Photomask blank, method for manufacturing photomask, and method for manufacturing display device

Abstract

The present invention aims to provide a photomask blank that can shorten overetching time, suppress substrate damage, and form a transferred pattern having a good cross-sectional shape, LER, and excellent chemical resistance when wet-etching a phase shift film. The photomask blank is a master plate for forming a photomask having a phase shift film pattern formed by wet-etching a phase shift film on a transparent substrate. The phase shift film is composed of a single layer or multiple layers and comprises a MoZrSi-based material layer composed of a material containing molybdenum, zirconium, silicon, and nitrogen, accounting for at least 50% and no more than 100% of the total film thickness. The atomic ratio of molybdenum to zirconium in the MoZrSi-based material layer is Mo:Zr = 1.5:1 to 1:4, and the silicon content is 70 to 88 atomic percent relative to the total of molybdenum, zirconium, and silicon.

Description

Technical Field

[0001] The present invention relates to a photomask blank, a method for manufacturing a photomask, and a method for manufacturing a display device. Background Art

[0002] In recent years, display devices such as FPDs (Flat Panel Displays) represented by LCDs (Liquid Crystal Displays) have been rapidly developing not only to have larger screens and wider viewing angles, but also to have higher resolution and higher speed displays. One of the elements required for this high resolution and high speed display is the production of electronic circuit patterns such as components and wiring that are fine and have high dimensional accuracy. The patterning of electronic circuits for these display devices is mostly done using photolithography. Therefore, photomasks such as phase-shift masks and binary masks are needed for the manufacture of display devices that have fine and high-precision patterns.

[0003] For example, Patent Document 1 discloses a phase reversal mask blank having a phase reversal film on a transparent substrate. In this mask blank, the phase reversal film is composed of a multilayer film of two or more layers formed of a metal silicide compound containing at least one light element of oxygen (O), nitrogen (N), and carbon (C). The film has a reflectivity of 35% or less and a transmittance of 1% to 40% for exposure light having a composite wavelength including i-line (365nm), h-line (405nm), and g-line (436nm), and forms a sharp gradient in the pattern cross section during patterning. The metal silicide compound is formed by injecting a reactive gas containing the light element to an inert gas at a ratio of 0.5:9.5 to 4:6.

[0004] As the above-mentioned metal silicide compounds, the following materials are described, which are formed by containing silicon (Si) 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 are formed by further containing one or more light element substances selected from nitrogen (N), oxygen (O), carbon (C), boron (B), and hydrogen (H) in the above-mentioned metal silicide.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Korean Patent No. 1801101

[0008] Patent Document 2: Japanese Patent No. 3988041 Summary of the Invention

[0009] Problems to be solved by the invention

[0010] Phase shift masks used in recent years in the production of high-definition panels (1000 ppi or higher) require a fine phase shift film pattern with an aperture of 6 μm or less and a line width of 4 μm or less to transfer high-resolution patterns. Specifically, a phase shift mask with a fine phase shift film pattern with an aperture of 1.5 μm is required.

[0011] Furthermore, in order to achieve higher-resolution pattern transfer, a phase shift mask blank having a phase shift film having a transmittance of 15% or more to exposure light and a phase shift mask having a phase shift film pattern having a transmittance of 15% or more to exposure light are required.

[0012] In order to meet the requirements for the transmittance of 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-based material) that constitutes the phase shift film. However, there are problems such as a significant delay in the wet etching rate (long wet etching time), damage to the substrate by the wet etching solution, and a decrease in the transmittance of the transparent substrate.

[0013] Patent Document 2 discloses a halftone phase shift mask blank having a phase shift film on a transparent substrate. The phase shift film is formed from 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. The patent discloses that, from the perspective of chemical resistance and processability during etching of the phase shift film, 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).

[0014] The phase shift film disclosed in Patent Document 2 is assumed to be patterned by dry etching when forming a phase shift mask. However, if the phase shift film is patterned by wet etching, similarly to the above, there are problems such as a slow wet etching rate for the phase shift film, damage to the substrate by the wet etching solution, and reduced transmittance of the transparent substrate.

[0015] Therefore, the present invention has been completed to solve the above-mentioned problems. The purpose of the present invention is to provide a photomask blank, a method for manufacturing a photomask, and a method for manufacturing a display device. Even when the transmittance of the phase shift film with respect to the representative wavelength of exposure light is high, the photomask blank can shorten the wet etching time of the phase shift film containing metal and silicon when forming the transfer pattern of the photomask, thereby suppressing damage to the substrate, thereby forming a transfer pattern having a good cross-sectional shape, line edge roughness (LER), and good chemical resistance.

[0016] Solutions to the Problem

[0017] The inventors conducted intensive research to develop solutions to these problems. First, to create a phase shift film with high transmittance for typical wavelengths of exposure light (e.g., 313 nm to 436 nm), they focused on zirconium, which has an extinction coefficient lower than that of molybdenum at these wavelengths. As the material for the phase shift film, they selected a MoZrSi-based material containing molybdenum, zirconium, silicon, and nitrogen.

[0018] It is known that MoZrSi-based materials are used as phase shift films in LSI mask blanks used in semiconductor device manufacturing, among other applications. However, it is known that wet etching of the phase shift film is excessively time-consuming when attempting to directly use the MoZrSi-based materials used in LSI mask blanks for phase shift mask blanks used in display device manufacturing, and that damage to the substrate and a decrease in the transmittance of the transparent substrate cannot be adequately suppressed. Consequently, even if MoZrSi-based materials used in LSI mask blanks are simply used in phase shift mask blanks used in display device manufacturing, the desired phase shift mask blank for display device manufacturing cannot be obtained.

[0019] It is also known that depending on the composition ratio of the MoZrSi-based material, the chemical resistance of the phase shift film is poor, the desired cleaning resistance cannot be obtained, and the reflectivity is too high, which degrades the transfer characteristics.

[0020] Therefore, the present inventors conducted further in-depth research and discovered that it is effective to regulate the atomic ratio of molybdenum to zirconium and the content ratio of silicon relative to the total of molybdenum, zirconium, and silicon in MoZrSi-based materials as indicators. Specifically, the present inventors discovered that, when patterning the phase shift film using wet etching, the wet etching rate of the phase shift film is high. To prevent damage to the transparent substrate caused by the wet etching solution during patterning of the phase shift film, the aforementioned problem can be solved by adjusting the atomic ratio of molybdenum to zirconium and the content ratio of silicon relative to the total of molybdenum, zirconium, and silicon in the MoZrSi-based material. The present invention, resulting from the above-mentioned in-depth research, has the following configuration.

[0021] (Scheme 1) A photomask blank having a phase shift film on a transparent substrate,

[0022] The photomask blank is a master plate for forming a photomask having a phase shift film pattern on the transparent substrate. The phase shift film pattern is obtained by wet etching the phase shift film.

[0023] The phase shift film is composed of a single layer or multiple layers, and includes a MoZrSi-based material layer composed of a material containing molybdenum (Mo), zirconium (Zr), silicon (Si), and nitrogen, which accounts for not less than 50% and not more than 100% of the total film thickness of the phase shift film.

[0024] The atomic ratio of molybdenum to zirconium in the MoZrSi-based material layer is Mo:Zr=1.5:1 to 1:4 (1:0.67 to 1:4), and the content of silicon relative to the total of molybdenum, zirconium, and silicon is 70 to 88 atomic %.

[0025] (Scheme 2) The photomask blank according to scheme 1, wherein

[0026] The phase shift film has the following optical characteristics: a transmittance of 20% to 80% inclusive with respect to a representative wavelength of exposure light, and a phase difference of 160° to 200° inclusive.

[0027] (Scheme 3) The photomask blank according to scheme 1 or 2, wherein

[0028] 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.

[0029] (Scheme 4) The photomask blank according to scheme 3, wherein

[0030] The upper layer is formed of a material having a lower refractive index at a representative wavelength of exposure light than that of the lower layer and a higher extinction coefficient than that of the lower layer.

[0031] (Scheme 5) The photomask blank according to scheme 4, wherein

[0032] The refractive index, extinction coefficient, and film thickness of each of the upper layer and the lower layer are set so that the back surface reflectance of the phase shift film with respect to a representative wavelength of exposure light is 15% or less.

[0033] (Structure 6) The photomask blank according to any one of Structures 1 to 5, wherein

[0034] An etching mask film having a different etching selectivity with respect to the phase shift film is provided on the phase shift film.

[0035] (Scheme 7) A method for manufacturing a photomask, the method comprising:

[0036] a step of preparing the photomask blank according to any one of items 1 to 5; and

[0037] A step of forming a resist film on the phase shift film, and wet-etching the phase shift film using a resist pattern formed by the resist film as a mask to form a phase shift film pattern on the transparent substrate.

[0038] (Scheme 8) A method for manufacturing a photomask, the method comprising:

[0039] a step of preparing the photomask blank described in claim 6;

[0040] forming a resist film on the etching mask film, and wet-etching the etching mask film using the resist film pattern formed by the resist film as a mask to form an etching mask film pattern on the phase shift film; and

[0041] A step of 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.

[0042] (Scheme 9) A method for manufacturing a display device, the method comprising

[0043] An exposure step in which the photomask obtained by the photomask manufacturing method described in claim 7 or 8 is placed on a mask stage of an exposure device, and a transfer pattern including the phase shift film pattern formed on the photomask is transferred by exposure to a resist formed on a display device substrate.

[0044] Effects of the Invention

[0045] According to the photomask blank of the present invention, even when the transmittance of the phase shift film with respect to the representative wavelength of exposure light is high, the wet etching time of the phase shift film containing metal and silicon can be shortened when forming the transfer pattern of the photomask, thereby forming a photomask blank having a good cross-sectional shape, line edge roughness, and chemical resistance.

[0046] Furthermore, according to the photomask manufacturing method of the present invention, a photomask is manufactured using the aforementioned photomask blank. Therefore, even when the transmittance of the phase shift film at the representative wavelength of exposure light is high, the wet etching rate of the phase shift film is high, and damage to the transparent substrate by the wet etching solution, which would otherwise cause a decrease in the transmittance of the transparent substrate, can be avoided. This allows the manufacture of a photomask having a transferred pattern (phase shift film pattern) with excellent transfer accuracy, line edge roughness, and chemical resistance. This photomask is capable of addressing the miniaturization of line and space patterns and contact holes.

[0047] Furthermore, according to the method for manufacturing a display device of the present invention, a display device is manufactured using a photomask obtained by the above-mentioned method for manufacturing a photomask, thereby enabling the manufacture of a display device having a fine line and space pattern and contact holes.

[0048] Furthermore, according to the method for manufacturing a display device of the present invention, a display device is manufactured using a photomask obtained by the above-mentioned method for manufacturing a photomask. Therefore, a display device having a fine line and space pattern and contact holes can be manufactured. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 This is an explanatory diagram showing the film structure (transparent substrate / phase shift film) of the phase shift mask blank according to the first embodiment.

[0050] Figure 2 This is an explanatory diagram showing the film structure (transparent substrate / phase shift film / etching mask film) of a phase shift mask blank according to the second embodiment.

[0051] Figure 3 It is an explanatory diagram showing the manufacturing process of the phase shift mask of Embodiment 3.

[0052] Figure 4 It is an explanatory diagram showing the manufacturing process of the phase shift mask of the fourth embodiment.

[0053] Explanation of symbols

[0054] 10…Phase shift mask blanks

[0055] 20…Transparent substrate

[0056] 30…Phase shift film

[0057] 30a…Phase shift film pattern

[0058] 40…Etching mask film

[0059] 40a...first etching mask film pattern

[0060] 40b...second etching mask film pattern

[0061] 50…first resist pattern

[0062] 60…Second resist pattern

[0063] 100…Phase shift mask DETAILED DESCRIPTION

[0064] Implementation methods 1 and 2

[0065] In Embodiments 1 and 2, a phase-shift mask blank (photomask blank) is described. The phase-shift mask blank of Embodiment 1 is a master for forming a phase-shift mask (photomask). This phase-shift mask is a phase-shift mask having a transfer pattern including the phase-shift film pattern formed on a transparent substrate, obtained by wet-etching the phase-shift film, using an etching mask film pattern having a desired pattern formed on an etching mask film as a mask. Furthermore, the phase-shift mask blank of Embodiment 2 is a master for forming a phase-shift mask. This phase-shift mask is a phase-shift mask having a transfer pattern including the phase-shift film pattern formed on a transparent substrate, obtained by wet-etching the phase-shift film, using a resist film pattern having a desired pattern formed on a 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 described above can serve as a phase shift film or an etching mask film, and may further include other films (light-shielding films, films for suppressing reflection, conductive films, etc.). In other words, the transferred pattern may include a patterned phase shift film or etching mask film, and may further include other patterned films.

[0066] Figure 1 It is an explanatory diagram showing the film structure of the phase shift mask blank 10 according to the first embodiment.

[0067] Figure 1 The illustrated phase shift mask blank 10 includes a transparent substrate 20 , a phase shift film 30 formed on the transparent substrate 20 , and an etching mask film 40 formed on the phase shift film 30 .

[0068] Figure 2 It is an explanatory diagram showing the film structure of the phase shift mask blank 10 according to the second embodiment.

[0069] Figure 2 The phase shift mask blank 10 shown includes a transparent substrate 20 and a phase shift film 30 formed on the transparent substrate 20 .

[0070] Hereinafter, the transparent substrate 20 , the phase shift film 30 , and the etching mask film 40 constituting the phase shift mask blank 10 according to the first and second embodiments will be described.

[0071] The transparent substrate 20 is transparent to the exposure light. In the absence of surface reflection loss, the transparent substrate 20 has a transmittance of 85% or more, preferably 90% or more, to the exposure light. The transparent substrate 20 is made of a material containing silicon and oxygen, and can be composed of glass materials such as synthetic quartz glass, quartz glass, aluminosilicate glass, soda-lime glass, and low thermal expansion glass (SiO2-TiO2 glass, etc.). When the transparent substrate 20 is composed of low thermal expansion glass, the position change of the phase shift film pattern caused by thermal deformation of the transparent substrate 20 can be suppressed. In addition, the transparent substrate 20 used in display devices is generally a rectangular substrate, and a substrate with a short side length of 300 mm or more can be used. The phase shift mask blank 10 of the present invention can provide a phase shift mask 100 that can stably transfer a fine phase shift film pattern (for example, a width or diameter of less than 2.0 μm) formed on the transparent substrate 20 even if the short side length of the transparent substrate 20 is large, such as 300 mm or more.

[0072] The phase shift film 30 is composed of a single layer or multiple layers, with a portion comprising at least 50% and no more than 100% of the overall thickness of the phase shift film 30 being composed 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).

[0073] Furthermore, as long as the transmittance and phase difference of the phase shift film 30 for the representative wavelength of exposure light are predetermined values, the portion of the phase shift film 30 that is less than 50% of the total film thickness of the phase shift film 30 may be formed of a material other than a MoZrSi-based material. In this case, a metal silicide-based material containing metal and silicon that can be etched using a wet etchant similar to the MoZrSi-based material is preferred. For example, examples of metal silicide-based materials other than MoZrSi 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 also contain elements such as nitrogen, oxygen, and carbon.

[0074] In the MoZrSi-based material layer, the atomic ratio of molybdenum to zirconium is Mo:Zr = 1.5:1 to 1:4, or Mo:Zr = 1:0.67 to 1:4. In the case of a MoZrSi-based material layer with a Zr ratio below the above-mentioned Mo:Zr atomic ratio range, the wet etching rate with a wet etching solution is slow, and thus damage to the transparent substrate is likely to occur. Furthermore, it becomes difficult to obtain a phase shift film with high transmittance for the representative wavelength of exposure light. In the case of a MoZrSi-based material layer with a Zr ratio above the above-mentioned Mo:Zr atomic ratio range, a phase shift film 30 with high transmittance (e.g., 20% to 80%) for the representative wavelength of exposure light is likely to be obtained, but chemical resistance (cleaning resistance) is insufficient, which is not preferred from the perspective of defect quality caused by 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.

[0075] Furthermore, the ratio of silicon to the total of molybdenum, zirconium, and silicon in the MoZrSi-based material layer (Si / [Mo+Zr+Si]) is preferably set to Si / [Mo+Zr+Si] = 70 to 88 atomic%. If Si / [Mo+Zr+Si] is less than 70 atomic%, it is difficult to achieve a phase shift film 30 with high transmittance (e.g., 20% to 80%) at a representative wavelength of exposure light and chemical resistance. Furthermore, if Si / [Mo+Zr+Si] exceeds 88 atomic%, the wet etching rate with the wet etching solution slows, which can easily damage the transparent substrate 20 and reduce the transmittance due to roughening of the transparent substrate 20. The 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%.

[0076] The phase shift film 30 can be formed by sputtering.

[0077] For the MoZrSi-based material layer of the phase shift film 30 in this embodiment, since the atomic ratio of molybdenum to zirconium and the content ratio of silicon relative to the total of molybdenum, zirconium and silicon satisfy the above-mentioned ranges, the film can be formed at a good vacuum degree within 0.5 Pa, the over-etching time can be shortened and damage to the transparent substrate 20 can be suppressed, and a phase shift film pattern 30a with a good cross-sectional shape, LER, and good chemical resistance can be formed.

[0078] It should be noted that the phase shift film 30 may have a columnar structure. This columnar structure can be confirmed by observing a cross section of the phase shift film 30 using a SEM. Specifically, 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 extending along the film thickness direction of the phase shift film 30 (the direction in which the particles are deposited). A phase shift film 30 having this columnar structure is preferred because it easily achieves high transmittance.

[0079] Furthermore, the phase shift film 30 may contain oxygen in addition to the above-mentioned nitrogen for the purpose of adjusting transmittance, and may contain other elements such as helium and carbon for the purpose of reducing film stress and controlling the wet etching rate.

[0080] The transmittance of the phase shift film 30 with respect to the exposure light satisfies the values ​​required for the phase shift film 30. With respect to light of a given wavelength (representative wavelength) contained in the exposure light, the transmittance of the phase shift film 30 is preferably 20% to 80%, more preferably 25% to 75%, and even more preferably 30% to 70%. Specifically, when the exposure light is composite light containing light in the wavelength range of 313 nm to 436 nm, the phase shift film 30 has the aforementioned transmittance with respect to light of the representative wavelength contained in this wavelength range. For example, when the exposure light is composite light containing i-line, h-line, and g-line, the phase shift film 30 has the aforementioned transmittance with respect to any one of the i-line, h-line, and g-line.

[0081] The transmittance can be measured using a phase shift measurement device or the like.

[0082] The phase difference of the phase shift film 30 relative to the exposure light satisfies the values ​​required for the phase shift film 30. The phase difference of the phase shift film 30 relative to light of a representative wavelength included in the exposure light is preferably 160° to 200°, more preferably 170° to 190°. This property allows the phase of light of a representative wavelength included in the exposure light to be changed (shifted) to 160° to 200°. Consequently, a phase difference of 160° to 200° is generated between light of a representative wavelength that has passed through the phase shift film 30 and light of a representative wavelength that has passed only through the transparent substrate 20. In other words, when the exposure light is composite light containing light in the wavelength range of 313 nm to 436 nm, the phase shift film 30 exhibits the aforementioned phase difference relative to light of a representative wavelength included in this wavelength range. For example, when the exposure light is composite light containing i-line, h-line, and g-line, the phase shift film 30 exhibits the aforementioned phase difference relative to any one of the i-line, h-line, and g-line.

[0083] The phase difference can be measured using a phase shift measuring device or the like.

[0084] Alternatively, the phase shift film 30 may be a laminated film comprising 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 comprising a lower layer and an upper layer, the lower layer is preferably a MoZrSi-based material layer from the perspectives of suppressing defects in the phase shift film 30, preventing damage to the transparent substrate 20 by a wet etching solution, and ensuring a good cross-sectional shape when patterning the phase shift film 30 by wet etching. The upper layer in the phase shift film 30 may be the same MoZrSi-based material as the lower layer, or may be different. When the upper layer and the lower layer are made of different materials, a metal silicide-based material that can be etched with the same wet etching solution as the MoZrSi-based material may be used, such as a MoSi-based material, a ZrSi-based material, a TaSi-based material, a WSi-based material, or a TiSi-based material.

[0085] In addition, the back reflectivity of the phase shift film 30 on the side where the exposure light is incident can be reduced by selecting a material such that the upper layer is formed of a material having a refractive index n that is smaller than the refractive index n of the lower layer at a representative wavelength of the exposure light (e.g., 313 nm to 436 nm) and an extinction coefficient k that is higher than the extinction coefficient k of the lower layer.

[0086] Specifically, the refractive index, extinction coefficient, and film thickness of the upper and lower layers can be set so that the back reflectivity for the representative wavelength of exposure light is 15% or less. Preferably, the back reflectivity of the phase shift film 30 for the representative wavelength of exposure light is 10% or less.

[0087] The etching mask film 40 is positioned above the phase shift film 30 and is formed from a material that is resistant to the etching solution used to etch the phase shift film 30 (different from the etching selectivity of the phase shift film 30). Furthermore, the etching mask film 40 can block the transmission of exposure light and reduce the film surface reflectivity, such that the film surface reflectivity of the phase shift film 30 is 15% or less within the wavelength range of 313 nm to 436 nm relative to light incident from the phase shift film 30 side. The etching mask film 40 is formed from a chromium-based material containing chromium (Cr). More specifically, examples of chromium-based materials include chromium (Cr) or materials containing chromium (Cr) and at least one of oxygen (O), nitrogen (N), and carbon (C). Alternatively, examples include materials containing chromium (Cr) and at least one of oxygen (O), nitrogen (N), and carbon (C), and also containing fluorine (F). For example, as a material constituting the etching mask film 40 , there can be mentioned Cr, CrO, CrN, CrF, CrCO, CrCN, CrON, CrCON, and CrCONF.

[0088] The etching mask film 40 can be formed by a sputtering method.

[0089] When the etching mask film 40 has the function of blocking exposure light, the optical density of the exposure light in the portion where the phase shift film 30 and the etching mask film 40 are stacked is preferably 3 or more, more preferably 3.5 or more, and even more preferably 4 or more.

[0090] Optical density can be measured using a spectrophotometer or an OD meter.

[0091] Depending on the function, the etching mask film 40 may be formed of a single film having a uniform composition, may be formed of a plurality of films having different compositions, or may be formed of a single film having a composition that continuously changes in the thickness direction.

[0092] It should be noted that Figure 1 The illustrated phase shift mask blank 10 includes the etching mask film 40 on the phase shift film 30 . However, the present invention can also be applied to a phase shift mask blank including the etching mask film 40 on the phase shift film 30 and a resist film on the etching mask film 40 .

[0093] Next, a method for manufacturing the phase shift mask blank 10 according to the first and second embodiments will be described. Figure 1 The phase shift mask blank 10 shown can be manufactured by performing the following phase shift film forming step and etching mask film forming step. Figure 2 The phase shift mask blank 10 shown can be manufactured through a phase shift film forming process.

[0094] Hereinafter, each step will be described in detail.

[0095] 1. Phase shift film formation process

[0096] First, prepare the transparent substrate 20. As long as the transparent substrate 20 is transparent to the exposure light, it can be made of any glass material such as synthetic quartz glass, quartz glass, aluminosilicate glass, soda-lime glass, or low thermal expansion glass (such as SiO2-TiO2 glass).

[0097] Next, the phase shift film 30 is formed on the transparent substrate 20 by sputtering.

[0098] The sputtering target used is a MoZrSi-based target containing molybdenum (Mo), zirconium (Zr), and silicon (Si) as 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), and oxygen (O) and / or nitrogen (N). The phase shift film 30 is formed in a sputtering gas atmosphere, for example, a sputtering gas atmosphere containing at least one inert gas selected from helium, neon, argon, krypton, and xenon, or a sputtering gas atmosphere formed by a mixture of such an inert gas and an active gas selected from oxygen, nitrogen, carbon dioxide, nitric oxide, and nitrogen dioxide, and containing at least nitrogen. The phase shift film 30 can be formed using a Mo target, a Zr target, or a Si target, so as to satisfy the aforementioned atomic ratio and content ratio of Mo, Zr, and Si. Alternatively, a MoSi target or a ZrSi target can be used to form the phase shift film 30.

[0099] The composition and thickness of the phase shift film 30 can be adjusted so that the phase shift film 30 has the aforementioned phase difference and transmittance. The composition of the phase shift film 30 can be controlled by, for example, 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, and the like. The thickness of the phase shift film 30 can be controlled by, for example, the sputtering power and sputtering time. Furthermore, the phase shift film 30 is preferably formed using an inline sputtering apparatus. In the case of an inline sputtering apparatus, the thickness of the phase shift film 30 can be controlled by the transport speed of the transparent substrate 20.

[0100] When the phase shift film 30 is formed from a single film, the above-described film formation process is performed only once, while the sputtering gas composition and flow rate are varied along with the film formation process duration. When the phase shift film 30 is formed from multiple films having different compositions, the above-described film formation process is performed multiple times, with the sputtering gas composition and flow rate varied according to the film formation process. The phase shift film 30 can be formed using sputtering targets having different element content ratios. When performing multiple film formation processes, the sputtering power applied to the sputtering target can be reduced.

[0101] In this manner, the phase-shift mask blank 10 of Embodiment 2 can be obtained. In the production of the phase-shift mask blank 10 of Embodiment 1, the following etching mask film forming step can be further performed.

[0102] 3. Etching mask film formation process

[0103] After surface treatment to adjust the surface oxidation state of the phase shift film 30, an etching mask film 40 is formed on the phase shift film 30 by sputtering. The etching mask film 40 is preferably formed using an inline sputtering apparatus. In the case of an inline sputtering apparatus, the thickness of the etching mask film 40 can be controlled by the transport speed of the transparent substrate 20.

[0104] The etching mask film 40 is formed using a sputtering target containing chromium or a chromium compound (chromium oxide, chromium nitride, chromium carbide, chromium oxynitride, chromium oxycarbonitride, etc.) in a sputtering gas atmosphere, for example, a sputtering gas atmosphere formed by at least one inert gas selected from helium, neon, argon, krypton, and xenon, or a sputtering gas atmosphere formed by a mixed gas of an inert gas and an active gas, wherein the inert gas includes at least one selected from helium, neon, argon, krypton, and xenon, and the active gas includes at least one selected from oxygen, nitrogen, nitric oxide, nitrogen dioxide, carbon dioxide, hydrocarbon gases, and fluorine-based gases. Examples of hydrocarbon gases include methane gas, butane gas, propane gas, and styrene gas.

[0105] When the etching mask film 40 is formed of a single film having a uniform composition, the above-described film formation process is performed only once without changing the composition and flow rate of the sputtering gas. When the etching mask film 40 is formed of multiple films having different compositions, the above-described film formation process is performed multiple times while changing the composition and flow rate of the sputtering gas according to the film formation process. When the etching mask film 40 is formed of a single film having a composition that continuously changes along the thickness direction, the composition and flow rate of the sputtering gas are changed along with the elapsed time of the film formation process, and the above-described film formation process is performed only once.

[0106] In this manner, the phase shift mask blank 10 according to the first embodiment can be obtained.

[0107] It should be noted that due to Figure 1 The phase shift mask blank 10 shown has an etching mask film 40 on the phase shift film 30. Therefore, when manufacturing the phase shift mask blank 10, an etching mask film forming step is performed. Alternatively, 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 step. Figure 2 In the illustrated phase shift mask blank 10 , when manufacturing a phase shift mask blank including a resist film on the phase shift film 30 , the resist film is formed after the phase shift film forming step.

[0108] The phase shift mask blank 10 of Embodiments 1 and 2 has a good cross-sectional shape when wet-etched, and can form a highly transmittance phase shift film pattern 30a in a short etching time. Consequently, a phase shift mask blank 10 is obtained that can be used to manufacture a phase shift mask 100 capable of accurately transferring a highly detailed phase shift film pattern 30a without damaging the transparent substrate 20 with a wet etching solution, thereby preventing a decrease in the transmittance of the transparent substrate 20.

[0109] Implementation methods 3 and 4

[0110] In the third and fourth embodiments, a method for manufacturing the phase shift mask 100 will be described.

[0111] Figure 3 It is an explanatory diagram showing a method for manufacturing the phase shift mask 100 according to the third embodiment. Figure 4 It is an explanatory diagram showing a method for manufacturing the phase shift mask 100 according to the fourth embodiment.

[0112] Figure 3 The phase shift mask 100 is manufactured using Figure 1 The method for manufacturing a phase shift mask 100 using a phase shift mask blank 10 shown in FIG. 1 includes: forming a resist film on an etching mask film 40 of the phase shift mask blank 10; drawing and developing a desired pattern on the resist film to form a resist film pattern 50 (a 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 40 a on the phase shift film 30 (a first etching mask film pattern forming step); and wet etching the phase shift film 30 using the etching mask film pattern 40 a as a mask to form a phase shift film pattern 30 a on the transparent substrate 20 (a phase shift film pattern forming step). Furthermore, the method includes a second resist film pattern forming step and a second etching mask film pattern forming step.

[0113] Figure 4 The phase shift mask 100 is manufactured using Figure 2 The method for manufacturing a phase shift mask 100 using the phase shift mask blank 10 shown in the figure includes: forming a resist film on the phase shift mask blank 10; drawing and developing a desired pattern on the resist film to form a resist film pattern 50 (a first resist film pattern forming step); and wet-etching the phase shift film 30 using the resist film pattern 50 as a mask to form a phase shift film pattern 30a on the transparent substrate 20 (a phase shift film pattern forming step).

[0114] Hereinafter, each step of the manufacturing process of the phase shift mask 100 according to the third and fourth embodiments will be described in detail.

[0115] Manufacturing process of the phase shift mask 100 according to the third embodiment

[0116] 1. First Resist Film Pattern Formation Step

[0117] In the first resist patterning step, a resist is first formed on the etching mask film 40 of the phase-shift mask blank 10 of Embodiment 1. The resist material used is not particularly limited. For example, any material that is sensitive to laser light having a wavelength selected from the 350 nm to 436 nm wavelength range, as described later, may be used. The resist may be either positive or negative.

[0118] Then, a desired pattern is drawn on the resist film using a laser having an arbitrary wavelength selected from the wavelength range of 350 nm to 436 nm. The pattern drawn on the resist film is the pattern formed on the phase shift film 30. Examples of the pattern drawn on the resist film include line and space patterns and hole patterns.

[0119] Then, the resist film is developed with a given developer, such as Figure 3 As shown in (a), a first resist film pattern 50 is formed on the etching mask film 40.

[0120] 2. First Etching Mask Film Pattern Formation Step

[0121] In the first etching mask film pattern forming step, etching mask film 40 is first etched using first resist film pattern 50 as a mask to form first etching mask film pattern 40a. Etching mask film 40 is formed of a chromium-based material containing chromium (Cr). The etchant used to etch etching mask film 40 is not particularly limited as long as it can selectively etch etching mask film 40. Specifically, an etchant containing ammonium cerium nitrate and perchloric acid can be used.

[0122] Then, use a resist stripping solution, or by ashing, such as Figure 3 As shown in (b), the first resist film pattern 50 is peeled off. In some cases, the following phase shift film pattern forming step may be performed without peeling off the first resist film pattern 50.

[0123] 3. Phase shift film pattern formation process

[0124] In the first phase shift film pattern forming step, the phase shift film 30 is wet-etched using the first etching mask film pattern 40a as a mask. Figure 3 A phase shift film pattern 30a is formed as shown in (c). Examples of the phase shift film pattern 30a include a line-and-space pattern and a hole pattern. The etchant used to etch the phase shift film 30 is not particularly limited as long as it can selectively etch the phase shift film 30. Examples include etchants containing ammonium fluoride, phosphoric acid, and hydrogen peroxide, and etchants containing ammonium bifluoride and hydrogen peroxide.

[0125] To ensure a good cross-sectional shape of the phase shift film pattern 30a, wet etching is preferably performed for a time (overetching time) longer than the time required to expose the transparent substrate 20 through the phase shift film pattern 30a (the appropriate etching time). The overetching time is preferably set to the appropriate etching time plus 10 to 20% of the appropriate etching time, taking into account the effects on the transparent substrate 20.

[0126] 4. Second Resist Film Pattern Formation Step

[0127] In the second resist film pattern forming step, a resist film is first formed to cover the first etching mask film pattern 40a. The resist film material used is not particularly limited. For example, any material that is sensitive to laser light having a wavelength selected from the 350 nm to 436 nm wavelength range, as described later, will suffice. The resist film may be either positive or negative.

[0128] Next, a desired pattern is drawn on the resist film using a laser beam having a wavelength selected from the range of 350 nm to 436 nm. The pattern drawn on the resist film may include a light-shielding pattern that shields the outer periphery of the region where the pattern 30 a is formed on the phase shift film, or a light-shielding pattern that shields the central portion of the phase shift film pattern 30 a. It should be noted that, depending on the transmittance of the phase shift film 30 to exposure light, the pattern drawn on the resist film may also include a pattern without the light-shielding pattern that shields the central portion of the phase shift film pattern 30 a.

[0129] Then, the resist film is developed with a given developer, such as Figure 3 As shown in (d), a second resist film pattern 60 is formed on the first etching mask film pattern 40a.

[0130] 5. Second Etching Mask Film Pattern Formation Step

[0131] In the second etching mask film pattern forming step, the first etching mask film pattern 40a is etched using the second resist film pattern 60 as a mask. Figure 3 As shown in FIG. 4(e), a second etching mask film pattern 40b is formed. The first etching mask film pattern 40a is formed of a chromium-based material containing chromium (Cr). The etchant used to etch the first etching mask film pattern 40a is not particularly limited as long as it can selectively etch the first etching mask film pattern 40a. For example, an etchant containing ammonium cerium nitrate and perchloric acid can be used.

[0132] Then, the second resist film pattern 60 is removed using a resist stripping solution or by ashing.

[0133] Thus, it is possible to obtain the phase shift mask 100. That is, the transfer pattern included in the phase shift mask 100 of the third embodiment may include the phase shift film pattern 30a and the second etching mask film pattern 40b.

[0134] It should be noted that, while the above description describes the case where the etching mask film 40 has the function of blocking the transmission of exposure light, if the etching mask film 40 only functions as a hard mask when etching the phase shift film 30, the second resist film pattern forming step and the second etching mask film pattern forming step are omitted. Instead, the first etching mask film pattern is removed after the phase shift film pattern forming step to produce the phase shift mask 100. In other words, the transfer pattern of the phase shift mask 100 of Embodiment 3 may consist solely of the phase shift film pattern 30a. This transfer pattern may further include other film patterns. Examples of such other films include a film that suppresses reflection and a conductive film.

[0135] According to the method for manufacturing the phase shift mask 100 of Embodiment 3, by using the phase shift mask blank 10 of Embodiment 1, etching time can be shortened, and a phase shift film pattern 30a having excellent cross-sectional shape, line edge roughness, and chemical resistance can be formed without causing damage to the transparent substrate 20 by the wet etching solution, which would otherwise reduce the transmittance of the transparent substrate 20. Therefore, a phase shift mask 100 capable of accurately transferring a high-definition phase shift film pattern 30a can be manufactured. The phase shift mask 100 manufactured in this manner can cope with the miniaturization of line and space patterns and contact holes.

[0136] Manufacturing process of the phase shift mask 100 according to the fourth embodiment

[0137] 1. Resist film pattern forming process

[0138] In the resist film pattern forming process, first, a resist film is formed on the phase shift film 30 of the phase shift mask blank 10 of embodiment 2. The resist film material used is the same as that described in embodiment 3. It should be noted that, in order to achieve good adhesion with the phase shift film 30, the phase shift film 30 may be subjected to surface modification treatment as needed before forming the resist film. After the resist film is formed in the same manner as described above, a desired pattern is drawn on the resist film using a laser having any wavelength selected from the wavelength range of 350nm to 436nm. Then, the resist film is developed with a given developer, such as Figure 4 As shown in (a), a resist film pattern 50 is formed on the phase shift film 30.

[0139] 2. Phase shift film pattern formation process

[0140] In the phase shift film pattern forming process, the phase shift film 30 is etched using the resist film pattern as a mask. Figure 4As shown in (b), a phase shift film pattern 30a is formed. This forms a transfer pattern. The etching solution and over-etching time for etching the phase shift film pattern 30a and the phase shift film 30 are the same as those described in the third embodiment.

[0141] Then, the resist film pattern 50 is peeled off using a resist stripping solution or by ashing ( Figure 4 (c)).

[0142] Thus, the phase shift mask 100 can be obtained. It should be noted that the transfer pattern of the phase shift mask of this embodiment may consist of only the phase shift film pattern 30a, or may further include other film patterns. Examples of other films include anti-reflection films and conductive films.

[0143] According to the method for manufacturing the phase shift mask 100 of the fourth embodiment, by using the phase shift mask blank 10 of the second embodiment, etching time can be shortened, and a phase shift film pattern 30a having excellent cross-sectional shape, line edge roughness, and chemical resistance can be formed without causing damage to the transparent substrate 20 by the wet etching solution, which would otherwise reduce the transmittance of the transparent substrate 20. Therefore, a phase shift mask 100 capable of accurately transferring a high-definition phase shift film pattern 30a can be manufactured. The phase shift mask 100 manufactured in this manner can cope with the miniaturization of line and space patterns and contact holes.

[0144] Implementation method 5.

[0145] In Embodiment 5, a method for manufacturing a display device is described. The display device can be manufactured by a step (mask placement step) of using a phase shift mask 100 manufactured using the aforementioned phase shift mask blank 10 or by the aforementioned method for manufacturing the phase shift mask 100, and a step (exposure step) of transferring a transfer pattern including the phase shift film pattern 30a to a resist film on a display device substrate by exposure.

[0146] Hereinafter, each step will be described in detail.

[0147] 1. Placement process

[0148] In the placement step, the phase shift mask 100 manufactured in Embodiment 3 or 4 is placed on a mask stage of an exposure apparatus. Here, the phase shift mask 100 is arranged to face the resist film formed on the display device substrate via the projection optical system of the exposure apparatus.

[0149] 2. Pattern transfer process

[0150] In the pattern transfer process, exposure light is irradiated onto the phase shift mask 100, transferring the transfer pattern containing the phase shift film pattern 30a to the resist film formed on the display device substrate. The exposure light can be composite light containing multiple wavelengths selected from the 365nm to 436nm wavelength range, or monochromatic light selected by removing a wavelength range from the 365nm to 436nm wavelength range using a filter. For example, the exposure light can be composite light containing at least one of the i-line, h-line, and g-line, or i-line monochromatic light. Using composite light as the exposure light can increase the exposure light intensity and luminous flux, thereby reducing the manufacturing cost of the display device.

[0151] According to the method for manufacturing a display device of this fifth embodiment, a high-definition display device having a high resolution, a fine line and space pattern, and contact holes can be manufactured.

[0152] Example

[0153] Example 1

[0154] A. Phase shift mask blanks

[0155] In order to manufacture the phase shift mask blank 10 of Example 1, first, a synthetic quartz glass substrate of 1214 size (1220 mm×1400 mm) was prepared as the transparent substrate 20 .

[0156] Then, the synthetic quartz glass substrate is placed on a tray (not shown) with one main surface facing downward, and is transported into the chamber of the inline sputtering apparatus.

[0157] To form the phase shift film 30 on the other main surface of the transparent substrate 20, a mixed gas consisting of argon (Ar) and nitrogen (N2) was first introduced into the first chamber, where the sputtering gas pressure was set to 0.5 Pa. Next, a MoZrSiN-based phase shift film 30 containing molybdenum, zirconium, silicon, and nitrogen was formed on the main surface of the transparent substrate 20 by reactive sputtering using a MoZrSi target composed of a material having an atomic ratio of Mo:Zr:Si of 10:10:80. The atomic ratios in the target used for sputtering are merely examples and can be appropriately selected depending on the desired composition of the phase shift film 30.

[0158] Next, the transparent substrate 20 with the phase shift film 30 was transported into the second chamber. A mixed gas of argon (Ar) and nitrogen (N2) was introduced into the second chamber, and chromium nitride (CrN) containing chromium and nitrogen (15 nm thick) was formed on the phase shift film 30 by reactive sputtering. Next, with a predetermined vacuum level in the third chamber, a mixed gas of argon (Ar) and methane was introduced, and chromium carbide (CrC) containing chromium and carbon (60 nm thick) was formed on the CrN by reactive sputtering. Finally, a mixed gas of argon (Ar) and methane, and a mixed gas of nitrogen (N2) and oxygen (O2) were introduced into the fourth chamber, also set to a predetermined vacuum level, and chromium oxycarbonitride (CrCON) containing chromium, carbon, oxygen, and nitrogen (30 nm thick) was formed on the CrC by reactive sputtering. In this manner, an etching mask film 40 having a stacked structure of CrN, CrC, and CrCON layers was formed on the phase shift film 30.

[0159] In this manner, the phase shift mask blank 10 in which the phase shift film 30 and the etching mask film 40 are formed on the transparent substrate 20 is obtained.

[0160] The refractive index and extinction coefficient of the phase shift film 30 of the obtained phase shift mask blank 10 were measured using a substrate with a phase shift film (dummy substrate) in which the phase shift film 30 was formed on the main surface of a synthetic quartz glass substrate and mounted on the same tray.

[0161] 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).

[0162] The transmittance and retardation of the surface of the phase shift film 30 of the obtained phase shift mask blank 10 were measured using an MPM-100 manufactured by Lasertec. The transmittance and retardation of the phase shift film 30 were measured using a substrate with a phase shift film (dummy substrate) mounted on the same tray as above, in which the phase shift film 30 was formed on the main surface of a synthetic quartz glass substrate. The substrate with a phase shift film (dummy substrate) was removed from the chamber before forming the etching mask film 40, and the transmittance and retardation of the phase shift film 30 were measured. The results showed a transmittance of 50% (wavelength: 405 nm), a retardation of 180° (wavelength: 405 nm), a back surface reflectance of 15.4% (wavelength: 405 nm), and a surface reflectance of 21.3% (wavelength: 405 nm).

[0163] Furthermore, the composition analysis in the depth direction of the phase shift film 30 of the obtained phase shift mask blank 10 was performed by X-ray photoelectron spectroscopy (XPS).

[0164] XPS depth-direction composition analysis of the phase shift mask blank 10 revealed that, except for the composition gradient regions at the interface between the transparent substrate 20 and the phase shift film 30 and the interface between the phase shift film 30 and the etching mask film 40, the content ratios of the constituent elements in the phase shift film 30 were essentially constant along the depth direction: Mo was 3 atomic %, Zr was 5 atomic %, Si was 42 atomic %, N was 47 atomic %, and O was 3 atomic %. Furthermore, the atomic ratio of molybdenum to zirconium was 1:1, falling within the range of Mo:Zr = 1:0.67 to 1:4. Furthermore, the content ratio of silicon relative to the total of molybdenum, zirconium, and silicon was 84 atomic %, falling within the range of [Si / (Mo+Zr+Si)] = 70 to 88 atomic %. It is believed that the presence of oxygen in the phase shift film 30 is due to the presence of trace amounts of oxygen in the chamber during film formation.

[0165] B. Phase-Shift Mask and Its Manufacturing Method

[0166] In order to manufacture the phase shift mask 100 using the phase shift mask blank 10 manufactured as described above, first, a photoresist film is applied on the etching mask film 40 of the phase shift mask blank 10 using a resist coating apparatus.

[0167] Then, through a heating / cooling process, a photoresist film with a film thickness of 520 nm was formed.

[0168] Then, a photoresist film was patterned using a laser drawing apparatus, and after a development / rinsing process, a resist film pattern having a hole pattern with a hole diameter of 1.5 μm was formed on the etching mask film.

[0169] Then, the etching mask film is wet-etched using a chromium etching solution containing ammonium cerium nitrate and perchloric acid using the resist film pattern as a mask, thereby forming a first etching mask film pattern 40 a .

[0170] Next, using the first etching mask film pattern 40a as a mask, the phase shift film 30 was wet-etched using a molybdenum silicide etchant prepared by diluting a mixture of ammonium bifluoride and hydrogen peroxide with pure water, thereby forming the phase shift film pattern 30a. This wet etching was performed with an overetch time of 10% to achieve a vertical cross-sectional shape and to form the desired fine pattern.

[0171] Then, the resist film pattern is peeled off.

[0172] Then, a photoresist film is applied using a resist coating apparatus so as to cover the first etching mask film pattern 40 a .

[0173] Then, through a heating / cooling process, a photoresist film with a film thickness of 520 nm was formed.

[0174] Then, a photoresist film is drawn using a laser drawing device, and after a development / rinsing process, a second resist film pattern 60 for forming a light-shielding band is formed on the first etching mask film pattern 40a.

[0175] Then, using the second resist film pattern 60 as a mask, the first etching mask film pattern 40 a formed in the transfer pattern formation region is wet-etched using a chromium etching solution containing ammonium cerium nitrate and perchloric acid.

[0176] Then, the second resist film pattern 60 is peeled off.

[0177] Thus, a phase shift mask 100 is obtained, wherein the transfer pattern forming area on the transparent substrate 20 has a phase shift film pattern 30a with an aperture of 1.5 μm, and a light shielding band composed of a stacked structure of the phase shift film pattern 30a and the etching mask film pattern 40b is formed on the transparent substrate 20.

[0178] The resulting phase-shift mask was observed in cross-section using a scanning electron microscope. The cross-sectional observation revealed that the edge of the phase-shift film pattern 30a of the phase-shift mask formed an angle of 76° with the main surface of the transparent substrate 20, indicating that the phase-shift film pattern 30a had a nearly vertical cross-sectional shape. Furthermore, the phase-shift film pattern 30a was observed from above, revealing a smooth, essentially linear edge, which was excellent. In other words, no obvious unevenness was observed at the edge of the phase-shift film pattern 30a when viewed from above. The phase-shift film pattern 30a formed in the phase-shift mask of Example 1 had a cross-sectional shape that fully exhibited the phase-shift effect. Furthermore, the surface of the transparent substrate 20 exposed after removal of the phase-shift film 30 was smooth, and the reduction in transmittance caused by the surface roughness of the transparent substrate 20 was negligible. Furthermore, electron beam diffraction observation of the resulting phase-shift mask 100 confirmed that it had an amorphous structure. Furthermore, no penetration of etching liquid 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 excellent chemical resistance was achieved. Consequently, a phase shift mask exhibiting an excellent phase shift effect was obtained for exposure light including light in the wavelength range of 313 nm to 500 nm, more specifically, for exposure light including a composite of at least one of i-line, h-line, and g-line.

[0179] Therefore, when the phase shift mask 100 of Example 1 is set on the mask stage of an exposure apparatus and exposed to a resist film transferred onto a display device substrate, fine patterns less than 2.0 μm can be transferred with high precision. Furthermore, by forming the phase shift film 30 (phase shift film pattern 30a) under a vacuum of 0.5 Pa or less, a dense film is formed, which is expected to improve light resistance under exposure light.

[0180] Examples 2 to 4.

[0181] A. Phase shift mask blanks

[0182] In Examples 2 to 4, phase shift mask blanks 10 and phase shift masks 100 were manufactured using the same structure and method as in Example 1, except for the phase shift film 30. In Examples 2 to 4, the atomic ratios of Mo, Zr, and Si in the sputtering target used to form the phase shift film 30 in Example 1 were appropriately adjusted. The film thickness was appropriately adjusted so that the transmittance of the phase shift film 30 at a wavelength of 405 nm was between 20% and 80%, and the phase difference was within the range of 160° to 200°.

[0183] The composition analysis of the obtained MoZrSiN-based phase shift film 30 was conducted in the same manner as in Example 1. As a result, the atomic ratios of Mo and Zr were as follows.

[0184] Example 2 Mo: Zr = 1.5: 1 (1: 0.67),

[0185] Example 3 Mo: Zr = 1:2,

[0186] Example 4 Mo: Zr = 1:4,

[0187] Thus, Examples 2 to 4 all fall within the range of Mo:Zr = 1:0.67 to 1:4. Furthermore, the content ratio of silicon relative to the total of molybdenum, zirconium, and silicon falls within the range of [Si / (Mo+Zr+Si)] = 70 to 88 atomic % in all Examples 2 to 4.

[0188] B. Phase-Shift Mask and Its Manufacturing Method

[0189] Phase shift masks 100 were fabricated in the same manner as in Example 1. The cross-sectional shape of the phase shift film pattern 30a was examined, and the surface condition of the transparent substrate 20 exposed after the phase shift film 30 was removed was also examined. The results showed that in Examples 2-4, the angle formed 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 observed in cross section exceeded 70°, and each phase shift film pattern 30a had a nearly perpendicular cross-sectional shape. Furthermore, the LER of these phase shift film patterns 30a was observed in the same manner as in Example 1. The results showed that the edges of the phase shift film patterns (hole patterns) 30a in Examples 2-4 were smooth, substantially linear, and excellent. In other words, no significant unevenness was observed on the edges of the phase shift film patterns 30a when viewed from above. The phase shift film patterns 30a formed in the phase shift masks of Examples 2-4 had cross-sectional shapes that fully exhibited the phase shift effect. In Examples 2-4, the surface of the transparent substrate 20 exposed after removal of the phase shift film 30 was smooth, with negligible reduction in transmittance due to surface roughness of the transparent substrate 20. Furthermore, electron beam diffraction observation of the resulting phase shift masks 100 confirmed an amorphous structure in all Examples 2-4. Furthermore, no infiltration of etching solutions 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, demonstrating excellent chemical resistance. Therefore, in all Examples 2-4, phase shift masks 100 exhibiting excellent phase shifting effects were obtained for exposure light comprising light in the wavelength range of 313 nm to 500 nm, more specifically, for exposure light comprising a composite of at least one of i-line, h-line, and g-line.

[0190] Therefore, when the phase shift masks 100 of Examples 2 to 4 are set on the mask stage of an exposure apparatus and exposed to a resist film transferred onto a display device substrate, fine patterns less than 2.0 μm can be transferred with high precision. Furthermore, by forming the phase shift film 30 (phase shift film pattern 30a) under a vacuum of 0.5 Pa or less, a dense film is formed, and it is expected that the light resistance to exposure light will also be improved.

[0191] Example 5.

[0192] A. Phase shift mask blanks

[0193] The phase-shift mask blank 10 of Example 5 reduces the backside reflectivity of the phase-shift film 30 under exposure light. In forming the phase-shift film 30 of Example 1, a mixed gas consisting of argon (Ar) and nitrogen (N2) was first introduced into the first chamber at a sputtering gas pressure of 0.5 Pa. A 105 nm thick MoZrSiN-based underlayer film containing molybdenum, zirconium, silicon, and nitrogen was then formed on the main surface of the transparent substrate 20 by reactive sputtering using a MoZrSi target composed of a material having an atomic ratio of Mo:Zr:Si of 10:10:80. It should be noted that the atomic ratios in the target used for sputtering are merely examples and can be appropriately selected depending on the desired composition of the phase-shift film 30.

[0194] Then, a mixed gas consisting of argon (Ar), nitrogen (N2), and nitric oxide (NO) was introduced into the second chamber at a sputtering gas pressure of 1.6 Pa. A 44 nm thick MoSiON-based upper film containing molybdenum, silicon, oxygen, and nitrogen was formed on the MoZrSiN-based lower film by reactive sputtering using a MoSi target made of a material with an atomic ratio of Mo:Si of 8:92. This formed a phase shift film 30 composed of a stacked film comprising the MoZrSiN-based lower film and the MoSiON-based upper film.

[0195] Next, an etching mask film 40 having a stacked structure of CrN, CrC, and CrCON layers was formed on the phase shift film 30 in the same manner as in Example 1, thereby obtaining a phase shift mask blank 10 having the phase shift film 30 and the etching mask film 40 formed on the transparent substrate 20 .

[0196] The refractive index and extinction coefficient of the lower layer film and the upper layer film constituting the phase shift film 30 of the obtained phase shift mask blank 10 were measured using a model substrate prepared and mounted on the same tray.

[0197] The results show that the refractive index n of the MoZrSiN-based lower layer is 2.45 (wavelength: 405 nm) and the extinction coefficient k is 0.11 (wavelength: 405 nm). The refractive index n of the MoSiN-based upper layer is 2.24 (wavelength: 405 nm) and the extinction coefficient k is 0.14 (wavelength: 405 nm).

[0198] The transmittance and retardation of the phase shift film 30 of the obtained phase shift mask blank 10 were measured in the same manner as in Example 1. The results showed a transmittance of 51% (wavelength: 405 nm), a retardation of 180° (wavelength: 405 nm), a back surface reflectance of 9.8% (wavelength: 405 nm), and a surface reflectance of 14.9% (wavelength: 405 nm).

[0199] In addition, similar to Example 1, the phase shift film 30 of the obtained phase shift mask blank 10 was subjected to depth-direction composition analysis using X-ray photoelectron spectroscopy (XPS). The XPS depth-direction composition analysis of the phase shift mask blank 10 revealed that, except for the composition gradient regions at the interface between the transparent substrate 20 and the phase shift film 30 and the interface between the phase shift film 30 and the etching mask film 40, the content ratios of the constituent elements in the phase shift film 30 were substantially constant along the depth direction. In the underlying film, Mo was 3 atomic %, Zr was 5 atomic %, Si was 42 atomic %, N was 47 atomic %, and O was 3 atomic %. Furthermore, the atomic ratio of molybdenum to zirconium was Mo:Zr = 1:1, falling within the range of Mo:Zr = 1:0.67 to 1:4. Furthermore, the content ratio of silicon relative to the total of molybdenum, zirconium, and silicon was 84 atomic %, falling within the range of [Si / (Mo+Zr+Si)] = 70 to 88 atomic %. The upper film contains 6 atomic % of Mo, 41 atomic % of Si, 47 atomic % of N, and 6 atomic % of O. It is to be noted that the lower film contains oxygen because a trace amount of oxygen exists in the chamber during film formation.

[0200] B. Phase-Shift Mask and Its Manufacturing Method

[0201] A phase shift mask 100 was fabricated in the same manner as in the above-mentioned embodiment, and the cross-sectional shape of the phase shift film pattern 30a and the surface condition of the transparent substrate 20 exposed after the phase shift film 30 was removed were examined. Cross-sectional observation revealed that the angle formed 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°, indicating a nearly perpendicular cross-sectional shape. Furthermore, the LER of the phase shift film pattern 30a was observed in the same manner as in Example 1. The results showed that the edge of the phase shift film pattern (hole pattern) 30a was smooth and substantially linear, indicating good quality. In other words, no significant unevenness was observed at the edge of the phase shift film pattern 30a when viewed from above. The phase shift film pattern 30a formed in the phase shift mask 100 of Example 5 had a cross-sectional shape that fully exhibited the phase shift effect. Furthermore, the surface of the transparent substrate 20 exposed after the phase shift film 30 was smooth, and the reduction in transmittance due to surface roughness of the transparent substrate 20 was negligible. Observation of the resulting phase shift mask 100 by electron beam diffraction confirmed its amorphous structure. Furthermore, no infiltration of etching solutions 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, demonstrating excellent chemical resistance. Consequently, a phase shift mask 100 exhibiting an excellent phase shift effect was obtained for exposure light comprising light in the wavelength range of 313 nm to 500 nm, more specifically, for exposure light comprising a composite of at least one of i-line, h-line, and g-line.

[0202] Therefore, when the phase shift mask 100 of Example 5 is set on the mask stage of an exposure apparatus and exposed to a resist film transferred onto a display device substrate, fine patterns less than 2.0 μm can be transferred with high precision. Furthermore, by forming the phase shift film 30 (phase shift film pattern 30a) under a vacuum of 0.5 Pa or less, a dense film is formed, and it is expected that the light resistance to exposure light will also be improved.

[0203] Comparative Example 1.

[0204] A. Phase shift mask blanks

[0205] In Comparative Example 1, a phase shift mask blank 10 and a phase shift mask 100 were manufactured using the same structure and method as in Example 1, except for the phase shift film 30. In Comparative Example 1, the atomic ratios of Mo, Zr, and Si in the sputtering target used to form the phase shift film 30 in Example 1 were appropriately adjusted. The film thickness was appropriately adjusted so that the transmittance of the phase shift film at a wavelength of 405 nm was between 20% and 80%, and the phase difference was within the range of 160° to 200°.

[0206] The composition analysis of the obtained MoZrSiN-based phase shift film 30 was conducted in the same manner as in Example 1. As a result, the atomic ratios of Mo and Zr were as follows.

[0207] Comparative Example 1

[0208] Mo: Zr=1:1, [Si / (Mo+Zr+Si)]=90 atomic%

[0209] Thus, Comparative Example 1 is within the range of Mo:Zr=1:0.67 to 1:4, but is outside the range of [Si / (Mo+Zr+Si)]=70 to 88 atomic %.

[0210] B. Phase-Shift Mask and Its Manufacturing Method

[0211] The phase shift mask 100 was produced in the same manner as in Example 1, and the cross-sectional shape of the phase shift film pattern 30 a and the surface condition of the transparent substrate 20 exposed after the phase shift film 30 was removed were confirmed.

[0212] As a result, in Comparative Example 1, the cross-sectional shape of the phase shift film pattern 30a was not significantly different from that of the other examples and was satisfactory. However, the surface of the transparent substrate 20 exposed after removal of the phase shift film 30 was rough and appeared cloudy to the naked eye. Therefore, the rough surface of the transparent substrate 20 significantly reduced the transmittance.

[0213] Therefore, it is predicted that when the phase shift mask 100 of Comparative Example 1 is set on a mask stage of an exposure apparatus and the resist film transferred onto a display device substrate is exposed, a fine pattern smaller than 2.0 μm cannot be transferred.

[0214] Comparative Example 2.

[0215] A. Phase shift mask blanks

[0216] In Comparative Example 2, a phase shift mask blank 10 and a phase shift mask 100 were manufactured using the same structure and method as in Example 1, except for the phase shift film 30. In Comparative Example 2, the atomic ratios of Mo, Zr, and Si in the sputtering target used to form the phase shift film 30 in Example 1 were appropriately adjusted. The film thickness was appropriately adjusted so that the transmittance of the phase shift film 30 at a wavelength of 405 nm was between 20% and 80%, and the phase difference was within the range of 160° to 200°.

[0217] The composition analysis of the obtained MoZrSiN-based phase shift film 30 was conducted in the same manner as in Example 1. As a result, the atomic ratios of Mo and Zr were as follows.

[0218] Comparative Example 2

[0219] Mo: Zr=1:1, [Si / (Mo+Zr+Si)]=65 atomic%

[0220] Thus, the ratio of Mo:Zr in Comparative Example 2 is within the range of 1:0.67 to 1:4, but is outside the range of [Si / (Mo+Zr+Si)]=70 to 88 atomic %.

[0221] B. Phase-Shift Mask and Its Manufacturing Method

[0222] The phase shift mask 100 was produced in the same manner as in Example 1, and the cross-sectional shape of the phase shift film pattern 30 a and the surface condition of the transparent substrate 20 exposed after the phase shift film 30 was removed were confirmed.

[0223] As a result, in Comparative Example 2, the surface of the transparent substrate 20 exposed after the phase shift film 30 was removed was smooth, and the decrease in transmittance due to the surface roughness of the transparent substrate 20 was negligible. However, the cross-sectional shape of the phase shift film pattern 30a was poor and could not achieve a cross-sectional shape that could fully exert the phase shift effect.

[0224] Therefore, it is predicted that when the phase shift mask 100 of Comparative Example 2 is set on a mask stage of an exposure apparatus and the resist film transferred onto a display device substrate is exposed, a fine pattern smaller than 2.0 μm cannot be transferred.

[0225] Comparative Example 3.

[0226] A. Phase shift mask blanks

[0227] In Comparative Example 3, a phase shift mask blank 10 and a phase shift mask 100 were manufactured using the same structure and method as in Example 1 except for the phase shift film 30. In Comparative Example 3, the atomic ratios of Mo, Zr, and Si in the sputtering target used for forming the phase shift film 30 in Example 1 were appropriately adjusted.

[0228] Composition analysis of the MoZrSiN-based phase shift film 30 obtained in the same manner as in Example 1 revealed that in Comparative Example 3, the atomic ratio of Mo:Zr was 2:1, outside the range of 1:0.67 to 1:4. On the other hand, the silicon content relative to the total of molybdenum, zirconium, and silicon was within the range of [Si / (Mo+Zr+Si)] = 70 to 88 atomic %.

[0229] B. Phase-Shift Mask and Its Manufacturing Method

[0230] The phase shift mask 100 was produced in the same manner as in Example 1, and the cross-sectional shape of the phase shift film pattern 30 a and the surface condition of the transparent substrate 20 exposed after the phase shift film 30 was removed were confirmed.

[0231] As a result, in Comparative Example 3, the surface of the transparent substrate 20 exposed after removal of the phase shift film 30 was smooth, and the decrease in transmittance due to the surface roughness of the transparent substrate 20 was negligible. Furthermore, the cross-sectional shape of the phase shift film pattern 30a was not significantly different from that of the other examples and was satisfactory. However, the transmittance at a wavelength of 405 nm was less than 15%, indicating insufficient transmittance. Even after adjusting the film thickness in the same manner as in the other examples and comparative examples, sufficient transmittance could not be achieved.

[0232] Therefore, it is predicted that when the phase shift mask 100 of Comparative Example 3 is set on a mask stage of an exposure apparatus and the resist film transferred onto a display device substrate is exposed, a fine pattern smaller than 2.0 μm cannot be transferred.

[0233] Comparative Example 4.

[0234] A. Phase shift mask blanks

[0235] In Comparative Example 4, a phase shift mask blank 10 and a phase shift mask 100 were manufactured using the same structure and method as in Example 1, except for the phase shift film 30. In Comparative Example 4, the atomic ratios of Mo, Zr, and Si in the sputtering target used to form the phase shift film in Example 1 were appropriately adjusted. The film thickness of the phase shift film 30 was appropriately adjusted so that the transmittance at a wavelength of 405 nm was between 20% and 80%, and the phase difference was within the range of 160° to 200°.

[0236] Composition analysis of the MoZrSiN-based phase shift film 30 obtained in the same manner as in Example 1 revealed that in Comparative Example 4, the atomic ratio of molybdenum to zirconium was Mo:Zr = 1:5, outside the range of 1:0.67 to 1:4. On the other hand, the silicon content relative to the total of molybdenum, zirconium, and silicon was within the range of [Si / (Mo+Zr+Si)] = 70 to 88 atomic %.

[0237] B. Phase-Shift Mask and Its Manufacturing Method

[0238] The phase shift mask 100 was produced in the same manner as in Example 1, and the cross-sectional shape of the phase shift film pattern and the surface condition of the transparent substrate 20 exposed after the phase shift film 30 was removed were confirmed.

[0239] As a result, in Comparative Example 4, the surface of the transparent substrate 20 exposed after removal of the phase shift film 30 was smooth, and the reduction in transmittance due to the surface roughness of the transparent substrate 20 was negligible. However, sufficient chemical resistance was not achieved, and the cross-sectional shape of the phase shift film pattern 30a was inferior to that of the other examples. Furthermore, both the surface reflectivity and back surface reflectivity at a wavelength of 405 nm were high, and sufficient transfer accuracy could not be achieved.

[0240] Therefore, it is predicted that when the phase shift mask 100 of Comparative Example 4 is set on the mask stage of an exposure apparatus and the resist film transferred onto the display device substrate is exposed, a fine pattern smaller than 2.0 μm cannot be transferred.

Claims

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

2. The photomask blank according to claim 1, wherein The phase shift film has the following optical properties: a transmittance of greater than 20% and less than 80% for a representative wavelength of exposure light, and a phase difference of greater than 160° and less than 200°, wherein the exposure light is composite light including i-line, h-line, and g-line, and the representative wavelength is any one of the i-line, h-line, and g-line.

3. The photomask blank according to claim 1 or 2, wherein: 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.

4. The photomask blank according to claim 3, wherein The upper layer is formed of a material having a lower refractive index than that of the lower layer and a higher extinction coefficient than that of the lower layer at a representative wavelength of exposure light, wherein the exposure light is a composite light including i-line, h-line and g-line, and the representative wavelength is any one of i-line, h-line and g-line.

5. The photomask blank according to claim 4, wherein The refractive index, extinction coefficient, and film thickness of each of the upper layer and the lower layer are set so that the back reflectivity of the phase shift film for a representative wavelength of exposure light is 15% or less, wherein the exposure light is a composite light including i-line, h-line, and g-line, and the representative wavelength is any one of the i-line, h-line, and g-line.

6. The photomask blank according to claim 1 or 2, wherein: An etching mask film having a different etching selectivity with respect to the phase shift film is provided on the phase shift film.

7. A method for manufacturing a photomask, the method comprising: A step of preparing a photomask blank according to any one of claims 1 to 5; as well as A process of forming a resist film on the phase shift film, and wet-etching the phase shift film using a resist film pattern formed by the resist film as a mask to form a phase shift film pattern on the transparent substrate.

8. A method for manufacturing a photomask, the method comprising: A step of preparing the 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 by the resist film as a mask to form an etching mask film pattern on the phase shift film; as well as The phase shift film is wet-etched using the etching mask film pattern as a mask to form a phase shift film pattern on the transparent substrate.

9. A method for manufacturing a display device, the method comprising: An exposure step in which the photomask obtained by the photomask manufacturing method according to claim 7 or 8 is placed on a mask stage of an exposure apparatus, and a transfer pattern including the phase shift film pattern formed on the photomask is transferred by exposure to a resist formed on a display device substrate.

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