KR20230065208A - Photomask blank, method for manufacturing photomask, and method for manufacturing display device - Google Patents

Abstract

The present invention provides a photomask blank which can shorten an over-etching time, when a transfer pattern is formed on a thin film for forming a pattern by wet etching, and can form a transfer pattern with a good cross-sectional shape. The photomask blank, as a photomask blank having a thin film for forming a pattern on a transparent substrate, is an original plate for forming a photomask with a transfer pattern on a transparent substrate by performing wet etching on a thin film for forming a pattern. The thin film for forming a pattern contains transition metal and silicon, and the thin film for forming a pattern has a columnar structure.

Description

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

The present invention relates to a photomask blank, a method for manufacturing a photomask blank, a method for manufacturing a photomask, and a display device.

BACKGROUND ART [0002] In recent years, in display devices such as FPD (Flat Panel Display) typified by LCD (Liquid Crystal Display), high-definition and high-speed display are progressing rapidly along with large screens and wide viewing angles. One of the elements necessary for this high-definition and high-speed display is the production of electronic circuit patterns such as fine elements and wires with high dimensional accuracy. Photolithography is often used for patterning electronic circuits for display devices. For this reason, a photomask such as a phase shift mask or binary mask for manufacturing a display device in which fine and high-precision patterns are formed is required.

For example, Patent Document 1 discloses a phase shift mask blank provided with a phase shift film on a transparent substrate. In this mask blank, the phase shift film has a reflectance of 35% or less and a reflectance of 1% to 40% for exposure light of complex wavelengths including i-line (365 nm), h-line (405 nm), and g-line (436 nm). It is a metal silicide compound containing at least one light element material of oxygen (O), nitrogen (N), and carbon (C) to have a transmittance of % and to form a steep inclination of the pattern cross section during pattern formation. The metal silicide compound is formed by injecting a reactive gas and an inert gas containing the light element material at a ratio of 0.5:9.5 to 4:6.

Further, Patent Document 2 discloses a phase shift mask blank comprising a transparent substrate, a light semitransmissive film having a property of changing the phase of exposure light and composed of a metal silicide-based material, and an etching mask film composed of a chromium-based material. has been In this phase shift mask blank, a composition gradient region is formed at the interface between the light semitransmissive film and the etching mask film. In the composition gradient region, the ratio of the component that slows down the wet etching rate of the light semitransmissive film increases in the depth direction. And the content of oxygen in the composition gradient region is 10 atomic% or less.

Korean Registered Patent No. 1801101 Patent No. 6101646

As a phase shift mask used for recent high-precision (1000 ppi or more) panel production, it is a phase shift mask in order to enable high-resolution pattern transfer, and it has a fine hole diameter of 6 μm or less and a line width of 4 μm or less. A phase shift mask in which a phase shift film pattern is formed is required. Specifically, a phase shift mask in which a fine phase shift film pattern with a hole diameter of 1.5 μm is formed is required.

In addition, in order to realize higher resolution pattern transfer, a phase shift mask blank having a phase shift film having a transmittance to exposure light of 15% or more and a phase shift mask having a phase shift film pattern having a transmittance to exposure light of 15% or more are formed. is being demanded In addition, in the cleaning resistance (chemical characteristics) of the phase shift mask blank or phase shift mask, the phase shift film or phase shift film pattern having a cleaning resistance in which the change in optical characteristics due to film reduction or surface composition change is suppressed. A phase shift mask blank with a shift film and a phase shift mask with a phase shift film pattern having cleaning resistance are required.

In order to satisfy the requirement of transmittance to exposure light and the requirement of cleaning resistance, it is necessary to increase the ratio of silicon in the atomic ratio of metal to silicon in the metal silicide compound (metal silicide-based material) constituting the phase shift film. Although effective, there was a problem that the wet etching rate was greatly slowed down (wet etching time was prolonged), damage to the substrate by the wet etching solution occurred, and the transmittance of the transparent substrate decreased.

In addition, in a binary mask blank provided with a light-shielding film containing a transition metal and silicon, when forming a light-shielding pattern on the light-shielding film by wet etching, there is a demand regarding cleaning resistance, and there is a problem similar to the above.

Therefore, the present invention has been made in order to solve the above problems, and an object of the present invention is to form a transfer pattern on a thin film for pattern formation such as a phase shift film or a light-shielding film containing a transition metal and silicon by wet etching. To provide a photomask blank capable of shortening the wet etching time and forming a transfer pattern having a good cross-sectional shape, a method for manufacturing a photomask blank, a method for manufacturing a photomask, and a method for manufacturing a display device.

The present inventors intensively studied measures for solving these problems. First, the atomic ratio of the transition metal to silicon in the thin film for pattern formation is set to a material in which the transition metal:silicon is 1:3 or more, and the wet etching time by the wet etchant in the thin film for pattern formation is shortened, The thin film for pattern formation was formed by adjusting the oxygen gas included in the sputtering gas introduced into the film formation chamber so that the thin film for pattern formation contained a large amount of oxygen (O). As a result, although the wet etching rate for forming the transfer pattern is increased, in the phase shift film in the phase shift mask blank, the refractive index with respect to exposure light is lowered, so that the desired phase difference (eg 180°) can be obtained. The required film thickness to obtain becomes thick. Further, in the light shielding film in the binary mask blank, since the extinction coefficient with respect to exposure light decreases, the required film thickness for obtaining desired light shielding performance (eg, optical density (OD) of 3 or more) becomes thick. . The increase in the film thickness of the thin film for pattern formation is disadvantageous in pattern formation by wet etching, and since the film thickness increases, there is a limit as an effect of shortening the wet etching time. On the other hand, if the above-mentioned transition metal to silicon atomic ratio (transition metal: silicon = 1:3 or more) has an advantage such as increasing the cleaning resistance of the thin film for pattern formation, in this respect also, the above-mentioned transition metal It is not desirable to deviate from the composition ratio of silicon and silicon.

Then, the present inventor changed his idea and studied changing the film structure by adjusting the pressure of the sputtering gas in the film formation chamber. When forming a thin film for pattern formation on a substrate, it is usual to set the sputtering gas pressure in the film forming chamber to 0.1 to 0.5 Pa. However, the present inventor intentionally made the sputtering gas pressure higher than 0.5 Pa to form a thin film for pattern formation. In addition, the thin film for pattern formation is formed at a sputtering pressure of 0.7Pa or more and 3.0Pa or less, preferably at a sputtering gas pressure of 0.8Pa or more and 3.0Pa or less, so that it has suitable properties as a thin film and is suitable for use as a thin film for pattern formation. It has been found that when the transfer pattern is formed by wet etching, the etching time can be greatly shortened, and a transfer pattern having a good cross-sectional shape can be formed. And the thin film for pattern formation formed in this way had a columnar structure which is not seen in the normal thin film for pattern formation. The present invention has been made as a result of the above-mentioned intensive studies, and has the following configurations.

(Configuration 1) A photomask blank having a thin film for pattern formation on a transparent substrate,

The photomask blank is an original plate for forming a photomask having a transfer pattern on the transparent substrate by wet etching the thin film for pattern formation,

The thin film for pattern formation contains a transition metal and silicon,

The photomask blank, characterized in that the thin film for pattern formation has a columnar structure.

(Configuration 2) The thin film for pattern formation,

Image data of 64 pixels in height x 256 pixels in width for an area including the central portion in the thickness direction of the thin film for pattern formation, with respect to an image obtained by observing a cross section of the photomask blank with a scanning electron microscope at a magnification of 80000 times. , and in the spatial frequency spectrum distribution obtained by Fourier transforming the image data, there is a spatial frequency spectrum having a signal intensity of 1.0% or more with respect to the maximum signal intensity corresponding to the origin of the spatial frequency. The photomask blank described in 1.

(Configuration 3) In the configuration 2, in the thin film for pattern formation, the signal having the signal intensity of 1.0% or more is at a spatial frequency 2.0% or more away from the origin of the spatial frequency when the maximum spatial frequency is 100%. Photomask blanks as described.

(Configuration 4) The photomask according to any one of Configurations 1 to 3, wherein an atomic ratio of the transition metal and the silicon contained in the thin film for pattern formation is transition metal:silicon = 1:3 or more and 1:15 or less. blank.

(Configuration 5) The photomask blank according to any one of Configurations 1 to 4, wherein the thin film for pattern formation contains at least nitrogen or oxygen.

(Configuration 6) The thin film for pattern formation contains nitrogen, and the atomic ratio of the transition metal and the silicon contained in the thin film for pattern formation is transition metal:silicon = 1:3 or more and 1:15 or less,

The photomask blank according to configuration 5, wherein the thin film for pattern formation has an indentation hardness derived by a nanoindentation method of 18 GPa or more and 23 GPa or less.

(Configuration 7) The photomask blank according to Configuration 6, wherein the nitrogen content is 35 atomic % or more and 60 atomic % or less.

(Configuration 8) The photomask blank according to any one of Configurations 1 to 7, wherein the transition metal is molybdenum.

(Configuration 9) The thin film for pattern formation is a phase shift film provided with optical characteristics such as a transmittance of 1% or more and 80% or less and a phase difference of 160° or more and 200° or less with respect to a representative wavelength of exposure light. The photomask blank described in any one of 8.

(Configuration 10) The photomask blank according to any one of Configurations 1 to 9, wherein an etching mask film having a different etching selectivity with respect to the pattern forming thin film is provided on the pattern forming thin film.

(Configuration 11) The photomask blank according to Configuration 10, wherein the etching mask film is made of a material containing chromium and substantially no silicon.

(Configuration 12) A method for producing a photomask blank in which a thin film for pattern formation containing a transition metal and silicon is formed on a transparent substrate by a sputtering method,

The thin film for pattern formation is formed using a transition metal silicide target containing a transition metal and silicon in a film formation chamber, and a sputtering gas pressure in the film formation chamber supplied with a sputtering gas is 0.7 Pa or more and 3.0 Pa or less. A method for manufacturing a photomask blank.

(Configuration 13) The method for manufacturing a photomask blank according to configuration 12, wherein the transition metal:silicon atomic ratio of the transition metal silicide target is transition metal:silicon = 1:3 or more and 1:15 or less.

(Configuration 14) The photomask blank according to Configuration 12 or 13, wherein an etching mask film is formed on the thin film for pattern formation using a sputter target made of a material having a different etching selectivity with respect to the thin film for pattern formation. manufacturing method.

(Configuration 15) The photomask blank manufacturing method according to configuration 14, wherein the thin film for pattern formation and the etching mask film are formed using an in-line sputtering device.

(Configuration 16) A step of preparing a photomask blank manufactured by the photomask blank according to any one of Configurations 1 to 9 or the photomask blank manufacturing method according to Configuration 12 or 13;

Forming a resist film on the thin film for pattern formation, wet etching the thin film for pattern formation using the resist film pattern formed from the resist film as a mask, and forming a transfer pattern on the transparent substrate. Method for manufacturing a photomask characterized by

(Configuration 17) a step of preparing a photomask blank manufactured by the photomask blank described in Configuration 10 or 11 or the photomask blank manufacturing method described in Configuration 14 or 15;

forming a resist film on the etching mask film, wet-etching the etching mask film using the resist film pattern formed from the resist film as a mask, and forming an etching mask film pattern on the pattern forming thin film;

and wet-etching the thin film for pattern formation using the etching mask film pattern as a mask, and forming a transfer pattern on the transparent substrate.

(Configuration 18) A photomask obtained by the photomask manufacturing method described in Configuration 16 or 17 is placed on a mask stage of an exposure apparatus, and the transfer pattern formed on the photomask is applied to a resist formed on a display device substrate. A manufacturing method of a display device characterized by having an exposure step of performing exposure transfer.

In addition, the present inventors studied adjusting the pressure of the sputtering gas in the film formation chamber and changing the film structure, and found the following other configurations. As described above, the present inventor intentionally made the sputtering gas pressure higher than 0.5 Pa to form a thin film for pattern formation. In addition, by forming a thin film for pattern formation at a sputtering gas pressure of 0.7 Pa or more, the etching time can be significantly shortened, a transfer pattern having a good cross-sectional shape can be formed, and the surface roughness of the transparent substrate can be suppressed. found out On the other hand, it has been found that if the sputtering gas pressure during film formation is excessively increased, sufficient cleaning resistance cannot be obtained in the thin film for pattern formation. As a result of intensive studies, the inventors of the present invention formed a thin film for pattern formation at a sputtering gas pressure of 0.7 Pa or more and 2.4 Pa or less, thereby forming a transfer pattern having suitable properties as a thin film for pattern formation and having a good cross-sectional shape. It has been found that the surface roughness of the transparent substrate can be suppressed and the cleaning resistance of the thin film for pattern formation can be improved.

And, the present inventors further explored the physical index of the thin film for pattern formation having such excellent characteristics. As a result, it was found that there is a correlation between the indentation hardness of the thin film for pattern formation and the wet etching rate. As a result of further intensive study on this point, if the indentation hardness derived by the nanoindentation method is 18 GPa or more and 23 GPa or less, in addition to having suitable properties as a thin film for pattern formation, the thin film for pattern formation is wetted with a transfer pattern. It has been found that, when formed by etching, a transfer pattern having a good cross-sectional shape can be formed, and surface roughness of a transparent substrate can be suppressed, while cleaning resistance of a thin film for pattern formation can be improved.

(Other configuration 1) A photomask blank having a thin film for pattern formation on a transparent substrate,

The photomask blank is an original plate for forming a photomask having a transfer pattern on the transparent substrate by wet etching the thin film for pattern formation,

The thin film for pattern formation contains a transition metal, silicon, and nitrogen, and the atomic ratio of the transition metal and the silicon contained in the thin film for pattern formation is transition metal:silicon = 1:3 or more and 1:15. below,

The thin film for pattern formation is a photomask blank, characterized in that the indentation hardness derived by the nanoindentation method is 18 GPa or more and 23 GPa or less.

(Other configuration 2) The photomask blank according to another configuration 1, wherein the transition metal is molybdenum.

(Other configuration 3) The photomask blank according to another configuration 1 or 2, wherein the nitrogen content is 35 atomic% or more and 60 atomic% or less.

(Other configuration 4) The thin film for pattern formation is a phase shift film provided with optical characteristics such as a transmittance of 1% or more and 80% or less and a phase difference of 160° or more and 200° or less with respect to a representative wavelength of exposure light. The photomask blank described in any one of 1 to 3.

(Other configuration 5) The photomask blank according to any one of configurations 1 to 4, wherein an etching mask film having a different etching selectivity with respect to the thin film for pattern formation is provided on the thin film for pattern formation.

(Other configuration 6) The photomask blank according to another configuration 5, wherein the etching mask film is made of a material containing chromium and substantially no silicon.

(Other configuration 7) Step of preparing the photomask blank according to any of the other configurations 1 to 4;

A step of forming a resist film on the thin film for pattern formation, wet etching the thin film for pattern formation using the resist film pattern formed from the resist film as a mask, and forming a transfer pattern on the transparent substrate. A method for manufacturing a photomask.

(Other configuration 8) a step of preparing the photomask blank described in the other configuration 5 or 6;

forming a resist film on the etching mask film, wet-etching the etching mask film using the resist film pattern formed from the resist film as a mask, and forming an etching mask film pattern on the pattern forming thin film;

and wet-etching the thin film for pattern formation using the etching mask film pattern as a mask, and forming a transfer pattern on the transparent substrate.

(Other configuration 9) The photomask obtained by the photomask manufacturing method described in the other configuration 7 or 8 is loaded on a mask stage of an exposure apparatus, and the transfer pattern formed on the photomask is applied to a resist formed on a display device substrate. A manufacturing method of a display device characterized by comprising an exposure step of exposing and transferring the image to the display device.

According to the photomask blank or the method for manufacturing a photomask blank according to the present invention, when forming a fine transfer pattern required by wet etching the thin film for pattern formation, the thin film for pattern formation is silicon-rich from the point of view of cleaning resistance, etc. A photomask blank capable of forming a transfer pattern having a good cross-sectional shape in a short etching time without reducing the transmittance of the transparent substrate due to damage to the substrate by a wet etching solution even when a metal silicide compound is used You can get it. In addition, according to the photomask blank according to another configuration of the present invention, when forming a fine transfer pattern required by wet etching a thin film for a transfer pattern, a transfer pattern having a good cross-sectional shape can be formed, and the transparent substrate A photomask blank capable of suppressing surface roughness and improving cleaning resistance of a thin film for a transfer pattern can be obtained.

Further, according to the method for manufacturing a photomask according to the present invention, a photomask is manufactured using the photomask blank described above. For this reason, even when the thin film for pattern formation is made of a silicon-rich metal silicide compound from the point of view of cleaning resistance or the like, there is no decrease in the transmittance of the transparent substrate due to damage to the substrate by the wet etching solution, and the transfer accuracy is good. A photomask having a transfer pattern can be manufactured. This photomask can respond to miniaturization of line and space patterns and contact holes. In addition, according to the photomask manufacturing method according to another configuration of the present invention, a transfer pattern having a good cross-sectional shape can be formed, surface roughness of the transparent substrate can be suppressed, and the cleaning resistance of the thin film for the transfer pattern can be improved. A photomask that can be increased can be manufactured.

Further, according to the display device manufacturing method according to the present invention, a display device is manufactured using a photomask manufactured using the photomask blank described above or a photomask obtained by the photomask manufacturing method described above. For this reason, a display device having a fine line-and-space pattern or contact hole can be manufactured.

1 is a schematic diagram showing the film configuration of a phase shift mask blank according to Embodiment 1. FIG.
2 is a schematic diagram showing the film configuration of a phase shift mask blank according to Embodiment 2;
3 is a schematic diagram showing a manufacturing process of a phase shift mask according to Embodiment 3;
4 is a schematic diagram showing a manufacturing process of a phase shift mask according to Embodiment 4;
Fig.5 (a) is an enlarged photograph (image data) of the center part of the thickness direction of a phase shift film in the cross-sectional SEM image of the phase shift mask blank of Example 1.
(b) is the result of Fourier transformation of the enlarged photograph (image data) of (a).
6 is a dark field plane STEM photograph of the phase shift film in the phase shift mask blank of Example 1.
7 is a cross-sectional photograph of the phase shift mask of Example 1.
The same figure (a) of FIG. 8 is an enlarged photograph (image data) of the center part of the thickness direction of the phase shift film in the cross-sectional SEM image of the phase shift mask blank of Example 2. The same figure (b) is the result of Fourier transformation of the enlarged photograph (image data) of the same figure (a).
9 is a cross-sectional photograph of the phase shift mask of Example 2.
The same figure (a) of FIG. 10 is an enlarged photograph (image data) of the center part of the thickness direction of the phase shift film in the cross-sectional SEM image of the phase shift mask blank of Example 3. The same figure (b) is the result of Fourier transformation of the enlarged photograph (image data) of the same figure (a).
11 is a cross-sectional photograph of the phase shift mask of Example 3.
The same figure (a) of FIG. 12 is an enlarged photograph (image data) of the center part of the thickness direction of the phase shift film in the cross-sectional SEM image of the phase shift mask blank of Comparative Example 1. The same figure (b) is the result of Fourier transformation of the enlarged photograph (image data) of the same figure (a).
13 is a cross-sectional photograph of a phase shift mask of Comparative Example 1.
Fig. 14 is a graph showing the relationship between the etching rate, the sputtering gas pressure, and the indentation hardness in the phase shift films of the phase shift masks of other Examples 1 to 4 and Comparative Examples 1 and 2.

Embodiment 1. 2.

Embodiments 1 and 2 describe phase shift mask blanks. In the phase shift mask blank of Embodiment 1, a phase shift mask having a phase shift film pattern is formed on a transparent substrate by wet etching the phase shift film using an etching mask film pattern in which a desired pattern is formed on the etching mask film as a mask. It is a disc for Further, the phase shift mask blank of Embodiment 2 is for forming a phase shift film having a phase shift film pattern on a transparent substrate by wet etching the phase shift film using a resist film pattern in which a desired pattern is formed on the resist film as a mask. it is a disc

1 is a schematic diagram showing the film configuration of a phase shift mask blank 10 according to Embodiment 1. FIG.

The phase shift mask blank 10 shown in FIG. 1 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. ) is provided.

2 is a schematic diagram showing the film configuration of the phase shift mask blank 10 according to the second embodiment.

The phase shift mask blank 10 shown in FIG. 2 is equipped with the transparent substrate 20 and the phase shift film 30 formed on the transparent substrate 20.

Hereinafter, the transparent substrate 20, the phase shift film 30, and the etching mask film 40 which constitute the phase shift mask blank 10 of Embodiment 1 and Embodiment 2 are demonstrated.

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

The phase shift film 30 is composed of a transition metal and a silicon-containing transition metal silicide-based material. As the transition metal, molybdenum (Mo), tantalum (Ta), tungsten (W), titanium (Ti), zirconium (Zr) and the like are suitable, and molybdenum (Mo) is particularly preferable.

Moreover, it is preferable that the phase shift film 30 contains at least nitrogen or oxygen. In the transition metal silicide-based material, since oxygen, which is a light element component, has an effect of lowering the extinction coefficient compared to nitrogen, which is a light element component, other light element components (such as nitrogen) for obtaining a desired transmittance While being able to reduce a content rate, the reflectance of the front surface of the phase shift film 30 and the back surface can also be reduced effectively. In addition, in the transition metal silicide-based material, nitrogen as a light element component has an effect of not lowering the refractive index compared to oxygen, which is also a light element component, so that the film thickness for obtaining a desired phase difference can be reduced. there is. Moreover, as for the total content rate of the light element component containing oxygen and nitrogen contained in the phase shift film 30, 40 atomic% or more is preferable. More preferably, it is 40 atomic% or more and 70 atomic% or less, and 50 atomic% or more and 65 atomic% or less are preferable. In addition, when oxygen is contained in the phase shift film 30, as for the content rate of oxygen, it is preferable in defect quality and chemical-resistance that it is more than 0 atomic% and 40 atomic% or less.

Examples of the transition metal silicide-based material include nitrides of transition metal silicides, oxides of transition metal silicides, oxynitrides of transition metal silicides, and oxynitride carbides of transition metal silicides. In addition, if the transition metal silicide-based material is a molybdenum silicide-based material (MoSi-based material), zirconium silicide-based material (ZrSi-based material), or molybdenum zirconium silicide-based material (MoZrSi-based material), an excellent pattern cross-sectional shape by wet etching can be obtained. It is preferable from the point of being easy to obtain, and it is especially preferable if it is a molybdenum silicide-type material (MoSi-type material).

In addition to the oxygen and nitrogen described above, the phase shift film 30 may contain other light element components such as carbon and helium for the purpose of reducing film stress and controlling the wet etching rate.

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

The phase shift film 30 can be formed by sputtering.

It is preferable that this phase shift film 30 has a columnar structure. This columnar structure can confirm the phase shift film 30 by cross-sectional SEM observation. That is, in the columnar structure in the present invention, the particles of the transition metal silicide compound containing the transition metal and silicon constituting the phase shift film 30 are formed in the film thickness direction of the phase shift film 30 (the particles are deposited It refers to the state of having a columnar particle structure extending toward the In the present application, particles having a length in the film thickness direction longer than a length in the vertical direction are used as columnar particles. That is, in the phase shift film 30 , columnar particles extending in the film thickness direction are formed over the surface of the transparent substrate 20 . Further, in the phase shift film 30, by adjusting the film formation conditions (such as sputtering pressure), a small portion having a relatively lower density than the main phase particles (hereinafter sometimes simply referred to as a "small portion") is also formed. . Further, in order to effectively suppress side etching during wet etching and further improve the cross-sectional shape of the pattern, the phase shift film 30 has a preferred form of the columnar structure of the phase shift film 30 extending in the film thickness direction. It is preferable that the columnar particles are irregularly formed in the film thickness direction. More preferably, it is preferable that the length of the columnar particle of the phase shift film 30 is uneven in the film thickness direction. And it is preferable that the small part of the phase shift film 30 is continuously formed in the film thickness direction. In addition, it is preferable that small portions of the phase shift film 30 are formed intermittently in a direction perpendicular to the film thickness direction. As a preferable form of the columnar structure of the phase shift film 30, it can represent as follows using the index which carried out the Fourier transform about the image obtained by the said cross-section SEM observation. That is, the columnar structure of the phase shift film 30 is a region including the central portion in the thickness direction of the phase shift film 30 with respect to an image obtained by cross-sectional SEM observation of a cross section of the phase shift mask blank at a magnification of 80000 times. , image data of 64 pixels in height x 256 pixels in width is extracted, and the spatial frequency spectrum obtained by Fourier transform of this image data has a signal intensity of 1.0% or more with respect to the maximum signal intensity corresponding to the origin of the spatial frequency. state is preferred. When the phase shift film 30 has the above-described columnar structure, the wet etching liquid easily penetrates in the film thickness direction of the phase shift film 30 at the time of wet etching using the wet etching liquid, so the wet etching rate is increased, and the wet etching time can be drastically reduced. Therefore, even if the phase shift film 30 is a metal silicide compound rich in silicon, there is no decrease in transmittance of the transparent substrate due to damage to the substrate by the wet etching solution. In addition, since the phase shift film 30 has a columnar structure extending in the film thickness direction, side etching at the time of wet etching is suppressed, so the pattern cross-sectional shape also becomes good.

Further, the phase shift film 30 is such that a signal having an intensity signal of 1.0% or more of the maximum signal intensity of the spatial frequency spectrum distribution obtained by Fourier transform is 2.0% or more from the origin of the spatial frequency when the maximum spatial frequency is 100%. It is desirable to be at a distant spatial frequency. The fact that signals having an intensity signal of 1.0% or more of the maximum signal intensity are separated by 2.0% or more indicates that a spatial frequency component higher than a certain level is included. That is, the state in which the phase shift film 30 has a fine columnar structure is shown, and the phase shift film pattern 30a obtained by forming the phase shift film 30 by wet etching as the spatial frequency is at a position farther from the origin This is preferable because the line edge roughness of .

It is preferable that the press-in hardness of this phase shift film 30 is 18 GPa or more and 23 GPa or less. This indentation hardness is a hardness measured using the principle of the nanoindentation method established in ISO14577.

By setting the indentation hardness of this phase shift film 30 to 18 GPa or more and 23 GPa or less, at the time of wet etching using a wet etchant, since the wet etchant becomes easy to permeate in the film thickness direction of the phase shift film 30, the wet etching rate increases , the wet etching time can be shortened. In addition, the phase shift film pattern 30a having suitable characteristics as the phase shift film 30 and having a good cross-sectional shape can be formed, and the surface roughness of the transparent substrate 20 can be suppressed. , the cleaning resistance of the phase shift film 30 can be improved.

It is preferable that the atomic ratio of the transition metal contained in the phase shift film 30 and silicon is transition metal:silicon=1:3 or more and 1:15 or less. If it is this range, the effect of suppressing the wet-etching rate fall at the time of pattern formation of the phase shift film 30 by a columnar structure can be enlarged. Moreover, the cleaning resistance of the phase shift film 30 can be improved, and it becomes easy to raise transmittance|permeability. Moreover, if it is this range, the effect of suppressing the wet-etching rate fall at the time of pattern formation of the phase shift film 30 by making indentation hardness into 18 GPa or more and 23 GPa or less can be enlarged. At the time of improving the cleaning resistance of the phase shift film 30, the atomic ratio of transition metal and silicon contained in the phase shift film 30 is transition metal:silicon=1:4 or more and 1:15 or less, more preferably. , transition metal:silicon = 1:5 or more and 1:15 or less are preferable.

The transmittance of the phase shift film 30 to exposure light satisfies a value required for the phase shift film 30 . The transmittance of the phase shift film 30 is preferably 1% or more and 80% or less, more preferably 15% or more with respect to light of a predetermined wavelength included in exposure light (hereinafter referred to as representative wavelength). It is 65% or less, More preferably, it is 20% or more and 60% or less. That is, when the exposure light is composite light containing light in a wavelength range of 313 nm or more and 436 nm or less, the phase shift film 30 has the above-described transmittance with respect to light of a representative wavelength included in the wavelength range. For example, when exposure light is composite light containing i-line, h-line, and g-line, the phase shift film 30 has the above-mentioned transmittance|permeability about any of i-line, h-line, and g-line.

The transmittance can be measured using a phase shift amount measuring device or the like.

The phase difference of the phase shift film 30 with respect to exposure light satisfies the value required as the phase shift film 30 . The phase difference of the phase shift film 30 is preferably 160° or more and 200° or less, more preferably 170° or more and 190° or less with respect to light of a representative wavelength included in exposure light. Due to 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. For this reason, a phase difference of 160° or more and 200° or less occurs between light of a representative wavelength transmitted through the phase shift film 30 and light of a representative wavelength transmitted only through the transparent substrate 20 . That is, when the exposure light is composite light containing light in a wavelength range of 313 nm or more and 436 nm or less, the phase shift film 30 has the above-described phase difference with respect to light of a representative wavelength included in the wavelength range. For example, when exposure light is composite light containing i-line, h-line, and g-line, the phase shift film 30 has the above-mentioned phase difference with respect to any of i-line, h-line, and g-line.

The phase difference can be measured using a phase shift amount measuring device or the like.

The back surface reflectance of the phase shift film 30 is 15% or less in the wavelength range of 365 nm - 436 nm, and it is preferable in it being 10% or less. In addition, the reflectance of the back surface of the phase shift film 30 is preferably 20% or less for light in a wavelength range of 313 nm to 436 nm, more preferably 17% or less, when j-line is included in exposure light. More preferably, it is desirable that it is 15% or less. In addition, the back surface reflectance of the phase shift film 30 is 0.2% or more in a wavelength range of 365 nm to 436 nm, and is preferably 0.2% or more with respect to light in a wavelength range of 313 nm to 436 nm.

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

This phase shift film 30 may be composed of a plurality of layers or may be composed of a single layer. The phase shift film 30 composed of a single layer is preferable in that an interface is hardly formed in the phase shift film 30 and the cross-sectional shape is easily controlled. On the other hand, the phase shift film 30 composed of a plurality of layers is preferable in terms of ease of film formation and the like.

The etching mask film 40 is disposed above the phase shift film 30 and is made of a material having etching resistance to an etchant used to etch the phase shift film 30 (different in etching selectivity from that of the phase shift film 30). made up of Further, the etching mask film 40 may have a function of blocking transmission of exposure light, and the film surface reflectance of the phase shift film 30 to light incident from the phase shift film 30 side is 350 nm to 350 nm. It may have a function of reducing the film surface reflectance to 15% or less in the wavelength range of 436 nm. The etching mask film 40 is made of a chromium-based material containing chromium (Cr). As the chromium-based material, more specifically, chromium (Cr) or a material containing chromium (Cr) and at least one of oxygen (O), nitrogen (N), and carbon (C) is exemplified. Alternatively, a material containing at least one of chromium (Cr), oxygen (O), nitrogen (N), and carbon (C), and further containing fluorine (F) is exemplified. For example, materials constituting the etching mask film 40 include Cr, CrO, CrN, CrF, CrCO, CrCN, CrON, CrCON, and CrCONF.

The etching mask film 40 can be formed by sputtering.

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

Optical density can be measured using a spectrophotometer or OD meter.

The etching mask film 40 may be composed of a single film having a uniform composition or a plurality of films having different compositions depending on the function, or a single film whose composition continuously changes in the thickness direction. may be the case.

In addition, the phase shift mask blank 10 shown in FIG. 1 has the etching mask film 40 on the phase shift film 30, but has the etching mask film 40 on the phase shift film 30. The present invention can also be applied to a phase shift mask blank having a resist film on the etching mask film 40.

Next, the manufacturing method of the phase shift mask blank 10 of this Embodiment 1 and 2 is demonstrated. The phase shift mask blank 10 shown in FIG. 1 is manufactured by performing the following phase shift film formation process and etching mask film formation process. The phase shift mask blank 10 shown in FIG. 2 is manufactured by the phase shift film formation process.

Hereinafter, each process is demonstrated in detail.

1. Phase shift film formation process

First, a transparent substrate 20 is prepared. If the transparent substrate 20 is transparent to exposure light, it is composed of any glass material such as synthetic quartz glass, quartz glass, aluminosilicate glass, soda lime glass, or low thermal expansion glass (such as SiO ₂ -TiO ₂ glass). It could be anything.

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

The film formation of the phase shift film 30 is carried out using a transition metal silicide target containing silicon and a transition metal as main components of the material constituting the phase shift film 30, or a transition metal containing silicon, oxygen and/or nitrogen. A sputtering gas atmosphere made of an inert gas containing at least one selected from the group consisting of helium gas, neon gas, argon gas, krypton gas, and xenon gas, for example, using a transition metal silicide target as a sputter target; It is performed in a sputtering gas atmosphere composed of a mixed gas of an inert gas and an active gas selected from the group consisting of oxygen gas, nitrogen gas, carbon dioxide gas, nitrogen monoxide gas, and nitrogen dioxide gas and containing at least oxygen and nitrogen. And the phase shift film 30 is formed by the gas pressure in the film-forming chamber at the time of sputtering being 0.7 Pa or more and 3.0 Pa or less. Preferably, the phase shift film 30 is formed at a gas pressure of 0.8 Pa or more and 3.0 Pa in the film formation chamber at the time of sputtering. 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, a high etching rate can be achieved while being able to suppress side etching at the time of pattern formation described later. Here, the atomic ratio of the transition metal to silicon of the transition metal silicide target is transition metal:silicon = 1:3 or more and 1:15 or less, the effect of suppressing the decrease in the wet etching rate by the columnar structure is large, and the phase shift film (30) is preferable in that the cleaning resistance can be improved and the transmittance can be easily increased.

The composition and thickness of the phase shift film 30 are adjusted such that the phase shift film 30 has the above phase difference and transmittance. The composition of the phase shift film 30 can be controlled by the content ratio of elements constituting the sputtering target (for example, the ratio between the content ratio of transition metal and the content ratio of silicon), the composition and flow rate of sputtering gas, and the like. The thickness of the phase shift film 30 can be controlled by sputtering power, sputtering time, and the like. In addition, it is preferable to form the phase shift film 30 using an in-line type sputtering device. When the sputtering device is an inline type sputtering device, the thickness of the phase shift film 30 can be controlled also by the transport speed of the substrate. Thus, control is performed so that the content rate of the light element component containing oxygen and nitrogen of the phase shift film 30 may be 40 atomic % or more and 70 atomic % or less.

When the phase shift film 30 consists of a single film, the film formation process described above is performed only once by appropriately adjusting the composition and flow rate of the sputtering gas. When the phase shift film 30 consists of a some film|membrane from which a composition differs, the above-mentioned film-forming process is performed several times by adjusting the composition and flow volume of sputtering gas appropriately. You may form the phase shift film 30 into a film using the target from which the content rate of the element which comprises a sputtering target differs. When the film formation process is performed a plurality of times, the sputtering power applied to the sputtering target may be changed for each film formation process.

2. Surface treatment process

The phase shift film 30 contains 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. In order to suppress permeation of the surface of the phase shift film 30 by the etchant due to the presence of an oxide of the transition metal when it is made of a transition metal silicide material, the state of oxidation of the surface of the phase shift film 30 is adjusted. You may make it perform a surface treatment process. In addition, when the phase shift film 30 is made of a transition metal silicide nitride containing a transition metal, silicon, and nitrogen, the content of the oxide of the transition metal is higher than that of the above-mentioned transition metal silicide material containing oxygen. small. Therefore, when the material of the phase shift film 30 is a transition metal silicide nitride, you may or may not perform the said surface treatment process.

As the surface treatment step for adjusting the surface oxidation state of the phase shift film 30, a method of surface treatment with an acidic aqueous solution, a method of surface treatment with an alkaline aqueous solution, a method of surface treatment by dry treatment such as ashing, etc. are mentioned. can

In this way, the phase shift mask blank 10 of Embodiment 2 is obtained. In manufacture of the phase shift mask blank 10 of Embodiment 1, the following etching mask film formation process is further performed.

3. Etching Mask Film Formation Process

After the phase shift film formation step, if necessary, surface treatment for adjusting the state of surface oxidation of the surface of the phase shift film 30 is performed, and thereafter, on the phase shift film 30 by a sputtering method. An etching mask film 40 is formed thereon. The etching mask film 40 is preferably formed using an in-line sputtering device. When the sputtering device is an inline type sputtering device, the thickness of the etching mask film 40 can be controlled also by the transfer speed of the transparent substrate 20 .

The film formation of the etching mask film 40 is performed using a sputter target containing chromium or a chromium compound (chromium oxide, chromium nitride, chromium carbide, chromium oxynitride, chromium oxynitride carbide, etc.), for example, helium gas, neon gas, argon gas, sputter gas atmosphere made of an inert gas containing at least one selected from the group consisting of krypton gas and xenon gas, or selected from the group consisting of helium gas, neon gas, argon gas, krypton gas and xenon gas Mixing of an inert gas containing at least one gas with an active gas containing at least one selected from the group consisting of oxygen gas, nitrogen gas, nitrogen monoxide gas, nitrogen dioxide gas, carbon dioxide gas, hydrocarbon gas, and fluorine gas. It is performed in a sputtering gas atmosphere composed of gas. As hydrocarbon-type gas, methane gas, butane gas, propane gas, styrene gas etc. are mentioned, for example. And the etching mask film|membrane 40 can be made into a columnar structure similarly to the phase shift film 30 by adjusting the gas pressure in the film-forming chamber at the time of sputtering. Thereby, while side etching at the time of pattern formation mentioned later can be suppressed, a high etching rate can be achieved.

When the etching mask film 40 is composed of a single film having a uniform composition, the film formation process described above is performed only once without changing the composition and flow rate of the sputter gas. When the etching mask film 40 is composed of a plurality of films having different compositions, the above-described film formation process is performed a plurality of times by changing the composition and flow rate of the sputter gas for each film formation process. When the etching mask film 40 is composed of a single film whose composition continuously changes in the thickness direction, the above-described film formation process is performed only once while changing the composition and flow rate of the sputter gas along with the elapsed time of the film formation process.

In this way, the phase shift mask blank 10 of Embodiment 1 is obtained.

In addition, since the phase shift mask blank 10 shown in FIG. 1 is equipped with the etching mask film 40 on the phase shift film 30, when manufacturing the phase shift mask blank 10, an etching mask film A formation process is performed. In addition, when manufacturing a phase shift mask blank having an etching mask film 40 on the phase shift film 30 and a resist film on the etching mask film 40, after the etching mask film formation step, the etching mask A resist film is formed on the film 40 . In addition, in the phase shift mask blank 10 shown in FIG. 2, when manufacturing the phase shift mask blank provided with the resist film on the phase shift film 30, a resist film is formed after a phase shift film formation process.

In the phase shift mask blank 10 of this Embodiment 1, the etching mask film 40 is formed on the phase shift film 30, and at least the phase shift film 30 has a columnar structure. In the phase shift mask blank 10 of Embodiment 2, a phase shift film 30 is formed, and this phase shift film 30 has a columnar structure.

The phase shift mask blank 10 of Embodiments 1 and 2 has a good cross-sectional shape because etching in the film thickness direction is promoted while side etching is suppressed when the phase shift film 30 is patterned by wet etching. And, a phase shift film pattern having a desired transmittance (eg, high transmittance) can be formed in a short etching time. Therefore, a phase shift mask blank capable of producing a phase shift mask capable of transferring a high-precision phase shift film pattern with high accuracy without a decrease in the transmittance of the transparent substrate due to damage to the substrate by the wet etching solution is obtained. lose

Moreover, when forming the phase shift film 30 on the transparent substrate 20, you may make it form in the gas pressure in the film formation chamber at the time of sputtering being 0.7 Pa or more and 2.4 Pa or less. By setting the range of gas pressure in this way, it is possible to form the phase shift film 30 whose indentation hardness derived by the nanoindentation method is 18 GPa or more and 23 GPa or less. While being able to suppress the side etching at the time of pattern formation mentioned later by making the indentation hardness of the phase shift film 30 into 18 GPa or more and 23 GPa or less, a high etching rate can be achieved, and of the transparent substrate 20 Surface roughness can be suppressed. Here, the atomic ratio of the transition metal to silicon of the transition metal silicide target is transition metal:silicon=1:3 or more and 1:15 or less, as described above, to reduce the wet etching rate and indentation hardness to 18 GPa or more and 23 GPa or less It is preferable from the viewpoint that the suppressing effect is large, the cleaning resistance of the phase shift film 30 can be improved, and it is easy to increase the transmittance.

Embodiment 3. 4.

In Embodiment 3 and 4, the manufacturing method of a phase shift mask is demonstrated.

3 is a schematic diagram showing a manufacturing method of a phase shift mask according to Embodiment 3; 4 is a schematic diagram showing a manufacturing method of a phase shift mask according to Embodiment 4;

The manufacturing method of the phase shift mask shown in FIG. 3 is a method of manufacturing a phase shift mask using the phase shift mask blank 10 shown in FIG. 1, and the etching mask film 40 of the following phase shift mask blank 10 ), forming a resist film pattern 50 by performing a process of forming a resist film on the resist film and drawing and developing a desired pattern on the resist film (first resist film pattern forming process), and the resist film pattern 50 A step of wet etching the etching mask film 40 as a mask and forming an etching mask film pattern 40a on the phase shift film 30 (first etching mask film pattern forming process), and the etching mask film pattern (40a) is used as a mask, the phase shift film 30 is wet-etched, and the process of forming the phase shift film pattern 30a on the transparent substrate 20 (phase shift film pattern formation process) is included. And, a second resist film pattern forming process and a second etching mask film pattern forming process are further included.

The manufacturing method of the phase shift mask shown in FIG. 4 is a method of manufacturing a phase shift mask using the phase shift mask blank 10 shown in FIG. 2, and forming a resist film on the following phase shift mask blank 10 Step, by drawing and developing a desired pattern on the resist film, forming a resist film pattern 50 (first resist film pattern forming step), using the resist film pattern 50 as a mask, forming a phase shift film ( 30) is wet-etched, and the process of forming the phase shift film pattern 30a on the transparent substrate 20 (phase shift film pattern formation process) is included.

Hereinafter, each process of the manufacturing process of the phase shift mask concerning Embodiment 3 and 4 is demonstrated in detail.

Phase shift mask manufacturing process according to Embodiment 3

1. First resist film pattern formation process

In the first resist film pattern formation process, 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 to be used is not particularly limited. For example, what is necessary is just to be sensitive to the laser beam which has a certain wavelength selected from the wavelength range of 350 nm - 436 nm mentioned later. In addition, the resist film may be either positive type or negative type.

After that, a desired pattern is drawn on the resist film using a laser beam having a certain wavelength selected from a wavelength range of 350 nm to 436 nm. The pattern drawn on the resist film is a pattern formed on the phase shift film 30 . As a pattern to be drawn on the resist film, a line and space pattern and a hole pattern are exemplified.

Thereafter, the resist film is developed with a predetermined developer, and a first resist film pattern 50 is formed on the etching mask film 40 as shown in FIG. 3(a).

2. First etching mask film pattern formation process

In the first etching mask film pattern forming process, first, the etching mask film 40 is etched using the first resist film pattern 50 as a mask to form a first etching mask film pattern 40a. The etching mask film 40 is formed of a chromium-based material containing chromium (Cr). When the etching mask film 40 has a columnar structure, the etching rate is high and side etching can be suppressed, which is preferable. An 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 etchant containing ceric ammonium nitrate and perchloric acid is exemplified.

After that, the first resist film pattern 50 is stripped using a resist stripping solution or by ashing, as shown in FIG. 3(b). Depending on the case, you may perform the next phase shift film pattern formation process, without peeling the 1st resist film pattern 50.

3. Phase shift film pattern formation process

In the first phase shift film pattern forming step, the phase shift film 30 is wet-etched using the first etching mask film pattern 40a as a mask, and as shown in FIG. 3(c), the phase shift film pattern ( 30a). As the phase shift film pattern 30a, a line-and-space pattern or a hole pattern can be used. The etchant 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 etchant containing ammonium fluoride, phosphoric acid, and hydrogen peroxide, and an etchant containing ammonium hydrogen fluoride and hydrogen peroxide are exemplified.

In order to improve the cross-sectional shape of the phase shift film pattern 30a, wet etching is performed for a longer time (over-etching time) than the time until the transparent substrate 20 is exposed in the phase shift film pattern 30a. etching time) is preferred. As the over-etching time, considering the effect on the transparent substrate 20 and the like, it is preferable to set the time to be within the time obtained by adding 20% of the just-etching time to the just-etching time, and 10% of the just-etching time It is more preferable to do it within the added time.

4. Second resist film pattern formation process

In the second resist film pattern forming process, first, a resist film covering the first etching mask film pattern 40a is formed. The resist film material to be used is not particularly limited. For example, what is necessary is just to be sensitive to the laser beam which has a certain wavelength selected from the wavelength range of 350 nm - 436 nm mentioned later. In addition, the resist film may be either positive type or negative type.

After that, a desired pattern is drawn on the resist film using a laser beam having a certain wavelength selected from a wavelength range of 350 nm to 436 nm. The pattern to be drawn on the resist film is a light-shielding band pattern for shielding the outer periphery of the region where the pattern is formed in the phase shift film 30, a light-shielding band pattern for shielding the central portion of the phase shift film pattern, and the like. In addition, the pattern drawn on the resist film may be a pattern without a light-shielding band pattern that blocks the central portion of the phase shift film pattern 30a depending on the transmittance of the phase shift film 30 to exposure light.

Thereafter, the resist film is developed with a predetermined developer, and a second resist film pattern 60 is formed on the first etching mask film pattern 40a as shown in FIG. 3(d).

5. Second etching mask film pattern formation process

In the second etching mask film pattern forming process, the first etching mask film pattern 40a is etched using the second resist film pattern 60 as a mask, and as shown in FIG. 3(e), the second etching mask A film pattern 40b is formed. The first etching mask film pattern 40a is formed of a chromium-based material containing chromium (Cr). An etchant 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 etchant containing ceric ammonium nitrate and perchloric acid is exemplified.

After that, the second resist film pattern 60 is stripped using a resist stripping solution or by ashing.

In this way, the phase shift mask 100 is obtained.

Incidentally, in the above description, the case where the etching mask film 40 has a function of blocking transmission of exposure light has been described, but the etching mask film 40 is simply a hard mask when the phase shift film 30 is etched. In the case of having only the function of, in the above description, the second resist film pattern forming process and the second etching mask film pattern forming process are not performed, and after the phase shift film pattern forming process, the first etching mask film pattern is formed. It is peeled off and the phase shift mask 100 is produced.

According to the manufacturing method of the phase shift mask of this Embodiment 3, since the phase shift mask blank of Embodiment 1 is used, etching time can be shortened and a phase shift film pattern with a favorable cross-sectional shape can be formed. Therefore, it is possible to manufacture a phase shift mask capable of transferring a high-precision phase shift film pattern with high precision. The phase shift mask manufactured in this way can respond to miniaturization of line-and-space patterns and contact holes.

Phase shift mask manufacturing process according to Embodiment 4

1. Resist film pattern formation process

In the resist film pattern formation step, first, a resist film is formed on the phase shift film 30 of the phase shift mask blank 10 of the second embodiment. The resist film material used is the same as that described in Embodiment 3. In addition, before forming a resist film as needed, in order to make the phase shift film 30 and adhesiveness favorable, you may make it surface-modify the phase shift film 30. As in the above, after the resist film is formed, a desired pattern is drawn on the resist film using laser light having a certain wavelength selected from the wavelength range of 350 nm to 436 nm. After that, the resist film is developed with a predetermined developer, and a resist film pattern 50 is formed on the phase shift film 30 as shown in FIG. 4(a).

2. Phase shift film pattern formation process

In the phase shift film pattern formation step, the phase shift film 30 is etched using the resist film pattern as a mask, and the phase shift film pattern 30a is formed as shown in Fig. 4(b). Etching liquid and over-etching time which etch the phase shift film pattern 30a and the phase shift film 30 are the same as those demonstrated in Embodiment 3.

After that, the resist film pattern 50 is stripped using a resist stripping solution or by ashing (FIG. 4(c)).

In this way, the phase shift mask 100 is obtained.

According to the manufacturing method of the phase shift mask of Embodiment 4, since the phase shift mask blank of Embodiment 2 is used, there is no decrease in the transmittance of the transparent substrate due to damage to the substrate by the wet etchant, and the etching time can be shortened, and a phase shift film pattern with a good cross-sectional shape can be formed. Therefore, it is possible to manufacture a phase shift mask capable of transferring a high-precision phase shift film pattern with high precision. The phase shift mask manufactured in this way can respond to miniaturization of line-and-space patterns and contact holes. In addition, in the case of manufacturing a phase shift mask using a phase shift mask blank having a phase shift film 30 having an indentation hardness of 18 GPa or more and 23 GPa or less derived by the nanoindentation method, in addition to the above-mentioned effects, transparency While the surface roughness of the substrate 20 can be suppressed, the cleaning resistance of the phase shift film 30 can be improved.

Embodiment 5.

In Embodiment 5, a manufacturing method of a display device is described. The display device uses the phase shift mask 100 manufactured using the phase shift mask blank 10 described above, or the phase shift mask 100 manufactured by the manufacturing method of the phase shift mask 100 described above It is manufactured by performing a process of using (mask loading process) and a process of exposing and transferring a transfer pattern to a resist film on a display device (exposure process).

Hereinafter, each process is demonstrated in detail.

1. Loading process

In the loading process, the phase shift mask manufactured in Embodiment 3 is loaded on the mask stage of the exposure apparatus. Here, the phase shift mask is arranged so as to face the resist film formed on the display device substrate through the projection optical system of the exposure device.

2. Pattern transfer process

In the pattern transfer step, the phase shift mask 100 is irradiated with exposure light, and the phase shift film pattern is transferred to the resist film formed on the display device substrate. The exposure light is composite light containing light of a plurality of wavelengths selected from the wavelength range of 365 nm to 436 nm, or monochromatic light selected by cutting a certain wavelength range from the wavelength range of 365 nm to 436 nm with a filter or the like. For example, the exposure light is composite light including i-line, h-line, and g-line, or monochromatic light of i-line. If the composite light is used as the exposure light, the intensity of the exposure light can be increased and the throughput can be increased, so the manufacturing cost of the display device can be reduced.

According to the manufacturing method of the display device of this Embodiment 3, it is possible to manufacture a high-precision display device having a high-resolution, fine line-and-space pattern or contact holes.

Further, in the above embodiment, a phase shift mask blank having a phase shift mask film or a phase shift mask having a phase shift mask film pattern is used as a photomask blank having a thin film for pattern formation or a photomask having a transfer pattern. Although the case has been described, it is not limited thereto. For example, the present invention can be applied also to a binary mask blank having a light-shielding film as a thin film for pattern formation or a binary mask having a light-shielding film pattern.

[Example]

Example 1.

A. Phase Shift Mask Blanks and Manufacturing Methods Thereof

In order to manufacture the phase shift mask blank of Example 1, first, as the transparent substrate 20, a 1214 size (1220 mm x 1400 mm) synthetic quartz glass substrate was prepared.

Thereafter, the synthetic quartz glass substrate was mounted on a tray (not shown) with the main surface facing downward, and was carried into the chamber of the inline type sputtering device.

In order to form the phase shift film 30 on the main surface of the transparent substrate 20, argon (Ar) gas and nitrogen (N ₂ ) gas are first set in a state where the sputtering gas pressure in the first chamber is 1.6 Pa. and an inert gas (Ar: 18 sccm, N ₂ : 13 sccm, He: 50 sccm) composed of helium (He) gas was introduced. Then, a sputtering power of 7.6 kW was applied to a first sputtering target containing molybdenum and silicon (molybdenum:silicon = 1:9), and reactive sputtering resulted in molybdenum and silicon on the main surface of the transparent substrate 20. A nitride of molybdenum silicide containing nitrogen was deposited. And the phase shift film 30 of film thickness 150nm was formed into a film.

Next, the transparent substrate 20 provided with the phase shift film 30 is carried into the second chamber, and a mixed gas of argon (Ar) gas and nitrogen (N ₂ ) gas (Ar: 65 sccm, N ₂ : 15 sccm) was introduced. Then, a sputtering power of 1.5 kW was applied to the second sputter target made of chromium, and chromium nitride (CrN) containing chromium and nitrogen was formed on the phase shift film 30 by reactive sputtering (film thickness 15 nm). Next, with the inside of the third chamber at a predetermined degree of vacuum, a mixed gas (30 sccm) of argon (Ar) gas and methane (CH ₄ : 4.9%) gas is introduced, and the third sputter target made of chromium is 8.5 A sputtering power of kW was applied, and chromium carbide (CrC) containing chromium and carbon was formed on CrN by reactive sputtering (film thickness: 60 nm). Finally, in a state where the inside of the fourth chamber has a predetermined degree of vacuum, a mixed gas of argon (Ar) gas and methane (CH ₄ : 5.5%) gas, nitrogen (N ₂ ) gas, and oxygen (O ₂ ) gas are mixed A gas (Ar+CH ₄ : 30 sccm, N ₂ : 8 sccm, O ₂ : 3 sccm) was introduced, a sputtering power of 2.0 kW was applied to a fourth sputter target made of chromium, and chromium and carbon were applied on CrC by reactive sputtering. and chromium carbonized oxynitride (CrCON) containing oxygen and nitrogen (film thickness: 30 nm). As described above, the etching mask film 40 having a laminated structure of a CrN layer, a CrC layer, and a CrCON layer was formed on the phase shift film 30 .

In this way, the phase shift mask blank 10 in which the phase shift film 30 and the etching mask film 40 were formed on the transparent substrate 20 was obtained.

About the surface of the phase shift film 30 (phase shift film 30) of the obtained phase shift mask blank 10, the transmittance|permeability and the phase difference were measured with MPM-100 by Lasertec Corporation. In the measurement of the transmittance and phase difference of the phase shift film 30, a substrate (dummy substrate) provided with a phase shift film in which the phase shift film 30 is formed on the main surface of a synthetic quartz glass substrate prepared by setting it on the same tray. was used. The transmittance and phase difference of the phase shift film 30 were measured by taking out the substrate (dummy substrate) with the phase shift film from the chamber before forming the etching mask film 40 . As a result, the transmittance was 27% (wavelength: 405 nm) and the phase difference was 178° (wavelength: 405 nm).

Moreover, about the obtained phase shift mask blank 10, the compositional analysis of the depth direction by X-ray photoelectron spectroscopy (XPS) was performed.

In the result of compositional analysis of the phase shift mask blank 10 in the depth direction by XPS, the phase shift film 30 has a composition gradient region at the interface between the transparent substrate 20 and the phase shift film 30, and the phase Excluding the composition gradient region at the interface between the shift film 30 and the etching mask film 40, the content of each constituent element is almost constant in the depth direction, with 8 atomic% of Mo, 40 atomic% of Si, and N This 48 atom% and O were 4 atom%. Moreover, the atomic ratio of molybdenum and silicon was 1:5, and was within the range of 1:3 or more and 1:15 or less. In addition, the total content rate of oxygen and nitrogen as light elements was 52 atomic%, and was within the range of 50 atomic% or more and 65 atomic% or less. In addition, it is considered that the reason why oxygen is contained in the phase shift film 30 is that the sputtering gas pressure is as high as 0.8 Pa or more, and a small amount of oxygen is present in the chamber at the time of film formation.

Moreover, when the indentation hardness of the obtained phase shift film 30 was measured (the measuring method is mentioned later), the indentation hardness satisfies 18 GPa or more and 23 GPa or less.

Next, as a result of cross-sectional SEM (scanning electron microscope) observation at a magnification of 80000 times at a position in the center of the transfer pattern formation region of the obtained phase shift mask blank 10, the phase shift film 30 has a columnar structure. It has been confirmed that you have That is, it was confirmed that the particles of the molybdenum silicide compound constituting the phase shift film 30 have a columnar particle structure extending in the film thickness direction of the phase shift film 30 . And, as for the columnar grain structure of the phase shift film 30, it was confirmed that the columnar grains in the film thickness direction were formed irregularly, and the length of the columnar grains in the film thickness direction was not even. It was also confirmed that small portions of the phase shift film 30 were continuously formed in the film thickness direction. In addition, with respect to the image obtained by this cross-sectional SEM observation, about the area|region containing the center part of the thickness direction of the phase shift film 30, it extracted as image data of 64 vertical pixels x 256 horizontal pixels (FIG. 5(a) )). Further, Fourier transform was performed on the image data shown in Fig. 5 (Fig. 5(b)). In the spatial frequency spectrum distribution obtained by Fourier transform, the signal intensity (maximum signal intensity) at the origin of the spatial frequency is 3136000, and apart from the maximum signal intensity, a spatial frequency spectrum having a signal intensity of 66150 exists. Confirmed. This is 66150/3136000 = 0.021 (i.e., 2.1%) with respect to the maximum signal intensity corresponding to the origin of the spatial frequency, and the phase shift film 30 was a columnar structure having a signal intensity of 1.0% or more.

In addition, for the image of the Fourier transform of FIG. 5(b), the origin of the spatial frequency, that is, the center of the image of FIG. 5(b) is set as the origin (0), and the maximum When the spatial frequency is 1 (100%), a signal having a signal strength of 2.1% of the maximum signal strength corresponding to the origin of the spatial frequency has a columnar structure having a signal at a position 0.055, or 5.5%, away from the origin. It was a phase shift film 30 with The same applies to images of Fourier transforms in subsequent examples and comparative examples.

Further, in the vicinity of the center of the film thickness of this phase shift film 30, a plate-shaped sample of 100 nm in a direction perpendicular to the film thickness direction (in-plane direction of the substrate) was taken, and dark-field planar STEM observation was performed. The results of dark-field planar STEM (scanning transmission electron microscope) observation are shown in FIG. 6 . As shown in Fig. 6, gray-white and gray-black uneven patterns, which are considered to be between the columnar particle portion (grey-white portion) and between the particles (gray-black portion), were observed. Quantitative analysis of the elements (Mo, Si, N, and O) constituting the phase shift film 30 was performed by EDX analysis (energy dispersive X-ray analysis) for these gray-white and gray-black locations (not shown). not). As a result, in the gray-black part and the gray-white part, the detected amount (count number) of Si is higher than that of Mo, and the detected amount (count number) of the constituent elements of the phase shift film 30 in the gray-black part is It was confirmed that it was lower than the detected amount (number of counts) of the constituent elements of the phase shift film 30 in . In particular, the detected amount (counts) of Si in the grayish-black part is 600 (Counts), the detected amount (counts) of Si in the grayish-white part is 400 (Counts), and the detected amount compared to other elements. The difference in (number of counts) was large. From this result, it was confirmed that the phase shift film 30 had a relatively high-density particle portion (grey-white portion) and a relatively low-density small portion (gray-black portion). This particle portion corresponds to the columnar particles shown in FIGS. 5 and 7 . Moreover, the film density of the whole phase shift film 30 is lower than the film density of the conventional phase shift film.

B. Phase shift mask and its manufacturing method

In order to manufacture the phase shift mask 100 using the phase shift mask blank 10 manufactured as described above, first, a resist coating device is used on the etching mask film 40 of the phase shift mask blank 10 Then, a photoresist film was applied.

Thereafter, a photoresist film having a film thickness of 520 nm was formed through a heating/cooling process.

Thereafter, the photoresist film was drawn using a laser drawing device, and a resist film pattern of a hole pattern having a hole diameter of 1.5 μm was formed on the etching mask film through a developing and rinsing process.

Thereafter, using the resist film pattern as a mask, the etching mask film was wet-etched with a chromium etchant containing ceric ammonium nitrate and perchloric acid to form a first etching mask film pattern 40a.

Thereafter, using the first etching mask film pattern 40a as a mask, the phase shift film 30 is wet-etched with a molybdenum silicide etchant obtained by diluting a mixed solution of ammonium hydrogen fluoride and hydrogen peroxide with pure water, thereby forming a phase shift film pattern. (30a) was formed. This wet etching was performed with an over-etching time of 110% in order to verticalize the cross-sectional shape and to form a fine pattern required. Compared with the just etching time in the comparative example mentioned later, the just etching time in Example 1 became 0.15 times, and it was able to shorten etching time significantly.

After that, the resist film pattern was peeled off.

Then, using a resist coating device, a photoresist film was applied so as to cover the first etching mask film pattern 40a.

Thereafter, a photoresist film having a film thickness of 520 nm was formed through a heating/cooling process.

Thereafter, a photoresist film is drawn using a laser drawing device, and a second resist film pattern 60 for forming a light-shielding band is formed on the first etching mask film pattern 40a through a developing and rinsing process. did

Thereafter, using the second resist film pattern 60 as a mask, the first etching mask film pattern 40a formed in the transfer pattern forming region was wet etched with a chromium etching solution containing ceric ammonium nitrate and perchloric acid. .

After that, the second resist film pattern 60 was peeled off.

In this way, on the transparent substrate 20, the phase shift film pattern 30a having a hole diameter of 1.5 μm in the transfer pattern formation region, the phase shift film pattern 30a and the etching mask film pattern 40b. A phase shift mask 100 with a light-shielding band formed of was obtained.

A cross section of the obtained phase shift mask was observed with a scanning electron microscope. The cross section of the phase shift film pattern is constituted by the upper surface, lower surface and side surface of the phase shift film pattern. The angle of the cross section of this phase shift film pattern refers to the angle formed by the part where the upper surface and side surface of a phase shift film pattern contact (upper edge) and the part where the side surface and lower surface contact each other (lower edge). The angle of the cross section of the phase shift film pattern 30a of the obtained phase shift mask was 74 degrees, and had a cross-sectional shape close to vertical. The phase shift film pattern 30a formed on the phase shift mask of Example 1 had a cross-sectional shape capable of sufficiently exhibiting the phase shift effect. It is considered that the reason why the phase shift film pattern 30a has a favorable cross-sectional shape by making the phase shift film 30 a columnar structure is based on the following mechanism. From the observation result of the cross-sectional SEM photograph in FIG. 7 , the phase shift film 30 has a columnar particle structure (columnar structure), and columnar particles extending in the film thickness direction are irregularly formed. Further, from the observation results of the dark field plane STEM photograph of FIG. 6 and the observation result of the cross-sectional SEM photograph of FIG. 7 , the phase shift film 30 has a relatively high-density particle portion of each columnar phase and a relatively low-density It is formed from small parts. From these facts, when patterning the phase shift film 30 by wet etching, the etchant permeates a small portion in the phase shift film 30, so that the etching proceeds easily in the film thickness direction, while the film thickness Since the columnar grains are irregularly formed in the direction perpendicular to the direction (the direction within the substrate surface) and small portions in this direction are intermittently formed, etching in this direction is difficult to proceed and side etching is suppressed. , it is considered that the favorable cross-sectional shape of the phase shift film pattern 30a close to vertical was obtained. In addition, permeation was not seen in either of the interface with the etching mask film pattern and the interface with the substrate in the phase shift film pattern. Therefore, in exposure light containing light in a wavelength range of 300 nm or more and 500 nm or less, more specifically, exposure light of composite light including i-line, h-line, and g-line, a phase having an excellent phase shift effect A shift mask was obtained.

For this reason, when the phase shift mask of Example 1 is set on the mask stage of the exposure apparatus and exposed and transferred to the resist film on the display apparatus, it can be said that a fine pattern of less than 2.0 µm can be transferred with high precision.

In addition, in the cross-sectional SEM photograph of FIG. 7, in the phase shift mask manufacturing process of Example 1, the phase shift film 30 was wetted with a molybdenum silicide etchant using the first etching mask film pattern 40a as a mask. It is a cross-sectional SEM photograph after carrying out etching (over-etching of 110%), forming the phase shift film pattern 30a, and peeling off the resist film pattern. As shown in Fig. 7, the phase shift film pattern 30a maintains the columnar structure of the phase shift film 30, and the exposed surface of the transparent substrate 20 after removing the phase shift film 30 is It was smooth, and the decrease in transmittance due to surface roughness of the transparent substrate 20 was in a state where it could be ignored.

Example 2.

A. Phase Shift Mask Blanks and Manufacturing Methods Thereof

In order to manufacture the phase shift mask blank of Example 2, similarly to Example 1, it was set as the transparent substrate, and the synthetic quartz glass substrate of 1214 size (1220 mm x 1400 mm) was prepared.

In the same manner as in Example 1, a synthetic quartz glass substrate was introduced into the chamber of an inline sputtering device. As the 1st sputter target, the 2nd sputter target, the 3rd sputter target, and the 4th sputter target, the same sputter target material as Example 1 was used. Then, in a state where the sputtering gas pressure in the first chamber is 1.6 Pa, an inert gas composed of argon (Ar) gas, helium (He) gas, and nitrogen (N ₂ ) gas, and nitrogen monoxide gas (NO) as a reactive gas ) was introduced into a mixed gas (Ar: 18 sccm, N ₂ : 15 sccm, He: 50 sccm, NO: 4 sccm). Then, a sputtering power of 7.6 kW was applied to a first sputtering target containing molybdenum and silicon (molybdenum:silicon = 1:9), and reactive sputtering resulted in molybdenum and silicon on the main surface of the transparent substrate 20. An oxynitride of molybdenum silicide containing oxygen and nitrogen was deposited. And the phase shift film 30 of film thickness 140nm was formed into a film.

And after forming the phase shift film on the transparent substrate, it took out from the chamber and washed the surface of the phase shift film with pure water. The pure water washing conditions were a temperature of 30 degrees and a washing time of 60 seconds.

Thereafter, an etching mask film 40 was formed by the same method as in Example 1.

In this way, the phase shift mask blank 10 in which the phase shift film 30 and the etching mask film 40 were formed on the transparent substrate 20 was obtained.

The transmittance and phase difference of the obtained phase shift mask blank 10 (a phase shift film obtained by washing the surface of the phase shift film with pure water) were measured using MPM-100 manufactured by Lasertec Co., Ltd. For the measurement of transmittance and phase difference of the phase shift film, a substrate (dummy substrate) provided with a phase shift film in which the phase shift film 30 was formed on the main surface of a synthetic quartz glass substrate prepared by setting on the same tray was used. The transmittance and phase difference of the phase shift film 30 were measured by taking out the substrate (dummy substrate) with the phase shift film from the chamber before forming the etching mask film. As a result, the transmittance was 33% (wavelength: 365 nm) and the phase difference was 169 degrees (wavelength: 365 nm).

Moreover, compositional analysis in the depth direction by X-ray photoelectron spectroscopy (XPS) was performed about the obtained phase shift mask blank.

As a result, as in Example 1, the phase shift film 30 has a composition gradient region at the interface between the transparent substrate 20 and the phase shift film 30, and the phase shift film 30 and the etching mask film 40 Except for the composition gradient region of the interface, the content of each constituent element was almost constant in the depth direction, Mo was 7 at%, Si was 38 at%, N was 45 at%, and O was 10 at%. Moreover, the atomic ratio of molybdenum and silicon was 1:5.4, and was within the range of 1:3 or more and 1:15 or less. In addition, the total content rate of oxygen, nitrogen, and carbon as light elements was 55 atomic%, and was within the range of 50 atomic% or more and 65 atomic% or less.

Next, as a result of cross-sectional SEM observation at a magnification of 80000 times at a position in the center of the transfer pattern formation region of the obtained phase shift mask blank 10, 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 have a columnar particle structure extending in the film thickness direction of the phase shift film 30 . And, as for the columnar grain structure of the phase shift film 30, it was confirmed that the columnar grains in the film thickness direction were formed irregularly, and the length of the columnar grains in the film thickness direction was not even. It was also confirmed that small portions of the phase shift film 30 were continuously formed in the film thickness direction. Further, with respect to the image obtained by this cross-sectional SEM observation, image data of 64 vertical pixels x 256 horizontal pixels was extracted for a region including the central portion in the thickness direction of the phase shift film 30 (Fig. 8(a) )). Further, Fourier transform was performed on the image data shown in Fig. 8(a) (Fig. 8(b)). In the spatial frequency spectrum distribution obtained by Fourier transform, the signal intensity (maximum signal intensity) at the origin of the spatial frequency is 2406000, and that apart from the maximum signal intensity, a spatial frequency spectrum having a signal intensity of 39240 exists. Confirmed. This is 39240/2406000 = 0.016 (ie, 1.6%) with respect to the maximum signal intensity corresponding to the origin of the spatial frequency, and the phase shift film 30 was a columnar structure having a signal intensity of 1.0% or more.

In addition, for the Fourier transform image of FIG. 8(b), the origin of the spatial frequency, that is, the center of the image of FIG. ), a signal having a signal intensity of 1.6% of the maximum signal intensity corresponding to the origin of the spatial frequency has a fine columnar structure having a signal at a position 0.023, that is, 2.3% away from the origin. 30) was.

Further, similarly to Example 1, dark field plane STEM observation was performed in the vicinity of the film thickness center of the phase shift film 30. As a result, it was confirmed that the particle portion of each columnar phase and the small portion were formed in the phase shift film 30 as in Example 1.

B. Phase shift mask and its manufacturing method

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 using the phase shift mask blank manufactured as described above. Wet etching with respect to the phase shift film 30 was performed with an over-etching time of 110% in order to form a fine pattern required for verticalizing the cross-sectional shape. Compared with the just etching time in the comparative example mentioned later, the just etching time in Example 2 became 0.07 times, and it was able to shorten etching time significantly.

A cross section of the obtained phase shift mask was observed with a scanning electron microscope. The angle of the cross section of the phase shift film pattern 30a of the phase shift mask was 74 degrees, and it had a cross section shape close to vertical. In addition, permeation was not seen in either of the interface with the etching mask film pattern and the interface with the substrate in the phase shift film pattern. Therefore, in exposure light containing light in a wavelength range of 300 nm or more and 500 nm or less, more specifically, exposure light of composite light including i-line, h-line, and g-line, a phase having an excellent phase shift effect A shift mask was obtained.

For this reason, when the phase shift mask of Example 2 is set on the mask stage of exposure apparatus and exposure transfer is carried out to the resist film on a display apparatus, it can be said that a fine pattern of less than 2.0 micrometer can be transferred with high precision.

In addition, in the cross-sectional SEM photograph of FIG. 9, in the phase shift mask manufacturing process of Example 2, the phase shift film 30 was wetted with a molybdenum silicide etchant using the first etching mask film pattern 40a as a mask. It is a cross-sectional SEM photograph after carrying out etching (over-etching of 110%), forming the phase shift film pattern 30a, and peeling off the resist film pattern. As shown in FIG. 9, the phase shift film pattern 30a maintains the columnar structure of the phase shift film 30, and the exposed surface of the transparent substrate 20 after removing the phase shift film 30 is It was smooth, and the decrease in transmittance due to surface roughness of the transparent substrate 20 was in a state where it could be ignored.

Example 3.

A. Phase Shift Mask Blanks and Manufacturing Methods Thereof

The phase shift mask blank of Example 3 is a phase shift mask blank that does not have an etching mask film in the phase shift mask blank of Example 1.

In order to manufacture the phase shift mask blank of Example 3, similarly to Example 1, the synthetic quartz glass substrate of 1214 size (1220 mm x 1400 mm) was prepared as the transparent substrate 20.

In order to form the phase shift film 30 on the main surface of the transparent substrate 20 using the same film formation method as in Example 1, argon (Ar ) gas, nitrogen (N ₂ ) gas, and helium (He) gas (Ar: 18 sccm, N ₂ : 13.5 sccm, He: 50 sccm) were introduced. Under these film formation conditions, a phase shift film 30 (film thickness: 150 nm) made of an oxynitride of molybdenum silicide was formed on the transparent substrate 20 .

In this way, the phase shift mask blank 10 in which the phase shift film 30 was formed on the transparent substrate 20 was obtained.

About the phase shift film of the obtained phase shift mask blank 10, the transmittance|permeability and phase difference were measured with MPM-100 by the Lasertech company. For the measurement of transmittance and phase difference of the phase shift film, a substrate (dummy substrate) provided with a phase shift film in which the phase shift film 30 was formed on the main surface of a synthetic quartz glass substrate prepared by setting on the same tray was used. As a result, the transmittance was 24% (wavelength: 405 nm) and the phase difference was 183 degrees (wavelength: 405 nm).

As a result of conducting a compositional analysis in the depth direction by X-ray photoelectron spectroscopy (XPS) about the phase shift film 30 of this obtained phase shift mask blank 10, as in Example 1, the phase shift film 30 , the content of each constituent element was almost constant in the depth direction. Moreover, the atomic ratio of molybdenum and silicon was 1:5, and was within the range of 1:3 or more and 1:15 or less. In addition, the total content rate of oxygen, nitrogen, and carbon as light elements was 52 atomic%, and was within the range of 50 atomic% or more and 65 atomic% or less. In addition, the content rate of oxygen was 0.3 atomic%, and was within the range of more than 0 atomic% and 40 atomic% or less.

Next, as a result of cross-sectional SEM observation at a magnification of 80000 times at a position in the center of the transfer pattern formation region of the obtained phase shift mask blank 10, it is confirmed that the phase shift film 30 has a columnar structure. It became. That is, it was confirmed that the particles of the molybdenum silicide compound constituting the phase shift film 30 have a columnar particle structure extending in the film thickness direction of the phase shift film 30 . And, as for the columnar grain structure of the phase shift film 30, it was confirmed that the columnar grains in the film thickness direction were formed irregularly, and the length of the columnar grains in the film thickness direction was not even. It was also confirmed that small portions of the phase shift film 30 were continuously formed in the film thickness direction. Further, with respect to the image obtained by this cross-sectional SEM observation, image data of 64 vertical pixels x 256 horizontal pixels was extracted for a region including the central portion in the thickness direction of the phase shift film 30 (Fig. 10(a) )). Further, Fourier transform was performed on the image data shown in Fig. 10(a) (Fig. 10(b)). In the spatial frequency spectrum distribution obtained by Fourier transform, the signal intensity (maximum signal intensity) at the origin of the spatial frequency is 31590000, and apart from the maximum signal intensity, a spatial frequency spectrum having a signal intensity of 47230 exists. Confirmed. This is 47230/3159000 = 0.015 (i.e., 1.5%) with respect to the maximum signal intensity corresponding to the origin of the spatial frequency, and the phase shift film 30 was a columnar structure having a signal intensity of 1.0% or more.

In addition, with respect to the Fourier transform image of FIG. 10 (b), the origin of spatial frequency, that is, the center of the image of FIG. ), a signal with a signal strength of 1.5% of the maximum signal strength corresponding to the origin of the spatial frequency has a fine columnar structure with a large spatial frequency having a signal at a position 0.078, that is, 7.8% away from the origin. It was the phase shift film 30 with.

Further, similarly to Example 1, dark field plane STEM observation was performed in the vicinity of the film thickness center of the phase shift film 30. As a result, as in Example 1, it was confirmed that the phase shift film 30 was formed with each columnar particle and a small portion.

B. Phase shift mask and its manufacturing method

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 using the phase shift mask blank 10 manufactured as described above. The wet etching with respect to the phase shift film 30 was performed with an over-etching time of 110% in order to form a fine pattern required for verticalizing the cross-sectional shape. Compared with the just etching time in the comparative example mentioned later, the just etching time in Example 3 was 0.20 times, and it was able to shorten etching time significantly.

A cross section of the obtained phase shift mask was observed with a scanning electron microscope. The angle of the cross section of the phase shift film pattern 30a of the phase shift mask was 80°, and had a cross sectional shape close to vertical. In addition, permeation was not seen in either of the interface with the etching mask film pattern and the interface with the substrate in the phase shift film pattern. Therefore, in exposure light containing light in a wavelength range of 300 nm or more and 500 nm or less, more specifically, exposure light of composite light including i-line, h-line, and g-line, a phase having an excellent phase shift effect A shift mask was obtained.

For this reason, when the phase shift mask of Example 3 is set on the mask stage of the exposure apparatus and exposed and transferred to the resist film on the display apparatus, it can be said that a fine pattern of less than 2.0 µm can be transferred with high precision.

In addition, in the cross-sectional SEM photograph of FIG. 11, in the manufacturing process of the phase shift mask of Example 3, the phase shift film 30 was wetted with a molybdenum silicide etchant using the first etching mask film pattern 40a as a mask. It is a cross-sectional SEM photograph after carrying out etching (over-etching of 110%), forming the phase shift film pattern 30a, and peeling off the resist film pattern. As shown in FIG. 11, the phase shift film pattern 30a maintains the columnar structure of the phase shift film 30, and the exposed surface of the transparent substrate 20 after removing the phase shift film 30 is It was smooth, and the transmittance due to the surface roughness of the transparent substrate 20 was in a state where it could be ignored. The line edge roughness was better compared to Example 1.

In addition, in the above-mentioned embodiment, the case where molybdenum was used as a transition metal was described, but the effect equivalent to the above is obtained also in the case of other transition metals.

In addition, although the example of the phase shift mask blank for display device manufacture and the phase shift mask for display device manufacture was demonstrated in the above-mentioned embodiment, it is not limited to this. The phase shift mask blank and phase shift mask of the present invention can also be applied to semiconductor device manufacture, MEMS manufacture, printed circuit boards, and the like. Further, the present invention can be applied also to a binary mask blank having a light-shielding film as a thin film for pattern formation or a binary mask having a light-shielding film pattern.

In addition, in the above-described embodiment, the size of the transparent substrate has been described as an example in which the size is 1214 (1220 mm x 1400 mm x 13 mm), but it is not limited to this. In the case of a phase shift mask blank for display device manufacture, a large transparent substrate is used, and the length of one side of the size of the transparent substrate is 300 mm or more. The size of the transparent substrate used for the phase shift mask blank for display device manufacture is 330 mm x 450 mm or more and 2280 mm x 3130 mm or less, for example.

In addition, in the case of phase shift mask blanks for semiconductor device manufacturing, MEMS manufacturing, and printed circuit boards, small size transparent substrates are used, and the size of the transparent substrate is 9 inches or less in length on one side. The size of the transparent substrate used for the phase shift mask blank of the said use is 63.1 mm x 63.1 mm or more and 228.6 mm x 228.6 mm or less, for example. Usually, 6025 size (152 mm × 152 mm) or 5009 size (126.6 mm × 126.6 mm) is used for semiconductor manufacturing and MEMS manufacturing, and 7012 size (177.4 mm × 177.4 mm) or 9012 size ( 228.6 mm × 228.6 mm) is used.

Comparative Example 1.

A. Phase Shift Mask Blanks and Manufacturing Methods Thereof

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

In the same manner as in Example 1, a synthetic quartz glass substrate was introduced into the chamber of an inline sputtering device. Then, with the sputtering gas pressure in the first chamber set to 0.5 Pa, a mixed gas of argon (Ar) gas and nitrogen (N ₂ ) gas (Ar: 30 sccm, N ₂ : 30 sccm) was introduced. Then, a sputtering power of 7.6 kW was applied to a first sputtering target containing molybdenum and silicon (molybdenum:silicon = 1:9), and reactive sputtering resulted in molybdenum, silicon, and nitrogen containing molybdenum, silicon, and nitrogen on the main surface of the transparent substrate. Nitride of molybdenum silicide to be deposited. In this way, a phase shift film having a film thickness of 144 nm was formed.

The indentation hardness of the phase shift film in Comparative Example 1 did not satisfy 18 GPa or more and 23 GPa or less.

Thereafter, an etching mask film was formed by the same method as in Example 1.

In this way, a phase shift mask blank in which a phase shift film and an etching mask film were formed on a transparent substrate was obtained.

About the phase shift film of the obtained phase shift mask blank, the transmittance|permeability and phase difference were measured with MPM-100 by the Lasertech company. For the measurement of transmittance and phase difference of the phase shift film, a substrate (dummy substrate) with a phase shift film in which a phase shift film was formed on the main surface of a synthetic quartz glass substrate prepared by setting on the same tray was used. The transmittance and phase difference of the phase shift film were measured by taking out the substrate (dummy substrate) with the phase shift film from the chamber before forming the etching mask film. As a result, the transmittance was 30% (wavelength: 405 nm) and the phase difference was 177 degrees (wavelength: 405 nm).

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

Next, as a result of cross-section SEM observation at a magnification of 80000 times at a position in the center of the transfer pattern formation region of the obtained phase shift mask blank 10, no columnar structure was confirmed in the phase shift film, and an ultra-fine It was confirmed that it was a crystal structure or an amorphous structure. About the image obtained by this cross-sectional SEM observation, about the area|region containing the center part of the thickness direction of the phase shift film 30, it extracted as image data of 64 vertical pixels x 256 horizontal pixels (FIG. 12(a)) . Further, Fourier transform was performed on the image data shown in Fig. 12(a) (Fig. 12(b)). In the spatial frequency spectrum distribution obtained by Fourier transform, the signal intensity (maximum signal intensity) at the origin of the spatial frequency is 2073000, no strong signal separate from the maximum intensity signal is identified, and a space having a signal intensity of 12600 There was only a spectrum of frequencies. This becomes 12600/2073000 = 0.006 (i.e., 0.6%) with respect to the maximum signal intensity corresponding to the origin of the spatial frequency, and the phase shift film 30 has an ultra-fine crystal structure that does not have a signal intensity of 1.0% or more, or It was an amorphous structure.

B. Phase shift mask and its manufacturing method

A phase shift mask was manufactured by the same method as in Example 1 using the phase shift mask blank manufactured as described above. Wet etching with respect to the phase shift film was performed with an over-etching time of 110% in order to form a fine pattern required for verticalizing the cross-sectional shape. The just etching time in Comparative Example 1 was 142 minutes, which was a long time.

In addition, in the cross-sectional SEM photograph of FIG. 13 , in the manufacturing process of the phase shift mask of the comparative example, the phase shift film 30 was wet-etched with a molybdenum silicide etchant using the first etching mask film pattern 40a as a mask ( It is a cross-sectional SEM photograph before carrying out 110% over-etching), forming the phase shift film pattern 30a, and peeling a resist film pattern. As shown in FIG. 13, the surface of the exposed transparent substrate 20 after removing the phase shift film 30 was rough and was in a cloudy state even visually. Accordingly, the decrease in transmittance due to the surface roughness of the transparent substrate 20 was significant.

For this reason, when the phase shift mask of Comparative Example 1 is set on the mask stage of the exposure apparatus and exposed and transferred to the resist film on the display apparatus, it is expected that it is impossible to transfer a fine pattern of less than 2.0 μm.

Hereinafter, other Examples 1 to 4 and other Comparative Examples 1 and 2 (hereinafter, sometimes simply referred to as each example) will be described in order to explain the embodiment of the present invention more specifically.

A. Phase Shift Mask Blanks and Manufacturing Methods Thereof

Other Examples 1 to 4 For each of the other Comparative Examples 1 and 2, in order to manufacture a phase shift mask blank, first, a synthetic quartz glass substrate of 1214 size (1220 mm x 1400 mm) was prepared as the transparent substrate 20. did

After that, in each case, the synthetic quartz glass substrate was mounted on a tray (not shown) with the main surface facing downward, and was carried into the chamber of the inline type sputtering device.

In order to form the phase shift film 30 on the main surface of the transparent substrate 20, first, in the first chamber, a mixed gas containing argon (Ar) gas, helium (He) gas, and nitrogen (N ₂ ) gas. was introduced. The sputtering gas pressure at the time of introduction is adjusted by adjusting the flow rates of argon (Ar) gas, helium (He) gas, and nitrogen (N ₂ ) gas within a range in which the phase shift film satisfies the predetermined transmittance and phase difference, Different values were used in each case (see Table 1 below). As shown in Table 1, the sputtering gas pressure in each of the other Examples 1 to 4 satisfies the range of 0.7 Pa or more and 2.4 Pa or less, and the sputtering gas pressure in the other Comparative Examples 1 and 2 was 0.7 The range of Pa or more and 2.4 Pa or less was not satisfied. Then, in each case, a sputtering power of 7.6 kW was applied to a first sputter target containing molybdenum and silicon (molybdenum:silicon = 1:9), and reactive sputtering was performed on the main surface of the transparent substrate 20. A nitride of molybdenum silicide containing molybdenum, silicon, and nitrogen was deposited thereon to form a phase shift film 30. In each case, the film thickness of the phase shift film 30 was 144 nm - 170 nm.

Next, in each example, the transparent substrate 20 with the phase shift film 30 is carried into the second chamber, and a mixed gas of argon (Ar) gas and nitrogen (N ₂ ) gas is introduced into the second chamber. introduced. Then, a sputtering power of 1.5 kW was applied to the second sputter target made of chromium, and chromium nitride (CrN) containing chromium and nitrogen was formed on the phase shift film 30 by reactive sputtering (film thickness 15 nm). Next, with the inside of the third chamber at a predetermined vacuum level, a mixed gas of argon (Ar) gas and methane (CH ₄ : 4.9%) gas is introduced, and sputtering of 8.5 kW is performed on the third sputter target made of chromium. Power was applied, and chromium carbide (CrC) containing chromium and carbon was formed on CrN by reactive sputtering (film thickness: 60 nm). Finally, in a state where the inside of the fourth chamber has a predetermined degree of vacuum, a mixed gas of argon (Ar) gas and methane (CH ₄ : 5.5%) gas, nitrogen (N ₂ ) gas, and oxygen (O ₂ ) gas are mixed A gas was introduced, and a sputtering power of 2.0 kW was applied to a fourth sputter target made of chromium, and chromium carbonized oxynitride (CrCON) containing chromium, carbon, oxygen, and nitrogen was formed on CrC by reactive sputtering ( film thickness 30 nm). As described above, in each example, the etching mask film 40 having a laminated structure of a CrN layer, a CrC layer, and a CrCON layer was formed on the phase shift film 30 .

In this way, in each example, the phase shift mask blank 10 in which the phase shift film 30 and the etching mask film 40 were formed on the transparent substrate 20 was obtained.

In each case, about the surface of the phase shift film 30 (phase shift film 30) of the obtained phase shift mask blank 10, the transmittance|permeability and the phase difference were measured with MPM-100 by Lasertec Corporation. In the measurement of the transmittance and phase difference of the phase shift film 30, a substrate (dummy substrate) provided with a phase shift film in which the phase shift film 30 is formed on the main surface of a synthetic quartz glass substrate prepared by setting it on the same tray. was used. In each case, the transmittance and phase difference of the phase shift film 30 were measured by taking out the substrate (dummy substrate) with the phase shift film from the chamber before forming the etching mask film 40 . As a result, in each case, transmittance and phase difference both satisfied the required range (transmittance: 10 to 50% at a wavelength of 405 nm, phase difference: 160° or more and 200° or less at a wavelength of 405 nm).

Moreover, in each case, compositional analysis in the depth direction by X-ray photoelectron spectroscopy (XPS) was performed about the phase shift mask blank 10 obtained.

In each case, in the composition analysis result of the depth direction by XPS for the phase shift mask blank 10, the phase shift film 30 is the composition of the interface between the transparent substrate 20 and the phase shift film 30. Except for the gradient region and the composition gradient region of the interface between the phase shift film 30 and the etching mask film 40, the content of each constituent element was substantially constant toward the depth direction. Moreover, in each case, the atomic ratio of molybdenum and silicon was within the range of 1:3 or more and 1:15 or less.

And in each case, the indentation hardness of the obtained phase shift film 30 was measured. Specifically, the phase shift film 30 in each example is set to a 6x6 matrix position (36 positions) with a pitch of 50 µm, and a special probe equipped with a diamond indenter at each position is set to a maximum of 0.5 By indenting in mN, the change in load was measured. From the measured values obtained at each position, the indentation hardness in each case was calculated by removing the abnormal value, the maximum value, and the minimum value (see Table 1). In addition, it was confirmed that the standard deviation of the measured values became 7% or less of the measured values by removing the outliers, the maximum value, and the minimum value.

As shown in Table 1, the indentation hardness in other Examples 1 to 4 satisfies 18 GPa or more and 23 GPa or less, and the indentation hardness in other Comparative Examples 1 and 2 does not satisfy 18 GPa or more and 23 GPa or less. it was

B. Phase shift mask and its manufacturing method

In order to manufacture the phase shift mask 100 using the phase shift mask blank 10 manufactured as described above, first, in each example, on the etching mask film 40 of the phase shift mask blank 10 , a photoresist film was applied using a resist coating device.

Thereafter, a photoresist film having a film thickness of 520 nm was formed through a heating/cooling process.

Thereafter, the photoresist film was drawn using a laser drawing device, and a resist film pattern of a hole pattern having a hole diameter of 1.5 μm was formed on the etching mask film through a developing and rinsing process.

Thereafter, in each example, using the resist film pattern as a mask, the etching mask film was wet-etched with a chromium etching solution containing ceric ammonium nitrate and perchloric acid to form a first etching mask film pattern 40a.

Then, in each example, the phase shift film 30 is wet-etched with a molybdenum silicide etchant obtained by diluting a mixed solution of ammonium hydrogen fluoride and hydrogen peroxide with pure water using the first etching mask film pattern 40a as a mask. , the phase shift film pattern 30a was formed.

This wet etching was performed at an over-etching time of 110% in each case in order to form a fine pattern required for verticalizing the cross-sectional shape.

Table 1 shows the etching rate of the phase shift film 30 in each case. As shown in Table 1, the etching rate in Comparative Example 1 was the smallest at 1.0 nm/min, and the etching rate in Comparative Example 2 was the largest at 12.0 nm/min.

After that, the resist film pattern was peeled off.

Then, in each example, a photoresist film was applied using a resist coating device so as to cover the first etching mask film pattern 40a.

Thereafter, a photoresist film having a film thickness of 520 nm was formed through a heating/cooling process.

Thereafter, a photoresist film is drawn using a laser drawing device, and a second resist film pattern 60 for forming a light-shielding band is formed on the first etching mask film pattern 40a through a developing and rinsing process. did

Thereafter, using the second resist film pattern 60 as a mask, the first etching mask film pattern 40a formed in the transfer pattern forming region was wet etched with a chromium etching solution containing ceric ammonium nitrate and perchloric acid. .

After that, the second resist film pattern 60 was peeled off.

Further, in each case, cleaning treatment using a chemical solution (sulfuric acid fruit water (SPM), ammonia fruit water (SC1), or ozone water) was appropriately performed.

In this way, in each example, on the transparent substrate 20, the phase shift film pattern 30a having a hole diameter of 1.5 μm in the transfer pattern formation region, the phase shift film pattern 30a, and the etching mask film pattern ( The phase shift mask 100 with the light-shielding band which consists of the laminated structure of 40b) was obtained.

Table 1 shows the etching rate of the sputtering gas pressure (Pa) and the phase shift film 30 (nm/ minutes), the indentation hardness (GPa) of the phase shift film 30, the presence or absence of surface roughness of the transparent substrate 20 by wet etching, and the results of the cleaning resistance of the phase shift film 30, respectively.

14 shows the relationship between the etching rate, the sputtering gas pressure, and the indentation hardness in the phase shift film 30 of the phase shift mask 100 of the other Examples 1 to 4 and the other Comparative Examples 1 and 2 is a graph that represents 14, from left to right (in order of decreasing etching rate), Comparative Example 1, Example 4, Example 3, Example 2, Example 1, and Comparative Example 2 Indentation hardness and sputtering gas pressure are shown. As shown in FIG. 14, it turned out that the correlation was seen between the etching rate in the phase shift film 30, and indentation hardness or sputtering gas pressure.

A cross section of the obtained phase shift mask was observed with a scanning electron microscope. The cross section of the phase shift film pattern is constituted by the upper surface, lower surface and side surface of the phase shift film pattern. The angle of the cross section of this phase shift film pattern refers to the angle formed by the part where the upper surface and side surface of a phase shift film pattern contact (upper edge) and the part where the side surface and lower surface contact each other (lower edge). As a result, the cross-sectional shape of the phase shift film pattern 30a of the phase shift mask of the other Examples 1 to 4 and the other Comparative Example 2 is in the range of 65° to 75°, and both cross-sections can sufficiently exhibit the phase shift effect. had a shape The surface of the exposed transparent substrate 20 of the phase shift mask 100 in other Examples 1 to 4 was smooth, and the decrease in transmittance due to the surface roughness of the transparent substrate 20 was in a state where it could be ignored. Therefore, in exposure light containing light in a wavelength range of 300 nm or more and 500 nm or less, more specifically, exposure light of composite light including i-line, h-line, and g-line, a phase having an excellent phase shift effect A shift mask was obtained.

For this reason, when the phase shift masks of other Examples 1 to 4 are set on the mask stage of the exposure device and exposed and transferred to the resist film on the display device, it can be said that fine patterns of less than 2.0 μm can be transferred with high precision. .

Moreover, in all the phase shift film patterns 30a of the phase shift mask 100 in other Examples 1-4, a columnar structure was seen.

On the other hand, the surface of the exposed transparent substrate 20 of the phase shift mask 100 in the other comparative example 1 was rough, and was in a cloudy state even visually. Accordingly, the decrease in transmittance due to the surface roughness of the transparent substrate 20 was significant.

For this reason, when the phase shift mask 100 of Comparative Example 1 is set on the mask stage of the exposure device and exposed and transferred to the resist film on the display device, it is expected that it is impossible to transfer a fine pattern of less than 2.0 μm. .

Moreover, the surface of the exposed transparent substrate 20 of the phase shift mask 100 in another comparative example 2 was smooth, and the transmittance|permeability fall by the surface roughness of the transparent substrate 20 was in a state which could be ignored. However, the amount of change in transmittance and the amount of change in phase difference due to the chemicals (sulfuric acid fruit water (SPM), ammonia fruit water (SC1), ozone water) used in cleaning the phase shift mask 100 are large, so that the phase shift mask 100 requires The transmittance and the phase difference were not satisfied.

For this reason, when the phase shift mask of Comparative Example 2 was set on the mask stage of the exposure apparatus and exposed and transferred to the resist film on the display apparatus, it is expected that it is impossible to transfer a fine pattern of less than 2.0 μm.

In addition, the columnar structure was not seen in the phase shift film pattern 30a of the phase shift mask 100 in the other comparative example 1. It was the same also in the phase shift film pattern 30a of the phase shift mask 100 in the other comparative example 2.

10: phase shift mask blank
20: transparent substrate
30: phase shift film
30a: phase shift film pattern
40: etching mask film
40a: first etching mask film pattern
40b: second etching mask film pattern
50: first resist film pattern
60: second resist film pattern
100: phase shift mask

Claims (9)

A photomask blank having a thin film for pattern formation on a transparent substrate,
The photomask blank is an original plate for forming a photomask having a transfer pattern on the transparent substrate by wet etching the thin film for pattern formation,
The thin film for pattern formation contains a transition metal, silicon, and nitrogen, and the atomic ratio of the transition metal and the silicon included in the thin film for pattern formation is transition metal:silicon = 1:3 or more 1:15. below,
The thin film for pattern formation is a photomask blank, characterized in that the indentation hardness derived by the nanoindentation method is 18 GPa or more and 23 GPa or less. According to claim 1,
The transition metal is a photomask blank, characterized in that molybdenum. According to claim 1,
The photomask blank, characterized in that the nitrogen content is 35 atomic% or more and 60 atomic% or less. According to claim 1,
The thin film for pattern formation is a phase shift film having optical characteristics of a transmittance of 1% or more and 80% or less and a phase difference of 160° or more and 200° or less with respect to a representative wavelength of exposure light Photomask blank. According to claim 1,
A photomask blank comprising an etching mask film having a different etching selectivity with respect to the thin film for pattern formation, on the thin film for pattern formation. According to claim 5,
The photomask blank according to claim 1, wherein the etching mask film is made of a material containing chromium and substantially not containing silicon. A step of preparing the photomask blank according to claim 1;
A step of forming a resist film on the thin film for pattern formation, wet etching the thin film for pattern formation using the resist film pattern formed from the resist film as a mask, and forming a transfer pattern on the transparent substrate. A method for manufacturing a photomask. A step of preparing the photomask blank according to claim 5;
forming a resist film on the etching mask film, wet-etching the etching mask film using the resist film pattern formed from the resist film as a mask, and forming an etching mask film pattern on the pattern forming thin film;
and wet-etching the thin film for pattern formation using the etching mask film pattern as a mask, and forming a transfer pattern on the transparent substrate. A photomask obtained by the photomask manufacturing method according to claim 7 or 8 is loaded on a mask stage of an exposure apparatus, and the transfer pattern formed on the photomask is exposed and transferred to a resist formed on a display device substrate. A method for manufacturing a display device comprising an exposure step of

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