JP7204979B2 - Photomask blank, photomask manufacturing method, and display device manufacturing method - Google Patents

Description

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

2. Description of the Related Art In recent years, display devices such as FPDs (Flat Panel Displays) typified by LCDs (Liquid Crystal Displays) are rapidly increasing in screen size and viewing angle, as well as high definition and high speed display. One of the factors required for achieving high-definition and high-speed display is the fabrication of electronic circuit patterns such as fine elements and wiring with high dimensional accuracy. Photolithography is often used for patterning electronic circuits for display devices. Therefore, there is a need for photomasks such as phase shift masks and binary masks for manufacturing display devices on which fine and highly accurate patterns are formed.

For example, Patent Document 1 discloses a phase-shifting mask blank having a phase-shifting film on a transparent substrate. In this mask blank, the phase shift film has a reflectance of 35% or less and a reflectance of 1% to 40% for compound wavelength exposure light including i-line (365 nm), h-line (405 nm), and g-line (436 nm). A metal silicide compound containing at least one light element substance of oxygen (O), nitrogen (N), and carbon (C) so as to have a transmittance and sharply slope the pattern section when forming the pattern. The metal silicide compound is formed by injecting the reactive gas containing the light element substance and the inert gas at a ratio of 0.5:9.5 to 4:6. ing.
Further, Patent Document 2 discloses a transparent substrate, a light semi-transmissive film having a property of changing the phase of exposure light and made of a metal silicide-based material, and an etching mask film made of a chromium-based material. A phase shift mask blank is disclosed. In this phase shift mask blank, a composition gradient region is formed at the interface between the light semitransmissive film and the etching mask film. In the compositionally graded region, the ratio of the component that slows down the wet etching rate of the light semitransmissive film increases in the depth direction. The oxygen content in the composition gradient region is 10 atomic % or less.

Korea Registered Patent No. 1801101 Patent No. 6101646

As a phase shift mask used in recent high-definition (1000 ppi or more) panel production, a phase shift mask with a hole diameter of 6 μm or less and a line There is a demand for a phase shift mask on which a fine phase shift film pattern with a width of 4 μm or less is formed. Specifically, there is a demand for a phase shift mask in which a fine phase shift film pattern with a hole diameter of 1.5 μm is formed.
In order to realize pattern transfer with higher resolution, a phase shift mask blank having a phase shift film having a transmittance of 15% or more to exposure light and a phase shift film pattern having a transmittance of 15% or more to exposure light are used. Formed phase shift masks are needed. Regarding the cleaning resistance (chemical properties) of the phase shift mask blank and the phase shift mask, the phase shift film and the phase shift film pattern have a cleaning resistance that suppresses changes in optical properties due to film reduction and surface composition changes. A phase shift mask blank having a phase shift film formed thereon and a phase shift mask having a wash-resistant phase shift film pattern formed thereon are desired.
In order to meet the requirements for transmittance to exposure light and cleaning resistance, it is effective to increase the ratio of silicon in the atomic ratio of metal and silicon in the metal silicide compound (metal silicide-based material) that constitutes the phase shift film. However, the wet etching rate is significantly slowed (wet etching time is long), and the substrate is damaged by the wet etching solution, resulting in a decrease in the transmittance of the transparent substrate.
In a binary mask blank having a light-shielding film containing a transition metal and silicon, when a light-shielding pattern is formed on the light-shielding film by wet etching, there is a demand for washing resistance, and the same problem as above occurs. rice field.

Accordingly, the present invention has been made to solve the above problems, and an object of the present invention is to transfer a pattern onto a pattern-forming thin film such as a phase shift film or a light shielding film containing a transition metal and silicon by wet etching. To provide a photomask blank, a method for manufacturing a photomask blank, a method for manufacturing a photomask, and a method for manufacturing a display device, which can shorten the wet etching time and can form a transfer pattern having a favorable cross-sectional shape. be.

The inventor of the present invention has earnestly studied measures for solving these problems. First, the atomic ratio of the transition metal and silicon in the thin film for pattern formation is a material with a transition metal:silicon ratio of 1:3 or more. A thin film for pattern formation was formed by adjusting the oxygen gas contained in the sputtering gas introduced into the film forming chamber so that the thin film contained a large amount of oxygen (O). As a result, although the wet etching speed for forming the transfer pattern has increased, the phase shift film in the phase shift mask blank has a lower refractive index for the exposure light, so the desired phase difference (for example, 180°) The film thickness required for obtaining the is increased. In addition, in the light-shielding film in the binary mask blank, the extinction coefficient for the exposure light decreases, so the film thickness required to obtain the desired light-shielding performance (for example, optical density (OD) of 3 or more) increases. end up An increase in the film thickness of the pattern-forming thin film is disadvantageous in pattern formation by wet etching, and since the film thickness increases, there is a limit to the effect of shortening the wet etching time. On the other hand, the atomic ratio of the transition metal and silicon (transition metal: silicon = 1:3 or more) described above has advantages such as increased washing resistance of the thin film for pattern formation. It is not preferable to deviate from the composition ratio of the transition metal and silicon described above.

Therefore, the present inventors changed the way of thinking and examined changing the film structure by adjusting the pressure of the sputtering gas in the film forming chamber. When forming a thin film for pattern formation on a substrate, the sputtering gas pressure in the film forming chamber is usually set to 0.1 to 0.5 Pa. However, the inventor purposely set the sputtering gas pressure higher than 0.5 Pa to deposit the thin film for pattern formation. Then, when a pattern-forming thin film is formed at a sputtering gas pressure of 0.8 Pa or more and 3.0 Pa or less, a transfer pattern is formed on the pattern-forming thin film by wet etching after having suitable characteristics as a thin film. In this case, the inventors have found that the etching time can be greatly shortened and a transfer pattern having a favorable cross-sectional shape can be formed. The thin film for pattern formation thus formed had a columnar structure that is not found in ordinary thin films for pattern formation. The present invention was made as a result of the above earnest studies, and has the following configurations.

(Configuration 1) A photomask blank having a thin film for pattern formation on a transparent substrate,
The photomask blank is an original plate for forming a photomask having a transfer pattern on the transparent substrate by wet etching the pattern-forming thin film,
The pattern-forming thin film contains a transition metal and silicon,
A photomask blank, wherein the pattern-forming thin film has a columnar structure.

(Configuration 2) The thin film for pattern formation is
Regarding the image obtained by observing the cross section of the photomask blank at a magnification of 80,000 times with a scanning electron microscope, the area including the central portion in the thickness direction of the pattern-forming thin film is image data of 64 pixels in length × 256 pixels in width. In the spatial frequency spectrum distribution obtained by extracting and Fourier transforming the image data, there is a spatial frequency spectrum having a signal intensity of 1.0% or more with respect to the maximum signal intensity corresponding to the origin of the spatial frequency. The photomask blank of configuration 1, wherein the photomask blank is
(Configuration 3) In the pattern-forming thin film, the signal having a signal intensity of 1.0% or more is at a spatial frequency that is 2.0% or more away from the origin of the spatial frequency when the maximum spatial frequency is 100%. The photomask blank according to Structure 2, characterized by:

(Configuration 4) Any one of Configurations 1 to 3, wherein the atomic ratio of the transition metal and the silicon contained in the pattern-forming thin film is transition metal:silicon = 1:3 or more and 1:15 or less. The photomask blank described in .

(Constitution 5) The photomask blank according to any one of constitutions 1 to 4, wherein the thin film for pattern formation contains at least nitrogen or oxygen.
(Structure 6) The photomask blank according to any one of Structures 1 to 5, wherein the transition metal is molybdenum.

(Arrangement 7) The pattern-forming thin film is a phase shift film having optical characteristics such as a transmittance of 1% or more and 80% or less and a phase difference of 160° or more and 200° or less with respect to a representative wavelength of exposure light. The photomask blank according to any one of configurations 1 to 6, characterized by:

(Structure 8) The photomask blank according to any one of Structures 1 to 7, further comprising an etching mask film having an etching selectivity different from that of the pattern-forming thin film on the pattern-forming thin film. .
(Arrangement 9) The photomask blank according to Arrangement 8, wherein the etching mask film is made of a material containing chromium and substantially free of silicon.

(Arrangement 10) A method for producing a photomask blank, comprising forming a pattern-forming thin film containing a transition metal and silicon on a transparent substrate by a sputtering method, comprising:
The pattern-forming thin film is formed by using a transition metal silicide target containing a transition metal and silicon in a film forming chamber, and forming a sputtering gas pressure in the film forming chamber to which a sputtering gas is supplied at a pressure of 0.8 Pa or more and 3.0 Pa or less. A method for manufacturing a photomask blank, characterized by:

(Structure 11) The method of manufacturing a photomask blank according to structure 10, wherein the atomic ratio of the transition metal and silicon in the transition metal silicide target is transition metal:silicon=1:3 or more and 1:15 or less. .

(Structure 12) Structure 10 or 11, wherein an etching mask film is formed on the pattern-forming thin film by using a sputtering target made of a material having an etching selectivity different from that of the pattern-forming thin film. A method of manufacturing the described photomask blank.
(Structure 13) The method of manufacturing a photomask blank according to structure 12, wherein the thin film for pattern formation and the etching mask film are formed using an in-line sputtering apparatus.

(Structure 14) A step of preparing the photomask blank according to any one of Structures 1 to 7 or the photomask blank manufactured by the method for manufacturing a photomask blank according to Structure 10 or 11;
forming a resist film on the pattern-forming thin film, and wet-etching the pattern-forming thin film using a resist film pattern formed from the resist film as a mask to form a transfer pattern on the transparent substrate; A method of manufacturing a photomask, comprising:

(Structure 15) A step of preparing the photomask blank according to Structure 8 or 9 or the photomask blank manufactured by the method for manufacturing a photomask blank according to Structure 12 or 13;
forming a resist film on the etching mask film, wet-etching the etching mask film using a resist film pattern formed from the resist film as a mask, and forming an etching mask film pattern on the pattern-forming thin film; When,
and wet-etching the pattern-forming thin film using the etching mask film pattern as a mask to form a transfer pattern on the transparent substrate.
(Structure 16) A photomask obtained by the method for manufacturing a photomask according to Structure 14 or 15 is placed on a mask stage of an exposure apparatus, and the transfer pattern formed on the photomask is transferred to a display device substrate. A method of manufacturing a display device, comprising an exposure step of exposing and transferring onto a resist formed thereon.

According to the photomask blank or the method for manufacturing a photomask blank according to the present invention, when forming a required fine transfer pattern by wet etching the transfer pattern thin film, the pattern forming thin film is washed from the viewpoint of washing resistance and the like. Even when a silicon-rich metal silicide compound is used, the transmittance of the transparent substrate does not decrease due to damage to the substrate due to the wet etching solution, and a transfer pattern with a good cross-sectional shape can be obtained in a short etching time. A formable photomask blank can be obtained.

Further, according to the photomask manufacturing method of the present invention, a photomask is manufactured using the photomask blank described above. Therefore, even if the thin film for pattern formation is made of a silicon-rich metal silicide compound from the viewpoint of washing resistance, there is no decrease in transmittance of the transparent substrate caused by damage to the substrate due to the wet etching solution. A photomask having a transfer pattern with good transfer accuracy can be manufactured. This photomask can be applied to miniaturization of line-and-space patterns and contact holes.

Further, according to the display device manufacturing method of the present invention, a display device is manufactured using a photomask manufactured using the above-described photomask blank or a photomask obtained by the above-described photomask manufacturing method. . Therefore, a display device having fine line-and-space patterns and contact holes can be manufactured.

1 is a schematic diagram showing a film configuration of a phase shift mask blank according to Embodiment 1; FIG. FIG. 10 is a schematic diagram showing a film configuration of a phase shift mask blank according to a second embodiment; FIG. 10 is a schematic diagram showing a manufacturing process of a phase shift mask according to a third embodiment; FIG. 11 is a schematic diagram showing a manufacturing process of a phase shift mask according to a fourth embodiment; (a) is an enlarged photograph (image data) of the central portion in the thickness direction of the phase shift film in the cross-sectional SEM image of the phase shift mask blank of Example 1; FIG. 2(b) shows the result of Fourier transform of the enlarged photograph (image data) of FIG. 2(a). 4 is a dark field plane STEM photograph of the phase shift film in the phase shift mask blank of Example 1. FIG. 4 is a cross-sectional photograph of the phase shift mask of Example 1. FIG. 4A is an enlarged photograph (image data) of the central portion in the thickness direction of the phase shift film in the cross-sectional SEM image of the phase shift mask blank of Example 2. FIG. FIG. 2(b) shows the result of Fourier transform of the enlarged photograph (image data) of FIG. 2(a). 4 is a cross-sectional photograph of the phase shift mask of Example 2. FIG. 4A is an enlarged photograph (image data) of the central portion in the thickness direction of the phase shift film in the cross-sectional SEM image of the phase shift mask blank of Example 3. FIG. FIG. 2(b) shows the result of Fourier transform of the enlarged photograph (image data) of FIG. 2(a). 10 is a cross-sectional photograph of the phase shift mask of Example 3. FIG. 4A is an enlarged photograph (image data) of the central portion in the thickness direction of the phase shift film in the cross-sectional SEM image of the phase shift mask blank of Comparative Example 1. FIG. FIG. 2(b) shows the result of Fourier transform of the enlarged photograph (image data) of FIG. 2(a). 4 is a cross-sectional photograph of a phase shift mask of Comparative Example 1. FIG.

Embodiment 1.2.
In Embodiments 1 and 2, phase shift mask blanks will be described. The phase shift mask blank of Embodiment 1 is obtained by wet-etching the phase shift film using an etching mask film pattern in which a desired pattern is formed on the etching mask film as a mask. It is an original plate for forming a mask. Further, the phase shift mask blank of the second embodiment is obtained by wet-etching the phase shift film using a resist film pattern in which a desired pattern is formed on the resist film as a mask. It is an original plate for forming a film.

FIG. 1 is a schematic diagram showing the film structure of a phase shift mask blank 10 according to the first embodiment.
A phase shift mask blank 10 shown in FIG. 1 includes a transparent substrate 20 , a phase shift film 30 formed on the transparent substrate 20 , and an etching mask film 40 formed on the phase shift film 30 .
FIG. 2 is a schematic diagram showing the film structure of the phase shift mask blank 10 according to the second embodiment.
A phase shift mask blank 10 shown in FIG. 2 includes a transparent substrate 20 and a phase shift film 30 formed on the transparent substrate 20 .
The transparent substrate 20, the phase shift film 30 and the etching mask film 40 that constitute the phase shift mask blank 10 of the first and second embodiments will be described below.

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

The phase shift film 30 is composed of a transition metal silicide material containing a transition metal and silicon. Molybdenum (Mo), tantalum (Ta), tungsten (W), titanium (Ti), zirconium (Zr), and the like are suitable as transition metals, and molybdenum (Mo) is particularly preferred.
Moreover, the phase shift film 30 preferably contains at least nitrogen or oxygen. In the transition metal silicide-based material, oxygen, which is a light element component, has the effect of lowering the extinction coefficient compared to nitrogen, which is also a light element component. (Nitrogen, etc.) can be reduced, and the reflectance of the front and rear surfaces of the phase shift film 30 can also be effectively reduced. In the above transition metal silicide-based material, nitrogen, which is a light element component, has the effect of not lowering the refractive index compared to oxygen, which is also a light element component. It can be made thin. Further, the total content of light element components including oxygen and nitrogen contained in the phase shift film 30 is preferably 40 atomic % or more. More preferably, it is 40 atomic % or more and 70 atomic % or less, and 50 atomic % or more and 65 atomic % or less. Further, when oxygen is contained in the phase shift film 30, the oxygen content is desirably more than 0 atomic % and 40 atomic % or less in terms of defect quality and chemical resistance.
Examples of transition metal silicide-based materials include nitrides of transition metal silicides, oxides of transition metal silicides, oxynitrides of transition metal silicides, and oxynitride carbides of transition metal silicides. In addition, when the transition metal silicide-based material is a molybdenum silicide-based material (MoSi-based material), a zirconium silicide-based material (ZrSi-based material), or a molybdenum zirconium silicide-based material (MoZrSi-based material), an excellent pattern cross section can be obtained by wet etching. A molybdenum silicide-based material (MoSi-based material) is particularly preferable because it is easy to obtain a shape.
In addition to oxygen and nitrogen described above, the phase shift film 30 may contain other light element components such as carbon and helium for the purpose of reducing film stress and controlling the wet etching rate.
The phase shift film 30 has a function of adjusting the reflectance of light incident from the transparent substrate 20 side (hereinafter sometimes referred to as back surface reflectance), and a function of adjusting the transmittance and phase difference of exposure light. have
The phase shift film 30 can be formed by a sputtering method.

This phase shift film 30 has a columnar structure. This columnar structure can be confirmed by cross-sectional SEM observation of the phase shift film 30 . That is, in the columnar structure of the present invention, the particles of the transition metal silicide compound containing the transition metal and silicon forming the phase shift film 30 are directed in the film thickness direction of the phase shift film 30 (the direction in which the particles are deposited). It refers to the state of having a columnar grain structure that extends along the length of the grain. In the present application, particles whose length in the film thickness direction is longer than their length in the vertical direction are defined as columnar particles. In other words, the phase shift film 30 has columnar particles extending in the film thickness direction over the plane of the transparent substrate 20 . In addition, the phase shift film 30 has a sparse portion having a relatively lower density than the columnar particles (hereinafter sometimes simply referred to as “sparse portion”) by adjusting film formation conditions (sputtering pressure, etc.). is also formed. The phase shift film 30 effectively suppresses side etching during wet etching and further improves the cross-sectional shape of the pattern. It is preferable that the elongated columnar particles are formed irregularly in the film thickness direction. More preferably, the columnar particles of the phase shift film 30 are in a state in which the length in the film thickness direction is uneven. The sparse portions of the phase shift film 30 are preferably formed continuously in the film thickness direction. Moreover, it is preferable that the sparse portions of the phase shift film 30 are intermittently formed in the direction perpendicular to the film thickness direction. A preferred form of the columnar structure of the phase shift film 30 can be expressed as follows using indices obtained by Fourier transforming the image obtained by the cross-sectional SEM observation. That is, the columnar structure of the phase shift film 30 is obtained by observing the cross section of the phase shift mask blank at a magnification of 80000 times with a cross-sectional SEM. The spatial frequency spectrum obtained by Fourier transforming the extracted image data of pixels x 256 horizontal pixels has a signal intensity of 1.0% or more with respect to the maximum signal intensity corresponding to the origin of the spatial frequency. state is preferred. By forming the phase shift film 30 into the columnar structure described above, the wet etching solution can easily permeate the phase shift film 30 in the film thickness direction during wet etching using a wet etching solution. It is faster, and the wet etching time can be greatly shortened. Therefore, even if the phase shift film 30 is a silicon-rich metal silicide compound, the transmittance of the transparent substrate does not decrease due to the damage to the substrate caused by the wet etching solution. In addition, since the phase shift film 30 has a columnar structure extending in the film thickness direction, side etching during wet etching is suppressed, so that the cross-sectional shape of the pattern is improved.

In addition, the phase shift film 30 has a spatial frequency of 100% when a signal having an intensity signal of 1.0% or more with respect to the maximum signal intensity of the spatial frequency spectrum distribution obtained by Fourier transform has a maximum spatial frequency of 100%. It is preferably at a spatial frequency that is 2.0% or more away from the origin. The fact that signals having an intensity signal of 1.0% or more with respect to the maximum signal intensity are separated by 2.0% or more means that a spatial frequency component higher than a certain level is included. That is, the phase shift film 30 has a fine columnar structure. This is preferable because it reduces line edge roughness.

The atomic ratio of the transition metal and silicon contained in the phase shift film 30 is preferably transition metal:silicon=1:3 or more and 1:15 or less. Within this range, the effect of suppressing a drop in the wet etching rate during pattern formation of the phase shift film 30 by the columnar structure can be enhanced. Moreover, the washing resistance of the phase shift film 30 can be improved, and the transmittance can be easily increased. From the viewpoint of enhancing the washing resistance of the phase shift film 30, the atomic ratio of the transition metal and silicon contained in the phase shift film 30 is transition metal: silicon = 1:4 or more and 1:15 or less, more preferably transition metal: It is desirable that the silicon ratio is 1:5 or more and 1:15 or less.

The transmittance of the phase shift film 30 with respect to exposure light satisfies the required value for the phase shift film 30 . The transmittance of the phase shift film 30 is preferably 1% or more and 80% or less, more preferably 15% or more and 65%, with respect to light of a predetermined wavelength (hereinafter referred to as representative wavelength) contained in the exposure light. % or less, more preferably 20% or more and 60% or less. That is, when the exposure light is compound light including light in the wavelength range of 313 nm or more and 436 nm or less, the phase shift film 30 has the above-described transmittance with respect to the light of the representative wavelengths included in the wavelength range. For example, when the exposure light is compound light including i-line, h-line and g-line, phase shift film 30 has the above-described transmittance for any one of i-line, h-line and g-line.
The transmittance can be measured using a phase shift amount measuring device or the like.

The phase difference of the phase shift film 30 with respect to exposure light satisfies the value required for the phase shift film 30 . The phase difference of the phase shift film 30 is preferably 160° or more and 200° or less, more preferably 170° or more and 190° or less with respect to the light of the representative wavelength included in the exposure light. Due to this property, the phase of the light of the representative wavelength contained in the exposure light can be changed from 160° to 200°. Therefore, a phase difference of 160° or more and 200° or less is generated between the light of the representative wavelength transmitted through the phase shift film 30 and the light of the representative wavelength transmitted only through the transparent substrate 20 . That is, when the exposure light is compound light including light in the wavelength range of 313 nm to 436 nm, the phase shift film 30 has the above-described phase difference with respect to the light of the representative wavelength included in the wavelength range. For example, when the exposure light is compound light including i-line, h-line and g-line, phase shift film 30 has the above-described phase difference with respect to any one of i-line, h-line and g-line.
The phase difference can be measured using a phase shift amount measuring device or the like.

The back surface reflectance of the phase shift film 30 is 15% or less, preferably 10% or less, in the wavelength range of 365 nm to 436 nm. Further, when the exposure light includes the j-line, the back surface reflectance of the phase shift film 30 is preferably 20% or less, more preferably 17% or less, with respect to light in the wavelength range from 313 nm to 436 nm. More preferably, it should be 15% or less. Further, the back surface reflectance of the phase shift film 30 is preferably 0.2% or more in the wavelength range of 365 nm to 436 nm, and preferably 0.2% or more for light in the wavelength range of 313 nm to 436 nm.
The back surface reflectance can be measured using a spectrophotometer or the like.

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

The etching mask film 40 is arranged on the upper side of the phase shift film 30 and is made of a material having etching resistance to the etchant used to etch the phase shift film 30 (etching selectivity different from that of the phase shift film 30). The etching mask film 40 may have a function of blocking transmission of the exposure light, and the film surface reflectance of the phase shift film 30 with respect to light incident from the phase shift film 30 side is 350 nm to 436 nm. It may have a function of reducing the film surface reflectance to 15% or less in the wavelength range. The etching mask film 40 is made of a chromium-based material containing chromium (Cr). More specifically, the chromium-based material is chromium (Cr), or a material containing chromium (Cr) and at least one of oxygen (O), nitrogen (N), and carbon (C). is mentioned. Alternatively, a material containing chromium (Cr) and at least one of oxygen (O), nitrogen (N), and carbon (C), and further containing fluorine (F) can be used. For example, materials forming the etching mask film 40 include Cr, CrO, CrN, CrF, CrCO, CrCN, CrON, CrCON, and CrCONF.
The etching mask film 40 can be formed by a sputtering method.

In the case where the etching mask film 40 has a function of blocking the transmission of exposure light, the optical density with respect to the exposure light in the portion where the phase shift film 30 and the etching mask film 40 are laminated is preferably 3 or more, and more preferably: 3.5 or more, more preferably 4 or more.
Optical density can be measured using a spectrophotometer, an OD meter, or the like.

The etching mask film 40 may be composed of a single film having a uniform composition according to its function, may be composed of a plurality of films having different compositions, or may be composed of different compositions in the thickness direction. It may be composed of a single continuously changing film.

It should be noted that the phase shift mask blank 10 shown in FIG. The present invention can also be applied to a phase shift mask blank comprising

Next, a method of manufacturing the phase shift mask blank 10 of the first and second embodiments will be described. The phase shift mask blank 10 shown in FIG. 1 is manufactured by performing the following phase shift film forming process and etching mask film forming process. The phase shift mask blank 10 shown in FIG. 2 is manufactured by a phase shift film formation process.
Each step will be described in detail below.

1. Phase Shift Film Forming Step First, the transparent substrate 20 is prepared. The transparent substrate 20 is made of any glass material, such as synthetic quartz glass, quartz glass, aluminosilicate glass, soda lime glass, low thermal expansion glass (SiO ₂ —TiO ₂ glass, etc.), as long as it is transparent to exposure light. It may be

Next, a phase shift film 30 is formed on the transparent substrate 20 by sputtering.
The phase shift film 30 is deposited using a transition metal silicide target containing a transition metal and silicon, which are the main components of the material constituting the phase shift film 30, or a transition metal silicide target containing a transition metal, silicon, oxygen and/or nitrogen. is used as a sputtering target, for example, a sputtering gas atmosphere consisting of an inert gas containing at least one selected from the group consisting of helium gas, neon gas, argon gas, krypton gas and xenon gas, or the inert gas, The sputtering is performed in a sputtering gas atmosphere consisting of a mixed gas with an active gas containing at least oxygen and nitrogen selected from the group consisting of oxygen gas, nitrogen gas, carbon dioxide gas, nitrogen monoxide gas and nitrogen dioxide gas. The phase shift film 30 is formed at a gas pressure of 0.8 Pa or more and 3.0 Pa or less in the film forming chamber during sputtering. By setting the gas pressure range in this manner, a columnar structure can be formed in the phase shift film 30 . This columnar structure can suppress side etching during pattern formation, which will be described later, and achieve a high etching rate. Here, the atomic ratio of the transition metal and silicon in the transition metal silicide target is transition metal:silicon = 1:3 or more and 1:15 or less. This is preferable in that the washing resistance of the phase shift film 30 can be improved and the transmittance can be easily increased.

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

When the phase shift film 30 is composed of a single film, the film forming process described above is performed only once by appropriately adjusting the composition and flow rate of the sputtering gas. When the phase shift film 30 is composed of a plurality of films with different compositions, the film formation process described above is performed a plurality of times while appropriately adjusting the composition and flow rate of the sputtering gas. The phase shift film 30 may be deposited using targets having different content ratios of the elements constituting the sputtering target. When the film formation process is performed multiple times, the sputtering power applied to the sputtering target may be changed for each film formation process.

2. Surface Treatment Process The phase shift film 30 is treated with oxygen such as a transition metal silicide oxide containing a transition metal, silicon and oxygen, or a transition metal silicide oxynitride containing a transition metal, silicon, oxygen and nitrogen. When the phase shift film 30 is made of a transition metal silicide material containing You may make it perform the surface treatment process which carries out. When the phase shift film 30 is composed of a transition metal, silicon, and a nitrogen-containing transition metal silicide nitride, the transition metal oxide content is higher than that of the oxygen-containing transition metal silicide material. is small. Therefore, when the material of the phase shift film 30 is a transition metal silicide nitride, the surface treatment process may or may not be performed.
Examples of the surface treatment process for adjusting the state of surface oxidation of the phase shift film 30 include a method of surface treatment with an acidic aqueous solution, a method of surface treatment with an alkaline aqueous solution, and a method of dry treatment such as ashing. .
Thus, the phase shift mask blank 10 of Embodiment 2 is obtained. To manufacture the phase shift mask blank 10 of Embodiment 1, the following etching mask film formation step is further performed.

3. Etching Mask Film Forming Step After the phase shift film forming step, a surface treatment for adjusting the state of surface oxidation of the surface of the phase shift film 30 is performed as necessary, and then the phase shift film is formed by sputtering. An etching mask film 40 is formed on 30 . The etching mask film 40 is preferably formed using an in-line sputtering device. When the sputtering apparatus is an in-line sputtering apparatus, the thickness of the etching mask film 40 can also be controlled by the transport speed of the transparent substrate 20 .
The etching mask film 40 is formed using a sputtering target containing chromium or a chromium compound (chromium oxide, chromium nitride, chromium carbide, chromium oxynitride, chromium carbide oxynitride, etc.), for example, helium gas, neon gas, argon. A sputtering gas atmosphere consisting of an inert gas containing at least one selected from the group consisting of gas, krypton gas and xenon gas, or at least one selected from the group consisting of helium gas, neon gas, argon gas, krypton gas and xenon gas. and an active gas containing at least one selected from the group consisting of oxygen gas, nitrogen gas, nitrogen monoxide gas, nitrogen dioxide gas, carbon dioxide gas, hydrocarbon-based gas, and fluorine-based gas It is carried out in a sputter gas atmosphere of Hydrocarbon gases include, for example, methane gas, butane gas, propane gas, and styrene gas. By adjusting the gas pressure in the film forming chamber during sputtering, the etching mask film 40 can be formed into a columnar structure like the phase shift film 30 . As a result, side etching during pattern formation, which will be described later, can be suppressed, and a high etching rate can be achieved.

When the etching mask film 40 is composed of a single film with a uniform composition, the above-described film formation process is performed only once without changing the composition and flow rate of the sputtering gas. When the etching mask film 40 is composed of a plurality of films with different compositions, the film formation process described above is performed a plurality of times while changing the composition and flow rate of the sputtering gas for each film formation process. When the etching mask film 40 is composed of a single film whose composition changes continuously in the thickness direction, the film formation process described above is repeated while changing the composition and flow rate of the sputtering gas with the elapsed time of the film formation process. do it only once.
Thus, the phase shift mask blank 10 of Embodiment 1 is obtained.

Since the phase shift mask blank 10 shown in FIG. 1 has the etching mask film 40 on the phase shift film 30, an etching mask film forming process is performed when manufacturing the phase shift mask blank 10. FIG. Further, when manufacturing a phase shift mask blank having an etching mask film 40 on the phase shift film 30 and a resist film on the etching mask film 40, after the etching mask film forming process, a resist film is formed on the etching mask film 40. to form When manufacturing a phase shift mask blank having a resist film on the phase shift film 30 in the phase shift mask blank 10 shown in FIG. 2, the resist film is formed after the phase shift film forming step.

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

In the phase shift mask blank 10 of Embodiments 1 and 2, when the phase shift film 30 is patterned by wet etching, etching in the film thickness direction is promoted while side etching is suppressed. A phase shift film pattern having good and desired transmittance (for example, high transmittance) can be formed in a short etching time. Therefore, it is possible to manufacture a phase shift mask capable of accurately transferring a high-definition phase shift film pattern without lowering the transmittance of the transparent substrate due to damage to the substrate by the wet etching solution. A mask blank is obtained.

Embodiment 3.4.
In Embodiments 3 and 4, a method for manufacturing a phase shift mask will be described.

FIG. 3 is a schematic diagram showing a method of manufacturing a phase shift mask according to the third embodiment. FIG. 4 is a schematic diagram showing a method of manufacturing a phase shift mask according to the fourth embodiment.
The method of manufacturing a phase shift mask shown in FIG. 3 is a method of manufacturing a phase shift mask using the phase shift mask blank 10 shown in FIG. and writing and developing a desired pattern on the resist film to form a resist film pattern 50 (first resist film pattern forming step), and using the resist film pattern 50 as an etching mask a step of wet-etching the film 40 to form an etching mask film pattern 40a on the phase shift film 30 (first etching mask film pattern forming step); 30 is wet-etched to form a phase shift film pattern 30a on the transparent substrate 20 (phase shift film pattern forming step). The method further includes a second resist film pattern forming step and a second etching mask film pattern forming step.

The method of manufacturing a phase shift mask shown in FIG. 4 is a method of manufacturing a phase shift mask using the phase shift mask blank 10 shown in FIG. Then, a desired pattern is drawn and developed on the resist film to form a resist film pattern 50 (first resist film pattern forming step), and the phase shift film 30 is wetted using the resist film pattern 50 as a mask. and a step of etching to form a phase shift film pattern 30a on the transparent substrate 20 (phase shift film pattern forming step).
Each step of the manufacturing process of the phase shift mask according to the third and fourth embodiments will be described in detail below.

Manufacturing process of the phase shift mask according to the third embodiment 1. First Resist Film Pattern Forming Step In the first resist film pattern forming step, first, a resist film is formed on the etching mask film 40 of the phase shift mask blank 10 of the first embodiment. The resist film material to be used is not particularly limited. For example, any material may be used as long as it is sensitive to laser light having a wavelength selected from the wavelength range of 350 nm to 436 nm, which will be described later. Moreover, the resist film may be either positive type or negative type.
After that, a desired pattern is drawn on the resist film using a laser beam having a wavelength selected from a wavelength range of 350 nm to 436 nm. The pattern drawn on the resist film is the pattern formed on the phase shift film 30 . Patterns drawn on the resist film include line-and-space patterns and hole patterns.
Thereafter, the resist film is developed with a predetermined developer to form a first resist film pattern 50 on the etching mask film 40 as shown in FIG. 3(a).

2. First Etching Mask Film Pattern Forming Step In the first etching mask film pattern forming step, first, the etching mask film 40 is etched using the first resist film pattern 50 as a mask to form a first etching mask film pattern 40a. to form The etching mask film 40 is made of a chromium-based material containing chromium (Cr). When the etching mask film 40 has a columnar structure, the etching rate is high and side etching can be suppressed, which is preferable. The etchant for etching the etching mask film 40 is not particularly limited as long as it can selectively etch the etching mask film 40 . Specifically, an etchant containing ceric ammonium nitrate and perchloric acid is mentioned.
Thereafter, the first resist film pattern 50 is removed using a resist remover or by ashing as shown in FIG. 3(b). In some cases, the next phase shift film pattern forming step may be performed without removing the first resist film pattern 50 .

3. Phase Shift Film Pattern Forming Step In the first phase shift film pattern forming step, the phase shift film 30 is wet-etched using the first etching mask film pattern 40a as a mask, and as shown in FIG. A phase shift film pattern 30a is formed. The phase shift film pattern 30a includes a line-and-space pattern and a hole pattern. The etchant for etching the phase shift film 30 is not particularly limited as long as it can selectively etch the phase shift film 30 . For example, an etchant containing ammonium fluoride, phosphoric acid and hydrogen peroxide, and an etchant containing ammonium hydrogen fluoride and hydrogen peroxide can be used.
In order to improve the cross-sectional shape of the phase shift film pattern 30a, the wet etching is performed for a time (overetching time) longer than the time (just etching time) until the transparent substrate 20 is exposed in the phase shift film pattern 30a. is preferred. Considering the influence on the transparent substrate 20, etc., the overetching time is preferably within the time obtained by adding 20% of the just etching time to the just etching time, and is 10% of the just etching time. It is more preferable to be within the time period added with

4. Second Resist Film Pattern Forming Step In the second resist film pattern forming step, first, a resist film is formed to cover the first etching mask film pattern 40a. The resist film material to be used is not particularly limited. For example, any material may be used as long as it is sensitive to laser light having a wavelength selected from the wavelength range of 350 nm to 436 nm, which will be described later. Moreover, the resist film may be either positive type or negative type.
After that, a desired pattern is drawn on the resist film using a laser beam having a wavelength selected from a wavelength range of 350 nm to 436 nm. The pattern to be drawn on the resist film includes a light shielding band pattern for shielding the peripheral region of the region where the pattern is formed on the phase shift film 30, a light shielding band pattern for shielding the central portion of the phase shift film pattern, and the like. Depending on the transmittance of the phase shift film 30 with respect to the exposure light, the pattern drawn on the resist film may be a pattern without a light shielding band pattern for shielding the central portion of the phase shift film pattern 30a.
Thereafter, the resist film is developed with a predetermined developer to form a second resist film pattern 60 on the first etching mask film pattern 40a, as shown in FIG. 3(d).

5. Second etching mask film pattern forming process In the second etching mask film pattern forming process, the first etching mask film pattern 40a is etched using the second resist film pattern 60 as a mask, and the pattern shown in FIG. As shown, a second etch mask film pattern 40b is formed. The first etching mask film pattern 40a is formed of a chromium-based material containing chromium (Cr). The etchant for etching the first etching mask film pattern 40a is not particularly limited as long as it can selectively etch the first etching mask film pattern 40a. For example, an etchant containing ceric ammonium nitrate and perchloric acid may be used.
After that, the second resist film pattern 60 is stripped using a resist stripper or by ashing.
Thus, a phase shift mask 100 is obtained.
In the above description, the case where the etching mask film 40 has the function of blocking the transmission of the exposure light has been described, but the case where the etching mask film 40 simply has the function of a hard mask when the phase shift film 30 is etched. In the above description, the second resist film pattern forming step and the second etching mask film pattern forming step are not performed, and the first etching mask film pattern is removed after the phase shift film pattern forming step. , to fabricate the phase shift mask 100 .

According to the phase shift mask manufacturing method of the third embodiment, since the phase shift mask blank of the first embodiment is used, the etching time can be shortened, and a phase shift film pattern having a favorable cross-sectional shape can be formed. . Therefore, it is possible to manufacture a phase shift mask capable of accurately transferring a fine phase shift film pattern. A phase shift mask manufactured in this manner can be applied to miniaturization of line-and-space patterns and contact holes.

Manufacturing process of the phase shift mask according to the fourth embodiment 1. Resist Film Pattern Forming Step In the resist film pattern forming step, first, a resist film is formed on the phase shift film 30 of the phase shift mask blank 10 of the second embodiment. The resist film materials used are the same as those described in the third embodiment. In addition, before forming the resist film, the phase shift film 30 may be subjected to a surface modification treatment in order to improve the adhesion to the phase shift film 30, if necessary. After forming a resist film in the same manner as described above, a desired pattern is drawn on the resist film using a laser beam having a wavelength selected from the wavelength range of 350 nm to 436 nm. Thereafter, the resist film is developed with a predetermined developer to form a resist film pattern 50 on the phase shift film 30 as shown in FIG. 4(a).
2. Phase Shift Film Pattern Forming Step In the phase shift film pattern forming step, the phase shift film 30 is etched using the resist film pattern as a mask to form a phase shift film pattern 30a as shown in FIG. 4(b). The etchant and overetching time for etching the phase shift film pattern 30a and the phase shift film 30 are the same as those described in the third embodiment.
Thereafter, the resist film pattern 50 is removed using a resist remover or by ashing (FIG. 4(c)).
Thus, a phase shift mask 100 is obtained.
According to the phase shift mask manufacturing method of the fourth embodiment, since the phase shift mask blank of the second embodiment is used, there is no decrease in transmittance of the transparent substrate caused by damage to the substrate due to the wet etching solution. , the etching time can be shortened, and a phase shift film pattern having a good cross-sectional shape can be formed. Therefore, it is possible to manufacture a phase shift mask capable of accurately transferring a fine phase shift film pattern. A phase shift mask manufactured in this manner can be applied to miniaturization of line-and-space patterns and contact holes.

Embodiment 5.
In Embodiment 5, a method for manufacturing a display device will be described. The display device uses the phase shift mask 100 manufactured using the phase shift mask blank 10 described above, or uses the phase shift mask 100 manufactured by the manufacturing method of the phase shift mask 100 described above (mask mounting process). ) and a step of exposing and transferring a transfer pattern onto a resist film on the display device (exposure step).
Each step will be described in detail below.

1. Mounting Step In the mounting step, the phase shift mask manufactured in Embodiment 3 is mounted on the mask stage of the exposure apparatus. Here, the phase shift mask is arranged so as to face the resist film formed on the display device substrate via the projection optical system of the exposure device.

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

According to the manufacturing method of the display device of the third embodiment, it is possible to manufacture a high-definition display device having high resolution and fine line-and-space patterns and contact holes.
In the above embodiments, a phase shift mask blank having a phase shift mask film and a phase shift mask having a phase shift mask film pattern are used as the photomask blank having the pattern forming thin film and the photomask having the transfer pattern. Although the case where it is used has been described, it is not limited to this. For example, the present invention can be applied to a binary mask blank having a light shielding film as a pattern forming thin film or a binary mask having a light shielding film pattern.

Example 1.
A. Phase Shift Mask Blank and Manufacturing Method Thereof To manufacture the phase shift mask blank of Example 1, first, a 1214 size (1220 mm×1400 mm) synthetic quartz glass substrate was prepared as the transparent substrate 20 .

After that, the synthetic quartz glass substrate was placed on a tray (not shown) with the main surface facing downward, and carried into the chamber of an in-line sputtering apparatus.
In order to form the phase shift film 30 on the main surface of the transparent substrate 20, first, argon (Ar) gas and nitrogen (N ₂ ) gas are mixed with the sputtering gas pressure in the first chamber at 1.6 Pa. , an inert gas composed of helium (He) gas (Ar: 18 sccm, N ₂ : 13 sccm, He: 50 sccm) was introduced. Then, a first sputtering target containing molybdenum and silicon (molybdenum:silicon=1:9) is applied with a sputtering power of 7.6 kW to form molybdenum, silicon and nitrogen on the main surface of the transparent substrate 20 by reactive sputtering. A nitride of molybdenum silicide containing was deposited. Then, a phase shift film 30 having a film thickness of 150 nm was formed.

Next, the transparent substrate 20 with the phase shift film 30 is carried into the second chamber, and mixed gas of argon (Ar) gas and nitrogen (N ₂ ) gas (Ar: 65 sccm, N ₂ : 15 sccm) was introduced. Then, a sputtering power of 1.5 kW was applied to the second sputtering target made of chromium to form chromium nitride (CrN) containing chromium and nitrogen on the phase shift film 30 by reactive sputtering (film thickness 15 nm). Next, a mixed gas (30 sccm) of argon (Ar) gas and methane (CH ₄ : 4.9%) gas is introduced while the inside of the third chamber is kept at a predetermined degree of vacuum, and a third sputtering made of chromium is introduced. A sputtering power of 8.5 kW was applied to the target to form chromium carbide (CrC) containing chromium and carbon on CrN by reactive sputtering (thickness: 60 nm). Finally, while the fourth chamber was kept at a predetermined degree of vacuum, mixed gas of argon (Ar) gas and methane (CH ₄ : 5.5%) gas, nitrogen (N ₂ ) gas, and oxygen (O ₂ ) gas were mixed. A mixed gas (Ar + CH ₄ : 30 sccm, N ₂ : 8 sccm, O ₂ : 3 sccm) was introduced, and a sputtering power of 2.0 kW was applied to the fourth sputtering target made of chromium, and reactive sputtering was performed on CrC. A chromium carbooxynitride (CrCON) containing chromium, carbon, oxygen and nitrogen was formed on the substrate (thickness: 30 nm). As described above, the etching mask film 40 having the laminated structure of the CrN layer, the CrC layer and the CrCON layer was formed on the phase shift film 30 .
In this manner, a phase shift mask blank 10 having the phase shift film 30 and the etching mask film 40 formed on the transparent substrate 20 was obtained.

The transmittance and phase difference of the phase shift film 30 of the obtained phase shift mask blank 10 (the surface of the phase shift film 30 was measured using MPM-100 manufactured by Lasertec Co., Ltd.). For the measurement, a substrate with a phase shift film (dummy substrate) was used, which was prepared by setting the phase shift film 30 on the main surface of a synthetic quartz glass substrate, which was set on the same tray. A substrate with a phase shift film (dummy substrate) was taken out from the chamber and measured for the transmittance and phase difference before forming the etching mask film 40. As a result, the transmittance was 27% (wavelength: 405 nm) and the phase difference was 178° (wavelength: 405 nm).

Further, the obtained phase shift mask blank 10 was subjected to composition analysis in the depth direction by X-ray photoelectron spectroscopy (XPS).
In the composition analysis results in the depth direction by XPS for the phase shift mask blank 10, the phase shift film 30 has a composition gradient region at the interface between the transparent substrate 20 and the phase shift film 30, and the phase shift film 30 and the etching mask film 40. The content of each constituent element is almost constant in the depth direction except for the composition gradient region at the interface with the It was 4 atomic %. Also, the atomic ratio of molybdenum and silicon was 1:5, which was in the range of 1:3 or more and 1:15 or less. Also, the total content of oxygen and nitrogen, which are light elements, was 52 atomic %, which was within the range of 50 atomic % or more and 65 atomic % or less. The reason why the phase shift film 30 contains oxygen is considered to be that the sputtering gas pressure was as high as 0.8 Pa or more and a very small amount of oxygen was present in the chamber during film formation.

Next, a cross-sectional SEM (scanning electron microscope) observation was performed at a magnification of 80000 times at the central position of the transfer pattern formation region of the obtained phase shift mask blank 10. As a result, the phase shift film 30 had a columnar structure. I was able to confirm that. That is, it was confirmed that the molybdenum silicide compound particles forming the phase shift film 30 had a columnar grain structure extending in the film thickness direction of the phase shift film 30 . In the columnar grain structure of the phase shift film 30, it was confirmed that the columnar grains in the film thickness direction were formed irregularly, and the lengths of the columnar grains in the film thickness direction were also irregular. . It was also confirmed that the sparse portions of the phase shift film 30 were formed continuously in the film thickness direction. Further, from the image obtained by this cross-sectional SEM observation, the region including the central portion in the thickness direction of the phase shift film 30 was extracted as image data of 64 pixels long×256 pixels wide (FIG. 5A). Further, Fourier transform was performed on the image data shown in FIG. 5 (FIG. 5(b)). In the spatial frequency spectrum distribution obtained by Fourier transform, the signal strength at the origin of the spatial frequency (maximum signal strength) is 3136000, and apart from the maximum signal strength, there is a spatial frequency spectrum having a signal strength of 66150. It was confirmed. This is 66150/3136000=0.021 (that is, 2.1%) with respect to the maximum signal intensity corresponding to the origin of the spatial frequency, and the phase shift film 30 has a columnar shape having a signal intensity of 1.0% or more. was the structure.

5(b), the origin of the spatial frequency, i.e., the center of the image in FIG. is 1 (100%), a signal with a signal strength of 2.1% with respect to the maximum signal strength corresponding to the origin of the spatial frequency is 0.055, that is, 5.5% away from the origin. It was the phase shift film 30 having a columnar structure with a signal at the opposite position. The same applies to Fourier-transformed images of the following examples and comparative examples.
In addition, a plate-like sample of 100 nm in the direction perpendicular to the film thickness direction (the in-plane direction of the substrate) was sampled near the center of the film thickness of the phase shift film 30, and dark-field planar STEM observation was performed. FIG. 6 shows the results of dark-field plane STEM (scanning transmission electron microscope) observation. As shown in FIG. 6, grayish-white and grayish-black mottled patterns thought to be columnar particle portions (grayish-white portions) and between particles (gray-black portions) were observed. Elements (Mo, Si, N, O) constituting the phase shift film 30 were quantitatively analyzed by EDX analysis (energy dispersive X-ray analysis) for the grayish white and grayish black portions (not shown). As a result, the detection amount (count number) of Si is higher than that of Mo in the gray-black portion and the gray-white portion, and the detection amount (count number) of the constituent elements of the phase shift film 30 in the gray-black portion is higher than that of the gray-white portion. It was confirmed that the detected amount (count number) of the constituent elements of the phase shift film 30 in the portion was low. In particular, the amount of Si detected (number of counts) in the gray-black portion is 600 (counts), and the amount of Si detected (number of counts) in the gray-white portion is 400 (counts), compared to other elements. The difference in the detected amount (count number) was large. From this result, it was confirmed that the phase shift film 30 has a relatively high-density particle portion (gray-white portion) and a relatively low-density sparse portion (gray-black portion). . This particle portion corresponds to the columnar particles shown in FIGS. The film density of the entire phase shift film 30 is lower than that of the conventional phase shift film.

B. Phase shift mask and its manufacturing method In order to manufacture the phase shift mask 100 using the phase shift mask blank 10 manufactured as described above, first, on the etching mask film 40 of the phase shift mask blank 10, a resist coating apparatus is applied. was used to apply a photoresist film.
Thereafter, a photoresist film having a film thickness of 520 nm was formed through heating and cooling steps.
After that, a photoresist film was drawn using a laser drawing device, and a resist film pattern of a hole pattern with a hole diameter of 1.5 μm was formed on the etching mask film through development and rinsing steps.

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

After that, using the first etching mask film pattern 40a as a mask, the phase shift film 30 is wet-etched with a molybdenum silicide etchant obtained by diluting a mixed solution of ammonium hydrogen fluoride and hydrogen peroxide with pure water. A film pattern 30a was formed. This wet etching was performed with an over-etching time of 110% in order to make the cross-sectional shape vertical and to form the required fine pattern. The just etching time in Example 1 was 0.15 times as long as the just etching time in Comparative Example described later, and the etching time could be significantly shortened.
After that, the resist film pattern was peeled off.

After that, using a resist coating device, a photoresist film was coated so as to cover the first etching mask film pattern 40a.
Thereafter, a photoresist film having a film thickness of 520 nm was formed through heating and cooling steps.
After that, a photoresist film was drawn using a laser drawing device, and a second resist film pattern 60 for forming a light shielding band was formed on the first etching mask film pattern 40a through development and rinsing processes. .

Thereafter, using the second resist film pattern 60 as a mask, the first etching mask film pattern 40a formed in the transfer pattern forming region is wet-etched with a chromium etchant containing ceric ammonium nitrate and perchloric acid. bottom.
After that, the second resist film pattern 60 is removed.

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

A cross section of the obtained phase shift mask was observed with a scanning electron microscope. The cross section of the phase shift film pattern is composed of the top surface, the bottom surface and the side surfaces of the phase shift film pattern. The angle of the cross section of the phase shift film pattern refers to the angle between the portion (upper side) where the upper surface and the side surface of the phase shift film pattern contact and the portion (lower side) where the side surface and the lower surface contact. The cross-sectional angle of the phase shift film pattern 30a of the obtained phase shift mask was 74°, and the cross-sectional shape was nearly vertical. The phase shift film pattern 30a formed on the phase shift mask of Example 1 had a cross-sectional shape capable of sufficiently exhibiting the phase shift effect. The reason why the phase shift film pattern 30a has a favorable cross-sectional shape due to the columnar structure of the phase shift film 30 is considered to be due to the following mechanism. From the observation result of the cross-sectional SEM photograph of FIG. 7, the phase shift film 30 has a columnar grain structure (columnar structure), and the columnar grains extending in the film thickness direction are irregularly formed. Further, from the observation results of the dark-field planar STEM photograph in FIG. 6 and the observation results of the cross-sectional SEM photograph in FIG. It is formed with sparse parts. From these facts, when the phase shift film 30 is patterned by wet etching, the etchant permeates the sparse portions of the phase shift film 30, which facilitates etching in the film thickness direction. In the direction perpendicular to the surface of the substrate (the direction within the substrate surface), columnar particles are irregularly formed, and the sparse portions in this direction are intermittently formed, so etching in this direction is difficult to proceed. It is considered that the phase shift film pattern 30a has a favorable cross-sectional shape that is nearly vertical because the side etching is suppressed by this. In addition, in the phase shift film pattern, penetration was not observed either at the interface with the etching mask film pattern or at the interface with the substrate. Therefore, a phase shift mask having an excellent phase shift effect in exposure light including light in the wavelength range of 300 nm or more and 500 nm or less, more specifically exposure light of compound light including i-line, h-line and g-line is provided. Got.
Therefore, when the phase shift mask of Example 1 is set on the mask stage of the exposure apparatus and is exposed and transferred to the resist film on the display device, it can be said that a fine pattern of less than 2.0 μm can be transferred with high accuracy. .

The cross-sectional SEM photograph of FIG. 7 is obtained by wet etching (110% etching) of the phase shift film 30 with a molybdenum silicide etchant using the first etching mask film pattern 40a as a mask in the manufacturing process of the phase shift mask of Example 1. is over-etched) to form a phase shift film pattern 30a, and a cross-sectional SEM photograph after peeling off the resist film pattern. As shown in FIG. 7, the phase shift film pattern 30a maintains the columnar structure of the phase shift film 30, and the exposed surface of the transparent substrate 20 after removing the phase shift film 30 is smooth and transparent. The decrease in transmittance due to surface roughness of No. 20 was negligible.

Example 2.
A. Phase Shift Mask Blank and Manufacturing Method Thereof To manufacture the phase shift mask blank of Example 2, as in Example 1, a synthetic quartz glass substrate of 1214 size (1220 mm×1400 mm) was prepared as a transparent substrate.
By the same method as in Example 1, the synthetic quartz glass substrate was carried into the chamber of the in-line type sputtering apparatus. The same sputtering target materials as in Example 1 were used as the first sputtering target, the second sputtering target, the third sputtering target, and the fourth sputtering target. Then, with the sputtering gas pressure in the first chamber set to 1.6 Pa, an inert gas composed of argon (Ar) gas, helium (He) gas, and nitrogen (N ₂ ) gas and a reactive gas are used. A mixed gas (Ar: 18 sccm, N ₂ : 15 sccm, He: 50 sccm, NO: 4 sccm) with a certain nitrogen monoxide gas (NO) was introduced. Then, a first sputtering target containing molybdenum and silicon (molybdenum:silicon=1:9) is applied with a sputtering power of 7.6 kW to deposit molybdenum, silicon and oxygen on the main surface of the transparent substrate 20 by reactive sputtering. and nitrogen-containing molybdenum silicide oxynitrides were deposited. Then, a phase shift film 30 having a film thickness of 140 nm was formed.
After forming the phase shift film on the transparent substrate, the substrate was taken out from the chamber and the surface of the phase shift film was washed with pure water. The pure water cleaning conditions were a temperature of 30 degrees and a cleaning time of 60 seconds.
Thereafter, an etching mask film 40 was formed by the same method as in Example 1. Next, as shown in FIG.
In this manner, a phase shift mask blank 10 having the phase shift film 30 and the etching mask film 40 formed on the transparent substrate 20 was obtained.

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

Further, composition analysis in the depth direction was performed on the obtained phase shift mask blank by X-ray photoelectron spectroscopy (XPS).
As a result, as in Example 1, the phase shift film 30 has a composition gradient region at the interface between the transparent substrate 20 and the phase shift film 30 and a composition gradient region at the interface between the phase shift film 30 and the etching mask film 40. Except for , the content of each constituent element was almost constant in the depth direction, and Mo was 7 atomic %, Si was 38 atomic %, N was 45 atomic %, and O was 10 atomic %. Also, the atomic ratio of molybdenum and silicon was 1:5.4, which was within the range of 1:3 or more and 1:15 or less. In addition, the total content of light elements such as oxygen, nitrogen and carbon was 55 atomic %, which was within the range of 50 atomic % or more and 65 atomic % or less.
Next, cross-sectional SEM observation was performed at a magnification of 80,000 at the central position of the transfer pattern forming region of the obtained phase shift mask blank 10. As a result, it was confirmed that the phase shift film 30 had a columnar structure. did it. That is, it was confirmed that the molybdenum silicide compound particles forming the phase shift film 30 had a columnar grain structure extending in the film thickness direction of the phase shift film 30 . In the columnar grain structure of the phase shift film 30, it was confirmed that the columnar grains in the film thickness direction were formed irregularly, and the lengths of the columnar grains in the film thickness direction were also irregular. . It was also confirmed that the sparse portions of the phase shift film 30 were formed continuously in the film thickness direction. Further, from the image obtained by this cross-sectional SEM observation, the region including the central portion in the thickness direction of the phase shift film 30 was extracted as image data of 64 pixels long×256 pixels wide (FIG. 8A). Further, Fourier transform was performed on the image data shown in FIG. 8(a) (FIG. 8(b)). In the spatial frequency spectrum distribution obtained by Fourier transform, the signal strength (maximum signal strength) at the origin of the spatial frequency is 2406000, and apart from the maximum signal strength, there is a spatial frequency spectrum having a signal strength of 39240. It was confirmed. This is 39240/2406000=0.016 (that is, 1.6%) with respect to the maximum signal intensity corresponding to the origin of the spatial frequency, and the phase shift film 30 has a columnar shape having a signal intensity of 1.0% or more. was the structure.

Also, regarding the Fourier transform image of FIG. 8(b), the origin of the spatial frequency, that is, the center of the image of FIG. Then, a signal with a signal strength of 1.6% with respect to the maximum signal strength corresponding to the origin of the spatial frequency is a fine signal having a signal at a position 0.023, that is, 2.3% away from the origin. The phase shift film 30 had a columnar structure.
Further, in the same manner as in Example 1, near the center of the film thickness of the phase shift film 30, dark-field planar STEM observation was performed. As a result, it was confirmed that the columnar grain portions and the sparse portions were formed in the phase shift film 30 in the same manner as in Example 1. FIG.

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

A cross section of the obtained phase shift mask was observed with a scanning electron microscope. The cross-sectional angle of the phase shift film pattern 30a of the phase shift mask was 74°, and the cross-sectional shape was nearly vertical. In addition, in the phase shift film pattern, penetration was not observed either at the interface with the etching mask film pattern or at the interface with the substrate. Therefore, a phase shift mask having an excellent phase shift effect in exposure light including light in the wavelength range of 300 nm or more and 500 nm or less, more specifically exposure light of compound light including i-line, h-line and g-line is provided. Got.
Therefore, when the phase shift mask of Example 2 is set on the mask stage of the exposure apparatus and is exposed and transferred to the resist film on the display device, it can be said that a fine pattern of less than 2.0 μm can be transferred with high accuracy. .

The cross-sectional SEM photograph of FIG. 9 is obtained by wet etching (110% etching) of the phase shift film 30 with a molybdenum silicide etchant using the first etching mask film pattern 40a as a mask in the manufacturing process of the phase shift mask of Example 2. is over-etched) to form a phase shift film pattern 30a, and a cross-sectional SEM photograph after peeling off the resist film pattern. As shown in FIG. 9, the phase shift film pattern 30a maintains the columnar structure of the phase shift film 30, and the exposed surface of the transparent substrate 20 after removing the phase shift film 30 is smooth and transparent. The decrease in transmittance due to surface roughness of No. 20 was negligible.

Example 3.
A. Phase Shift Mask Blank and Manufacturing Method Thereof The phase shift mask blank of Example 3 is the phase shift mask blank of Example 1 that does not have the etching mask film.
In order to manufacture the phase shift mask blank of Example 3, as in Example 1, a synthetic quartz glass substrate of 1214 size (1220 mm×1400 mm) was prepared as the transparent substrate 20 .
In order to form the phase shift film 30 on the main surface of the transparent substrate 20 using the same film formation method as in Example 1, first, while the sputtering gas pressure in the first chamber was set to 1.4 Pa, argon (Ar) An inert gas (Ar: 18 sccm, N ₂ : 13.5 sccm, He: 50 sccm) composed of nitrogen (N ₂ ) gas and helium (He) gas was introduced. Under these film formation conditions, a phase shift film 30 (thickness: 150 nm) made of molybdenum silicide oxynitride was formed on the transparent substrate 20 .
Thus, a phase shift mask blank 10 having a phase shift film 30 formed on a transparent substrate 20 was obtained.

The transmittance and phase difference of the obtained phase shift film of the phase shift mask blank 10 were measured by MPM-100 manufactured by Lasertech. In order to measure the transmittance and phase difference of the phase shift film, a phase shift film-attached substrate (dummy) was prepared by setting the phase shift film 30 on the main surface of a synthetic quartz glass substrate set in the same tray. substrate) was used. As a result, the transmittance was 24% (wavelength: 405 nm) and the phase difference was 183 degrees (wavelength: 405 nm).

The phase shift film 30 of the obtained phase shift mask blank 10 was subjected to composition analysis in the depth direction by X-ray photoelectron spectroscopy (XPS). The content of each constituent element was almost constant in the longitudinal direction. Also, the atomic ratio of molybdenum and silicon was 1:5, which was in the range of 1:3 or more and 1:15 or less. Also, the total content of the light elements oxygen, nitrogen, and carbon was 52 atomic %, which was within the range of 50 atomic % or more and 65 atomic % or less. In addition, the oxygen content was 0.3 atomic %, which was within the range of more than 0 atomic % and 40 atomic % or less.

Next, cross-sectional SEM observation was performed at a magnification of 80,000 times at the center position of the transfer pattern forming region of the obtained phase shift mask blank 10. As a result, it was found that the phase shift film 30 had a columnar structure. It could be confirmed. That is, it was confirmed that the molybdenum silicide compound particles forming the phase shift film 30 had a columnar grain structure extending in the film thickness direction of the phase shift film 30 . In the columnar grain structure of the phase shift film 30, it was confirmed that the columnar grains in the film thickness direction were formed irregularly, and the lengths of the columnar grains in the film thickness direction were also irregular. . It was also confirmed that the sparse portions of the phase shift film 30 were formed continuously in the film thickness direction. Further, from the image obtained by this cross-sectional SEM observation, the region including the central portion in the thickness direction of the phase shift film 30 was extracted as image data of 64 pixels long×256 pixels wide (FIG. 10(a)). Further, Fourier transform was performed on the image data shown in FIG. 10(a) (FIG. 10(b)). In the spatial frequency spectrum distribution obtained by Fourier transform, the signal strength (maximum signal strength) at the origin of the spatial frequency is 31590000, and apart from the maximum signal strength, there is a spatial frequency spectrum having a signal strength of 47230. It was confirmed. This is 47230/3159000=0.015 (that is, 1.5%) with respect to the maximum signal intensity corresponding to the origin of the spatial frequency, and the phase shift film 30 has a columnar shape having a signal intensity of 1.0% or more. was the structure.

Also, regarding the Fourier transform image of FIG. 10(b), the origin of the spatial frequency, that is, the center of the image of FIG. Then, a signal with a signal strength of 1.5% with respect to the maximum signal strength corresponding to the origin of the spatial frequency has a signal at a position 0.078, that is, 7.8% away from the origin. The phase shift film 30 has a fine columnar structure with a high frequency.
Further, in the same manner as in Example 1, near the center of the film thickness of the phase shift film 30, dark-field planar STEM observation was performed. As a result, it was confirmed that each columnar particle and a sparse portion were formed in the phase shift film 30 in the same manner as in Example 1. FIG.

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

A cross section of the obtained phase shift mask was observed with a scanning electron microscope. The cross-sectional angle of the phase shift film pattern 30a of the phase shift mask was 80°, and the cross-sectional shape was nearly vertical. In addition, in the phase shift film pattern, penetration was not observed either at the interface with the etching mask film pattern or at the interface with the substrate. Therefore, a phase shift mask having an excellent phase shift effect in exposure light including light in the wavelength range of 300 nm or more and 500 nm or less, more specifically exposure light of compound light including i-line, h-line and g-line is provided. Got.
Therefore, when the phase shift mask of Example 3 is set on the mask stage of the exposure apparatus and is exposed and transferred to the resist film on the display device, it can be said that a fine pattern of less than 2.0 μm can be transferred with high accuracy. .

Note that the cross-sectional SEM photograph of FIG. 11 shows that the phase shift film 30 is wet-etched (110%) with a molybdenum silicide etchant using the first etching mask film pattern 40a as a mask in the manufacturing process of the phase shift mask of Example 3. is over-etched) to form a phase shift film pattern 30a, and a cross-sectional SEM photograph after peeling off the resist film pattern. As shown in FIG. 11, the phase shift film pattern 30a maintains the columnar structure of the phase shift film 30, and the exposed surface of the transparent substrate 20 after removing the phase shift film 30 is smooth and transparent. The transmittance due to surface roughness of 20 was negligible. The line edge roughness was even better than in Example 1.

Although molybdenum is used as the transition metal in the above-described embodiments, the same effects as those described above can be obtained with other transition metals.
Moreover, in the above-described embodiments, examples of phase shift mask blanks for manufacturing display devices and phase shift masks for manufacturing display devices have been described, but the present invention is not limited to these. The phase shift mask blank and phase shift mask of the present invention can also be applied to semiconductor device manufacturing, MEMS manufacturing, printed circuit boards, and the like. The present invention can also be applied to a binary mask blank having a light shielding film as a pattern forming thin film or a binary mask having a light shielding film pattern.
Also, in the above embodiment, the size of the transparent substrate is 1214 size (1220 mm×1400 mm×13 mm), but it is not limited to this. In the case of a phase shift mask blank for manufacturing a display device, a large size transparent substrate is used, and the size of the transparent substrate has a side length of 300 mm or more. The size of the transparent substrate used for phase shift mask blanks for manufacturing display devices is, for example, 330 mm×450 mm or more and 2280 mm×3130 mm or less.
In the case of phase shift mask blanks for manufacturing semiconductor devices, MEMS, and printed circuit boards, a small size transparent substrate is used, and the size of the transparent substrate is 9 inches or less on one side. be. The size of the transparent substrate used for the phase shift mask blank for the above application is, for example, 63.1 mm×63.1 mm or more and 228.6 mm×228.6 mm or less. Normally, 6025 size (152 mm x 152 mm) and 5009 size (126.6 mm x 126.6 mm) are used for semiconductor manufacturing and MEMS manufacturing, and 7012 size (177.4 mm x 177.4 mm) is used for printed circuit boards. Alternatively, the 9012 size (228.6 mm×228.6 mm) is used.

Comparative example 1.
A. Phase Shift Mask Blank and Manufacturing Method Thereof To manufacture the phase shift mask blank of Comparative Example 1, a synthetic quartz glass substrate of 1214 size (1220 mm×1400 mm) was prepared as a transparent substrate in the same manner as in Example 1.
By the same method as in Example 1, the synthetic quartz glass substrate was carried into the chamber of the in-line type sputtering apparatus. Then, a mixed gas of argon (Ar) gas and nitrogen (N ₂ ) gas (Ar: 30 sccm, N ₂ : 30 sccm) was introduced while the sputtering gas pressure in the first chamber was set to 0.5 Pa. Then, a first sputtering target containing molybdenum and silicon (molybdenum:silicon=1:9) was applied with a sputtering power of 7.6 kW to form molybdenum, silicon and nitrogen on the main surface of the transparent substrate by reactive sputtering. A nitride containing molybdenum silicide was deposited. Thus, a phase shift film having a thickness of 144 nm was formed.
Thereafter, an etching mask film was formed by the same method as in Example 1.
Thus, a phase shift mask blank was obtained in which the phase shift film and the etching mask film were formed on the transparent substrate.

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

Further, composition analysis in the depth direction was performed on the obtained phase shift mask blank by X-ray photoelectron spectroscopy (XPS). As a result, the phase shift film 30 has a depth direction of , the content of each constituent element was almost constant, and Mo was 8 atomic %, Si was 39 atomic %, N was 52 atomic %, and O was 1 atomic %. Also, the atomic ratio of molybdenum and silicon was 1:4.9, which was within the range of 1:3 or more and 1:15 or less. In addition, the total content of light elements such as oxygen, nitrogen and carbon was 53 atomic %, which was within the range of 50 atomic % or more and 65 atomic % or less.

Next, a cross-sectional SEM observation was performed at a magnification of 80,000 times at the central position of the transfer pattern forming region of the phase shift mask blank 10 obtained. A crystalline structure or an amorphous structure was confirmed. From the image obtained by this cross-sectional SEM observation, the region including the central portion in the thickness direction of the phase shift film 30 was extracted as image data of 64 pixels long×256 pixels wide (FIG. 12(a)). Further, Fourier transform was performed on the image data shown in FIG. 12(a) (FIG. 12(b)). In the spatial frequency spectrum distribution obtained by the Fourier transform, the signal strength (maximum signal strength) at the origin of the spatial frequency is 2073000, and no strong signal other than the maximum strength signal can be confirmed. There was only a frequency spectrum. This is 12600/2073000=0.006 (ie 0.6%) with respect to the maximum signal intensity corresponding to the origin of the spatial frequency, and the phase shift film 30 has a signal intensity of 1.0% or more. It had an ultrafine crystalline structure or an amorphous structure.

B. Phase shift mask and its manufacturing method A phase shift mask was manufactured by the same method as in Example 1 using the phase shift mask blank manufactured as described above. Wet etching of the phase shift film was performed with an over-etching time of 110% in order to make the cross-sectional shape vertical and to form a required fine pattern. The just etching time in Comparative Example 1 was 142 minutes, which was a long time.
The cross-sectional SEM photograph of FIG. 13 shows that in the manufacturing process of the phase shift mask of the comparative example, the phase shift film 30 is wet-etched (110% etch) with a molybdenum silicide etchant using the first etching mask film pattern 40a as a mask. 10 is a cross-sectional SEM photograph before overetching is performed to form a phase shift film pattern 30a and the resist film pattern is peeled off. As shown in FIG. 13, the exposed surface of the transparent substrate 20 after the removal of the phase shift film 30 was rough and clouded visually. Therefore, the decrease in transmittance due to the surface roughness of the transparent substrate 20 was remarkable.
For this reason, when the phase shift mask of Comparative Example 1 is set on the mask stage of an exposure apparatus and is exposed and transferred to a resist film on a display device, it is expected that a fine pattern of less than 2.0 μm cannot be transferred. .

DESCRIPTION OF SYMBOLS 10... Phase shift mask blank, 20... Transparent substrate, 30... Phase shift film,
30a... phase shift film pattern, 40... etching mask film,
40a... First etching mask film pattern,
40b... second etching mask film pattern, 50... first resist film pattern,
60... Second resist film pattern, 100... Phase shift mask

Claims (13)

A photomask blank having a pattern-forming thin film on a transparent substrate,
The pattern-forming thin film contains a transition metal and silicon,
The thin film for pattern formation has a columnar structure,
The columnar structure of the pattern-forming thin film can be determined from an image obtained by observing the cross section of the photomask blank with a scanning electron microscope at a magnification of 80,000 times. In an image of spatial frequency spectrum distribution obtained by extracting image data of 64 pixels by 256 pixels horizontally and further Fourier transforming the image data, the center of the image of the spatial frequency spectrum distribution is defined as the origin of the spatial frequency, A state in which there is a spatial frequency spectrum having a signal intensity of 1.0% or more with respect to the signal intensity corresponding to the origin of the spatial frequency, which is the maximum signal intensity in the image of the spatial frequency spectrum distribution. A photomask blank characterized by: In the columnar structure of the pattern-forming thin film, a horizontal axis is set on the image data, with the origin being 0% and the maximum spatial frequency corresponding to both ends in the direction of 256 pixels in the horizontal direction of the image data being 100%. 2. A state according to claim 1, wherein the signal having a signal strength of 1.0% or more is present at a position on the horizontal axis that is 2.0% or more away from the origin of the spatial frequency. of photomask blanks. 3. The photomask blank according to claim 1, wherein the atomic ratio of the transition metal and the silicon contained in the pattern-forming thin film is transition metal:silicon=1:3 or more and 1:15 or less. . 4. The columnar structure of the pattern-forming thin film according to claim 1, wherein columnar particles extending in the film thickness direction are formed over the surface of the transparent substrate. Photomask blank. 5. A photomask blank according to claim 4, wherein said columnar particles are irregularly formed in a direction perpendicular to a film thickness direction of said pattern forming thin film. 6. The photomask blank according to any one of claims 1 to 5, wherein the pattern-forming thin film contains at least nitrogen or oxygen. 7. The photomask blank according to any one of claims 1 to 6, wherein said transition metal is molybdenum. The thin film for pattern formation is a phase shift film having optical characteristics such as a transmittance of 1% or more and 80% or less and a phase difference of 160° or more and 200° or less with respect to a representative wavelength of exposure light. A photomask blank according to any one of claims 1 to 7. 9. The photomask blank according to any one of claims 1 to 8, further comprising an etching mask film having an etching selectivity different from that of the pattern forming thin film on the pattern forming thin film. 10. The photomask blank of claim 9, wherein said etching mask film comprises a material containing chromium and substantially free of silicon. preparing a photomask blank according to any one of claims 1 to 8;
forming a resist film on the pattern-forming thin film, and wet-etching the pattern-forming thin film using a resist film pattern formed from the resist film as a mask to form a transfer pattern on the transparent substrate; A method of manufacturing a photomask, comprising: preparing a photomask blank according to claim 9 or 10;
forming a resist film on the etching mask film, wet-etching the etching mask film using a resist film pattern formed from the resist film as a mask, and forming an etching mask film pattern on the pattern-forming thin film; When,
and wet-etching the pattern-forming thin film using the etching mask film pattern as a mask to form a transfer pattern on the transparent substrate. A photomask obtained by the method of manufacturing a photomask according to claim 11 or 12 is placed on a mask stage of an exposure apparatus, and the transfer pattern formed on the photomask is formed on a display device substrate. A method of manufacturing a display device, comprising an exposure step of exposing and transferring the resist onto the resist.

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