KR20220135170A - Photomask blank, method for manufacturing photomask, and method for manufacturing display device - Google Patents

Abstract

The present invention relates to a photomask blank, which shortens the etching time when wet-etching a fine pattern (thin film pattern for pattern formation) on a thin film for pattern formation, has high light resistance and chemical resistance, and forms a fine pattern having a cross-sectional shape of a near-vertical edge and a good LER. In the photomask blank for manufacturing a display device having a thin film for pattern formation on a transparent substrate, the thin film for pattern formation is made of a material containing titanium (Ti), silicon (Si), and nitrogen (N) and has a columnar structure, wherein the content of oxygen contained in the pattern formation is 7 atomic % or less. The present invention relates to a photomask blank for manufacturing a display device, a method for manufacturing a photomask for manufacturing a display device, and a method for manufacturing a display device.

Description

PHOTOMASK BLANK, METHOD FOR MANUFACTURING PHOTOMASK, AND METHOD FOR MANUFACTURING DISPLAY DEVICE

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

DESCRIPTION OF RELATED ART In recent years, display apparatuses, such as an FPD (Flat Panel Display) which are representative of LCD (Liquid Crystal Display), high-definition and high-speed display are progressing rapidly along with the enlargement of a screen and a wide viewing angle. One of the elements necessary for this high-definition and high-speed display is to produce an electronic circuit pattern such as an element and wiring with a fine and high dimensional accuracy. Photolithography is often used for patterning this electronic circuit for a display device. For this reason, the photomask like a phase shift mask for display apparatus manufacture in which a fine and high-precision pattern was formed and a binary mask is needed.

For example, Patent Document 1 describes a photomask for exposing a fine pattern. In Patent Document 1, a mask pattern formed on a transparent substrate of a photomask is composed of a light-transmitting portion that transmits light with an intensity that substantially contributes to exposure, and a light-semi-transmissive portion that transmits light with an intensity that does not substantially contribute to exposure. composition is described. Moreover, patent document 1 describes improving the contrast of a boundary part by making the light which passed through the boundary part vicinity of the said light semitransmissive part and a light transmissive part cancel each other using a phase shift effect. Further, in Patent Document 1, in the photomask, the light-semitransmissive portion is composed of a thin film composed of a material mainly composed of nitrogen, metal and silicon, and silicon, which is a component of the material constituting the thin film, is 34 It is described that it contains from 60 atomic% to 60 atomic%.

Patent Document 2 describes a halftone phase shift mask blank used for lithography. It is described in patent document 2 that a mask blank is equipped with the phase shift layer deposited on the board|substrate, the etch stop layer deposited on the said board|substrate, and the said etch stop layer. Further, Patent Document 2 describes that a photomask having a phase shift of approximately 180° at a selected wavelength of less than 500 nm and a light transmittance of at least 0.001% can be manufactured using this mask blank.

Patent Document 3 describes a photomask blank having a thin film for pattern formation on a transparent substrate. Patent Document 3 describes that the photomask blank is an original plate for forming a photomask having a transfer pattern on a transparent substrate by wet etching the thin film for pattern formation. Moreover, it is described in patent document 3 that the thin film for pattern formation of a photomask blank contains a transition metal and a silicon, and has a columnar structure.

Japanese Patent Publication No. 2966369 Japanese Patent Laid-Open No. 2005-522740 Japanese Patent Laid-Open No. 2020-95248

In recent years, as a photomask used for manufacturing high-precision (1000 ppi or more) panels, it is a photomask to enable high-resolution pattern transfer, and for forming fine patterns of 6 µm or less in hole diameter and 4 µm or less in line width There is a demand for a photomask in which a transfer pattern including a thin film pattern is formed. Specifically, there is a demand for a photomask in which a transfer pattern including a fine pattern having a diameter or width of 1.5 μm is formed.

In addition, in order to realize higher-resolution pattern transfer, a photomask blank (phase shift photomask blank) having a thin film for pattern formation (phase shift film) having a transmittance of 20% or more with respect to exposure light, and transmittance with respect to exposure light The photomask (phase shift mask) in which the thin film pattern (phase shift film pattern) for pattern formation 20 % or more was formed is calculated|required. In addition, since the photomask obtained by patterning the thin film for pattern formation of the photomask blank is repeatedly used for pattern transfer to the object to be transferred, it is also desired to have high light resistance to ultraviolet rays (ultraviolet light resistance) assuming actual pattern transfer. do. Moreover, since a photomask blank and a photomask are repeatedly washed at the time of their manufacture and use, it is also desired that washing|cleaning tolerance (chemical resistance) is high.

The atomic ratio of metal and silicon in the metal silicide compound (metal silicide-based material) constituting the thin film for pattern formation in order to satisfy the requirements for transmittance to exposure light, UV light resistance (hereinafter simply light resistance) and chemical resistance. It is considered as one of the effective methods to make the ratio of silicon in a high. However, in the case of a metal silicide compound thin film having a high silicon ratio, the wet etching rate is significantly slow (wet etching time is long). Therefore, while the etching selectivity between the thin film for pattern formation of the metal silicide compound thin film and the transparent substrate decreases, damage to the transparent substrate by the wet etching solution occurs, and there are problems such as a decrease in transmittance of the transparent substrate. . Therefore, it is desired to secure a sufficient etching selectivity with the transparent substrate by increasing the wet etching rate of the thin film for pattern formation, and to reduce or suppress damage to the transparent substrate. However, it is not easy to satisfy high chemical resistance and light resistance while increasing the etching rate.

In the binary photomask blank provided with a light-shielding film containing a transition metal and silicon, even when a light-shielding pattern is formed on the light-shielding film by wet etching, there are demands for light resistance and chemical resistance.

Moreover, in order to perform pattern transfer with high precision, it is preferable that the cross-sectional shape of the edge of the fine pattern (thin film pattern for pattern formation) formed in the thin film for pattern formation of a photomask is a shape close|similar to a perpendicular|vertical shape. By using a photomask in which the cross-sectional shape of the fine pattern is close to vertical, it becomes possible to perform high-resolution pattern transfer.

In addition, the line edge roughness (LER) of the fine pattern of the photomask is an important index. LER is an index indicating the size of the unevenness of the shape formed by the edge of the fine pattern when the fine pattern of the photomask is viewed from the top. In order to enable high-resolution pattern transfer, it is preferable that the LER of the photomask is good. However, it is not easy to obtain a thin film for pattern formation that satisfies all characteristics such as high etching rate, high light resistance and chemical resistance, good edge cross-sectional shape, and good LER.

The present invention has been made to solve the above-mentioned problems. That is, the present invention can shorten the etching time when wet etching a fine pattern (thin film pattern for pattern formation) on a thin film for pattern formation, has high light resistance and chemical resistance, and has a cross-sectional shape of an edge close to vertical and An object of the present invention is to provide a photomask blank for manufacturing a display device capable of forming a fine pattern having a good LER.

In addition, the present invention provides a method for manufacturing a photomask for manufacturing a display device having a fine pattern (a thin film pattern for pattern formation) having a cross-sectional shape of a near-vertical edge and a good LER while having high light resistance and tolerance, and a display device An object of the present invention is to provide a manufacturing method of

In order to solve the said subject, this invention has the following structures.

(Configuration 1)

Configuration 1 of the present invention is a photomask blank for manufacturing a display device having a thin film for pattern formation on a transparent substrate,

The thin film for pattern formation is made of a material containing titanium (Ti), silicon (Si), and nitrogen (N),

The thin film for pattern formation has a columnar structure,

A photomask blank for manufacturing a display device, characterized in that the oxygen content contained in the pattern forming thin film is 7 atomic% or less.

(Configuration 2)

In configuration 2 of the present invention, the thin film for pattern formation includes a central portion in the thickness direction of the thin film for pattern formation with respect to an image obtained by scanning electron microscope observation of a cross section of the photomask blank at a magnification of 80000 times. In the spatial frequency spectrum distribution obtained by extracting the image data of 64 pixels in length x 256 pixels in width and Fourier transforming the image data for the region to It is the photomask blank for display device manufacture of the structure 1 characterized by the presence of the spatial frequency spectrum with intensity|strength.

(Configuration 3)

Configuration 3 of the present invention is characterized in that the thin film for pattern formation is at a spatial frequency that is 6.7% or more away from the origin of the spatial frequency when a signal having a signal strength of 0.8% or more has a maximum spatial frequency of 100%. It is a photomask blank for display device manufacture of the structure 1 or 2.

(Configuration 4)

Structure 4 of this invention is a phase shift film provided with the optical characteristic that the transmittance|permeability is 1 % or more and 80 % or less, and the phase difference of 160 degrees or more and 200 degrees or less with respect to the representative wavelength of exposure light with respect to the representative wavelength of the said pattern formation said pattern formation It is a photomask blank for display device manufacture in any one of the structures 1 to 3 made into.

(Configuration 5)

Configuration 5 of the present invention is a photomask blank for manufacturing a display device according to any one of Configurations 1 to 4, wherein an etching mask film having different etching selectivity with respect to the thin film for pattern formation is provided on the thin film for pattern formation.

(Configuration 6)

Configuration 6 of the present invention is a photomask blank for manufacturing a display device according to Configuration 5, wherein the etching mask film is made of a material containing chromium and substantially not containing silicon.

(Configuration 7)

Configuration 7 of the present invention comprises the steps of preparing a photomask blank for manufacturing a display device according to any one of Configurations 1 to 4;

forming a resist film on the thin film for pattern formation, and wet etching the thin film for pattern formation using the resist film pattern formed with the resist film as a mask to form a transfer pattern on the transparent substrate; A method of manufacturing a photomask for manufacturing a display device, characterized in that

(Configuration 8)

Configuration 8 of the present invention comprises the steps of preparing a photomask blank for manufacturing a display device of configuration 5 or 6;

forming a resist film on the etching mask film, wet etching the etching mask film using the resist film pattern formed with the resist film as a mask to form an etching mask film pattern on the pattern forming thin film;

A method of manufacturing a photomask for manufacturing a display device, comprising a step of forming a transfer pattern on the transparent substrate by wet-etching the pattern-forming thin film using the etching mask film pattern as a mask.

(Configuration 9)

In configuration 9 of the present invention, the display device manufacturing photomask obtained by the method for manufacturing the display device manufacturing photomask of the configuration 7 or 8 is mounted on a mask stage of an exposure apparatus, and the transfer is formed on the display device manufacturing photomask. A method for manufacturing a display device comprising an exposure step of exposing and transferring a pattern to a resist formed on a substrate for a display device.

According to the present invention, it is possible to shorten the etching time at the time of wet etching a fine pattern (thin film pattern for pattern formation) on a thin film for pattern formation, and to have high light resistance and chemical resistance and anisotropic wet etching characteristics. It is possible to provide a photomask blank for manufacturing a display device capable of forming a fine pattern having a cross-sectional shape of a near-vertical edge and a good LER.

In addition, according to the present invention, a method of manufacturing a photomask for manufacturing a display device having a fine pattern having a cross-sectional shape of a near-vertical edge and a good LER by having high light resistance and chemical resistance, and anisotropic wet etching properties; and a method of manufacturing a display device.

BRIEF DESCRIPTION OF THE DRAWINGS It is a cross-sectional schematic diagram which shows the film|membrane structure of the photomask blank of embodiment of this invention.
It is a cross-sectional schematic diagram which shows the other film|membrane structure of the photomask blank of embodiment of this invention.
It is a cross-sectional schematic diagram which shows the manufacturing process of the photomask of embodiment of this invention.
It is a cross-sectional schematic diagram which shows the other manufacturing process of the photomask of embodiment of this invention.
It is an enlarged photograph (image data) of the center part of the thickness direction of a phase shift film in the cross-sectional SEM image of the photomask blank of Example 1. FIG.
Fig. 5B is a diagram showing a result of Fourier transforming the image data of Fig. 5A;
FIG. 5C is a diagram with symbols indicating the x-direction and the y-direction on the cross-sectional SEM of FIG. 5A.
FIG. 5D is a diagram showing the result of the Fourier transform of FIG. 5B with symbols indicating the X direction and the Y direction.
Fig. 5E is a diagram showing the relationship between the spatial frequency and signal strength derived from the Fourier transform image of Fig. 5B.
FIG. 5F is an enlarged view of the horizontal and vertical axes of the spatial frequency of FIG. 5E.
It is an enlarged photograph (image data) of the center part of the thickness direction of a phase shift film in the cross-sectional SEM image of the photomask blank of the comparative example 4. FIG.
Fig. 6B is a diagram showing a result of Fourier transforming the image data of Fig. 6A;
Fig. 6C is a diagram showing the relationship between the spatial frequency and signal strength derived from the Fourier transform image of Fig. 6B;
FIG. 6D is an enlarged view showing the horizontal and vertical axes of the spatial frequency of FIG. 6C enlarged.
Fig. 7 is an enlarged view showing the relationship between the spatial frequency and signal intensity derived from a cross-sectional SEM image of the photomask blank of Example 2;
Fig. 8 is an enlarged view showing the relationship between the spatial frequency and signal intensity derived from a cross-sectional SEM image of the photomask blank of Example 3;
9 is a cross-sectional SEM photograph (magnification: 80,000 times) of the photomask of Example 1. FIG.
10 is a cross-sectional SEM photograph of the photomask of Comparative Example 1 (magnification: 80,000 times).
11 is a cross-sectional SEM photograph of the photomask of Comparative Example 4 (magnification: 80,000 times).
12 is a cross-sectional SEM photograph (magnification: 80,000 times) of the photomask of Comparative Example 5;

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described concretely, referring drawings. In addition, the following embodiment is a form at the time of realizing this invention, and does not limit this invention within the range.

1 : is a schematic diagram which shows the film|membrane structure of the photomask blank 10 of this embodiment. The photomask blank 10 shown in FIG. 1 is the transparent substrate 20, the thin film 30 (for example, phase shift film) for pattern formation formed on the transparent substrate 20, and the thin film for pattern formation ( An etching mask film 40 formed thereon is provided.

2 : is a schematic diagram which shows the film|membrane structure of the photomask blank 10 of another embodiment. The photomask blank 10 shown in FIG. 2 is equipped with the transparent substrate 20 and the thin film 30 (for example, phase shift film) for pattern formation formed on the transparent substrate 20. As shown in FIG.

The photomask blank 10 of this embodiment can be used suitably in order to manufacture the photomask 100 used in order to manufacture a display device.

In this specification, "the thin film 30 for pattern formation" means the thin film in which a predetermined|prescribed fine pattern is formed in the photomask 100, such as a light shielding film and a phase shift film. In addition, in description of this embodiment, a phase shift film may be mentioned as an example as a specific example of the thin film 30 for pattern formation, and a phase shift film pattern may be mentioned as an example as a specific example of the thin film pattern 30a for pattern formation. Also in the thin film 30 for other pattern formation, such as a light shielding film and a light shielding film pattern, and the thin film pattern 30a for pattern formation, it is the same as a phase shift film and a phase shift film pattern.

The thin film 30 for pattern formation of the photomask blank 10 for manufacturing a display device of the present embodiment is made of a material containing titanium (Ti), silicon (Si), and nitrogen (N). The thin film 30 for pattern formation has a columnar structure. The content rate of oxygen contained in the thin film 30 for pattern formation is 7 atomic% or less. When the present inventors form a fine pattern in such thin film 30 for pattern formation, compared with the case of the phase shift film as described in patent document 3, for example, a wet etching rate is large (transmittance is the same degree) ), the cross-sectional shape of the fine pattern (thin film pattern for pattern formation) becomes a more vertical cross-sectional shape, and the fine pattern has high light resistance and resistance to light, and it is found that a fine pattern of good LER is obtained. came to the invention.

Hereinafter, about the transparent substrate 20 which comprises the photomask blank 10 for display device manufacture of this embodiment, the thin film 30 for pattern formation (for example, phase shift film), and the etching mask film 40, concrete explained as

<Transparent substrate 20>

The transparent substrate 20 is transparent to exposure light. Assuming that there is no surface reflection loss, the transparent substrate 20 has a transmittance of 85% or more with respect to the exposure light, and preferably has a transmittance of 90% or more. The transparent substrate 20 is made of a material containing silicon and oxygen. The transparent substrate 20 can be made of a glass material such as synthetic quartz glass, quartz glass, aluminosilicate glass, soda-lime glass, and low thermal expansion glass (such as SiO ₂ -TiO ₂ glass). When the transparent substrate 20 is comprised from low thermal expansion glass, the position change of the phase shift film pattern resulting from the thermal deformation of the transparent substrate 20 can be suppressed. In addition, the transparent substrate 20 used for a display device use is a board|substrate of a generally rectangular shape. Specifically, the length of the short side of the main surface of the transparent substrate 20 (the surface on which the thin film 30 for pattern formation is formed) may be 300 mm or more. In the photomask blank 10 of this embodiment, the length of the short side of the main surface can use the large size transparent substrate 20 of 300 mm or more. Using the photomask blank 10 of the present embodiment, a transfer pattern including a thin film pattern 30a for forming a fine pattern having, for example, a width dimension and/or a diameter dimension of less than 2.0 μm on a transparent substrate 20 . It is possible to manufacture a photomask 100 having By using the photomask 100 of this embodiment as described above, it is possible to stably transfer a transfer pattern including a predetermined fine pattern onto an object to be transferred.

<Thin film 30 for pattern formation>

A thin film 30 for pattern formation of the photomask blank 10 for manufacturing a display device of the present embodiment (hereinafter, simply referred to as “the photomask blank 10 of the present embodiment”) (hereinafter simply referred to as “this embodiment”) The thin film 30 for forming a pattern of a shape”) is made of a material containing titanium (Ti), silicon (Si), and nitrogen (N). This thin film 30 for pattern formation can be a phase shift film which has a phase shift function.

The thin film 30 for pattern formation is made of a titanium silicide-based material containing titanium and silicon, and may further include nitrogen.

The content rate of oxygen contained in the thin film 30 for pattern formation of this embodiment is 7 atomic% or less.

To the extent that the performance of the thin film 30 for pattern formation is not deteriorated, the thin film 30 for pattern formation may contain oxygen. Oxygen, which is a light element component, has an effect of lowering the extinction coefficient as compared with nitrogen, which is a light element component. However, when there is much oxygen content of the thin film 30 for pattern formation, there is a possibility that it may exert a bad influence about obtaining the cross section of a fine pattern close to vertical, LER, and high washing|cleaning resistance. Therefore, it is preferable that it is 7 atomic% or less, and, as for the oxygen content rate of the thin film 30 for pattern formation, it is more preferable that it is 5 atomic% or less. The thin film 30 for pattern formation may not contain oxygen.

The thin film 30 for pattern formation contains nitrogen. In the titanium silicide, nitrogen, which is a light element component, has an effect of not lowering the refractive index, as compared with oxygen, which is a light element component. Therefore, when the thin film 30 for pattern formation contains nitrogen, the film thickness for obtaining a desired phase difference (it is also mentioned a phase shift amount) can be made thin. Moreover, it is preferable that the content rate of nitrogen contained in the thin film 30 for pattern formation is 40 atomic% or more. It is more preferable that they are 40 atomic% or more and 70 atomic% or less, and, as for the content rate of nitrogen, it is still more preferable that they are 45 atomic% or more and 60 atomic% or less.

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

The atomic ratio of titanium and silicon contained in the thin film 30 for pattern formation is preferably in the range of titanium:silicon=1:1 to 1:10. If it is this range, the effect which suppresses the wet etching rate fall at the time of pattern formation of the thin film 30 for pattern formation by a columnar structure can be enlarged. In addition, the cleaning resistance of the thin film 30 for pattern formation can be improved, and it is also easy to increase the transmittance. At the time of increasing the cleaning resistance of the thin film 30 for pattern formation, the atomic ratio of titanium and silicon (titanium: silicon) contained in the thin film 30 for pattern formation is preferably in the range of 1:1 to 1:10, , more preferably in the range of 1:1 to 1:8, and still more preferably in the range of 1:1 to 1:6.

This thin film 30 for pattern formation may be comprised by the several layer, and may be comprised by the single layer. The thin film 30 for pattern formation comprised of a single layer is preferable at the point which an interface is hard to form in the thin film 30 for pattern formation, and it is easy to control a cross-sectional shape. On the other hand, the thin film 30 for pattern formation constituted by a plurality of layers is preferable in terms of easiness of film formation and the like.

<<Columnar structure>>

The thin film 30 for pattern formation of this embodiment has a columnar structure.

The columnar structure of the thin film 30 for pattern formation can be confirmed by cross-sectional SEM observation of the thin film 30 for pattern formation. That is, in the columnar structure in this embodiment, the particles of the titanium silicide compound containing titanium and silicon constituting the thin film 30 for pattern formation are in the thickness direction of the thin film 30 for pattern formation (the particles are It refers to a state with a columnar grain structure that grows toward the direction of deposition. In addition, in this embodiment, the thing whose length in the film thickness direction is longer than the length in the perpendicular|vertical direction can be made into columnar particle|grains. That is, in the thin film 30 for pattern formation, the columnar particle|grains which grow toward the film thickness direction are formed over the surface of the transparent substrate 20. As shown in FIG. In addition, the thin film 30 for pattern formation is a small portion (hereinafter simply referred to as a “small portion”) having a relatively lower density than the columnar particles by adjusting the film formation conditions (sputtering pressure, etc.) and the film composition. ) is also formed. Further, in order to effectively suppress side etching during wet etching and to further improve the pattern cross-sectional shape, as a preferred form of the columnar structure of the thin film 30 for pattern formation, columnar particles growing in the film thickness direction are It is preferable that they are formed irregularly in the direction. It is more preferable that the columnar particles of the thin film 30 for pattern formation are in a state in which the lengths in the film thickness direction are not uniform. It is preferable that the small part of the thin film 30 for pattern formation is continuously formed in the film thickness direction. Moreover, it is preferable that the small part of the thin film 30 for pattern formation is formed intermittently in the direction perpendicular|vertical to the film thickness direction.

As a preferable form of the columnar structure of the thin film 30 for pattern formation, it can represent as follows using the parameter|index which Fourier transformed about the image obtained by the said cross-sectional SEM observation. That is, in the image obtained by cross-sectional SEM observation of the cross section of the photomask blank 10 at a magnification of 80000 times, the region including the central portion in the thickness direction of the thin film for pattern formation 30 is 64 pixels long × 256 pixels wide. It is extracted as image data of a pixel, and a spatial frequency spectrum is obtained by Fourier transform this image data. The spatial frequency spectrum of the columnar structure of the thin film 30 for pattern formation obtained in this way is in a state having a signal intensity of 0.8% or more with respect to the maximum signal intensity corresponding to the origin of the spatial frequency (that is, the spatial frequency is zero). desirable. A state having such signal strength corresponds to the presence of a definite periodicity in the columnar structure. In the image of the spatial frequency spectrum obtained by Fourier transforming the image data, the center of the image corresponds to the origin. In addition, the spatial frequency spectrum becomes the maximum signal intensity at its origin (spatial frequency is zero). By making the thin film 30 for pattern formation into the columnar structure described above, the wet etching liquid easily permeates in the film thickness direction of the thin film 30 for pattern formation at the time of wet etching using a wet etching liquid. Therefore, the wet etching rate of the thin film 30 for pattern formation becomes quick, and wet etching time can be shortened significantly. Therefore, even if the thin film 30 for pattern formation is a silicon-rich titanium silicide compound, a decrease in transmittance of the transparent substrate 20 due to damage to the transparent substrate 20 caused by the wet etching solution does not occur. Moreover, since the thin film 30 for pattern formation has a columnar structure which grows in the film thickness direction, the side etching at the time of wet etching is suppressed. Therefore, the pattern cross-sectional shape of the thin film pattern 30a for pattern formation becomes favorable. Moreover, LER of the thin film pattern 30a for pattern formation becomes favorable.

In the thin film 30 for pattern formation, when a signal having a signal intensity of 0.8% or more with respect to the maximum signal intensity of the spatial frequency spectrum distribution obtained by Fourier transform assumes that the maximum spatial frequency is 100%, from the origin of the spatial frequency It is desirable to be at a spatial frequency separated by at least 6.7%. The coordinates in the transverse direction (for example, the direction of the dashed-dotted line X in Fig. 5D) passing through the center (origin) of the image of the spatial frequency spectrum are in the transverse direction (e.g., in Fig. 5C) of the image data of the Fourier transform source. In the cross-sectional view of the thin film 30 for pattern formation formed on the transparent substrate 20 in the x direction, it corresponds to the spatial frequency component of the transparent substrate 20 and the direction parallel to the boundary line of the thin film 30 for pattern formation) do. Coordinates in the longitudinal direction (for example, the direction of the dashed-dotted line Y in Fig. 5D) passing through the center (origin) of the image of the spatial frequency spectrum are in the longitudinal direction of the image data of the Fourier transform source (e.g., in Fig. 5C). It is a y-direction and corresponds to the spatial frequency component of the film thickness direction of the thin film 30 for pattern formation). In either direction, the corresponding spatial frequency increases from the center of the image of the spatial frequency spectrum toward the outer periphery. The periodicity of the columnar structure of the thin film 30 for pattern formation is the signal intensity of the spatial frequency corresponding to the lateral direction (eg, the x direction in FIG. 5C ) (eg, the space in the direction of the dashed-dotted line X in FIG. 5D ) It is preferable to use the signal strength of frequency) as an index. In this case, the maximum spatial frequency is the maximum value in the coordinates in the horizontal direction passing through the center of the image of the spatial frequency spectrum (the outer edge of the horizontal direction in the image, in the example of Fig. 5D, the dash-dotted line X passing through the center of the image) signal intensity at a position of ±100% of ). In addition, to say that a signal having a signal strength of 0.8% or more with respect to the maximum signal strength is separated by 6.7% or more, for example, the image data of the Fourier transform source as shown in Fig. 5A contains a spatial frequency component higher than a certain level. indicates that there is That is, such a state has shown the state in which the thin film 30 for pattern formation is a fine columnar structure. As described above, the line edge roughness (LER) of the thin film pattern 30a for pattern formation obtained by forming the thin film 30 for pattern formation by wet etching decreases as the spatial frequency is at a position further away from the origin, be a good value.

<<Etch rate>>

The thin film 30 for pattern formation of the photomask blank 10 for manufacturing a display device of the present embodiment is made of a material containing titanium (Ti), silicon (Si), and nitrogen (N), and has a columnar structure. Therefore, it has a high etching rate. Specifically, it has a high etching rate with respect to the following etching liquids A and B used in the etching of the photomask 100. As shown in FIG.

As etching liquid A, the etching liquid containing at least 1 fluorine compound selected from hydrofluoric acid, hydrosilicic acid, and ammonium hydrofluoride, at least 1 oxidizing agent selected from hydrogen peroxide, nitric acid, and sulfuric acid, and water is mentioned.

As etching liquid B, the etching liquid containing ammonium hydrogen fluoride, hydrogen peroxide, at least 1 oxidizing agent chosen from phosphoric acid, sulfuric acid, and nitric acid, and water is mentioned.

The thin film 30 for pattern formation of this embodiment has an etching rate of 2.5 nm/min or more and 12.0 nm/min when etched using an etchant (etchant A) containing ammonium hydrogen fluoride, hydrogen peroxide, and water. It is preferable that it is below, and it is more preferable that it is 4.0 nm/min or more and 8.0 nm/min or less. As etching liquid A, the etching liquid containing 0.1 to 0.8 weight% of ammonium hydrogenfluoride, 0.5 to 4.0 weight% of hydrogen peroxide, and water can be used.

<<Transmittance and phase difference of thin film 30 for pattern formation>>

In the photomask blank 10 for manufacturing a display device of the present embodiment, the thin film 30 for pattern formation has a transmittance of 1% or more and 80% or less and a phase difference of 160° or more and 200° or less with respect to a representative wavelength of exposure light. It is preferable that it is a phase shift film with a characteristic. Unless otherwise specified, the transmittance|permeability in this specification points out what converted the transmittance|permeability of a transparent substrate as a reference|standard (100%).

When the thin film 30 for pattern formation is a phase shift film, the thin film 30 for pattern formation has the reflectance with respect to the light which injects from the transparent substrate 20 side (it may describe as back surface reflectance hereafter) It has a function to adjust, and a function to adjust transmittance and phase difference with respect to exposure light.

The transmittance of the thin film 30 for pattern formation with respect to the exposure light satisfies a value required as the thin film 30 for pattern formation. The transmittance of the thin film 30 for pattern formation is preferably 1% or more and 80% or less, and more preferably 15% or more with respect to light of a predetermined wavelength (hereinafter referred to as a representative wavelength) included in the exposure light. It is 65 % or less, More preferably, it is 20 % or more and 60 % or less. That is, when the exposure light is a composite light including light in a wavelength range of 313 nm or more and 436 nm or less, the thin film 30 for pattern formation has the transmittance described above with respect to light having a representative wavelength included in the wavelength range. For example, when the exposure light is a composite light including i-line, h-line, and g-line, the thin film 30 for pattern formation may have the above-described transmittance for any of the i-line, h-line, and g-line. . The representative wavelength can be, for example, h-line with a wavelength of 405 nm. By having such a characteristic with respect to h-line, when a composite light including i-line, h-line, and g-line is used as exposure light, a similar effect can be expected with respect to transmittance at the wavelengths of i-line and g-line.

In addition, when the exposure light is monochromatic light selected from a wavelength range of 313 nm or more and 436 nm or less by cutting a certain wavelength region with a filter or the like, and monochromatic light selected from a wavelength range of 313 nm or more and 436 nm or less, the thin film 30 for pattern formation is the single It has the above-mentioned transmittance|permeability with respect to monochromatic light of a wavelength.

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

The phase difference of the thin film 30 for pattern formation with respect to exposure light satisfies the value required as the thin film 30 for pattern formation. The phase difference of the thin film 30 for pattern formation is preferably 160 degrees or more and 200 degrees or less, and more preferably 170 degrees or more and 190 degrees or less with respect to light of a representative wavelength included in the exposure light. With this property, the phase of light of a representative wavelength included in the exposure light can be changed to 160 degrees or more and 200 degrees or less. For this reason, a phase difference of 160 degrees or more and 200 degrees or less arises between the light of the representative wavelength transmitted through the thin film 30 for pattern formation and the light of the representative wavelength transmitted only through the transparent substrate 20 . That is, when the exposure light is a composite light including light in a wavelength range of 313 nm or more and 436 nm or less, the thin film 30 for pattern formation has the above-described retardation with respect to light having a representative wavelength included in the wavelength range. For example, when the exposure light is a composite light including i-line, h-line, and g-line, the thin film 30 for pattern formation may have the above-described phase difference with respect to any of the i-line, h-line, and g-line. . The representative wavelength can be, for example, h-line with a wavelength of 405 nm. By having such a characteristic with respect to the h-line, a similar effect can be expected with respect to the phase difference at the wavelengths of the i-line and the g-line when the composite light including the i-line, the h-line and the g-line is used as the exposure light.

A phase difference can be measured using a phase shift amount measuring apparatus etc.

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

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

The thin film 30 for pattern formation can be formed by a well-known film-forming method, such as a sputtering method.

<Etching mask film 40>

It is preferable that the photomask blank 10 for display device manufacture of this embodiment is provided with the etching mask film 40 different from the etching selectivity with respect to the thin film 30 for pattern formation on the thin film 30 for pattern formation. do.

The etching mask film 40 is disposed on the upper side of the thin film 30 for pattern formation, and has etching resistance to an etchant that etches the thin film 30 for pattern formation (etch selectivity with respect to the thin film 30 for pattern formation). It is made of different) materials. In addition, the etching mask film 40 may have a function of blocking transmission of exposure light. In addition, the etching mask film 40 has a film surface reflectance such that the film surface reflectance of the pattern forming thin film 30 with respect to the light incident from the pattern forming thin film 30 side becomes 15% or less in a wavelength range of 350 nm to 436 nm. It may have a function to reduce

The etching mask film 40 is preferably made of a chromium-based material containing chromium (Cr). It is more preferable that the etching mask film 40 is made of a material containing chromium and substantially not containing silicon. Substantially not containing silicon means that the silicon content is less than 2% (however, the composition gradient region at the interface between the pattern forming thin film 30 and the etching mask film 40 is excluded). More specifically, examples of the chromium-based material include a material containing chromium (Cr) or chromium (Cr), and at least one of oxygen (O), nitrogen (N), and carbon (C). Moreover, as a chromium-type material, the material containing chromium (Cr), at least any one of oxygen (O), nitrogen (N), and carbon (C), and also containing fluorine (F) is mentioned. For example, as a material constituting the etching mask film 40 , Cr, CrO, CrN, CrF, CrCO, CrCN, CrON, CrCON, and CrCONF are exemplified.

The etching mask film 40 can be formed by a well-known film-forming method, such as a sputtering method.

When the etching mask film 40 has a function of blocking the transmission of exposure light, in the portion where the thin film 30 for pattern formation and the etching mask film 40 are laminated, the optical density of the exposure light is preferably It is 3 or more, More preferably, it is 3.5 or more, More preferably, it is 4 or more. The optical density can be measured using a spectrophotometer, an OD meter, or the like.

The etching mask film 40 may be formed of a single film having a uniform composition according to a function. In addition, the etching mask film 40 may be formed of a plurality of films having different compositions. Further, the etching mask film 40 may be formed of a single film whose composition continuously changes in the thickness direction.

Moreover, the photomask blank 10 of this embodiment shown in FIG. 1 is equipped with the etching mask film 40 on the thin film 30 for pattern formation. The photomask blank 10 of this embodiment is provided with the etching mask film 40 on the thin film 30 for pattern formation, and the photomask blank 10 of the structure provided with the resist film on the etching mask film 40. ) is included.

<Method for manufacturing the photomask blank 10>

Next, the manufacturing method of the photomask blank 10 of embodiment shown in FIG. 1 is demonstrated. The photomask blank 10 shown in FIG. 1 is manufactured by performing the following thin film formation process for pattern formation, and an etching mask film formation process. The photomask blank 10 shown in FIG. 2 is manufactured by the thin film formation process for pattern formation.

Hereinafter, each process is demonstrated in detail.

<<Thin film formation process for pattern formation>>

First, the transparent substrate 20 is prepared. The material of the transparent substrate 20 should just be transparent with respect to exposure light. Specifically, the transparent substrate 20 may be made of a glass material selected from synthetic quartz glass, quartz glass, aluminosilicate glass, soda-lime glass, and low thermal expansion glass (SiO ₂ -TiO ₂ glass, etc.). .

Next, a thin film 30 for pattern formation is formed on the transparent substrate 20 by sputtering.

The film formation of the thin film 30 for pattern formation can be performed in a predetermined|prescribed sputtering gas atmosphere using a predetermined|prescribed sputtering target. The predetermined sputtering target is, for example, a titanium silicide target containing titanium and silicon, which are the main components of the material constituting the thin film 30 for pattern formation, or a titanium silicide target containing titanium, silicon, and nitrogen. The predetermined sputtering gas atmosphere is, for example, a sputtering gas atmosphere made of an inert gas containing at least one selected from the group consisting of helium gas, neon gas, argon gas, krypton gas and xenon gas, or the inert gas; It is a sputtering gas atmosphere which consists of nitrogen gas and the mixed gas which contains the gas selected from the group which consists of oxygen gas, carbon dioxide gas, nitrogen monoxide gas, and nitrogen dioxide gas in some cases. Formation of the thin film 30 for pattern formation can be performed in the state used as the gas pressure in the film-forming chamber at the time of sputtering being 0.43 Pa or more and 3.0 Pa or less, Preferably it is 0.43 Pa or more and 3.0 Pa or less. Since titanium is an element significantly lighter than molybdenum and zirconium, which are other transition elements, a columnar structure can be formed in the thin film 30 for pattern formation by setting the gas pressure range in this way. By this columnar structure, while being able to suppress the side etching at the time of the pattern formation mentioned later, a high etching rate can be achieved. It is preferable that the atomic ratio of titanium and silicon of a titanium silicide target is the range of titanium:silicon=1:3 to 1:7. By using the titanium silicide target of such an atomic ratio, the effect of suppressing the decrease in the wet etching rate by the columnar structure is large, the light resistance and chemical resistance of the thin film 30 for pattern formation can be improved, and it is also easy to increase the transmittance.

The composition and thickness of the thin film 30 for pattern formation are adjusted so that the thin film 30 for pattern formation has the above-described retardation and transmittance. The composition of the thin film 30 for pattern formation can be controlled by the content ratio of elements constituting the sputtering target (for example, the ratio of titanium content and silicon content), the composition and flow rate of the sputtering gas, and the like. The thickness of the thin film 30 for pattern formation can be controlled by sputtering power, sputtering time, and the like. In addition, it is preferable to form the thin film 30 for pattern formation using an in-line type sputtering apparatus. When a sputtering apparatus is an in-line sputtering apparatus, the thickness of the thin film 30 for pattern formation is controllable also with the conveyance speed of a board|substrate. Thus, control is performed so that the nitrogen content of the thin film 30 for pattern formation may be set to 40 atomic% or more and 70 atomic% or less.

When the thin film 30 for pattern formation consists of a single film|membrane, the above-mentioned film-forming process is performed only once, adjusting the composition and flow volume of a sputtering gas suitably. When the thin film 30 for pattern formation consists of a plurality of films having different compositions, the above-described film forming process is performed a plurality of times by appropriately adjusting the composition and flow rate of the sputtering gas. You may form the thin film 30 for pattern formation into a film using the target from which the content rate of the element which comprises a sputtering target differs. When performing a film-forming process in multiple times, you may change the sputtering power applied to a sputtering target for every film-forming process.

<<Surface treatment process>>

The thin film 30 for pattern formation may be made of a titanium silicide material (titanium silicide oxynitride) containing oxygen in addition to titanium, silicon, and nitrogen. However, content of oxygen is more than 0 atomic% and 7 atomic% or less. In this way, when the thin film 30 for pattern formation contains oxygen, in order to suppress permeation by the etching solution due to the presence of titanium oxide on the surface of the thin film 30 for pattern formation, the thin film for pattern formation ( You may make it perform the surface treatment process of adjusting the state of surface oxidation of 30). In addition, when the thin film 30 for pattern formation is made of titanium silicide nitride containing titanium, silicon, and nitrogen, the content of titanium oxide is small compared to the above-described titanium silicide material containing oxygen. Therefore, when the material of the thin film 30 for pattern formation is titanium silicide nitride, the said surface treatment process may be made to perform, and it is not necessary to perform it.

As a surface treatment step for adjusting the surface oxidation state of the thin film 30 for pattern formation, a method of surface treatment with an acidic aqueous solution, a method of surface treatment with an alkaline aqueous solution, a method of surface treatment with dry treatment such as ashing, etc. can be heard

In this way, the photomask blank 10 of this embodiment can be obtained.

<<Etching mask film forming process>>

The photomask blank 10 of the present embodiment may further include an etching mask film 40 . The following etching mask film formation process is further performed. In addition, it is preferable that the etching mask film 40 is comprised from the material which contains chromium and does not contain substantially silicon.

After the thin film formation step for pattern formation, a surface treatment for adjusting the surface oxidation state of the surface of the pattern formation thin film 30 is performed as needed, and thereafter, etching is performed on the pattern formation thin film 30 by sputtering. A mask film 40 is formed. The etching mask film 40 is preferably formed using an in-line sputtering apparatus. When the sputtering apparatus is an in-line sputtering apparatus, the thickness of the etching mask film 40 is controllable also by the conveyance speed of the transparent substrate 20 .

The etching mask film 40 is formed by using a sputter target containing chromium or a chromium compound (chromium oxide, chromium nitride, chromium carbide, chromium oxynitride, chromium nitride carbide, chromium oxynitride carbide, etc.) with an inert gas. It can carry out in the sputtering gas atmosphere which consists of a sputtering gas atmosphere, or the sputtering gas atmosphere which consists of a mixed gas of an inert gas and an active gas. The inert gas may include, for example, at least one selected from the group consisting of helium gas, neon gas, argon gas, krypton gas, and xenon gas. The active gas may include at least one selected from the group consisting of oxygen gas, nitrogen gas, nitrogen monoxide gas, nitrogen dioxide gas, carbon dioxide gas, hydrocarbon gas, and fluorine gas. Examples of the hydrocarbon-based gas include methane gas, butane gas, propane gas, and styrene gas. By adjusting the gas pressure in the film formation chamber at the time of sputtering, similarly to the thin film 30 for pattern formation, the etching mask film 40 can be made into a columnar structure. Thereby, while being able to suppress the side etching at the time of the pattern formation mentioned later, a high etching rate can be achieved.

When the etching mask film 40 is formed of a single film having a uniform composition, the above-described film forming process is performed only once without changing the composition and flow rate of the sputtering gas. When the etching mask film 40 is formed of a plurality of films having different compositions, the above-described film formation process is performed a plurality of times by changing the composition and flow rate of the sputtering 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 sputtering gas together with the elapsed time of the film formation process.

In this way, the photomask blank 10 of the present embodiment having the etching mask film 40 can be obtained.

In addition, since the photomask blank 10 shown in FIG. 1 is equipped with the etching mask film 40 on the thin film 30 for pattern formation, when manufacturing the photomask blank 10, it is an etching mask film. A forming process is performed. In addition, when manufacturing the photomask blank 10 provided with the etching mask film 40 on the thin film 30 for pattern formation, and provided with the resist film on the etching mask film 40, after an etching mask film formation process, , a resist film is formed on the etching mask film 40 . In addition, in the photomask blank 10 shown in FIG. 2, when manufacturing the photomask blank 10 provided with the resist film on the thin film 30 for pattern formation, after the thin film formation process for pattern formation, a resist film to form

As for the photomask blank 10 of embodiment shown in FIG. 1, the etching mask film 40 is formed on the thin film 30 for pattern formation. At least this thin film 30 for pattern formation has a columnar structure. Moreover, in the photomask blank 10 of embodiment shown in FIG. 2, the thin film 30 for pattern formation is formed. This thin film 30 for pattern formation has a columnar structure.

In the photomask blank 10 of the embodiment shown in Figs. 1 and 2, when the thin film 30 for pattern formation is patterned by wet etching, etching in the film thickness direction is promoted while side etching is suppressed. . Therefore, the cross-sectional shape of the thin film pattern 30a for pattern formation obtained by patterning is favorable and has a desired transmittance|permeability (for example, the transmittance|permeability is high). By using the photomask blank 10 of embodiment, the thin film pattern 30a for pattern formation can be formed in a short etching time. Therefore, by using the photomask blank 10 of the present embodiment, there is no decrease in transmittance of the transparent substrate 20 due to damage to the transparent substrate 20 caused by the wet etching solution, and there is no decrease in the transmittance of the transparent substrate 20 for forming a high-precision pattern. The photomask 100 capable of transferring the pattern 30a with high precision may be manufactured.

<Method for manufacturing the photomask 100>

Next, the manufacturing method of the photomask 100 of this embodiment is demonstrated.

3 : is a schematic diagram which shows the manufacturing method of the photomask 100 of this embodiment. 4 : is a schematic diagram which shows the other manufacturing method of the photomask 100 of this embodiment.

<<The manufacturing method of the photomask 100 shown in FIG. 3>>

The manufacturing method of the photomask 100 shown in FIG. 3 is a method of manufacturing the photomask 100 using the photomask blank 10 shown in FIG. The manufacturing method of the photomask 100 shown in FIG. 3 includes the process of preparing the photomask blank shown in FIG. 1, forming a resist film on the etching mask film 40, and the resist film pattern formed by the resist film. A process of forming an etching mask film pattern (first etching mask film pattern 40a) on the thin film 30 for pattern formation by wet etching the etching mask film 40 using as a mask, and the etching mask film pattern ( Using the first etching mask film pattern 40a as a mask, the thin film 30 for pattern formation is wet-etched to form a transfer pattern on the transparent substrate 20 . In addition, the pattern for transcription|transfer in this specification is obtained by patterning the at least 1 optical film formed on the transparent substrate 20. As shown in FIG. The optical film may be the thin film 30 for pattern formation and/or the etching mask film 40, and may further include other films (light-shielding film, reflection suppressing film, conductive film, etc.). . That is, the transfer pattern may include a patterned thin film for pattern formation and/or an etching mask film, and may further include patterned other films.

In the manufacturing method of the photomask 100 shown in FIG. 3, specifically, a resist film is formed on the etching mask film 40 of the photomask blank 10 shown in FIG. Next, the resist film pattern 50 is formed by drawing and developing a desired pattern on the resist film (refer to Fig. 3A, the formation step of the first resist film pattern 50). Next, using the resist film pattern 50 as a mask, the etching mask film 40 is wet-etched to form an etching mask film pattern 40a on the pattern forming thin film 30 (Fig. 3(b)). ), the process of forming the first etching mask film pattern 40a). Next, using the etching mask film pattern 40a as a mask, the thin film 30 for pattern formation is wet-etched to form a thin film pattern 30a for pattern formation on the transparent substrate 20 (FIG. 3(( c) See, the formation process of the thin film pattern 30a for pattern formation). Thereafter, a process of forming the second resist film pattern 60 and a process of forming the second etching mask film pattern 40b may be further included (see FIGS. 3D and 3E ).

More specifically, in the step of forming the first resist film pattern 50 , first, a resist film is formed on the etching mask film 40 of the photomask blank 10 of the present embodiment shown in FIG. 1 . The resist film material to be used is not particularly limited. The resist film may be photosensitive with respect to a laser beam having any wavelength selected from, for example, a wavelength range of 350 nm to 436 nm, which will be described later. In addition, the resist film may be either positive type or negative type.

Thereafter, a desired pattern is drawn on the resist film using a laser beam having a certain wavelength selected from a wavelength range of 350 nm to 436 nm. The pattern drawn on the resist film is a pattern formed on the thin film 30 for pattern formation. As a pattern to be drawn on a resist film, a line and space pattern and a hole pattern are mentioned.

Thereafter, the resist film is developed with a predetermined developer to form a first resist film pattern 50 on the etching mask film 40 as shown in FIG. 3A .

<<<Step of forming the first etching mask film pattern 40a >>>

In the step of forming the first etching mask film pattern 40a, first, the etching mask film 40 is etched using the first resist film pattern 50 as a mask to form the first etching mask film pattern 40a. . The etching mask film 40 may be formed of a chromium-based material containing chromium (Cr). When the etching mask film 40 has a columnar structure, it is preferable at the point which an etching rate is quick and side etching can be suppressed. The etching solution for etching the etching mask film 40 is not particularly limited as long as it can selectively etch the etching mask film 40 . Specifically, the etching liquid containing cerium ammonium nitrate and perchloric acid is mentioned.

Thereafter, the first resist film pattern 50 is removed using a resist stripping solution or by ashing, as shown in Fig. 3B. In some cases, the formation process of the thin film pattern 30a for the next pattern formation may be performed without peeling the 1st resist film pattern 50 .

<<< Formation process of thin film pattern 30a for pattern formation >>>

In the formation process of the thin film pattern 30a for pattern formation, the thin film 30 for pattern formation is wet-etched using the 1st etching mask film pattern 40a as a mask, and, as shown in FIG. 3(c), Similarly, a thin film pattern 30a for pattern formation is formed. As the thin film pattern 30a for pattern formation, a line and space pattern and a hole pattern are mentioned. The etching solution for etching the thin film 30 for pattern formation is not particularly limited as long as it can selectively etch the thin film 30 for pattern formation. For example, the above-mentioned etching liquid A (etching liquid etc. containing ammonium hydrogen fluoride and hydrogen peroxide) and etching liquid B (etching liquid etc. containing ammonium fluoride, phosphoric acid, and hydrogen peroxide, etc.) are mentioned.

In order to make the cross-sectional shape of the thin film pattern 30a for pattern formation favorable, wet etching is longer than the time (just etching time) until the transparent substrate 20 is exposed in the thin film pattern 30a for pattern formation. It is preferable to carry out with time (over etching time). As the over-etching time, in consideration of the influence on the transparent substrate 20, etc., it is preferable to set the just etching time to the time of adding 20% of the just etching time, and 10% of the just etching time. It is more preferable to set it within the additional time.

<<< Formation process of the second resist film pattern 60 >>>

In the process of forming the second resist film pattern 60 , first, a resist film covering the first etching mask film pattern 40a is formed. The resist film material to be used is not particularly limited. For example, what is necessary is just to be photosensitive with respect to the laser beam which has any wavelength selected from the wavelength range of 350 nm - 436 nm mentioned later. In addition, the resist film may be either positive type or negative type.

Thereafter, a desired pattern is drawn on the resist film using a laser beam having a certain wavelength selected from a wavelength range of 350 nm to 436 nm. The pattern drawn on the resist film is a light-shielding band pattern that shields the outer periphery of the region where the pattern-forming thin film pattern 30a is formed, and a light-shielding band pattern that blocks the central portion of the pattern-forming thin film pattern 30a. . Note that the pattern drawn on the resist film may be a pattern without a light-shielding band pattern that blocks light at the center of the pattern-forming thin-film pattern 30a depending on the transmittance of the pattern-forming thin film 30 with respect to exposure light. .

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

<<< Formation process of second etching mask film pattern 40b >>>

In the step of forming the second etching mask film pattern 40b, the first etching mask film pattern 40a is etched using the second resist film pattern 60 as a mask, and as shown in FIG. 3E , , a second etching mask layer pattern 40b is formed. The first etching mask layer pattern 40a may be formed of a chromium-based material including chromium (Cr). The etching solution for etching the first etching mask film pattern 40a is not particularly limited as long as it can selectively etch the first etching mask film pattern 40a. For example, the etching liquid containing cerium ammonium nitrate and perchloric acid is mentioned.

Thereafter, the second resist film pattern 60 is removed using a resist stripping solution or by ashing.

In this way, the photomask 100 can be obtained. That is, the transfer pattern included in the photomask 100 according to the present embodiment may include the thin film pattern 30a for pattern formation and the second etching mask film pattern 40b.

In addition, in the above description, the case where the etching mask film 40 has a function to block transmission of exposure light has been described. In the case where the etching mask film 40 has only a function of a hard mask for etching the thin film 30 for pattern formation, in the above description, the formation process of the second resist film pattern 60; 2 The process of forming the etching mask film pattern 40b is not performed. In this case, after the formation process of the thin film pattern 30a for pattern formation, the photomask 100 is manufactured by peeling the 1st etching mask film pattern 40a. That is, the transfer pattern included in the photomask 100 may be composed of only the thin film pattern 30a for pattern formation.

According to the manufacturing method of the photomask 100 of this embodiment, since the photomask blank 10 shown in FIG. 1 is used, etching time can be shortened and the thin film pattern 30a for pattern formation with favorable cross-sectional shape. ) can be formed. Accordingly, it is possible to manufacture the photomask 100 capable of transferring the transfer pattern including the high-precision thin film pattern 30a for pattern formation with high precision. The photomask 100 manufactured as described above may respond to line and space patterns and/or miniaturization of contact holes.

<<The manufacturing method of the photomask 100 shown in FIG. 4>>

The manufacturing method of the photomask 100 shown in FIG. 4 is a method of manufacturing the photomask 100 using the photomask blank 10 shown in FIG. The manufacturing method of the photomask 100 shown in FIG. 4 includes the process of preparing the photomask blank 10 shown in FIG. 2, and forming a resist film on the thin film 30 for pattern formation, and forming with a resist film. A process of forming a transfer pattern on the transparent substrate 20 by wet-etching the thin film 30 for pattern formation using one resist film pattern as a mask is included.

Specifically, in the method for manufacturing the photomask 100 shown in FIG. 4 , a resist film is formed on the photomask blank 10 . Next, the resist film pattern 50 is formed by drawing and developing a desired pattern on the resist film (FIG. 4(a), the formation process of the 1st resist film pattern 50). Next, using the resist film pattern 50 as a mask, the thin film 30 for pattern formation is wet-etched to form a thin film pattern 30a for pattern formation on the transparent substrate 20 (Fig. 4(b)). ) and (c), the formation process of the thin film pattern 30a for pattern formation).

More specifically, in the resist film pattern forming step, first, a resist film is formed on the pattern forming thin film 30 of the photomask blank 10 of the present embodiment shown in FIG. 2 . The resist film material used is the same as that described above. In addition, before forming a resist film, if necessary, in order to improve the adhesiveness between the thin film 30 for pattern formation and a resist film, the thin film 30 for pattern formation may be surface-modified. In the same manner as above, after the resist film is formed, a desired pattern is drawn on the resist film using a laser beam having a certain wavelength selected from a wavelength range of 350 nm to 436 nm. Thereafter, the resist film is developed with a predetermined developer, and a resist film pattern 50 is formed on the thin film 30 for pattern formation as shown in FIG. 4A .

<<< Formation process of thin film pattern 30a for pattern formation >>>

In the formation process of the thin film pattern 30a for pattern formation, the thin film 30 for pattern formation is etched using the resist film pattern as a mask, and, as shown in FIG.4(b), the thin film pattern 30a for pattern formation is used. ) to form The etching liquid and overetching time which etch the thin film pattern 30a for pattern formation and the thin film 30 for pattern formation are the same as the description in embodiment shown in FIG. 3 mentioned above.

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

In this way, the photomask 100 can be obtained. In addition, although the pattern for transcription|transfer which the photomask 100 which concerns on this embodiment has is comprised only with the thin film pattern 30a for pattern formation, it may further include other film|membrane patterns. Examples of the other film include a film that suppresses reflection, a conductive film, and the like.

According to the manufacturing method of the photomask 100 of this embodiment, since the photomask blank 10 shown in FIG. 2 is used, the transparent substrate 20 resulting from damage to the transparent substrate by the wet etching solution. There is no fall of the transmittance|permeability, etching time can be shortened, and the thin film pattern 30a for pattern formation with a favorable cross-sectional shape can be formed. Accordingly, it is possible to manufacture the photomask 100 capable of transferring the transfer pattern including the high-precision thin film pattern 30a for pattern formation with high precision. The photomask 100 manufactured as described above may respond to line and space patterns and/or miniaturization of contact holes.

<Method for manufacturing display device>

The manufacturing method of the display device of this embodiment is demonstrated. In the manufacturing method of the display device of this embodiment, the photomask 100 of this embodiment mentioned above is mounted on the mask stage of an exposure apparatus, and the transfer pattern formed on the photomask 100 for display device manufacture is applied to a display device. It has an exposure process of exposing and transferring to the resist formed on the substrate of a dragon.

Specifically, the manufacturing method of the display device of the present embodiment includes a step of loading a photomask 100 manufactured using the photomask blank 10 described above on a mask stage of an exposure apparatus (mask loading step); A step (exposure step) of exposing and transferring a transfer pattern onto a resist film on a substrate for a display device is included. Hereinafter, each process is demonstrated in detail.

<<Loading process>>

In a loading process, the photomask 100 of this embodiment is mounted on the mask stage of an exposure apparatus. Here, the photomask 100 is disposed so as to face the resist film formed on the substrate for the display device through the projection optical system of the exposure apparatus.

<<Pattern transfer process>>

In the pattern transfer step, the photomask 100 is irradiated with exposure light to transfer the transfer pattern including the thin film pattern 30a for pattern formation onto a resist film formed on a substrate for a display device. The exposure light is composite light including light of a plurality of wavelengths selected from a wavelength region of 313 nm to 436 nm, or monochromatic light selected by cutting a certain wavelength region from a wavelength region of 313 nm to 436 nm with a filter or the like, or a wavelength of 313 nm to 436 nm Monochromatic light emitted from a light source having an area. For example, the exposure light is a composite light including at least one of i-line, h-line, and g-line, or monochromatic light of i-line. By using the composite light as the exposure light, the exposure light intensity can be increased to improve the throughput. Therefore, the manufacturing cost of the display device can be lowered.

According to the manufacturing method of the display device of the present embodiment, it is possible to manufacture a high-definition display device having a high resolution and a fine line and space pattern and/or a contact hole.

In addition, in the above embodiment, the case of using the photomask blank 10 which has the thin film 30 for pattern formation, and the photomask 100 which has the thin film pattern 30a for pattern formation was demonstrated. The thin film 30 for pattern formation may be a phase shift film which has a phase shift effect, or a light shielding film, for example. Therefore, the photomask 100 of this embodiment contains the binary mask which has a phase shift mask which has a phase shift film pattern, and a light shielding film pattern. In addition, the photomask blank 10 of this embodiment contains the phase shift photomask blank used as the raw material of a phase shift mask and a binary mask, and a binary photomask blank.

<Example>

Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited to these.

(Example 1)

In order to produce the photomask blank 10 of Example 1, first, as the transparent substrate 20, a synthetic quartz glass substrate of size 1214 (1220 mm x 1400 mm) was prepared.

Then, the synthetic quartz glass substrate was mounted on a tray (not shown) with the main surface facing downward, and was carried in into the chamber of an in-line sputtering apparatus.

In order to form the thin film 30 for pattern formation on the main surface of the transparent substrate 20, first, in a state where the pressure of the sputtering gas in the first chamber is 0.45 Pa, argon (Ar) gas and nitrogen (N ₂ ) A mixed gas composed of gas was introduced. Then, using a first sputtering target (titanium:silicon=1:6.7) containing titanium and silicon, titanium silicide containing titanium, silicon, and nitrogen on the main surface of the transparent substrate 20 by reactive sputtering of nitride was deposited. In this way, a thin film 30 for pattern formation with a film thickness of 171 nm made of a nitride of titanium silicide was formed. In addition, this thin film 30 for pattern formation is a phase shift film which has a phase shift effect.

Next, the transparent substrate 20 with the thin film 30 for pattern formation was carried in into the 2nd chamber, and the mixed gas of argon (Ar) gas and nitrogen (N2) gas was introduce|transduced into the _2nd chamber. And chromium nitride (CrN layer) containing chromium and nitrogen was formed on the thin film 30 for pattern formation by reactive sputtering using the 2nd sputtering target which consists of chromium. Next, a mixed gas of argon (Ar) gas and methane (CH ₄ ) gas is introduced in a state in which the inside of the third chamber is set to a predetermined degree of vacuum, and using a third sputtering target made of chromium, reactive sputtering is performed. A chromium carbide (CrC layer) containing chromium and carbon was formed on CrN. Finally, a mixed gas of argon (Ar) gas, methane (CH ₄ ) gas, nitrogen (N ₂ ) gas, and oxygen (O ₂ ) gas is introduced in the fourth chamber with a predetermined vacuum degree. Then, using a fourth sputtering target made of chromium, a chromium carbonization oxynitride (CrCON layer) containing chromium, carbon, oxygen, and nitrogen was formed on CrC by reactive sputtering. As described above, on the thin film 30 for pattern formation, the etching mask film 40 having a stacked structure of a CrN layer, a CrC layer, and a CrCON layer was formed.

In this way, the photomask blank 10 in which the thin film 30 for pattern formation and the etching mask film 40 were formed on the transparent substrate 20 was obtained.

(Examples 2 and 3, and Comparative Examples 1 to 5)

In Table 1, the manufacturing conditions of the thin film 30 for pattern formation of Examples 2 and 3, and Comparative Examples 1-5 are shown. Except for the manufacturing conditions of the thin film 30 for pattern formation, the thin film 30 for pattern formation and the etching mask film 40 were formed on the transparent substrate 20 similarly to Example 1, Example 2 and 3 , and photomask blanks 10 of Comparative Examples 1 to 5 were obtained. However, as shown in Table 1, the manufacturing conditions of the thin film 30 for pattern formation of Examples 2 and 3 and Comparative Examples 1 to 5 are different from the manufacturing conditions of the thin film 30 for pattern formation of Example 1 different. Therefore, the thin film 30 for pattern formation of Examples 2 and 3 and Comparative Examples 1 to 5 is different from the thin film 30 for pattern formation of Example 1. FIG. In Table 1, that the mixed gas is described as Ar+N ₂ indicates that a mixed gas of argon (Ar) and nitrogen (N ₂ ) is used during sputtering, and the mixed gas is Ar+N ₂ +He What is described shows that a mixed gas of argon (Ar), nitrogen (N ₂ ), and helium (He) is used, and that where the mixed gas is described as Ar+N ₂ +He+NO is argon (Ar) and It shows that the mixed gas _of nitrogen (N2), helium (He), and nitrogen monoxide (NO) was used. In addition, the film thickness of each thin film for pattern formation of each Example and a comparative example was adjusted suitably so that it might become a desired optical characteristic (transmittance, retardation). Moreover, the transmittance|permeability of Example 1 is 50 %, and it was examined that the transmittance|permeability of Comparative Example 1 (molybdenum silicide type|system|group) sets it as about 50 % thing for comparison. However, it was difficult to form a thin film for pattern formation having a transmittance of 50% with a molybdenum silicide-based film material. Therefore, the transmittance|permeability of the comparative example 1 was made into 40 %.

(Evaluation of the photomask blank 10)

The thin film 30 for pattern formation of the photomask blank 10 of the above-described Examples and Comparative Examples was evaluated according to the following items.

<Measurement of transmittance and phase difference>

Transmittance (wavelength: 365 nm, 436 nm) with respect to the surface of the thin film 30 for pattern formation (the thin film 30 for pattern formation) of the photomask blank 10 of the Examples and Comparative Examples by MPM-100 manufactured by Lasertec Co., Ltd. , the phase difference (wavelengths: 365nm, 436nm) was measured, and converted into a value of wavelength 405nm in the weighted average. For the measurement of the transmittance and phase difference of the thin film for pattern formation 30, the thin film 30 for pattern formation in which the thin film 30 for pattern formation is formed on the main surface of a synthetic quartz glass substrate prepared by setting it on the same tray is attached. A substrate (dummy substrate) was used. The transmittance and retardation of the thin film 30 for pattern formation were measured by taking out the substrate (dummy substrate) with the thin film 30 for pattern formation from the chamber before forming the etching mask film 40 . Table 2 shows the measurement results.

<Measurement of composition of thin film 30 for pattern formation>

For the thin film 30 for pattern formation of the photomask blank 10 of Examples and Comparative Examples, compositional analysis in the depth direction by X-ray photoelectron spectroscopy (XPS) was performed. For the actual measurement, a dummy substrate was used similarly to the measurement of the transmittance.

In the composition analysis result in the depth direction by XPS for the photomask blank 10, the thin film 30 for pattern formation is a composition gradient region at the interface between the transparent substrate 20 and the thin film 30 for pattern formation, and Except for the composition gradient region at the interface between the thin film 30 for pattern formation and the etching mask film 40, the content rate of each constituent element was substantially constant toward the depth direction. Table 2 shows the measurement results of the film composition (atomic %). In addition, the reason why oxygen is contained in the thin film 30 for pattern formation is considered because a trace amount of oxygen existed in the chamber at the time of film-forming.

<Measurement of membrane structure>

In the position of the center of the transfer pattern formation area of the photomask blank 10 of an Example and a comparative example, cross-sectional SEM (scanning electron microscope) observation was performed at a magnification of 80000 times. For actual observation, a dummy substrate was used similarly to the measurement of transmittance. Table 2 shows the observation results. In the "film structure" column of Table 2, what is described as "columnar" shows that the thin film 30 for pattern formation has a columnar structure by cross-sectional SEM observation of the thin film 30 for pattern formation. That is, in the Examples and Comparative Examples described as "columnar", the particles of the compound constituting the thin film for pattern formation 30 have a columnar particle structure that grows toward the thickness direction of the thin film 30 for pattern formation. It means that what you have is confirmed. In particular, in Examples 1, 2 and 3, in the grain structure of the columnar phase of the thin film 30 for pattern formation, the columnar grains in the film thickness direction are irregularly formed, and the length of the columnar grains in the film thickness direction is also It was confirmed that it was in an uneven state. Moreover, in these Examples, it was also confirmed that the small part of the thin film 30 for pattern formation is continuously formed in the film thickness direction.

<Measurement of spatial frequency spectrum>

With respect to the images of Examples and Comparative Examples obtained by cross-sectional SEM observation at a magnification of 80000 as described above, the region including the central portion in the thickness direction of the thin film 30 for pattern formation is 64 pixels long × 256 pixels wide. It was extracted as image data of a pixel. For example, Fig. 5A shows image data of 64 pixels in length x 256 pixels in width in the first embodiment. Fig. 5C is a diagram in which symbols indicating the x-direction and the y-direction are attached to Fig. 5A. The vertical direction indicated by "y" in FIG. 5C is the thickness direction of the cross section of the thin film 30 for pattern formation, and the lateral direction indicated by "x" is the thin film 30 for pattern formation formed on the transparent substrate 20 . In the cross-sectional view of , the direction parallel to the boundary line between the transparent substrate 20 and the thin film 30 for pattern formation. In the images of FIGS. 5A and 5C , a larger image data value is displayed in white, and a smaller image data value is displayed in black. Further, Fourier transform was performed on the image data shown in Fig. 5A. For example, Fig. 5B shows a result of Fourier transform on the image data of 64 pixels in length x 256 pixels in width in the first embodiment. Fig. 5D is a diagram in which symbols indicating the X direction and the Y direction are attached to Fig. 5B. In addition, in the Fourier transform image of FIG. 5D, the dashed-dotted line indicated by "X" is a horizontal line passing through the origin with the center of the image as the origin. A pixel of the image of FIG. 5D on the dashed-dotted line is a spatial frequency component in the horizontal direction, and corresponds to a spatial frequency component in the horizontal direction indicated by "x" in FIG. 5C. In Figs. 5B and 5D, the signal intensity of the spatial frequency component subjected to the Fourier transform is shown by the contrast of each pixel. In the images of FIGS. 5B and 5D , the larger the value of the signal strength is, the whiter it is, and the smaller the value of the signal strength is, the darker it is. 5B and 5D are shown so that the spatial frequency of the center of the image is the lowest and the spatial frequency of both ends of the image is the highest, according to a conventional method of Fourier transform of two-dimensional image data. 5B and 5D, the highest spatial frequency (spatial frequency at both ends) when Fourier-transformed image data of 64 pixels vertically x 256 pixels horizontally is shown as a ratio of spatial frequencies, have. The same is true for the longitudinal direction of FIGS. 5B and 5D . In addition, in Fig. 5E, in the Fourier transform images of Figs. 5B and 5D, the center of the image is taken as the origin, and on a horizontal line passing through the origin (a dashed-dotted line shown as "X" in Fig. 5D) The relationship between the ratio of the spatial frequency and the signal intensity corresponding to the spatial frequency is shown. That is, the horizontal axis of Fig. 5E is the ratio of spatial frequencies corresponding to the horizontal direction indicated by the cross section "x" of the thin film 30 for pattern formation shown in Figs. 5A and 5B, and the vertical axis of Fig. 5E is the spatial frequency. is the corresponding signal strength. In addition, a graph in which the horizontal axis and the vertical axis are enlarged with the origin of FIG. 5E as the center is shown in FIG. 5F .

For example, in Example 1, in the spatial frequency spectrum distribution obtained by the Fourier transform, the signal intensity (maximum signal intensity) at the origin of the spatial frequency is 3100000, and apart from the maximum signal intensity, the signal intensity of 45746 is It was confirmed that the spatial frequency spectrum with In Example 1, 45746/3100000 = 0.015 (that is, 1.5%) with respect to the maximum signal intensity corresponding to the origin of the spatial frequency, and the thin film 30 for pattern formation had a columnar structure having a signal intensity of 0.8% or more. In this way, with respect to the images obtained by scanning electron microscope observation of the cross-section of the photomask blank 10 of Examples and Comparative Examples at a magnification of 80000 times, the region including the central portion in the thickness direction of the thin film 30 for pattern formation. In the spatial frequency spectrum distribution obtained by extracting as image data of 64 pixels in length x 256 pixels in width and Fourier transforming the image data, it has a signal intensity of 0.8% or more with respect to the maximum signal intensity corresponding to the origin of the spatial frequency. When a spatial frequency spectrum existed, it described as "presence" in the column of "presence or absence of a spatial frequency spectrum having a predetermined signal intensity" of Table 2.

In addition, Table 2 shows to what extent a signal having a signal strength of 0.8% or more with respect to the maximum signal strength corresponding to the origin of the spatial frequency is located at a spatial frequency away from the origin of the spatial frequency. The value shown in the "distance from the origin of the spatial frequency of a given signal" column of Table 2 is 100% of the maximum spatial frequency (that is, the maximum spatial frequency corresponding to both ends of 256 pixels on the horizontal axis), and a spatial frequency separated to a certain extent. is expressed as a percentage. For example, with respect to the Fourier transform image of Example 1 as shown in Fig. 5B, the spatial frequency origin, that is, the center of the image in Fig. 5B as the origin (0), corresponds to both ends of 256 pixels on the horizontal axis. Assuming that the maximum spatial frequency is 1 (100%), a signal having a signal strength of 1.5% (a spatial frequency signal having a signal strength of 45746 described above) with respect to the maximum signal strength corresponding to the origin of the spatial frequency is the origin It was a thin film 30 for pattern formation having a columnar structure having a signal at a position 0.086, that is, 8.6% away from it.

Fig. 6A shows image data of 64 pixels in length x 256 pixels in width of Comparative Example 4. As shown in Figs. As in the case of Example 1, image data that is a result of Fourier transform on the image data shown in Fig. 6A is shown in Fig. 6B. Fig. 6C shows a graph of the relationship between the spatial frequency and the signal strength derived from the Fourier transform image of Fig. 6B in the same procedure as in the case of the first embodiment. FIG. 6D shows graphs in which the horizontal and vertical axes are enlarged with the origin of FIG. 6C as the center. In addition, in the same procedure as in the case of Example 1, a graph of the relationship between spatial frequency and signal strength derived from each image data of 64 pixels in length x 256 pixels in width cut out from each cross-sectional SEM of Examples 2 and 3 7 and 8 are enlarged views of . In addition, also in each image, such as a Fourier transform of another Example and a comparative example which are not shown here, it created by the same procedure. In the same procedure as in Example 1, for each of Examples 2 and 3 and Comparative Examples 1 to 5, "the presence or absence of a spatial frequency spectrum having a predetermined signal intensity" and "the origin of the spatial frequency of the predetermined signal" Distance from" is shown in Table 2.

<Photomask 100 and its manufacturing method>

A photomask 100 was manufactured using the photomask blank 10 of Examples and Comparative Examples prepared as described above. In actuality, the photomask blank 10 was formed by forming the etching mask film 40 on the above-described dummy substrate. On the etching mask film 40 of the photomask blank 10, a photoresist film was applied using a resist coating device.

Thereafter, a photoresist film was formed through a heating/cooling process.

Then, the photoresist film was drawn using the laser drawing apparatus, and the resist film pattern which is a hole pattern with a hole diameter of 1.5 micrometers was formed on the etching mask film 40 through a developing and rinsing process.

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

Then, using the first etching mask film pattern 40a as a mask, the thin film 30 for pattern formation is wet-etched with a molybdenum silicide etchant obtained by diluting a mixture of ammonium hydrogen fluoride and hydrogen peroxide with pure water. A pattern 30a was formed. This wet etching was performed with an overetching time of 110% in order to verticalize the cross-sectional shape and to form a required fine pattern.

For example, Example 1 having a transmittance of 50% with respect to light having a wavelength of 405 nm has no significant difference in silicon content from Comparative Example 1 having a transmittance of 40%. However, the etching rate in Example 1 became 122% with respect to the etching rate in Comparative Example 1 mentioned later, and was able to shorten etching time.

Thereafter, the resist film pattern was peeled off.

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

Thereafter, a photoresist film was formed through a heating/cooling process.

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

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

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

In this way, on the transparent substrate 20, the thin film pattern 30a for pattern formation, the thin film pattern 30a for pattern formation, and the etching mask film pattern 40b having a hole diameter of 1.5 mu m in the transfer pattern formation region. Photomasks 100 of Examples and Comparative Examples in which a light-shielding band having a laminated structure of were formed were obtained.

<Cross-sectional shape of the photomask 100>

The cross section of the obtained photomask 100 was observed with a scanning electron microscope. 9 to 12, the cross-sectional shapes of Example 1 and Comparative Examples 1, 4 and 5 are shown. In addition, Examples 2 and 3 are results equivalent to Example 1, and illustration is abbreviate|omitted. In addition, since Comparative Examples 2 and 3 had the same result as Comparative Example 1, these also abbreviate|omit illustration. The cross section of the thin film pattern 30a for pattern formation is an upper surface (a surface in contact with a transparent substrate and an opposite surface), a lower surface (a surface in contact with the transparent substrate) and a side surface (connecting the upper surface and the lower surface) of the thin film pattern 30a for pattern formation. side) is composed of. The angle of the cross section of the thin film pattern 30a for pattern formation is, when viewed in cross section, the contact point between the upper surface and the side surface of the thin film pattern 30a for pattern formation is referred to as contact A, and the contact point between the side surface and the lower surface is referred to as contact point B. , refers to the angle between the straight line connecting the contact A and the contact B and the main surface of the transparent substrate. In the "Cross-sectional shape (angle)" column of Table 2, the angle of the cross section of the thin film pattern 30a for pattern formation of the photomask 100 of an Example and a comparative example is shown. It can be said that the cross-sectional shape is favorable, so that the angle of a cross section is close to 90 degrees.

The thin film patterns 30a for pattern formation of the photomasks 100 of Examples 1 to 3 had a cross-sectional shape close to vertical. Therefore, the thin film pattern 30a for pattern formation formed in the photomask 100 of Examples 1-3 had the cross-sectional shape which can fully exhibit a phase shift effect. On the other hand, Comparative Examples 1-4 had a smaller cross-sectional angle than Examples 1-3, and were inferior to the cross-sectional shape. 12, in Comparative Example 5 containing 8% oxygen (O), in the vicinity of the boundary between the side surface of the thin film pattern 30a for pattern formation and the main surface of the transparent substrate, a necessary pattern formation use Since the notch of the thin film pattern 30a was made at the time of wet etching, the angle of the cross section comparable with the Example and other comparative examples could not be measured.

The thin film 30 for pattern formation of Examples 1 to 3 has a columnar structure. Specifically, from the observation result of the cross-sectional SEM photograph, the thin films 30 for pattern formation of Examples 1 to 3 had a columnar grain structure (columnar structure), and columnar grains growing in the film thickness direction were irregularly formed. has been In addition, from the observation result of the cross-sectional SEM photograph (for example, FIG. 5A of Example 1), the thin film 30 for pattern formation of Examples 1 to 3 has a relatively high density of each columnar particle portion, and It is formed from small parts with low density. It is considered that the thin film patterns 30a for pattern formation of Examples 1 to 3 having such a columnar grain structure have a favorable cross-sectional shape by wet etching according to the following mechanism.

That is, when the thin film 30 for pattern formation is patterned by wet etching, etching becomes easy to advance in the film thickness direction because etching liquid permeates in the small part in the thin film 30 for pattern formation. On the other hand, columnar particles are irregularly formed in a direction perpendicular to the film thickness direction (a direction parallel to the main surface of the transparent substrate), and small portions in this direction are formed intermittently. Therefore, it is difficult for etching to proceed in a direction perpendicular to the film thickness direction, and side etching is suppressed. When the thin film 30 for pattern formation of Examples 1 to 3 has a columnar grain structure (columnar structure) by the above mechanism, in the thin film pattern 30a for pattern formation, a good cross-sectional shape close to vertical I think this has been obtained. The cross-sectional angle of Comparative Example 4 (the titanium silicide-based pattern formation thin film as in Examples 1 to 3) having no columnar structure was significantly lowered compared to that of Examples 1 to 3, and the columnar structure was good. It is clear that it contributes to the formation of the cross-sectional shape.

In addition, in the thin film pattern 30a for pattern formation of Examples 1 to 3, no permeation was seen in any of the interface with the etching mask film pattern and the interface with the transparent substrate, and no damage to the surface of the transparent substrate was observed. . Therefore, in exposure light containing light in a wavelength range of 313 nm or more and 436 nm or less, more specifically, in exposure light of composite light containing at least one of i-line, h-line, and g-line, a photo having an excellent phase shift effect A mask 100 was obtained.

In view of the above, when the photomasks 100 of Examples 1 to 3 are set on a mask stage of an exposure apparatus and exposed and transferred to a resist film on a substrate for a display apparatus, a transfer containing a fine pattern of less than 2.0 µm is used. It can be said that the pattern can be transferred with high precision.

<Light resistance and chemical resistance>

A sample in which the thin film 30 for pattern formation used in the photomask blanks 10 of Examples 1 to 3 and Comparative Examples 1 to 5 was formed on the transparent substrate 20 was prepared. The thin film 30 for pattern formation of the samples of Examples 1 to 3 and Comparative Examples 1 to 5 was irradiated with ultraviolet light so that the total irradiation amount was 10 kJ/cm 2 by a metal halide light source containing ultraviolet light having a wavelength of 300 nm or more. The light resistance of the thin film 30 for pattern formation was evaluated by measuring the transmittance before and after irradiation with a predetermined ultraviolet light, and calculating the change in transmittance [(transmittance before ultraviolet irradiation)-(transmittance after ultraviolet irradiation)]. The transmittance was measured using a spectrophotometer.

In Example 1, the change of the transmittance|permeability before and behind ultraviolet irradiation was favorable at 0.3 % (0.3 point), and Examples 2 and 3 were also the same result. In addition, as in Examples 1 to 3, Comparative Examples 4 and 5 having a titanium silicide-based thin film for pattern formation were also relatively good. On the other hand, in Comparative Example 1 having a molybdenum silicide-based thin film for pattern formation, the change in transmittance before and after ultraviolet irradiation was 0.9% (0.9 points), and Comparative Example 1 was inferior to Examples 1 to 3. In addition, Comparative Examples 2 and 3 were similarly inferior to Examples 1-3. From the above, it turned out that the thin film for pattern formation of Examples 1-3 is an excellent film|membrane with high light resistance.

The sample in which the thin film 30 for pattern formation used in the photomask blank 10 of Example 1 and Comparative Example 1 was formed on the transparent substrate 20 was prepared. For the thin film 30 for pattern formation of the samples of Example 1 and Comparative Example 1, SPM cleaning with a mixed solution of sulfuric acid and hydrogen peroxide (cleaning time: 5 minutes), and SC- with a mixed solution of ammonia, hydrogen peroxide and water The washing test of 5 cycles was performed by making 1 washing|cleaning (washing time: 5 minutes) into 1 cycle, and the chemical resistance of the thin film 30 for pattern formation was evaluated.

The tolerance of the thin film 30 for pattern formation is measured by measuring the reflectance spectrum in a wavelength range of 200 nm to 500 nm before and after performing the cleaning test, and the wavelength corresponding to the lowest reflectance at which the reflectance becomes convex downward (bottom peak wavelength) was evaluated by the amount of change in

As a result of the chemical resistance evaluation, in Example 1 having the titanium silicide-based thin film for pattern formation, the amount of change in the bottom peak wavelength per cleaning cycle was as small as 0.4 nm, and the chemical resistance was good. On the other hand, in Comparative Example 1 having a molybdenum silicide-based thin film for pattern formation, the amount of change in the bottom peak wavelength per cleaning cycle was as large as 1.0 nm, and the chemical resistance was inferior to that of Example 1.

As described above, the thin film 30 for pattern formation of Example 1 having high light resistance also has high chemical resistance, and thus the titanium silicide-based thin film for pattern formation of Examples 2 to 3 and Comparative Examples 4 to 5 is also a thin film having high chemical resistance. It is thought that On the other hand, the thin film 30 for pattern formation of Comparative Example 1 having low light resistance also has low chemical resistance. Therefore, it is thought that the thin film for pattern formation of the molybdenum silicide type|system|group of Comparative Examples 2-3 is also a thin film with low chemical resistance similarly to the comparative example 1.

<LER (line edge roughness)>

The smaller the value of LER, the smoother the shape of the edge when the thin film for pattern formation is viewed from the top is closer to a linear shape. That is, it is so preferable that LER is small. LER was evaluated as follows.

First, each of the photomasks 100 of Examples 1 to 3 and Comparative Examples 1 to 5 was subjected to a scanning electron microscope from the upper surface (the surface in contact with the transparent substrate 20 and the opposite surface) side of the thin film for pattern formation. was observed, and an image including the edge of the thin film for pattern formation was acquired at a magnification of 12000 times. From this image, the LER was measured using PMSite, a measurement software for MASK MVM-SEM E3620 (registered trademark) by Advanced Test Co., Ltd.

Regarding the LERs of Comparative Examples 1 to 3, Comparative Example 1 (transmittance 40%) was 67.9 nm, Comparative Example 2 (transmittance 29%) was 36.0 nm, and Comparative Example 3 (transmittance 21%) was 31.6 nm, and the transmittance was It turned out that LER deteriorated, so that it was high (there was much silicon content). In contrast, the LER of Example 1 (50% transmittance) is 29.0 nm, the LER of Example 2 (33% transmittance) is 17.7 nm, and the LER of Example 3 (23% transmittance) is 30.1 nm. It didn't get any worse. In addition, in the comparison of Example 1 and Comparative Example 1, the comparison of Example 2 and Comparative Example 2, and the comparison of Example 3 and Comparative Example 3, Examples 1 to 3 showed superior LER than Comparative Examples 1 to 3 It turned out that the shape of an edge was smoother and was close|similar to a linear shape.

Comparative Examples 1 to 3 (molybdenum silicide-based) had an increased silicon content in order to obtain a relatively high transmittance, and had a columnar structure in order to suppress a decrease in the etching rate due to the high silicon content. According to the studies of the present inventors, Examples 1 to 3 (titanium silicide type) easily form a columnar structure, and even if the vacuum degree at the time of film formation was high, it was able to be set as a favorable columnar structure. On the other hand, Comparative Examples 1-3 had a columnar structure when sputtering gas pressure was made higher (0.8 Pa or more) than Examples 1-3. For this reason, in Comparative Examples 1-3, the amount of oxygen in the sputtering chamber at the time of film-forming becomes larger than an Example, and, thereby, the thin film for pattern formation of Comparative Examples 1-3 contains more oxygen than Examples 1-3. Therefore, it is considered that the LER of Comparative Examples 1 to 3 deteriorated as a result. Moreover, Comparative Example 4 had a good LER as in the Example, but as described above, since the cross-sectional shape was inferior to that of the Example, it was insufficient as a photomask used for high-precision pattern transfer. In Comparative Example 5, compared with Examples 1 to 3, the LER was inferior and the cross-sectional shape was deteriorated, so that it was insufficient as a photomask used for high-precision pattern transfer.

<Measurement A of etching rate>

As the etching solution A, an etching solution containing ammonium hydrogen fluoride, hydrogen peroxide, and water was prepared. Specifically, etching liquid A is an etching liquid containing 0.1 to 0.8 weight% of ammonium hydrogenfluoride, 0.5 to 4.0 weight% of hydrogen peroxide, and water. Using the etching liquid A, the thin films 30 for pattern formation of Examples 1-3 and Comparative Examples 1-5 were etched, and the etching rate was measured. In the "etch rate A" column of Table 2, the etching rate (unit: nm/min) of the thin film 30 for pattern formation of Examples 1-3 and Comparative Examples 1-5 by etching liquid A is shown.

From the results shown in Table 2, it can be understood that the etching rate by the etching solution A in Example 1 (transmittance 50%) is larger than the etching rate in Comparative Example 1 (transmittance 40%) and Comparative Example 4 (transmittance 42%). . Although the etching rate by the etching liquid A of Example 2 (transmittance 33%) was smaller than the etching rate of the comparative example 2 (transmittance 29%), it was a sufficient value in manufacture of a photomask. Moreover, it is understood that the etching rate by the etching liquid A of Example 3 (transmittance 23%) is larger than the etching rate of the comparative example 3 (transmittance 21%). Further, in Comparative Example 5, a large etching rate was obtained, but as shown in Fig. 12, in the vicinity of the boundary between the side surface of the thin film pattern 30a for pattern formation and the main surface of the transparent substrate, necessary pattern formation The notch of the thin film pattern 30a arose, and the phase shift effect was not fully exhibited. Therefore, it can be said that the photomask 100 of Examples 1-3 has a favorable cross-sectional shape, and compared with the photomask 100 of Comparative Examples 1-5, the etching rate is substantially improved.

As described above, the thin films for pattern formation of Examples 1 to 3 have all of high light resistance (chemical resistance), high etching rate, good cross-sectional shape, and LER while satisfying desired optical properties (transmittance, phase difference). It became clear that it was excellent.

In addition, in the above-mentioned embodiment, although the example of the photomask 100 for display apparatus manufacture and the photomask blank 10 for manufacturing the photomask 100 for display apparatus manufacture was demonstrated, it is not limited to this. The photomask blank 10 and/or the photomask 100 of the present invention can also be applied to semiconductor device manufacturing, MEMS manufacturing, printed circuit board manufacturing, and the like. Moreover, also in the binary photomask blank which has a light-shielding film as the thin film 30 for pattern formation, and the binary mask which has a light-shielding film pattern, it is possible to apply this invention.

In addition, although the above-mentioned embodiment demonstrated the example in which the size of the transparent substrate 20 is 1214 size (1220 mm x 1400 mm x 13 mm), it is not limited to this. In the case of the photomask blank 10 for manufacturing a display device, a large size transparent substrate 20 is used, and the size of the transparent substrate 20 is 300 mm or more in one side of the main surface. The size of the transparent substrate 20 used for the photomask blank 10 for display apparatus manufacture is 330 mm x 450 mm or more and 2280 mm x 3130 mm or less, for example.

In addition, in the case of the photomask blank 10 for semiconductor device manufacturing, MEMS manufacturing, and printed circuit board manufacturing, a small transparent substrate 20 is used, and the size of the transparent substrate 20 is the length of one side. is less than 9 inches. The size of the transparent substrate 20 used for the photomask blank 10 of the said use is 63.1 mm x 63.1 mm or more and 228.6 mm x 228.6 mm or less, for example. Usually, as the transparent substrate 20 for the photomask 100 for semiconductor device manufacture and MEMS manufacture, a size 6025 (152 mm x 152 mm) or a size 5009 (126.6 mm x 126.6 mm) is used. In addition, normally as the transparent substrate 20 for the photomask 100 for printed circuit board manufacture, 7012 size (177.4 mm x 177.4 mm) or 9012 size (228.6 mm x 228.6 mm) is used.

10: photomask blank
20: transparent substrate
30: thin film for pattern formation
30a: thin film pattern for pattern formation
40: etching mask film
40a: first etching mask film pattern
40b: second etching mask film pattern
50: first resist film pattern
60: second resist film pattern
100: photo mask

Claims (10)

A photomask blank for manufacturing a display device having a thin film for pattern formation on a transparent substrate, comprising:
The thin film for pattern formation is made of a material containing titanium (Ti), silicon (Si), and nitrogen (N),
The thin film for pattern formation has a columnar structure,
A photomask blank for manufacturing a display device, characterized in that the content of oxygen included in the pattern formation is 7 atomic% or less. According to claim 1, wherein the thin film for pattern formation, the cross section of the photomask blank with respect to an image obtained by scanning electron microscopy at a magnification of 80,000 times, including a central portion in the thickness direction of the thin film for pattern formation In the spatial frequency spectrum distribution obtained by extracting as image data of 64 vertical pixels x 256 horizontal pixels for the region and Fourier transforming the image data, signal intensity of 0.8% or more with respect to the maximum signal intensity corresponding to the origin of the spatial frequency A photomask blank for manufacturing a display device, characterized in that a spatial frequency spectrum having a The pattern formation thin film according to claim 1 or 2, wherein the signal having a signal strength of 0.8% or more is at a spatial frequency separated from the origin of the spatial frequency by 6.7% or more when the maximum spatial frequency is 100%. A photomask blank for manufacturing a display device, characterized in that. The phase shift film according to claim 1 or 2, wherein the thin film for pattern formation has optical characteristics with transmittances of 1% or more and 80% or less and a phase difference of 160° or more and 200° or less with respect to a representative wavelength of exposure light. A photomask blank for manufacturing a display device, characterized in that The photomask blank for manufacturing a display device according to claim 1 or 2, wherein an etching mask film having different etching selectivity with respect to the pattern forming thin film is provided on the pattern forming thin film. The photomask blank for manufacturing a display device according to claim 5, wherein the etching mask film is made of a material containing chromium and substantially not containing silicon. A step of preparing a photomask blank for manufacturing a display device according to claim 1 or 2;
forming a resist film on the thin film for pattern formation, and wet etching the thin film for pattern formation using the resist film pattern formed with the resist film as a mask to form a transfer pattern on the transparent substrate; A method of manufacturing a photomask for manufacturing a display device, characterized in that. A step of preparing a photomask blank for manufacturing a display device according to claim 5;
forming a resist film on the etching mask film, wet etching the etching mask film using the resist film pattern formed with the resist film as a mask to form an etching mask film pattern on the pattern forming thin film;
and forming a transfer pattern on the transparent substrate by wet-etching the pattern-forming thin film using the etching mask film pattern as a mask. The photomask for manufacturing a display device obtained by the manufacturing method of the photomask for manufacturing a display device of Claim 7 is mounted on the mask stage of an exposure apparatus, and the said transfer pattern formed on the said photomask for display device manufacturing is applied to the display device. A method of manufacturing a display device, comprising an exposure step of exposing and transferring a resist formed on a substrate. The photomask for display device manufacture obtained by the manufacturing method of the photomask for display device manufacture of Claim 8 is mounted on the mask stage of an exposure apparatus, and the said transfer pattern formed on the said photomask for display device manufacture is applied to the display apparatus. A method of manufacturing a display device, comprising an exposure step of exposing and transferring a resist formed on a substrate.

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