KR20240017031A - Photomask blank, method for manufacturing photomask, and method for manufacturing display device - Google Patents

Abstract

[Problem] To provide a photomask blank that can shorten the over-etching time and form a transfer pattern with a good cross-sectional shape when forming a transfer pattern on a thin film for pattern formation by wet etching.
[Solution] A photomask blank having a thin film for pattern formation on a transparent substrate. The photomask blank is a raw plate for forming a photomask with a transfer pattern on a transparent substrate by wet etching the thin film for pattern formation, A photomask blank characterized in that the thin film for pattern formation contains a transition metal and silicon, and the thin film for pattern formation has a columnar structure.

Description

Photomask blank, photomask manufacturing method, and display device manufacturing method {PHOTOMASK BLANK, METHOD FOR MANUFACTURING PHOTOMASK, AND METHOD FOR MANUFACTURING DISPLAY DEVICE}

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

In recent years, in display devices such as LCD (Liquid Crystal Display) and FPD (Flat Panel Display), high-precision and high-speed display, along with large screens and wide viewing angles, are rapidly progressing. One of the elements necessary for this high-precision, high-speed display is the production of electronic circuit patterns, such as elements and wiring, that are fine and have high dimensional accuracy. Photolithography is often used for patterning electronic circuits for these display devices. For this reason, photomasks such as phase shift masks and binary masks for manufacturing display devices on which fine, high-precision patterns are formed are 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 the i-line (365 nm), the h-line (405 nm), and the g-line (436 nm). It is a metal silicide compound containing at least one light element of oxygen (O), nitrogen (N), and carbon (C) so that it has a transmittance of % and the slope of the pattern cross-section is sharply formed during pattern formation. It is composed of a multilayer film of two or more layers, and the metal silicide compound is formed by injecting a reactive gas containing the light element material and an inert gas at a ratio of 0.5:9.5 to 4:6.

In addition, Patent Document 2 discloses a phase shift mask blank including a transparent substrate, a light semitransmissive film made of a metal silicide-based material and having the property of changing the phase of exposure light, and an etching mask film made of a chromium-based material. It is done. 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 proportion of components that slow down the wet etching rate of the light semitransmissive film increases toward the depth direction. And, the oxygen content in the composition gradient region is 10 atomic% or less.

Korea Registered Patent No. 1801101 Patent No. 6101646

The phase shift mask used in recent high-precision (1000 ppi or more) panel production is a phase shift mask to enable high-resolution pattern transfer, and also has a fine hole diameter of 6 μm or less and a line width of 4 μm or less. There is a demand for a phase shift mask with a phase shift film pattern formed thereon. 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 of 15% or more to the exposure light and a phase shift mask formed with a phase shift film pattern having a transmittance to the exposure light of 15% or more are provided. It is being demanded. In addition, regarding the cleaning resistance (chemical properties) of the phase shift mask blank or phase shift mask, the phase has cleaning resistance with suppressed changes in optical properties due to film reduction of the phase shift film or phase shift film pattern or change in surface composition. A phase shift mask blank with a shift film formed thereon and a phase shift mask with a phase shift film pattern having cleaning resistance are required.

In order to satisfy the requirements for transmittance to exposure light and 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 it is effective, there is a problem in that the wet etching speed is significantly slowed down (wet etching time becomes longer), and damage to the substrate occurs due to the wet etching solution, resulting in a decrease in the transmittance of the transparent substrate.

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

Therefore, the present invention was made to solve the above-mentioned problem, and the object of the present invention is to form a transfer pattern by wet etching on a pattern forming thin film such as a phase shift film or light-shielding film containing a transition metal and silicon. , a photomask blank that can shorten the wet etching time and form a transfer pattern with a good cross-sectional shape, a method of manufacturing the photomask blank, a method of manufacturing a photomask, and a method of manufacturing a display device.

The present inventor has carefully studied measures to solve 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 transition metal:silicon is 1:3 or more, and in order to shorten the wet etching time by a wet etchant in the thin film for pattern formation, The thin film for pattern formation was formed by adjusting the oxygen gas contained 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 speed for forming the transfer pattern became faster, the refractive index of the exposure light decreased in the phase shift film in the phase shift mask blank, so the desired phase difference (for example, 180°) was reduced. The film thickness required to obtain it becomes thicker. In addition, in the light-shielding film in the binary mask blank, the extinction coefficient for exposure light decreases, so the film thickness required to obtain the desired light-shielding performance (e.g., optical density (OD) of 3 or more) becomes thick. . Increasing the film thickness of the thin film for pattern formation is disadvantageous in pattern formation by wet etching, and because the film thickness is thick, there is a limit to the effect of shortening the wet etching time. On the other hand, the atomic ratio of the transition metal and silicon (transition metal: silicon = 1:3 or more) as described above has the advantage of increasing the cleaning resistance of the thin film for pattern formation, so in this regard as well, the transition metal as described above It is not desirable to deviate from the composition ratio of and silicon.

Therefore, the present inventor changed the idea and considered 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, the sputtering gas pressure in the film formation chamber is usually set to 0.1 to 0.5 Pa. However, the present inventor intentionally set the sputtering gas pressure greater than 0.5 Pa to form a thin film for pattern formation. In addition, the thin film for pattern formation was deposited at a sputtering pressure of 0.7 Pa or more and 3.0 Pa or less, and preferably at a sputtering gas pressure of 0.8 Pa or more and 3.0 Pa or less, so that it not only has suitable characteristics as a thin film, but also can be used as a thin film for pattern formation. It was found that when forming a transfer pattern by wet etching, the etching time can be significantly shortened and a transfer pattern with a good cross-sectional shape can be formed. And, the thin film for pattern formation formed into a film in this way had a columnar structure that is not visible in ordinary thin films for pattern formation. The present invention was made as a result of the above-mentioned studies, and has the following structure.

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

The photomask blank is a raw plate for forming a photomask with a transfer pattern on the transparent substrate by wet etching the pattern forming thin film,

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

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

(Configuration 2) The thin film for forming the pattern is,

For the image obtained by scanning electron microscope observation of the cross section of the photomask blank at a magnification of 80,000 times, image data of 64 pixels vertically and 256 pixels horizontally for the area including the center of the thickness direction of the thin film for pattern formation. In the spatial frequency spectrum distribution obtained by extracting and 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. Photomask blank described in 1.

(Configuration 3) The pattern forming thin film is in configuration 2, wherein the signal having a signal intensity of 1.0% or more is at a spatial frequency that is 2.0% or more away from the origin of the spatial frequency when the maximum spatial frequency is set to 100%. Photomask blank listed.

(Configuration 4) The photomask according to any one of Configurations 1 to 3, wherein the atomic ratio of the transition metal and the silicon contained in the pattern forming thin film 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 pattern forming thin film 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 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 of 18 GPa or more and 23 GPa or less as determined by the nanoindentation method.

(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) Configurations 1 to 1, wherein the thin film for pattern formation is a phase shift film having optical properties such as a transmittance of 1% to 80% and a phase difference of 160° to 200° for 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 of manufacturing 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 uses a transition metal silicide target containing a transition metal and silicon in a deposition chamber, and is formed at a sputtering gas pressure of 0.7 Pa or more and 3.0 Pa or less in the deposition chamber to which sputtering gas is supplied. Method for manufacturing a photomask blank.

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

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

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

(Configuration 16) A process of preparing a photomask blank according to any of Configurations 1 to 9, or a photomask blank manufactured by the method for producing a photomask blank according to Configurations 12 or 13;

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

(Configuration 17) A process of preparing a photomask blank according to Configuration 10 or 11, or a photomask blank manufactured by the method for producing a photomask blank according to Configuration 14 or 15;

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

A method of manufacturing a photomask, comprising the steps of using the etching mask film pattern as a mask, wet etching the pattern forming thin film, and forming a transfer pattern on the transparent substrate.

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

Additionally, the present inventor 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 set the sputtering gas pressure to be greater than 0.5 Pa and formed 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 with a good cross-sectional shape can be formed, and surface roughness of the transparent substrate can be suppressed. found out. On the other hand, it was found that if the sputtering gas pressure during film formation was too large, sufficient cleaning resistance could not be obtained in the thin film for pattern formation. As a result of intensive study, the present inventors have found that by forming a pattern-forming thin film at a sputtering gas pressure of 0.7 Pa or more and 2.4 Pa or less, a transfer pattern that not only has suitable characteristics as a pattern-forming thin film but also has a good cross-sectional shape can be formed. It was 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 increased.

In addition, the present inventor further explored the physical indicators of thin films for pattern formation having such excellent characteristics. As a result, it was found that there was a correlation between the indentation hardness of the thin film for pattern formation and the wet etching rate. As a result of further careful examination of this point, it was found that if the indentation hardness derived by the nanoindentation method is 18 GPa or more and 23 GPa or less, it has suitable characteristics as a thin film for pattern formation, and the transfer pattern can be applied to the thin film for pattern formation by wet processing. It was found that when formed by etching, a transfer pattern with a good cross-sectional shape can be formed, and the surface roughness of the transparent substrate can be suppressed and the cleaning resistance of the thin film for pattern formation can be increased.

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

The photomask blank is a raw plate for forming a photomask with a transfer pattern on the transparent substrate by wet etching the pattern forming thin film,

The thin film for pattern formation contains a transition metal, silicon, and nitrogen, and the atomic ratio of the transition metal and silicon contained 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.

(Other Configuration 2) The photomask blank according to Other 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) Another configuration characterized in that the thin film for pattern formation is a phase shift film having optical properties such as a transmittance of 1% to 80% and a phase difference of 160° to 200° for a representative wavelength of exposure light. The photomask blank according to any one of 1 to 3.

(Other Configuration 5) The photomask blank according to any of the other configurations 1 to 4, 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.

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

(Other Configuration 7) A process of preparing a photomask blank according to any of the other configurations 1 to 4;

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

(Other Configuration 8) A process of preparing a photomask blank according to Other Configuration 5 or 6;

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

A method of manufacturing a photomask, comprising the steps of using the etching mask film pattern as a mask, wet etching the pattern forming thin film, and forming a transfer pattern on the transparent substrate.

(Other Configuration 9) The photomask obtained by the photomask manufacturing method according to Other Configuration 7 or 8 is placed on the mask stage of an exposure apparatus, and the transfer pattern formed on the photomask is applied to the resist formed on the display device substrate. A method of manufacturing a display device, comprising an exposure process of exposure and transfer to .

According to the photomask blank or the manufacturing method of the photomask blank according to the present invention, when forming the fine transfer pattern required by wet etching the thin film for transfer pattern, the thin film for pattern formation is rich in silicon in terms of cleaning resistance, etc. Even when made of a metal silicide compound, there is no decrease in the transmittance of the transparent substrate due to damage to the substrate by the wet etching solution, and a photomask blank is capable of forming a transfer pattern with a good cross-sectional shape in a short etching time. You can get it. In addition, according to the photomask blank according to another configuration of the present invention, when forming a required fine transfer pattern by wet etching a thin film for a transfer pattern, a transfer pattern with a good cross-sectional shape can be formed, and the transfer pattern can be formed on a transparent substrate. A photomask blank can be obtained that can suppress surface roughness and increase the cleaning resistance of the thin film for the transfer pattern.

Additionally, according to the photomask manufacturing method 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 viewpoint of cleaning resistance, etc., 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 with a transfer pattern can be manufactured. This photomask can cope with the 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, it is possible to form a transfer pattern with a good cross-sectional shape, suppress the surface roughness of the transparent substrate, and improve the cleaning resistance of the thin film for the transfer pattern. A photomask that can be raised can be manufactured.

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

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

Embodiment 1. 2.

In Embodiments 1 and 2, the phase shift mask blank is explained. 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. This is the original version for In addition, 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's the original.

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

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.

FIG. 2 is a schematic diagram showing the film structure of the phase shift mask blank 10 according to Embodiment 2.

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

Hereinafter, the transparent substrate 20, phase shift film 30, and etching mask film 40 that constitute the phase shift mask blank 10 of Embodiment 1 and Embodiment 2 will be described.

The transparent substrate 20 is transparent to exposure light. The transparent substrate 20 has a transmittance of 85% or more, preferably 90% or more, to the exposure light, assuming no surface reflection loss. The transparent substrate 20 is made of a material containing silicon and oxygen, and is made of glass materials such as synthetic quartz glass, quartz glass, aluminosilicate glass, soda lime glass, and low thermal expansion glass (SiO ₂ -TiO ₂ glass, etc.) It can be configured as: When the transparent substrate 20 is made of low thermal expansion glass, a change in the position 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 devices is generally a rectangular substrate, and the short side length of the transparent substrate is 300 mm or more. The present invention provides a phase shift mask that can stably transfer a fine phase shift film pattern of less than 2.0 μm formed on a transparent substrate even if the short side length of the transparent substrate is large, such as 300 mm or more. It is a shift mask blank.

The phase shift film 30 is made of a transition metal and a transition metal silicide-based material containing silicon. As a transition metal, molybdenum (Mo), tantalum (Ta), tungsten (W), titanium (Ti), zirconium (Zr), etc. 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, oxygen, which is a light element component, has the effect of lowering the extinction coefficient compared to nitrogen, which is also a light element component, so other light element components (nitrogen, etc.) are used to obtain the desired transmittance. Not only can the content be reduced, but the reflectance of the front and back surfaces of the phase shift film 30 can also be effectively reduced. Additionally, in the transition metal silicide-based material, nitrogen, which is a light element component, has the effect of not lowering the refractive index compared to oxygen, which is also a light element component, so the film thickness for obtaining the desired phase difference can be thinned. there is. Additionally, the total content of light elements including oxygen and nitrogen contained in the phase shift film 30 is preferably 40 atomic% or more. More preferably, it is 40 atomic% or more and 70 atomic% or less, and 50 atomic% or more and 65 atomic% or less. In addition, when oxygen is contained in the phase shift film 30, it is preferable that the oxygen content is more than 0 atomic% and 40 atomic% or less in terms of defect quality and chemical resistance.

Examples of transition metal silicide-based materials 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), a zirconium silicide-based material (ZrSi-based material), or a molybdenum zirconium silicide-based material (MoZrSi-based material), an excellent pattern cross-sectional shape can be achieved by wet etching. It is preferable because it is easy to obtain, and it is especially preferable if it is a molybdenum silicide-based material (MoSi-based material).

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

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

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

This phase shift film 30 preferably has a columnar structure. This columnar structure can be confirmed by cross-sectional SEM observation of the phase shift film 30. That is, the columnar structure in the present invention is such that the particles of the transition metal silicide compound containing the transition metal and silicon constituting the phase shift film 30 are deposited in the film thickness direction of the phase shift film 30 (the particles are deposited thereon). refers to a state of having a columnar particle structure that extends in the same direction. In addition, in this application, columnar particles are those whose length in the film thickness direction is longer than their length in the vertical direction. That is, the phase shift film 30 is formed of columnar particles extending in the film thickness direction over the surface of the transparent substrate 20 . In addition, in the phase shift film 30, by adjusting the film formation conditions (sputtering pressure, etc.), a small part (hereinafter sometimes simply referred to as a “small part”) with a relatively lower density than the main phase particles is formed. . In addition, in order to effectively suppress side etching during wet etching and further improve the pattern cross-sectional shape, the preferred form of the columnar structure of the phase shift film 30 is a structure extending in the film thickness direction. It is preferable that the columnar particles are formed irregularly in the film thickness direction. More preferably, the columnar particles of the phase shift film 30 preferably have an uneven length in the film thickness direction. And, it is preferable that the small portion of the phase shift film 30 is formed continuously in the film thickness direction. In addition, it is preferable that the small portion of the phase shift film 30 is formed intermittently in the direction perpendicular to the film thickness direction. A preferable form of the columnar structure of the phase shift film 30 can be expressed as follows using an index obtained by Fourier transformation of the image obtained by the cross-sectional SEM observation. In other words, the columnar structure of the phase shift film 30 is an area including the center of the phase shift film 30 in the thickness direction in an image obtained by cross-sectional SEM observation of the cross section of the phase shift mask blank at a magnification of 80000 times. is extracted as image data of 64 pixels vertically and 256 pixels horizontally, and the spatial frequency spectrum obtained by Fourier transforming 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. It is desirable to be in this state. By making the phase shift film 30 have the above-described columnar structure, during wet etching using a wet etching solution, the wet etching solution becomes easier to penetrate in the film thickness direction of the phase shift film 30, so the wet etching speed is increased, and wet etching Time can be drastically shortened. Therefore, even if the phase shift film 30 is a silicon-rich metal silicide compound, there is no decrease in the transmittance of the transparent substrate due to damage to the substrate by the wet etching solution. Additionally, since the phase shift film 30 has a columnar structure extending in the film thickness direction, side etching during wet etching is suppressed, and the pattern cross-sectional shape is improved.

In addition, 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 a signal with an intensity signal of 1.0% or more relative to the maximum signal intensity is separated by 2.0% or more indicates that it contains a spatial frequency component that is higher than a certain level. That is, the phase shift film 30 shows a state of having a fine columnar structure, and the farther the spatial frequency is from the origin, the more the phase shift film pattern 30a obtained by forming the phase shift film 30 by wet etching. This is desirable because the line edge roughness of is reduced.

The indentation hardness of this phase shift film 30 is preferably 18 GPa or more and 23 GPa or less. This indentation hardness is a hardness measured using the principles of the nanoindentation method established in ISO14577.

By setting the indentation hardness of the phase shift film 30 to 18 GPa or more and 23 GPa or less, during wet etching using a wet etching solution, the wet etching solution becomes easy to penetrate in the film thickness direction of the phase shift film 30, so the wet etching speed becomes faster. , wet etching time can be shortened. In addition, in addition to having suitable characteristics as the phase shift film 30, it is possible to form the phase shift film pattern 30a with a good cross-sectional shape, and the surface roughness of the transparent substrate 20 can be suppressed. , the cleaning resistance of the phase shift film 30 can be increased.

The atomic ratio of the transition metal and silicon contained in the phase shift film 30 is preferably transition metal:silicon=1:3 or more and 1:15 or less. Within this range, the effect of suppressing a decrease in the wet etching rate during pattern formation of the phase shift film 30 by the columnar structure can be increased. Additionally, the cleaning resistance of the phase shift film 30 can be improved, and it becomes easy to increase the transmittance. Moreover, within this range, the effect of suppressing a decrease in the wet etching rate during pattern formation of the phase shift film 30 by setting the indentation hardness to 18 GPa or more and 23 GPa or less can be increased. At the point of increasing the cleaning resistance of the phase shift film 30, the atomic ratio of the 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 is preferable.

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

Transmittance can be measured using a phase shift measurement device or the like.

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

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

The back surface reflectance of the phase shift film 30 is 15% or less in the wavelength range of 365 nm to 436 nm, and is preferably 10% or less. In addition, the back surface reflectance of the phase shift film 30 is preferably 20% or less, and more preferably 17% or less for light in the wavelength range of 313 nm to 436 nm when the exposure light includes the j line. More preferably, it is 15% or less. In addition, the back surface reflectance of the phase shift film 30 is preferably 0.2% or more in the wavelength range of 365 nm to 436 nm, and is preferably 0.2% or more for light in the 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 comprised of a plurality of layers, or may be comprised of a single layer. The phase shift film 30 comprised of a single layer is preferable because it is difficult for an interface to be formed in the phase shift film 30 and the cross-sectional shape is easy to control. On the other hand, the phase shift film 30 composed of a plurality of layers is preferable in terms of ease of film formation.

The etching mask film 40 is disposed above the phase shift film 30 and is made of a material that has etching resistance to the etchant that etches the phase shift film 30 (an etching selectivity is different from that of the phase shift film 30). It consists of In addition, the etching mask film 40 may have a function of blocking the transmission of exposure light, and the film surface reflectance of the phase shift film 30 with respect to the light incident from the phase shift film 30 side is 350 nm to 350 nm. It may have a function to reduce 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). More specifically, chromium-based materials include chromium (Cr) or materials containing at least one of chromium (Cr), oxygen (O), nitrogen (N), and carbon (C). Alternatively, a material containing at least one of chromium (Cr), oxygen (O), nitrogen (N), and carbon (C), and also containing fluorine (F) can be mentioned. 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 a sputtering method.

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

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

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

Moreover, the phase shift mask blank 10 shown in FIG. 1 is provided with the etching mask film 40 on the phase shift film 30, but is provided with the etching mask film 40 on the phase shift film 30. The present invention can also be applied to a phase shift mask blank provided with a resist film on the etching mask film 40.

Next, the manufacturing method of the phase shift mask blank 10 of the first and second embodiments will be described. 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 a phase shift film forming process.

Hereinafter, each process will be described in detail.

1. Phase shift film formation process

First, prepare a transparent substrate 20. The transparent substrate 20 is made of any glass material such as synthetic quartz glass, quartz glass, aluminosilicate glass, soda lime glass, low thermal expansion glass (SiO ₂ -TiO ₂ glass, etc.), as long as it is transparent to exposure light. It can be anything.

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

The phase shift film 30 is formed using a transition metal silicide target containing a transition metal and silicon as the main components of the material constituting the phase shift film 30, or a transition metal silicide target containing a transition metal, silicon, oxygen, and/or nitrogen. A transition metal silicide target is used as a sputter target, for example, a sputter gas atmosphere consisting 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, or the above. It is performed in a sputter gas atmosphere consisting 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 when the gas pressure in the film formation chamber when sputtering is performed is 0.7 Pa or more and 3.0 Pa or less. Preferably, the phase shift film 30 is formed at a gas pressure in the film formation chamber of 0.8 Pa or more and 3.0 Pa when sputtering is performed. By setting the gas pressure range in this way, a columnar structure can be formed in the phase shift film 30. With this columnar structure, side etching during pattern formation, which will be described later, can be suppressed, and a high etching rate can be achieved. Here, the atomic ratio of the transition metal and silicon of the transition metal silicide target is transition metal:silicon = 1:3 or more and 1:15 or less, which has a significant effect of suppressing the decrease in wet etching speed by the columnar structure, and the phase shift film (30) This is preferable because it can increase the cleaning resistance and also makes it easier to increase the transmittance.

The composition and thickness of the phase shift film 30 are adjusted so that the phase shift film 30 has the above-described phase difference and transmittance. The composition of the phase shift film 30 can be controlled by the content ratio of the elements constituting the sputter target (for example, the ratio of the transition metal content to the silicon content), the composition and flow rate of the sputter gas, etc. The thickness of the phase shift film 30 can be controlled by sputtering power, sputtering time, etc. Additionally, the phase shift film 30 is preferably formed using an in-line sputtering device. When the sputtering device is an in-line sputtering device, the thickness of the phase shift film 30 can be controlled also by the transfer speed of the substrate. In this way, control is performed so that the content of light elements including oxygen and nitrogen in the phase shift film 30 is 40 atomic% or more and 70 atomic% or less.

When the phase shift film 30 is made of a single film, the above-described film formation process is performed only once by appropriately adjusting the composition and flow rate of the sputter gas. When the phase shift film 30 is composed of a plurality of films with different compositions, the above-described film forming process is performed multiple times by appropriately adjusting the composition and flow rate of the sputter gas. The phase shift film 30 may be deposited using targets having different content ratios of elements constituting the sputter target. When performing the film forming process multiple times, the sputter power applied to the sputter target may be changed for each film forming 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. When it is made of a transition metal silicide material, the state of surface oxidation of the phase shift film 30 is adjusted to suppress penetration by the etchant due to the presence of the oxide of the transition metal on the surface of the phase shift film 30. You may 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, compared to the transition metal silicide material containing oxygen described above, the content of the oxide of the transition metal is small. Therefore, when the material of the phase shift film 30 is transition metal silicide nitride, the surface treatment step may or may not be performed.

Examples of the surface treatment process for adjusting the state of surface oxidation of the phase shift film 30 include surface treatment with an acidic aqueous solution, surface treatment with an alkaline aqueous solution, and surface treatment with dry treatment such as ashing. You can.

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

3. Etching mask film formation process

After the phase shift film formation process, surface treatment to adjust the surface oxidation state of the surface of the phase shift film 30 is performed as needed, and then the phase shift film 30 is formed by a sputtering method. An etching mask film 40 is formed on the. The etching mask film 40 is preferably formed using an in-line sputtering device. When the sputtering device is an in-line sputtering device, the thickness of the etching mask film 40 can be controlled also by the transfer speed of the transparent substrate 20.

The etching mask film 40 is formed 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. A sputter gas atmosphere consisting of an inert gas containing at least one type selected from the group consisting of gas, argon gas, 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 type of gas and an active gas containing at least one type selected from the group consisting of oxygen gas, nitrogen gas, nitrogen monoxide gas, nitrogen dioxide gas, carbon dioxide gas, hydrocarbon-based gas, and fluorine-based gas. Sputtering made of gas is performed in a gas atmosphere. Examples of hydrocarbon-based gas include methane gas, butane gas, propane gas, and styrene gas. Also, by adjusting the gas pressure in the film formation chamber when sputtering is performed, the etching mask film 40 can be made into a columnar structure like the phase shift film 30. As a result, side etching during pattern formation, which will be described later, can be suppressed, and a high etching rate can be achieved.

When the etching mask film 40 is made of a single film with a uniform composition, the above-described film forming process 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 with different compositions, the above-described film formation process is performed multiple times by changing the composition and flow rate of the sputter gas for each film formation process. When the etching mask film 40 is made 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 with the elapsed time of the film formation process.

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

Moreover, since the phase shift mask blank 10 shown in FIG. 1 is provided with the etching mask film 40 on the phase shift film 30, when manufacturing the phase shift mask blank 10, the etching mask film Perform the forming process. Additionally, when manufacturing a phase shift mask blank including 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 forming process, the etching mask is 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 a resist film on the phase shift film 30, a resist film is formed after the 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. Additionally, the phase shift mask blank 10 of Embodiment 2 has a phase shift film 30 formed thereon, 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 precision is obtained without a decrease in the transmittance of the transparent substrate due to damage to the substrate by the wet etching solution. Lose.

Additionally, when forming the phase shift film 30 on the transparent substrate 20, the gas pressure in the film formation chamber during sputtering may be formed at 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. By setting the indentation hardness of the phase shift film 30 to 18 GPa or more and 23 GPa or less, side etching during pattern formation, which will be described later, can be suppressed, and a high etching rate can be achieved, and the transparent substrate 20 Surface roughness can be suppressed. Here, as described above, the atomic ratio of the transition metal and silicon of the transition metal silicide target is transition metal:silicon = 1:3 or more and 1:15 or less to reduce the wet etching rate and to reduce the indentation hardness to 18 GPa or more and 23 GPa or less. This is preferable because the suppressing effect is large, the cleaning resistance of the phase shift film 30 can be increased, and the transmittance can be easily increased.

Embodiment 3. 4.

In Embodiments 3 and 4, a method for manufacturing a phase shift mask is explained.

Fig. 3 is a schematic diagram showing a method for manufacturing a phase shift mask according to Embodiment 3. Fig. 4 is a schematic diagram showing the manufacturing method of the 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 phase shift mask blank 10 is described below. ) A resist film pattern 50 is formed by forming a resist film on the resist film and drawing and developing a desired pattern on the resist film (first resist film pattern formation process), and the resist film pattern 50 is formed. A process 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 A step of forming a phase shift film pattern 30a on the transparent substrate 20 by wet etching the phase shift film 30 using (40a) as a mask (phase shift film pattern formation process) is included. And, it further includes a second resist film pattern forming process and a second etching mask film pattern forming process.

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 forms a resist film on the following phase shift mask blank 10. By performing the process and drawing and developing a desired pattern on the resist film, a resist film pattern 50 is formed (first resist film pattern formation process), and a phase shift film ( It includes a process of wet etching 30 and forming a phase shift film pattern 30a on the transparent substrate 20 (phase shift film pattern formation process).

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

Manufacturing process of phase shift mask according to Embodiment 3

1. First resist film pattern formation process

In the first resist film pattern formation process, a resist film is first formed on the etching mask film 40 of the phase shift mask blank 10 of Embodiment 1. The resist film material used is not particularly limited. For example, it may be sensitive to laser light having any wavelength selected from the wavelength range of 350 nm to 436 nm, which will be described later. Additionally, the resist film may be either positive or negative.

Thereafter, a desired pattern is drawn on the resist film using laser light having a wavelength selected from the wavelength range of 350 nm to 436 nm. The pattern drawn on the resist film is the pattern formed on the phase shift film 30. Patterns drawn on the resist film include line and space patterns and hole patterns.

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 pattern formation process

In the first etching mask pattern forming process, the etching mask film 40 is first etched using the first resist film pattern 50 as a mask, and the first etching mask film pattern 40a is formed. 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, it is preferable because the etching speed is fast and side etching can be suppressed. The etchant for etching the etching mask film 40 is not particularly limited as long as it can selectively etch the etching mask film 40. Specifically, an etching solution containing cerium ammonium nitrate and perchloric acid can be mentioned.

Thereafter, the first resist film pattern 50 is peeled off using a resist stripper or by ashing, as shown in FIG. 3(b). In some cases, the next phase shift film pattern formation process may be performed without peeling the first resist film pattern 50.

3. Phase shift film pattern formation process

In the first phase shift film pattern formation process, 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) is formed. Examples of the phase shift film pattern 30a include a line and space pattern and a hole pattern. 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 etching solution containing ammonium fluoride, phosphoric acid, and hydrogen peroxide, and an etching solution containing ammonium hydrogen fluoride and hydrogen peroxide.

Wet etching is performed for a time (over) longer than the time (just etching time) until the transparent substrate 20 is exposed in the phase shift film pattern 30a in order to improve the cross-sectional shape of the phase shift film pattern 30a. etching time) is preferable. Considering the influence on the transparent substrate 20, etc., the over-etching time is preferably within the just-etching time plus 20% of the just-etching time, and is 10% of the just-etching time. It is more desirable to do it within a longer period of 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 used is not particularly limited. For example, it may be sensitive to laser light having any wavelength selected from the wavelength range of 350 nm to 436 nm, which will be described later. Additionally, the resist film may be either positive or negative.

Thereafter, a desired pattern is drawn on the resist film using laser light having a wavelength selected from the wavelength range of 350 nm to 436 nm. The pattern drawn on the resist film is a light-shielding pattern that blocks light from the outer peripheral area of the area where the pattern is formed in the phase shift film 30, a light-shielding pattern that blocks light from the central part of the phase shift film pattern, etc. Additionally, the pattern drawn on the resist film may be a pattern without a light-shielding band pattern that blocks light from the central portion of the phase shift film pattern 30a, depending on the transmittance of the phase shift film 30 with respect to the 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 pattern formation process

In the second etching mask 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 is formed. A film pattern 40b is formed. The first etching mask film pattern 40a is formed of a chromium-based material containing chromium (Cr). The 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 etching solution containing ammonium cerium nitrate and perchloric acid can be mentioned.

Thereafter, the second resist film pattern 60 is peeled off using a resist stripper or by ashing.

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

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

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

Manufacturing process of phase shift mask according to Embodiment 4

1. Resist film pattern formation process

In the resist film pattern formation process, a resist film is first formed on the phase shift film 30 of the phase shift mask blank 10 of Embodiment 2. The resist film material used is the same as that described in Embodiment 3. In addition, before forming the resist film, if necessary, you may perform surface modification treatment on the phase shift film 30 in order to improve adhesion to the phase shift film 30. As described above, after forming a resist film, a desired pattern is drawn on the resist film using laser light having a wavelength selected from the wavelength range of 350 nm to 436 nm. Thereafter, 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 process, 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). The etchant and over-etching time for etching the phase shift film pattern 30a and the phase shift film 30 are the same as those described in Embodiment 3.

Thereafter, the resist film pattern 50 is peeled off using a resist stripper 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 is reduced. can be shortened, and a phase shift film pattern with a good cross-sectional shape can be formed. Therefore, a phase shift mask capable of transferring a high-precision phase shift film pattern with high precision can be manufactured. The phase shift mask manufactured in this way can respond to miniaturization of line and space patterns and contact holes. In addition, when manufacturing a phase shift mask using a phase shift mask blank having the phase shift film 30 whose indentation hardness derived by the nanoindentation method is 18 GPa or more and 23 GPa or less, in addition to the above-described effects, the transparent The surface roughness of the substrate 20 can be suppressed and the cleaning resistance of the phase shift film 30 can be improved.

Embodiment 5.

In Embodiment 5, a manufacturing method of a display device will be described. The display device uses a phase shift mask 100 manufactured using the above-described phase shift mask blank 10, or a phase shift mask 100 manufactured by the above-described manufacturing method of the phase shift mask 100. It is manufactured by performing a process 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 will be described 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 disposed to face the resist film formed on the display device substrate via the projection optical system of the exposure device.

2. Pattern transfer process

In the pattern transfer process, exposure light is irradiated to the phase shift mask 100, 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 a composite light including i-line, h-line, and g-line, or monochromatic light of i-line. When composite light is used as the exposure light, the intensity of the exposure light can be increased to increase throughput, and thus the manufacturing cost of the display device can be lowered.

According to the display device manufacturing method of this Embodiment 3, a high-precision display device with high resolution and fine line and space patterns and contact holes can be manufactured.

Furthermore, 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 pattern for transfer. Although the cases have been described, they are not limited to these. 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 blank and method of manufacturing the same

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

Thereafter, the synthetic quartz glass substrate was placed on a tray (not shown) with its main surface facing downward and loaded into the chamber of an in-line sputtering device.

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

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

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.

Transmittance and phase difference were measured on the surface of the phase shift film 30 (phase shift film 30) of the obtained phase shift mask blank 10 using MPM-100 manufactured by Lasertech. To measure the transmittance and phase difference of the phase shift film 30, a substrate (dummy substrate) with a phase shift film in which the phase shift film 30 is deposited on the main surface of a synthetic quartz glass substrate manufactured 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 a substrate (dummy substrate) equipped 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).

Additionally, the obtained phase shift mask blank 10 was subjected to compositional analysis in the depth direction by X-ray photoelectron spectroscopy (XPS).

In the depth direction composition analysis results of the phase shift mask blank 10 by Except for the composition gradient region at the interface between the shift film 30 and the etching mask film 40, the content of each constituent element in the depth direction is almost constant, with Mo being 8 at%, Si being 40 at%, and N This was 48 atomic%, and O was 4 atomic%. Additionally, 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. Additionally, the total content of light elements oxygen and nitrogen was 52 atomic%, within the range of 50 atomic% to 65 atomic%. In addition, the reason why oxygen is contained in the phase shift film 30 is thought to be that the sputtering gas pressure was high at 0.8 Pa or more and a trace amount of oxygen was present in the chamber at the time of film formation.

In addition, the indentation hardness of the obtained phase shift film 30 was measured (the measurement method will be described later), and the indentation hardness satisfied 18 GPa or more and 23 GPa or less.

Next, cross-sectional SEM (scanning electron microscopy) observation was performed at a magnification of 80,000 at the center position of the transfer pattern formation area of the obtained phase shift mask blank 10, and as a result, the phase shift film 30 had a columnar structure. It has been confirmed that it has. 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 toward the film thickness direction of the phase shift film 30. It was confirmed that the columnar particle structure of the phase shift film 30 was such that the columnar particles in the film thickness direction were formed irregularly, and the length of the columnar particles in the film thickness direction was also uneven. Additionally, it was confirmed that the small portion of the phase shift film 30 was formed continuously in the film thickness direction. In addition, with respect to the image obtained by this cross-sectional SEM observation, the area including the center of the thickness direction of the phase shift film 30 was extracted as image data of 64 pixels vertically and 256 pixels horizontally (Figure 5 (a) )). Additionally, 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) of the origin of the spatial frequency is 3136000, and that, separately from the maximum signal intensity, a spatial frequency spectrum with a signal intensity of 66150 exists. Confirmed. This gives 66150/3136000 = 0.021 (i.e. 2.1%) for the maximum signal intensity corresponding to the origin of the spatial frequency, and the phase shift film 30 had a columnar structure with a signal intensity of 1.0% or more.

In addition, for the Fourier transform image in FIG. 5(b), the origin of the spatial frequency, that is, the center of the image in FIG. 5(b), is set as the origin (0), and the maximum corresponding to both ends of the horizontal axis of 256 pixels is When the spatial frequency is set to 1 (100%), a signal with a signal intensity of 2.1% of the maximum signal intensity corresponding to the origin of the spatial frequency has a columnar structure with the signal at a position 0.055, that is, 5.5% away from the origin. It was a phase shift film 30 with . In addition, the same applies to the Fourier transform images of the following examples and comparative examples.

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

B. Phase shift mask and method of manufacturing the same

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. A photoresist film was applied.

Afterwards, a heating/cooling process was performed to form a photoresist film with a film thickness of 520 nm.

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

Thereafter, using the resist film pattern as a mask, the etching mask film was wet etched with a chromium etching solution containing cerium ammonium nitrate and perchloric acid to form the 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 using 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 at an over-etching time of 110% in order to verticalize the cross-sectional shape and to form the required fine pattern. The just etching time in Example 1 was 0.15 times the just etching time in the comparative example described later, and the etching time could be significantly shortened.

After that, the resist film pattern was peeled off.

After that, a photoresist film was applied using a resist coating device to cover the first etching mask film pattern 40a.

Afterwards, a heating/cooling process was performed to form a photoresist film with a film thickness of 520 nm.

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

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

Afterwards, the second resist film pattern 60 was peeled off.

In this way, on the transparent substrate 20, a layered structure of the phase shift film pattern 30a with a hole diameter of 1.5 μm, the phase shift film pattern 30a, and the etching mask film pattern 40b is formed in the transfer pattern formation area. A phase shift mask 100 with a light blocking zone formed was obtained.

The 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 composed of the top, bottom, and side surfaces of the phase shift film pattern. The angle of the cross section of the phase shift film pattern refers to the angle formed by the part where the upper surface and the side surface of the phase shift film pattern are in contact (upper side) and the part where the side surface and lower side are in contact (lower side). The cross-sectional angle of the phase shift film pattern 30a of the obtained phase shift mask was 74°, and it 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 believed that the fact that the phase shift film pattern 30a has a good cross-sectional shape by making the phase shift film 30 a columnar structure is due to the following mechanism. From the observation results 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 formed irregularly. In addition, from the observation results of the dark-field planar STEM photograph of FIG. 6 and the cross-sectional SEM photograph of FIG. 7, the phase shift film 30 has a particle portion of each column with a relatively high density and a particle portion with a relatively low density. It is formed of small parts. From these facts, when patterning the phase shift film 30 by wet etching, the etchant penetrates into small portions of the phase shift film 30, making it easy for etching to proceed in the film thickness direction, while the film thickness In the direction perpendicular to the direction (direction within the substrate surface), columnar particles are formed irregularly, and small portions in this direction are formed intermittently, so it is difficult for etching in this direction to proceed, and side etching is suppressed. , it is believed that the phase shift film pattern 30a has a good cross-sectional shape that is close to vertical. In addition, the phase shift film pattern was not observed to seep into either the interface with the etching mask film pattern or the interface with the substrate. Therefore, in exposure light containing light in the wavelength range of 300 nm to 500 nm, 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, it can be said that when the phase shift mask of Example 1 is set on the mask stage of an exposure device and exposed and transferred to a resist film on a display device, a fine pattern of less than 2.0 μm can be transferred with high precision.

In addition, the cross-sectional SEM photograph in FIG. 7 shows that, in the manufacturing process of the phase shift mask of Example 1, the phase shift film 30 was wet-etched with a molybdenum silicide etchant using the first etching mask film pattern 40a as a mask. This is a cross-sectional SEM photograph after etching (110% over-etching) to form 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 the surface roughness of the transparent substrate 20 was negligible.

Example 2.

A. Phase shift mask blank and method of manufacturing the same

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

By the same method as Example 1, a synthetic quartz glass substrate was brought into the chamber of an in-line sputtering device. As the first sputter target, second sputter target, third sputter target, and fourth sputter target, the same sputter target material as Example 1 was used. And, with the sputtering gas pressure in the first chamber set to 1.6 Pa, an inert gas consisting of argon (Ar) gas, helium (He) gas, and nitrogen (N ₂ ) gas, and nitrogen monoxide gas (NO), which is a reactive gas, are used. ) mixed gas (Ar: 18 sccm, N ₂ : 15 sccm, He: 50 sccm, NO: 4 sccm) was introduced. Then, a sputter power of 7.6 kW is applied to the first sputter target containing molybdenum and silicon (molybdenum:silicon = 1:9), and molybdenum and silicon are deposited on the main surface of the transparent substrate 20 by reactive sputtering. Oxidized nitrides of molybdenum silicide containing oxygen and nitrogen were deposited. Then, a phase shift film 30 with a film thickness of 140 nm was formed.

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

After that, the 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.

Transmittance and phase difference were measured for the phase shift film of the obtained phase shift mask blank 10 (a phase shift film whose surface was cleaned with pure water) using MPM-100 manufactured by Lasertech. To measure the 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 deposited on the main surface of a synthetic quartz glass substrate manufactured 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 a substrate (dummy substrate) equipped 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).

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

As a result, like 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, with Mo being 7 atom%, Si being 38 atom%, N being 45 atom%, and O being 10 atom%. Additionally, the atomic ratio of molybdenum to silicon was 1:5.4 and was within the range of 1:3 or more and 1:15 or less. Additionally, the total content of light elements oxygen, nitrogen, and carbon was 55 atomic%, within the range of 50 atomic% to 65 atomic%.

Next, as a result of cross-sectional SEM observation at a magnification of 80000 at the center of the transfer pattern formation area of the obtained phase shift mask blank 10, it was confirmed that the phase shift film 30 has 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 toward the film thickness direction of the phase shift film 30. It was confirmed that the columnar particle structure of the phase shift film 30 was such that the columnar particles in the film thickness direction were formed irregularly, and the length of the columnar particles in the film thickness direction was also uneven. Additionally, it was confirmed that the small portion of the phase shift film 30 was formed continuously in the film thickness direction. In addition, with respect to the image obtained by this cross-sectional SEM observation, the area including the center of the thickness direction of the phase shift film 30 was extracted as image data of 64 pixels vertically and 256 pixels horizontally (Figure 8 (a) )). Additionally, Fourier transform was performed on the image data shown in Figure 8(a) (Figure 8(b)). In the spatial frequency spectrum distribution obtained by Fourier transform, the signal intensity (maximum signal intensity) of the origin of the spatial frequency is 2406000, and that, separately from the maximum signal intensity, a spatial frequency spectrum with a signal intensity of 39240 exists. Confirmed. This results in 39240/2406000 = 0.016 (i.e. 1.6%) for the maximum signal intensity corresponding to the origin of the spatial frequency, and the phase shift film 30 had a columnar structure with a signal intensity of 1.0% or more.

Additionally, for the Fourier transform image in Figure 8(b), the origin of the spatial frequency, that is, the center of the image in Figure 8(b), is set as the origin (0), and both ends of the 256 pixels on the horizontal axis are set as 1 (100%). ), a signal with a signal intensity of 1.6% of the maximum signal intensity corresponding to the origin of the spatial frequency is a phase shift film ( 30).

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

B. Phase shift mask and method of manufacturing the same

Using the phase shift mask blank manufactured as described above, a phase shift mask having a phase shift film pattern with a hole diameter of 1.5 μm was manufactured by the same method as Example 1. Wet etching of the phase shift film 30 was performed at an over-etching time of 110% in order to verticalize the cross-sectional shape and to form a fine pattern required. The just etching time in Example 2 was 0.07 times the just etching time in the comparative example described later, and the etching time could be significantly shortened.

The cross section of the obtained phase shift mask was observed with a scanning electron microscope. The cross-sectional angle of the phase shift film pattern 30a of the phase shift mask was 74° and had a cross-sectional shape close to vertical. In addition, the phase shift film pattern was not observed to seep into either the interface with the etching mask film pattern or the interface with the substrate. Therefore, in exposure light containing light in the wavelength range of 300 nm to 500 nm, 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, it can be said that when the phase shift mask of Example 2 is set on the mask stage of an exposure device and exposed and transferred to a resist film on a display device, a fine pattern of less than 2.0 μm can be transferred with high precision.

In addition, the cross-sectional SEM photograph in FIG. 9 shows that in the manufacturing process of the phase shift mask of Example 2, the phase shift film 30 was wet-etched with a molybdenum silicide etchant using the first etching mask film pattern 40a as a mask. This is a cross-sectional SEM photograph after etching (110% over-etching) to form 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 the surface roughness of the transparent substrate 20 was negligible.

Example 3.

A. Phase shift mask blank and method of manufacturing the same

The phase shift mask blank of Example 3 is a phase shift mask blank without the etching mask film in the phase shift mask blank of Example 1.

To manufacture the phase shift mask blank of Example 3, as in Example 1, a synthetic quartz glass substrate of size 1214 (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, first, with the sputtering gas pressure in the first chamber set to 1.4 Pa, 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 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.

With respect to the phase shift film of the obtained phase shift mask blank 10, the transmittance and phase difference were measured using MPM-100 manufactured by Lasertech. To measure the 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 deposited on the main surface of a synthetic quartz glass substrate manufactured by setting it 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).

The phase shift film 30 of the obtained phase shift mask blank 10 was subjected to composition analysis in the depth direction by , toward the depth direction, the content rate of each constituent element was almost constant. Additionally, 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. Additionally, the total content of light elements oxygen, nitrogen, and carbon was 52 atomic%, within the range of 50 atomic% to 65 atomic%. Additionally, the oxygen content was 0.3 atomic% and was in the range of more than 0 atomic% to 40 atomic% or less.

Next, cross-sectional SEM observation was performed at a magnification of 80000 at the center position of the transfer pattern formation area of the obtained phase shift mask blank 10, and as a result, it was confirmed that the phase shift film 30 had a columnar structure. It has been done. 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 toward the film thickness direction of the phase shift film 30. It was confirmed that the columnar particle structure of the phase shift film 30 was such that the columnar particles in the film thickness direction were formed irregularly, and the length of the columnar particles in the film thickness direction was also uneven. Additionally, it was confirmed that the small portion of the phase shift film 30 was formed continuously in the film thickness direction. In addition, with respect to the image obtained by this cross-sectional SEM observation, the area including the center of the thickness direction of the phase shift film 30 was extracted as image data of 64 pixels vertically and 256 pixels horizontally (Figure 10 (a) )). Additionally, Fourier transform was performed on the image data shown in Figure 10(a) (Figure 10(b)). In the spatial frequency spectrum distribution obtained by Fourier transform, the signal intensity (maximum signal intensity) of the origin of the spatial frequency is 31590000, and that, separately from the maximum signal intensity, a spatial frequency spectrum with a signal intensity of 47230 exists. Confirmed. This gives 47230/3159000 = 0.015 (i.e. 1.5%) for the maximum signal intensity corresponding to the origin of the spatial frequency, and the phase shift film 30 had a columnar structure with a signal intensity of 1.0% or more.

Additionally, for the Fourier transform image in FIG. 10(b), the origin of the spatial frequency, that is, the center of the image in FIG. 10(b), is set as the origin (0), and both ends of the 256 pixels on the horizontal axis are set to 1 (100%). ), a signal with a signal intensity of 1.5% of the maximum signal intensity 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 a phase shift film (30) with

Additionally, as in Example 1, dark-field planar STEM observation was performed near the center of the film thickness of the phase shift film 30. As a result, it was confirmed that, as in Example 1, each columnar particle and a small portion were formed in the phase shift film 30.

B. Phase shift mask and method of manufacturing the same

Using the phase shift mask blank 10 manufactured as described above, a phase shift mask having a phase shift film pattern with a hole diameter of 1.5 μm was manufactured by the same method as Example 1. Wet etching of the phase shift film 30 was performed with an over-etching time of 110% in order to verticalize the cross-sectional shape and to form a fine pattern required. The just etching time in Example 3 was 0.20 times the just etching time in the comparative example described later, and the etching time could be significantly shortened.

The cross section of the obtained phase shift mask was observed with a scanning electron microscope. The cross-sectional angle 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, the phase shift film pattern was not observed to seep into either the interface with the etching mask film pattern or the interface with the substrate. Therefore, in exposure light containing light in the wavelength range of 300 nm to 500 nm, 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, it can be said that when the phase shift mask of Example 3 is set on the mask stage of an exposure device and exposed and transferred to a resist film on a display device, a fine pattern of less than 2.0 μm can be transferred with high precision.

In addition, the cross-sectional SEM photograph in FIG. 11 shows that, in the manufacturing process of the phase shift mask of Example 3, the phase shift film 30 was wet-etched with a molybdenum silicide etchant using the first etching mask film pattern 40a as a mask. This is a cross-sectional SEM photograph after etching (110% over-etching) to form 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 negligible. Line edge roughness was better compared to Example 1.

In addition, in the above-described embodiment, the case where molybdenum was used as the transition metal was explained, but the same effect as described above can be obtained even in the case of other transition metals.

In addition, in the above-described embodiments, examples of a phase shift mask blank for display device manufacturing and a phase shift mask for display device manufacturing have been described, but the present invention is not limited to this. The phase shift mask blank or phase shift mask of the present invention can also be applied to semiconductor device manufacturing, MEMS manufacturing, printed circuit boards, etc. Additionally, 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, an example in which the size of the transparent substrate is 1214 size (1220 mm x 1400 mm x 13 mm) has been described, but it is not limited to this. In the case of a phase shift mask blank for display device manufacturing, a large-sized transparent substrate is used, and the size of the transparent substrate is 300 mm or more on one side. The size of the transparent substrate used for the phase shift mask blank for display device manufacture is, for example, 330 mm x 450 mm or more and 2280 mm x 3130 mm or less.

Additionally, in the case of phase shift mask blanks for semiconductor device manufacturing, MEMS manufacturing, and printed circuit boards, small-sized 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 for the above purpose is, for example, 63.1 mm x 63.1 mm or more and 228.6 mm x 228.6 mm or less. Usually, for semiconductor manufacturing and MEMS manufacturing, size 6025 (152 mm 228.6 mm × 228.6 mm) is used.

Comparative Example 1.

A. Phase shift mask blank and method of manufacturing the same

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

By the same method as Example 1, a synthetic quartz glass substrate was brought into the chamber of an in-line 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 sputter power of 7.6 kW is applied to the first sputter target containing molybdenum and silicon (molybdenum:silicon = 1:9), and molybdenum, silicon, and nitrogen are deposited on the main surface of the transparent substrate by reactive sputtering. nitride of molybdenum silicide was deposited. In this way, a phase shift film with 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.

After that, an etching mask film was formed by the same method as 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 and phase difference were measured using MPM-100 manufactured by Lasertec. To measure the transmittance and phase difference of the phase shift film, a substrate with a phase shift film (dummy substrate) in which the phase shift film was deposited on the main surface of a synthetic quartz glass substrate manufactured by setting it 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) provided 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).

Additionally, the obtained phase shift mask blank was subjected to compositional analysis in the depth direction using X-ray photoelectron spectroscopy (XPS). 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 in the depth direction was almost constant, with Mo being 8 atom%, Si being 39 atom%, N being 52 atom%, and O being 1 atom%. Additionally, the atomic ratio of molybdenum to silicon was 1:4.9 and was within the range of 1:3 or more and 1:15 or less. Additionally, the total content of light elements oxygen, nitrogen, and carbon was 53 atomic%, and was within the range of 50 atomic% to 65 atomic%.

Next, cross-sectional SEM observation was performed at a magnification of 80,000 at the central position of the transfer pattern formation area of the obtained phase shift mask blank 10. As a result, no columnar structure was confirmed in the phase shift film, and ultrafine It was confirmed that it was a crystal structure or amorphous structure. For the image obtained by this cross-sectional SEM observation, the area including the center of the thickness direction of the phase shift film 30 was extracted as image data of 64 pixels vertically and 256 pixels horizontally (FIG. 12(a)). . Additionally, 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) of the origin of the spatial frequency is 2073000, no strong signal separate from the maximum intensity signal is confirmed, and a space with a signal intensity of 12600 There was just a frequency spectrum. This results in 12600/2073000 = 0.006 (i.e. 0.6%) for the maximum signal intensity corresponding to the origin of the spatial frequency, and the phase shift film 30 has an ultrafine crystal structure that does not have a signal intensity of 1.0% or more. It was an amorphous structure.

B. Phase shift mask and method of manufacturing the same

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

In addition, the cross-sectional SEM photograph in FIG. 13 shows that, in the manufacturing process of the phase shift mask of the comparative example, the phase shift film 30 is wet-etched with a molybdenum silicide etchant using the first etching mask film pattern 40a as a mask. This is a cross-sectional SEM photograph before over-etching (110%), forming the phase shift film pattern 30a, and peeling off the 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 white cloudy state even when seen with the naked eye. Therefore, 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 an exposure device and exposed and transferred to a resist film on a display device, it is expected that it will be impossible to transfer a fine pattern of less than 2.0 μm.

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

A. Phase shift mask blank and method of manufacturing the same

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, as a transparent substrate 20, a synthetic quartz glass substrate of size 1214 (1220 mm x 1400 mm) was prepared. did.

Thereafter, in each case, the synthetic quartz glass substrate was placed on a tray (not shown) with its main surface facing downward and loaded into the chamber of the in-line sputtering apparatus.

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 is added. 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 the range where the phase shift film satisfies the predetermined transmittance and phase difference, Different values were used in each example (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 to 2.4 Pa, and the sputtering gas pressure in the other Comparative Examples 1 and 2 was 0.7. It did not satisfy the range of more than Pa and less than 2.4 Pa. Then, in each example, a sputter power of 7.6 kW is applied to the first sputter target containing molybdenum and silicon (molybdenum:silicon = 1:9), and a sputtering power of 7.6 kW is applied to the main surface of the transparent substrate 20 by reactive sputtering. A nitride of molybdenum silicide containing molybdenum, silicon, and nitrogen was deposited to form a phase shift film 30. In each example, the film thickness of the phase shift film 30 was 144 nm to 170 nm.

Next, in each example, the transparent substrate 20 provided with the phase shift film 30 is introduced 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 sputter 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 at 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, with the fourth chamber at a predetermined vacuum level, a mixture of argon (Ar) gas and methane (CH ₄ : 5.5%) gas, nitrogen (N ₂ ) gas, and oxygen (O ₂ ) gas are mixed. Gas was introduced, a sputter power of 2.0 kW was applied to the fourth sputter target made of chromium, and chromium carbide 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 stacked 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 example, the transmittance and phase difference were measured on the surface of the phase shift film 30 (phase shift film 30) of the obtained phase shift mask blank 10 using MPM-100 manufactured by Lasertec. To measure the transmittance and phase difference of the phase shift film 30, a substrate (dummy substrate) with a phase shift film in which the phase shift film 30 is deposited on the main surface of a synthetic quartz glass substrate manufactured by setting it on the same tray. was used. In each example, the transmittance and phase difference of the phase shift film 30 were measured by taking out a substrate (dummy substrate) provided with the phase shift film from the chamber before forming the etching mask film 40. As a result, in each case, the transmittance and phase difference both satisfied the required range (transmittance: 10 to 50% at a wavelength of 405 nm, phase difference: 160° to 200° at a wavelength of 405 nm).

In addition, in each case, composition analysis in the depth direction was performed on the obtained phase shift mask blank 10 by X-ray photoelectron spectroscopy (XPS).

In each example, in the depth direction composition analysis results 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 inclined region and the compositional inclined region at the interface between the phase shift film 30 and the etching mask film 40, the content of each constituent element was substantially constant in the depth direction. Additionally, in each case, the atomic ratios of molybdenum and silicon were all 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 6 × 6 matrix positions (36 positions) with a pitch of 50 um at measurement positions, and a special probe equipped with a diamond indenter is installed at each position at a maximum of 0.5 µm. By pressing in mN, the change in load was measured. From the measured values obtained at each position, outliers, maximum values, and minimum values were removed, and the indentation hardness in each example was calculated (see Table 1). Additionally, by removing outliers, maximum values, and minimum values, it was confirmed that the standard deviation of the measured values became 7% or less of the measured values.

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 did not satisfy 18 GPa or more and 23 GPa or less. It was.

B. Phase shift mask and method of manufacturing the same

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.

Afterwards, a heating/cooling process was performed to form a photoresist film with a film thickness of 520 nm.

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

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

Thereafter, in each example, using the first etching mask film pattern 40a as a mask, the phase shift film 30 is wet-etched using a molybdenum silicide etchant obtained by diluting a mixed solution of ammonium bifluoride and hydrogen peroxide with pure water. , a 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 verticalize the cross-sectional shape and to form the required fine pattern.

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

After that, the resist film pattern was peeled off.

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

Afterwards, a heating/cooling process was performed to form a photoresist film with a film thickness of 520 nm.

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

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

Afterwards, the second resist film pattern 60 was peeled off.

In addition, in each case, washing treatment using chemical solutions (sulfuric acid solution (SPM), ammonia solution (SC1), ozone water) was appropriately performed.

In this way, in each example, on the transparent substrate 20, a phase shift film pattern 30a with a hole diameter of 1.5 μm, a phase shift film pattern 30a, and an etching mask film pattern ( A phase shift mask 100 with a light blocking zone formed in the layered structure of 40b) was obtained.

Table 1 shows the sputtering gas pressure (Pa) at the time of forming the phase shift film 30 and the etching rate (nm/nm) of the phase shift film 30 in other Examples 1 to 4 and other Comparative Examples 1 and 2. minutes), the indentation hardness (GPa) of the phase shift film 30, the presence or absence of surface roughness of the transparent substrate 20 due to wet etching, and the cleaning resistance of the phase shift film 30 are shown, respectively.

14 shows the relationship between the etching rate, sputtering gas pressure, and indentation hardness in the phase shift film 30 of the phase shift mask 100 of other Examples 1 to 4 and other Comparative Examples 1 and 2. This is a graph representing . In Figure 14, from left to right (in descending order of etching rate), Comparative Example 1, Example 4, Example 3, Example 2, Example 1, and Comparative Example 2. It shows the indentation hardness and sputtering gas pressure. As shown in FIG. 14, it was found that there was a correlation between the etching rate in the phase shift film 30 and the indentation hardness or sputtering gas pressure.

The 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 composed of the top, bottom, and side surfaces of the phase shift film pattern. The angle of the cross section of the phase shift film pattern refers to the angle formed by the part where the upper surface and the side surface of the phase shift film pattern are in contact (upper side) and the part where the side surface and the lower side are in contact (lower side). As a result, the cross-sectional shape of the phase shift film pattern 30a of the phase shift masks of Examples 1 to 4 and Comparative Example 2 is in the range of 65° to 75°, and all have cross-sections that can sufficiently exhibit the phase shift effect. It had a shape. In other Examples 1 to 4, the surface of the transparent substrate 20 exposed by the phase shift mask 100 was smooth, and the decrease in transmittance due to the surface roughness of the transparent substrate 20 was negligible. Therefore, in exposure light containing light in the wavelength range of 300 nm to 500 nm, 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 other Examples 1 to 4 is 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. .

Additionally, a columnar structure was observed in all of the phase shift film patterns 30a of the phase shift mask 100 in other Examples 1 to 4.

In contrast, the surface of the exposed transparent substrate 20 of the phase shift mask 100 in Comparative Example 1 was rough and was in a white cloudy state even when seen with the naked eye. Therefore, 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 an exposure device and exposed and transferred to a resist film on a display device, it is expected that it will be impossible to transfer a fine pattern of less than 2.0 μm. .

In addition, in another comparative example 2, the surface of the transparent substrate 20 exposed by the phase shift mask 100 was smooth, and the decrease in transmittance due to surface roughness of the transparent substrate 20 was negligible. However, the amount of change in transmittance and phase difference due to the chemical solutions (sulfuric acid peroxide (SPM), ammonia peroxide (SC1), and ozone water) used in cleaning the phase shift mask 100 are large, so the amount of change required for the phase shift mask 100 is large. It was determined that transmittance and phase difference were not satisfied.

For this reason, when the phase shift mask of Comparative Example 2 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 will be impossible to transfer a fine pattern of less than 2.0 μm.

Additionally, the columnar structure was not observed in the phase shift film pattern 30a of the phase shift mask 100 in another comparative example 1. The same was true for the phase shift film pattern 30a of the phase shift mask 100 in 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 pattern
40b: second etching mask pattern
50: first resist film pattern
60: Second resist film pattern
100: Phase shift mask

Claims (13)

A photomask blank having a thin film for pattern formation on a transparent substrate,
The thin film for pattern formation contains a transition metal and silicon,
The thin film for pattern formation has a columnar structure,
The columnar structure of the thin film for pattern formation is an area including the center in the thickness direction of the thin film for pattern formation, from an image obtained by observing a cross section of the photomask blank by scanning electron microscopy at a magnification of 80,000 times, and is 64 pixels vertically. In the image of the spatial frequency spectrum distribution obtained by extracting image data of 256 pixels horizontally and performing Fourier transformation on the image data, the center of the image of the spatial frequency spectrum distribution is set as the origin of the spatial frequency, and the spatial frequency spectrum A photomask blank characterized in that a spatial frequency spectrum having a signal intensity of 1.0% or more exists with respect to the signal intensity corresponding to the origin of the spatial frequency, which is the maximum signal intensity in the image of the distribution. According to paragraph 1,
The columnar structure of the pattern forming thin film is set on the image data, with the origin set at 0% and the horizontal axis set at 100% with the maximum spatial frequency corresponding to both ends of the 256-pixel horizontal direction of the image data. A photomask blank, characterized in that a signal having a signal intensity of 1.0% or more exists at a position on the horizontal axis that is 2.0% or more away from the origin of the spatial frequency. According to paragraph 1,
A photomask blank, characterized in that the atomic ratio of the transition metal and the silicon included in the pattern forming thin film is transition metal:silicon = 1:3 or more and 1:15 or less. According to paragraph 1,
A photomask blank characterized in that the columnar structure of the thin film for pattern formation includes columnar particles extending in the film thickness direction formed over the surface of the transparent substrate. According to paragraph 4,
A photomask blank, wherein the columnar particles are irregularly formed in a direction perpendicular to the film thickness direction of the pattern forming thin film. According to paragraph 1,
A photomask blank, characterized in that the thin film for pattern formation further contains at least nitrogen or oxygen. According to paragraph 1,
A photomask blank, characterized in that the transition metal is molybdenum. According to paragraph 1,
A photomask blank, characterized in that the thin film for pattern formation is a phase shift film having optical properties of a transmittance of 1% to 80% and a phase difference of 160° to 200° for a representative wavelength of exposure light. According to paragraph 1,
A photomask blank comprising an etching mask film having different etching selectivity with respect to the pattern forming thin film on the pattern forming thin film. According to clause 9,
A photomask blank, characterized in that the etching mask film is made of a material that contains chromium and does not contain silicon. A process of preparing the photomask blank according to claim 1,
Forming a resist film on the pattern forming thin film, wet etching the pattern forming thin film using the resist film pattern formed from the resist film as a mask, and forming a transfer pattern on the transparent substrate. A method of manufacturing a photomask. A process of preparing the photomask blank according to claim 9,
forming a resist film on the etching mask film, wet etching the etching mask film using a resist film pattern formed from the resist film as a mask, and forming an etching mask film pattern on the pattern forming thin film;
A method of manufacturing a photomask, comprising the steps of using the etching mask film pattern as a mask, wet etching the pattern forming thin film, and forming a transfer pattern on the transparent substrate. A photomask obtained by the photomask manufacturing method according to claim 11 or 12 is placed 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 of manufacturing a display device, comprising an exposure process.

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