JP7527992B2 - Photomask blank, photomask manufacturing method, and display device manufacturing method - Google Patents

Description

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

In recent years, display devices such as FPDs (Flat Panel Displays) typified by LCDs (Liquid Crystal Displays) have rapidly become larger in screen size and wider in viewing angle, while also becoming more precise and displaying at higher speeds. One of the elements required for this higher resolution and faster display is the creation of electronic circuit patterns such as fine elements and wiring with high dimensional accuracy. Photolithography is often used to pattern the electronic circuits for these display devices. For this reason, photomasks such as phase shift masks and binary masks, which have fine and highly accurate patterns, are required for the manufacture of display devices.

For example, Patent Document 1 discloses a phase shift mask blank having a phase shift film on a transparent substrate. In this mask blank, the phase shift film has a reflectance of 35% or less and a transmittance of 1% to 40% for exposure light of a composite wavelength including i-line (365 nm), h-line (405 nm), and g-line (436 nm), and is composed of a multilayer film of two or more layers made of a metal silicide compound containing at least one light element substance of oxygen (O), nitrogen (N), and carbon (C) so that the slope of the pattern cross section is formed sharply during pattern formation, and the metal silicide compound is formed by injecting a reactive gas containing the light element substance and an inert gas at a ratio of 0.5:9.5 to 4:6.
The metal silicide compound is characterized in that silicon (Si) is contained in at least one metal substance selected from aluminum (Al), cobalt (Co), tungsten (W), molybdenum (Mo), vanadium (V), palladium (Pd), titanium (Ti), platinum (Pt), manganese (Mn), iron (Fe), nickel (Ni), cadmium (Cd), zirconium (Zr), magnesium (Mg), lithium (Li), selenium (Se), copper (Cu), yttrium (Y), sulfur (S), indium (In), tin (Sn), boron (B), beryllium (Be), sodium (Na), tantalum (Ta), hafnium (Hf), and niobium (Nb), or the metal silicide further contains at least one light element substance selected from nitrogen (N), oxygen (O), carbon (C), boron (B), and hydrogen (H).

Korean Patent No. 1801101 Patent No. 3988041

In recent years, phase shift masks used in the manufacture of high-definition (1000 ppi or more) panels are required to have a fine phase shift film pattern with a hole diameter of 6 μm or less and a line width of 4 μm or less, in order to enable high-resolution pattern transfer. Specifically, a phase shift mask is required to have a fine phase shift film pattern with a hole diameter of 1.5 μm.
Furthermore, in order to achieve higher resolution pattern transfer, there is a demand for phase shift mask blanks having a phase shift film with a transmittance of 15% or more to the exposure light, and phase shift masks on which a phase shift film pattern with a transmittance of 15% or more to the exposure light is formed.
In order to satisfy the required transmittance for the exposure light, it is effective to increase the ratio of silicon in the atomic ratio of metal to silicon in the metal silicide compound (metal silicide material) constituting the phase shift film. However, this causes problems such as a significant slowdown in the wet etching rate (prolonged wet etching time), damage to the substrate by the wet etching solution, and a decrease in the transmittance of the transparent substrate.

Patent Document 2 discloses a halftone phase shift mask blank having a phase shifter film on a transparent substrate, the phase shifter film being made of a metal silicide compound containing molybdenum as a first metal component, one or more metals selected from tantalum, zirconium, chromium and tungsten as a second metal component, and one or more elements selected from oxygen, nitrogen and carbon. From the viewpoint of chemical resistance of the phase shifter film and processability during etching, it is disclosed that the ratio of the first metal component to the second metal component in the metal silicide compound is preferably first metal component:second metal component=100:1 to 2:1 (atomic ratio).
The phase shifter film disclosed in Patent Document 2 is intended to be patterned by dry etching when producing a phase shift mask. When this phase shifter film is patterned by wet etching, as described above, there are problems such as a slow wet etching rate of the phase shifter film, damage to the substrate by the wet etching solution, and a decrease in the transmittance of the transparent substrate.

The present invention has been made to solve the above-mentioned problems, and the object of the present invention is to provide a photomask blank, a photomask manufacturing method, and a display device manufacturing method that can reduce the wet etching time of a phase shift film containing metal and silicon in forming a transfer pattern on a photomask, suppress damage to the substrate, and form a transfer pattern that has a good cross-sectional shape, line edge roughness (LER), and good chemical resistance, even when the phase shift film has a high transmittance for the representative wavelength of exposure light.

The inventors have thoroughly investigated ways to solve these problems. First, in order to create a phase shift film with high transmittance for the representative wavelength of the exposure light (e.g., 313 nm to 436 nm), they focused on zirconium, which has a smaller extinction coefficient than molybdenum at the representative wavelength, and selected a MoZrSi-based material containing molybdenum, zirconium, silicon, and nitrogen as the material for the phase shift film.

It is known that MoZrSi-based materials are used as phase shift films in mask blanks for LSIs used in the manufacture of semiconductor devices. However, if the MoZrSi-based materials used in mask blanks for LSIs are applied directly to phase shift mask blanks for display device manufacture, it is found that wet etching of the phase shift film takes too much time, and damage to the substrate and a decrease in the transmittance of the transparent substrate cannot be sufficiently suppressed. Thus, even if the MoZrSi-based materials used in mask blanks for LSIs are simply applied to phase shift mask blanks for display device manufacture, it is not possible to obtain the desired phase shift mask blanks for display device manufacture.
It was also found that, depending on the composition ratio of the MoZrSi-based material, the phase shift film has poor chemical resistance and the desired cleaning resistance cannot be obtained, and the reflectance is too high, resulting in a deterioration in transfer characteristics.
Therefore, the present inventors have further conducted intensive research and found that it is effective to define the atomic ratio of molybdenum and zirconium and the content ratio of silicon to the total of molybdenum, zirconium and silicon as indicators in the MoZrSi-based material. That is, the inventors have found that the above problem can be solved by adjusting the atomic ratio of molybdenum and zirconium in the MoZrSi-based material and the content ratio of silicon to the total of molybdenum, zirconium and silicon in order to suppress the occurrence of damage to the transparent substrate caused by the wet etching solution when the phase shift film is patterned by wet etching, and to achieve a high wet etching rate of the phase shift film when the phase shift film is patterned. The present invention has been made as a result of the above intensive research and requires the following configuration.

(Configuration 1) A photomask blank having a phase shift film on a transparent substrate,
the photomask blank is a master for forming a photomask, the photomask having a phase shift film pattern obtained by wet etching the phase shift film on the transparent substrate,
the phase shift film is composed of a single layer or multiple layers, and 50% to 100% of the total thickness of the phase shift film is a MoZrSi-based material layer made of a material containing molybdenum (Mo), zirconium (Zr), silicon (Si) and nitrogen;
The MoZrSi-based material layer has an atomic ratio of molybdenum and zirconium of Mo:Zr=1.5:1 to 1:4 (1:0.67 to 1:4), and a silicon content ratio of the total of molybdenum, zirconium, and silicon is 70 to 88 atomic %.

(Configuration 2) The photomask blank according to configuration 1, characterized in that the phase shift film has optical properties of a transmittance of 20% or more and 80% or less for the representative wavelength of the exposure light, and a phase difference of 160° or more and 200° or less.

(Structure 3) The photomask blank according to structure 1 or 2, characterized in that the phase shift film is a laminated film including a lower layer on the transparent substrate side and an upper layer laminated on the lower layer, and the lower layer is the MoZrSi-based material layer.

(Configuration 4) The photomask blank according to configuration 3, characterized in that the upper layer is made of a material that has a smaller refractive index than the lower layer and a higher extinction coefficient at the representative wavelength of the exposure light.

(Configuration 5) The photomask blank of configuration 4, characterized in that the phase shift film has refractive indices, extinction coefficients, and film thicknesses of the upper and lower layers set so that the back reflectance for the representative wavelength of the exposure light is 15% or less.

(Structure 6) A photomask blank according to any one of structures 1 to 5, characterized in that an etching mask film having a different etching selectivity with respect to the phase shift film is provided on the phase shift film.

(Configuration 7) A process for preparing a photomask blank according to any one of configurations 1 to 5;
forming a resist film on the phase shift film, and wet-etching the phase shift film using a resist film pattern formed from the resist film as a mask to form a phase shift film pattern on the transparent substrate.

(Configuration 8) A method for manufacturing a photomask blank according to configuration 6, comprising the steps of:
forming a resist film on the etching mask film, and wet-etching the etching mask film using a resist film pattern formed from the resist film as a mask to form an etching mask film pattern on the phase shift film;
and wet-etching the phase shift film using the etching mask film pattern as a mask to form a phase shift film pattern on the transparent substrate.

(Configuration 9) A method for manufacturing a display device, comprising an exposure step of placing a photomask obtained by the photomask manufacturing method described in configuration 7 or 8 on a mask stage of an exposure device, and exposing and transferring a transfer pattern including the phase shift film pattern formed on the photomask to a resist formed on a display device substrate.

The photomask blank according to the present invention can reduce the wet etching time of the phase shift film containing metal and silicon in forming a transfer pattern of the photomask, even when the phase shift film has a high transmittance for the representative wavelength of the exposure light, and can provide a photomask blank capable of forming a transfer pattern having a good cross-sectional shape, line edge roughness, and chemical resistance.

According to the photomask manufacturing method of the present invention, a photomask is manufactured using the above photomask blank. Therefore, even if the phase shift film has a high transmittance for the representative wavelength of the exposure light, the wet etching rate of the phase shift film is fast, and there is no decrease in the transmittance of the transparent substrate caused by damage to the transparent substrate by the wet etching solution, and a photomask can be manufactured that has a transfer pattern (phase shift film pattern) with good transfer accuracy, line edge roughness, and chemical resistance. This photomask can accommodate line and space patterns and fine contact holes.

In addition, according to the manufacturing method of the display device of the present invention, a display device is manufactured using a photomask obtained by the above-mentioned photomask manufacturing method. Therefore, it is possible to manufacture a display device having a fine line-and-space pattern and contact holes.

1 is a schematic diagram showing a film configuration (transparent substrate/phase shift film) of a phase shift mask blank according to a first embodiment. FIG. 1 is a schematic diagram showing the film structure (transparent substrate/phase shift film/etching mask film) of a phase shift mask blank according to a second embodiment. FIG. 11A to 11C are schematic diagrams showing a manufacturing process of a phase shift mask according to a third embodiment. 13A to 13C are schematic diagrams showing a manufacturing process of a phase shift mask according to a fourth embodiment.

Embodiment 1.2.
In the first and second embodiments, a phase shift mask blank (photomask blank) will be described. The phase shift mask blank of the first embodiment is an original plate for forming a phase shift mask (photomask), and this phase shift mask is a phase shift mask having a transfer pattern on a transparent substrate, including a phase shift film pattern obtained by wet etching a phase shift film using an etching mask film pattern in which a desired pattern is formed on the etching mask film as a mask. The phase shift mask blank of the second embodiment is an original plate for forming a phase shift mask, and this phase shift mask is a phase shift mask having a transfer pattern on a transparent substrate, including a phase shift film pattern obtained by wet etching a phase shift film using a resist film pattern in which a desired pattern is formed on the resist film as a mask. The transfer pattern in this specification is obtained by patterning at least one optical film formed on a transparent substrate. The optical film can be a phase shift film or an etching mask film, and may further include other films (such as a light-shielding film, a film for suppressing reflection, and a conductive film). That is, the transfer pattern can include a patterned phase shift film or an etching mask film, and may further include other patterned films.

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

The transparent substrate 20 is transparent to the exposure light. The transparent substrate 20 has a transmittance of 85% or more, preferably 90% or more, to the exposure light when there is no surface reflection loss. 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, soda lime glass, and low thermal expansion glass (SiO ₂ -TiO ₂ glass, etc.). When the transparent substrate 20 is made of low thermal expansion glass, the position change of the phase shift film pattern caused by the thermal deformation of the transparent substrate 20 can be suppressed. In addition, the transparent substrate 20 used for display device applications is generally a rectangular substrate, and the length of the short side of the transparent substrate is 300 mm or more. The phase shift mask blank 10 of the present invention is a phase shift mask blank 10 that can provide a phase shift mask 100 that can stably transfer a fine phase shift film pattern (e.g., width or diameter dimensions of less than 2.0 μm) formed on a transparent substrate 20, even if the transparent substrate 20 has a large size in which the short side length is 300 mm or more.

The phase shift film 30 is made of a single layer or multiple layers, and 50% to 100% of the total thickness of the phase shift film 30 is made of a MoZrSi-based material containing molybdenum (Mo), zirconium (Zr), silicon (Si), and nitrogen. The MoZrSi-based material may further contain transition metals such as tantalum (Ta), tungsten (W), and titanium (Ti).
In addition, the phase shift film 30 may be made of a material other than the MoZrSi-based material, so long as the transmittance and phase difference for the representative wavelength of the exposure light are predetermined values, and the portion of the phase shift film 30 that is 50% or less of the total thickness of the phase shift film 30 may be made of a material other than the MoZrSi-based material. In this case, a metal silicide-based material containing metal and silicon that can be etched with the same wet etching solution as the MoZrSi-based material is preferable. For example, metal silicide-based materials other than MoZrSi-based materials include molybdenum silicide-based materials (MoSi-based materials), zirconium silicide-based materials (ZrSi-based materials), tantalum silicide-based materials (TaSi-based materials), tungsten silicide-based materials (WSi-based materials), and titanium silicide-based materials (TiSi-based materials). The MoSi-based materials, ZrSi-based materials, TaSi-based materials, WSi-based materials, and TiSi-based materials may contain elements such as nitrogen, oxygen, and carbon.
In the MoZrSi-based material layer, the atomic ratio of molybdenum to zirconium is Mo:Zr=1.5:1 to 1:4, that is, Mo:Zr=1:0.67 to 1:4. In the case of a MoZrSi-based material layer in which the ratio of Zr is smaller than the range of the atomic ratio of Mo:Zr, the wet etching rate with respect to the wet etching solution is slow, so that damage to the transparent substrate is likely to occur. In addition, it is difficult to obtain a phase shift film having a high transmittance to the representative wavelength of the exposure light. In addition, in the case of a MoZrSi-based material layer in which the ratio of Zr is larger than the range of the atomic ratio of Mo:Zr, it is easy to obtain a phase shift film 30 having a high transmittance (for example, 20% or more and 80% or less) to the representative wavelength of the exposure light, but the chemical resistance (cleaning resistance) is insufficient, and it is not preferable from the viewpoint of defective quality occurring during film formation. The atomic ratio of molybdenum to zirconium is preferably Mo:Zr=1:0.8 to 1:3, and more preferably Mo:Zr=1:1 to 1:2.

In addition, in the MoZrSi-based material layer, the content ratio of silicon to the total of molybdenum, zirconium, and silicon (Si/[Mo+Zr+Si]) is preferably Si/[Mo+Zr+Si]=70 to 88 atomic %. If Si/[Mo+Zr+Si] is less than 70 atomic %, it is difficult to realize a phase shift film 30 having high transmittance (for example, 20% to 80%) and chemical resistance to the representative wavelength of the exposure light. If Si/[Mo+Zr+Si] is more than 88 atomic %, the wet etching rate with respect to the wet etching solution is slow, so that damage to the transparent substrate 20 is likely to occur, and the transmittance is likely to decrease due to roughness of the transparent substrate 20. The content ratio of silicon to the total of molybdenum, zirconium and silicon is preferably Si/[Mo+Zr+Si]=72 to 86 atomic %, and more preferably Si/[Mo+Zr+Si]=75 to 85 atomic %.
This phase shift film 30 can be formed by a sputtering method.
In the MoZrSi-based material layer of the phase shift film 30 in this embodiment, the atomic ratio of molybdenum to zirconium and the content ratio of silicon to the total of molybdenum, zirconium, and silicon satisfy the above-mentioned ranges, so that the film can be formed at a good vacuum level of 0.5 Pa or less, the overetching time can be shortened to suppress damage to the transparent substrate 20, and a phase shift film pattern 30a having a good cross-sectional shape and LER and good chemical resistance can be formed.

The phase shift film 30 may have a columnar structure. This columnar structure can be confirmed by cross-sectional SEM observation of the phase shift film 30. That is, the columnar structure in the present invention refers to a state in which the particles of the transition metal silicide compound containing molybdenum, zirconium, and silicon that constitute the phase shift film 30 have a columnar particle structure that extends toward the film thickness direction of the phase shift film 30 (the direction in which the above particles are deposited). A phase shift film 30 having this columnar structure is preferable in that it is easier to obtain a high transmittance.

In addition to the nitrogen mentioned above, the phase shift film 30 may contain oxygen to adjust the transmittance, and may also contain other elements such as helium and carbon to reduce film stress and control the wet etching rate.

The transmittance of the phase shift film 30 for the exposure light satisfies the value required for the phase shift film 30. The transmittance of the phase shift film 30 for the light of a predetermined wavelength (representative wavelength) contained in the exposure light is preferably 20% or more and 80% or less, more preferably 25% or more and 75% or less, and even more preferably 30% or more and 70% or less. That is, when the exposure light is a composite light including light in a wavelength range of 313 nm or more and 436 nm or less, the phase shift film 30 has the above-mentioned transmittance for light of a representative wavelength included in that wavelength range. For example, when the exposure light is a composite light including i-line, h-line, and g-line, the phase shift film 30 has the above-mentioned transmittance for any of i-line, h-line, and g-line.
The transmittance can be measured using a phase shift amount measuring device or the like.

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

The phase shift film 30 may also be a laminated film including a lower layer on the transparent substrate side and an upper layer laminated on the lower layer. When the phase shift film 30 is a laminated film including a lower layer and an upper layer, it is preferable that the lower layer is the MoZrSi-based material layer from the viewpoints of reducing the defective quality of the phase shift film 30, suppressing damage to the transparent substrate 20 by a wet etching solution, and improving the pattern cross-sectional shape when the phase shift film 30 is patterned by wet etching. The upper layer in the phase shift film 30 may be the same MoZrSi-based material layer as the lower layer, or may be different. When the upper layer is made of a different material from the lower layer, a metal silicide-based material that can be etched with the same wet etching solution as the MoZrSi-based material, such as a MoSi-based material, a ZrSi-based material, a TaSi-based material, a WSi-based material, or a TiSi-based material, can be used.

In addition, by selecting a material for the upper layer of the phase shift film 30 that is smaller than the refractive index n at the representative wavelength (e.g., 313 nm to 436 nm) of the exposure light in the lower layer and that is higher than the extinction coefficient k, the back surface reflectance of the phase shift film 30 on the side where the exposure light is incident can be reduced.
Specifically, the refractive index, extinction coefficient, and film thickness of the upper layer and the lower layer are set so that the back surface reflectance for the representative wavelength of the exposure light is 15% or less. It is preferable that the back surface reflectance of the phase shift film 30 for the representative wavelength of the exposure light is 10% or less.

The etching mask film 40 is disposed on the upper side of the phase shift film 30 and is made of a material having etching resistance against the etching solution that etches the phase shift film 30 (having a different etching selectivity from the phase shift film 30). The etching mask film 40 may have a function of blocking the transmission of the exposure light, or may have a function of reducing the film surface reflectance of the phase shift film 30 to light incident from the phase shift film 30 side so that the film surface reflectance of the phase shift film 30 is 15% or less in the wavelength range of 313 nm to 436 nm. The etching mask film 40 is made of a chromium-based material containing chromium (Cr). More specifically, the chromium-based material may be chromium (Cr) or a material containing chromium (Cr) and at least one of oxygen (O), nitrogen (N), and carbon (C). Alternatively, a material containing chromium (Cr) and at least one of oxygen (O), nitrogen (N), and carbon (C) and further containing fluorine (F) may be used. For example, materials that can be used to form the etching mask film 40 include Cr, CrO, CrN, CrF, CrCO, CrCN, CrON, CrCON, and CrCONF.
The etching mask film 40 can be formed by a sputtering method.

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

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

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

Next, a description will be given of a method for manufacturing phase shift mask blank 10 according to the first and second embodiments. Phase shift mask blank 10 shown in Fig. 1 is manufactured by carrying out the following phase shift film forming step and etching mask film forming step. Phase shift mask blank 10 shown in Fig. 2 is manufactured by the phase shift film forming step.
Each step will be described in detail below.

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

Next, the phase shift film 30 is formed on the transparent substrate 20 by sputtering.
The phase shift film 30 is formed using a MoZrSi-based target containing molybdenum (Mo), zirconium (Zr), and silicon (Si) which are the main components of the material constituting the phase shift film 30, or a MoZrSiO-based target, MoZrSiN-based target, or MoZrSiON-based target containing molybdenum (Mo), zirconium (Zr), silicon (Si), oxygen (O) and/or nitrogen (N) as a sputtering target, in a sputtering gas atmosphere containing at least one inert gas selected from the group consisting of helium gas, neon gas, argon gas, krypton gas, and xenon gas, or in a sputtering gas atmosphere containing a mixed gas of the above-mentioned inert gas and an active gas containing at least nitrogen selected from the group consisting of oxygen gas, nitrogen gas, carbon dioxide gas, nitric oxide gas, and nitrogen dioxide gas. The Mo, Zr, and Si in the MoZrSi-based target, MoZrSiO-based target, MoZrSiN-based target, and MoZrSiON-based target are adjusted so that the atomic ratio of molybdenum and zirconium in the MoZrSi-based material layer formed by sputtering is Mo:Zr=1.5:1 to 1:4 (1:0.67 to 1:4), and the content ratio of silicon to the total of molybdenum, zirconium, and silicon is 70 to 88 atomic %. The phase shift film 30 may be formed using a Mo target, a Zr target, and a Si target, or a MoSi target and a ZrSi target, so as to satisfy the above-mentioned atomic ratio and content ratio of Mo, Zr, and Si.

The composition and thickness of the phase shift film 30 are adjusted so that the phase shift film 30 has the above-mentioned phase difference and transmittance. The composition of the phase shift film 30 can be controlled by the content ratio of the elements constituting the sputtering target (e.g., the content ratio of Mo, Zr, and Si), the composition and flow rate of the sputtering gas, etc. The thickness of the phase shift film 30 can be controlled by the sputtering power, sputtering time, etc. In addition, it is preferable to form the phase shift film 30 using an in-line type sputtering device. When the sputtering device is an in-line type sputtering device, the thickness of the phase shift film 30 can also be controlled by the transport speed of the transparent substrate 20.

When the phase shift film 30 is made of a single film, the above-mentioned film formation process is performed only once while changing the composition and flow rate of the sputtering gas with the elapsed time of the film formation process. When the phase shift film 30 is made of multiple films with different compositions, the above-mentioned film formation process is performed multiple times while changing the composition and flow rate of the sputtering gas for each film formation process. The phase shift film 30 may be formed using a target having a different content ratio of the elements that make up the sputtering target. When the film formation process is performed multiple times, the sputtering power applied to the sputtering target can be reduced.
In this manner, there is obtained phase shift mask blank 10 according to embodiment 2. In manufacturing phase shift mask blank 10 according to embodiment 1, the following etching mask film forming step is further carried out.

3. Etching Mask Film Formation Step After performing a surface treatment to adjust the surface oxidation state of the phase shift film 30 as necessary, the etching mask film 40 is formed on the phase shift film 30 by a sputtering method. The etching mask film 40 is preferably formed using an in-line type sputtering device. When the sputtering device is an in-line type sputtering device, the thickness of the etching mask film 40 can also be controlled by the transport speed of the transparent substrate 20.
The etching mask film 40 is formed by using a sputtering target containing chromium or a chromium compound (chromium oxide, chromium nitride, chromium carbide, chromium oxynitride, chromium oxynitride carbide, etc.) in a sputtering gas atmosphere containing at least one inert gas selected from the group consisting of helium gas, neon gas, argon gas, krypton gas, and xenon gas, or in a sputtering gas atmosphere containing a mixed gas of an inert gas containing at least one selected from the group consisting of helium gas, neon gas, argon gas, krypton gas, and xenon gas and an active gas containing at least one selected from the group consisting of oxygen gas, nitrogen gas, nitric oxide gas, nitrogen dioxide gas, carbon dioxide gas, a hydrocarbon gas, and a fluorine gas. Examples of the hydrocarbon gas include methane gas, butane gas, propane gas, and styrene gas.

When the etching mask film 40 is a single film with a uniform composition, the above-mentioned film formation process is performed only once without changing the composition and flow rate of the sputtering gas. When the etching mask film 40 is a multiple film with different compositions, the above-mentioned film formation process is performed multiple times by changing the composition and flow rate of the sputtering gas for each film formation process. When the etching mask film 40 is a single film with a composition that changes continuously in the thickness direction, the above-mentioned film formation process is performed only once while changing the composition and flow rate of the sputtering gas with the elapsed time of the film formation process.
In this manner, phase shift mask blank 10 of the first embodiment is obtained.

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

The phase shift mask blank 10 of the first and second embodiments has a good cross-sectional shape due to wet etching, and a phase shift film pattern 30a with high transmittance can be formed in a short etching time. Therefore, a phase shift mask blank 10 is obtained that can manufacture a phase shift mask 100 that can accurately transfer a high-definition phase shift film pattern 30a without a decrease in the transmittance of the transparent substrate 20 caused by damage to the transparent substrate 20 by the wet etching solution.

Embodiment 3.4.
In the third and fourth embodiments, a method for manufacturing phase shift mask 100 will be described.

3A and 3B are schematic diagrams showing a method for manufacturing phase shift mask 100 according to a third embodiment. FIG. 4 is a schematic diagram showing a method for manufacturing phase shift mask 100 according to a fourth embodiment.
The method for manufacturing the phase shift mask 100 shown in Fig. 3 is a method for manufacturing the phase shift mask 100 using the phase shift mask blank 10 shown in Fig. 1, and includes the following steps: forming a resist film on the etching mask film 40 of the phase shift mask blank 10; forming a resist film pattern 50 by drawing and developing a desired pattern on the resist film (first resist film pattern forming step); wet-etching the etching mask film 40 using the resist film pattern 50 as a mask to form an etching mask film pattern 40a on the phase shift film 30 (first etching mask film pattern forming step); and wet-etching the phase shift film 30 using the etching mask film pattern 40a as a mask to form a phase shift film pattern 30a on the transparent substrate 20 (phase shift film pattern forming step). The method further includes a second resist film pattern forming step and a second etching mask film pattern forming step.

The manufacturing method of phase shift mask 100 shown in Figure 4 is a method of manufacturing phase shift mask 100 using phase shift mask blank 10 shown in Figure 2, and includes the following steps of forming a resist film on phase shift mask blank 10, drawing and developing a desired pattern on the resist film to form resist film pattern 50 (first resist film pattern formation step), and wet-etching phase shift film 30 using resist film pattern 50 as a mask to form phase shift film pattern 30a on transparent substrate 20 (phase shift film pattern formation step).
Each step of the manufacturing process for phase shift mask 100 according to the third and fourth embodiments will be described in detail below.

Manufacturing Process of Phase Shift Mask 100 According to Third Embodiment 1. First Resist Film Pattern Forming Step In the first resist film pattern forming step, a resist film is first formed on etching mask film 40 of phase shift mask blank 10 of the first embodiment. There are no particular limitations on the resist film material used. For example, it may be any material that is sensitive to laser light having a wavelength selected from the wavelength range of 350 nm to 436 nm described later. The resist film may be either positive type or negative type.
Thereafter, a desired pattern is drawn on the resist film using a laser beam having a wavelength selected from the wavelength range of 350 nm to 436 nm. The pattern drawn on the resist film is a pattern to be formed on the phase shift film 30. Examples of the pattern drawn on the resist film include a line and space pattern and a hole pattern.
Thereafter, the resist film is developed with a predetermined developer to form a first resist film pattern 50 on the etching mask film 40, as shown in FIG. 3(a).

2. First Etching Mask Film Pattern Formation Step In the first etching mask film pattern formation step, first, the etching mask film 40 is etched using the first resist film pattern 50 as a mask to form a first etching mask film pattern 40a. The etching mask film 40 is formed from a chromium-based material containing chromium (Cr). The etching solution for etching the etching mask film 40 is not particularly limited as long as it can selectively etch the etching mask film 40. Specifically, an etching solution containing ceric ammonium nitrate and perchloric acid can be used.
Thereafter, the first resist film pattern 50 is stripped off using a resist stripper or by ashing, as shown in Fig. 3(b). In some cases, the next phase shift film pattern forming step may be performed without stripping off the first resist film pattern 50.

3. Phase shift film pattern forming process In the first phase shift film pattern forming process, the phase shift film 30 is wet-etched using the first etching mask film pattern 40a as a mask to form a phase shift film pattern 30a as shown in FIG. 3(c). The phase shift film pattern 30a may be a line and space pattern or a hole pattern. The etching solution for etching the phase shift film 30 is not particularly limited as long as it can selectively etch the phase shift film 30. For example, an etching solution containing ammonium fluoride, phosphoric acid, and hydrogen peroxide, or an etching solution containing ammonium hydrogen fluoride and hydrogen peroxide may be used.
In order to improve the cross-sectional shape of the phase shift film pattern 30a, the wet etching is preferably performed for a time (over-etching time) longer than the time (just-etching time) until the transparent substrate 20 is exposed in the phase shift film pattern 30a. Considering the influence on the transparent substrate 20, the over-etching time is preferably set to within the just-etching time plus 10 to 20% of the just-etching time.

4. Second Resist Film Pattern Formation Step In the second resist film pattern formation step, first, a resist film is formed to cover the first etching mask film pattern 40a. The resist film material used is not particularly limited. For example, it may be any material that is sensitive to laser light having a wavelength selected from the wavelength range of 350 nm to 436 nm described later. The resist film may be either positive or negative.
Then, a desired pattern is drawn on the resist film using a laser beam having a wavelength selected from the wavelength range of 350 nm to 436 nm. The pattern drawn on the resist film may be a light-shielding band pattern that shields the outer peripheral region of the region where the phase shift film pattern 30a is formed, a light-shielding band pattern that shields the center of the phase shift film pattern 30a, or the like. Depending on the transmittance of the phase shift film 30 to the exposure light, the pattern drawn on the resist film may not have a light-shielding band pattern that shields the center of the phase shift film pattern 30a.
Thereafter, the resist film is developed with a predetermined developer to form a second resist film pattern 60 on the first etching mask film pattern 40a, as shown in FIG. 3(d).

5. Second Etching Mask Film Pattern Formation Step In the second etching mask film pattern formation step, the first etching mask film pattern 40a is etched using the second resist film pattern 60 as a mask to form a second etching mask film pattern 40b as shown in FIG. 3(e). The first etching mask film pattern 40a is formed from a chromium-based material containing chromium (Cr). The etching solution for etching the first etching mask film pattern 40a is not particularly limited as long as it can selectively etch the first etching mask film pattern 40a. For example, an etching solution containing ceric ammonium nitrate and perchloric acid can be used.
Thereafter, the second resist film pattern 60 is stripped using a resist stripper or by ashing.
In this manner, phase shift mask 100 is obtained. That is, the transfer pattern of phase shift mask 100 according to the third embodiment can include phase shift film pattern 30a and second etching mask film pattern 40b.
In the above description, the etching mask film 40 has a function of blocking the transmission of exposure light. However, in the case where the etching mask film 40 only has a function of a hard mask when etching the phase shift film 30, the second resist film pattern forming process and the second etching mask film pattern forming process are not performed in the above description, and after the phase shift film pattern forming process, the first etching mask film pattern is peeled off to produce the phase shift mask 100. That is, the transfer pattern of the phase shift mask 100 according to the third embodiment may be composed of only the phase shift film pattern 30a. The transfer pattern may further include other film patterns. Examples of other films include a film that suppresses reflection, a conductive film, and the like.

According to the manufacturing method of the phase shift mask 100 of the third embodiment, since the phase shift mask blank 10 of the first embodiment is used, there is no decrease in the transmittance of the transparent substrate 20 due to damage to the transparent substrate 20 by the wet etching solution, the etching time can be shortened, and a phase shift film pattern 30a having a good cross-sectional shape, line edge roughness, and chemical resistance can be formed. Therefore, a phase shift mask 100 capable of transferring a high-definition phase shift film pattern 30a with high accuracy can be manufactured. The phase shift mask 100 manufactured in this manner can accommodate miniaturization of line and space patterns and contact holes.

Manufacturing process of phase shift mask 100 according to embodiment 4 1. Resist film pattern forming process In the resist film pattern forming process, a resist film is first formed on phase shift film 30 of phase shift mask blank 10 of embodiment 2. The resist film material used is the same as that described in embodiment 3. If necessary, before forming the resist film, a surface modification process may be performed on phase shift film 30 to improve adhesion with phase shift film 30. As described above, after forming the resist film, a desired pattern is drawn on the resist film using a laser beam having a wavelength selected from the wavelength range of 350 nm to 436 nm. Thereafter, the resist film is developed with a predetermined developer to form a resist film pattern 50 on phase shift film 30 as shown in FIG. 4(a).
2. Phase shift film pattern forming process In the phase shift film pattern forming process, the phase shift film 30 is etched using the resist film pattern as a mask to form a phase shift film pattern 30a as shown in FIG. 4(b). This forms a transfer pattern. The phase shift film pattern 30a and the etching solution for etching the phase shift film 30 and the overetching time are the same as those described in the third embodiment.
Thereafter, the resist film pattern 50 is stripped using a resist stripper or by ashing (FIG. 4C).
In this manner, phase shift mask 100 is obtained. The transfer pattern of the phase shift mask according to the present embodiment is composed of only phase shift film pattern 30a, but may further include other film patterns. Examples of other films include a film for suppressing reflection, a conductive film, and the like.
According to the method for manufacturing phase shift mask 100 of the fourth embodiment, since phase shift mask blank 10 of the second embodiment is used, there is no decrease in the transmittance of transparent substrate 20 caused by damage to transparent substrate 20 by a wet etching solution, the etching time can be shortened, and phase shift film pattern 30a having good cross-sectional shape, line edge roughness, and chemical resistance can be formed. Therefore, phase shift mask 100 capable of transferring high-definition phase shift film pattern 30a with good accuracy can be manufactured. Phase shift mask 100 manufactured in this manner can accommodate miniaturization of line and space patterns and contact holes.

Embodiment 5.
In the fifth embodiment, a method for manufacturing a display device will be described. The display device is manufactured by carrying out a step (mask mounting step) using phase shift mask 100 manufactured using phase shift mask blank 10 described above or by the method for manufacturing phase shift mask 100 described above, and a step (exposure step) of exposing and transferring a transfer pattern including phase shift film pattern 30a to a resist film on a display device substrate.
Each step will be described in detail below.

In the placing step, phase shift mask 100 manufactured in the third or fourth embodiment is placed on a mask stage of an exposure tool. Here, phase shift mask 100 is disposed so as to face a resist film formed on a display device substrate via a projection optical system of the exposure tool.

2. Pattern Transfer Process In the pattern transfer process, the phase shift mask 100 is irradiated with exposure light to transfer a transfer pattern including the phase shift film pattern 30a to a resist film formed on a display device substrate. The exposure light is a composite light including a plurality of wavelengths selected from the wavelength range of 365 nm to 436 nm, or a monochromatic light selected by cutting a certain wavelength range from the wavelength range of 365 nm to 436 nm using a filter or the like. For example, the exposure light is a composite light including at least one of i-line, h-line, and g-line, or a monochromatic light of i-line. When the composite light is used as the exposure light, the exposure light intensity can be increased to increase the throughput, thereby reducing the manufacturing cost of the display device.

The manufacturing method of the display device according to the fifth embodiment makes it possible to manufacture a high-definition display device having high resolution, fine line and space patterns, and contact holes.

Example 1. A. Phase Shift Mask Blank To manufacture phase shift mask blank 10 of Example 1, first, a synthetic quartz glass substrate having a size of 1214 (1220 mm×1400 mm) was prepared as transparent substrate 20 .

Thereafter, the synthetic quartz glass substrate was placed on a tray (not shown) with one of its main surfaces facing downward, and was then carried into the chamber of an in-line sputtering apparatus.
In order to form a phase shift film 30 on the other main surface of the transparent substrate 20, a mixed gas consisting of argon (Ar) gas and nitrogen (N ₂ ) gas was first introduced into the first chamber with the sputtering gas pressure set to 0.5 Pa. Then, using a MoZrSi target with an atomic ratio of Mo, Zr, and Si of Mo:Zr:Si=10:10:80, a MoZrSiN-based phase shift film 30 containing molybdenum, zirconium, silicon, and nitrogen was formed to a thickness of 143 nm on the main surface of the transparent substrate 20 by reactive sputtering. Note that the atomic ratio in the above target for sputtering is an example, and can be appropriately selected according to the desired composition of the phase shift film 30.

Next, the transparent substrate 20 with the phase shift film 30 was carried into the second chamber, and a mixed gas of argon (Ar) gas and nitrogen (N ₂ ) gas was introduced into the second chamber, and chromium nitride (CrN) containing chromium and nitrogen was formed on the phase shift film 30 by reactive sputtering (film thickness 15 nm). Next, a mixed gas of argon (Ar) gas and methane gas was introduced into the third chamber at a predetermined vacuum level, and chromium carbide (CrC) containing chromium and carbon was formed on the CrN by reactive sputtering (film thickness 60 nm). Finally, a mixed gas of argon (Ar) gas and methane gas, nitrogen (N ₂ ) gas, and oxygen (O ₂ ) gas was introduced into the fourth chamber at a predetermined vacuum level, and chromium carbonitride (CrCON) containing chromium, carbon, oxygen, and nitrogen was formed on the CrC by reactive sputtering (film thickness 30 nm). As described above, the etching mask film 40 having a laminated structure of a CrN layer, a CrC layer, and a CrCON layer was formed on the phase shift film 30 .
In this manner, a phase shift mask blank 10 in which a phase shift film 30 and an etching mask film 40 are formed on a transparent substrate 20 is obtained.

The refractive index and extinction coefficient of the phase shift film 30 of the obtained phase shift mask blank 10 were measured using a phase shift film-coated substrate (dummy substrate) in which a phase shift film 30 was formed on the main surface of a synthetic quartz glass substrate, which was set on the same tray and prepared.
As a result, the refractive index n of the MoZrSiN-based phase shift film was 2.45 (wavelength 405 nm) and the extinction coefficient k was 0.11 (wavelength 405 nm).
The transmittance and phase difference of the surface of the phase shift film 30 of the obtained phase shift mask blank 10 were measured by MPM-100 manufactured by Lasertec Corporation. The transmittance and phase difference of the phase shift film 30 were measured using a phase shift film-attached substrate (dummy substrate) in which the phase shift film 30 was formed on the main surface of a synthetic quartz glass substrate, which was prepared by setting the substrate on the same tray as described above. The transmittance and phase difference of the phase shift film 30 were measured by removing the phase shift film-attached substrate (dummy substrate) from the chamber before forming the etching mask film 40. As a result, the transmittance was 50% (wavelength: 405 nm), the phase difference was 180° (wavelength: 405 nm), the back reflectance was 15.4% (wavelength: 405 nm), and the front reflectance was 21.3% (wavelength 405 nm).

Further, the phase shift film 30 of the obtained phase shift mask blank 10 was subjected to a composition analysis in the depth direction by X-ray photoelectron spectroscopy (XPS).
In the composition analysis of the phase shift mask blank 10 in the depth direction by XPS, the phase shift film 30 had a substantially constant content of each element in the depth direction, except for the composition gradient region at the interface between the transparent substrate 20 and the phase shift film 30 and the composition gradient region at the interface between the phase shift film 30 and the etching mask film 40, and the content was 3 atomic % Mo, 5 atomic % Zr, 42 atomic % Si, 47 atomic % N, and 3 atomic % O. The atomic ratio of molybdenum to zirconium was 1:1, and was in the range of Mo:Zr=1:0.67 to 1:4. The content ratio of silicon to the total of molybdenum, zirconium, and silicon was 84 atomic %, and was in the range of [Si/(Mo+Zr+Si)]=70 to 88 atomic %. The oxygen contained in the phase shift film 30 is considered to be due to the presence of a small amount of oxygen in the chamber during film formation.

B. Phase Shift Mask and Its Manufacturing Method In order to manufacture phase shift mask 100 using phase shift mask blank 10 manufactured as described above, first, a photoresist film was applied onto etching mask film 40 of phase shift mask blank 10 using a resist coating apparatus.
Thereafter, a heating and cooling process was performed to form a photoresist film having a thickness of 520 nm.
Thereafter, a photoresist film was drawn using a laser drawing device, and after a developing and rinsing process, a resist film pattern with a hole pattern having a hole diameter of 1.5 μm was formed on the etching mask film.

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

Thereafter, using the first etching mask film pattern 40a as a mask, the phase shift film 30 was wet-etched with a molybdenum silicide etching solution prepared by diluting a mixed solution of ammonium hydrogen fluoride and hydrogen peroxide with pure water to form a phase shift film pattern 30a. This wet etching was performed with an overetching time of 10% in order to make the cross-sectional shape vertical and to form a required fine pattern.
Thereafter, the resist film pattern was peeled off.

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

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

In this way, a phase shift mask 100 was obtained in which a phase shift film pattern 30a with a hole diameter of 1.5 μm and a light shielding band consisting of a laminated structure of the phase shift film pattern 30a and the etching mask film pattern 40b were formed in the transfer pattern formation area on the transparent substrate 20.

The cross section of the obtained phase shift mask was observed by a scanning electron microscope. In the cross section, the angle between the edge of the phase shift film pattern 30a of the phase shift mask and the main surface of the transparent substrate 20 was 76°, and the phase shift film pattern 30a had a cross section shape that was nearly vertical. In addition, when the phase shift film pattern 30a was observed from above and the LER of the phase shift film pattern 30a was observed, the edge of the phase shift film pattern (hole pattern) 30a was smooth and approximately linear, and was good. That is, no noticeable uneven shape was confirmed at the edge of the phase shift film pattern 30a viewed from above. The phase shift film pattern 30a formed in the phase shift mask of Example 1 had a cross section shape that could fully exert the phase shift effect. In addition, the surface of the exposed transparent substrate 20 after removing the phase shift film 30 was smooth, and the decrease in transmittance due to the surface roughness of the transparent substrate 20 was negligible. In addition, when the obtained phase shift mask 100 was observed by electron beam diffraction, it was confirmed that it had an amorphous structure. Furthermore, no penetration of an etching solution or the like was observed at either the interface of phase shift film pattern 30a with etching mask film pattern 40b or the interface with transparent substrate 20, and chemical resistance was also good. Therefore, phase shift mask 100 having an excellent phase shift effect was obtained with exposure light including light in the wavelength range of 313 nm to 500 nm, more specifically, exposure light of a composite light including at least one of i-line, h-line, and g-line.
Therefore, when the phase shift mask 100 of Example 1 is set on the mask stage of an exposure device and exposed and transferred to a resist film on a display device substrate, it can be said that a fine pattern of less than 2.0 μm can be transferred with high precision. In addition, the phase shift film 30 (phase shift film pattern 30 a) is a dense film formed under a low vacuum of 0.5 Pa or less, and is therefore expected to have good light resistance to exposure light.

Examples 2 to 4.
A. Phase Shift Mask Blank In Examples 2 to 4, phase shift mask blank 10 and phase shift mask 100 were manufactured with the same structure and method as in Example 1, except for phase shift film 30. In Examples 2 to 4, the atomic ratios of Mo, Zr, and Si in the sputtering target used in forming phase shift film 30 in Example 1 were appropriately adjusted. The thickness of phase shift film 30 was appropriately adjusted so that the transmittance at a wavelength of 405 nm was 20% or more and 80% or less, and the phase difference was in the range of 160° to 200°.
As in Example 1, the composition of the MoZrSiN-based phase shift film 30 thus obtained was analyzed, and the atomic ratio of Mo to Zr was found to be as follows:
Example 2 Mo:Zr=1.5:1 (1:0.67),
Example 3 Mo:Zr=1:2,
Example 4 Mo:Zr=1:4,

Thus, in all of Examples 2 to 4, Mo:Zr was in the range of 1:0.67 to 1:4. In addition, the silicon content ratio to the total of molybdenum, zirconium, and silicon was in the range of [Si/(Mo+Zr+Si)] = 70 to 88 atomic % in all of Examples 2 to 4.

B. Phase shift mask and its manufacturing method In the same manner as in Example 1 described above, a phase shift mask 100 was produced, and the cross-sectional shape of the phase shift film pattern 30a and the surface state of the exposed transparent substrate 20 after removing the phase shift film 30 were confirmed. As a result, in all of Examples 2 to 4, the angle between the edge of the phase shift film pattern 30a of the phase shift mask 100 and the main surface of the transparent substrate 20 when viewed in cross section exceeded 70°, and all of the phase shift film patterns 30a had a cross-sectional shape that was close to vertical. In addition, when the LER of these phase shift film patterns 30a was observed in the same manner as in Example 1, the edges of the phase shift film pattern (hole pattern) 30a in all of Examples 2 to 4 were smooth and approximately linear, and were good. That is, no noticeable uneven shape was confirmed at the edge of the phase shift film pattern 30a viewed from above. The phase shift film pattern 30a formed in the phase shift masks of Examples 2 to 4 had a cross-sectional shape that could fully exert the phase shift effect. In addition, in all of Examples 2 to 4, the surface of the exposed transparent substrate 20 after removing the phase shift film 30 was smooth, and the decrease in transmittance due to the surface roughness of the transparent substrate 20 was negligible. In addition, when the obtained phase shift mask 100 was observed by electron beam diffraction, it was confirmed that the phase shift mask 100 had an amorphous structure in all of Examples 2 to 4. In addition, in all of Examples 2 to 4, no penetration of an etching solution or the like was observed at the interface between the phase shift film pattern 30a and the etching mask film pattern 40b and the interface between the phase shift film pattern 30a and the transparent substrate 20, and the chemical resistance was also good. Therefore, in all of Examples 2 to 4, a phase shift mask 100 having an excellent phase shift effect was obtained with exposure light including light in the wavelength range of 313 nm to 500 nm, more specifically, exposure light including at least one of i-line, h-line, and g-line.
Therefore, when the phase shift mask 100 of Examples 2 to 4 is set on the mask stage of an exposure device and exposed and transferred to a resist film on a display device substrate, it can be said that a fine pattern of less than 2.0 μm can be transferred with high precision. In addition, the phase shift film 30 (phase shift film pattern 30 a) is formed in a low vacuum state of 0.5 Pa or less to form a dense film, and is therefore expected to have good light resistance to exposure light.

Example 5.
A. Phase shift mask blank The phase shift mask blank 10 of Example 5 is a phase shift mask blank 10 in which the back reflectance of the phase shift film 30 in the exposure light is reduced. In the above-mentioned formation of the phase shift film 30 in Example 1, a mixed gas consisting of argon (Ar) gas and nitrogen (N ₂ ) gas was first introduced into the first chamber in a state in which the sputtering gas pressure was set to 0.5 Pa. Then, a MoZrSi target having an atomic ratio of Mo, Zr, and Si of Mo:Zr:Si=10:10:80 was used to form a MoZrSiN-based underlayer film containing molybdenum, zirconium, silicon, and nitrogen to a thickness of 105 nm on the main surface of the transparent substrate 20 by reactive sputtering. Note that the atomic ratio in the above target for sputtering is an example, and can be appropriately selected according to the desired composition of the phase shift film 30.
Thereafter, a mixed gas consisting of argon (Ar) gas, nitrogen ( _N2 ) gas, and nitric oxide (NO) gas was introduced into the second chamber with the sputtering gas pressure set to 1.6 Pa. Then, using a MoSi target with an atomic ratio of Mo and Si of Mo:Si=8:92, a MoSiON-based upper layer film containing molybdenum, silicon, oxygen, and nitrogen was formed to a thickness of 44 nm on the MoZrSiN-based lower layer film by reactive sputtering, thereby forming a phase shift film 30 consisting of a laminated film having a MoZrSiN-based lower layer film and a MoSiON-based upper layer film.
Next, in the same manner as in Example 1, an etching mask film 40 having a laminated structure of a CrN layer, a CrC layer, and a CrCON layer was formed on the phase shift film 30, and a phase shift mask blank 10 in which the phase shift film 30 and the etching mask film 40 were formed on the transparent substrate 20 was obtained.

The refractive index and extinction coefficient of the lower and upper layers constituting phase shift film 30 of the obtained phase shift mask blank 10 were measured using a dummy substrate prepared and set on the same tray.
As a result, the refractive index n of the MoZrSiN-based lower layer was 2.45 (wavelength: 405 nm), the extinction coefficient k was 0.11 (wavelength: 405 nm), and the refractive index n of the MoSiN-based upper layer was 2.24 (wavelength: 405 nm), the extinction coefficient k was 0.14 (wavelength: 405 nm).
Furthermore, the transmittance and phase difference of the phase shift film 30 of the obtained phase shift mask blank 10 were measured in the same manner as in Example 1. As a result, the transmittance was 51% (wavelength: 405 nm), the phase difference was 180° (wavelength: 405 nm), the back surface reflectance was 9.8% (wavelength: 405 nm), and the front surface reflectance was 14.9% (wavelength: 405 nm).

As in Example 1, the phase shift film 30 of the obtained phase shift mask blank 10 was subjected to composition analysis in the depth direction by X-ray photoelectron spectroscopy (XPS).
In the results of the composition analysis of the phase shift mask blank 10 in the depth direction by XPS, the contents of the constituent elements of the phase shift film 30 are almost constant in the depth direction except for the composition gradient region at the interface between the transparent substrate 20 and the phase shift film 30 and the composition gradient region at the interface between the phase shift film 30 and the etching mask film 40, and the lower layer film contains 3 atomic % Mo, 5 atomic % Zr, 42 atomic % Si, 47 atomic % N, and 3 atomic % O. The atomic ratio of molybdenum to zirconium was Mo:Zr=1:1, and was within the range of Mo:Zr=1:0.67 to 1:4. The content ratio of silicon to the total of molybdenum, zirconium, and silicon was 84 atomic %, and was within the range of [Si/(Mo+Zr+Si)]=70 to 88 atomic %. The upper layer film had 6 atomic % Mo, 41 atomic % Si, 47 atomic % N, and 6 atomic % O. Incidentally, it is believed that the oxygen contained in the lower layer film is due to the presence of a trace amount of oxygen in the chamber during film formation.

B. Phase shift mask and its manufacturing method In the same manner as in the above-mentioned embodiment, a phase shift mask 100 was produced, and the cross-sectional shape of the phase shift film pattern 30a and the surface state of the exposed transparent substrate 20 after removing the phase shift film 30 were confirmed. In cross-sectional view, the angle between the edge of the phase shift film pattern 30a of the phase shift mask 100 and the main surface of the transparent substrate 20 was 72°, exceeding 70°, and the phase shift film pattern 30a had a cross-sectional shape that was nearly vertical. In addition, as in the first embodiment, when the LER of this phase shift film pattern 30a was observed, the edge of the phase shift film pattern (hole pattern) 30a was smooth and approximately linear, and was good. That is, no noticeable uneven shape was confirmed at the edge of the phase shift film pattern 30a viewed from above. The phase shift film pattern 30a formed in the phase shift mask 100 of the fifth embodiment had a cross-sectional shape that could fully exert the phase shift effect. In addition, the surface of the exposed transparent substrate 20 after removing the phase shift film 30 was smooth, and the decrease in transmittance due to the surface roughness of the transparent substrate 20 was negligible. In addition, when the obtained phase shift mask 100 was observed by electron beam diffraction, it was confirmed that it had an amorphous structure. In addition, no penetration of etching solution or the like was observed at either the interface between the phase shift film pattern 30a and the etching mask film pattern 40b or the interface between the phase shift film pattern 30a and the transparent substrate 20, and the chemical resistance was also good. Therefore, a phase shift mask 100 having an excellent phase shift effect was obtained in the exposure light including light in the wavelength range of 313 nm to 500 nm, more specifically, in the exposure light of a composite light including at least one of i-line, h-line, and g-line.
Therefore, when the phase shift mask 100 of Example 5 is set on the mask stage of an exposure device and exposed and transferred to a resist film on a display device substrate, it can be said that a fine pattern of less than 2.0 μm can be transferred with high precision. In addition, the phase shift film 30 (phase shift film pattern 30 a) is a dense film formed under a low vacuum of 0.5 Pa or less, and is therefore expected to have good light resistance to exposure light.

Comparative Example 1.
A. Phase Shift Mask Blank In Comparative Example 1, a phase shift mask blank 10 and a phase shift mask 100 were manufactured with the same structure and method as in Example 1, except for phase shift film 30. In Comparative Example 1, the atomic ratios of Mo, Zr, and Si in the sputtering target used in forming phase shift film 30 in Example 1 were appropriately adjusted. The thickness of the phase shift film was appropriately adjusted so that the transmittance at a wavelength of 405 nm was 20% or more and 80% or less, and the phase difference was in the range of 160° to 200°.
As in Example 1, the composition of the MoZrSiN-based phase shift film 30 thus obtained was analyzed, and the atomic ratio of Mo to Zr was found to be as follows:
Comparative Example 1
Mo:Zr=1:1, [Si/(Mo+Zr+Si)]=90 atomic %
Thus, in Comparative Example 1, Mo:Zr was within the range of 1:0.67 to 1:4, but was outside the range of [Si/(Mo+Zr+Si)]=70 to 88 atomic %.

B. Phase Shift Mask and Manufacturing Method Thereof Phase shift mask 100 was fabricated in the same manner as in Example 1 described above, and the cross-sectional shape of phase shift film pattern 30a and the surface state of exposed transparent substrate 20 after phase shift film 30 was removed were confirmed.
As a result, in Comparative Example 1, the cross-sectional shape of the phase shift film pattern 30a was good and not significantly different from that of the other Examples, but the surface of the transparent substrate 20 exposed after removing the phase shift film 30 was rough and appeared cloudy even when observed visually. Therefore, the decrease in transmittance due to the surface roughness of the transparent substrate 20 was significant.
For this reason, when phase shift mask 100 of Comparative Example 1 is set on the mask stage of an exposure tool and exposed and transferred to a resist film on a substrate for a display device, it is expected that a fine pattern of less than 2.0 μm cannot be transferred.

Comparative Example 2.
A. Phase Shift Mask Blank In Comparative Example 2, a phase shift mask blank 10 and a phase shift mask 100 were manufactured with the same structure and method as in Example 1, except for phase shift film 30. In Comparative Example 2, the atomic ratios of Mo, Zr, and Si in the sputtering target used in forming phase shift film 30 in Example 1 were appropriately adjusted. The thickness of phase shift film 30 was appropriately adjusted so that the transmittance at a wavelength of 405 nm was 20% or more and 80% or less, and the phase difference was in the range of 160° to 200°.
As in Example 1, the composition of the MoZrSiN-based phase shift film 30 thus obtained was analyzed, and the atomic ratio of Mo to Zr was found to be as follows:
Comparative Example 2
Mo:Zr=1:1, [Si/(Mo+Zr+Si)]=65 atomic %
Thus, in Comparative Example 2, Mo:Zr was within the range of 1:0.67 to 1:4, but was outside the range of [Si/(Mo+Zr+Si)]=70 to 88 atomic %.

B. Phase Shift Mask and Manufacturing Method Thereof Phase shift mask 100 was fabricated in the same manner as in Example 1 described above, and the cross-sectional shape of phase shift film pattern 30a and the surface state of exposed transparent substrate 20 after phase shift film 30 was removed were confirmed.
As a result, in Comparative Example 2, the surface of the exposed transparent substrate 20 after removing the phase shift film 30 was smooth, and the decrease in transmittance due to the roughness of the surface of the transparent substrate 20 was negligible, but the cross-sectional shape of the phase shift film pattern 30a was poor and did not have a cross-sectional shape that could fully exert the phase shift effect.
For this reason, when phase shift mask 100 of Comparative Example 2 is set on the mask stage of an exposure tool and exposed and transferred to a resist film on a substrate for a display device, it is expected that a fine pattern of less than 2.0 μm cannot be transferred.

Comparative Example 3.
A. Phase Shift Mask Blank In Comparative Example 3, phase shift mask blank 10 and phase shift mask 100 were manufactured with the same structure and method as in Example 1, except for phase shift film 30. In Comparative Example 3, the atomic ratios of Mo, Zr, and Si in the sputtering target used in forming phase shift film 30 in the above-mentioned Example 1 were appropriately adjusted.
As in Example 1, a composition analysis was performed on the obtained MoZrSiN-based phase shift film 30, and the atomic ratio in Comparative Example 3 was Mo:Zr=2:1, which was outside the range of 1:0.67 to 1:4. On the other hand, the content ratio of silicon to the total of molybdenum, zirconium, and silicon was within the range of [Si/(Mo+Zr+Si)]=70 to 88 atomic %.

B. Phase Shift Mask and Manufacturing Method Thereof Phase shift mask 100 was fabricated in the same manner as in Example 1 described above, and the cross-sectional shape of phase shift film pattern 30a and the surface state of exposed transparent substrate 20 after phase shift film 30 was removed were confirmed.
As a result, in Comparative Example 3, the surface of the exposed transparent substrate 20 after removing the phase shift film 30 was smooth, and the decrease in transmittance due to the surface roughness of the transparent substrate 20 was negligible. In addition, the cross-sectional shape of the phase shift film pattern 30a was not significantly different from that of the other Examples and was good. On the other hand, the transmittance at a wavelength of 405 nm was below 15%, and sufficient transmittance was not obtained. Although the film thickness was adjusted in the same manner as in the other Examples and Comparative Examples, sufficient transmittance was still not obtained.
For this reason, when phase shift mask 100 of Comparative Example 3 is set on the mask stage of an exposure tool and exposed and transferred to a resist film on a substrate for a display device, it is expected that a fine pattern of less than 2.0 μm cannot be transferred.

Comparative Example 4.
A. Phase Shift Mask Blank In Comparative Example 4, a phase shift mask blank 10 and a phase shift mask 100 were manufactured with the same structure and method as in Example 1, except for phase shift film 30. In Comparative Example 4, the atomic ratios of Mo, Zr, and Si in the sputtering target used in forming the phase shift film in Example 1 were appropriately adjusted. The thickness of phase shift film 30 was appropriately adjusted so that the transmittance at a wavelength of 405 nm was 20% or more and 80% or less, and the phase difference was in the range of 160° to 200°.
As in Example 1, a composition analysis was performed on the obtained MoZrSiN-based phase shift film 30. As a result, in Comparative Example 4, the atomic ratio of molybdenum to zirconium was Mo:Zr=1:5, which was outside the range of 1:0.67 to 1:4. On the other hand, the content ratio of silicon to the total of molybdenum, zirconium, and silicon was within the range of [Si/(Mo+Zr+Si)]=70 to 88 atomic %.

B. Phase Shift Mask and Manufacturing Method Thereof Phase shift mask 100 was fabricated in the same manner as in Example 1 described above, and the cross-sectional shape of the phase shift film pattern and the surface state of transparent substrate 20 exposed after removing phase shift film 30 were confirmed.
As a result, in Comparative Example 4, the surface of the transparent substrate 20 exposed after removing the phase shift film 30 was smooth, and the decrease in transmittance due to the surface roughness of the transparent substrate 20 was negligible, but sufficient chemical resistance was not obtained, and the cross-sectional shape of the phase shift film pattern 30a was deteriorated compared to the other Examples. In addition, both the front surface reflectance and the back surface reflectance at a wavelength of 405 nm were high, and sufficient transfer accuracy was not obtained.
For this reason, when phase shift mask 100 of Comparative Example 4 is set on the mask stage of an exposure tool and exposed and transferred to a resist film on a substrate for a display device, it is expected that a fine pattern of less than 2.0 μm cannot be transferred.

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

Claims (9)

A photomask blank having a phase shift film on a transparent substrate,
the photomask blank is a master for forming a photomask, the photomask having a phase shift film pattern obtained by wet etching the phase shift film on the transparent substrate,
the phase shift film is composed of a single layer or multiple layers, and 50% to 100% of the total thickness of the phase shift film is a MoZrSi-based material layer made of a material containing molybdenum (Mo), zirconium (Zr), silicon (Si) and nitrogen;
The MoZrSi-based material layer has an atomic ratio of molybdenum and zirconium of Mo:Zr=1.5:1 to 1:4, and a silicon content ratio of the total of molybdenum, zirconium and silicon is 70 to 88 atomic %. The photomask blank of claim 1, characterized in that the phase shift film has optical properties of a transmittance of 20% or more and 80% or less for the representative wavelength of the exposure light, and a phase difference of 160° or more and 200° or less. The photomask blank according to claim 1 or 2, characterized in that the phase shift film is a laminated film including a lower layer on the transparent substrate side and an upper layer laminated on the lower layer, and the lower layer is the MoZrSi-based material layer. The photomask blank of claim 3, characterized in that the upper layer is made of a material that has a refractive index smaller than that of the lower layer and a higher extinction coefficient at the representative wavelength of the exposure light. The photomask blank according to claim 4, characterized in that the refractive index, extinction coefficient, and film thickness of the upper layer and the lower layer of the phase shift film are set so that the back reflectance for the representative wavelength of the exposure light is 15% or less. The photomask blank according to any one of claims 1 to 5, characterized in that an etching mask film having a different etching selectivity with respect to the phase shift film is provided on the phase shift film. A step of preparing a photomask blank according to any one of claims 1 to 5;
forming a resist film on the phase shift film, and wet-etching the phase shift film using a resist film pattern formed from the resist film as a mask to form a phase shift film pattern on the transparent substrate. Providing a photomask blank according to claim 6;
forming a resist film on the etching mask film, and wet-etching the etching mask film using a resist film pattern formed from the resist film as a mask to form an etching mask film pattern on the phase shift film;
and wet-etching the phase shift film using the etching mask film pattern as a mask to form a phase shift film pattern on the transparent substrate. A method for manufacturing a display device, comprising an exposure step of placing a photomask obtained by the photomask manufacturing method according to claim 7 or 8 on a mask stage of an exposure device, and exposing and transferring a transfer pattern including the phase shift film pattern formed on the photomask to a resist formed on a display device substrate.

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