper layer and a lower layer, and the average size of particles constituting the columnar structure in the upper layer is smaller than the average size of particles constituting the columnar structure in the lower layer.

Description

Technical Field

[0001] The present invention relates to a photomask blank, a method for manufacturing the photomask blank, a method for manufacturing a photomask, and a display device. Background Art

[0002] In recent years, for display devices such as FPD (Flat Panel Display) represented by LCD (Liquid Crystal Display), not only are large screens and wide viewing angles being rapidly developed, but also high-definition and high-speed display are being rapidly developed. In order to achieve this high-definition and high-speed display, one of the necessary elements is to manufacture electronic circuit patterns such as components and wiring that are fine and have high dimensional accuracy. The patterning of electronic circuits for the display device mostly uses photolithography. Therefore, it is necessary to form a photomask such as a phase shift mask and a binary mask for the manufacture of a display device with a fine and high-precision pattern.

[0003] For example, Patent Document 1 discloses a phase reversal mask blank having a phase reversal film on a transparent substrate. In the mask blank, the phase reversal film is composed of a multilayer film of two or more layers formed of a metal silicide compound containing at least one light element substance among oxygen (O), nitrogen (N), and carbon (C), and is made to have a reflectivity of 35% or less and a transmittance of 1% to 40% for exposure light of a composite wavelength containing i-line (365nm), h-line (405nm), and g-line (436nm), and a gradient of a pattern cross section is formed sharply when forming a pattern, and the metal silicide compound is formed by injecting a reactive gas containing the above light element substance and an inactive gas at a ratio of 0.5:9.5 to 4:6.

[0004] In addition, Patent Document 2 discloses a phase shift mask blank, which includes a transparent substrate, a light semi-transmissive film, and an etching mask film, wherein the light semi-transmissive film has the property of changing the phase of exposure light and is composed of a metal silicide material, and the etching mask film is composed of a chromium-based material. In the phase shift mask blank, a composition gradient region is formed at the interface between the light semi-transmissive film and the etching mask film. In the composition gradient region, the proportion of a component that slows down the wet etching speed of the light semi-transmissive film increases in the depth direction. Moreover, the oxygen content in the composition gradient region is less than 10 atomic %.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Korean Patent No. 1801101

[0008] Patent Document 2: Japanese Patent No. 6101646 Summary of the invention

[0009] Problems to be solved by the invention

[0010] In recent years, phase shift masks used in the production of high-definition (1000 ppi or more) panels have been required to have fine phase shift film patterns with an aperture of 6 μm or less and a line width of 4 μm or less in order to transfer high-resolution patterns. Specifically, phase shift masks with fine phase shift film patterns with an aperture of 1.5 μm are required.

[0011] In addition, in order to achieve higher resolution pattern transfer, a phase shift mask blank having a phase shift film with a transmittance of 15% or more to exposure light and a phase shift mask formed with a phase shift film pattern with a transmittance of 15% or more to exposure light are required. It should be noted that in terms of the cleaning resistance (chemical properties) of the phase shift mask blank and the phase shift mask, a phase shift mask blank and a phase shift mask in which optical property changes caused by film reduction and surface composition changes of the phase shift film and the phase shift film pattern are suppressed are required, the phase shift mask blank is formed with a phase shift film having cleaning resistance, and the phase shift mask is formed with a phase shift film pattern having cleaning resistance.

[0012] In order to meet the requirements for the transmittance of exposure light and the requirements for cleaning resistance, it is effective to increase the ratio of silicon in the atomic ratio of metal to silicon in the metal silicide compound (metal silicide-type material) constituting the phase shift film. However, there are problems such as a significant delay in the wet etching rate (long wet etching time), damage to the substrate by the wet etching solution, and a decrease in the transmittance of the transparent substrate.

[0013] Furthermore, in the case of a binary mask blank having a light-shielding film containing a transition metal and silicon, when a light-shielding pattern is formed on the light-shielding film by wet etching, there is also a demand for cleaning resistance, and the same problem as described above exists.

[0014] Therefore, the present invention is completed in order to solve the above-mentioned problems, and an object of the present invention is to provide a photomask blank, a method for manufacturing a photomask blank, a method for manufacturing a photomask, and a method for manufacturing a display device, which can shorten the wet etching time when a transfer pattern is formed by wet etching on a pattern forming film such as a phase shift film or a light shielding film containing a transition metal and silicon, thereby being able to form a transfer pattern having a good cross-sectional shape, satisfying the cleaning resistance required in the pattern forming film or the transfer pattern, and satisfying the required line edge roughness.

[0015] Solutions to the problem

[0016] The inventors have conducted in-depth research on countermeasures for solving these problems. First, a material in which the atomic ratio of transition metal to silicon in the pattern-forming film is transition metal: silicon = 1:3 or more is made. In order to shorten the time of wet etching of the pattern-forming film using a wet etching solution, the oxygen contained in the sputtering gas introduced into the film forming chamber is adjusted so that the pattern-forming film contains a large amount of oxygen (O), thereby forming a pattern-forming film. As a result, although the wet etching speed for forming the transfer pattern becomes faster, the refractive index of the phase shift film in the phase shift mask blank to the exposure light is reduced, so the film thickness required to obtain the desired phase difference (for example, 180°) is thickened. In addition, for the light-shielding film in the binary mask blank, in order to reduce the extinction coefficient to the exposure light, the film thickness required to obtain the desired light-shielding performance (for example, the optical density (OD) is 3 or more) is thickened. The thickening of the film thickness of the pattern-forming film is not conducive to pattern formation by wet etching, and due to the thickening of the film thickness, the effect of shortening the wet etching time is limited. On the other hand, when the atomic ratio of transition metal to silicon is set to the above-mentioned transition metal: silicon = 1:3 or more, there are advantages such as improving the cleaning resistance of the pattern-forming film. Therefore, from this point of view, it is not preferred to deviate from the above-mentioned composition ratio of transition metal to silicon.

[0017] Therefore, the inventor changed his mind and studied the method of adjusting the pressure of the sputtering gas in the film forming chamber to change the film structure. When a film is formed on a substrate to form a pattern-forming thin film, the sputtering gas pressure in the film forming chamber is usually set to 0.1-0.5Pa. However, the inventor intentionally set the sputtering gas pressure to be greater than 0.5Pa to form a pattern-forming thin film. Then, a pattern-forming thin film was formed with a sputtering gas pressure of more than 0.8Pa and less than 3.0Pa. It was found that the film not only had suitable properties as a thin film, but also could significantly shorten the etching time when a transfer pattern was formed on the pattern-forming thin film by wet etching, thereby forming a transfer pattern with a good cross-sectional shape. Moreover, the pattern-forming thin film formed in this way has a columnar structure that is not found in conventional pattern-forming thin films.

[0018] The inventors of the present invention have further conducted in-depth research and have attempted to make a pattern-forming film into a multilayer including an upper layer and a lower layer, satisfying the above-mentioned sputtering gas pressure of more than 0.8Pa and less than 3.0Pa. On this basis, the sputtering gas pressure when forming the upper layer is lower than the sputtering gas pressure when forming the lower layer. That is, an attempt was made to make the vacuum degree in the film-forming chamber when forming the upper layer better than the vacuum degree in the film-forming chamber when forming the lower layer. In this way, when forming a pattern-forming film including an upper layer and a lower layer, it has the above-mentioned suitable properties as a film. On this basis, a transfer pattern that satisfies the cleaning resistance required in the pattern-forming film or the transfer pattern and the required line edge roughness can be formed. Moreover, the upper layer and the lower layer of the pattern-forming film formed in this way both have the above-mentioned columnar structure, and the size of the particles constituting the columnar structure in the upper layer is smaller than the size of the particles constituting the columnar structure in the above-mentioned lower layer.

[0019] The present invention is a result of the above intensive studies and has the following configurations.

[0020] (Scheme 1) A photomask blank having a pattern-forming thin film on a transparent substrate, wherein:

[0021] The photomask blank is an original plate for forming a photomask, and the photomask is a photomask having a transfer pattern on the transparent substrate obtained by wet etching the pattern-forming thin film.

[0022] The pattern-forming thin film contains a transition metal and silicon.

[0023] The pattern-forming film has a columnar structure,

[0024] The pattern-forming film comprises an upper layer and a lower layer,

[0025] An average size of particles constituting the columnar structure in the upper layer is smaller than an average size of particles constituting the columnar structure in the lower layer.

[0026] (Structure 2) The photomask blank according to Structure 1, wherein an atomic ratio of the transition metal to the silicon contained in the pattern-forming thin film is transition metal:silicon=1:3 or more and 1:15 or less.

[0027] (Structure 3) The photomask blank according to Structure 1 or 2, wherein the pattern-forming thin film contains at least nitrogen or oxygen.

[0028] (Structure 4) The photomask blank according to any one of Structures 1 to 3, wherein the transition metal is molybdenum.

[0029] (Scheme 5) A photomask blank according to any one of schemes 1 to 4, wherein the pattern-forming film is a phase shift film having the following optical properties: a transmittance of a representative wavelength of exposure light of greater than 1% and less than 80% and a phase difference of greater than 160° and less than 200°.

[0030] (Structure 6) The photomask blank according to any one of Structures 1 to 5, wherein an etching mask film having a different etching selectivity to the pattern-forming thin film is provided on the pattern-forming thin film.

[0031] (Scheme 7) The photomask blank according to scheme 6, wherein the etching mask film is formed of a material containing chromium but substantially containing no silicon.

[0032] (Scheme 8) A method for manufacturing a photomask blank, the method comprising: forming a pattern-forming thin film containing a transition metal and silicon on a transparent substrate by a sputtering method,

[0033] The pattern-forming thin film is formed by using a transition metal silicide target containing a transition metal and silicon in a film forming chamber and supplying a sputtering gas at a sputtering gas pressure of 0.8 Pa to 3.0 Pa.

[0034] The pattern-forming film comprises an upper layer and a lower layer,

[0035] The sputtering gas pressure in the film forming chamber when the upper layer is formed is lower than the sputtering gas pressure in the film forming chamber when the lower layer is formed.

[0036] (Scheme 9) The method for manufacturing a photomask blank according to scheme 8, wherein the atomic ratio of the transition metal to silicon in the transition metal silicide target is transition metal:silicon=1:3 or more and 1:15 or less.

[0037] (Scheme 10) The method for manufacturing a photomask blank according to scheme 8 or 9, wherein an etching mask film is formed on the pattern forming thin film using a sputtering target, and the sputtering target is formed of a material having a different etching selectivity with respect to the pattern forming thin film.

[0038] (Scheme 11) The method for manufacturing a photomask blank according to scheme 10, wherein the pattern forming thin film and the etching mask film are formed using an inline sputtering device.

[0039] (Scheme 12) A method for manufacturing a photomask, the method comprising:

[0040] A step of preparing the photomask blank according to any one of claims 1 to 5, or a photomask blank manufactured by the method for manufacturing a photomask blank according to claim 8 or 9;

[0041] A step of forming a resist film on the pattern-forming thin film, and wet-etching the pattern-forming thin film using a resist film pattern formed by the resist film as a mask to form a transfer pattern on the transparent substrate.

[0042] (Scheme 13) A method for manufacturing a photomask, the method comprising:

[0043] A step of preparing the photomask blank according to claim 6 or 7, or a photomask blank manufactured by the method for manufacturing a photomask blank according to claim 10 or 11;

[0044] forming a resist film on the etching mask film, and wet-etching the etching mask film using the resist film pattern formed by the resist film as a mask to form an etching mask film pattern on the pattern-forming thin film; and

[0045] A step of wet-etching the pattern-forming thin film using the etching mask film pattern as a mask to form a transfer pattern on the transparent substrate.

[0046] (Scheme 14) A method for manufacturing a display device, the method comprising:

[0047] An exposure step of placing the photomask obtained by the photomask manufacturing method according to claim 12 or 13 on a mask stage of an exposure device, and transferring the transfer pattern formed on the photomask to a resist formed on a display device substrate by exposure.

[0048] Effects of the Invention

[0049] According to the photomask blank or the method for manufacturing a photomask blank of the present invention, when a required fine transfer pattern is formed by wet etching a transfer pattern film, from the viewpoint of cleaning resistance, etc., when the pattern forming film is made of a silicon-rich metal silicide compound, a photomask blank can be obtained that can form a transfer pattern having a good cross-sectional shape, satisfying the cleaning resistance required in the pattern forming film or the transfer pattern, and satisfying the required line edge roughness within a short etching time.

[0050] In addition, according to the method for manufacturing a photomask of the present invention, a photomask is manufactured using the above-mentioned photomask blank. Therefore, from the viewpoint of cleaning resistance, when the pattern-forming film is made of a metal silicide compound rich in silicon, a photomask having good transfer accuracy, satisfying the cleaning resistance required in the pattern-forming film or the transfer pattern, satisfying the required line edge roughness, and not causing a decrease in the transmittance of the transparent substrate due to damage to the substrate by a wet etching solution can be manufactured. This photomask can cope with the miniaturization of line and space patterns and contact holes.

[0051] In addition, according to the manufacturing method of the display device of the present invention, the display device is manufactured using a photomask manufactured using the above-mentioned photomask blank or obtained by the above-mentioned photomask manufacturing method, so that a display device having a fine line and space pattern and contact holes can be manufactured. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 This is an explanatory diagram showing the film structure of the phase shift mask blank according to the first embodiment.

[0053] Figure 2 It is an explanatory diagram showing the film structure of the phase shift mask blank according to the second embodiment.

[0054] Figure 3 (a) to (e) are explanatory diagrams showing the manufacturing process of the phase shift mask according to the third embodiment.

[0055] Figure 4 (a) to (c) are explanatory diagrams showing the manufacturing process of the phase shift mask according to the fourth embodiment.

[0056] Explanation of symbols

[0057] 10…Phase shift mask blanks

[0058] 20…Transparent substrate

[0059] 30…Phase shift film

[0060] 30a…Phase shift film pattern

[0061] 31…Upper

[0062] 32…Lower level

[0063] 31a…Upper pattern

[0064] 32a…lower layer pattern

[0065] 40…Etching mask film

[0066] 40a ... first etching mask film pattern

[0067] 40b ... second etching mask film pattern

[0068] 50 ... first resist film pattern,

[0069] 60…Second resist pattern

[0070] 100…Phase shift mask DETAILED DESCRIPTION

[0071] Implementation methods 1 and 2

[0072] In Embodiments 1 and 2, a phase shift mask blank is described. The phase shift mask blank of Embodiment 1 is a master for forming a phase shift mask having a phase shift film pattern on a transparent substrate by wet etching the phase shift film using an etching mask film pattern having a desired pattern formed on an etching mask film as a mask. In addition, the phase shift mask blank of Embodiment 2 is a master for forming a phase shift film having a phase shift film pattern on a transparent substrate by wet etching the phase shift film using an etching resist film pattern having a desired pattern formed on a resist film as a mask.

[0073] Figure 1 1 is an explanatory diagram showing a film structure of the phase shift mask blank 10 according to the first embodiment.

[0074] Figure 1 The phase shift mask blank 10 shown includes a transparent substrate 20 , a phase shift film 30 formed on the transparent substrate 20 , and an etching mask film 40 formed on the phase shift film 30 .

[0075] Figure 2 It is an explanatory diagram showing the film structure of the phase shift mask blank 10 according to the second embodiment.

[0076] Figure 2 The phase shift mask blank 10 shown includes a transparent substrate 20 and a phase shift film 30 formed on the transparent substrate 20 .

[0077] Moreover, if Figure 1 , Figure 2 As shown, the phase shift film 30 includes an upper layer 31 and a lower layer 32 .

[0078] Hereinafter, the transparent substrate 20 , the phase shift film 30 , and the etching mask film 40 constituting the phase shift mask blank 10 according to the first and second embodiments will be described.

[0079] The transparent substrate 20 is transparent to the exposure light. When there is no surface reflection loss, the transparent substrate 20 has a transmittance of 85% or more, preferably a transmittance of 90% or more, to the exposure light. The transparent substrate 20 is made of a material containing silicon and oxygen, and can be composed of glass materials such as synthetic quartz glass, quartz glass, aluminosilicate glass, soda-lime glass, and low thermal expansion glass (SiO2-TiO2 glass, etc.). In the case where the transparent substrate 20 is composed of low thermal expansion glass, the position change of the phase shift film pattern caused by the thermal deformation of the transparent substrate 20 can be suppressed. In addition, the transparent substrate 20 used in the display device application is usually a rectangular substrate, and a substrate with a short side length of 300 mm or more can be used. The present invention is a phase shift mask blank, which can provide a phase shift mask, and the above-mentioned phase shift mask can stably transfer a fine phase shift film pattern, for example, less than 2.0 μm, formed on the transparent substrate even if the short side length of the transparent substrate is large and is 300 mm or more.

[0080] The phase shift film 30 is made of a transition metal silicide material containing a transition metal and silicon. As the transition metal, molybdenum (Mo), tantalum (Ta), tungsten (W), titanium (Ti), zirconium (Zr), etc. are suitable, and molybdenum (Mo) is particularly preferred.

[0081] In addition, the phase shift film 30 preferably contains at least nitrogen or oxygen. In the above-mentioned transition metal silicide-based materials, oxygen as a light element component has an effect of reducing the extinction coefficient compared with nitrogen as a light element component, and can reduce the content of other light element components (nitrogen, etc.) for obtaining the desired transmittance, and can effectively reduce the reflectivity of the surface and back of the phase shift film 30. In addition, in the above-mentioned transition metal silicide-based materials, nitrogen as a light element component has an effect of not reducing the refractive index compared with oxygen as a light element component, so the film thickness for obtaining the desired phase difference can be reduced. In addition, the total content of light element components including oxygen and nitrogen contained in the phase shift film 30 is preferably 40 atomic % or more, more preferably 40 atomic % or more and 70 atomic % or less, and preferably 50 atomic % or more and 65 atomic % or less. In addition, when oxygen is contained in the phase shift film 30, it is desirable that the content of oxygen is greater than 0 atomic % and less than 25 atomic % from the perspective of defect quality and chemical resistance. In addition, within the above-mentioned range of the total content of light element components, it is preferred that the total content of light element components in the upper layer 31 of the phase shift film 30 is smaller than the total content of light element components in the lower layer 32. By setting the relationship between the total content of light element components of the upper layer 31 and the lower layer 32 to the above-mentioned relationship, the refractive index n2 and the extinction coefficient k2 of the lower layer 32 at the representative wavelength of the exposure light can be made smaller than the refractive index n1 and the extinction coefficient k1 of the upper layer 31, and thus the back reflectivity at the representative wavelength of the exposure light can be reduced. Specifically, by appropriately adjusting the refractive index, extinction coefficient, and film thickness of the upper layer 31 and the lower layer 32, the back reflectivity of the phase shift film 30 at the representative wavelength of the exposure light (for example, h-line (wavelength 405nm)) can be made 15% or less. By setting the back reflectivity of the phase shift film 30 to 15% or less, the back reflectivity when the phase shift mask is set in the exposure device can be suppressed, and the return light from the exposure device to the optical system can be suppressed. Therefore, the pattern transfer property using the phase shift mask is also favorable and is therefore preferred. From the viewpoint of pattern transfer property, the back surface reflectance of the phase shift film 30 at the representative wavelength of exposure light is preferably 10% or less, more preferably 5% or less.

[0082] As transition metal silicide materials, for example, nitrides of transition metal silicides, oxides of transition metal silicides, oxynitrides of transition metal silicides, and carbonitride oxides of transition metal silicides can be cited. In addition, from the viewpoint of being easy to obtain an excellent pattern cross-sectional shape by wet etching, the transition metal silicide materials are preferably molybdenum silicide materials (MoSi materials), zirconium silicide materials (ZrSi materials), and molybdenum zirconium silicide materials (MoZrSi materials), and particularly preferably molybdenum silicide materials (MoSi materials).

[0083] Furthermore, in order to reduce film stress and control the wet etching rate, the phase shift film 30 may contain other light element components such as carbon and helium in addition to the above-mentioned oxygen and nitrogen.

[0084] The phase shift film 30 has a function of adjusting the reflectance of light incident from the transparent substrate 20 side (hereinafter, sometimes referred to as back surface reflectance) and a function of adjusting the transmittance and phase difference of exposure light.

[0085] The phase shift film 30 can be formed by a sputtering method.

[0086] The phase shift film 30 has a columnar structure. The columnar structure can be confirmed by cross-sectional SEM observation of the phase shift film 30. That is, the columnar structure of the present invention refers to a state in which the particles of the transition metal silicide compound containing transition metal and silicon constituting the phase shift film 30 have a columnar particle structure extending in the film thickness direction of the phase shift film 30 (the direction in which the above-mentioned particles are accumulated). It should be noted that, in the present application, particles whose length in the film thickness direction is longer than their length in the perpendicular direction are referred to as columnar particles. That is, the phase shift film 30 forms columnar particles extending in the film thickness direction within the entire surface of the transparent substrate 20. In addition, in the phase shift film 30, by adjusting the film forming conditions (sputtering pressure, etc.), a sparse portion (hereinafter sometimes referred to as a "sparse portion") having a relatively low density compared to the columnar particles is formed. It should be noted that, for the phase shift film 30, in order to effectively suppress the side etching during wet etching and make the pattern cross-sectional shape better, as a preferred form of the columnar structure of the phase shift film 30, columnar particles extending in the film thickness direction are preferably irregularly formed in the film thickness direction. It is further preferred that the columnar particles of the phase shift film 30 are in a state where the length in the film thickness direction is not aligned. Moreover, it is preferred to form the sparse part of the phase shift film 30 continuously in the film thickness direction. In addition, it is preferred to form the sparse part of the phase shift film 30 intermittently in a direction perpendicular to the film thickness direction. By forming the phase shift film 30 into the columnar structure as described above, when wet etching using a wet etching liquid, the wet etching liquid is easy to penetrate in the film thickness direction of the phase shift film 30, so the wet etching speed can be accelerated, and the wet etching time can be greatly shortened. Therefore, even if the phase shift film 30 is a metal silicide compound rich in silicon, the transmittance of the transparent substrate will not be reduced due to damage to the substrate by the wet etching liquid. Furthermore, since the phase shift film 30 has a columnar structure extending in the film thickness direction, side etching during wet etching can be suppressed and the pattern cross-sectional shape can be improved.

[0087] In addition, the average size of the particles of the columnar structure in the upper layer 31 of the phase shift film 30 is smaller than the average size of the particles of the columnar structure in the lower layer 32. The average size of the particles of the columnar structure here refers to the size obtained by averaging the size in the direction perpendicular to the film thickness direction of the phase shift film 30 (in-plane direction). The average size of the particles of the columnar structure is obtained by measuring the size of the particles of the columnar structure in the region of 300 nm in the in-plane direction near the film thickness center of the phase shift film 30 when observing the cross-sectional SEM photograph of the phase shift mask blank 10 having the phase shift film 30 at 80,000 times. In other words, the frequency of occurrence of the sparse portion in the upper layer 31 of the phase shift film 30 is generally smaller than the sparse portion of the columnar structure in the lower layer 32. With such a configuration of the phase shift film 30, the average size of the particles of the columnar structure in the upper layer 31 is smaller than that of the lower layer 32 (the number of sparse portions of the columnar structure is small), so that the cleaning resistance required for the phase shift film 30 can be satisfied, and the line edge roughness when the phase shift film 30 is patterned also satisfies the required characteristics. On the other hand, the average size of the particles of the columnar structure in the lower layer 32 is larger than that of the upper layer 31 (there are many sparse parts of the columnar structure), so that the side etching during wet etching can be effectively suppressed, and the cross-sectional shape of the phase shift film pattern after the phase shift film 30 is wet-etched can be made good. That is, the phase shift film 30 having such an upper layer 31 and a lower layer 32 can form a phase shift film pattern that satisfies the cleaning resistance required in the phase shift film 30 or the phase shift film pattern 30a, satisfies the required line edge roughness, and has a good cross-sectional shape.

[0088] Here, the average size of the main particles of the columnar structure in the upper layer 31 is preferably 5 to 30 nm, and the average size of the particles of the columnar structure in the lower layer 32 is preferably 10 to 40 nm.

[0089] The atomic ratio of transition metal to silicon contained in the phase shift film 30 is preferably transition metal: silicon = 1:3 or more and 1:15 or less. In this range, the effect of suppressing the wet etching rate reduction of the phase shift film 30 during patterning by the columnar structure can be increased. In addition, the cleaning resistance of the phase shift film 30 can be improved, and the transmittance can be easily improved. From the viewpoint of improving the cleaning resistance of the phase shift film 30, the atomic ratio of transition metal to silicon contained in the phase shift film 30 is preferably transition metal: silicon = 1:4 or more and 1:15 or less, and more preferably transition metal: silicon = 1:5 or more and 1:15 or less.

[0090] The transmittance of the phase shift film 30 with respect to the exposure light satisfies the value required as the phase shift film 30. The transmittance of the phase shift film 30 with respect to the light of a given wavelength (hereinafter referred to as a representative wavelength) included in the exposure light is preferably 1% or more and 80% or less, more preferably 15% or more and 65% or less, and further preferably 20% or more and 60% or less. That is, when the exposure light is a composite light including light of a wavelength range of 313nm or more and 436nm or less, the phase shift film 30 has the above transmittance with respect to the light of the representative wavelength included in the wavelength range. For example, when the exposure light is a composite light including i-line, h-line, and g-line, the phase shift film 30 has the above transmittance with respect to any one of the i-line, h-line, and g-line.

[0091] The transmittance can be measured using a phase shift measurement device or the like.

[0092] The phase difference of the phase shift film 30 with respect to the exposure light satisfies the value required as the phase shift film 30. The phase difference of the phase shift film 30 with respect to the light of the representative wavelength included in the exposure light is preferably 160° or more and 200° or less, and more preferably 170° or more and 190° or less. By utilizing this property, the phase of the light of the representative wavelength included in the exposure light can be changed to 160° or more and 200° or less. Therefore, a phase difference of 160° or more and 200° or less is generated between the light of the representative wavelength that has passed through the phase shift film 30 and the light of the representative wavelength that has only passed through the transparent substrate 20. That is, when the exposure light is a composite light including light of a wavelength range of 313nm or more and 436nm or less, the phase shift film 30 has the above-mentioned phase difference with respect to the light of the representative wavelength included in the wavelength range. For example, when the exposure light is a composite light including i-line, h-line and g-line, the phase shift film 30 has the above-mentioned phase difference with respect to any one of the i-line, h-line and g-line.

[0093] The phase difference can be measured using a phase shift measurement device or the like.

[0094] Furthermore, by making the refractive index and extinction coefficient of the upper layer 31 of the phase shift film 30 larger than those of the lower layer 32 and appropriately setting the film thicknesses of the upper layer 31 and the lower layer 32, the back surface reflectivity of the phase shift film 30 can be reduced.

[0095] The back reflectivity of the phase shift film 30 is 15% or less, preferably 10% or less at a representative wavelength in the wavelength range of 365nm to 436nm. In addition, when the exposure light includes a j line, the back reflectivity of the phase shift film 30 is preferably 20% or less, more preferably 17% or less, and further preferably 15% or less at a representative wavelength in the wavelength range of 313nm to 436nm. It is desired that the back reflectivity of the phase shift film 30 is preferably 15% or less, and further preferably 10% or less in the entire region of the wavelength range of 365nm to 436nm. In addition, the back reflectivity of the phase shift film 30 is preferably 0.2% or more at a representative wavelength in the wavelength range of 365nm to 436nm, and is preferably 0.2% or more at a representative wavelength in the wavelength range of 313nm to 436nm. It is desirable that the back surface reflectivity of the phase shift film 30 is preferably 0.2% or more in the entire wavelength range of 365 nm to 436 nm, or preferably 0.2% or more in the entire wavelength range of 313 nm to 436 nm.

[0096] The back surface reflectance can be measured using a spectrophotometer or the like.

[0097] It should be noted that, in these embodiments, the phase shift film 30 is described as being composed of two layers, the upper layer 31 and the lower layer 32, but it is not limited to this structure and may be composed of three or more layers. In this case, it is preferred that the size of the columnar particles in the upper layer is smaller than the average size of the columnar particles in the lower layer.

[0098] The etching mask film 40 is arranged on the upper side of the phase shift film 30, and is formed of a material having etching resistance to the etching solution for etching the phase shift film 30 (different from the etching selectivity of the phase shift film 30). In addition, the etching mask film 40 can have a function of shielding the exposure light from being transmitted, and can also have a function of reducing the film surface reflectivity, so that the film surface reflectivity of the phase shift film 30 is 15% or less relative to the light incident from the side of the phase shift film 30 in the wavelength range of 350nm to 436nm. The etching mask film 40 is composed of a chromium-based material containing chromium (Cr). More specifically, as the chromium-based material, chromium (Cr) or a material containing chromium (Cr) and at least one of oxygen (O), nitrogen (N), and carbon (C) can be cited. Alternatively, a material containing chromium (Cr) and at least one of oxygen (O), nitrogen (N), and carbon (C) and also containing fluorine (F) can be cited. For example, as a material constituting the etching mask film 40, Cr, CrO, CrN, CrF, CrCO, CrCN, CrON, CrCON, and CrCONF can be cited. In addition, the etching mask film 40 is preferably formed of a material that does not substantially contain silicon. Here, the material that does not substantially contain silicon refers to a material in which the content of silicon contained in the etching mask film 40 is 2 atomic % or less. In addition, the content of silicon in the etching mask film 40 is preferably less than the detection lower limit of the measuring device.

[0099] The etching mask film 40 can be formed by a sputtering method.

[0100] When the etching mask film 40 has a function of blocking the exposure light from passing therethrough, the optical density of the exposure light in the portion where the phase shift film 30 and the etching mask film 40 are stacked is preferably 3 or more, more preferably 3.5 or more, and even more preferably 4 or more.

[0101] Optical density can be measured using a spectrophotometer or an OD meter.

[0102] Depending on the function, the etching mask film 40 may be formed of a single film having a uniform composition, may be formed of a plurality of films having different compositions, or may be formed of a single film having a composition that continuously changes in the thickness direction.

[0103] It should be noted that Figure 1 The phase shift mask blank 10 shown includes the etching mask film 40 on the phase shift film 30 , but 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 an etching resist film on the etching mask film 40 .

[0104] Next, a method for manufacturing the phase shift mask blank 10 according to the first and second embodiments will be described. Figure 1 The phase shift mask blank 10 shown can be manufactured by performing the following phase shift film forming step and etching mask film forming step. Figure 2The phase shift mask blank 10 shown can be manufactured by performing a phase shift film forming process.

[0105] Hereinafter, each step will be described in detail.

[0106] 1. Phase shift film formation process

[0107] First, prepare the transparent substrate 20. The transparent substrate 20 may be made of any glass material such as synthetic quartz glass, quartz glass, aluminosilicate glass, soda-lime glass, or low thermal expansion glass (SiO2-TiO2 glass, etc.) as long as it is transparent to exposure light.

[0108] Next, the phase shift film 30 is formed on the transparent substrate 20 by sputtering.

[0109] A transition metal silicide target containing a transition metal and silicon as the main component of the material constituting the phase shift film 30, or a transition metal silicide target containing a transition metal, silicon, oxygen and / or nitrogen is used as a sputtering target, and the phase shift film 30 is formed in a sputtering gas atmosphere, for example, a sputtering gas atmosphere formed by at least one inert gas selected from helium, neon, argon, krypton and xenon, or a sputtering gas atmosphere formed by a mixed gas of the inert gas and an active gas selected from oxygen, nitrogen, carbon dioxide, nitric oxide and nitrogen dioxide and containing at least oxygen and nitrogen. Then, the phase shift film 30 is formed in an atmosphere in which the gas pressure in the film forming chamber supplied with the sputtering gas is 0.8 Pa or more and 3.0 Pa or less. By setting the range of the gas pressure in this way, a columnar structure can be formed in the phase shift film 30. With this columnar structure, not only can side etching during pattern formation described later be suppressed, but also a high etching rate can be achieved. Here, from the viewpoints that the columnar structure has a great effect in suppressing the reduction in wet etching rate, can improve the cleaning resistance of the phase shift film 30, and can easily improve the transmittance, the atomic ratio of transition metal to silicon in the transition metal silicide target is preferably transition metal:silicon = 1:3 or more and 1:15 or less.

[0110] When forming the phase shift film 30, the sputtering gas pressure of 0.8 Pa or more and 3.0 Pa or less is satisfied. On this basis, the sputtering gas pressure when forming the upper layer 31 of the phase shift film 30 is made lower than the sputtering gas pressure when forming the lower layer 32 of the phase shift film 30 (that is, the vacuum degree in the film forming chamber when forming the upper layer 31 is made better than the vacuum degree in the film forming chamber when forming the lower layer 32), and the phase shift film 30 including the upper layer 31 and the lower layer 32 is formed. Here, the sputtering gas pressure when forming the upper layer 31 is preferably 0.8 Pa or more and 1.5 Pa or less, and the sputtering gas pressure when forming the lower layer 32 is preferably 1.2 Pa or more and 3.0 Pa or less. The sputtering gas pressure can be adjusted by the opening amount of the main valve of the vacuum pump connected to the film forming chamber.

[0111] By adjusting the vacuum degree during the film formation of the upper layer 31 and the lower layer 32 as described above, the size of the particles constituting the columnar structure in the upper layer 31 can be made smaller than the size of the particles constituting the columnar structure in the lower layer 32. Thus, the phase shift mask blank 10 capable of forming the phase shift film pattern 30a having a good cross-sectional shape, satisfying the cleaning resistance required in the phase shift film 30 or the phase shift film pattern 30a, and satisfying the required line edge roughness can be obtained.

[0112] The difference between the sputtering gas pressure when forming the upper layer 31 and the sputtering gas pressure when forming the lower layer 32 is preferably 0.3 Pa or more and 1.2 Pa or less, and more preferably 0.4 Pa or more and 1.0 Pa or less. When the difference between the sputtering gas pressure when forming the upper layer 31 and the sputtering gas pressure when forming the lower layer 32 is less than 0.3 Pa, the difference in effect (good cross-sectional shape, required cleaning resistance, line edge roughness) between a single-layer phase shift film 30 or a phase shift film 30 formed by multi-layer film formation under the same film forming conditions and the phase shift film 30 in the present invention becomes smaller. In addition, when the difference between the sputtering gas pressure when forming the upper layer 31 and the sputtering gas pressure when forming the lower layer 32 exceeds 1.2 Pa, a difference occurs in the side etching amount of the upper layer 31 and the lower layer 32 when the phase shift film 30 is patterned by wet etching, and therefore, a height difference is easily generated in the cross-sectional shape of the phase shift film pattern, which is not preferred.

[0113] The composition and thickness of the phase shift film 30 can be adjusted so that the phase shift film 30 has the above-mentioned 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 ratio of transition metals to the content ratio of silicon), the composition and flow rate of the sputtering gas, etc. The thickness of the phase shift film 30 can be controlled by the sputtering power, the sputtering time, etc. In addition, the phase shift film 30 is preferably formed using an inline sputtering device. In the case where the sputtering device is an inline sputtering device, the thickness of the phase shift film 30 can be controlled by the conveying speed of the substrate. Thus, the content ratio of the light element components including oxygen and nitrogen in the phase shift film 30 can be controlled to be greater than 40 atomic % and less than 70 atomic %.

[0114] Furthermore, the upper layer 31 of the phase shift film 30 is preferably thinner than the lower layer 32. This is because the upper layer 31 mainly has the function of improving the cleaning resistance of the phase shift film 30 and reducing the line edge roughness, and the lower layer 32 mainly has the function of shortening the wet etching time and making the cross-sectional shape good. More specifically, the overall thickness of the phase shift film 30 is preferably 120nm to 250nm, and on this basis, the thickness of the upper layer 31 is preferably 10nm to 50nm, and the thickness of the lower layer 32 is preferably 70nm to 240nm.

[0115] When the phase shift film 30 is formed of a plurality of films having different compositions, the composition and flow rate of the sputtering gas are appropriately adjusted to perform the above-mentioned film forming process a plurality of times. The phase shift film 30 may be formed using targets having different content ratios of elements constituting the sputtering target. When the film forming process is performed a plurality of times, the sputtering power applied to the sputtering target may be changed according to the film forming process.

[0116] 2. Surface treatment process

[0117] In the case where the phase shift film 30 is formed of a transition metal silicide material containing oxygen, such as a transition metal silicide oxide containing a transition metal, silicon, and oxygen, or a transition metal silicide oxynitride containing a transition metal, silicon, oxygen, and nitrogen, a surface treatment step for adjusting the surface oxidation state of the phase shift film 30 may be performed on the surface of the phase shift film 30 in order to suppress the infiltration of an etching solution due to the presence of the transition metal oxide. It should be noted that, in the case where the phase shift film 30 is formed of a transition metal silicide nitride containing a transition metal, silicon, and nitrogen, the content of the transition metal oxide is less than that of the above-mentioned transition metal silicide material containing oxygen. Therefore, in the case where the material of the phase shift film 30 is a transition metal silicide nitride, the above-mentioned surface treatment step may be performed or may not be performed.

[0118] Examples of the surface treatment process for adjusting the surface oxidation state of the phase shift film 30 include a method of surface treatment using an acidic aqueous solution, a method of surface treatment using an alkaline aqueous solution, and a method of surface treatment by dry treatment such as ashing.

[0119] Thus, the phase shift mask blank 10 of Embodiment 2 can be obtained. In the production of the phase shift mask blank 10 of Embodiment 1, the following etching mask film forming step can be further performed.

[0120] 3. Etching mask film formation process

[0121] After the phase shift film forming step, a surface treatment for adjusting the surface oxidation state of the phase shift film 30 may be performed as needed, and then an etching mask film 40 is formed on the phase shift film 30 by sputtering. The etching mask film 40 is preferably formed using an inline sputtering device. When the sputtering device is an inline sputtering device, the thickness of the etching mask film 40 can be controlled by the conveying speed of the transparent substrate 20.

[0122] Using a sputtering target containing chromium or a chromium compound (chromium oxide, chromium nitride, chromium carbide, chromium oxynitride, chromium carbonitride, etc.), the etching mask film 40 is formed in the following sputtering gas atmosphere, the sputtering gas atmosphere is, for example, a sputtering gas atmosphere formed by at least one inactive gas selected from helium, neon, argon, krypton and xenon, or a sputtering gas atmosphere formed by a mixed gas of an inactive gas and an active gas, the inactive gas includes at least one selected from helium, neon, argon, krypton and xenon, and the active gas includes at least one selected from oxygen, nitrogen, nitric oxide gas, nitrogen dioxide gas, carbon dioxide gas, hydrocarbon gas, fluorine gas. As hydrocarbon gas, for example: methane gas, butane gas, propane gas, styrene gas, etc. can be cited. Then, by adjusting the gas pressure in the film forming chamber during sputtering, the etching mask film 40 can be formed into a columnar structure in the same manner as the phase shift film 30. Thus, not only can the side etching during the pattern formation described later be suppressed, but also a high etching rate can be achieved.

[0123] In the case where the etching mask film 40 is formed of a single film having a uniform composition, the above-mentioned film forming process is performed only once without changing the composition and flow rate of the sputtering gas. In the case where the etching mask film 40 is formed of a plurality of films having different compositions, the above-mentioned film forming process is performed a plurality of times while changing the composition and flow rate of the sputtering gas according to the film forming process. In the case where the etching mask film 40 is formed of a single film having a composition that continuously changes along the thickness direction, the composition and flow rate of the sputtering gas are changed together with the elapsed time of the film forming process, and the above-mentioned film forming process is performed only once.

[0124] In this way, the phase shift mask blank 10 of the first embodiment can be obtained.

[0125] It should be noted that due to Figure 1 The phase shift mask blank 10 shown in the figure has an etching mask film 40 on the phase shift film 30. Therefore, when manufacturing the phase shift mask blank 10, an etching mask film forming step is performed. In addition, when manufacturing a phase shift mask blank having an etching mask film 40 on the phase shift film 30 and an anti-etching film on the etching mask film 40, the anti-etching film is formed on the etching mask film 40 after the etching mask film forming step. Figure 2 In the phase shift mask blank 10 shown, when manufacturing a phase shift mask blank including a resist film on the phase shift film 30 , the resist film is formed after the phase shift film forming step.

[0126] The phase shift mask blank 10 of the first embodiment has an etching mask film 40 formed on the phase shift film 30, and at least the phase shift film 30 has a columnar structure. In addition, the phase shift mask blank 10 of the second embodiment has a phase shift film 30 formed thereon, and the phase shift film 30 has a columnar structure.

[0127] In the phase shift mask blank 10 of the first and second embodiments, when the phase shift film 30 is patterned by wet etching, etching in the film thickness direction is promoted and side etching is suppressed, so that the cross-sectional shape is good, and a phase shift film pattern having a desired transmittance (for example, high transmittance) and satisfying the cleaning resistance required in the phase shift film or the phase shift film pattern and satisfying the required line edge roughness can be formed in a short etching time. Therefore, a phase shift mask blank capable of manufacturing a phase shift mask can be obtained, and the above-mentioned phase shift mask can transfer a high-definition phase shift film pattern with good accuracy without reducing the transmittance of the transparent substrate due to damage to the substrate by the wet etching solution.

[0128] Implementation methods 3 and 4

[0129] In Embodiments 3 and 4, a method for manufacturing a phase shift mask will be described.

[0130] Figure 3 It is an explanatory diagram showing a method for manufacturing a phase shift mask according to the third embodiment. Figure 4 It is an explanatory diagram showing a method for manufacturing a phase shift mask according to a fourth embodiment.

[0131] Figure 3 The phase shift mask is manufactured using Figure 1 The method for manufacturing a phase shift mask using the phase shift mask blank 10 shown in the figure includes: a step of forming a resist film on an etching mask film 40 of the phase shift mask blank 10 as follows; a step of forming a resist film pattern 50 by drawing / developing a desired pattern on the resist film (a first resist film pattern forming step); a step of wet-etching the etching mask film 40 using the resist film pattern 50 as a mask to form an etching mask film pattern 40a on the phase shift film 30 (a first etching mask film pattern forming step); a step of wet-etching the phase shift film 30 using the etching mask film pattern 40a as a mask to form a phase shift film pattern 30a on the transparent substrate 20 (a phase shift film pattern forming step). Furthermore, the method also includes a second resist film pattern forming step and a second etching mask film pattern forming step.

[0132] Figure 4 The phase shift mask is manufactured using Figure 2 The method for manufacturing a phase shift mask using the phase shift mask blank 10 shown in the figure includes: a process of forming a resist film on the phase shift mask blank 10 as follows; forming a resist film pattern 50 by drawing / developing a desired pattern on the resist film (a first resist film pattern forming process); wet etching the phase shift film 30 using the resist film pattern 50 as a mask to form a phase shift film pattern 30a on a transparent substrate 20 (a phase shift film pattern forming process).

[0133] Hereinafter, each step of the process of manufacturing the phase shift mask of Embodiments 3 and 4 will be described in detail.

[0134] Phase shift mask manufacturing process according to Embodiment 3

[0135] 1. First resist film pattern forming step

[0136] 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 of the first embodiment. The resist film material used is not particularly limited. For example, it can be a material that is sensitive to a laser having any wavelength selected from the wavelength range of 350nm to 436nm as described later. In addition, the resist film can be either positive or negative.

[0137] Then, a desired pattern is drawn on the resist film using a laser having an arbitrary wavelength selected from the wavelength range of 350 nm to 436 nm. The pattern drawn on the resist film is the pattern 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.

[0138] Then, the resist film is developed with a given developer, such as Figure 3 As shown in (a), a first resist film pattern 50 is formed on the etching mask film 40.

[0139] 2. First Etching Mask Film Pattern Forming Step

[0140] In the first etching mask film pattern forming step, first, the etching mask film 40 is etched using the first anti-etching film pattern 50 as a mask to form the first etching mask film pattern 40a. The etching mask film 40 is formed of a chromium-based material containing chromium (Cr). From the viewpoint of being able to accelerate the etching speed and suppress side etching, it is preferred that the etching mask film 40 has a columnar structure. 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 nitrate and perchloric acid can be cited.

[0141] Then, use a resist stripping solution or by ashing, such as Figure 3 As shown in (b), the first resist film pattern 50 is peeled off. Depending on the situation, the following phase shift film pattern forming step may be performed without peeling off the first resist film pattern 50.

[0142] 3. Phase shift film pattern forming process

[0143] In the first phase shift film pattern forming step, the phase shift film 30 including the upper layer 31 and the lower layer 32 is wet-etched using the first etching mask film pattern 40a as a mask. Figure 3As shown in (c), a phase shift film pattern 30a including an upper layer pattern 31a and a lower layer pattern 32a is formed. 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 including ammonium fluoride, phosphoric acid and hydrogen peroxide, and an etching solution including ammonium hydrogen fluoride and hydrogen peroxide can be mentioned.

[0144] In order to make the cross-sectional shape of the phase shift film pattern 30a good, wet etching is preferably performed for a time (over-etching time) longer than the time (proper etching time) until the transparent substrate 20 is exposed in the phase shift film pattern 30a. The over-etching time is preferably set to a time obtained by adding 20% ​​of the proper etching time to the proper etching time, and more preferably to a time obtained by adding 10% of the proper etching time, in consideration of the influence on the transparent substrate 20, etc.

[0145] 4. Second resist film pattern forming step

[0146] 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 used is not particularly limited. For example, any material that is sensitive to a laser having any wavelength selected from the wavelength range of 350nm to 436nm described later can be used. In addition, the resist film can be either positive or negative.

[0147] Then, a desired pattern is drawn on the resist film using a laser having an arbitrary wavelength selected from the wavelength range of 350 nm to 436 nm. The pattern drawn on the resist film is a light-shielding band pattern for shielding the peripheral area of ​​the area where the pattern is formed on the phase shift film 30, a light-shielding band pattern for shielding the central part of the phase shift film pattern, etc. 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 pattern without a light-shielding band pattern for shielding the central part of the phase shift film pattern 30a.

[0148] Then, the resist film is developed with a given developer, such as Figure 3 As shown in (d), a second resist film pattern 60 is formed on the first etching mask film pattern 40a.

[0149] 5. Second Etching Mask Film Pattern Formation Step

[0150] 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. Figure 3(e) shows the formation of the second etching mask film pattern 40b. The first etching mask film pattern 40a is formed of 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 nitrate and perchloric acid can be cited.

[0151] Then, the second resist film pattern 60 is removed using a resist stripping solution or by ashing.

[0152] Thus, the phase shift mask 100 can be obtained.

[0153] It should be noted that, in the above description, the case where the etching mask film 40 has the function of blocking the transmission of exposure light is described, but 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 anti-etching film pattern forming process and the second etching mask film pattern forming process are not performed, and the first etching mask film pattern is peeled off after the phase shift film pattern forming process to produce the phase shift mask 100.

[0154] According to the method for manufacturing a phase shift mask of the third embodiment, since the phase shift mask blank of the first embodiment is used, the etching time can be shortened, and a phase shift film pattern with a good cross-sectional shape can be formed. Therefore, a phase shift mask capable of transferring a high-definition phase shift film pattern with good accuracy can be manufactured. The phase shift mask manufactured in this way can cope with the miniaturization of line and space patterns and contact holes.

[0155] Phase shift mask manufacturing process according to Embodiment 4

[0156] 1. Resist film pattern forming process

[0157] In the resist film pattern forming step, first, a resist film is formed on the phase shift film 30 of the phase shift mask blank 10 of Embodiment 2. The resist film material used is the same as that described in Embodiment 3. It should be noted that, in order to achieve good adhesion with the phase shift film 30, the surface of the phase shift film 30 may be subjected to surface modification treatment as needed before the resist film is formed. After the resist film is formed in the same manner as described above, a desired pattern is drawn on the resist film using a laser having an arbitrary wavelength selected from the wavelength range of 350 nm to 436 nm. Then, the resist film is developed using a given developer, such as Figure 4 As shown in (a), a resist film pattern 50 is formed on the phase shift film 30.

[0158] 2. Phase shift film pattern forming process

[0159] In the phase shift film pattern forming process, the phase shift film 30 including the upper layer 31 and the lower layer 32 is etched using the resist film pattern as a mask. Figure 4As shown in (b), a phase shift film pattern 30a including an upper layer pattern 31a and a lower layer pattern 32a is formed. The etching solution and over-etching time for etching the phase shift film pattern 30a and the phase shift film 30 are the same as those described in the third embodiment.

[0160] Then, the resist film pattern 50 is removed using a resist stripping solution or by ashing ( Figure 4 (c)).

[0161] Thus, the phase shift mask 100 can be obtained.

[0162] According to the method for manufacturing a phase shift mask of the fourth embodiment, since the phase shift mask blank of the second embodiment is used, the etching time can be shortened, and a phase shift film pattern with a good cross-sectional shape can be formed without causing a decrease in the transmittance of the transparent substrate due to damage to the substrate by a wet etching solution. Therefore, a phase shift mask capable of transferring a high-definition phase shift film pattern with good accuracy can be manufactured. The phase shift mask manufactured in this way can cope with the miniaturization of line and space patterns and contact holes.

[0163] Implementation method 5.

[0164] In Embodiment 5, a method for manufacturing a display device is described. The display device can be manufactured by a process (mask placement process) of using a phase shift mask 100 manufactured using the above-mentioned phase shift mask blank 10 or by the above-mentioned method for manufacturing the phase shift mask 100 and a process (exposure process) of transferring a transfer pattern to a resist film on the display device by exposure.

[0165] Hereinafter, each step will be described in detail.

[0166] 1. Placement process

[0167] In the placement step, the phase shift mask manufactured in Embodiment 3 is placed on a mask stage of an exposure device. Here, the phase shift mask is arranged to face the resist film formed on the display device substrate via the projection optical system of the exposure device.

[0168] 2. Pattern transfer process

[0169] In the pattern transfer process, the phase shift mask 100 is irradiated with exposure light to transfer the phase shift film pattern to the resist film formed on the display device substrate. The exposure light can be a composite light containing a plurality of wavelengths selected from the wavelength range of 365nm to 436nm, or a monochromatic light selected by removing a certain wavelength range from the wavelength range of 365nm to 436nm using a filter. For example, the exposure light is a composite light containing i-line, h-line and g-line, or i-line monochromatic light. When the composite light is used as the exposure light, the exposure light intensity can be increased to increase the luminous flux, thereby reducing the manufacturing cost of the display device.

[0170] According to the method for manufacturing a display device of Embodiment 3, a high-definition display device having a high resolution, a fine line and space pattern, and a contact hole can be manufactured.

[0171] It should be noted that, in the above embodiments, as the photomask blank having a pattern-forming film and the photomask having a transfer pattern, a phase-shift mask blank having a phase-shift film and a phase-shift mask having a phase-shift film pattern are described, but the present invention is not limited thereto. For example, the present invention can also be applied to a binary mask blank having a light-shielding film as a pattern-forming film and a binary mask having a light-shielding film pattern.

[0172] Example

[0173] Example 1.

[0174] A. Phase-Shift Mask Blanks and Methods of Making Them

[0175] In order 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 transparent substrate 20 .

[0176] Then, the synthetic quartz glass substrate is placed on a tray (not shown) with the main surface facing downward, and is transported into the chamber of the inline sputtering apparatus.

[0177] In order to form the lower layer 32 of the phase shift film 30 on the main surface of the transparent substrate 20, first, an inert gas composed of argon (Ar) and nitrogen (N2) (Ar: 18 sccm, N2: 13 sccm) was introduced while the sputtering gas pressure in the first chamber was set to 1.6 Pa. Then, a sputtering power of 7.6 kW was applied to a first sputtering target containing molybdenum and silicon (molybdenum: silicon = 11:89), and a nitride of molybdenum silicide containing molybdenum, silicon and nitrogen was deposited on the main surface of the transparent substrate 20 by reactive sputtering, thereby forming a lower layer 32 with a thickness of 115 nm. Then, the opening amount of the main valve of the vacuum pump connected to the first chamber was adjusted to set the sputtering gas pressure in the first chamber to 1.2 Pa, and an upper layer 31 with a thickness of 30 nm was formed on the lower layer 32 by reactive sputtering under the same conditions as those for the lower layer 32. In this way, a phase shift film 30 with a film thickness of 145 nm was formed.

[0178] Next, the transparent substrate 20 with the phase shift film 30 was transported to the second chamber, and a mixed gas of argon (Ar) and nitrogen (N2) (Ar: 65 sccm, N2: 15 sccm) was introduced into the second chamber. Then, a sputtering power of 1.5 kW was applied to the second sputtering target containing chromium, and chromium nitride (CrN) containing chromium and nitrogen (film thickness 15 nm) was formed on the phase shift film 30 by reactive sputtering. Next, in a state where a predetermined vacuum degree was set in the third chamber, a mixed gas (30 sccm) of argon (Ar) gas and methane (CH4: 4.9%) gas was introduced, and a sputtering power of 8.5 kW was applied to the third sputtering target containing chromium, and chromium carbide (CrC) containing chromium and carbon (film thickness 60 nm) was formed on CrN by reactive sputtering. Finally, in the state where the fourth chamber is set to a given vacuum degree, a mixed gas of argon (Ar) and methane (CH4: 5.5%) gas and a mixed gas of nitrogen (N2) and oxygen (O2) (Ar+CH4: 30 sccm, N2: 8 sccm, O2: 3 sccm) are introduced, and a sputtering power of 2.0 kW is applied to the fourth sputtering target containing chromium, and chromium carbonitride oxide (CrCON) containing chromium, carbon, oxygen and nitrogen (film thickness 30 nm) is formed on CrC by reactive sputtering. As described above, an etching mask film 40 having a stacked structure of a CrN layer, a CrC layer and a CrCON layer is formed on the phase shift film 30.

[0179] Thus, the phase shift mask blank 10 in which the phase shift film 30 and the etching mask film 40 are formed on the transparent substrate 20 is obtained.

[0180] The transmittance and phase difference of the phase shift film 30 (the surface of the phase shift film 30) of the obtained phase shift mask blank 10 were measured using MPM-100 manufactured by Lasertec. In the measurement of the transmittance and phase difference of the phase shift film 30, a substrate with a phase shift film (model substrate) in which the phase shift film 30 was formed on the main surface of a synthetic quartz glass substrate was used. The substrate with a phase shift film (model substrate) was mounted on the same tray. Before forming the etching mask film 40, the substrate with a phase shift film (model substrate) was taken out from the chamber, and the transmittance and phase difference of the phase shift film 30 were measured. As a result, the transmittance was 25.1% (wavelength: 405nm), the phase difference was 176° (wavelength: 405nm), and the back reflectivity was 9.4% (wavelength: 405nm).

[0181] Furthermore, the optical properties of the upper layer 31 and the lower layer 32 in the phase shift film 30 were measured using a spectroscopic ellipsometer (M-2000D manufactured by JA Woollam Co., Ltd.). As a result, the upper layer 31 had a refractive index of 2.49 and an extinction coefficient of 0.32. Furthermore, the lower layer 32 had a refractive index of 2.37 and an extinction coefficient of 0.24. It should be noted that, regarding the upper layer 31, the optical properties were measured for a sample in which only the upper layer 31 was formed on another transparent substrate (the same was true in Example 2).

[0182] In addition, the obtained phase shift mask blank 10 was subjected to composition analysis in the depth direction by X-ray photoelectron spectroscopy (XPS).

[0183] As a result of the depth-direction composition analysis of the phase shift mask blank 10 by XPS, in the phase shift film 30, the atomic ratio of molybdenum to silicon in the depth direction is substantially constant at 1:5.6, which is within the range of 1:3 or more and 1:15 or less, except for the composition gradient region at the interface between the transparent substrate 20 and the phase shift film 30 and the composition gradient region at the interface between the phase shift film 30 and the etching mask film 40. In addition, as for the content of each constituent element, in the upper layer 31, Mo is 7 atomic %, Si is 39 atomic %, N is 51 atomic %, and O is 3 atomic %, and in the lower layer 32, Mo is 7 atomic %, Si is 39 atomic %, N is 46 atomic %, and O is 8 atomic %. In addition, as for the total content of oxygen and nitrogen as light elements, in the upper layer 31, it is 54 atomic %, and in the lower layer 32, it is 54 atomic %, both within the range of 50 atomic % or more and 65 atomic %. It should be noted that the phase shift film 30 contains oxygen because the sputtering gas pressure is as high as 0.8 Pa or more and a small amount of oxygen exists in the chamber during film formation.

[0184] Next, a cross-sectional SEM (scanning electron microscope) observation was performed at a magnification of 80,000 times at the central position of the transfer pattern forming region of the obtained phase shift mask blank 10, and it was confirmed that the phase shift film 30 had a columnar structure. That is, it was confirmed that the particles of the molybdenum silicide compound constituting the phase shift film 30 had a columnar particle structure extending in the film thickness direction of the phase shift film 30. It was also confirmed that the columnar particle structure of the phase shift film 30 was in a state where columnar particles in the film thickness direction were irregularly formed and the lengths of the columnar particles in the film thickness direction were inconsistent. It was also confirmed that the sparse portion of the phase shift film 30 was continuously formed in the film thickness direction. In addition, it was also confirmed that the average size of the columnar particles in the upper layer 31 of the phase shift film 30 was smaller than the average size of the columnar particles in the layer 32. The average size of the columnar particles in the upper layer 31 was 14 nm, and the average size of the columnar particles in the lower layer 32 was 22 nm.

[0185] B. Phase-Shift Mask and Method of Making the Same

[0186] In order to manufacture the phase-shift mask 100 using the phase-shift mask blank 10 manufactured as described above, first, a photoresist film is applied on the etching mask film 40 of the phase-shift mask blank 10 using a resist coating apparatus.

[0187] Then, through a heating / cooling process, a photoresist film with a film thickness of 520 nm was formed.

[0188] Then, the photoresist film was patterned using a laser drawing device, and after a development / rinsing process, a resist film pattern having a hole pattern with a hole diameter of 1.5 μm was formed on the etching mask film.

[0189] Then, the etching mask film is wet-etched using a chromium etching solution containing ammonium cerium nitrate and perchloric acid, using the resist film pattern as a mask, thereby forming a first etching mask film pattern 40 a .

[0190] Then, the phase shift film 30 is wet-etched using the first etching mask film pattern 40a as a mask with a molybdenum silicide etching solution obtained by diluting a mixed solution of ammonium bifluoride and hydrogen peroxide with pure water, thereby forming a phase shift film pattern 30a. In order to make the cross-sectional shape vertical and to form a required fine pattern, the wet etching is performed with an overetching time of 110%. The appropriate etching time in Example 1 is 0.15 times the appropriate etching time in the comparative example described later, and the etching time can be greatly shortened.

[0191] Then, the resist film pattern is peeled off.

[0192] Then, a photoresist film is applied using a resist coating apparatus so as to cover the first etching mask film pattern 40 a .

[0193] Then, through a heating / cooling process, a photoresist film with a film thickness of 520 nm was formed.

[0194] Then, a photoresist film is drawn using a laser drawing device, and after a development / rinsing process, a second resist film pattern 60 for forming a light shielding band is formed on the first etching mask film pattern 40a.

[0195] Then, the first etching mask film pattern 40 a formed in the transfer pattern formation region was wet-etched using the second resist film pattern 60 as a mask with a chromium etching solution containing ammonium cerium nitrate and perchloric acid.

[0196] Then, the second resist film pattern 60 is peeled off.

[0197] Thus, a phase shift mask 100 is obtained, wherein on the transparent substrate 20, a phase shift film pattern 30a having an aperture of 1.5 μm is provided in the transfer pattern formation region, and a light shielding band consisting of a stacked structure of the phase shift film pattern 30a and the etching mask film pattern 40b is formed on the transparent substrate 20.

[0198] The cross section of the obtained phase shift mask was observed using a scanning electron microscope. The cross section of the phase shift film pattern is composed of the upper surface, lower surface and side surface of the phase shift film pattern. The angle of the cross section of the phase shift film pattern refers to the angle formed by the portion where the upper surface of the phase shift film pattern is connected to the side surface (upper side) and the portion where the side surface is connected to the lower surface (lower side). The cross section angle of the phase shift film pattern 30a of the obtained phase shift mask is greater than 75°, and has a good cross-sectional shape. The phase shift film pattern 30a formed in the phase shift mask of Example 1 has a cross-sectional shape that can fully exert the phase shift effect. By making the phase shift film 30 have a columnar structure in any layer of the upper layer 31 and the lower layer 32, the phase shift film pattern 30a forms a good cross-sectional shape, which can be considered to be due to the following mechanism. The phase shift film 30 has a columnar particle structure (columnar structure), and columnar particles extending in the film thickness direction are irregularly formed. In addition, the phase shift film 30 forms a relatively high density columnar particle portion and a relatively low density sparse portion in any layer of the upper layer 31 and the lower layer 32. Based on these facts, it can be considered that when the phase shift film 30 is patterned by wet etching, the etching liquid penetrates into the sparse portion in the phase shift film 30, so that it is easy to etch along the film thickness direction. On the other hand, since the columnar particles are irregularly formed in the direction perpendicular to the film thickness direction (the direction in the substrate surface) and the sparse portion in this direction is intermittently formed, it is difficult to etch in this direction and the side etching is suppressed. Therefore, the phase shift film pattern 30a obtains a good cross-sectional shape close to vertical. In addition, for the phase shift film pattern, no penetration is observed at the interface with the etching mask film pattern and the interface with the substrate. Therefore, for the exposure light containing the light in the wavelength range of 300nm or more and 500nm or less, more specifically, for the exposure light containing the composite light of i-line, h-line and g-line, a phase shift mask with excellent phase shift effect is obtained.

[0199] The line edge roughness of the phase shift film pattern in the phase shift mask obtained in Example 1 was measured and found to be 30 nm or less, satisfying the required level. The phase shift mask blank and the phase shift mask obtained in Example 1 were subjected to a cleaning test and found to satisfy the required cleaning resistance.

[0200] Therefore, when the phase shift mask of Example 1 is set on the mask stage of an exposure device and the resist film to be transferred to the display device is exposed, a fine pattern of less than 2.0 μm can be transferred with high accuracy.

[0201] It should be noted that the phase shift film pattern 30 a maintains the columnar structure of the phase shift film 30 , and the surface of the transparent substrate 20 exposed after the phase shift film 30 is removed is smooth, and the transmittance reduction caused by the rough surface of the transparent substrate 20 is negligible.

[0202] Example 2.

[0203] A. Phase-Shift Mask Blanks and Methods of Making Them

[0204] In order to manufacture the phase shift mask blank of Example 2, a synthetic quartz glass substrate of 1214 size (1220 mm×1400 mm) was prepared as a transparent substrate in the same manner as in Example 1.

[0205] The synthetic quartz glass substrate was transported to the chamber of the inline sputtering device by the same method as in Example 1. 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, with the sputtering gas pressure in the first chamber set to 1.6 Pa, a mixed gas (Ar: 18 sccm, N2: 13 sccm, NO: 4 sccm) of an inert gas composed of argon (Ar) and nitrogen (N2) and a nitric oxide gas (NO) as a reactive gas was introduced. Then, a sputtering power of 8.2 kW was applied to the first sputtering target containing molybdenum and silicon (molybdenum: silicon = 8:92), and a nitride oxide of molybdenum silicide containing molybdenum, silicon, oxygen and nitrogen was deposited on the main surface of the transparent substrate 20 by reactive sputtering, forming a lower layer 32 with a thickness of 140 nm. Then, the opening amount of the main valve of the vacuum pump connected to the first chamber was adjusted to set the sputtering gas pressure in the first chamber to 1.2 Pa, and the upper layer 31 with a thickness of 40 nm was formed on the lower layer 32 by reactive sputtering under the same conditions as the lower layer 32. In this way, the phase shift film 30 with a film thickness of 180 nm was formed.

[0206] Then, after the phase shift film is formed on the transparent substrate, it is taken out of the chamber and the surface of the phase shift film is cleaned with pure water at a temperature of 30 degrees and a cleaning time of 60 seconds.

[0207] Then, by the same method as in Example 1, an etching mask film 40 was formed.

[0208] Thus, the phase shift mask blank 10 in which the phase shift film 30 and the etching mask film 40 are formed on the transparent substrate 20 is obtained.

[0209] The transmittance and phase difference of the phase shift film of the obtained phase shift mask blank 10 (the surface of the phase shift film was cleaned with pure water) were measured using MPM-100 manufactured by Lasertec. The transmittance and phase difference of the phase shift film were measured using a substrate with a phase shift film (model substrate) in which a phase shift film 30 was formed on the main surface of a synthetic quartz glass substrate, and the substrate with a phase shift film was mounted on the same tray. The substrate with a phase shift film (model substrate) was taken out from the chamber before forming the etching mask film, and the transmittance and phase difference of the phase shift film 30 were measured. As a result, the transmittance was 45% (wavelength: 405nm), the phase difference was 188 degrees (wavelength: 405nm), and the back reflectivity was 0.7% (wavelength: 405nm).

[0210] In addition, the optical properties of the upper layer 31 and the lower layer 32 in the phase shift film 30 were measured using a spectroscopic ellipsometer (M-2000D manufactured by JA Woollam) in the same manner as in Example 1. As a result, the upper layer 31 had a refractive index of 2.30 and an extinction coefficient of 0.17. Furthermore, the lower layer 32 had a refractive index of 2.15 and an extinction coefficient of 0.11.

[0211] In addition, the obtained phase shift mask blank was subjected to composition analysis in the depth direction by X-ray photoelectron spectroscopy (XPS).

[0212] As a result, similarly to Example 1, in the phase shift film 30, except for the composition gradient region at the interface between the transparent substrate 20 and the phase shift film 30 and the composition gradient region at the interface between the phase shift film 30 and the etching mask film 40, the content of each constituent element in the depth direction is substantially constant, and the atomic ratio of molybdenum to silicon is 1:8, which is within the range of 1:3 or more and 1:15 or less. In addition, regarding the content of each constituent element, in the upper layer 31, Mo is 5 atomic%, Si is 40 atomic%, N is 47 atomic%, and O is 8 atomic%, and in the lower layer 32, Mo is 5 atomic%, Si is 40 atomic%, N is 45 atomic%, and O is 10 atomic%. In addition, the total content of oxygen and nitrogen as light elements is 55 atomic% in the upper layer 31 and 55 atomic% in the lower layer 32, both of which are 55 atomic%, both of which are within the range of 50 atomic% or more and 65 atomic% or less.

[0213] Next, a cross-sectional SEM observation was performed at a magnification of 80,000 times at the central position of the transfer pattern forming area of ​​the obtained phase shift mask blank 10, and it was confirmed that the phase shift film 30 had a columnar structure. That is, it was confirmed that the particles of the molybdenum silicide compound constituting the phase shift film 30 had a columnar particle structure extending in the film thickness direction of the phase shift film 30. It was also confirmed that the columnar particle structure of the phase shift film 30 was in a state where columnar particles in the film thickness direction were irregularly formed and the lengths of the columnar particles in the film thickness direction were inconsistent. It was also confirmed that the sparse portion of the phase shift film 30 was continuously formed in the film thickness direction. In addition, it was also confirmed that the average size of the columnar particles in the upper layer 31 of the phase shift film 30 was smaller than the average size of the columnar particles in the lower layer 32. The average size of the columnar particles in the upper layer 31 was 15 nm, and the average size of the columnar particles in the lower layer 32 was 25 nm.

[0214] B. Phase-Shift Mask and Method of Making the Same

[0215] Using the phase shift mask blank manufactured as described above, a phase shift mask having a phase shift film pattern with a hole diameter of 1.5 μm was manufactured by the same method as in Example 1. In order to make the cross-sectional shape vertical and to form the required fine pattern, the wet etching of the phase shift film 30 was performed with an overetching time of 110%. The appropriate etching time in Example 2 is 0.07 times the appropriate etching time in the comparative example described later, and the etching time can be greatly shortened.

[0216] The cross section of the obtained phase shift mask was observed using a scanning electron microscope. The cross section angle of the phase shift film pattern 30a of the phase shift mask was 75° or more, and had a good cross-sectional shape. In addition, for the phase shift film pattern, no penetration was observed at the interface with the etching mask film pattern and the interface with the substrate. Therefore, for exposure light including light in the wavelength range of 300nm or more and 500nm or less, more specifically, for exposure light including composite light of i-line, h-line and g-line, a phase shift mask having an excellent phase shift effect was obtained.

[0217] The line edge roughness of the phase shift film pattern in the phase shift mask obtained in Example 2 was measured and found to be 30 nm or less, satisfying the required level. The phase shift mask blank and the phase shift mask obtained in Example 2 were subjected to a cleaning test and found to satisfy the required cleaning resistance.

[0218] Therefore, when the phase shift mask of Example 2 is set on the mask stage of an exposure device and the resist film to be transferred to the display device is exposed, a fine pattern of less than 2.0 μm can be transferred with high accuracy.

[0219] The phase shift film pattern 30 a maintains the columnar structure of the phase shift film 30 , and the surface of the transparent substrate 20 exposed after the phase shift film 30 is removed is smooth, and the transmittance reduction caused by the rough surface of the transparent substrate 20 is negligible.

[0220] It should be noted that, in the above-mentioned embodiments, the case where molybdenum is used as the transition metal is described, but the same effects as those described above can be obtained in the case of other transition metals.

[0221] In addition, in the above-mentioned embodiments, examples of phase shift mask blanks and phase shift masks for display device manufacturing are described, but the invention is not limited thereto. The phase shift mask blanks and phase shift masks of the present invention can also be applied to semiconductor device manufacturing, MEMS manufacturing, printed circuit board applications, etc. In addition, the present invention can also be applied to binary mask blanks having a light shielding film as a thin film for pattern formation and binary masks having a light shielding film pattern.

[0222] In addition, in the above-mentioned embodiment, an example in which the size of the transparent substrate is 1214 size (1220mm×1400mm×13mm) is described, but it is not limited to this. In the case of a phase shift mask blank for display device manufacturing, a large size transparent substrate can be used, and the size of the transparent substrate is a side length of 300mm or more. The size of the transparent substrate used in the phase shift mask blank for display device manufacturing is, for example, 330mm×450mm or more and 2280mm×3130mm or less.

[0223] In addition, in the case of phase-shift mask blanks for semiconductor device manufacturing, MEMS manufacturing, and printed circuit board applications, a small-sized transparent substrate can be used, the size of which is a side length of 9 inches or less. The size of the transparent substrate used in the phase-shift mask blanks for the above-mentioned purposes is, for example, 63.1 mm × 63.1 mm or more and 228.6 mm × 228.6 mm or less. Typically, 6025 size (152 mm × 152 mm) and 5009 size (126.6 mm × 126.6 mm) are used for semiconductor manufacturing and MEMS manufacturing, and 7012 size (177.4 mm × 177.4 mm) and 9012 size (228.6 mm × 228.6 mm) are used for printed circuit boards.

[0224] Comparative Example 1.

[0225] A. Phase-Shift Mask Blanks and Methods of Making Them

[0226] In order to manufacture the phase shift mask blank of Comparative Example 1, a synthetic quartz glass substrate of 1214 size (1220 mm×1400 mm) was prepared as a transparent substrate in the same manner as in Example 1.

[0227] The synthetic quartz glass substrate was transported to the chamber of the inline sputtering device by the same method as in Example 1. Then, a mixed gas of argon (Ar) gas and nitrogen (N2) gas (Ar: 30 sccm, N2: 30 sccm) was introduced while the sputtering gas pressure in the first chamber was set to 0.5 Pa. Then, a sputtering power of 7.6 kW was applied to the first sputtering target containing molybdenum and silicon (molybdenum: silicon = 1:9), and a nitride of molybdenum silicide containing molybdenum, silicon and nitrogen was deposited on the main surface of the transparent substrate by reactive sputtering. Thus, a phase shift film with a film thickness of 144 nm was formed.

[0228] Then, by the same method as in Example 1, an etching mask film was formed.

[0229] Thus, a phase shift mask blank in which a phase shift film and an etching mask film are formed on a transparent substrate is obtained.

[0230] The transmittance and phase difference of the phase shift film of the obtained phase shift mask blank were measured using MPM-100 manufactured by Lasertec. The transmittance and phase difference of the phase shift film were measured using a substrate with a phase shift film (model substrate) formed on the main surface of a synthetic quartz glass substrate, and the substrate with a phase shift film was mounted on the same tray. The substrate with a phase shift film (model substrate) was taken out of the chamber before forming the etching mask film, and the transmittance and phase difference of the phase shift film were measured. The results showed that the transmittance was 29% (wavelength: 405nm), the phase difference was 172 degrees (wavelength: 405nm), and the back reflectivity was 11% (wavelength: 405nm).

[0231] In addition, the obtained phase shift mask blank was subjected to composition analysis in the depth direction by X-ray photoelectron spectroscopy (XPS). As a result, in the phase shift film 30, except for the composition gradient region at the interface between the transparent substrate 20 and the phase shift film 30 and the composition gradient region at the interface between the phase shift film 30 and the etching mask film 40, the content of each constituent element in the depth direction was basically constant, with Mo being 8 atomic %, Si being 39 atomic %, N being 52 atomic %, and O being 1 atomic %. In addition, the atomic ratio of molybdenum to silicon was 1:4.9, which was within the range of 1:3 or more and 1:15 or less. In addition, the total content of oxygen, nitrogen, and carbon as light elements was 53 atomic %, which was within the range of 50 atomic % or more and 65 atomic % or less.

[0232] Next, a cross-sectional SEM observation was performed at a magnification of 80,000 times at the center of the transfer pattern formation region of the obtained phase shift mask blank 10. As a result, no columnar structure was confirmed in the phase shift film, and it was confirmed that it was an ultrafine crystal structure or an amorphous structure.

[0233] B. Phase-Shift Mask and Method of Making the Same

[0234] Using the phase shift mask blank manufactured as described above, a phase shift mask was manufactured by the same method as in Example 1. In order to make the cross-sectional shape vertical and to form the required fine pattern, the wet etching of the phase shift mask was performed with an overetching time of 110%. The appropriate etching time in Comparative Example 1 was 142 minutes, which was a very long time.

[0235] The surface of the transparent substrate 20 exposed after the phase shift film 30 is removed is rough and appears cloudy when observed with the naked eye. Therefore, the decrease in transmittance due to the rough surface of the transparent substrate 20 is significant.

[0236] Therefore, it is predicted that when the phase shift mask of Comparative Example 1 is set on the mask stage of an exposure device and the resist film to be transferred to the display device is exposed, a fine pattern smaller than 2.0 μm cannot be transferred.

Claims

1. A photomask blank having a pattern-forming thin film on a transparent substrate, wherein: The photomask blank is an original plate for forming a photomask, and the photomask is a photomask having a transfer pattern on the transparent substrate obtained by wet etching the pattern-forming thin film. The pattern-forming thin film contains a transition metal and silicon. The transition metal is any metal selected from molybdenum, tantalum, tungsten, titanium and zirconium. The atomic ratio of the transition metal to the silicon contained in the pattern-forming thin film is transition metal:silicon=1:3 or more and 1:15 or less, The pattern-forming film comprises an upper layer and a lower layer, The upper layer and the lower layer both have a columnar structure. The columnar structure is formed by forming columnar particles extending in the film thickness direction in the entire surface of the transparent substrate and forming a sparse portion having a relatively low density compared to the columnar particles. An average size of the columnar particles in the upper layer is smaller than an average size of the columnar particles in the lower layer.

2. The photomask blank according to claim 1, wherein: The pattern-forming thin film contains at least nitrogen or oxygen.

3. The photomask blank according to claim 1, wherein: The transition metal is molybdenum.

4. The photomask blank according to claim 1, wherein: The pattern-forming thin film is a phase shift film having the following optical properties: a transmittance of a representative wavelength of exposure light of 1% to 80% and a phase difference of 160° to 200°. 5 . The photomask blank according to claim 1 , further comprising an etching mask film having a different etching selectivity with respect to the pattern forming thin film on the pattern forming thin film.

6. The photomask blank according to claim 5, wherein: The etching mask film is formed of a material containing chromium but substantially containing no silicon.

7. A method for manufacturing a photomask blank, the method comprising: A pattern-forming thin film containing transition metal and silicon is formed on a transparent substrate by a sputtering method. The pattern-forming thin film is formed in a film forming chamber using a transition metal silicide target containing a transition metal and silicon, and a sputtering gas pressure in the film forming chamber to which a sputtering gas is supplied is 0.8 Pa or more and 3.0 Pa or less, The atomic ratio of the transition metal to silicon in the transition metal silicide target is transition metal:silicon=1:3 or more and 1:15 or less, The transition metal is any metal selected from molybdenum, tantalum, tungsten, titanium and zirconium. The pattern-forming film comprises an upper layer and a lower layer, The upper layer and the lower layer both have a columnar structure. The columnar structure is formed by forming columnar particles extending in the film thickness direction in the entire surface of the transparent substrate and forming a sparse portion having a relatively low density compared to the columnar particles. The sputtering gas pressure in the film forming chamber when forming the upper layer is lower than the sputtering gas pressure in the film forming chamber when forming the lower layer. The sputtering gas pressure when forming the upper layer is 0.8 Pa or more and 1.5 Pa or less, and the sputtering gas pressure when forming the lower layer is 1.2 Pa or more and 3.0 Pa or less.

8. The method for manufacturing a photomask blank according to claim 7, wherein: An etching mask film is formed on the pattern-forming thin film using a sputtering target made of a material having a different etching selectivity with respect to the pattern-forming thin film.

9. The method for manufacturing a photomask blank according to claim 8, wherein: The pattern-forming thin film and the etching mask film are formed using an in-line sputtering apparatus.

10. A method for manufacturing a photomask, the method comprising: A step of preparing the photomask blank according to any one of claims 1 to 4, or a photomask blank manufactured by the method for manufacturing a photomask blank according to claim 7; as well as A step of forming a resist film on the pattern-forming thin film, and wet-etching the pattern-forming thin film using a resist film pattern formed by the resist film as a mask to form a transfer pattern on the transparent substrate.

11. A method for manufacturing a photomask, the method comprising: A step of preparing the photomask blank according to claim 5 or 6, or a photomask blank manufactured by the method for manufacturing a photomask blank according to claim 8 or 9; A step of forming a resist film on the etching mask film, and wet-etching the etching mask film using a resist film pattern formed by the resist film as a mask to form an etching mask film pattern on the pattern-forming thin film; as well as A step of wet-etching the pattern-forming thin film using the etching mask film pattern as a mask to form a transfer pattern on the transparent substrate.

12. A method for manufacturing a display device, the method comprising: An exposure step of placing the photomask obtained by the method for producing a photomask according to claim 10 or 11 on a mask stage of an exposure device, and transferring the transfer pattern formed on the photomask to a resist formed on a display device substrate by exposure.

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