Mask blank, transfer mask, and method for manufacturing display device

Abstract

To provide a mask blank by which adhesion between semi-translucent film and a resist film when performing patterning of a semi-translucent film by wet etching can be sufficiently secured, and the in-plane CD of a semi-translucent pattern after patterning the semi-translucent film by wet etching can be increased.SOLUTION: A mask blank is equipped with a thin film for transfer pattern formation on a translucent substrate, where the thin film contains chromium, silicon and nitrogen, an element contained in the thin film the most is chromium, the content of silicon in the thin film is 2.8 atom% or less, and the thin film has a columnar structure.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a mask blank, a transfer mask, and a method for manufacturing a display device. [Background technology]

[0002] 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 achieving higher resolution and faster display speeds. One of the elements required for achieving this higher resolution and faster display speed is the fabrication of electronic circuit patterns, such as elements and wiring, with fine, highly dimensional accuracy. Photolithography is often used to pattern the electronic circuits for these display devices. This has created a need for transfer masks for display device manufacturing that have fine, highly accurate patterns formed on them.

[0003] For example, Patent Document 1 discloses a gray-tone mask having a pattern consisting of light-shielding portions, light-transmitting portions, and semi-light-transmitting portions, and a gray-tone mask blank for use in manufacturing the same. This mask blank has a light-shielding film pattern and a semi-light-transmitting film formed on the light-shielding film pattern on a transparent substrate, with the light-shielding film made of a material containing chromium (Cr) as a main component, and the semi-light-transmitting film made of a material containing chromium (Cr) and nitrogen (N). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2006-268035 Summary of the Invention [Problem to be solved by the invention]

[0005] Chromium-based materials are widely used as materials for semi-transparent films used in semi-transparent patterns of transfer masks such as multi-tone masks. In general, in the manufacture of transfer masks used in the FPD manufacturing process, wet etching is used in the etching process to form patterns in thin films on a transparent substrate.

[0006] Generally, the semi-transparent pattern of a multi-tone mask is required to transmit exposure light at a predetermined transmittance. When high transmittance is required for the semi-transparent pattern, approaches taken include making the semi-transparent film thinner or using a material that has lower light-blocking performance (smaller extinction coefficient k for exposure light) for the semi-transparent film. Chromium metal films have a high light-blocking property against exposure light, making them unsuitable for semi-transparent films that must transmit exposure light at a specified transmittance. For this reason, materials containing nitrogen in chromium (chromium nitride-based materials) are often used for semi-transparent films. However, thin films of chromium nitride-based materials have the problem that, depending on the optical properties required for the thin film, such as transmittance, it is difficult to control the in-plane CD (increase the in-plane CD) when wet-etching the thin film to form a thin film pattern, as described below.

[0007] The semi-transparent patterns in multi-tone masks have relatively large variations in pattern density within the surface. If the thickness of a semi-transparent film made of chromium nitride material is made thinner to increase its transmittance, a problem occurs when the semi-transparent film is patterned by wet etching: the CD drops significantly in the relatively sparse areas of the pattern. This is because significantly reducing the thickness of the semi-transparent film significantly shortens the etching time during wet etching, making etching control more difficult.

[0008] On the other hand, even if a chromium nitride-based semi-transparent film with a higher nitrogen content is used to achieve higher transmittance, when the semi-transparent film is patterned by wet etching, the CD drops significantly in the relatively sparse areas of the pattern. This is because the wet etching rate becomes too fast when the semi-transparent film is made of a chromium nitride-based semi-transparent film with a high nitrogen content, making etching control difficult.

[0009] Furthermore, in order to form a transfer pattern with a good cross-sectional shape in a transfer mask, it is also necessary to ensure sufficient adhesion between the semi-transparent film and the resist film.

[0010] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a mask blank, a transfer mask, and a method for manufacturing a display device that can ensure sufficient adhesion between a semi-transparent film and a resist film when patterning the semi-transparent film by wet etching, and that can increase the in-plane CD of the semi-transparent pattern after patterning the semi-transparent film by wet etching. [Means for solving the problem]

[0011] The present inventors have conducted extensive research into ways to solve these problems. As mentioned above, conventional approaches to increasing the transmittance of semi-transparent films have difficulty increasing the in-plane CD of semi-transparent patterns. After extensive research, the inventors investigated the possibility of reducing the wet etching rate by incorporating a small amount of silicon into semi-transparent films made of chromium nitride-based materials. However, while the etching rate could be reduced, they discovered a new problem: semi-transparent films made of silicon-containing chromium nitride-based materials have lower adhesion to resist films than semi-transparent films made of silicon-free chromium nitride-based materials. Specifically, during wet etching using a resist pattern as an etching mask, the etchant penetrates the interface between the resist pattern and the semi-transparent film, and etching of the semi-transparent film in the areas covered by the resist pattern proceeds from the surface (i.e., toward the interface between the resist pattern and the semi-transparent film), resulting in an abnormal pattern formation on the semi-transparent film. Depending on the adhesion of the semi-transparent film to the resist film, the resist pattern may even detach from the semi-transparent film during wet etching.

[0012] The present inventors conducted further intensive research to improve the adhesion of a semi-transparent film made of a silicon-containing chromium nitride-based material to a resist film. As a result, they found that by making the internal structure of the semi-transparent film a columnar structure, it is possible to prevent a decrease in adhesion between the semi-transparent film and the resist film. However, they also found that if the silicon content of the semi-transparent film exceeds 2.8 atomic %, sufficient adhesion between the semi-transparent film and the resist film cannot be obtained. They then found that by combining a columnar internal structure with a silicon content of 2.8 atomic % or less, sufficient adhesion between the semi-transparent film and the resist film can be ensured, and the in-plane CD of the semi-transparent pattern after patterning the semi-transparent film by wet etching can be increased. The present invention has been made as a result of the above-mentioned intensive studies, and has the following features.

[0013] (Configuration 1) A mask blank comprising a thin film for forming a transfer pattern on a light-transmitting substrate, the thin film contains chromium, silicon, and nitrogen; the element most abundant in the thin film is chromium; The silicon content of the thin film is 2.8 atomic % or less, The thin film has a columnar structure A mask blank characterized by:

[0014] (Configuration 2) The mask blank according to configuration 1, wherein the ratio of the silicon content to the chromium content in the thin film is 0.035 or less. (Configuration 3) The mask blank according to configuration 1, wherein the chromium content in the thin film is 50 atomic % or more.

[0015] (Configuration 4) The mask blank according to configuration 1, wherein the nitrogen content in the thin film is 25 atomic % or more.

[0016] (Configuration 5) The mask blank according to configuration 1, wherein the total content of chromium, silicon, and nitrogen in the thin film is 90 atomic % or more. (Configuration 6) A mask blank according to configuration 1, wherein the columnar structure of the thin film is a structure in which columnar particles extending in the film thickness direction are formed across the surface of the light-transmitting substrate.

[0017] (Configuration 7) The mask blank according to configuration 6, wherein the thin film has a portion where the columnar particles have a relatively high density and a portion where the density is relatively low and sparse.

[0018] (Configuration 8) The mask blank according to configuration 1, wherein the thin film has a transmittance of 3% or more for light with a wavelength of 365 nm. (Configuration 9) A mask blank comprising a thin film having a transfer pattern formed on a light-transmitting substrate, the thin film contains chromium, silicon, and nitrogen; the element most abundant in the thin film is chromium; The silicon content of the thin film is 2.8 atomic % or less, The thin film has a columnar structure A transfer mask characterized by:

[0019] (Configuration 10) The transfer mask according to configuration 9, wherein the ratio of the silicon content to the chromium content in the thin film is 0.035 or less.

[0020] (Configuration 11) The transfer mask according to configuration 9, wherein the chromium content in the thin film is 50 atomic % or more.

[0021] (Configuration 12) The transfer mask according to configuration 9, wherein the nitrogen content in the thin film is 25 atomic % or more. (Configuration 13) The transfer mask according to configuration 9, wherein the total content of chromium, silicon, and nitrogen in the thin film is 90 atomic % or more.

[0022] (Configuration 14) The transfer mask according to configuration 9, wherein the columnar structure of the thin film is a structure in which columnar particles extending in the film thickness direction are formed across the surface of the light-transmitting substrate.

[0023] (Configuration 15) The transfer mask according to configuration 14, wherein the thin film has portions where the columnar particles are relatively dense and portions where the density is relatively low. (Configuration 16) The transfer mask according to configuration 9, wherein the thin film has a transmittance of 3% or more for light with a wavelength of 365 nm. (Configuration 17) 17. A method for manufacturing a display device, comprising an exposure step of placing the transfer mask according to any one of configurations 9 to 16 on a mask stage of an exposure device, and exposing and transferring the transfer pattern formed on the transfer mask to a resist formed on a display device substrate. [Effects of the Invention]

[0024] The mask blank according to the present invention can ensure sufficient adhesion between the semi-transparent film and the resist film when patterning the semi-transparent film by wet etching, and can also provide a mask blank that can increase the in-plane CD of the semi-transparent pattern after patterning the semi-transparent film by wet etching.

[0025] Furthermore, the transfer mask according to the present invention can be a transfer mask having a transfer pattern with good transfer accuracy.

[0026] Furthermore, according to the method for manufacturing a display device of the present invention, the display device is manufactured using the above-described transfer mask, which allows the display device to be manufactured with a high yield. [Brief explanation of the drawings]

[0027] [Figure 1] FIG. 1 is a schematic diagram showing a film configuration of a mask blank according to a first embodiment. [Figure 2] FIG. 10 is a schematic diagram showing a film configuration of a mask blank according to a second embodiment. [Figure 3] FIG. 10 is a schematic diagram showing a transfer mask according to a third embodiment. [Figure 4] FIG. 10 is a schematic diagram showing a transfer mask according to a fourth embodiment. [Figure 5] 1 is a cross-sectional photograph of a transfer mask according to Example 1. [Figure 6] 10 is a cross-sectional photograph of a transfer mask according to Example 2. [Figure 7] 10 is a cross-sectional photograph of a transfer mask according to Example 3. [Figure 8] 10 is a cross-sectional photograph of a transfer mask according to Example 4. [Figure 9] 1 is a cross-sectional photograph of a transfer mask of Comparative Example 1. [Figure 10] 10 is a cross-sectional photograph of a transfer mask of Comparative Example 2. [Figure 11] 1 is a graph showing the relationship between the nitrogen content and the etching rate for Examples 1 to 3 and Comparative Example 3. DETAILED DESCRIPTION OF THE INVENTION

[0028] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that the following embodiments are one form for embodying the present invention and are not intended to limit the scope of the present invention. Note that in the drawings, the same or equivalent parts are given the same reference numerals, and their description may be simplified or omitted.

[0029] Embodiment 1.2. In the first and second embodiments, a mask blank will be described. 1 and 2 are schematic diagrams showing the film configuration of multi-tone mask blanks 10A and 10B (hereinafter sometimes simply referred to as "mask blank 10") according to embodiments 1 and 2. These multi-tone mask blanks 10A and 10B are used to manufacture multi-tone masks 100A and 100B (hereinafter sometimes simply referred to as "transfer mask 100") having light-transmitting portions 11, semi-light-transmitting portions 12, and light-shielding portions 13 shown in FIGS. A mask blank 10A shown in FIG. 1 includes a light-transmitting substrate 1, a semi-light-transmitting film 2 formed on the light-transmitting substrate 1, and a light-shielding film 3 formed on the semi-light-transmitting film 2.

[0030] The light-transmitting substrate 1 is transparent to the exposure light. The light-transmitting substrate 1 has a transmittance of 85% or more, preferably 90% or more, to the exposure light, assuming no surface reflection loss. The light-transmitting substrate 1 is made of a material containing silicon and oxygen, and can be made of a glass material such as synthetic quartz glass, quartz glass, aluminosilicate glass, soda-lime glass, or low-thermal expansion glass (SiO2-TiO2 glass, etc.). When the light-transmitting substrate 1 is made of low-thermal expansion glass, it is possible to suppress positional changes of the semi-transmitting pattern due to thermal deformation of the light-transmitting substrate 1. Furthermore, the light-transmitting substrate 1 used in display devices is generally a rectangular substrate, and the length of the short side of the light-transmitting substrate is 300 mm or more. The present invention provides a multi-tone mask blank that can provide a transfer mask that can stably transfer a fine semi-transmitting pattern formed on a light-transmitting substrate, even if the short side of the light-transmitting substrate is large and 300 mm or more in length.

[0031] The semi-transparent film 2 is a thin film for forming a transfer pattern. The semi-transparent film 2 contains chromium, silicon, and nitrogen. The most abundant element in the semi-transparent film 2 is chromium. The silicon content of the semi-transparent film 2 is 2.8 atomic % or less, and the semi-transparent film 2 has a columnar structure. The chromium content in the semi-transparent film 2 is preferably 50 atomic % or more, and the chromium content in the semi-transparent film 2 is preferably 90 atomic % or less. The ratio of the silicon content to the chromium content in the semi-transparent film 2 is preferably 0.035 or less. The ratio of the silicon content to the chromium content in the semi-transparent film 2 is preferably 0.005 or more, and more preferably 0.01 or more. The silicon content in the semi-transparent film 2 is more than 0 atomic %, more preferably 1 atomic % or more, and even more preferably 1.5 atomic %.

[0032] The nitrogen content in the semi-transparent film 2 is preferably 25 atomic % or more, more preferably 30 atomic % or more, and preferably less than 50 atomic %, more preferably 45 atomic % or less. The total content of chromium, silicon, and nitrogen in the semi-transparent film 2 is preferably 90 atomic % or more, more preferably 95 atomic % or more, and is preferably 100 atomic % or less.

[0033] In addition to the above-mentioned nitrogen, the semi-transparent film 2 may contain other light element components such as oxygen, carbon, and helium for the purpose of reducing film stress and controlling the wet etching rate. In particular, oxygen, which is a light element component, has the effect of lowering the extinction coefficient compared to nitrogen, which is also a light element component, and is therefore preferable in that it allows the content of other light element components (such as nitrogen) to be reduced in order to obtain the desired transmittance, and also effectively reduces the reflectance of the front and back surfaces of the semi-transparent film 2. The oxygen content in the semi-transparent film 2 is preferably 1 atomic % or more. Furthermore, the oxygen content in the semi-transparent film 2 is preferably 10 atomic % or less. The semi-transparent film 2 has at least the function of adjusting the transmittance of the exposure light. The semi-transparent film 2 can be formed by sputtering.

[0034] The semitransparent film 2 has a columnar structure. This columnar structure can be confirmed by cross-sectional SEM observation of the semitransparent film 2. That is, the columnar structure in the present invention refers to a state in which particles of a chromium-based silicide compound containing chromium, silicon, and nitrogen that constitute the semitransparent film 2 have a columnar particle structure extending in the film thickness direction of the semitransparent film 2 (the direction in which the particles are deposited). In the present application, a columnar particle is defined as one whose length in the film thickness direction is longer than its length in the perpendicular direction. That is, the semitransparent film 2 has columnar particles extending in the film thickness direction formed across the surface of the translucent substrate 1. Furthermore, by adjusting the film formation conditions (such as sputtering voltage), the semitransparent film 2 is formed so as to have a relatively high-density columnar particle portion and a sparse portion (hereinafter sometimes simply referred to as a "sparse portion") that is relatively lower in density than the columnar particles. In order to effectively suppress side etching during wet etching and further improve the cross-sectional shape of the pattern, the semitransparent film 2 preferably has a columnar structure in which columnar particles extending in the film thickness direction are irregularly formed in the film thickness direction. More preferably, the columnar particles in the semitransparent film 2 have irregular lengths in the film thickness direction. The sparse portions of the semitransparent film 2 are preferably formed continuously in the film thickness direction. Furthermore, the sparse portions of the semitransparent film 2 are preferably formed intermittently in a direction perpendicular to the film thickness direction.

[0035] The transmittance of the semi-transparent film 2 for the exposure light satisfies the value required for the semi-transparent film 2. The transmittance of the semi-transparent film 2 is preferably 3% or more, more preferably 4% or more, and even more preferably 5% or more for light of a predetermined wavelength contained in the exposure light (for example, light with a wavelength of 365 nm, hereinafter referred to as the representative wavelength). Furthermore, the transmittance of the semi-transparent film 2 is more preferably 70% or less, even more preferably 50% or less for the representative wavelength. When the exposure light is a composite light containing light in the wavelength range of 313 nm or more and 436 nm or less, the semi-transparent film 2 has the above-mentioned transmittance for light of a representative wavelength contained in that wavelength range. For example, when the exposure light is a composite light containing i-line, h-line, and g-line, the semi-transparent film 2 has the above-mentioned transmittance for any of the i-line, h-line, and g-line. The transmittance can be measured using a phase shift amount measuring device or the like.

[0036] This semi-transparent film 2 may be composed of multiple layers or a single layer. A semi-transparent film 2 composed of a single layer is preferable because interfaces are less likely to be formed in the semi-transparent film 2 and the cross-sectional shape is easier to control. On the other hand, a semi-transparent film 2 composed of multiple layers is preferable because it is easier to form the film. Furthermore, this semi-transparent film 2 may be a compositionally graded film in which the silicon content decreases in the film thickness direction.

[0037] The light-shielding film 3 is disposed above the semi-transparent film 2 and functions to block the transmission of exposure light. The light-shielding film 3 is preferably made of a chromium-based material containing chromium (Cr). In this case, however, an etching stopper film 4 made of a material with a different etching selectivity from the semi-transparent film 2 and the light-shielding film 3 must be provided between them. The etching stopper film 4 is preferably made of, for example, a transition metal silicide-based material mainly composed of silicon. The light-shielding film 3 is more preferably made of a material containing chromium but substantially not containing silicon. "Substantially not containing silicon" means that the silicon content is less than 1 atomic %. More specifically, the chromium-based material may be a material composed of chromium (Cr) alone, or a material containing chromium (Cr) and at least one of oxygen (O), nitrogen (N), and carbon (C). On the other hand, the light-shielding film 3 may be made of a material with a different etching selectivity from the semi-transparent film 2 (for example, a transition metal silicide-based material mainly composed of silicon). In this case, the etching stopper film 4 is not necessary.

[0038] In the portion (light-shielding portion 13) where the semi-transparent film 2, the etching stopper film 4, and the light-shielding film 3 are laminated, the optical density to the exposure light 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.

[0039] The light-shielding film 3 may consist of a single film with a uniform composition depending on the function, or may consist of multiple films with different compositions, or may consist of a single film whose composition changes continuously in the thickness direction.

[0040] 1 has an etching stopper film 4 and a light-shielding film 3 on a semi-transparent film 2, but the present invention can also be applied to a multi-tone mask blank that has an etching stopper film 4 and a light-shielding film 3 on a semi-transparent film 2 and a resist film on the light-shielding film 3. Furthermore, the mask blank of the present invention is not limited to a multi-tone mask blank, but may also be a transfer mask blank that has a semi-transparent film 2 on a light-transmitting substrate 1 (the same applies to the mask blank shown in FIG. 2).

[0041] Next, a multi-tone mask blank 10B according to the second embodiment will be described with reference to FIG. The mask blank 10B shown in Fig. 2 comprises a light-transmitting substrate 1 and a semi-transparent film 2 formed on the light-transmitting substrate 1, and a light-shielding pattern 3B between the light-transmitting substrate 1 and the semi-transparent film 2. The configurations of the light-transmitting substrate 1 and the semi-transparent film 2 are the same as those in the first embodiment, and therefore, description thereof will be omitted where appropriate. The light-shielding pattern 3B is disposed on the main surface of the light-transmitting substrate 1. The light-shielding pattern 3B has the function of blocking the transmission of exposure light. The material for forming the light-shielding pattern 3B is not particularly limited as long as it has the function of blocking the transmission of exposure light. For example, a chromium-based material can be used. Examples of the chromium-based material include chromium (Cr) and chromium-based materials containing chromium (Cr) and at least one of carbon (C) and nitrogen (N). Other examples include chromium-based materials containing chromium (Cr) and at least one of oxygen (O) and fluorine (F), or chromium-based materials containing chromium (Cr) and at least one of carbon (C) and nitrogen (N) and further containing at least one of oxygen (O) and fluorine (F). For example, examples of the material for forming the light-shielding pattern 3B include Cr, CrC, CrN, and CrCN. The light-shielding pattern 3B can be formed by patterning a light-shielding film formed by sputtering, by etching.

[0042] In the portion where the semi-transparent film 2 and the light-shielding pattern 3B are laminated, the optical density with respect to the exposure light is preferably 3 or more, and more preferably 3.5 or more. The optical density can be measured using a spectrophotometer or an OD meter.

[0043] The light-shielding pattern 3B may consist of a single film with a uniform composition, or may consist of multiple films with different compositions, or may consist of a single film whose composition changes continuously in the thickness direction.

[0044] A resist film may be provided on the semi-transparent film 2.

[0045] Next, a method for manufacturing the mask blank 10 according to the first and second embodiments will be described. 1. Preparation process In the preparation step, when the mask blank 10A shown in FIG. 1 is manufactured, first, a light-transmitting substrate 1 is prepared. 2, a light-shielding film made of, for example, a chromium-based material is formed on the light-transmitting substrate 1 by sputtering. A resist pattern is then formed on the light-shielding film, and the light-shielding film is etched using the resist pattern as a mask to form the light-shielding pattern 3B. The resist pattern is then peeled off.

[0046] 2. Semi-transparent film formation process In the semi-transparent film forming step, when the mask blank 10A shown in FIG. 1 is manufactured, the semi-transparent film 2 containing chromium, silicon, and nitrogen is formed on the transparent substrate 1 by sputtering. When manufacturing the mask blank 10B shown in Figure 2, a semi-transparent film 2 containing chromium, silicon, and nitrogen is formed on a light-transmitting substrate 1 on which a light-shielding pattern 3B is formed, so as to cover the light-shielding pattern 3B and the exposed surface of the light-transmitting substrate 1. The semi-transparent film 2 is formed using a sputtering target, such as a mixed sintered target containing chromium and silicon, the main components of the material constituting the semi-transparent film 2, in a sputtering gas atmosphere consisting of a mixture 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 activated 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 semi-transparent film 2 can have a columnar structure by using a lower sputtering power (voltage) in the deposition chamber during sputtering than when a semi-transparent film 2 having an ultrafine crystalline structure or an amorphous structure is deposited under the same sputtering gas atmosphere conditions (the specific sputtering power varies depending on the deposition apparatus). This columnar structure ensures sufficient adhesion between the semi-transparent film and a resist film during pattern formation, as described below.

[0047] The composition and thickness of the semi-transparent film 2 are adjusted so that the semi-transparent film 2 has the above-mentioned transmittance (when the semi-transparent film 2 is a phase shift film, it is adjusted so that the semi-transparent film 2 has the above-mentioned transmittance and a desired phase difference (for example, a phase difference in the range of 150 to 210 degrees)). The composition of the semi-transparent film 2 can be controlled by the content ratio of elements constituting the sputtering target (for example, the ratio of the chromium content to the silicon content), the composition and flow rate of the sputtering gas, the gas pressure in the film formation chamber, etc. The thickness of the semi-transparent film 2 can be controlled by the sputtering power, sputtering time, etc. Furthermore, the semi-transparent film 2 is preferably formed using an in-line sputtering apparatus. When the sputtering apparatus is an in-line sputtering apparatus, the thickness of the semi-transparent film 2 can also be controlled by the substrate transport speed. In this way, the composition and thickness of the semi-transparent film 2 are controlled.

[0048] When the semi-transparent film 2 is made of a single film, the above-described film formation process is performed only once by appropriately adjusting the composition and flow rate of the sputtering gas. When the semi-transparent film 2 is made of multiple films with different compositions, the above-described film formation process is performed multiple times by appropriately adjusting the composition and flow rate of the sputtering gas. The semi-transparent film 2 may be formed using a sputtering target having a different content ratio of elements that make up the sputtering target. When the film formation process is performed multiple times, the sputtering power applied to the sputtering target may be changed for each film formation process.

[0049] In this way, the mask blank 10B of the embodiment 2 is obtained. The mask blank 10A of the embodiment 1 is manufactured by further performing the following etching stopper film forming step and light-shielding film forming step.

[0050] 3. Etching stopper film formation process After the semi-transparent film forming step, the etching stopper film 4 is formed by sputtering on the semi-transparent film 2. The etching stopper film 4 is preferably formed using an in-line sputtering device. The etching stopper film 4 is formed using a sputtering target containing a transition metal and silicon in a sputtering gas atmosphere consisting of an inert gas containing at least one gas selected from the group consisting of helium gas, neon gas, argon gas, krypton gas, and xenon gas, or a sputtering gas atmosphere consisting of a mixed gas of an inert gas containing at least one gas 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 gas selected from the group consisting of oxygen gas, nitrogen gas, nitric oxide gas, nitrogen dioxide gas, carbon dioxide gas, and a fluorine-based gas.

[0051] 4. Light shielding film formation process After the etching stopper film formation step, the light-shielding film 3 is formed on the etching stopper film 4 by a sputtering method. The light-shielding film 3 is preferably formed using an in-line sputtering device. When the sputtering device is an in-line sputtering device, the thickness of the light-shielding film 3 can also be controlled by the transport speed of the light-transmitting substrate 1. The light-shielding film 3 is formed using a sputtering target containing chromium or a chromium compound (e.g., chromium oxide, chromium nitride, chromium carbide, chromium oxynitride, chromium oxynitride carbide, etc.) in a sputtering gas atmosphere consisting of an inert gas containing at least one selected from the group consisting of helium gas, neon gas, argon gas, krypton gas, and xenon gas, or a sputtering gas atmosphere consisting of 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 activated 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-based gas. Examples of hydrocarbon-based gases include methane gas, butane gas, propane gas, and styrene gas. By adjusting the sputtering voltage in the film-forming chamber during sputtering, the light-shielding film 3 can be formed into a columnar structure, similar to the semi-transparent film 2.

[0052] If the light-shielding film 3 is made of 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. If the light-shielding film 3 is made of multiple films 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. If the light-shielding film 3 is made of a single film whose composition 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 way, the mask blank 10A of the first embodiment is obtained.

[0053] When manufacturing a multi-tone mask blank having a light-shielding film 3 on a semi-transparent film 2 and a resist film on the light-shielding film 3, a resist film is formed on the light-shielding film 3 after the light-shielding film forming step.

[0054] The mask blank 10 of the first and second embodiments is a mask blank comprising a semi-transparent film 2 for forming a transfer pattern on a transparent substrate 1, the semi-transparent film 2 containing chromium, silicon, and nitrogen, the most abundant element being chromium, the silicon content of the semi-transparent film 2 being 2.8 atomic % or less, and the semi-transparent film 2 having a columnar structure. Therefore, a multi-tone mask blank can be obtained which can ensure sufficient adhesion between the semi-transparent film and a resist film when patterning the semi-transparent film by wet etching, and which can increase the in-plane CD of the semi-transparent pattern after patterning the semi-transparent film by wet etching.

[0055] Embodiment 3.4. Transfer masks 100A and 100B according to third and fourth embodiments and a method for manufacturing the same will be described (hereinafter, they may be simply referred to as "transfer mask 100").

[0056] Fig. 3 is a schematic diagram showing a transfer mask 100A according to a third embodiment. Fig. 4 is a schematic diagram showing a transfer mask 100B according to a fourth embodiment. The transfer mask 100A of the third embodiment has the same configuration as the mask blank 10A of the first embodiment, except that it has a semi-transparent pattern 2A in which a transfer pattern is formed on the semi-transparent film 2, and an etching stopper pattern 4A and a light-shielding pattern 3A in the etching stopper film 4 and the light-shielding film 3, which correspond to the light-shielding portion 13. When manufacturing the transfer mask 100A shown in Figure 3, a mask blank 10A is prepared in which a semi-transparent film 2, an etching stopper film 4, and a light-shielding film 3 are formed on the light-transmitting substrate 1 shown in Figure 1.

[0057] Next, a process for forming a light-shielding portion 13 having a predetermined pattern shape on the etching stopper film 4 and the light-shielding film 3 will be described. First, a first resist film is formed on the light-shielding film 3. There are no particular restrictions 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, which will be described later. The first resist film may be either positive or negative. Thereafter, a desired pattern corresponding to the light-shielding portion 13 is written on the first resist film using a laser beam having a wavelength selected from the wavelength range of 350 nm to 436 nm. Thereafter, the first resist film is developed with a predetermined developer to form a first resist pattern corresponding to the light-shielding portion 13 on the light-shielding film 3.

[0058] First, the light-shielding film 3 is etched using the first resist pattern as a mask to form a light-shielding pattern 3A. If the light-shielding film 3 has a columnar structure, this is preferable because the etching rate is fast and side etching can be suppressed. The etchant used to etch the light-shielding film 3 is not particularly limited as long as it can selectively etch the light-shielding film 3. Next, the etching stopper film 4 is etched using the first resist pattern and the light-shielding pattern 3A as masks to form an etching stopper pattern 4A. Thereafter, the first resist pattern is stripped using a resist stripper or by ashing.

[0059] In the second resist pattern forming step, first, a second resist film is formed to cover the semi-transparent film 2 and the light-shielding pattern 3A. Then, a desired pattern corresponding to the light-transmitting portion 11 is written on the second resist film using the above-mentioned laser light. Then, the second resist film is developed with a predetermined developer to form a second resist pattern having the pattern of the light-transmitting portion 11 on the semi-transparent film 2 and the light-shielding pattern 3A.

[0060] Then, the semi-transparent film 2 is wet-etched using the second resist pattern as a mask to form a semi-transparent pattern 2A as shown in Fig. 3. The etching solution used to etch the semi-transparent film 2 is not particularly limited as long as it can selectively etch the semi-transparent film 2. As described above, the semitransparent film 2 contains chromium, silicon, and nitrogen, with chromium being the most abundant element, the silicon content of the semitransparent film 2 being 2.8 atomic % or less, and the semitransparent film 2 having a columnar structure, which ensures sufficient adhesion between the semitransparent film 2 and the resist film (second resist pattern) during wet etching, and also enables the in-plane CD of the semitransparent pattern 2A to be increased after the semitransparent film 2 is patterned by wet etching.

[0061] Thereafter, the second resist pattern is stripped using a resist stripper or by ashing. In this manner, the transfer mask 100A shown in FIG. 3 can be manufactured.

[0062] The transfer mask 100B according to the fourth embodiment has the same configuration as the mask blank 10B according to the second embodiment, except that it is provided with a semi-transparent pattern 2B in which a transfer pattern is formed on a semi-transparent film 2. When manufacturing the transfer mask 100B shown in Fig. 4, the mask blank 10B shown in Fig. 2 is prepared. The mask blank 10B includes a light-transmitting substrate 1 and a semi-light-transmitting film 2 formed on the light-transmitting substrate 1, and includes a light-shielding pattern 3B between the light-transmitting substrate 1 and the semi-light-transmitting film 2.

[0063] Then, a resist film is formed on the semi-transparent film 2. After that, a desired pattern corresponding to the transparent portion 11 is drawn on the resist film using the above-mentioned laser light. Thereafter, the resist film is developed with a predetermined developer to form a resist pattern having a pattern of the light-transmitting portion 11 on the semi-transmitting film 2 . Then, using this resist pattern as a mask, the semi-transparent film 2 is wet-etched to form a semi-transparent pattern 2B so as to expose the translucent substrate 1 in the translucent portion 11. In this way, the translucent substrate 1 is exposed in the translucent portion 11, only the semi-transparent pattern 2B is formed on the translucent substrate 1 in the semi-transparent portion 12, and the light-shielding pattern 3B and the semi-transparent pattern 2B are stacked on the translucent substrate 1 in the light-shielding portion 13. As described above, the semi-transparent film 2 contains chromium, silicon, and nitrogen, with chromium being the most abundant element, the silicon content of the semi-transparent film 2 being 2.8 atomic % or less, and the semi-transparent film 2 having a columnar structure, which ensures sufficient adhesion between the semi-transparent film 2 and the resist film (resist pattern) during wet etching, and also enables the in-plane CD of the semi-transparent pattern to be increased after patterning the semi-transparent film by wet etching. In this manner, the transfer mask 100B shown in FIG. 4 can be manufactured.

[0064] According to the transfer masks 100A and 100B of these embodiments 3 and 4, it is possible to provide a transfer mask that can sufficiently ensure adhesion between the semi-transparent film and the resist film when patterning the semi-transparent film by wet etching, and that can increase the in-plane CD of the semi-transparent pattern after patterning the semi-transparent film by wet etching.

[0065] Embodiment 5 In the fifth embodiment, a method for manufacturing a display device will be described. The display device is manufactured by performing a step using the above-described transfer mask 100 (mask placement step) and a step of exposing and transferring a transfer pattern onto a resist film on the display device (exposure step). Each step will be described in detail below.

[0066] 1. Placement process In the placing step, the transfer mask 100 in the third and fourth embodiments is placed on a mask stage of an exposure tool. Here, the transfer mask 100 is positioned so as to face the resist film formed on the display device substrate via the projection optical system of the exposure tool.

[0067] 2.Pattern transfer process In the pattern transfer process, exposure light is irradiated onto the transfer mask 100 to transfer a semi-transparent pattern to a resist film formed on a display device substrate. The exposure light is composite light including light of multiple wavelengths selected from the wavelength range of 365 nm to 436 nm, or monochromatic light selected by cutting out 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 composite light including i-line, h-line, and g-line, or monochromatic i-line light. Using composite light as the exposure light allows the exposure light intensity to be increased and throughput to be improved, thereby reducing the manufacturing cost of the display device.

[0068] According to the method for manufacturing a display device of this fifth embodiment, it is possible to manufacture display devices with a high yield. [Example]

[0069] Example 1 To manufacture the mask blank of Example 1, first, a synthetic quartz glass substrate having a 1214 size (1220 mm×1400 mm) was prepared as a light-transmitting substrate 1 .

[0070] Thereafter, the synthetic quartz glass substrate was placed on a tray (not shown) with the main surface facing downward, and was then carried into the chamber of an in-line sputtering device. To form a semi-transparent film 2 on the main surface of the transparent substrate 1, an inert gas composed of argon (Ar) gas and nitrogen (N2) gas was introduced into the chamber. The deposition gas flow ratio (N2 / Ar) was 0.20. A sputtering voltage of 500 V was applied to a sputtering target containing chromium and silicon (chromium:silicon = 96:4), and a chromium silicide nitride containing chromium, silicon, and nitrogen was deposited on the main surface of the transparent substrate 1 by reactive sputtering. A semi-transparent film 2 with a thickness of 85 nm was then formed. After the semi-transparent film 2 was formed on the transparent substrate 1, it was removed from the chamber, and the surface of the semi-transparent film 2 was washed with pure water. In this manner, the mask blank 10 of Example 1 was produced.

[0071] Further, the semi-transparent film 2 of the mask blank 10 obtained under the film formation conditions of Example 1 was subjected to a depthwise composition analysis by X-ray photoelectron spectroscopy (XPS). The semi-transparent film 2 had a substantially constant content of each constituent element along the depth direction, except for the compositionally gradient region at the interface between the transparent substrate 1 and the semi-transparent film 2 and the surface region of the semi-transparent film 2, with carbon (C) at 1.3 atomic %, nitrogen (N) at 29.5 atomic %, oxygen (O) at 4.0 atomic %, silicon (Si) at 2.2 atomic %, and chromium (Cr) at 63.0 atomic %. Thus, Cr was the most abundant element, with Si at 2.8 atomic % or less. Furthermore, the ratio of silicon content to chromium content (Si / Cr) was 0.0349, or less than 0.035.

[0072] Next, cross-sectional SEM observation was performed at a magnification of 80,000 times at the center of the transfer pattern formation region of the obtained mask blank 10, and the results confirmed that the semi-transparent film 2 had a columnar structure. That is, it was confirmed that the particles containing chromium, silicon, and nitrogen that make up the semi-transparent film 2 have a columnar particle structure that extends in the film thickness direction of the semi-transparent film 2. It was also confirmed that the columnar particle structure of the semi-transparent film 2 is such that the columnar particles are irregularly formed in the film thickness direction, and the lengths of the columnar particles in the film thickness direction are also irregular. It was also confirmed that the sparse portions of the semi-transparent film 2 are continuously formed in the film thickness direction.

[0073] Furthermore, dark-field planar STEM observation was performed near the center of the film thickness of this semi-transparent film 2. As a result, it was confirmed that columnar particle portions and sparse portions were formed in the semi-transparent film 2.

[0074] Next, a photoresist film was applied so as to cover the semi-transparent film 2 using a resist coating device. Thereafter, a photoresist film was drawn using a laser drawing device, and after a development and rinsing process, a resist pattern was formed on the semi-transparent film 2 . Thereafter, using the resist pattern as a mask, the semi-transparent film 2 was wet-etched with a chrome etching solution containing ceric ammonium nitrate and perchloric acid to form a semi-transparent pattern 2A, thereby producing the transfer mask 100 of Example 1.

[0075] The cross section of the transfer mask with the resist pattern remaining was observed using a scanning electron microscope. Figure 5 is a cross-sectional photograph of the transfer mask of Example 1. As shown in the figure, the semi-transparent pattern of the transfer mask had a good cross-sectional shape that was nearly vertical. Furthermore, no penetration of the semi-transparent pattern was observed at either the interface with the resist pattern or the interface with the substrate, confirming that the semi-transparent pattern had good adhesion to the resist film. Furthermore, when the etching rate of the transfer mask of Example 1 was measured, it was found to be 2.57 nm / sec, which was within the range in which good CD control could be achieved.

[0076] Further, under the film-forming conditions of Example 1, a semi-transparent film 2 having a thickness of 23 nm was formed on the transparent substrate 1 on which a light-shielding pattern 3B made of chromium metal having a thickness of 110 nm was formed. The transmittance of the semi-transparent film of the obtained mask blank 10 was measured using an MPM-100 manufactured by Lasertec Corporation. To measure the transmittance of the semi-transparent film, a substrate with a semi-transparent film (dummy substrate) was used, which was prepared by setting it on the same tray and had a semi-transparent film 2 formed on the main surface of a synthetic quartz glass substrate. As a result, the transmittance was 9.9% (wavelength: 365 nm), which was 3% or more.

[0077] Then, a photoresist film was applied so as to cover the semi-transparent film 2 using a resist coating device. Thereafter, a photoresist film was drawn using a laser drawing device, and after a development and rinsing process, a resist pattern was formed on the semi-transparent film 2 . Thereafter, using the resist pattern as a mask, the semi-transparent film 2 was wet-etched with a chrome etching solution containing ceric ammonium nitrate and perchloric acid to form a semi-transparent pattern 2B, thereby producing the transfer mask 100B of Example 1.

[0078] The cross section of the resulting transfer mask was observed using a scanning electron microscope. The semi-transparent pattern 2B of the resulting transfer mask had a cross-sectional shape that was nearly vertical. The semi-transparent pattern 2B formed on the transfer mask of Example 1 had a cross-sectional shape that could fully function as a multi-tone mask. Furthermore, no penetration of the semi-transparent pattern 2B was observed at either the interface with the resist pattern or the interface with the substrate, confirming good adhesion to the resist film. Furthermore, when the CD of each pattern within the surface of the transfer mask was measured, it was confirmed that the pattern CD within the surface was highly uniform. From these results, it can be said that a transfer mask with excellent transfer performance was obtained. Furthermore, based on these results, it can be said that even when a transfer mask 100 having an etching stopper pattern 4A and a light-shielding pattern 3A on a semi-transparent pattern 2A is manufactured using a mask blank in which an etching stopper film 4 and a light-shielding film 3 are laminated on the mask blank 10 of Example 1, a transfer mask having a transfer pattern with good transfer accuracy can be obtained. Therefore, when the transfer mask of Example 1 is set on the mask stage of an exposure tool and exposed and transferred onto a resist film on a display device, the pattern can be transferred with high precision, and display devices can be manufactured with a high yield.

[0079] Example 2. To manufacture the mask blank of Example 2, similarly to Example 1, a synthetic quartz glass substrate having a 1214 size (1220 mm×1400 mm) was prepared as a light-transmitting substrate. Thereafter, the synthetic quartz glass substrate was placed on a tray (not shown) with the main surface facing downward, and was then carried into the chamber of an in-line sputtering device. To form a semi-transparent film 2 on the main surface of the transparent substrate 1, an inert gas composed of argon (Ar) gas and nitrogen (N2) gas was introduced into the chamber. The deposition gas flow ratio (N2 / Ar) was 0.30. A sputtering voltage of 500 V was applied to a sputtering target containing chromium and silicon (chromium:silicon = 96:4), and a chromium silicide nitride containing chromium, silicon, and nitrogen was deposited on the main surface of the transparent substrate 1 by reactive sputtering. A semi-transparent film 2 with a thickness of 99 nm was then formed. After the semi-transparent film 2 was formed on the transparent substrate 1, it was removed from the chamber, and the surface of the semi-transparent film 2 was washed with pure water. In this manner, the mask blank 10 of Example 2 was produced.

[0080] Furthermore, a composition analysis in the depth direction was performed by X-ray photoelectron spectroscopy (XPS) on the semi-transparent film 2 of the mask blank 10 obtained under the same film-forming conditions as in Example 2. The semi-transparent film 2 had a substantially constant content of each constituent element along the depth direction, except for the compositionally gradient region at the interface between the transparent substrate 1 and the semi-transparent film 2 and the surface region of the semi-transparent film 2, with C being 0.6 atomic %, N being 35.9 atomic %, O being 3.3 atomic %, Si being 1.8 atomic %, and Cr being 58.4 atomic %. Thus, Cr was the most abundant element, with Si being 2.8 atomic % or less. Furthermore, the ratio of silicon content to chromium content (Si / Cr) was 0.031, which was 0.035 or less.

[0081] Next, cross-sectional SEM observation was performed at a magnification of 80,000 times at the center of the transfer pattern formation region of the obtained mask blank 10, and the results confirmed that the semi-transparent film 2 had a columnar structure. That is, it was confirmed that the particles containing chromium, silicon, and nitrogen that make up the semi-transparent film 2 have a columnar particle structure that extends in the film thickness direction of the semi-transparent film 2. It was also confirmed that the columnar particle structure of the semi-transparent film 2 is such that the columnar particles are irregularly formed in the film thickness direction, and the lengths of the columnar particles in the film thickness direction are also irregular. It was also confirmed that the sparse portions of the semi-transparent film 2 are continuously formed in the film thickness direction.

[0082] Furthermore, dark-field planar STEM observation was performed near the center of the film thickness of this semi-transparent film 2. As a result, it was confirmed that columnar particle portions and sparse portions were formed in the semi-transparent film 2.

[0083] Next, a photoresist film was applied so as to cover the semi-transparent film 2 using a resist coating device. Thereafter, a photoresist film was drawn using a laser drawing device, and after a development and rinsing process, a resist pattern was formed on the semi-transparent film 2 . Thereafter, using the resist pattern as a mask, the semi-transparent film 2 was wet-etched with a chrome etching solution containing ceric ammonium nitrate and perchloric acid to form a semi-transparent pattern 2A, thereby producing the transfer mask 100 of Example 2.

[0084] The cross section of the resulting transfer mask was observed using a scanning electron microscope. Figure 6 is a cross-sectional photograph of the transfer mask of Example 2. As shown in the figure, the semi-transparent pattern of the transfer mask had a good cross-sectional shape that was nearly vertical. Furthermore, no penetration of the semi-transparent pattern was observed at either the interface with the resist pattern or the interface with the substrate, confirming that the semi-transparent pattern had good adhesion to the resist film. Furthermore, when the etching rate of the transfer mask of Example 2 was measured, it was found to be 4.94 nm / sec, which was within the range in which good CD control could be achieved.

[0085] Further, under the same film-forming conditions as in Example 2, a semi-transparent film 2 having a thickness of 16 nm was formed on the transparent substrate 1 on which a light-shielding pattern 3B made of chromium metal having a thickness of 110 nm was formed. The transmittance of the semi-transparent film of the obtained mask blank 10 was measured using an MPM-100 manufactured by Lasertec Corporation. To measure the transmittance of the semi-transparent film, a substrate with a semi-transparent film (dummy substrate) was used, which was prepared by setting it on the same tray and had a semi-transparent film 2 formed on the main surface of a synthetic quartz glass substrate. As a result, the transmittance was 20.3% (wavelength: 365 nm), which was 3% or more.

[0086] Then, a photoresist film was applied so as to cover the semi-transparent film 2 using a resist coating device. Thereafter, a photoresist film was drawn using a laser drawing device, and after a development and rinsing process, a resist pattern was formed on the semi-transparent film 2 . Thereafter, using the resist pattern as a mask, the semi-transparent film 2 was wet-etched with a chrome etching solution containing ceric ammonium nitrate and perchloric acid to form a semi-transparent pattern 2B, thereby producing a transfer mask 100B of Example 2.

[0087] The cross section of the resulting transfer mask was observed using a scanning electron microscope. The semi-transparent pattern 2B of the resulting transfer mask had a nearly vertical cross section. The semi-transparent pattern 2B formed on the transfer mask of Example 2 had a cross section that could fully function as a multi-tone mask. Furthermore, no penetration of the semi-transparent pattern 2B was observed at either the interface with the resist pattern or the interface with the substrate, confirming good adhesion to the resist film. Furthermore, CD measurements of each pattern within the surface of the transfer mask confirmed high uniformity of the pattern CD within the surface. From these results, it can be said that a transfer mask with excellent transfer performance was obtained. Furthermore, based on these results, it can be said that even when a transfer mask 100 having an etching stopper pattern 4A and a light-shielding pattern 3A on a semi-transparent pattern 2A is manufactured using a mask blank in which an etching stopper film 4 and a light-shielding film 3 are laminated on the mask blank 10 of Example 2, a transfer mask having a transfer pattern with good transfer accuracy can be obtained. Therefore, when the transfer mask of Example 2 is set on the mask stage of an exposure tool and exposed and transferred onto a resist film on a display device, the pattern can be transferred with high precision, and display devices can be manufactured with a high yield.

[0088] Example 3. To manufacture the mask blank of Example 3, similarly to Example 1, a synthetic quartz glass substrate having a 1214 size (1220 mm×1400 mm) was prepared as a light-transmitting substrate. Thereafter, the synthetic quartz glass substrate was placed on a tray (not shown) with the main surface facing downward, and was then carried into the chamber of an in-line sputtering device. To form a semi-transparent film 2 on the main surface of the transparent substrate 1, an inert gas composed of argon (Ar) gas and nitrogen (N2) gas was introduced into the chamber. The deposition gas flow ratio (N2 / Ar) was 0.66. A sputtering voltage of 500 V was applied to a sputtering target containing chromium and silicon (chromium:silicon = 96:4), and a chromium silicide nitride containing chromium, silicon, and nitrogen was deposited on the main surface of the transparent substrate 1 by reactive sputtering. A semi-transparent film 2 with a thickness of 57 nm was then formed. After the semi-transparent film 2 was formed on the transparent substrate 1, it was removed from the chamber, and the surface of the semi-transparent film 2 was washed with pure water. In this manner, the mask blank 10 of Example 3 was produced.

[0089] Furthermore, the semi-transparent film 2 of the mask blank 10 obtained under the same film-forming conditions as in Example 3 was subjected to depthwise composition analysis by X-ray photoelectron spectroscopy (XPS). The semi-transparent film 2 had a substantially constant content of each constituent element along the depth direction, except for the compositionally gradient region at the interface between the transparent substrate 1 and the semi-transparent film 2 and the surface region of the semi-transparent film 2, with C being 0.8 atomic %, N being 43.2 atomic %, O being 4.2 atomic %, Si being 1.5 atomic %, and Cr being 50.3 atomic %. Thus, Cr was the most abundant element, with Si being 2.8 atomic % or less. Furthermore, the ratio of silicon content to chromium content (Si / Cr) was 0.030, or less than 0.035.

[0090] Next, cross-sectional SEM observation was performed at a magnification of 80,000 times at the center of the transfer pattern formation region of the obtained mask blank 10, and the results confirmed that the semi-transparent film 2 had a columnar structure. That is, it was confirmed that the particles containing chromium, silicon, and nitrogen that make up the semi-transparent film 2 have a columnar particle structure that extends in the film thickness direction of the semi-transparent film 2. It was also confirmed that the columnar particle structure of the semi-transparent film 2 is such that the columnar particles are irregularly formed in the film thickness direction, and the lengths of the columnar particles in the film thickness direction are also irregular. It was also confirmed that the sparse portions of the semi-transparent film 2 are continuously formed in the film thickness direction.

[0091] Furthermore, dark-field planar STEM observation was performed near the center of the film thickness of this semi-transparent film 2. As a result, it was confirmed that columnar particle portions and sparse portions were formed in the semi-transparent film 2.

[0092] Next, a photoresist film was applied so as to cover the semi-transparent film 2 using a resist coating device. Thereafter, a photoresist film was drawn using a laser drawing device, and after a development and rinsing process, a resist pattern was formed on the semi-transparent film 2 . Then, using the resist pattern as a mask, the semi-transparent film 2 was wet-etched with a chrome etching solution containing ceric ammonium nitrate and perchloric acid to form a semi-transparent pattern 2A, thereby producing the transfer mask 100 of Example 3.

[0093] The cross section of the resulting transfer mask was observed using a scanning electron microscope. Figure 7 is a cross-sectional photograph of the transfer mask of Example 3. As shown in the figure, the semi-transparent pattern of the transfer mask had a favorable cross-sectional shape that was nearly vertical. Furthermore, no penetration was observed into the semi-transparent pattern at either the interface with the resist pattern or the interface with the substrate, confirming its favorable adhesion to the resist film. The etching rate of the transfer mask of Example 3 was measured and found to be 5.65 nm / sec, within the range in which favorable CD control could be achieved. Furthermore, under the same film formation conditions as in Example 3, a semi-transparent film 2 was formed on a transparent substrate 1 on which a light-shielding pattern 3B had been formed. The semi-transparent film 2 was then wet-etched to form a semi-transparent pattern 2B in the same manner as described in Examples 1 and 2, thereby producing a transfer mask 100B of Example 3. Measurement of the CD of each pattern within the surface of the transfer mask confirmed high uniformity of the pattern CD within the surface. These results suggest that a transfer mask with excellent transfer performance was obtained. Furthermore, based on these results, it can be said that even when a transfer mask 100 having an etching stopper pattern 4A and a light-shielding pattern 3A on a semi-transparent pattern 2A is manufactured using a mask blank in which an etching stopper film 4 and a light-shielding film 3 are laminated on the mask blank 10 of Example 3, a transfer mask having a transfer pattern with good transfer accuracy can be obtained.

[0094] Therefore, when the transfer mask of Example 3 is set on the mask stage of an exposure tool and exposed and transferred onto a resist film on a display device, the pattern can be transferred with high precision, and display devices can be manufactured with a high yield.

[0095] Example 4. To manufacture the mask blank of Example 4, similarly to Example 1, a synthetic quartz glass substrate having a 1214 size (1220 mm×1400 mm) was prepared as a light-transmitting substrate. Thereafter, the synthetic quartz glass substrate was placed on a tray (not shown) with the main surface facing downward, and was then carried into the chamber of an in-line sputtering device. To form a semi-transparent film 2 on the main surface of the transparent substrate 1, an inert gas composed of argon (Ar) gas was introduced into the chamber. The deposition gas flow ratio (N2 / Ar) was 0.01. A sputtering voltage of 485 V was applied to a sputtering target containing chromium and silicon (chromium:silicon = 96:4), and a chromium silicide nitride containing chromium, silicon, and nitrogen was deposited on the main surface of the transparent substrate 1 by reactive sputtering. A semi-transparent film 2 with a thickness of 79 nm was then formed. After the semi-transparent film 2 was formed on the transparent substrate 1, it was removed from the chamber, and the surface of the semi-transparent film 2 was washed with pure water. In this manner, the mask blank 10 of Example 4 was produced.

[0096] Furthermore, the semi-transparent film 2 of the mask blank 10 obtained under the same film-forming conditions as in Example 4 was subjected to a depthwise composition analysis using X-ray photoelectron spectroscopy (XPS). The semi-transparent film 2 had a substantially constant content of each constituent element along the depth direction, except for the compositionally gradient region at the interface between the transparent substrate 1 and the semi-transparent film 2 and the surface region of the semi-transparent film 2, with C being 0.8 atomic %, N being 0.7 atomic %, O being 8.9 atomic %, Si being 2.6 atomic %, and Cr being 87.0 atomic %. Thus, Cr was the most abundant element, with Si being 2.8 atomic % or less. Furthermore, the ratio of silicon content to chromium content (Si / Cr) was 0.030, or less than 0.035.

[0097] Next, cross-sectional SEM observation was performed at a magnification of 80,000 times at the center of the transfer pattern formation region of the obtained mask blank 10, and the results confirmed that the semi-transparent film 2 had a columnar structure. That is, it was confirmed that the particles containing chromium, silicon, and nitrogen that make up the semi-transparent film 2 have a columnar particle structure that extends in the film thickness direction of the semi-transparent film 2. It was also confirmed that the columnar particle structure of the semi-transparent film 2 is such that the columnar particles are irregularly formed in the film thickness direction, and the lengths of the columnar particles in the film thickness direction are also irregular. It was also confirmed that the sparse portions of the semi-transparent film 2 are continuously formed in the film thickness direction.

[0098] Furthermore, dark-field planar STEM observation was performed near the center of the film thickness of this semi-transparent film 2. As a result, it was confirmed that columnar particle portions and sparse portions were formed in the semi-transparent film 2.

[0099] Next, a photoresist film was applied so as to cover the semi-transparent film 2 using a resist coating device. Thereafter, a photoresist film was drawn using a laser drawing device, and after a development and rinsing process, a resist pattern was formed on the semi-transparent film 2 . Then, using the resist pattern as a mask, the semi-transparent film 2 was wet-etched with a chrome etching solution containing ceric ammonium nitrate and perchloric acid to form a semi-transparent pattern 2A, thereby producing the transfer mask 100 of Example 4.

[0100] The cross section of the resulting transfer mask was observed using a scanning electron microscope. Figure 8 is a cross-sectional photograph of the transfer mask of Example 4. As shown in the figure, the semi-transparent pattern of the transfer mask had a favorable cross-sectional shape that was nearly vertical. Furthermore, no penetration of the semi-transparent pattern was observed at either the interface with the resist pattern or the interface with the substrate, confirming its favorable adhesion to the resist film. The etching rate of the transfer mask of Example 4 was measured and found to be 1.71 nm / sec, within the range in which favorable CD control could be achieved. Furthermore, under the same film formation conditions as in Example 4, a semi-transparent film 2 was formed on a transparent substrate 1 on which a light-shielding pattern 3B had been formed. The semi-transparent film 2 was then wet-etched to form a semi-transparent pattern 2B in the same manner as described in Examples 1 and 2, thereby producing a transfer mask 100B of Example 4. Measurement of the CD of each pattern within the surface of the transfer mask confirmed high uniformity of the pattern CD within the surface. These results suggest that a transfer mask with excellent transfer performance was obtained. Furthermore, based on these results, it can be said that even when a transfer mask 100 having an etching stopper pattern 4A and a light-shielding pattern 3A on a semi-transparent pattern 2A is manufactured using a mask blank in which an etching stopper film 4 and a light-shielding film 3 are laminated on the mask blank 10 of Example 4, a transfer mask having a transfer pattern with good transfer accuracy can be obtained.

[0101] Therefore, when the transfer mask of Example 4 is set on the mask stage of an exposure tool and exposed and transferred onto a resist film on a display device, the pattern can be transferred with high precision, and display devices can be manufactured with a high yield.

[0102] In the above-described embodiments, examples of a multi-tone mask blank for manufacturing a display device and a transfer mask for manufacturing a display device have been described, but the present invention is not limited to these. The mask blank and transfer mask of the present invention can also be applied to semiconductor device manufacturing, MEMS manufacturing, printed circuit board manufacturing, etc. The present invention can also be applied to a binary mask blank having a light-shielding film as a pattern-forming thin film and a binary mask having a light-shielding pattern. In the above-described embodiment, the size of the light-transmitting substrate is 1214 size (1220 mm × 1400 mm × 13 mm), but the size is not limited to this. In the case of a multi-tone mask blank for manufacturing a display device, a large-size light-transmitting substrate is used, and the size of the light-transmitting substrate is 300 mm or more on one side. The size of the light-transmitting substrate used in a multi-tone mask blank for manufacturing a display device is, for example, 330 mm × 450 mm or more and 2280 mm × 3130 mm or less. Furthermore, in the case of multi-tone mask blanks for semiconductor device manufacturing, MEMS manufacturing, and printed circuit boards, small-sized light-transmitting substrates are used, and the size of the light-transmitting substrate has a side length of 9 inches or less. The size of the light-transmitting substrate used in multi-tone mask blanks for the above uses is, for example, 63.1 mm × 63.1 mm or more and 228.6 mm × 228.6 mm or less. Typically, 6025 size (152 mm × 152 mm) or 5009 size (126.6 mm × 126.6 mm) is used for semiconductor manufacturing and MEMS manufacturing, while 7012 size (177.4 mm × 177.4 mm) or 9012 size (228.6 mm × 228.6 mm) is used for printed circuit boards.

[0103] Comparative Example 1 To manufacture the mask blank of Comparative Example 1, similarly to Example 1, a synthetic quartz glass substrate having a 1214 size (1220 mm×1400 mm) was prepared as a light-transmitting substrate. Thereafter, the synthetic quartz glass substrate was placed on a tray (not shown) with the main surface facing downward, and was then carried into the chamber of an in-line sputtering device. To form a semi-transparent film 2 on the main surface of the transparent substrate 1, an inert gas composed of argon (Ar) gas and nitrogen (N2) gas was introduced into the chamber. The deposition gas flow ratio (N2 / Ar) was 0.54. A sputtering voltage of 550 V was applied to a sputtering target containing chromium and silicon (chromium:silicon = 96:4), and a chromium silicide nitride containing chromium, silicon, and nitrogen was deposited on the main surface of the transparent substrate 1 by reactive sputtering. A semi-transparent film 2 with a thickness of 81 nm was then formed. After the semi-transparent film 2 was formed on the transparent substrate 1, it was removed from the chamber, and the surface of the semi-transparent film 2 was washed with pure water. In this manner, the mask blank 10 of Comparative Example 1 was produced.

[0104] Furthermore, a depthwise composition analysis was performed by X-ray photoelectron spectroscopy (XPS) on the semi-transparent film 2 of the mask blank 10 obtained under the same film-forming conditions as in Comparative Example 1. Except for the gradient composition region at the interface between the transparent substrate 1 and the semi-transparent film 2 and the surface region of the semi-transparent film 2, the content of each constituent element in the semi-transparent film 2 was almost constant along the depthwise direction, with C being 0.6 atomic %, N being 31.5 atomic %, O being 0.6 atomic %, Si being 2.6 atomic %, and Cr being 64.7 atomic %. Thus, Cr was the most abundant element, with Si being 2.8 atomic % or less. Meanwhile, the ratio of silicon content to chromium content (Si / Cr) was 0.040, not less than 0.035.

[0105] Next, cross-sectional SEM observation was performed at a magnification of 80,000 times at the center of the transfer pattern formation area of ​​the obtained mask blank 10. As a result, no columnar structure was observed in the semi-transparent film, and it was confirmed that it had an ultrafine crystalline structure or amorphous structure.

[0106] Next, a photoresist film was applied so as to cover the semi-transparent film 2 using a resist coating device. Thereafter, a photoresist film was drawn using a laser drawing device, and after a development and rinsing process, a resist pattern was formed on the semi-transparent film 2 . Thereafter, using the resist pattern as a mask, the semi-transparent film 2 was wet-etched with a chrome etching solution containing ceric ammonium nitrate and perchloric acid to form a semi-transparent pattern 2A, thereby producing the transfer mask 100 of Comparative Example 1.

[0107] The cross section of the resulting transfer mask was observed using a scanning electron microscope. Figure 9 is a cross-sectional photograph of the transfer mask of Comparative Example 1. As shown in the figure, the semi-transparent pattern of the transfer mask was found to have infiltrated into the interface with the resist pattern, and the cross-sectional shape was significantly deteriorated. The etching rate of the transfer mask of Comparative Example 1 was measured and found to be 5.41 nm / sec.

[0108] Therefore, when the transfer mask of Comparative Example 1 is set on the mask stage of an exposure tool and exposed and transferred onto a resist film on a display device, it is expected that the pattern cannot be transferred.

[0109] Comparative Example 2 To manufacture the mask blank of Comparative Example 2, similarly to Example 1, a synthetic quartz glass substrate having a 1214 size (1220 mm×1400 mm) was prepared as a light-transmitting substrate. Thereafter, the synthetic quartz glass substrate was placed on a tray (not shown) with the main surface facing downward, and was then carried into the chamber of an in-line sputtering device. To form a semi-transparent film 2 on the main surface of the transparent substrate 1, an inert gas composed of argon (Ar) gas and nitrogen (N2) gas was introduced into the chamber. The deposition gas flow ratio (N2 / Ar) was 0.66. A sputtering voltage of 550 V was applied to a sputtering target containing chromium and silicon (chromium:silicon = 96:4), and a chromium silicide nitride containing chromium, silicon, and nitrogen was deposited on the main surface of the transparent substrate 1 by reactive sputtering. A semi-transparent film 2 with a thickness of 80 nm was then formed. After the semi-transparent film 2 was formed on the transparent substrate 1, it was removed from the chamber, and the surface of the semi-transparent film 2 was washed with pure water. In this manner, the mask blank 10 of Comparative Example 2 was produced.

[0110] Furthermore, a composition analysis in the depth direction was performed by X-ray photoelectron spectroscopy (XPS) on the semi-transparent film 2 of the mask blank 10 obtained under the same film-forming conditions as those of Comparative Example 2. The semi-transparent film 2 had a substantially constant content of each constituent element along the depth direction, except for the compositionally gradient region at the interface between the transparent substrate 1 and the semi-transparent film 2 and the surface region of the semi-transparent film 2, with C being 0.1 atomic %, N being 34.2 atomic %, O being 0.3 atomic %, Si being 2.4 atomic %, and Cr being 63.0 atomic %. Thus, Cr was the most abundant element, with Si being 2.8 atomic % or less. Meanwhile, the ratio of silicon content to chromium content (Si / Cr) was 0.038, not less than 0.035.

[0111] Next, cross-sectional SEM observation was performed at a magnification of 80,000 times at the center of the transfer pattern formation area of ​​the obtained mask blank 10. As a result, no columnar structure was observed in the semi-transparent film, and it was confirmed that it had an ultrafine crystalline structure or amorphous structure.

[0112] Next, a photoresist film was applied so as to cover the semi-transparent film 2 using a resist coating device. Thereafter, a photoresist film was drawn using a laser drawing device, and after a development and rinsing process, a resist pattern was formed on the semi-transparent film 2 . Thereafter, using the resist pattern as a mask, the semi-transparent film 2 was wet-etched with a chrome etching solution containing ceric ammonium nitrate and perchloric acid to form a semi-transparent pattern 2A, thereby producing a transfer mask 100 of Comparative Example 2.

[0113] The cross section of the resulting transfer mask was observed using a scanning electron microscope. Figure 10 is a cross-sectional photograph of the transfer mask of Comparative Example 2. As shown in the figure, the semi-transparent pattern of the transfer mask was found to have infiltrated into the interface with the resist pattern, and the cross-sectional shape was significantly deteriorated. The etching rate of the transfer mask of Comparative Example 2 was measured and found to be 6.15 nm / sec.

[0114] For this reason, when the transfer mask of Comparative Example 2 is set on the mask stage of an exposure tool and exposed and transferred onto a resist film on a display device, it is expected that the pattern cannot be transferred.

[0115] Comparative Example 3. To manufacture the mask blank of Comparative Example 3, similarly to Example 1, a synthetic quartz glass substrate having a 1214 size (1220 mm×1400 mm) was prepared as a light-transmitting substrate. Thereafter, the synthetic quartz glass substrate was placed on a tray (not shown) with the main surface facing downward, and was then carried into the chamber of an in-line sputtering device. To form a semi-transparent film 2 on the main surface of the transparent substrate 1, an inert gas composed of argon (Ar) gas and nitrogen (N2) gas was introduced into the chamber. The deposition gas flow ratio (N2 / Ar) was 0.60. A sputtering voltage of 485 V was applied to a sputtering target composed of chromium, and chromium nitride containing chromium and nitrogen was deposited on the main surface of the transparent substrate 1 by reactive sputtering. A semi-transparent film 2 having a thickness of 23 nm was then formed. After the semi-transparent film 2 was formed on the transparent substrate 1, it was removed from the chamber, and the surface of the semi-transparent film 2 was washed with pure water. In this manner, a mask blank 10 of Comparative Example 3 was produced.

[0116] Furthermore, a composition analysis in the depth direction was performed by X-ray photoelectron spectroscopy (XPS) on the semi-transparent film 2 of the mask blank 10 obtained under the same film-forming conditions as in Comparative Example 3. The semi-transparent film 2 had an almost constant content of each constituent element in the depth direction, except for the compositionally gradient region at the interface between the transparent substrate 1 and the semi-transparent film 2 and the surface region of the semi-transparent film 2, with C being 0.7 atomic %, N being 45.8 atomic %, O being 0.8 atomic %, Si being 0.0 atomic %, and Cr being 52.7 atomic %. Thus, Cr was the element with the highest content, and Si was not present.

[0117] Next, a cross section of the mask blank 10 was observed at the center of the transfer pattern formation region at a magnification of 80,000 times using an SEM, and it was confirmed that the semi-transparent film 2 had a columnar structure.

[0118] The transmittance of the semi-transparent film of the obtained mask blank 10 was measured using an MPM-100 manufactured by Lasertec Corporation. To measure the transmittance of the semi-transparent film, a substrate with a semi-transparent film (dummy substrate) was used, which was prepared by setting it on the same tray and had a semi-transparent film 2 formed on the main surface of a synthetic quartz glass substrate. As a result, the transmittance was 14.1% (wavelength: 365 nm).

[0119] Next, a photoresist film was applied so as to cover the semi-transparent film 2 using a resist coating device. Thereafter, a photoresist film was drawn using a laser drawing device, and after a development and rinsing process, a resist pattern was formed on the semi-transparent film 2 . Thereafter, using the resist pattern as a mask, the semi-transparent film 2 was wet-etched with a chrome etching solution containing ceric ammonium nitrate and perchloric acid to form a semi-transparent pattern 2A, thereby producing a transfer mask 100 of Comparative Example 3.

[0120] 11 is a graph showing the relationship between the nitrogen content and the etching rate for Examples 1 to 3 and Comparative Example 3. As shown in the figure, when the etching rate of the transfer mask of Comparative Example 3 was measured, it was 7.48 nm / sec, which was significantly higher than the etching rates in Examples 1 to 3 and was outside the range in which good CD control could be achieved. When the transfer mask of Comparative Example 3 was observed with a scanning electron microscope, it was confirmed that the CD was significantly reduced in areas where the pattern was relatively sparse.

[0121] Therefore, when the transfer mask of Comparative Example 3 is set on the mask stage of an exposure tool and exposed and transferred onto a resist film on a display device, it is expected that the pattern cannot be transferred with high precision. [Explanation of symbols]

[0122] 1 Translucent substrate 2 Semi-transparent film 3. Light-shielding film 2A, 2B Semi-transparent pattern (semi-transparent film with transfer pattern formed) 3A, 3B Light blocking pattern 10(10A, 10B) Mask Blank 11 Translucent part 12 Semi-transparent part 13 Light blocking section 100 (100A, 100B) Transfer mask

Claims

1. A mask blank comprising a thin film for forming a transfer pattern on a light-transmitting substrate, the thin film contains chromium, silicon, and nitrogen; the element most abundant in the thin film is chromium; the silicon content of the thin film is 2.8 atomic % or less; The thin film has a columnar structure A mask blank characterized by:

2. 2. The mask blank according to claim 1, wherein the ratio of the silicon content to the chromium content in said thin film is 0.035 or less.

3. 2. The mask blank according to claim 1, wherein the chromium content in said thin film is 50 atomic % or more.

4. 2. The mask blank according to claim 1, wherein the nitrogen content in said thin film is 25 atomic % or more.

5. 2. The mask blank according to claim 1, wherein the total content of chromium, silicon, and nitrogen in said thin film is 90 atomic % or more.

6. 2. The mask blank according to claim 1, wherein the columnar structure of the thin film is a structure in which columnar particles extending in a film thickness direction are formed across the surface of the light-transmitting substrate.

7. 7. The mask blank according to claim 6, wherein the thin film has portions where the columnar particles have a relatively high density and portions where the density is relatively low and sparse.

8. 2. The mask blank according to claim 1, wherein the thin film has a transmittance of 3% or more for light with a wavelength of 365 nm.

9. A mask blank comprising a thin film on which a transfer pattern is formed on a light-transmitting substrate, the thin film contains chromium, silicon, and nitrogen; the element most abundant in the thin film is chromium; the silicon content of the thin film is 2.8 atomic % or less; The thin film has a columnar structure A transfer mask characterized by:

10. 10. The transfer mask according to claim 9, wherein the ratio of the silicon content to the chromium content in said thin film is 0.035 or less.

11. 10. The transfer mask according to claim 9, wherein the chromium content in said thin film is 50 atomic % or more.

12. 10. The transfer mask according to claim 9, wherein the nitrogen content in said thin film is 25 atomic % or more.

13. 10. The transfer mask according to claim 9, wherein the total content of chromium, silicon, and nitrogen in said thin film is 90 atomic % or more.

14. 10. The transfer mask according to claim 9, wherein the columnar structure of the thin film is a structure in which columnar particles extending in a film thickness direction are formed across the surface of the light-transmitting substrate.

15. 15. The transfer mask according to claim 14, wherein the thin film has portions where the columnar particles have a relatively high density and portions where the density is relatively low.

16. 10. The transfer mask according to claim 9, wherein the thin film has a transmittance of 3% or more for light with a wavelength of 365 nm.

17. 17. A method for manufacturing a display device, comprising an exposure step of placing the transfer mask according to claim 9 on a mask stage of an exposure device, and exposing and transferring the transfer pattern formed on the transfer mask to a resist formed on a display device substrate.

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