TWI902765B - Photomask blank, method for manufacturing photomask blank, method for manufacturing photomask, and method for manufacturing display device - Google Patents

Abstract

Provided is a photomask blank in which a transfer pattern having a good cross-sectional shape and satisfying desired cleaning resistance and line edge roughness can be formed, and in which over-etching time can be shortened in forming the transfer pattern in a thin film for pattern formation by wet etching. A photomask blank has a thin film for pattern formation on a transparent substrate. The photomask blank is an original form for forming a photomask having a transfer pattern on a transparent substrate by wet-etching the thin film for pattern formation. The thin film for pattern formation contains a transition metal and silicon. The thin film for pattern formation has a columnar structure and has an upper layer and a lower layer, in which the size of particles forming the columnar structure in the upper layer is less than the size of particles forming the columnar structure in the lower layer.

Description

Photomask substrate, method for manufacturing photomask substrate, method for manufacturing photomask, and method for manufacturing display device.

This invention relates to a photomask substrate, a method for manufacturing the photomask substrate, a method for manufacturing the photomask, and a display device.

In recent years, in display devices such as FPDs (Flat Panel Displays), represented by LCDs (Liquid Crystal Displays), the increasing size of screens, wider viewing angles, and the rapid development of high-precision and high-speed displays have led to advancements. One of the essential elements for these high-precision and high-speed displays is the fabrication of electronic circuit patterns, such as components or wiring, with minute and high dimensional accuracy. The patterning of electronic circuits for these display devices mostly utilizes photolithography. Therefore, masks such as phase-shifting masks or binary masks are needed to form patterns with minute and high precision in the manufacturing of display devices.

For example, Patent Document 1 discloses a phase-reversing photomask substrate having a phase-reversing film disposed on a transparent substrate. In this photomask substrate, the phase-reversing film has a reflectivity of less than 35% and a transmittance of 1% to 40% for exposure light containing a composite wavelength of i-line (365 nm), h-line (405 nm), and g-line (436 nm), and is composed of two or more multilayer films, such that a tilt of the pattern cross-section is rapidly formed during pattern formation. The two or more multilayer films contain a metal silicate compound containing at least one light element substance selected from oxygen (O), nitrogen (N), and carbon (C). The metal silicate compound is formed by injecting a reactive gas containing the above-mentioned light element substance and an inert gas at a ratio of 0.5:9.5 to 4:6. Furthermore, Patent 2 discloses a phase-shifting photomask substrate comprising a transparent substrate, a semi-transparent film containing a silicate-based material that has the property of changing the phase of the exposed light, and an etching mask film containing a chromium-based material. In this phase-shifting photomask substrate, a gradient region is formed at the interface between the semi-transparent film and the etching mask film. In the gradient region, the ratio of components that slow down the wet etching rate of the semi-transparent film increases towards the depth direction. Moreover, the oxygen content in the gradient region is 10 atomic% or less. [Prior Art Documents][Patent Documents]

[Patent Document 1] Korean Patent No. 1801101 [Patent Document 2] Japanese Patent No. 6101646

[Problem Solved by the Invention] As a phase-shifting mask used in recent years to manufacture high-precision (above 1000 ppi) panels, in order to achieve high-resolution pattern transfer, a phase-shifting mask with a micro-phase shifting film pattern having an aperture of less than 6 μm and a linewidth of less than 4 μm is required. Specifically, a phase-shifting mask with a micro-phase shifting film pattern having an aperture of 1.5 μm is required. Furthermore, in order to achieve even higher resolution pattern transfer, a phase-shifting mask substrate having a phase shifting film with a transmittance of more than 15% for the exposed light and a phase-shifting mask having a phase shifting film pattern having a transmittance of more than 15% for the exposed light are required. Furthermore, regarding the washability (chemical properties) of the phase-shifting mask substrate or the phase-shifting mask, it is necessary to form a phase-shifting mask substrate with a washable phase-shifting film and a phase-shifting mask with a washable phase-shifting film pattern. Moreover, the phase-shifting mask substrate and the phase-shifting mask can suppress changes in optical properties caused by the reduction of the phase-shifting film or the phase-shifting film pattern or changes in the surface composition. To meet the requirements for light transmittance and washability during exposure, it is effective to increase the silicon ratio in the atomic ratio of metal to silicon in the metal silicate compound (metal silicate-based material) constituting the phase shift film. However, this results in problems such as a significant decrease in wet etching speed (longer wet etching time) and damage to the substrate by the wet etching solution, leading to a decrease in the transmittance of the transparent substrate. Moreover, when forming a light-shielding pattern on a binary photomask substrate containing a light-shielding film containing a transition metal and silicon by wet etching, washability is also required, presenting the same problems as mentioned above.

Therefore, this invention was made to solve the above-mentioned problems. The purpose of this invention is to provide a photomask substrate, a method for manufacturing the photomask substrate, a method for manufacturing the photomask, and a method for manufacturing a display device. When the photomask substrate is used to form a transfer pattern on 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, the wet etching time can be shortened, and a transfer pattern with a good cross-sectional shape can be formed, satisfying the required washability and edge roughness of the pattern-forming thin film or transfer pattern. [Technical Means for Solving the Problem]

The inventors have focused their research on solutions to these problems. First, a material with an atomic ratio of transition metal to silicon (transition metal:silicon) of 1:3 or higher was selected for the pattern-forming thin film. To shorten the wet etching time of the wet etching solution in the pattern-forming thin film, the oxygen content in the sputtering gas introduced into the film-forming chamber was adjusted to contain more oxygen (O), thus forming the pattern-forming thin film. As a result, the wet etching speed for forming the transfer pattern is increased. However, the refractive index of the exposed light in the phase-shifting film in the phase-shifting photomask substrate decreases, leading to a thicker film thickness required to obtain the desired phase difference (e.g., 180°). Furthermore, in the light-shielding film within the binary photomask substrate, the extinction coefficient for exposed light decreases, resulting in a thicker film required to achieve the desired light-shielding performance (e.g., an optical density (OD) of 3 or higher). This increased film thickness hinders pattern formation via wet etching, and the effect of shortening the wet etching time is limited due to the increased film thickness. On the other hand, if the atomic ratio of the transition metal to silicon is set to the aforementioned ratio (transition metal: silicon = 1:3 or higher), there are advantages such as improved washability of the pattern-forming film. Therefore, deviating from this range of transition metal to silicon composition ratio is also undesirable.

Therefore, the inventors changed their approach and studied how adjusting the sputtering gas pressure within the film-forming chamber alters the film structure. When forming a pattern-forming thin film on a substrate, the sputtering gas pressure within the film-forming chamber is typically set to 0.1–0.5 Pa. However, the inventors intentionally set the sputtering gas pressure to be greater than 0.5 Pa to form the pattern-forming thin film. Furthermore, it was discovered that forming the pattern-forming thin film at a sputtering gas pressure between 0.8 Pa and 3.0 Pa provides suitable characteristics for a thin film, and when forming a transfer pattern on the pattern-forming thin film using wet etching, the etching time can be significantly shortened, resulting in a transfer pattern with a good cross-sectional shape. Moreover, the pattern-forming thin film formed in this manner exhibits a columnar structure not observed in conventional pattern-forming thin films. The inventors have conducted further focused research, attempting to make the pattern-forming film consist of multiple layers including an upper layer and a lower layer. While maintaining a sputtering gas pressure of 0.8 Pa to 3.0 Pa, the sputtering gas pressure during the formation of the upper layer is lower than that during the formation of the lower layer. Specifically, the inventors have attempted to achieve a higher vacuum level in the film-forming chamber during the formation of the upper layer compared to the vacuum level during the formation of the lower layer. It has been found that when a pattern-forming film including an upper and lower layer is formed in this manner, it possesses the aforementioned suitable characteristics for a film, and can form a transfer pattern that meets the requirements for washability and edge roughness in pattern-forming films or transfer patterns. Furthermore, the upper and lower layers of the pattern-forming film formed in this manner both possess the aforementioned columnar structure, with the size of the particles constituting the columnar structure in the upper layer being smaller than the size of the particles constituting the columnar structure in the lower layer. This invention was achieved through dedicated research as described above and has the following structure.

(Composition 1) A photomask substrate, characterized in that: it has a pattern forming film on a transparent substrate, and the photomask substrate is a master substrate for forming a photomask with a transfer pattern on the transparent substrate by wet etching of the pattern forming film, the pattern forming film containing a transition metal and silicon, the pattern forming film having a columnar structure, the pattern forming film comprising an upper layer and a lower layer, the average size of the particles constituting the columnar structure in the upper layer being smaller than the average size of the particles constituting the columnar structure in the lower layer.

(Formula 2) The photomask substrate as described in Formula 1 is characterized in that the atomic ratio of the transition metal to silicon contained in the thin film for forming the above pattern is transition metal: silicon = 1:3 or more and 1:15 or less.

(Formula 3) A photomask substrate as described in 1 or 2 is characterized in that the thin film for forming the above pattern contains at least nitrogen or oxygen. (Formula 4) A photomask substrate as described in any one of 1 to 3 is characterized in that the above transition metal is molybdenum.

(Form 5) The photomask substrate as described in any of 1 to 4 is characterized in that the thin film for forming the above pattern is a phase shift film having the following optical characteristics, namely, a transmittance of 1% to 80% for the representative wavelength of the exposed light and a phase difference of 160° to 200°.

(Construction 6) A photomask substrate as described in any of 1 to 5, characterized in that: an etching mask film with etching selectivity different from that of the pattern-forming film is provided on the pattern-forming film. (Construction 7) A photomask substrate as described in 6, characterized in that: the etching mask film comprises a material containing chromium and substantially free of silicon.

(Form 8) A method for manufacturing a photomask substrate, characterized in that: a pattern-forming thin film containing a transition metal and silicon is formed on a transparent substrate by sputtering, wherein a transition metal silicide target containing a transition metal and silicon is used in a film-forming chamber, and the sputtering gas pressure in the film-forming chamber supplied with sputtering gas is 0.8 Pa or more and 3.0 Pa or less, the pattern-forming thin film includes an upper layer and a lower layer, and the sputtering gas pressure in the film-forming chamber when forming the upper layer is lower than the sputtering gas pressure in the film-forming chamber when forming the lower layer.

(Construction 9) The method of manufacturing the photomask substrate as described in Construction 8 is characterized in that the atomic ratio of the transition metal to silicon in the transition metal silicate target is transition metal: silicon = 1:3 or more and 1:15 or less.

(Construction 10) The method for manufacturing a photomask substrate as described in Construction 8 or 9 is characterized in that: an etching mask film is formed on the aforementioned pattern-forming thin film using a sputtering target containing a material having etching selectivity different from that of the pattern-forming thin film. (Construction 11) The method for manufacturing a photomask substrate as described in Construction 10 is characterized in that: the aforementioned pattern-forming thin film and the aforementioned etching mask film are formed using an inline sputtering apparatus.

(Form 12) A method for manufacturing a photomask, characterized by comprising the following steps: preparing a photomask substrate as described in any one of Forms 1 to 5, or manufacturing a photomask substrate using a method for manufacturing a photomask substrate as described in Forms 8 or 9; forming an anti-corrosion film on the aforementioned pattern-forming thin film; using the anti-corrosion film pattern formed from the aforementioned anti-corrosion film as a mask to perform wet etching on the aforementioned pattern-forming thin film, thereby forming a transfer pattern on the aforementioned transparent substrate.

(Form 13) A method for manufacturing a photomask, characterized by comprising the following steps: preparing a photomask substrate as described in Form 6 or 7, or a photomask substrate manufactured using a method for manufacturing a photomask substrate as described in Form 10 or 11; forming an etching resist film on the etching mask film; performing wet etching on the etching mask film using the etching mask film pattern formed from the etching resist film as a mask, thereby forming an etching mask film pattern on the pattern forming film; performing wet etching on the pattern forming film using the etching mask film pattern as a mask, thereby forming a transfer pattern on the transparent substrate. (Construction 14) A method for manufacturing a display device, characterized in that it includes an exposure step in which a photomask obtained using the photomask manufacturing method as described in Construction 12 or 13 is placed on a photomask stage of an exposure apparatus, and the transfer pattern formed on the photomask is exposed and transferred to an anti-etching agent formed on a substrate of the display device. [Effects of the Invention]

According to the photomask substrate or the method for manufacturing the photomask substrate of the present invention, when a desired fine transfer pattern is formed by wet etching of a thin film for transferring the pattern, even if the thin film for pattern formation is a silicon-rich metal silicate compound from the viewpoint of washability, a photomask substrate can be obtained in which the transmittance of the transparent substrate does not decrease due to damage to the substrate by the wet etching solution, and a transfer pattern with good cross-sectional shape can be formed in a shorter etching time, which meets the washability required in the thin film for pattern formation or the transfer pattern, and meets the required line edge roughness.

Furthermore, according to the photomask manufacturing method of the present invention, the photomask is manufactured using the aforementioned photomask substrate. Therefore, even when the pattern-forming film is made of a silicon-rich metallic silicate compound from the viewpoint of washability, there is no decrease in the transmittance of the transparent substrate due to damage to the substrate by wet etching solution. This allows for the manufacture of a photomask with good transfer accuracy, meeting the washability requirements of the pattern-forming film or transfer pattern, and satisfying the required line edge roughness. This photomask can accommodate the miniaturization of line and gap patterns or contact holes.

Furthermore, according to the manufacturing method of the display device of the present invention, a display device is manufactured using a photomask manufactured using the above-mentioned photomask substrate or a photomask obtained by the above-mentioned photomask manufacturing method. Therefore, it is possible to manufacture a display device having fine lines and gap patterns or contact holes.

Embodiments 1 and 2 will be described below. The phase-shifting photomask substrate of Embodiment 1 is a mother plate, which is used to perform wet etching on the phase-shifting film by using an etching mask film pattern with a desired pattern formed on it as a mask, thereby forming a phase-shifting photomask with a phase-shifting film pattern on a transparent substrate. Furthermore, the phase-shifting photomask substrate of Embodiment 2 is a mother plate, which is used to perform wet etching on the phase-shifting film by using an anti-corrosion film pattern with a desired pattern formed on it as a mask, thereby forming a phase-shifting film with a phase-shifting film pattern on a transparent substrate.

Figure 1 is a schematic diagram showing the film structure of the phase-shifting photomask substrate 10 according to Embodiment 1. The phase-shifting photomask substrate 10 shown in Figure 1 includes a transparent substrate 20, a phase-shifting film 30 formed on the transparent substrate 20, and an etching mask film 40 formed on the phase-shifting film 30. Figure 2 is a schematic diagram showing the film structure of the phase-shifting photomask substrate 10 according to Embodiment 2. The phase-shifting photomask substrate 10 shown in Figure 2 includes a transparent substrate 20 and a phase-shifting film 30 formed on the transparent substrate 20. Moreover, as shown in Figures 1 and 2, the phase-shifting film 30 includes an upper layer 31 and a lower layer 32. Hereinafter, the transparent substrate 20, the phase-shifting film 30, and the etching mask film 40 constituting the phase-shifting photomask substrate 10 of Embodiments 1 and 2 will be described.

The transparent substrate 20 is transparent to the light being exposed. When the transparent substrate 20 is designed to have no surface reflection loss, it has a transmittance of 85% or more, preferably 90% or more, to the light being exposed. The transparent substrate 20 is made of a material containing silicon and oxygen, and can be made of glass materials such as synthetic quartz glass, quartz glass, aluminosilicate glass, sodium-calcium glass, or low-thermal-expansion glass ( _SiO2 - _TiO2 glass, etc.). When the transparent substrate 20 is made of low-thermal-expansion glass, it can suppress the positional change of the phase shift film pattern caused by thermal deformation of the transparent substrate 20. Furthermore, transparent substrates 20 used for display devices typically use a rectangular substrate with a short side length of 300 mm or more. The phase-shifting mask substrate of this invention can stably transfer a phase-shifting mask with a micro-phase-shifting film pattern, such as less than 2.0 μm, formed on a transparent substrate, even if the short side length of the transparent substrate is larger than 300 mm.

The phase shift film 30 comprises a transition metal silicide material containing a transition metal and silicon. Suitable transition metals include molybdenum (Mo), tantalum (Ta), tungsten (W), titanium (Ti), and zirconium (Zr), with molybdenum (Mo) being particularly preferred. Furthermore, the phase shift film 30 preferably contains at least nitrogen or oxygen. In the aforementioned transition metal silicide material, oxygen, as a light element component, has a lower extinction coefficient compared to nitrogen, which is also a light element component. Therefore, the content of other light element components (such as nitrogen) used to obtain the desired transmittance can be reduced, and the reflectivity of the front and back sides of the phase shift film 30 can also be effectively reduced. Furthermore, in the aforementioned transition metal silicate-based materials, nitrogen, as a light element component, has the effect of not reducing the refractive index compared to oxygen, which is also a light element component. Therefore, it can be used to achieve a thinner film with the desired phase difference. Moreover, the total content of light element components, including oxygen and nitrogen, 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 ideally, 50 atomic% or more and 65 atomic% or less. Furthermore, when oxygen is present in the phase shift film 30, in terms of defect quality and chemical resistance, the oxygen content is ideally greater than 0 atomic% and less than 25 atomic%. Furthermore, within the aforementioned range of total light element component content, it is preferable that the total content of light element components in the upper layer 31 of the phase shift film 30 is less than the total content of light element components in the lower layer 32. By setting the relationship between the total content of light element components in the upper layer 31 and the lower layer 32 as described above, the refractive index n2 and extinction coefficient k2 of the lower layer 32 at the representative wavelength of the exposed light can be made smaller than the refractive index n1 and extinction coefficient k1 of the upper layer 31. Therefore, the back reflectance at the representative wavelength of the exposed light can be reduced. Specifically, by appropriately adjusting the refractive index, extinction coefficient, and film thickness of the upper layer 31 and the lower layer 32, the back reflectance of the phase shift film 30 at the representative wavelength of the exposed light (e.g., h-line (wavelength 405 nm)) can be made less than 15%. By making the back reflectance of the phase shift film 30 less than 15%, the back reflectance when the phase shift photomask is placed on the exposure apparatus can be suppressed, thereby suppressing backlighting to the optical system of the exposure apparatus. Therefore, the pattern transfer characteristics of using a phase-shifted photomask are also advantageous, and thus superior. From the perspective of pattern transfer characteristics, the back reflectance of the phase-shifted film 30 at the representative wavelength of the exposed light is preferably below 10%, and more preferably below 5%. Examples of transition metal silicate materials include: nitrides of transition metal silicates, oxides of transition metal silicates, oxynitrides of transition metal silicates, and carbonitrides of transition metal silicates. Furthermore, to easily obtain excellent patterned cross-sectional shapes through wet etching, the transition metal silicate material is preferably a molybdenum silicate (MoSi), a zirconium silicate (ZrSi), or a molybdenum-zirconium silicate (MoZrSi), with molybdenum silicate (MoSi) being particularly preferred. In addition to oxygen and nitrogen, the phase shift film 30 may also contain other light elements such as carbon or helium to reduce film stress or control the wet etching rate. The phase shift film 30 has the function of adjusting the reflectivity (hereinafter sometimes referred to as back reflectivity) of light incident from the transparent substrate 20 side, and the function of adjusting the transmittance and phase difference of exposed light. The phase shift film 30 can be formed by sputtering.

The phase-shifting film 30 has a columnar structure. This columnar structure can be confirmed by cross-sectional SEM (scanning electron microscope) observation of the phase-shifting film 30. That is, the columnar structure in this invention refers to the state in which the particles of the transition metal silicide compound containing the transition metal and silicon constituting the phase-shifting film 30 have a columnar particle structure extending towards the film thickness direction of the phase-shifting film 30 (the particle stacking direction). Furthermore, in this case, particles with a length in the film thickness direction longer than their length in the perpendicular direction are considered columnar particles. That is, columnar particles extending towards the film thickness direction are formed throughout the surface of the transparent substrate 20 in the phase-shifting film 30. Furthermore, by adjusting the film formation conditions (sputtering pressure, etc.), the phase-shifting film 30 also forms sparse portions with a relatively lower density compared to columnar particles (hereinafter sometimes simply referred to as "sparse portions"). Moreover, in order to effectively suppress lateral erosion during wet etching, the cross-sectional shape of the pattern in the phase-shifting film 30 is further optimized. As a preferred form of the columnar structure of the phase-shifting film 30, it is preferable that the columnar particles extending along the film thickness direction are irregularly formed in the film thickness direction. It is even better that the columnar particles of the phase-shifting film 30 have inconsistent lengths along the film thickness direction. Furthermore, it is preferable that the sparse portions of the phase-shifting film 30 are continuously formed in the film thickness direction. Also, it is preferable that the sparse portions of the phase-shifting film 30 are intermittently formed in a direction perpendicular to the film thickness direction. By making the phase shift film 30 into the columnar structure described above, the wet etching solution can easily penetrate along the thickness direction of the phase shift film 30 during wet etching, thus accelerating the wet etching speed and significantly shortening the wet etching time. Therefore, even if the phase shift film 30 is a silicon-rich metal silicate compound, there is no decrease in the transmittance of the transparent substrate due to damage to the substrate by the wet etching solution. Furthermore, since the phase shift film 30 has a columnar structure extending along the thickness direction, lateral etching during wet etching is suppressed, resulting in a good pattern cross-sectional shape.

Furthermore, the average size of the columnar particles in the upper layer 31 of the phase-shifting film 30 is smaller than the average size of the columnar particles in the lower layer 32. The average size of the columnar particles mentioned here refers to the average size in the direction perpendicular to the thickness direction of the phase-shifting film 30 (in-plane direction). The average size of the columnar particles is determined by measuring the size of the columnar particles in the following region: a 300 nm in-plane region near the center of the thickness of the phase-shifting film 30 when observing a cross-sectional SEM image of the phase-shifting mask substrate 10 with the phase-shifting film 30 at 80,000x magnification. In other words, the frequency of occurrence of the sparse portion in the upper layer 31 of the phase-shifting film 30 is generally less than that of the sparse portion of the columnar structure in the lower layer 32. With this configuration of the phase shift film 30, the average size of the columnar particles in the upper layer 31 is smaller than that in the lower layer 32 (there are fewer sparse portions of the columnar structure). Therefore, the required washability of the phase shift film 30 can be met, and the edge roughness of the line when patterning the phase shift film 30 also meets the required characteristics. On the other hand, the average size of the columnar particles in the lower layer 32 is larger than that in the upper layer 31 (there are more sparse portions of the columnar structure). Therefore, lateral etching during wet etching can be effectively suppressed, thereby enabling the phase shift film pattern obtained by wet etching of the phase shift film 30 to have a good cross-sectional shape. That is, the phase shift film 30 with such an upper layer 31 and a lower layer 32 can form a phase shift film pattern that meets the required washability, the required line edge roughness, and the desired cross-sectional shape. Here, the average size of the main particles of the columnar structure in the upper layer 31 is preferably 5 to 30 nm, and the average size of the particles of the columnar structure in the lower layer 32 is preferably 10 to 40 nm.

The atomic ratio of the transition metal to silicon in the phase shift film 30 is preferably 1:3 to 1:15. Within this range, the effect of the columnar structure in suppressing the decrease in wet etching rate during pattern formation of the phase shift film 30 is enhanced. Furthermore, it improves the washability of the phase shift film 30 and also facilitates increased transmittance. To improve the washability of the phase shift film 30, the ideal atomic ratio of the transition metal to silicon is 1:4 to 1:15, and more ideally, 1:5 to 1:15.

The transmittance of the phase-shifting film 30 to the exposed light meets the value required for being a phase-shifting film 30. For light of a specific wavelength (hereinafter referred to as the representative wavelength) contained in the exposed light, the transmittance of the phase-shifting film 30 is preferably 1% to 80%, more preferably 15% to 65%, and even more preferably 20% to 60%. That is, when the exposed light is a composite light containing light in the wavelength range of 313 nm to 436 nm, the phase-shifting film 30 has the aforementioned transmittance to the representative wavelength contained in that wavelength range. For example, when the exposed light is a composite light containing the i-line, h-line, and g-line, the phase-shifting film 30 has the aforementioned transmittance to any one of the i-line, h-line, and g-line. The transmittance can be measured using a phase shift measurement device or the like.

The phase shift film 30 has a phase difference with respect to the exposed light that satisfies the value required for a phase shift film 30. For the representative wavelength light contained in the exposed light, the phase difference of the phase shift film 30 is preferably 160° to 200°, and more preferably 170° to 190°. This property allows the phase of the representative wavelength light contained in the exposed light to be changed to 160° to 200°. Therefore, a phase difference of 160° to 200° is generated between the representative wavelength light passing through the phase shift film 30 and the representative wavelength light passing only through the transparent substrate 20. That is, when the exposed light is a composite light containing light in the wavelength range of 313 nm to 436 nm, the phase shift film 30 has the aforementioned phase difference with respect to the representative wavelength light contained in that wavelength range. For example, when the exposed light system is a composite light containing i-line, h-line, and g-line, the phase shift film 30 has the aforementioned phase difference with respect to any one of the i-line, h-line, and g-line. The phase difference can be measured using a phase shift measurement device or the like.

Furthermore, the refractive index and extinction coefficient of the upper layer 31 of the phase-shifting film 30 are both greater than those of the lower layer 32. By appropriately setting the film thicknesses of the upper layer 31 and the lower layer 32, the back reflectivity of the phase-shifting film 30 can be reduced. The back reflectivity of the phase-shifting film 30 is 15% or less, preferably 10% or less, at the representative wavelength in the wavelength range of 365 nm to 436 nm. Also, when the exposed light contains j-lines, the back reflectivity of the phase-shifting film 30 is preferably 20% or less, more preferably 17% or less, and even more preferably 15% or less, at the representative wavelength in the wavelength range of 313 nm to 436 nm. Ideally, the back reflectance of the phase-shifting film 30 is 15% or less, and more preferably 10% or less, across the entire wavelength range of 365 nm to 436 nm. Furthermore, the back reflectance of the phase-shifting film 30 is preferably 0.2% or more at a representative wavelength in the 365 nm to 436 nm wavelength range, and preferably 0.2% or more at a representative wavelength in the 313 nm to 436 nm wavelength range. Ideally, the back reflectance of the phase-shifting film 30 is 0.2% or more across the entire wavelength range of 365 nm to 436 nm, or preferably 0.2% or more across the entire wavelength range of 313 nm to 436 nm. The back reflectance can be measured using a spectrophotometer or similar instrument.

Furthermore, in these embodiments, the phase shift film 30 is described as consisting of two layers, an upper layer 31 and a lower layer 32, but it is not limited to this configuration and may also consist of three or more layers. In this case, it is preferable that the size of the columnar particles in the upper layer is smaller than the average size of the columnar particles in the lower layer.

An etching mask film 40 is disposed above the phase shift film 30 and comprises a material that is etch-resistant to the etching solution used to etch the phase shift film 30 (but with different etching selectivity than the phase shift film 30). Furthermore, the etching mask film 40 may function to block the transmission of light during exposure, and may also function to reduce the surface reflectivity of the phase shift film 30 in such a way that the surface reflectivity of light incident from the phase shift film 30 side is less than 15% in the wavelength region of 350 nm to 436 nm. The etching mask film 40 comprises a chromium-based material containing chromium (Cr). More specifically, examples of chromium-based materials include those containing chromium (Cr) or those containing chromium (Cr) and at least one of oxygen (O), nitrogen (N), and carbon (C). Alternatively, materials containing chromium (Cr) and at least one of oxygen (O), nitrogen (N), and carbon (C), and further containing fluorine (F), may be cited. For example, materials constituting the etching mask film 40 may include: Cr, CrO, CrN, CrF, CrCO, CrCN, CrON, CrCON, and CrCONF. Furthermore, the etching mask film 40 preferably contains a material that is substantially free of silicon. Here, a material that is substantially free of silicon refers to a material in the etching mask film 40 containing silicon at a content of 2 atomic percent or less. Also, it is preferable that the silicon content in the etching mask film 40 is below the detection limit of the measuring device. The etching mask film 40 can be formed by sputtering.

When the etching mask film 40 functions to block the transmission of light during exposure, the optical density of the exposed light in the area where the phase shift film 30 and the etching mask film 40 are stacked is preferably 3 or higher, more preferably 3.5 or higher, and even more preferably 4 or higher. The optical density can be measured using a spectrophotometer or an OD (optical density) meter.

Depending on its function, the etching mask film 40 may consist of a single film with uniform composition, a plurality of films with different compositions, or a single film with continuously varying thickness in the thickness direction.

Furthermore, the phase shift mask substrate 10 shown in Figure 1 has an etching mask 40 on the phase shift film 30, but the present invention can also be applied to a phase shift mask substrate with an etching mask 40 on the phase shift film 30 and an anti-corrosion film on the etching mask 40.

Next, the manufacturing methods of the phase-shifting mask substrate 10 in embodiments 1 and 2 will be described. The phase-shifting mask substrate 10 shown in FIG1 is manufactured by performing the following phase-shifting film formation step and etching mask film formation step. The phase-shifting mask substrate 10 shown in FIG2 is manufactured by performing the phase-shifting film formation step. The steps are described in detail below.

1. Phase shift film formation step First, prepare a transparent substrate 20. The transparent substrate 20 can be made of any glass material such as synthetic quartz glass, quartz glass, aluminosilicate glass, sodium calcium glass, low thermal expansion glass ( _SiO2 - _TiO2 glass, etc.), as long as it is transparent to the exposed light.

Next, a phase shift film 30 is formed on the transparent substrate 20 by sputtering. In the formation of the phase shift film 30, a transition metal silicate containing a transition metal and silicon, which will become the main component of the material constituting the phase shift film 30, or a transition metal silicate target containing a transition metal, silicon, and oxygen and/or nitrogen is used as a sputtering target, for example, in a sputtering atmosphere containing an inert gas or a sputtering atmosphere containing a mixture of the aforementioned inert gas and an active gas. The inert gas includes at least one gas selected from the group consisting of helium, neon, argon, krypton, and xenon. The active gas is selected from the group consisting of oxygen, nitrogen, carbon dioxide, nitric oxide, and nitrogen dioxide and includes at least oxygen and nitrogen. Furthermore, the phase-shifting film 30 is formed in a gas atmosphere where the gas pressure in the film-forming chamber supplied with sputtering gas is between 0.8 Pa and 3.0 Pa. By setting the gas pressure range in this way, a columnar structure can be formed in the phase-shifting film 30. This columnar structure can suppress lateral erosion during the formation of the pattern and achieve a high etching rate. Here, when the atomic ratio of the transition metal to silicon in the transition metal silicate target is between 1:3 and 1:15, the effect of the columnar structure in suppressing the decrease in wet etching rate is enhanced, which can improve the washability of the phase-shifting film 30 and easily improve the transmittance, which is better in all these aspects. When forming the phase shift film 30, based on satisfying the sputtering gas pressure of 0.8 Pa to 3.0 Pa, the sputtering gas pressure when forming the upper layer 31 of the phase shift film 30 is lower than the sputtering gas pressure when forming the lower layer 32 of the phase shift film 30 (that is, the vacuum degree in the film-forming chamber when forming the upper layer 31 is better than the vacuum degree in the film-forming chamber when forming the lower layer 32), thus forming a phase shift film 30 including the upper layer 31 and the lower layer 32. Here, the sputtering gas pressure when forming the upper layer 31 is preferably 0.8 Pa to 1.5 Pa, and the sputtering gas pressure when forming the lower layer 32 is preferably 1.2 Pa to 3.0 Pa. The sputtering gas pressure can be adjusted by controlling the opening of the main valve of the vacuum pump connected to the film-forming chamber. By adjusting the vacuum levels during the formation of the upper layer 31 and the lower layer 32 in this manner, the size of the particles forming the columnar structure in the upper layer 31 can be made smaller than the size of the particles forming the columnar structure in the lower layer 32. In this way, a phase-shifting photomask substrate 10 can be obtained, namely, a phase-shifting photomask substrate 10 that can form a phase-shifting film pattern 30a with a good cross-sectional shape and meeting the required washability and the required line edge roughness of the phase-shifting film 30 or phase-shifting film pattern 30a. The difference between the sputtering gas pressure when forming the upper layer 31 and the sputtering gas pressure when forming the lower layer 32 is preferably 0.3 Pa to 1.2 Pa. More preferably 0.4 Pa to 1.0 Pa. When the difference between the sputtering gas pressure when forming the upper layer 31 and the sputtering gas pressure when forming the lower layer 32 is less than 0.3 Pa, the difference in performance (good cross-sectional shape, required washability, or edge roughness) between the single-layer phase shift film 30 or the phase shift film 30 formed under the same film formation conditions and the phase shift film 30 of the present invention becomes smaller. Furthermore, when the difference between the sputtering gas pressure during the formation of the upper layer 31 and the sputtering gas pressure during the formation of the lower layer 32 exceeds 1.2 Pa, the lateral etching amount of the upper layer 31 and the lower layer 32 will differ when the phase shift film 30 is patterned by wet etching. Therefore, it is easy to produce a step difference in the cross-sectional shape of the phase shift film pattern, which is undesirable.

The composition and thickness of the phase shift film 30 are adjusted to achieve the aforementioned phase difference and transmittance. The composition of the phase shift film 30 can be controlled by the content ratio of elements constituting the sputtering target (e.g., the ratio of the content of transition metal to the content of silicon), the composition and flow rate of the sputtering gas, etc. The thickness of the phase shift film 30 can be controlled by sputtering power, sputtering time, etc. Furthermore, it is preferable to use an inline sputtering apparatus to form the phase shift film 30. When the sputtering apparatus is an inline sputtering apparatus, the thickness of the phase shift film 30 can also be controlled by the substrate transport speed. In this way, the content of light element components, including oxygen and nitrogen, in the phase shift film 30 is controlled to be 40 atomic% to 70 atomic% or more. Furthermore, it is preferable that the upper layer 31 of the phase shift film 30 is thinner than the lower layer 32. This is because the upper layer 31 primarily functions to improve the washability of the phase shift film 30 or reduce the roughness of the line edges, while the lower layer 32 primarily functions to shorten the wet etching time or improve the cross-sectional shape. More specifically, the overall thickness of the phase shift film 30 is preferably 120 nm to 250 nm, and the thickness of the upper layer 31 is preferably 10 nm to 50 nm, while the thickness of the lower layer 32 is preferably 70 nm to 240 nm.

When the phase shift film 30 is composed of multiple films with different compositions, the composition and flow rate of the sputtering gas are appropriately adjusted to perform the above-described film formation process multiple times. Alternatively, targets with different ratios of elements constituting the sputtering target can be used to form the phase shift film 30. When performing multiple film formation processes, the sputtering power applied to the sputtering target can also be varied in each film formation process.

2. Surface Treatment Step: When the phase shift film 30 contains transition metal silicate oxides containing transition metals, silicon, and oxygen, or oxygen-containing transition metal silicate nitrides containing transition metals, silicon, oxygen, and nitrogen, a surface treatment step to adjust the surface oxidation state of the phase shift film 30 can be performed to suppress the etchant penetration caused by the presence of transition metal oxides. Furthermore, when the phase shift film 30 contains transition metal silicate nitrides containing transition metals, silicon, and nitrogen, the content of transition metal oxides is lower compared to the aforementioned oxygen-containing transition metal silicate materials. Therefore, when the material of the phase shift film 30 is a transition metal silicate nitride, the above-mentioned surface treatment step can be performed, or it can be omitted. Examples of surface treatment steps for adjusting the surface oxidation state of the phase shift film 30 include: surface treatment using an acidic aqueous solution, surface treatment using an alkaline aqueous solution, and surface treatment using a drying process such as ashing. The phase shift mask substrate 10 of Embodiment 2 is obtained in this manner. In the fabrication of the phase shift mask substrate 10 of Embodiment 1, the following etching mask film formation step is further performed.

3. Etching Mask Film Formation Step: After the phase shift film formation step, surface treatment is performed to adjust the surface oxidation state of the phase shift film 30 as needed. Then, an etching mask film 40 is formed on the phase shift film 30 using sputtering. It is preferable to use an inline sputtering apparatus to form the etching mask film 40. When the sputtering apparatus is an inline sputtering apparatus, the thickness of the etching mask film 40 can also be controlled by the transport speed of the transparent substrate 20. In the formation of the etching mask film 40, a sputtering target containing chromium or chromium compounds (chromium oxide, chromium nitride, chromium carbide, chromium oxynitride, chromium carbonitride, etc.) is used, for example, in a sputtering atmosphere containing an inert gas or a sputtering atmosphere containing a mixture of the aforementioned inert gas and an active gas. The inert gas is a gas selected from the group consisting of helium, neon, argon, krypton and xenon. The active gas is a gas selected from the group consisting of oxygen, nitrogen, nitric oxide, nitrogen dioxide, carbon dioxide, hydrogen carbide gases and fluorine gases. Examples of hydrogen carbide-based gases include methane, butane, propane, and styrene. Furthermore, by adjusting the gas pressure within the film-forming chamber during sputtering, the etching mask film 40 can be made into a columnar structure, similar to the phase-shifting film 30. This suppresses lateral etching during pattern formation and enables a high etching rate.

When the etching mask film 40 is composed of a single, uniformly formed film, the above-described film deposition 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 multiple films with different compositions, the composition and flow rate of the sputtering gas are changed in each film deposition process, and the above-described film deposition process is performed multiple times. When the etching mask film 40 is composed of a single film with continuously varying thickness in the thickness direction, the composition and flow rate of the sputtering gas are changed as the film deposition process proceeds, and the above-described film deposition process is performed only once. The phase-shifting photomask substrate 10 of Embodiment 1 is obtained in this manner.

Furthermore, in the phase-shifting mask substrate 10 shown in FIG. 1, an etching mask film 40 is provided on the phase-shifting film 30. Therefore, an etching mask film formation step is performed when manufacturing the phase-shifting mask substrate 10. Also, when manufacturing a phase-shifting mask substrate with an etching mask film 40 provided on the phase-shifting film 30 and an anti-etching film provided on the etching mask film 40, an anti-etching film is formed on the etching mask film 40 after the etching mask film formation step. Furthermore, in the phase-shifting mask substrate 10 shown in FIG. 2, when manufacturing a phase-shifting mask substrate with an anti-etching film provided on the phase-shifting film 30, an anti-etching film is formed after the phase-shifting film formation step.

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

In the phase-shifting mask substrate 10 of embodiments 1 and 2, when the phase-shifting film 30 is patterned by wet etching, etching in the thickness direction is promoted while lateral etching is suppressed. Therefore, the phase-shifting film pattern can be formed in a shorter etching time. That is, the phase-shifting film pattern has a good cross-sectional shape, has the desired transmittance (e.g., high transmittance), and meets the required washability and line edge roughness of the phase-shifting film or phase-shifting film pattern. Therefore, a phase-shifting mask substrate is obtained in which the transmittance of the transparent substrate is not reduced due to damage to the substrate by the wet etching solution, and a phase-shifting mask that can transfer high-precision phase-shifting film patterns with good accuracy can be manufactured.

Embodiments 3 and 4. The manufacturing method of the phase-shifting mask is explained in Embodiments 3 and 4.

Figure 3 is a schematic diagram illustrating the manufacturing method of the phase-shifting mask according to Embodiment 3. Figure 4 is a schematic diagram illustrating the manufacturing method of the phase-shifting mask according to Embodiment 4. The manufacturing method of the phase-shifting mask shown in Figure 3 is a method for manufacturing the phase-shifting mask using the phase-shifting mask substrate 10 shown in Figure 1, including the following steps: forming an etching resist film on the etching mask 40 of the phase-shifting mask substrate 10; forming an etching resist pattern 50 by drawing and developing a desired pattern on the etching resist film (first etching resist pattern formation step); and applying the etching resist film... Pattern 50 is used as a mask to wet-etch the etching mask film 40, thereby forming an etching mask film pattern 40a on the phase shift film 30 (first etching mask film pattern formation step); and the etching mask film pattern 40a is used as a mask to wet-etch the phase shift film 30, thereby forming a phase shift film pattern 30a on the transparent substrate 20 (phase shift film pattern formation step). Furthermore, it further includes a second anti-corrosion film pattern formation step and a second etching mask film pattern formation step.

The method for manufacturing the phase-shifting mask shown in Figure 4 is a method for manufacturing the phase-shifting mask using the phase-shifting mask substrate 10 shown in Figure 2, including the following steps: forming an anti-corrosion film on the phase-shifting mask substrate 10; and forming an anti-corrosion film pattern 50 by drawing and developing a desired pattern on the anti-corrosion film (first anti-corrosion film pattern forming step); using the anti-corrosion film pattern 50 as a mask to perform wet etching on the phase-shifting film 30, thereby forming a phase-shifting film pattern 30a on the transparent substrate 20 (phase-shifting film pattern forming step). The following describes in detail each step of the manufacturing process of the phase-shifting mask in embodiments 3 and 4.

Manufacturing Steps of Phase-Shifted Mask in Embodiment 3: 1. First Anti-etching Film Pattern Formation Step: In the first anti-etching film pattern formation step, an anti-etching film is first formed on the etching mask film 40 of the phase-shifted mask substrate 10 of Embodiment 1. There are no particular limitations on the anti-etching film material used. For example, any material sensitive to laser light with a wavelength selected from the 350 nm to 436 nm wavelength range is acceptable. Furthermore, the anti-etching film can be either positive or negative. Subsequently, a desired pattern is drawn on the anti-etching film using laser light with a wavelength selected from the 350 nm to 436 nm wavelength range. The pattern drawn on the anti-etching film is to be formed on the phase-shifted film 30. Examples of patterns for depicting the anti-corrosion film include lines and gaps or holes. Subsequently, the anti-corrosion film is developed using a specific developing solution, as shown in Figure 3(a), forming the first anti-corrosion film pattern 50 on the etching mask film 40.

2. First Etching Mask Film Pattern Formation Step: In the first etching mask film pattern formation step, the first anti-corrosion film pattern 50 is first used as a mask to etch the etching mask film 40, thereby forming the first etching mask film pattern 40a. The etching mask film 40 is formed from a chromium-based material containing chromium (Cr). When the etching mask film 40 has a columnar structure, the etching speed is accelerated, and lateral etching can be suppressed, which is better in this respect. There are no particular restrictions on the etching solution used to etch the etching mask film 40, as long as it can selectively etch the etching mask film 40. For example, an etching solution containing ammonium cerium nitrate and perchloric acid can be used. Subsequently, the first anti-corrosion film pattern 50 is peeled off using an anti-corrosion stripping solution or by ashing, as shown in Figure 3(b). Depending on the situation, the subsequent phase shift film pattern formation step may be performed without peeling off the first anti-corrosion film pattern 50.

3. Phase Shift Film Pattern Formation Step: In the first phase shift film pattern formation step, the first etching mask film pattern 40a is used as a mask to wet-etch the phase shift film 30 containing the upper layer 31 and the lower layer 32, as shown in Figure 3(c), forming a phase shift film pattern 30a containing the upper layer pattern 31a and the lower layer pattern 32a. Examples of the phase shift film pattern 30a include line and gap patterns or hole patterns. There are no particular limitations on the etching solution used to etch the phase shift film 30, as long as it can selectively etch the phase shift film 30. Examples include etching solutions containing ammonium fluoride, phosphoric acid, and hydrogen peroxide; and etching solutions containing ammonium hydrogen fluoride and hydrogen peroxide. To ensure a good cross-sectional shape for the phase shift film pattern 30a, wet etching is preferably performed for a period longer than the time until the transparent substrate 20 is exposed in the phase shift film pattern 30a (the over-etching time). Considering the impact on the transparent substrate 20, the over-etching time is preferably set to a period of 20% of the appropriate etching time plus the appropriate etching time, and even better, it is set to a period of 10% of the appropriate etching time plus the appropriate etching time.

4. Second Anti-corrosion Film Pattern Forming Step: In the second anti-corrosion film pattern forming step, an anti-corrosion film covering the first etching mask film pattern 40a is first formed. There are no particular limitations on the anti-corrosion film material used. For example, any material sensitive to laser light with a wavelength selected from the 350 nm to 436 nm wavelength range can be used. Furthermore, the anti-corrosion film can be either positive or negative. Subsequently, a desired pattern is drawn on the anti-corrosion film using laser light with a wavelength selected from the 350 nm to 436 nm wavelength range. The pattern drawn on the anti-corrosion film can be a light-shielding band pattern that blocks light from the outer periphery of the area where the pattern is formed on the phase shift film 30, or a light-shielding band pattern that blocks light from the central portion of the phase shift film pattern, etc. Furthermore, based on the transmittance of the phase shift film 30 to the exposed light, the pattern drawn on the resist film may also be a pattern without a light-shielding band pattern that blocks light from the center of the phase shift film pattern 30a. Subsequently, the resist film is developed using a specific developing solution, as shown in FIG3(d), to form a second resist film pattern 60 on the first etch mask film pattern 40a.

5. Second Etching Mask Film Pattern Formation Step: In the second etching mask film pattern formation step, the second anti-corrosion film pattern 60 is used as a mask to etch the first etching mask film pattern 40a, as shown in Figure 3(e), to form the second etching mask film pattern 40b. The first etching mask film pattern 40a is formed from a chromium-based material containing chromium (Cr). There are no particular limitations on the etching solution used to etch the first etching mask film pattern 40a, as long as it can selectively etch the first etching mask film pattern 40a. For example, an etching solution containing ammonium cerium nitrate and perchloric acid can be used. Subsequently, the second resist pattern 60 is peeled off using an anti-corrosion stripping solution or by ashing. The phase-shifting photomask 100 is thus obtained. Furthermore, in the above description, the etching mask 40 was explained as having the function of blocking the transmission of light during exposure. However, when the etching mask 40 only functions as a hard mask during the etching of the phase-shifting film 30, the second resist pattern formation step and the second etching mask pattern formation step are not performed in the above description. After the phase-shifting film pattern formation step, the first etching mask pattern is peeled off to fabricate the phase-shifting photomask 100.

According to the manufacturing method of the phase-shifting mask in Embodiment 3, since the phase-shifting mask substrate of Embodiment 1 is used, the etching time can be shortened, and a phase-shifting film pattern with a good cross-sectional shape can be formed. Therefore, a phase-shifting mask that can transfer high-precision phase-shifting film patterns with good accuracy can be manufactured. The phase-shifting mask manufactured in this way can accommodate the miniaturization of line and gap patterns or contact holes.

Manufacturing Steps of Phase-Shifted Mask in Embodiment 4: 1. Anti-corrosion Film Pattern Formation Step: In the anti-corrosion film pattern formation step, an anti-corrosion film is first formed on the phase-shifting film 30 of the phase-shifted mask substrate 10 in Embodiment 2. The anti-corrosion film material used is the same as that described in Embodiment 3. Furthermore, if necessary, the phase-shifting film 30 may be surface-modified before forming the anti-corrosion film to ensure good adhesion between the anti-corrosion film and the phase-shifting film 30. Similarly, after forming the anti-corrosion film, a laser light with any wavelength selected from the wavelength region of 350 nm to 436 nm is used to draw the desired pattern on the anti-corrosion film. Subsequently, the resist film is developed using a specific developing solution, as shown in FIG. 4(a), forming a resist film pattern 50 on the phase shift film 30. 2. Phase Shift Film Pattern Formation Step In the phase shift film pattern formation step, the resist film pattern is used as a mask to etch the phase shift film 30, which includes the upper layer 31 and the lower layer 32, as shown in FIG. 4(b), forming a phase shift film pattern 30a including the upper pattern 31a and the lower pattern 32a. The etching solution or etching time for etching the phase shift film pattern 30a or the phase shift film 30 is the same as that described in Embodiment 3. Subsequently, the resist film pattern 50 is peeled off using an resist stripping solution or by ashing (FIG. 4(c)). A phase-shifting mask 100 is obtained in this manner. According to the manufacturing method of the phase-shifting mask in Embodiment 4, since the phase-shifting mask substrate of Embodiment 2 is used, there is no decrease in the transmittance of the transparent substrate caused by damage to the substrate from the wet etching solution. This shortens the etching time and allows for the formation of a phase-shifting film pattern with a good cross-sectional shape. Therefore, a phase-shifting mask capable of accurately transferring high-precision phase-shifting film patterns can be manufactured. The phase-shifting mask manufactured in this manner can accommodate miniaturization of line and gap patterns or contact holes.

Embodiment 5. In Embodiment 5, a method for manufacturing a display device will be described. The display device is manufactured by performing the following steps: using a phase shift mask 100 manufactured using the phase shift mask substrate 10 described above, or using a phase shift mask 100 manufactured by the method described above for manufacturing a phase shift mask 100 (mask placement step); and exposing and transferring a transfer pattern onto an anti-corrosion film on the display device (exposure step). Each step will be described in detail below.

1. Placement Step: In the placement step, the phase-shifted photomask manufactured in Embodiment 3 is placed on the photomask stage of the exposure apparatus. Here, the phase-shifted photomask is disposed opposite to the projection optical system of the exposure apparatus and the anti-corrosion film formed on the substrate of the display device.

2. Pattern Transfer Step: In the pattern transfer step, the phase-shifting photomask 100 is irradiated with exposure light to transfer the phase-shifting film pattern onto the anti-corrosion film formed on the display device substrate. The exposure light is a composite light containing multiple wavelengths selected from the wavelength region of 365 nm to 436 nm, or a monochromatic light selected by using a filter or the like from a wavelength region of 365 nm to 436 nm. For example, the exposure light is a composite light containing i-lines, h-lines, and g-lines, or a monochromatic light containing i-lines. Using composite light as the exposure light can increase the intensity of the exposure light and improve production capacity, thereby reducing the manufacturing cost of the display device.

According to the manufacturing method of the display device in Embodiment 3, a high-precision display device with high resolution and fine line and gap patterns or contact holes can be manufactured. Furthermore, in the above embodiments, the use of a phase-shifting photomask substrate with a phase-shifting film or a phase-shifting photomask with a phase-shifting film pattern as a photomask substrate with a pattern forming film or a photomask with a transfer pattern has been described, but it is not limited to these cases. For example, the present invention can also be applied to a binary photomask substrate with a light-shielding film as a pattern forming film or a binary photomask with a light-shielding film pattern. [Example]

Example 1.A. Phase-shifting photomask substrate and its manufacturing method In order to manufacture the phase-shifting photomask substrate of Example 1, a 1214-sized (1220 mm × 1400 mm) synthetic quartz glass substrate is first prepared as a transparent substrate 20.

Subsequently, the main surface of the synthetic quartz glass substrate is placed on a tray (not shown) with its main surface facing downwards, and then moved into the chamber of the inline sputtering apparatus. In order to form the lower layer 32 of the phase shift film 30 on the main surface of the transparent substrate 20, firstly, an inert gas containing argon (Ar) and nitrogen ( _N2 ) (Ar: 18 sccm, _N2 : 13 sccm) is introduced while the sputtering gas pressure in the first chamber is 1.6 Pa. Then, a sputtering power of 7.6 kW is applied to a first sputtering target containing molybdenum and silicon (molybdenum:silicon = 11:89) to deposit a molybdenum silicate nitride containing molybdenum, silicon, and nitrogen onto the main surface of the transparent substrate 20 via reactive sputtering, thereby forming a lower layer 32 with a thickness of 115 nm. Next, the opening of the main valve of the vacuum pump connected to the first chamber is adjusted to make the sputtering gas pressure in the first chamber 1.2 Pa. Under the same conditions as the lower layer 32, an upper layer 31 with a thickness of 30 nm is formed on top of the lower layer 32 via reactive sputtering. In this manner, a phase shift film 30 with a thickness of 145 nm is formed.

Next, the transparent substrate 20 with the phase shift film 30 is moved into the second chamber, and a mixture of argon (Ar) and nitrogen ( _N2 ) gas (Ar: 65 sccm, _N2 : 15 sccm) is introduced into the second chamber. Then, a sputtering power of 1.5 kW is applied to the second sputtering target containing chromium, and a chromium nitride (CrN) containing chromium and nitrogen (film thickness 15 nm) is formed on the phase shift film 30 by reactive sputtering. Next, a mixture of argon (Ar) and methane ( _CH4 :4.9%) gas (30 sccm) was introduced into the third chamber to achieve a specific vacuum level. A sputtering power of 8.5 kW was applied to the third sputtering target containing chromium, and a chromium carbide (CrC) containing chromium and carbon (film thickness 60 nm) was formed on CrN by reactive sputtering. Finally, under conditions that create a specific vacuum in the fourth chamber, a mixture of argon (Ar) and methane ( _CH4 : 5.5%) and a mixture of nitrogen ( _N2 ) and oxygen ( _O2 ) (Ar + _CH4 : 30 sccm, _N2 : 8 sccm, _O2 : 3 sccm) are introduced. A sputtering power of 2.0 kW is applied to the fourth sputtering target containing chromium, and chromium carbonitride (CrCON) (film thickness 30 nm) is formed on CrC by reactive sputtering. An etching mask film 40 with a stacked structure of CrN layer, CrC layer and CrCON layer is formed on the phase shift film 30 in the above manner. In this way, a phase-shifting photomask substrate 10 with a phase-shifting film 30 and an etching mask film 40 formed on a transparent substrate 20 is obtained.

The transmittance and phase difference of the phase-shifting film 30 on the obtained phase-shifting photomask substrate 10 were measured using an MPM-100 manufactured by Lasertec. In measuring the transmittance and phase difference of the phase-shifting film 30, a substrate with the phase-shifting film 30 formed on the main surface of a synthetic quartz glass substrate (a dummy substrate) was used, placed on the same tray. Before forming the etching mask film 40, the substrate with the phase-shifting film (dummy substrate) was removed from the chamber, and the transmittance and phase difference of the phase-shifting film 30 were measured. The results showed a transmittance of 25.1% (wavelength: 405 nm), a phase difference of 176° (wavelength: 405 nm), and a back reflectance of 9.4% (wavelength: 405 nm). Furthermore, a spectroscopic elliptic transilluminator (manufactured by J.A. Woollam) was used. The optical properties of the upper layer 31 and the lower layer 32 in the phase shift film 30 were measured using an M-2000D. The refractive index of the upper layer 31 is 2.49 and the extinction coefficient is 0.32. The refractive index of the lower layer 32 is 2.37 and the extinction coefficient is 0.24. Furthermore, regarding the upper layer 31, the optical properties were measured for a case where only the upper layer 31 is formed on another transparent substrate (the same method was used in Embodiment 2).

Furthermore, X-ray photoelectron spectroscopy (XPS) was used to perform depth-direction composition analysis on the obtained phase-shifting mask substrate 10. In the XPS depth-direction composition analysis results for the phase-shifting mask substrate 10, in the phase-shifting film 30, except for the gradient composition regions at the interface between the transparent substrate 20 and the phase-shifting film 30, and the gradient composition regions at the interface between the phase-shifting film 30 and the etching mask film 40, the atomic ratio of molybdenum to silicon is approximately fixed in the depth direction, at 1:5.6, falling within the range of 1:3 to 1:15. Furthermore, the content of each constituent element is as follows: in the upper layer 31, Mo is 7 atomic%, Si is 39 atomic%, N is 51 atomic%, and O is 3 atomic%; in the lower layer 32, Mo is 7 atomic%, Si is 39 atomic%, N is 46 atomic%, and O is 8 atomic%. Furthermore, the combined content of oxygen and nitrogen, which are light elements, is 54 atomic% in the upper layer 31 and 54 atomic% in the lower layer 32, both falling within the range of 50 atomic% to 65 atomic%. Moreover, the presence of oxygen in the phase-shifted film 30 is believed to be due to the presence of trace amounts of oxygen in the chamber during film formation caused by the high pressure of the sputtered gas (up to 0.8 Pa).

Next, cross-sectional SEM (scanning electron microscopy) observation was performed at 80,000x magnification at the center of the transferred pattern formation area on the obtained phase-shifting photomask substrate 10. The results confirmed that the phase-shifting film 30 has a columnar structure. That is, it was confirmed that the molybdenum silicate compound particles constituting the phase-shifting film 30 have columnar particle structures extending towards the thickness direction of the phase-shifting film 30. Moreover, it was confirmed that the columnar particle structure of the phase-shifting film 30 is irregularly formed in the thickness direction, and the length of the columnar particles in the thickness direction is also inconsistent. Furthermore, it was also confirmed that the sparse portion of the phase-shifting film 30 is continuously formed in the thickness direction. Furthermore, it was also confirmed that the average size of the columnar particles in the upper layer 31 of the phase-shifting film 30 is smaller than the average size of the columnar particles in the lower layer 32. The average size of the columnar particles in the upper layer 31 is 14 nm, and the average size of the columnar particles in the lower layer 32 is 22 nm.

B. Phase-Shifting Mask and its Manufacturing Method To manufacture a phase-shifting mask 100 using the phase-shifting mask substrate 10 manufactured as described above, a photoresist film is first coated onto the etching mask film 40 of the phase-shifting mask substrate 10 using an anti-corrosion coating apparatus. Subsequently, a photoresist film with a thickness of 520 nm is formed through heating and cooling steps. Then, a pattern is drawn on the photoresist film using a laser patterning apparatus, and after developing and rinsing steps, an anti-corrosion film pattern with a hole pattern of 1.5 μm aperture is formed on the etching mask film.

Subsequently, the anti-corrosion film pattern is used as a mask, and the etching mask film is wet-etched using a chromium etching solution containing ammonium nitrate and perchloric acid to form the first etching mask film pattern 40a.

Subsequently, using the first etching mask pattern 40a as a mask, the phase shift film 30 is wet-etched using a molybdenum silicate etching solution diluted with a mixture of ammonium hydrogen fluoride and hydrogen peroxide in pure water, thereby forming the phase shift film pattern 30a. To ensure the cross-sectional shape is vertical and to form the desired fine pattern, the wet etching is performed with an over-etching time of 110%. The appropriate etching time in Example 1 is 0.15 times that in the comparative example below, which significantly shortens the etching time. The resist pattern is then peeled off.

Subsequently, a photoresist film is coated using an anti-corrosion coating apparatus to cover the first etch mask film pattern 40a. Then, a photoresist film with a thickness of 520 nm is formed through heating and cooling steps. Next, the photoresist film is drawn using a laser patterning apparatus, and after developing and washing steps, a second anti-corrosion film pattern 60 is formed on the first etch mask film pattern 40a. This second anti-corrosion film pattern 60 is used to form a light-shielding band.

Subsequently, using the second resist film pattern 60 as a mask, wet etching is performed on the first etching mask film pattern 40a formed in the transfer pattern formation area using a chromium etching solution containing ammonium cerium nitrate and perchloric acid. Then, the second resist film pattern 60 is peeled off.

In this manner, a phase shift mask 100 is obtained on a transparent substrate 20, wherein a phase shift film pattern 30a with an aperture of 1.5 μm is formed in the transfer pattern forming area, and a light-shielding strip is formed by the stacking structure of the phase shift film pattern 30a and the etching mask film pattern 40b.

The cross-section of the obtained phase-shifting mask was observed using a scanning electron microscope. The cross-section of the phase-shifting film pattern is composed of the upper surface, lower surface, and side surface of the phase-shifting film pattern. The angle of the cross-section of the phase-shifting film pattern refers to the angle formed by the portion where the upper surface and side surface of the phase-shifting film pattern meet (upper side) and the portion where the side surface and lower surface meet (lower side). The angle of the cross-section of the obtained phase-shifting film pattern 30a of the phase-shifting mask is 75° or more, and it has a good cross-sectional shape. The phase-shifting film pattern 30a formed on the phase-shifting mask of Embodiment 1 has a cross-sectional shape that can fully exert the phase-shifting effect. It is believed that the mechanism by which the phase-shifting film 30 becomes a columnar structure, thereby achieving a good cross-sectional shape of the phase-shifting film pattern 30a, is as follows. The phase shift film 30 has columnar particle structures (columnar structures) in both the upper layer 31 and the lower layer 32, and the columnar particles extending along the film thickness direction are formed irregularly. Furthermore, the phase shift film 30 is formed in both the upper layer 31 and the lower layer 32 by a columnar particle portion with a relatively high density and a sparse portion with a relatively low density. Based on these facts, it is believed that when the phase shift film 30 is patterned by wet etching, the etching solution penetrates into the sparse portions of the phase shift film 30, thereby facilitating etching along the film thickness direction. On the other hand, columnar particles are irregularly formed in a direction perpendicular to the film thickness direction (the direction within the substrate plane), and the sparse portions in that direction are formed intermittently. Therefore, etching is less likely to proceed in that direction, and lateral etching is suppressed. As a result, a good cross-sectional shape that is close to vertical is obtained in the phase shift film pattern 30a. Furthermore, no penetration was observed at the interface with the etching mask film pattern and at the interface with the substrate in the phase shift film pattern. Therefore, a phase-shifting mask with excellent phase-shifting effect is obtained under exposure light containing light in the wavelength range of 300 nm to 500 nm, and more specifically, under exposure light containing composite light including i-line, h-line, and g-line. Furthermore, the edge roughness of the phase-shifting film pattern in the phase-shifting mask obtained in Example 1 was measured, and the result was below 30 nm, meeting the required level. Additionally, a cleaning test was conducted on the phase-shifting mask substrate and the phase-shifting mask obtained in Example 1, and the result met the required cleaning resistance. Therefore, it can be said that when the phase-shifting mask of Example 1 is placed on the mask stage of an exposure apparatus to perform exposure transfer on an anti-corrosion film on a display device, fine patterns less than 2.0 μm can be transferred with high precision.

Furthermore, in the phase shift film pattern 30a, the columnar structure of the phase shift film 30 is maintained. Also, the surface of the transparent substrate 20 exposed after removing the phase shift film 30 is relatively smooth, and the decrease in transmittance caused by the roughness of the transparent substrate 20 is negligible.

Example 2.A. Phase-Shifting Mask Substrate and Manufacturing Method Thereof To manufacture the phase-shifting mask substrate of Example 2, a 1214-sized (1220 mm × 1400 mm) synthetic quartz glass substrate is prepared as a transparent substrate, similar to Example 1. The synthetic quartz glass substrate is placed into the chamber of the inline sputtering apparatus using the same method as in Example 1. The same sputtering target materials as in Example 1 are used as the first sputtering target, the second sputtering target, the third sputtering target, and the fourth sputtering target. Then, with the sputtering gas pressure in the first chamber set to 1.6 Pa, a mixture of inert gas containing argon (Ar) and nitrogen ( _N2 ) and nitric oxide (NO) as a reactive gas (Ar: 18 sccm, _N2 : 13 sccm, NO: 4 sccm) is introduced. Then, a sputtering power of 8.2 kW is applied to the first sputtering target (molybdenum:silicon = 8:92) containing molybdenum and silicon, and molybdenum oxynitride containing molybdenum, silicon, oxygen and nitrogen is deposited on the main surface of the transparent substrate 20 by reactive sputtering, thereby forming a lower layer 32 with a thickness of 140 nm. Then, the opening of the main valve of the vacuum pump connected to the first chamber is adjusted to make the sputtering gas pressure in the first chamber 1.2 Pa. In addition, under the same conditions as the lower layer 32, an upper layer 31 with a thickness of 40 nm is formed on the lower layer 32 by reactive sputtering. A phase shift film 30 with a thickness of 180 nm is formed in this manner. After the phase shift film is formed on the transparent substrate, it is removed from the chamber, and the surface of the phase shift film is cleaned with pure water. The pure water cleaning conditions are set to a temperature of 30 degrees Celsius and a cleaning time of 60 seconds. Subsequently, an etching mask film 40 is formed using the same method as in Example 1. In this way, a phase-shifting photomask substrate 10 with a phase-shifting film 30 and an etching mask film 40 formed on a transparent substrate 20 is obtained.

The transmittance and phase difference of the phase-shifting film (after the surface of the phase-shifting film was washed with pure water) on the phase-shifting mask substrate 10 were measured using an MPM-100 manufactured by Lasertec. For the measurement of the transmittance and phase difference of the phase-shifting film, a substrate with a phase-shifting film 30 formed on the main surface of a synthetic quartz glass substrate (a dummy substrate) was used, placed on the same tray. Before forming the etching mask film, the substrate with the phase-shifting film (dummy substrate) was removed from the chamber, and the transmittance and phase difference of the phase-shifting film 30 were measured. The results showed a transmittance of 45% (wavelength: 405 nm), a phase difference of 188 degrees (wavelength: 405 nm), and a back reflectance of 0.7% (wavelength: 405 nm). Furthermore, similar to Embodiment 1, the optical properties of the upper layer 31 and the lower layer 32 of the phase shift film 30 were measured using a spectroscopic elliptic apparatus (M-2000D manufactured by J.A. Woollam Corporation). The refractive index of the upper layer 31 is 2.30, and the extinction coefficient is 0.17. Moreover, the refractive index of the lower layer 32 is 2.15, and the extinction coefficient is 0.11.

Furthermore, X-ray photoelectron spectroscopy (XPS) was used to analyze the composition of the obtained phase-shifting mask substrate in the depth direction. As a result, similar to Embodiment 1, in the phase-shifting film 30, except for the gradient composition region at the interface between the transparent substrate 20 and the phase-shifting film 30, and the gradient composition region at the interface between the phase-shifting film 30 and the etching mask film 40, the content of each constituent element is approximately fixed in the depth direction, with the atomic ratio of molybdenum to silicon being 1:8, falling within the range of 1:3 to 1:15. Moreover, in the upper layer 31, the content of each constituent element is: Mo 5 atomic%, Si 40 atomic%, N 47 atomic%, O 8 atomic%, and in the lower layer 32, Mo 5 atomic%, Si 40 atomic%, N 45 atomic%, O 10 atomic%. Furthermore, the combined content of oxygen and nitrogen, as light elements, is 55 atomic percent in the upper layer 31 and 55 atomic percent in the lower layer 32, both falling within the range of 50 atomic percent to 65 atomic percent. Next, a cross-sectional SEM observation was performed at 80,000x magnification at the center of the transferred pattern formation area on the obtained phase-shifting photomask substrate 10. The results confirmed that the phase-shifting film 30 has a columnar structure. That is, it was confirmed that the molybdenum silicate compound particles constituting the phase-shifting film 30 have a columnar particle structure extending towards the thickness direction of the phase-shifting film 30. Moreover, it was confirmed that the columnar particle structure of the phase-shifting film 30 is irregularly formed in the thickness direction, and the length of the columnar particles in the thickness direction is also inconsistent. Furthermore, it was also confirmed that the sparse portions of the phase-shifting film 30 are continuously formed in the thickness direction. Furthermore, it was confirmed that the average size of the columnar particles in the upper layer 31 of the phase shift film 30 is smaller than the average size of the columnar particles in the lower layer 32. The average size of the columnar particles in the upper layer 31 is 15 nm, and the average size of the columnar particles in the lower layer 32 is 25 nm.

B. Phase-shifting mask and its manufacturing method: Using the phase-shifting mask substrate manufactured as described above, a phase-shifting mask with a phase-shifting film pattern having an aperture of 1.5 μm is manufactured using the same method as in Example 1. To achieve a vertical cross-sectional shape and to form the desired micro-pattern, the phase-shifting film 30 is wet-etched with an etching time of 110%. The appropriate etching time in Example 2 is 0.07 times that in the comparative examples below, which significantly shortens the etching time.

The cross-section of the obtained phase-shifting mask was observed using a scanning electron microscope. The cross-sectional angle of the phase-shifting film pattern 30a of the phase-shifting mask is 75° or more, exhibiting a good cross-sectional shape. Furthermore, no immersion was observed at the interface with the etch mask pattern and the interface with the substrate in the phase-shifting film pattern. Therefore, a phase-shifting mask with excellent phase-shifting effect was obtained under exposure light containing wavelengths of 300 nm to 500 nm, and more specifically, under exposure light containing composite light including i-line, h-line, and g-line. In addition, the line edge roughness of the phase-shifting film pattern in the phase-shifting mask obtained in Example 2 was measured, and the result was less than 30 nm, meeting the required level. Furthermore, a cleaning test was conducted on the phase-shifting photomask substrate and the phase-shifting photomask obtained in Example 2, and the results showed that they met the required cleaning resistance. Therefore, it can be said that when the phase-shifting photomask of Example 2 is placed on the photomask stage of the exposure apparatus to expose and transfer the anti-corrosion film on the display device, it is possible to transfer fine patterns less than 2.0 μm with high precision.

In the phase shift film pattern 30a, the columnar structure of the phase shift film 30 is maintained. Furthermore, the surface of the transparent substrate 20 exposed after removing the phase shift film 30 is relatively smooth, and the decrease in transmittance caused by the surface roughness of the transparent substrate 20 can be ignored.

Furthermore, while the above embodiments described the use of molybdenum as a transition metal, the same effect is achieved when other transition metals are used. Also, the above embodiments described examples of a phase-shifting photomask substrate and a phase-shifting photomask for display device manufacturing, but are not limited to these. The phase-shifting photomask substrate and phase-shifting photomask of this invention can also be applied to semiconductor device manufacturing, MEMS (microelectromechanical system) manufacturing, printed circuit board manufacturing, etc. Furthermore, this invention can also be applied to binary photomask substrates having a light-shielding film as a thin film for pattern formation, or binary photomasks having a light-shielding film pattern. Furthermore, in the above embodiments, an example of a transparent substrate with dimensions of 1214 (1220 mm × 1400 mm × 13 mm) was described, but it is not limited to this. In the case of a phase-shifting photomask substrate for display device manufacturing, a large-size transparent substrate is used, wherein the length of one side of the transparent substrate is 300 mm or more. The size of the transparent substrate used for the phase-shifting photomask substrate for display device manufacturing is, for example, 330 mm × 450 mm or more and 2280 mm × 3130 mm or less. Furthermore, in the case of phase-shifting photomask substrates for semiconductor device manufacturing, MEMS manufacturing, and printed circuit board manufacturing, a small-size transparent substrate is used, wherein the length of one side of the transparent substrate is 9 inches or less. The transparent substrate used for the phase-shifting photomask substrate in the above-mentioned applications has dimensions of, for example, 63.1 mm × 63.1 mm or more and 228.6 mm × 228.6 mm or less. Typically, when manufacturing semiconductors or MEMS, the 6025 size (152 mm × 152 mm) or 5009 size (126.6 mm × 126.6 mm) is used, and when used as a printed circuit board, the 7012 size (177.4 mm × 177.4 mm) or 9012 size (228.6 mm × 228.6 mm) is used.

Comparative Example 1.A. Phase-Shifting Mask Substrate and its Manufacturing Method To manufacture the phase-shifting mask substrate of Comparative Example 1, a 1214-sized (1220 mm × 1400 mm) synthetic quartz glass substrate was prepared as a transparent substrate, similar to Example 1. Using the same method as in Example 1, the synthetic quartz glass substrate was placed into the chamber of the inline sputtering apparatus. Then, with the sputtering gas pressure in the first chamber set to 0.5 Pa, a mixture of argon (Ar) and nitrogen ( _N₂ ) gas (Ar: 30 sccm, _N₂ : 30 sccm) was introduced. Then, a sputtering power of 7.6 kW was applied to a first sputtering target containing molybdenum and silicon (molybdenum:silicon = 1:9) to deposit a molybdenum silicate nitride containing molybdenum, silicon, and nitrogen onto the main surface of the transparent substrate via reactive sputtering. A phase shift film with a thickness of 144 nm was thus formed. Subsequently, an etching mask film was formed using the same method as in Example 1. In this way, a phase shift mask substrate with a phase shift film and an etching mask film formed on the transparent substrate was obtained.

The transmittance and phase difference of the phase-shifting film on the obtained phase-shifting mask substrate were measured using an MPM-100 manufactured by Lasertec. In the measurement of the transmittance and phase difference of the phase-shifting film, a dummy substrate (a substrate with a phase-shifting film formed on the main surface of a synthetic quartz glass substrate) was used, prepared on the same tray. Before forming the etching mask film, the dummy substrate with the phase-shifting film was removed from the chamber, and the transmittance and phase difference of the phase-shifting film were measured. The results showed a transmittance of 29% (wavelength: 405 nm), a phase difference of 172 degrees (wavelength: 405 nm), and a back reflectance of 11% (wavelength: 405 nm).

Furthermore, X-ray photoelectron spectroscopy (XPS) was used to analyze the composition of the obtained phase-shifting mask substrate in the depth direction. The results showed that, except for the gradient composition regions at the interfaces between the transparent substrate 20 and the phase-shifting film 30, and between the phase-shifting film 30 and the etching mask film 40, the content of each constituent element in the phase-shifting film 30 remained approximately constant in the depth direction: Mo was 8 atomic%, Si was 39 atomic%, N was 52 atomic%, and O was 1 atomic%. The atomic ratio of molybdenum to silicon was 1:4.9, falling within the range of 1:3 to 1:15. The combined content of oxygen, nitrogen, and carbon, as light elements, was 53 atomic%, falling within the range of 50 to 65 atomic%.

Next, a cross-sectional SEM was performed at 80,000x magnification at the center of the area where the transfer pattern was formed on the phase-shifted photomask substrate 10. The results showed that no columnar structure could be identified in the phase-shifted film, confirming that it was an ultra-fine crystalline or amorphous structure.

B. Phase-shifting mask and its manufacturing method: Using the phase-shifting mask substrate manufactured as described above, the phase-shifting mask is manufactured using the same method as in Example 1. To achieve a vertical cross-sectional shape and to form the desired micro-pattern, wet etching is performed on the phase-shifting film at 110% of the etching time. The appropriate etching time in Comparative Example 1 is 142 minutes, which is relatively long. The surface of the transparent substrate 20 exposed after removing the phase-shifting film 30 is relatively rough and appears cloudy to the naked eye. Therefore, the decrease in transmittance due to the rough surface of the transparent substrate 20 is more significant. Therefore, it is anticipated that when the phase-shifted photomask of Comparative Example 1 is placed on the photomask stage of the exposure device to expose and transfer the anti-corrosion film on the display device, it will be impossible to transfer fine patterns smaller than 2.0 μm.

10: Phase-shifting mask substrate; 20: Transparent substrate; 30: Phase-shifting film; 30a: Phase-shifting film pattern; 31: Upper layer; 31a: Upper layer pattern; 32: Lower layer; 32a: Lower layer pattern; 40: Etching mask film; 40a: First etching mask film pattern; 40b: Second etching mask film pattern; 50: First anti-corrosion film pattern; 60: Second anti-corrosion film pattern; 100: Phase-shifting mask.

Figure 1 is a schematic diagram showing the film structure of the phase-shifting photomask substrate in Embodiment 1. Figure 2 is a schematic diagram showing the film structure of the phase-shifting photomask substrate in Embodiment 2. Figures 3(a) to (e) are schematic diagrams showing the manufacturing steps of the phase-shifting photomask in Embodiment 3. Figures 4(a) to (c) are schematic diagrams showing the manufacturing steps of the phase-shifting photomask in Embodiment 4.

10: Phase-shifted photomask substrate

20:Transparent substrate

30: Phase shifting film

31: Upper level

32: Lower level

40: Etching Mask

Claims (14)

A photomask substrate, characterized in that: it has a pattern-forming thin film on a transparent substrate, and the photomask substrate is a master substrate for forming a photomask with a transfer pattern on the transparent substrate by wet etching of the pattern-forming thin film; the pattern-forming thin film contains a transition metal and silicon; the pattern-forming thin film has a columnar structure; the pattern-forming thin film includes an upper layer and a lower layer; the average size of the particles constituting the columnar structure in the upper layer is smaller than the average size of the particles constituting the columnar structure in the lower layer. For example, in the photomask substrate of claim 1, the atomic ratio of the transition metal to silicon contained in the thin film for forming the above pattern is transition metal: silicon = 1:3 or more and 1:15 or less. The photomask substrate of claim 1 or 2, wherein the thin film for forming the above pattern contains at least nitrogen or oxygen. For example, the photomask substrate of claim 1 or 2, wherein the aforementioned transition metal is molybdenum. For the photomask substrate of claim 1 or 2, the thin film for forming the above pattern is a phase shift film having the following optical characteristics: a transmittance of 1% to 80% for the representative wavelength of the exposed light, and a phase difference of 160° to 200°. The photomask substrate of claim 1 or 2, wherein an etching mask film with etching selectivity different from that of the pattern forming film is provided on the aforementioned pattern forming film. The photomask substrate of claim 6, wherein the aforementioned etching mask film comprises a material containing chromium and substantially free of silicon. A method for manufacturing a photomask substrate, characterized in that: a pattern-forming thin film containing a transition metal and silicon is formed on a transparent substrate using a sputtering method; and regarding the pattern-forming thin film, a transition metal silicide target containing a transition metal and silicon is used in a film-forming chamber; the sputtering gas pressure in the film-forming chamber, to which sputtering gas is supplied, is 0.8 Pa or more and 3.0 Pa or less; the pattern-forming thin film comprises an upper layer and a lower layer; the sputtering gas pressure in the film-forming chamber during the formation of the upper layer is lower than the sputtering gas pressure in the film-forming chamber during the formation of the lower layer. As in the method for manufacturing the photomask substrate of claim 8, the atomic ratio of the transition metal to silicon in the aforementioned transition metal silicate target is transition metal: silicon = 1:3 or more and 1:15 or less. As in the method of manufacturing the photomask substrate of claim 8 or 9, an etching mask film is formed on the aforementioned pattern-forming film using a sputtering target containing a material having etching selectivity different from that of the pattern-forming film. The method for manufacturing the photomask substrate as described in claim 10, wherein the thin film for forming the pattern and the etching mask film are formed using a linear sputtering apparatus. A method for manufacturing a photomask, characterized by comprising the following steps: preparing a photomask substrate as described in any one of claims 1 to 5, or a photomask substrate manufactured using the method for manufacturing a photomask substrate as described in claims 8 or 9; and forming a resist film on the aforementioned pattern-forming thin film, using the resist film pattern formed from the aforementioned resist film as a mask to perform wet etching on the aforementioned pattern-forming thin film, thereby forming a transfer pattern on the aforementioned transparent substrate. A method for manufacturing a photomask, characterized by comprising the following steps: Preparing a photomask substrate as described in claim 6 or 7, or a photomask substrate manufactured using a method for manufacturing a photomask substrate as described in claim 10 or 11; Forming an etching resist film on the aforementioned etching mask film, using the etching resist film pattern formed from the aforementioned etching resist film as a mask to perform wet etching on the aforementioned etching mask film, thereby forming an etching mask film pattern on the aforementioned pattern forming film; Using the etching mask film pattern as a mask to perform wet etching on the aforementioned pattern forming film, thereby forming a transfer pattern on the aforementioned transparent substrate. A method for manufacturing a display device is characterized by including an exposure step in which a photomask obtained by means of the photomask manufacturing method of claim 12 or 13 is placed on a photomask stage of an exposure device, and the transfer pattern formed on the photomask is exposed and transferred to an anti-corrosion agent formed on a substrate of the display device.