JP2024089845A - Mask blank, transfer mask, method for manufacturing a transfer mask, and method for manufacturing a display device - Google Patents

Abstract

[Problem] To provide a mask blank that satisfies the requirement of high light resistance against exposure light including wavelengths in the ultraviolet region. [Solution] A mask blank comprising a thin film for pattern formation on a light-transmitting substrate, the thin film containing a transition metal and silicon, and an X-ray absorption spectrum of the surface layer of the thin film obtained by a total electron yield method, where IL is the X-ray absorption coefficient at an incident X-ray energy EL of 3180 eV, and IH is the X-ray absorption coefficient at an incident X-ray energy EH of 3210 eV, is such that (IH-IL)/(EH-EL) is -6.0×10-4 or more. [Selected Figure] Figure 6

Description

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

In recent years, display devices such as FPDs (Flat Panel Displays) typified by OLEDs (Organic Light Emitting Diodes) have been rapidly increasing in size, viewing angle, flexibility (folding, etc.), high definition, and display speed. One of the elements required for this high definition and high speed display is the creation of electronic circuit patterns such as fine elements and wiring with high dimensional accuracy. Photolithography is often used for patterning the electronic circuits for these display devices. For this reason, transfer masks (photomasks) such as phase shift masks and binary masks, which have fine and high-precision patterns, are required for the manufacture of display devices.

For example, Patent Document 1 describes a photomask for exposing a fine pattern. Patent Document 1 describes that the mask pattern formed on the transparent substrate of the photomask is composed of a light-transmitting portion that transmits light of an intensity that substantially contributes to exposure, and a light-semi-transmitting portion that transmits light of an intensity that does not substantially contribute to exposure. Patent Document 1 also describes that the phase shift effect is used to improve the contrast of the boundary portion by making the light that passes near the boundary portion between the light-semi-transmitting portion and the light-transmitting portion cancel each other out. Patent Document 1 also describes that the photomask comprises a light-semi-transmitting portion made of a thin film made of a material whose main components are nitrogen, metal, and silicon, and that the thin film contains 34 to 60 atomic % silicon, which is a component of the material that makes up the thin film.

Patent Document 2 describes a half-tone phase-shift mask blank for use in lithography. Patent Document 2 describes that the mask blank comprises a substrate, an etch stop layer deposited on the substrate, and a phase-shift layer deposited on the etch stop layer. Patent Document 2 further describes that the mask blank can be used to manufacture a photomask having a phase shift of approximately 180 degrees at a selected wavelength less than 500 nm and an optical transmittance of at least 0.001%.

Japanese Patent No. 2966369 JP 2005-522740 A

In recent years, the transfer masks used in the production of high-definition (1000 ppi or more) panels require a transfer mask on which a transfer pattern is formed that includes a thin film pattern for forming a fine pattern with a hole diameter of 6 μm or less and a line width of 4 μm or less in order to enable high-resolution pattern transfer. Specifically, there is a demand for a transfer mask on which a transfer pattern is formed that includes a fine pattern with a diameter or width dimension of 1.5 μm.

On the other hand, the transfer mask obtained by patterning the thin film for pattern formation of the mask blank is used repeatedly to transfer patterns to the transfer target, so it is desirable that the transfer mask also has high resistance to ultraviolet light (ultraviolet light resistance) in anticipation of actual pattern transfer.

However, it has been difficult to manufacture mask blanks equipped with a thin film for pattern formation that meets the requirements for ultraviolet resistance (hereinafter simply referred to as light resistance) against exposure light that includes wavelengths in the ultraviolet region.

The present invention has been made to solve the above-mentioned problems. That is, the object of the present invention is to provide a mask blank that meets the requirement of high light resistance against exposure light including wavelengths in the ultraviolet region.

The present invention also aims to provide a transfer mask having a good transfer pattern that meets the requirement of high light resistance to exposure light including wavelengths in the ultraviolet region, a method for manufacturing the transfer mask, and a method for manufacturing a display device.

The present invention has the following configuration as a means for solving the above problems.

(Configuration 1) A mask blank comprising a thin film for pattern formation on a light-transmitting substrate,
the thin film contains a transition metal and silicon;
The X-ray absorption spectrum of the surface layer of the thin film obtained by the total electron yield method is
IL is the X-ray absorption coefficient when the incident X-ray energy EL is 3180 eV,
When the X-ray absorption coefficient at the incident X-ray energy EH of 3210 eV is IH,
A mask blank, characterized in that (IH-IL)/(EH-EL) is -6.0×10 ^-4 or more.

(Configuration 2) A mask blank according to configuration 1, characterized in that the X-ray absorption spectrum of the thin film obtained by a fluorescence yield method has a larger X-ray absorption coefficient at an incident X-ray energy EH of 3210 eV than at an incident X-ray energy EL of 3180 eV.

(Configuration 3) The mask blank according to configuration 1, characterized in that the thin film contains at least titanium as the transition metal.

(Configuration 4) The mask blank according to configuration 1, characterized in that the thin film further contains nitrogen.

(Configuration 5) A mask blank according to configuration 1, characterized in that the ratio of the transition metal content to the total content of the transition metal and silicon in the thin film is 0.05 or more.

(Configuration 6) A mask blank according to configuration 1, characterized in that an etching mask film having a different etching selectivity with respect to the thin film is provided on the thin film.

(Configuration 7) The mask blank according to configuration 6, characterized in that the etching mask film contains chromium.

(Configuration 8) A transfer mask comprising a thin film having a transfer pattern on a light-transmitting substrate,
the thin film contains a transition metal and silicon;
The X-ray absorption spectrum of the surface layer of the thin film obtained by the total electron yield method is
IL is the X-ray absorption coefficient when the incident X-ray energy EL is 3180 eV,
When the X-ray absorption coefficient at the incident X-ray energy EH of 3210 eV is IH,
A transfer mask, wherein (IH-IL)/(EH-EL) is -6.0×10 ^-4 or more.

(Configuration 9) A transfer mask according to configuration 8, characterized in that the X-ray absorption spectrum of the thin film obtained by the fluorescence yield method has a larger X-ray absorption coefficient at an incident X-ray energy EH of 3210 eV than at an incident X-ray energy EL of 3180 eV.

(Configuration 10) The transfer mask according to configuration 8, characterized in that the thin film contains at least titanium as the transition metal.

(Configuration 11) The transfer mask according to configuration 8, characterized in that the thin film further contains nitrogen.

(Configuration 12) A transfer mask according to configuration 8, characterized in that the ratio of the transition metal content to the total content of the transition metal and silicon in the thin film is 0.05 or more.

(Configuration 13) A process for preparing a mask blank according to configuration 6 or 7;
forming a resist film having a transfer pattern on the etching mask film;
performing wet etching using the resist film as a mask to form a transfer pattern on the etching mask film;
performing wet etching using the etching mask film on which the transfer pattern is formed as a mask to form a transfer pattern on the thin film;
2. A method for producing a transfer mask comprising the steps of:

(Configuration 14) A step of placing the transfer mask according to any one of configurations 8 to 12 on a mask stage of an exposure tool;
a step of irradiating the transfer mask with exposure light to transfer a transfer pattern onto a resist film provided on a substrate for a display device;
A method for manufacturing a display device comprising the steps of:

The present invention can provide a mask blank that meets the requirement of high light resistance to exposure light including wavelengths in the ultraviolet region.

The present invention also provides a transfer mask having a good transfer pattern that meets the requirement of high light resistance to exposure light including wavelengths in the ultraviolet region, a method for manufacturing the transfer mask, and a method for manufacturing a display device.

FIG. 2 is a cross-sectional schematic diagram showing a film configuration of a mask blank according to an embodiment of the present invention. FIG. 2 is a schematic cross-sectional view showing another film configuration of a mask blank according to an embodiment of the present invention. 3A to 3C are schematic cross-sectional views showing a manufacturing process of a transfer mask according to an embodiment of the present invention. 10A to 10C are schematic cross-sectional views showing another manufacturing process of the transfer mask according to the embodiment of the present invention. FIG. 1 shows X-ray absorption spectra (horizontal axis: X-ray energy incident on the thin film, vertical axis: X-ray absorption coefficient of the thin film for that X-ray energy) derived from Ar obtained by a fluorescence yield method for the thin films for pattern formation of the mask blanks according to Examples 1 to 3 and Comparative Examples 1 and 2 of the present invention. FIG. 1 shows X-ray absorption spectra (horizontal axis: X-ray energy incident on the surface layer of the thin film, vertical axis: X-ray absorption coefficient of the surface layer of the thin film for X-rays of that energy) derived from Ar obtained by a total electron yield method for the surface layer of the thin film for pattern formation of the mask blanks according to Examples 1 to 3 and Comparative Examples 1 and 2 of the present invention. 1 is a diagram showing the relationship between (IH-IL)/(EH-EL) and the change in transmittance in a thin film for pattern formation of a mask blank according to Examples 1 to 3 of the present invention and Comparative Examples 1 and 2. Here, IL is the X-ray absorption coefficient when the incident X-ray energy EL is 3180 eV, and IH is the X-ray absorption coefficient when the incident X-ray energy EH is 3210 eV.

First, the background to the completion of the present invention will be described. The present inventors have conducted extensive research into the configuration of a mask blank that satisfies the requirement for high light resistance to exposure light having a wavelength in the ultraviolet region (hereinafter, may be simply referred to as "exposure light").
The present inventor has been considering using a transition metal silicide-based material containing a transition metal and silicon as a material for a thin film pattern of a transfer mask used for manufacturing a display device such as an FPD (Flat Panel Display). It has been found that in a thin film formed using a transition metal silicide-based material, although the composition is almost the same, a large difference in light resistance to exposure light may occur. For this reason, the present inventor has conducted a multifaceted verification of the difference between a thin film of a transition metal silicide-based material having high light resistance to exposure light and a thin film of a transition metal silicide-based material having low light resistance to exposure light. First, the present inventor has examined the relationship between the composition of the thin film and the light resistance to exposure light, but no clear correlation has been obtained between the composition of the thin film and the light resistance. In addition, cross-sectional SEM images, planar STEM images, and electron diffraction images have been observed, but no clear correlation has been obtained between any of them and light resistance.

The inventors therefore focused on the gas components used when forming the thin film. When forming a thin film of a transition metal silicide material on a light-transmitting substrate, the sputtering method is generally used. When forming a thin film of a transition metal silicide material by sputtering, a noble gas is generally flowed into the film formation chamber in addition to a reactive gas. This is because the sputtering efficiency can be increased by turning the noble gas into plasma and colliding it with the target. In addition, argon is widely used as the noble gas. It is believed that the thin film formed in this way contains noble gas components, although in very small amounts.

Based on this perspective, we used the fluorescence yield method to obtain and analyze X-ray absorption spectra derived from Ar for thin films of transition metal silicide materials that differ greatly in light resistance to exposure light (see Figure 5). As a result, we were able to confirm that argon derived from the sputtering gas was incorporated into each thin film, but no clear correlation was found with light resistance.

As a result of further intensive research, the inventors obtained and analyzed X-ray absorption spectra (horizontal axis: X-ray energy incident on the surface layer of the thin film, vertical axis: X-ray absorption coefficient of the surface layer of the thin film for X-rays of that energy) derived from Ar by the total electron yield method for the surface layer of a transition metal silicide-based material, which has a significantly different light resistance to exposure light including wavelengths in the ultraviolet region (see Figures 6 and 7). The X-ray absorption spectrum of a thin film obtained by the fluorescence yield method has a sufficiently deep range in the film thickness direction, and a spectrum reflecting the entire state of the thin film in the film thickness direction (surface layer + other regions) is obtained. The spectrum contains information related to the state of the surface layer of the thin film and other regions, and it is difficult to separate the state of the surface layer of the thin film from the state of the other regions. In contrast, the X-ray absorption spectrum of a thin film obtained by the total electron yield method has a very shallow range in the film thickness direction, and the spectrum reflects the state of the surface layer of the thin film to a large extent. When the X-ray absorption spectra obtained by the total electron yield method were analyzed for thin films with significantly different light resistance, it was found that there was a clear difference in the trends of the X-ray absorption coefficients between the two.

The mask blank of the present invention has been arrived at as a result of the above-mentioned intensive research. That is, the mask blank comprises a thin film for pattern formation on a light-transmitting substrate, the thin film containing a transition metal and silicon, and the X-ray absorption spectrum of the surface layer of the thin film obtained by a total electron yield method is expressed as follows, where IL is the X-ray absorption coefficient at an incident X-ray energy EL of 3180 eV and IH is the X-ray absorption coefficient at an incident X-ray energy EH of 3210 eV:
It is characterized in that (IH-IL)/(EH-EL) is -6.0×10 ^-4 or more.
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that the following embodiments are forms for embodying the present invention, and are not intended to limit the scope of the present invention.

Figure 1 is a schematic diagram showing the film configuration of a mask blank 10 of this embodiment. The mask blank 10 shown in Figure 1 includes a light-transmitting substrate 20, a thin film 30 for pattern formation (e.g., a phase shift film) formed on the light-transmitting substrate 20, and an etching mask film (e.g., a light-shielding film) 40 formed on the thin film 30 for pattern formation.

Figure 2 is a schematic diagram showing the film configuration of a mask blank 10 of another embodiment. The mask blank 10 shown in Figure 2 comprises a light-transmitting substrate 20 and a thin film 30 for pattern formation (e.g., a phase shift film) formed on the light-transmitting substrate 20.

In this specification, the term "thin film 30 for pattern formation" refers to a thin film on which a predetermined fine pattern is formed in the transfer mask 100, such as a light-shielding film and a phase-shifting film (hereinafter, sometimes simply referred to as "thin film 30"). In the description of this embodiment, a phase-shifting film may be used as an example of a specific example of the thin film 30 for pattern formation, and a phase-shifting film pattern may be used as an example of a specific example of the thin film pattern 30a for pattern formation (hereinafter, sometimes simply referred to as "thin film pattern 30a"). The same applies to the phase-shifting film and phase-shifting film pattern in other thin films 30 for pattern formation and thin film patterns 30a for pattern formation, such as light-shielding films and light-shielding film patterns, transmittance adjustment films and transmittance adjustment film patterns.

The following is a detailed description of the light-transmitting substrate 20, the thin film 30 for pattern formation (e.g., a phase shift film), and the etching mask film 40 that constitute the mask blank 10 for manufacturing a display device according to this embodiment.

<Light-transmitting substrate 20>
The light-transmitting substrate 20 is transparent to the exposure light. The light-transmitting substrate 20 has a transmittance of 85% or more, preferably 90% or more, to the exposure light when there is no surface reflection loss. The light-transmitting substrate 20 is made of a material containing silicon and oxygen, and can be made of glass materials such as synthetic quartz glass, quartz glass, aluminosilicate glass, soda lime glass, and low thermal expansion glass (SiO ₂ -TiO ₂ glass, etc.). When the light-transmitting substrate 20 is made of low thermal expansion glass, the position change of the thin film pattern 30a caused by thermal deformation of the light-transmitting substrate 20 can be suppressed. In addition, the light-transmitting substrate 20 used for display device applications is generally a rectangular substrate. Specifically, a light-transmitting substrate 20 having a short side length of 300 mm or more on the main surface (the surface on which the thin film 30 for pattern formation is formed) can be used. In the mask blank 10 of this embodiment, a large-sized light-transmitting substrate 20 having a short side length of 300 mm or more on the main surface can be used. Using the mask blank 10 of this embodiment, a transfer mask 100 can be manufactured having a transfer pattern including a thin film pattern 30a for forming a fine pattern having a width dimension and/or diameter dimension of, for example, less than 2.0 μm on a light-transmitting substrate 20. By using such a transfer mask 100 of this embodiment, it is possible to stably transfer a transfer pattern including a predetermined fine pattern to a transfer target object.

<Thin film 30 for pattern formation>
The thin film 30 for pattern formation of the mask blank 10 for manufacturing a display device according to this embodiment (hereinafter, may be simply referred to as "the mask blank 10 of this embodiment") contains a transition metal and silicon, and the X-ray absorption spectrum of the surface layer of the thin film 30 obtained by a total electron yield method is given by:
(IH-IL)/(EH-EL) is -6.0× ^10-4 or more.
Here, the surface layer refers to a region ranging from the surface opposite the light-transmitting substrate 20 to a depth of 10 nm toward the light-transmitting substrate 20 side, for example.
The slope of the X-ray absorption spectrum, (IH-IL)/(EH-EL), is preferably −2.0×10 ⁻⁴ or more, and more preferably −1.5×10 ⁻⁴ or more.

In general, the greater the X-ray energy, the less the X-rays are attenuated when propagating through a medium (the less easily they are absorbed within the medium). In other words, if the object being measured does not contain any elements that significantly absorb X-rays of a certain range of X-ray energies, the X-ray absorption spectrum will have a downward sloping (negative slope) spectrum with a smaller X-ray absorption coefficient as the X-ray energy increases. As the content of the element that significantly absorbs X-rays increases, the negative value of the slope of the X-ray absorption spectrum will become smaller and eventually turn positive. For this reason, there is no contradiction between the slope of the X-ray absorption spectrum (IH-IL)/(EH-EL) being a negative value (downward sloping) and the surface layer of the thin film of the object being measured containing argon.

The present inventors speculate as follows regarding the relationship between the tendency of the X-ray absorption coefficient and the light resistance.
At the stage where a pattern-forming thin film 30 containing transition metals and silicon is formed on a light-transmitting substrate 20 by sputtering with a sputtering gas containing argon in a film-forming chamber, it is considered that argon is taken in throughout the entire thickness direction of the thin film 30. On the other hand, considering the shape of the X-ray absorption spectrum derived from Ar obtained by the total electron yield method in FIG. 6, it is considered that after the light-transmitting substrate 20 on which the thin film 30 is formed is taken out of the film-forming chamber, the thin film 30 with low light resistance to exposure light including wavelengths in the ultraviolet region has relatively more argon desorbed and gaps are generated in the surface layer on the side exposed to the atmosphere than the thin film 30 with high light resistance. It is presumed that moisture in the atmosphere is adsorbed in the gaps, and the oxidation of silicon and transition metals in the surface layer progresses due to irradiation with exposure light, causing an increase in the transmittance of the thin film 30 and a shift in the film surface reflectance spectrum to the short wavelength side. However, this presumption is based on knowledge at the current stage and does not limit the scope of the rights of the present invention in any way.

The X-ray absorption spectrum obtained by the fluorescence yield method of the thin film 30 for pattern formation (hereinafter sometimes simply referred to as "thin film 30") is preferably such that the X-ray absorption coefficient at an incident X-ray energy EH of 3210 eV is greater than the X-ray absorption coefficient at an incident X-ray energy EL of 3180 eV.

In the X-ray absorption spectrum obtained by the fluorescence yield method in FIG. 5, the X-ray absorption coefficient tends to suddenly increase in the range of incident X-ray energy of 3180 to 3210 eV (more preferably in the range of 3200 to 3210 eV), so-called absorption edge (K absorption edge) appears. The absorption edge in this incident X-ray energy region is due to argon. In other words, a thin film with this tendency contains argon. On the other hand, among the thin films with clear differences in the X-ray absorption spectrum obtained by the total electron yield method in FIG. 6, there is no clear difference in the absorption edge related to argon in the X-ray absorption spectrum obtained by the fluorescence yield method in FIG. 5. From these facts, it can be said that a thin film in which the X-ray absorption coefficient at an incident X-ray energy EL of 3210 eV is larger than the X-ray absorption coefficient at an incident X-ray energy EL of 3180 eV in the X-ray absorption spectrum obtained by the fluorescence yield method contains argon in regions other than the surface layer of the thin film.

The pattern-forming thin film 30 may be made of a material containing a transition metal and silicon (Si). As the transition metal, molybdenum (Mo), tantalum (Ta), tungsten (W), titanium (Ti), zirconium (Zr), etc. are suitable, and titanium and molybdenum are more preferable. In addition, it is particularly preferable that the pattern-forming thin film 30 contains at least titanium as a transition metal.
This thin film 30 for pattern formation can be a phase shift film having a phase shift function.

The ratio of the transition metal content to the total content of the transition metal and silicon in the pattern-forming thin film 30 is preferably 0.05 or more, and more preferably 0.10 or more. By satisfying these ratios, it is possible to obtain excellent optical properties and chemical resistance. Furthermore, the ratio of the transition metal content to the total content of the transition metal and silicon in the pattern-forming thin film 30 is preferably 0.50 or less, and more preferably 0.40 or less. By satisfying these ratios, it is possible to suppress an excessive increase in the wet etching rate during pattern formation of the pattern-forming thin film 30.

The thin film 30 for pattern formation preferably contains nitrogen. In the above transition metal silicide, nitrogen, which is a light element component, has the effect of not lowering the refractive index compared to oxygen, which is also a light element component. Therefore, by containing nitrogen in the thin film 30 for pattern formation, the film thickness for obtaining the desired phase difference (also called the phase shift amount) can be made thin. In addition, the nitrogen content contained in the thin film 30 for pattern formation is preferably 10 atomic % or more, and more preferably 20 atomic % or more. On the other hand, the nitrogen content is preferably 60 atomic % or less, and more preferably 55 atomic % or less. A high nitrogen content in the thin film 30 can suppress excessively high transmittance for exposure light.

It is preferable that the thin film 30 for pattern formation contains argon in all regions in the thickness direction. A thin film 30 having higher light resistance against exposure light including wavelengths in the ultraviolet region is obtained. On the other hand, the thin film 30 for pattern formation may contain at least one element selected from argon, krypton, and xenon in all regions in the thickness direction. In this case, the relevant noble gas is contained in the sputtering gas used when forming the thin film 30 for pattern formation by sputtering. In addition, when the thin film 30 for pattern formation is formed in a sputtering gas containing krypton, it is preferable that the X-ray absorption spectrum of the thin film 30 obtained by the fluorescence yield method has a larger X-ray absorption coefficient at an incident X-ray energy EH of 14330 eV than the X-ray absorption coefficient at an incident X-ray energy EL of 14300 eV (in the case of the K absorption edge), or the X-ray absorption coefficient at an incident X-ray energy EH of 1680 eV is larger than the X-ray absorption coefficient at an incident X-ray energy EL of 1650 eV (in the case of the L3 absorption edge). Furthermore, when the thin film 30 for pattern formation is formed in a sputtering gas containing xenon, it is preferable that the X-ray absorption spectrum of the thin film 30 obtained by the fluorescence yield method has a larger X-ray absorption coefficient at an incident X-ray energy EH of 34570 eV than at an incident X-ray energy EL of 34540 eV (in the case of the K absorption edge), or the X-ray absorption coefficient at an incident X-ray energy EH of 4790 eV is larger than at an incident X-ray energy EL of 4760 eV (in the case of the L3 absorption edge).

On the other hand, when a thin film 30 for pattern formation is formed in a sputtering gas containing krypton, it is preferable that the X-ray absorption spectrum of the surface layer of the thin film 30 obtained by the total electron yield method has a larger X-ray absorption coefficient at an incident X-ray energy EH of 14,330 eV than at an incident X-ray energy EL of 14,300 eV (in the case of the K absorption edge), or that the X-ray absorption coefficient at an incident X-ray energy EH of 1,680 eV is larger than at an incident X-ray energy EL of 1,650 eV (in the case of the L3 absorption edge). In addition, when a thin film 30 for pattern formation is formed in a sputtering gas containing xenon, it is preferable that the X-ray absorption spectrum of the surface layer of the thin film 30 obtained by the total electron yield method has a larger X-ray absorption coefficient at an incident X-ray energy EH of 34570 eV than at an incident X-ray energy EL of 34540 eV (in the case of the K absorption edge), or that the X-ray absorption coefficient at an incident X-ray energy EH of 4790 eV is larger than at an incident X-ray energy EL of 4760 eV (in the case of the L3 absorption edge).

In addition to the oxygen and nitrogen described above, the thin film 30 for pattern formation may contain other light element components such as carbon and helium for the purpose of reducing film stress and/or controlling the wet etching rate.

The pattern-forming thin film 30 may be composed of multiple layers or may be composed of a single layer. A pattern-forming thin film 30 composed of a single layer is preferable in that an interface is unlikely to be formed in the pattern-forming thin film 30 and the cross-sectional shape is easy to control. On the other hand, a pattern-forming thin film 30 composed of multiple layers is preferable in that it is easy to form a film.
The thickness of the thin film 30 for pattern formation is preferably 200 nm or less, more preferably 180 nm or less, and even more preferably 150 nm or less in order to ensure optical performance. Also, the thickness of the thin film 30 for pattern formation is preferably 50 nm or more, and more preferably 60 nm or more in order to ensure a desired transmittance.

<<Transmittance and phase difference of thin film 30 for pattern formation>>
In the mask blank 10 for manufacturing a display device according to this embodiment, the thin film 30 for pattern formation is preferably a phase shift film having optical properties of a transmittance of 1% to 80% for the representative wavelength of exposure light (light with a wavelength of 405 nm: h-line) and a phase difference of 140 degrees to 210 degrees. Unless otherwise specified, the transmittance in this specification refers to a value calculated by taking the transmittance of the light-transmitting substrate as the standard (100%).

When the thin film 30 for pattern formation is a phase shift film, the thin film 30 for pattern formation has the function of adjusting the reflectance of light incident from the light-transmitting substrate 20 side (hereinafter, sometimes referred to as back surface reflectance) and the function of adjusting the transmittance and phase difference of the exposure light.

The transmittance of the thin film 30 for pattern formation with respect to the exposure light satisfies the value required for the thin film 30 for pattern formation. The transmittance of the thin film 30 for pattern formation with respect to light of a predetermined wavelength contained in the exposure light (hereinafter referred to as the representative wavelength) is preferably 1% to 80%, more preferably 3% to 65%, and even more preferably 5% to 60%. That is, when the exposure light is a composite light containing light in the wavelength range of 313 nm to 436 nm, the thin film 30 for pattern formation has the above-mentioned transmittance with respect to light of the 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 thin film 30 for pattern formation can have the above-mentioned transmittance with respect to any of the i-line, h-line, and g-line. The representative wavelength can be, for example, the h-line with a wavelength of 405 nm. By having such characteristics with respect to the h-line, when a composite light containing i-line, h-line, and g-line is used as the exposure light, a similar effect can be expected with respect to the transmittance at the wavelengths of the i-line and g-line.

In addition, when the exposure light is a monochromatic light selected by cutting a certain wavelength range from the wavelength range of 313 nm to 436 nm using a filter or the like, and when the exposure light is a monochromatic light selected from the wavelength range of 313 nm to 436 nm, the thin film 30 for pattern formation has the above-mentioned transmittance for the monochromatic light of that single wavelength.

The transmittance can be measured using a phase shift measurement device.

The phase difference of the thin film 30 for pattern formation with respect to the exposure light satisfies the value required for the thin film 30 for pattern formation. The phase difference of the thin film 30 for pattern formation is preferably 140 degrees or more and 210 degrees or less, more preferably 160 degrees or more and 200 degrees or less, and even more preferably 170 degrees or more and 190 degrees or less, with respect to the light of the representative wavelength contained in the exposure light. This property allows the phase of the light of the representative wavelength contained in the exposure light to be changed to 140 degrees or more and 210 degrees or less. Therefore, a phase difference of 140 degrees or more and 210 degrees or less occurs between the light of the representative wavelength transmitted through the thin film 30 for pattern formation and the light of the representative wavelength transmitted only through the translucent substrate 20. In other words, when the exposure light is a composite light including light in the wavelength range of 313 nm or more and 436 nm or less, the thin film 30 for pattern formation has the above-mentioned phase difference with respect to the light of the representative wavelength included in that wavelength range. For example, when the exposure light is a composite light including i-line, h-line, and g-line, the thin film 30 for pattern formation can have the above-mentioned phase difference with respect to any of the i-line, h-line, and g-line. The representative wavelength can be, for example, the h-line with a wavelength of 405 nm. By having such characteristics with respect to the h-line, a similar effect can be expected with respect to the phase difference at the wavelengths of the i-line and g-line when composite light including i-line, h-line, and g-line is used as the exposure light.

The phase difference can be measured using a phase shift measurement device.

The back surface reflectance of the thin film 30 for pattern formation is 15% or less in the wavelength range of 365 nm to 436 nm, and preferably 10% or less. When the exposure light includes the j-line (wavelength 313 nm), the back surface reflectance of the thin film 30 for pattern formation is preferably 20% or less for light in the wavelength range of 313 nm to 436 nm, and more preferably 17% or less. It is even more preferable that it is 15% or less. The back surface reflectance of the thin film 30 for pattern formation is 0.2% or more in the wavelength range of 365 nm to 436 nm, and preferably 0.2% or more for light in the wavelength range of 313 nm to 436 nm.

The back surface reflectance can be measured using a spectrophotometer, etc.

The thin film 30 for pattern formation can be formed by a known film formation method such as sputtering.

<Etching Mask Film 40>
The mask blank 10 for manufacturing a display device according to this embodiment preferably includes, on the thin film 30 for pattern formation, an etching mask film 40 having an etching selectivity different from that of the thin film 30 for pattern formation.

The etching mask film 40 is disposed on the upper side of the thin film 30 for pattern formation, and is made of a material that has etching resistance to the etching solution that etches the thin film 30 for pattern formation (has etching selectivity different from that of the thin film 30 for pattern formation). The etching mask film 40 can also have a function of blocking the transmission of exposure light. Furthermore, the etching mask film 40 may have a function of reducing the film surface reflectance of the thin film 30 for pattern formation to light incident from the side of the thin film 30 for pattern formation so that the film surface reflectance is 15% or less in the wavelength range of 350 nm to 436 nm.

The etching mask film 40 is preferably made of a chromium-based material containing chromium (Cr). More preferably, the etching mask film 40 is made of a material containing chromium and substantially free of silicon. Substantially free of silicon means that the silicon content is less than 2% (excluding the composition gradient region at the interface between the thin film 30 for pattern formation and the etching mask film 40). More specifically, the chromium-based material may be chromium (Cr) or a material containing chromium (Cr) and at least one of oxygen (O), nitrogen (N), and carbon (C). In addition, the chromium-based material may be a material containing chromium (Cr) and at least one of oxygen (O), nitrogen (N), and carbon (C), and further containing fluorine (F). For example, the material constituting the etching mask film 40 may be Cr, CrO, CrN, CrF, CrCO, CrCN, CrON, CrCON, and CrCONF.

The etching mask film 40 can be formed by a known film formation method such as sputtering.

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

The etching mask film 40 can be a single film with a uniform composition depending on the function. The etching mask film 40 can also be a plurality of films with different compositions. The etching mask film 40 can also be a single film whose composition changes continuously in the thickness direction.

The mask blank 10 of this embodiment shown in FIG. 1 includes an etching mask film 40 on a thin film 30 for pattern formation. The mask blank 10 of this embodiment includes a mask blank 10 having a structure in which an etching mask film 40 is provided on a thin film 30 for pattern formation, and a resist film is provided on the etching mask film 40.

<Method of Manufacturing Mask Blank 10>
Next, a method for manufacturing the mask blank 10 of the embodiment shown in Fig. 1 will be described. The mask blank 10 shown in Fig. 1 is manufactured by carrying out the following thin film formation process for pattern formation and etching mask film formation process. The mask blank 10 shown in Fig. 2 is manufactured by the thin film formation process for pattern formation.

Each step is explained in detail below.

<<Process for forming thin film for pattern formation>>
First, prepare the light-transmitting substrate 20. The light-transmitting substrate 20 can be made of a glass material selected from synthetic quartz glass, quartz glass, aluminosilicate glass, soda-lime glass, low-thermal expansion glass (SiO ₂ —TiO ₂ glass, etc.), etc., so long as it is transparent to the exposure light.

Next, a thin film 30 for pattern formation is formed on the light-transmitting substrate 20 by sputtering.

The thin film 30 for pattern formation can be formed in a predetermined sputtering gas atmosphere using a predetermined sputtering target. The predetermined sputtering target is, for example, a transition metal silicide target containing a transition metal and silicon, which are the main components of the material constituting the thin film 30 for pattern formation, or a transition metal silicon nitride target containing a transition metal, silicon, and nitrogen. The predetermined sputtering gas atmosphere is, for example, a sputtering gas atmosphere consisting of an inert gas containing argon gas, or a sputtering gas atmosphere consisting of a mixed gas containing the above-mentioned inert gas, nitrogen gas, and, in some cases, a gas selected from the group consisting of oxygen gas, carbon dioxide gas, nitric oxide gas, and nitrogen dioxide gas. The thin film 30 for pattern formation can be formed in a state in which the gas pressure in the film formation chamber during sputtering is 0.3 Pa or more and 2.0 Pa or less, preferably 0.43 Pa or more and 0.9 Pa or less. Side etching during pattern formation can be suppressed and a high etching rate can be achieved. From the standpoint of improving light resistance and adjusting transmittance, the atomic ratio of transition metal to silicon in the transition metal silicide target is preferably in the range of transition metal:silicon = 1:1 to 1:19.

The composition and thickness of the pattern-forming thin film 30 are adjusted so that the pattern-forming thin film 30 has the above-mentioned phase difference and transmittance. The composition of the pattern-forming thin film 30 can be controlled by the content ratio of the elements constituting the sputtering target (for example, the ratio of the transition metal content to the silicon content), the composition and flow rate of the sputtering gas, and the like. The thickness of the pattern-forming thin film 30 can be controlled by the sputtering power, the sputtering time, and the like. In addition, the pattern-forming thin film 30 is preferably formed using an in-line sputtering device. When the sputtering device is an in-line sputtering device, the thickness of the pattern-forming thin film 30 can also be controlled by the conveying speed of the substrate. In this way, the X-ray absorption spectrum of the pattern-forming thin film 30 is controlled so as to satisfy a desired relationship (such as a relationship in which (IH-IL)/(EH-EL) is -6.0×10 ^-4 or more).

When the thin film 30 for pattern formation consists of a single film, the above-mentioned film formation process is performed only once by appropriately adjusting the composition and flow rate of the sputtering gas. When the thin film 30 for pattern formation consists of multiple films with different compositions, the above-mentioned film formation process is performed multiple times by appropriately adjusting the composition and flow rate of the sputtering gas. The thin film 30 for pattern formation may be formed using targets with different content ratios of the elements that make up the sputtering target. When the film formation process is performed multiple times, the sputtering power applied to the sputtering target may be changed for each film formation process.

In this manner, the mask blank 10 of this embodiment can be obtained.

<<Etching mask film forming process>>
The mask blank 10 of this embodiment may further include an etching mask film 40. The following etching mask film forming step is further performed. The etching mask film 40 is preferably made of a material containing chromium.

After the pattern-forming thin film formation process, a surface treatment is performed as necessary to adjust the surface oxidation state of the surface of the pattern-forming thin film 30, and then an etching mask film 40 is formed on the pattern-forming thin film 30 by a sputtering method. The etching mask film 40 is preferably formed using an in-line sputtering device. When the sputtering device is an in-line sputtering device, the thickness of the etching mask film 40 can also be controlled by the transport speed of the light-transmitting substrate 20.

The etching mask film 40 can be formed in a sputtering gas atmosphere consisting of an inert gas or a mixture of an inert gas and an active gas, using a sputtering target containing chromium or a chromium compound (chromium oxide, chromium nitride, chromium carbide, chromium oxynitride, chromium nitride carbonitride, chromium oxynitride carbonitride, etc.). The inert gas can include at least one selected from the group consisting of helium gas, neon gas, argon gas, krypton gas, and xenon gas. The active gas can include at least one selected from the group consisting of oxygen gas, nitrogen gas, nitric oxide gas, nitrogen dioxide gas, hydrocarbon gas, and fluorine gas. Examples of the hydrocarbon gas include methane gas, butane gas, propane gas, and styrene gas. By adjusting the gas pressure in the film formation chamber during sputtering, the etching mask film 40 can be made to have a columnar structure similar to the thin film 30 for pattern formation. This makes it possible to suppress side etching during pattern formation, which will be described later, and to achieve a high etching rate.

When the etching mask film 40 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. When the etching mask film 40 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. When the etching mask film 40 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 manner, the mask blank 10 of this embodiment having an etching mask film 40 can be obtained.

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

In the mask blank 10 of the embodiment shown in Fig. 1, an etching mask film 40 is formed on a thin film 30 for pattern formation. In the mask blank 10 of the embodiment shown in Fig. 2, a thin film 30 for pattern formation is formed. In either case, the thin film 30 for pattern formation has an X-ray absorption spectrum that satisfies a desired relationship (e.g., (IH-IL)/(EH-EL) is -6.0 x ^10-4 or more) in its surface layer.

The mask blank 10 of the embodiment shown in FIGS. 1 and 2 has high light resistance to exposure light including wavelengths in the ultraviolet region.
Therefore, by using the mask blank 10 of this embodiment, it is possible to manufacture a transfer mask 100 that has high light resistance to exposure light including wavelengths in the ultraviolet region and is capable of accurately transferring a thin film pattern 30a for forming a highly precise pattern.

<Method of Manufacturing Transfer Mask 100>
Next, a method for manufacturing the transfer mask 100 of this embodiment will be described. This transfer mask 100 has the same technical features as the mask blank 10. The matters relating to the light-transmitting substrate 20, the thin film for pattern formation 30, and the etching mask film 40 in the transfer mask 100 are the same as those in the mask blank 10.

Figure 3 is a schematic diagram showing a method for manufacturing the transfer mask 100 of this embodiment. Figure 4 is a schematic diagram showing another method for manufacturing the transfer mask 100 of this embodiment.

<<Method of Manufacturing the Transfer Mask 100 Shown in FIG. 3>>
The method for manufacturing the transfer mask 100 shown in FIG. 3 is a method for manufacturing the transfer mask 100 using the mask blank 10 shown in FIG. 1. The method for manufacturing the transfer mask 100 shown in FIG. 3 includes the steps of preparing the mask blank shown in FIG. 1, forming a resist film having a transfer pattern on the etching mask film 40, performing wet etching to mask the resist film and form a transfer pattern on the etching mask film 40, and performing wet etching using the etching mask film (first etching mask film pattern 40a) on which the transfer pattern is formed as a mask to form a transfer pattern on the thin film 30 for pattern formation. Note that the transfer pattern in this specification is obtained by patterning at least one optical film formed on the light-transmitting substrate 20. The optical film may be the thin film 30 for pattern formation and/or the etching mask film 40, and may further include other films (such as a light-shielding film, a film for suppressing reflection, and a conductive film). That is, the transfer pattern may include a patterned thin film for pattern formation and/or an etching mask film, and may further include other patterned films.

The manufacturing method of the transfer mask 100 shown in FIG. 3 specifically includes forming a resist film on the etching mask film 40 of the mask blank 10 shown in FIG. 1. Next, a desired pattern is drawn and developed on the resist film to form a resist film pattern 50 (see FIG. 3(a) , forming a first resist film pattern 50). Next, the etching mask film 40 is wet-etched using the resist film pattern 50 as a mask to form an etching mask film pattern 40a on the thin film 30 for pattern formation (see FIG. 3(b) , forming a first etching mask film pattern 40a). Next, the thin film 30 for pattern formation is wet-etched using the etching mask film pattern 40a as a mask to form a thin film pattern 30a for pattern formation on the light-transmitting substrate 20 (see FIG. 3(c) , forming a thin film pattern 30a for pattern formation). After that, the method may further include forming a second resist film pattern 60 and forming a second etching mask film pattern 40b (see FIG. 3(d) and (e)).

More specifically, in the process of forming the first resist film pattern 50, a resist film is first formed on the etching mask film 40 of the mask blank 10 of this embodiment shown in FIG. 1. There are no particular limitations on the resist film material used. The resist film may be any material that is sensitive to laser light having a wavelength selected from the wavelength range of 350 nm to 436 nm described below. The resist film may be either positive or negative.

Then, a desired pattern is drawn on the resist film using laser light having a wavelength selected from the wavelength range of 350 nm to 436 nm. The pattern drawn on the resist film is the pattern to be formed on the thin film 30 for pattern formation. Examples of patterns drawn on the resist film include a line and space pattern and a hole pattern.

The resist film is then developed with a predetermined developer to form a first resist film pattern 50 on the etching mask film 40, as shown in FIG. 3(a).

<<<<Step of Forming First Etching Mask Film Pattern 40a>>>
In the step of forming the first etching mask film pattern 40a, first, the etching mask film 40 is etched using the first resist film pattern 50 as a mask to form the first etching mask film pattern 40a. The etching mask film 40 can be formed from a chromium-based material containing chromium (Cr).

Then, as shown in FIG. 3(b), the first resist film pattern 50 is stripped using a resist stripper or by ashing. In some cases, the process of forming the thin film pattern 30a for the next pattern formation may be performed without stripping the first resist film pattern 50.

<<<<Process for forming thin film pattern 30a for pattern formation>>>
In the step of forming the first pattern-forming thin film pattern 30a, the pattern-forming thin film 30 is wet-etched using the first etching mask film pattern 40a as a mask to form the pattern-forming thin film pattern 30a as shown in FIG. 3(c). Examples of the pattern-forming thin film pattern 30a include a line-and-space pattern and a hole pattern. The etching solution for etching the pattern-forming thin film 30 is not particularly limited as long as it can selectively etch the pattern-forming thin film 30. For example, an etching solution containing ammonium hydrogen fluoride and hydrogen peroxide, or an etching solution containing ammonium fluoride, phosphoric acid, and hydrogen peroxide may be used.

In order to improve the cross-sectional shape of the thin film pattern 30a for pattern formation, it is preferable to perform wet etching for a time (over-etching time) longer than the time until the light-transmitting substrate 20 is exposed in the thin film pattern 30a for pattern formation (just-etching time). Considering the effect on the light-transmitting substrate 20, the over-etching time is preferably within the just-etching time plus 20% of the just-etching time, and more preferably within 10% of the just-etching time.

<<<<Step of Forming Second Resist Film Pattern 60>>>
In the process of forming the second resist film pattern 60, first, a resist film is formed to cover the first etching mask film pattern 40a. There are no particular limitations on the resist film material used. For example, any material that is sensitive to laser light having a wavelength selected from the wavelength range of 350 nm to 436 nm described below may be used. The resist film may be either positive or negative.

Then, a desired pattern is drawn on the resist film using a laser beam having a wavelength selected from the wavelength range of 350 nm to 436 nm. The pattern drawn on the resist film may be a light-shielding band pattern that blocks the outer peripheral region of the region in which the thin film pattern 30a for pattern formation is formed, and a light-shielding band pattern that blocks the center of the thin film pattern 30a for pattern formation. Note that, depending on the transmittance of the thin film 30 for pattern formation to the exposure light, the pattern drawn on the resist film may not have a light-shielding band pattern that blocks the center of the thin film pattern 30a for pattern formation.

The resist film is then developed with a predetermined developer to form a second resist film pattern 60 on the first etching mask film pattern 40a, as shown in FIG. 3(d).

<<<<Step of Forming Second Etching Mask Film Pattern 40b>>>
In the process of forming the second etching mask film pattern 40b, the first etching mask film pattern 40a is etched using the second resist film pattern 60 as a mask to form the second etching mask film pattern 40b as shown in FIG. 3(e). The first etching mask film pattern 40a can be made of a chromium-based material containing chromium (Cr). The etching solution for etching the first etching mask film pattern 40a is not particularly limited as long as it can selectively etch the first etching mask film pattern 40a. For example, an etching solution containing ceric ammonium nitrate and perchloric acid can be used.

Then, the second resist film pattern 60 is stripped using a resist stripper or by ashing.

In this manner, the transfer mask 100 can be obtained. That is, the transfer pattern of the transfer mask 100 according to this embodiment can include a thin film pattern 30a for pattern formation and a second etching mask film pattern 40b.

In the above description, the etching mask film 40 has the function of blocking the transmission of exposure light. In the case where the etching mask film 40 only functions as a hard mask when etching the thin film 30 for pattern formation, the process of forming the second resist film pattern 60 and the process of forming the second etching mask film pattern 40b are not performed in the above description. In this case, after the process of forming the thin film pattern 30a for pattern formation, the first etching mask film pattern 40a is peeled off to produce the transfer mask 100. In other words, the transfer pattern of the transfer mask 100 may be composed only of the thin film pattern 30a for pattern formation.

The method for manufacturing the transfer mask 100 of this embodiment uses the mask blank 10 shown in FIG. 1, so that it is possible to manufacture a transfer mask 100 that has high light resistance to exposure light including wavelengths in the ultraviolet region and can accurately transfer a thin film pattern 30a for forming a highly precise pattern. The transfer mask 100 manufactured in this manner can accommodate miniaturization of line and space patterns and/or contact holes.

<<Method of Manufacturing the Transfer Mask 100 Shown in FIG. 4>>
The method for manufacturing the transfer mask 100 shown in Fig. 4 is a method for manufacturing the transfer mask 100 using the mask blank 10 shown in Fig. 2. The method for manufacturing the transfer mask 100 shown in Fig. 4 includes the steps of preparing the mask blank 10 shown in Fig. 2, forming a resist film on the thin film 30 for pattern formation, and wet-etching the thin film 30 for pattern formation using the resist film pattern as a mask, thereby forming a transfer pattern on the light-transmitting substrate 20.

Specifically, in the method for manufacturing the transfer mask 100 shown in FIG. 4, a resist film is formed on the mask blank 10. Next, a desired pattern is drawn and developed on the resist film to form a resist film pattern 50 (FIG. 4(a), the step of forming a first resist film pattern 50). Next, the resist film pattern 50 is used as a mask to wet etch the thin film 30 for pattern formation, forming a thin film pattern 30a for pattern formation on the light-transmitting substrate 20 (FIGS. 4(b) and (c), the step of forming a thin film pattern 30a for pattern formation).

More specifically, in the resist film pattern forming process, a resist film is first formed on the thin film 30 for pattern formation of the mask blank 10 of this embodiment shown in FIG. 2. The resist film material used is the same as that described above. If necessary, before forming the resist film, a surface modification treatment can be performed on the thin film 30 for pattern formation in order to improve the adhesion between the thin film 30 for pattern formation and the resist film. As described above, after forming the resist film, a desired pattern is drawn on the resist film using a laser beam having a wavelength selected from the wavelength range of 350 nm to 436 nm. The resist film is then developed with a specified developer to form a resist film pattern 50 on the thin film 30 for pattern formation, as shown in FIG. 4(a).

<<<<Process for forming thin film pattern 30a for pattern formation>>>
In the process of forming the thin film pattern 30a for pattern formation, the thin film 30 for pattern formation is etched using the resist film pattern as a mask to form the thin film pattern 30a for pattern formation as shown in Fig. 4(b). The etching solution and overetching time for etching the thin film pattern 30a for pattern formation and the thin film 30 for pattern formation are the same as those described in the embodiment shown in Fig. 3 above.

Then, the resist film pattern 50 is stripped using a resist stripper or by ashing (Figure 4(c)).

In this manner, the transfer mask 100 can be obtained. Note that the transfer pattern of the transfer mask 100 in this embodiment is composed only of the thin film pattern 30a for pattern formation, but it can also include other film patterns. Examples of other films include a film that suppresses reflection, a conductive film, etc.

According to the method for manufacturing the transfer mask 100 of this embodiment, the mask blank 10 shown in FIG. 2 is used, so that the transfer mask 100 can be manufactured that has high light resistance to exposure light including wavelengths in the ultraviolet region and can accurately transfer the thin film pattern 30a for forming a highly precise pattern. The transfer mask 100 manufactured in this manner can accommodate miniaturization of line and space patterns and/or contact holes.

<Display Device Manufacturing Method>
A method for manufacturing the display device of this embodiment will be described. The method for manufacturing the display device of this embodiment includes an exposure process in which the above-mentioned transfer mask 100 of this embodiment is placed on a mask stage of an exposure device, and a transfer pattern formed on the transfer mask 100 for manufacturing the display device is exposed and transferred to a resist formed on a substrate for the display device.

Specifically, the manufacturing method of the display device of this embodiment includes a process of placing the transfer mask 100 manufactured using the above-mentioned mask blank 10 on a mask stage of an exposure device (mask placing process), and a process of transferring a transfer pattern to a resist film on a substrate for the display device (exposure process). Each process will be described in detail below.

<<Placement process>>
In the placing step, the transfer mask 100 of this embodiment is placed on a mask stage of an exposure tool. Here, the transfer mask 100 is disposed so as to face a resist film formed on a substrate for a display device via a projection optical system of the exposure tool.

<<Pattern transfer process>>
In the pattern transfer process, the transfer mask 100 is irradiated with exposure light, and a transfer pattern including a thin film pattern 30a for pattern formation is transferred to a resist film formed on a substrate for a display device. The exposure light is a composite light including a plurality of wavelengths selected from a wavelength range of 313 nm to 436 nm, or a monochromatic light selected by cutting a certain wavelength range from the wavelength range of 313 nm to 436 nm using a filter or the like, or a monochromatic light emitted from a light source having a wavelength range of 313 nm to 436 nm. For example, the exposure light is a composite light including at least one of i-line, h-line, and g-line, or a monochromatic light of i-line. By using a composite light as the exposure light, the exposure light intensity can be increased to improve the throughput. Therefore, the manufacturing cost of the display device can be reduced.

According to the manufacturing method of the display device of this embodiment, it is possible to manufacture a high-definition display device having high resolution, fine line and space patterns and/or contact holes.

In the above embodiment, the mask blank 10 having the thin film 30 for pattern formation and the transfer mask 100 having the thin film pattern 30a for pattern formation are described. The thin film 30 for pattern formation can be, for example, a phase shift film having a phase shift effect, or a light-shielding film. Therefore, the transfer mask 100 of this embodiment includes a phase shift mask having a phase shift film pattern and a binary mask having a light-shielding film pattern. Furthermore, the mask blank 10 of this embodiment includes a phase shift mask blank and a binary mask blank that are the raw materials for the phase shift mask and the binary mask.

The present invention will be described in detail below with reference to examples, but the present invention is not limited to these.

Example 1
To manufacture the mask blank 10 of Example 1, first, a synthetic quartz glass substrate having a size of 1214 (1220 mm×1400 mm) was prepared as the light-transmitting substrate 20 .

The synthetic quartz glass substrate was then placed on a tray (not shown) with its main surface facing downwards and was then transported into the chamber of an in-line sputtering device.

In order to form a pattern-forming thin film 30 on the main surface of the light-transmitting substrate 20, a mixed gas consisting of argon (Ar) gas and nitrogen (N ₂ ) gas was first introduced into the first chamber. Then, a titanium silicide nitride containing titanium, silicon, and nitrogen was deposited on the main surface of the light-transmitting substrate 20 by reactive sputtering using a first sputtering target containing titanium and silicon. In this manner, a pattern-forming thin film 30 (Ti:Si:N:O=10.7:34.9:50.3:4.1 atomic % ratio) having a thickness of 113 nm and made of titanium silicide nitride was formed. Here, the composition of the pattern-forming thin film 30 is the result obtained by measuring a thin film formed under the same film-forming conditions as in Example 1 using X-ray photoelectron spectroscopy (XPS). The same method of measuring the film composition was used for other films (similar to Examples 2 and 3, and Comparative Examples 1 and 2). The ratio of the titanium content to the total content of titanium and silicon in this pattern-forming thin film 30 was 0.235, which was greater than or equal to 0.05.
The thin film 30 for pattern formation is a phase shift film having a phase shift effect.

Next, the light-transmitting substrate 20 with the thin film 30 for pattern formation was carried into the second chamber, and a mixed gas of argon (Ar) gas and nitrogen (N ₂ ) gas was introduced into the second chamber. Then, using a second sputtering target made of chromium, chromium nitride (CrN) containing chromium and nitrogen was formed on the thin film 30 for pattern formation by reactive sputtering. Next, with the third chamber in a predetermined vacuum state, a mixed gas of argon (Ar) gas and methane (CH ₄ ) gas was introduced, and using a third sputtering target made of chromium, chromium carbide (CrC) containing chromium and carbon was formed on the CrN by reactive sputtering. Finally, in a state where the inside of the fourth chamber was kept at a predetermined vacuum level, a mixed gas of argon (Ar) gas and methane ( _CH4 ) gas, nitrogen ( _N2 ) gas and oxygen ( _O2 ) gas was introduced, and chromium carbide-oxynitride (CrCON) containing chromium, carbon, oxygen and nitrogen was formed on CrC by reactive sputtering using a fourth sputtering target made of chromium. As described above, an etching mask film 40 having a laminated structure of a CrN layer, a CrC layer and a CrCON layer was formed on the thin film 30 for pattern formation.

In this way, a mask blank 10 was obtained in which a thin film 30 for pattern formation and an etching mask film 40 were formed on a light-transmitting substrate 20.

The thin film for pattern formation of Example 1 was formed on the main surface of another synthetic quartz substrate (approximately 152 mm x approximately 152 mm), and another thin film for pattern formation was formed under the same film formation conditions as in Example 1 above. Next, X-ray absorption fine structure analysis was performed by X-ray absorption spectroscopy (total electron yield method, fluorescence yield method) on a sample cut to a predetermined size from the thin film for pattern formation on that other synthetic quartz substrate, and an X-ray absorption spectrum was obtained. Specifically, this was performed at the Aichi Synchrotron Light Center BL6N1 (the same applies to the following Examples 2 and 3, and Comparative Examples 1 and 2).

Figure 5 shows the Ar-derived X-ray absorption spectrum (horizontal axis: X-ray energy incident on the thin film, vertical axis: X-ray absorption coefficient of the thin film for that X-ray energy) obtained by the fluorescence yield method for the thin film for pattern formation of the mask blanks according to Examples 1 to 3 and Comparative Examples 1 and 2 of the present invention. As shown in Figure 5, in the Ar-derived X-ray absorption spectrum obtained by the fluorescence yield method of Example 1, the X-ray absorption coefficient at an incident X-ray energy EH of 3210 eV is larger than the X-ray absorption coefficient at an incident X-ray energy EL of 3180 eV, confirming that Ar is present in at least some region in the thickness direction of the thin film 30.

FIG. 6 is a diagram showing X-ray absorption spectra derived from Ar obtained by a total electron yield method for the surface layers of the thin films for pattern formation of the mask blanks according to Examples 1 to 3 of the present invention and Comparative Examples 1 and 2 (horizontal axis: X-ray energy incident on the surface layer of the thin film, vertical axis: X-ray absorption coefficient of the surface layer of the thin film for X-rays of that energy).
6, the X-ray absorption spectrum of the surface layer of the thin film 30 in Example 1 had a (IH-IL)/(EH-EL) of 7.933× ^10-4 , which satisfied the relationship of -6.0× ^10-4 or more. Here, IL is the X-ray absorption coefficient when the incident X-ray energy EL is 3180 eV, and IH is the X-ray absorption coefficient when the incident X-ray energy EH is 3210 eV (the same applies to the following Examples 2 and 3 and Comparative Examples 1 and 2).
Furthermore, as shown in FIG. 6, in the X-ray absorption spectrum of the surface layer of the thin film 30 in Example 1, the X-ray absorption coefficient IH at the incident X-ray energy EH of 3210 eV was larger than the X-ray absorption coefficient IL at the incident X-ray energy EL of 3180 eV.

<Measurement of transmittance and phase difference>
The transmittance (wavelength: 405 nm) and phase difference (wavelength: 405 nm) were measured for the surface of the pattern-forming thin film 30 of the mask blank 10 of Example 1. To measure the transmittance and phase difference of the pattern-forming thin film 30, a thin-film-attached substrate in which another thin film for pattern formation was formed on the main surface of the above-mentioned other synthetic quartz glass substrate was used (the same applies to the following Examples 2 and 3 and Comparative Examples 1 and 2). As a result, the transmittance of the other thin film for pattern formation (thin film for pattern formation 30) in Example 1 was 35.2%, and the phase difference was 140 degrees.

<Transfer Mask 100 and Its Manufacturing Method>
A transfer mask 100 was manufactured using the mask blank 10 of Example 1 manufactured as described above. First, a photoresist film was applied onto the etching mask film 40 of this mask blank 10 using a resist application device.

After that, a heating and cooling process was performed to form a photoresist film.

After that, a photoresist film was drawn using a laser drawing device, and after a development and rinsing process, a resist film pattern with a hole pattern having a hole diameter of 1.5 μm was formed on the etching mask film 40.

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

Then, using the first etching mask film pattern 40a as a mask, the thin film 30 for pattern formation was wet-etched with a titanium silicide etching solution made of a mixture of ammonium hydrogen fluoride and hydrogen peroxide diluted with pure water to form a thin film pattern 30a for pattern formation.

The resist film pattern was then peeled off.

Then, a photoresist film was applied using a resist coating device to cover the first etching mask film pattern 40a.

After that, a heating and cooling process was performed to form a photoresist film.

After that, a photoresist film was drawn using a laser drawing device, and after a development and rinsing process, a second resist film pattern 60 for forming a light-shielding zone was formed on the first etching mask film pattern 40a.

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

Then, the second resist film pattern 60 was peeled off.

In this way, the transfer mask 100 of Example 1 was obtained, in which a thin film pattern 30a for pattern formation with a hole diameter of 1.5 μm was formed in the transfer pattern formation region on the light-transmitting substrate 20, and a light-shielding band consisting of a laminated structure of the thin film pattern 30a for pattern formation and the etching mask film pattern 40b was formed.

<Cross-sectional shape of transfer mask 100>
The cross section of the resulting transfer mask 100 was observed with a scanning electron microscope.
The pattern-forming thin film pattern 30a of the transfer mask 100 of Example 1 had a cross-sectional shape that was nearly vertical. Therefore, the pattern-forming thin film pattern 30a formed on the transfer mask 100 of Example 1 had a cross-sectional shape that could fully exhibit the phase shift effect.

From the above, it can be said that when the transfer mask 100 of Example 1 is set on the mask stage of an exposure device and exposed and transferred onto a resist film on a substrate for a display device, a transfer pattern including a fine pattern of less than 2.0 μm can be transferred with high precision.

<Light resistance>
A sample was prepared by forming the thin film 30 for pattern formation used in the mask blank 10 of Example 1 on a light-transmitting substrate 20. The thin film 30 for pattern formation of the sample of Example 1 was irradiated with light from a metal halide light source containing ultraviolet light with a wavelength of 405 nm to a total irradiation dose of 10 kJ/ ^cm2 . The transmittance was measured before and after irradiation with a predetermined amount of ultraviolet light, and the change in transmittance [(transmittance after ultraviolet light irradiation) - (transmittance before ultraviolet light irradiation)] was calculated to evaluate the light resistance of the thin film 30 for pattern formation. The transmittance was measured using a spectrophotometer.

Figure 7 shows the relationship between (IH-IL)/(EH-EL) and the change in transmittance in the thin film for pattern formation of the mask blanks according to Examples 1 to 3 of the present invention and Comparative Examples 1 and 2. As shown in Figure 7, in Example 1, the change in transmittance before and after UV irradiation was a favorable 0.34%. From the above, it was found that the thin film for pattern formation in Example 1 is a film with sufficient light resistance for practical use.

From the above, it has become clear that the thin film for pattern formation of Example 1 is an unprecedentedly excellent product that satisfies the requirements for high light resistance to exposure light including wavelengths in the ultraviolet region while also satisfying the desired optical properties (transmittance, phase difference).

Example 2
The mask blank 10 of Example 2 was produced in the same manner as the mask blank 10 of Example 1, except that the thin film 30 for pattern formation was prepared as follows.
The method for forming the thin film 30 for pattern formation in the second embodiment is as follows.
In order to form a pattern-forming thin film 30 on the main surface of the light-transmitting substrate 20, a mixed gas consisting of argon (Ar) gas and nitrogen (N ₂ ) gas was first introduced into the first chamber. Then, a titanium silicide nitride containing titanium, silicon, and nitrogen was deposited on the main surface of the light-transmitting substrate 20 by reactive sputtering using a first sputtering target containing titanium and silicon. In this way, a pattern-forming thin film 30 (Ti:Si:N:O=10.2:36.2:52.7:0.9 atomic % ratio) having a thickness of 126 nm and made of titanium silicide nitride was formed. The ratio of the titanium content to the total content of titanium and silicon in this pattern-forming thin film 30 was 0.220, which was 0.05 or more.
Thereafter, in the same manner as in the first embodiment, an etching mask film 40 was formed.

Then, on the main surface of another synthetic quartz substrate, another thin film for pattern formation was formed under the same film formation conditions as in Example 2. Next, for a sample cut to a predetermined size from the thin film for pattern formation on this other synthetic quartz substrate, X-ray absorption fine structure analysis was performed by X-ray absorption spectroscopy (total electron yield method, fluorescence yield method) in the same manner as in Example 1, and an X-ray absorption spectrum was obtained.
As shown in FIG. 5 , in the X-ray absorption spectrum derived from Ar obtained by the fluorescence yield method of Example 2, the X-ray absorption coefficient at the incident X-ray energy EH of 3210 eV is larger than the X-ray absorption coefficient at the incident X-ray energy EL of 3180 eV, and it was confirmed that Ar is present in at least some region of the thin film 30 in the thickness direction.
As can be determined from the values shown in FIG. 6, the X-ray absorption spectrum of the surface layer of the thin film 30 in Example 2 had a (IH-IL)/(EH-EL) ratio of 1.500×10 ⁻⁴ , which satisfied the relationship of −6.0×10 ⁻⁴ or more.
As shown in FIG. 6, in the X-ray absorption spectrum of the surface layer of the thin film 30 in Example 2, the X-ray absorption coefficient IH at the incident X-ray energy EH of 3210 eV was larger than the X-ray absorption coefficient IL at the incident X-ray energy EL of 3180 eV.

<Measurement of transmittance and phase difference>
The transmittance (wavelength: 405 nm) and phase difference (wavelength: 405 nm) were measured for the surface of the pattern-forming thin film 30 of the mask blank 10 of Example 2. As a result, the transmittance of the pattern-forming thin film 30 in Example 2 was 30.9%, and the phase difference was 151 degrees.

<Transfer Mask 100 and Its Manufacturing Method>
Using the mask blank 10 of Example 2 manufactured as described above, a transfer mask 100 was manufactured in the same manner as in Example 1, to obtain a transfer mask 100 of Example 2 in which a thin film pattern 30a for pattern formation having a hole diameter of 1.5 μm in the transfer pattern formation region and a light-shielding band consisting of a laminated structure of the thin film pattern 30a for pattern formation and the etching mask film pattern 40b were formed on the light-transmitting substrate 20.

<Cross-sectional shape of transfer mask 100>
The cross section of the resulting transfer mask 100 was observed with a scanning electron microscope.
The pattern-forming thin film pattern 30a of the transfer mask 100 of Example 2 had a cross-sectional shape that was nearly vertical. Therefore, the pattern-forming thin film pattern 30a formed on the transfer mask 100 of Example 2 had a cross-sectional shape that could fully exert the phase shift effect.

From the above, it can be said that when the transfer mask 100 of Example 2 is set on the mask stage of an exposure device and exposed and transferred onto a resist film on a substrate for a display device, a transfer pattern including a fine pattern of less than 2.0 μm can be transferred with high precision.

<Light resistance>
A sample was prepared by forming the thin film 30 for pattern formation used in the mask blank 10 of Example 2 on a light-transmitting substrate 20. The thin film 30 for pattern formation of the sample of Example 2 was irradiated with light from a metal halide light source containing ultraviolet light with a wavelength of 405 nm to a total irradiation dose of 10 kJ/ ^cm2 . The transmittance was measured before and after irradiation with a predetermined amount of ultraviolet light, and the change in transmittance [(transmittance after ultraviolet light irradiation) - (transmittance before ultraviolet light irradiation)] was calculated to evaluate the light resistance of the thin film 30 for pattern formation. The transmittance was measured using a spectrophotometer.

As shown in FIG. 7, in Example 2, the change in transmittance before and after UV irradiation was a favorable 0.37%. From the above, it was found that the thin film for pattern formation in Example 2 was a film with sufficient light resistance for practical use.

From the above, it has become clear that the thin film for pattern formation of Example 2 is an unprecedentedly excellent product that satisfies the requirements for high light resistance to exposure light including wavelengths in the ultraviolet region while also satisfying the desired optical properties (transmittance, phase difference).

Example 3
The mask blank 10 of Example 3 was produced in the same manner as the mask blank 10 of Example 1, except that the thin film 30 for pattern formation was prepared as follows.
The method for forming the thin film 30 for pattern formation in the third embodiment is as follows.
In order to form a pattern-forming thin film 30 on the main surface of the light-transmitting substrate 20, a mixed gas consisting of argon (Ar) gas and nitrogen (N ₂ ) gas was first introduced into the first chamber. Then, a titanium silicide nitride containing titanium, silicon, and nitrogen was deposited on the main surface of the light-transmitting substrate 20 by reactive sputtering using a first sputtering target containing titanium and silicon. In this way, a pattern-forming thin film 30 (Ti:Si:N:O=11.4:35.4:52.4:0.8 atomic % ratio) having a thickness of 109 nm and made of titanium silicide nitride was formed. The ratio of the titanium content to the total content of titanium and silicon in this pattern-forming thin film 30 was 0.244, which was 0.05 or more.
Thereafter, in the same manner as in the first embodiment, an etching mask film 40 was formed.

Then, on the main surface of another synthetic quartz substrate, another thin film for pattern formation was formed under the same film formation conditions as in Example 3. Next, for a sample cut to a predetermined size from the thin film for pattern formation on this other synthetic quartz substrate, X-ray absorption fine structure analysis was performed by X-ray absorption spectroscopy (total electron yield method, fluorescence yield method) in the same manner as in Example 1, and an X-ray absorption spectrum was obtained.
As shown in FIG. 5 , in the X-ray absorption spectrum originating from Ar obtained by the fluorescence yield method of Example 3, the X-ray absorption coefficient at the incident X-ray energy EH of 3210 eV is larger than the X-ray absorption coefficient at the incident X-ray energy EL of 3180 eV, and it was confirmed that Ar is present in at least some region of the thin film 30 in the thickness direction.
As can be determined from the values shown in FIG. 6, the X-ray absorption spectrum of the surface layer of the thin film 30 in Example 3 had an (IH-IL)/(EH-EL) ratio of −1.467×10 ⁻⁴ , which satisfied the relationship of −6.0×10 ⁻⁴ or more.

<Measurement of transmittance and phase difference>
The transmittance (wavelength: 405 nm) and phase difference (wavelength: 405 nm) were measured for the surface of the pattern-forming thin film 30 of the mask blank 10 of Example 3. As a result, the transmittance of the pattern-forming thin film 30 in Example 3 was 30.9%, and the phase difference was 143 degrees.

<Transfer Mask 100 and Its Manufacturing Method>
Using the mask blank 10 of Example 3 manufactured as described above, a transfer mask 100 was manufactured in the same manner as in Example 1, to obtain a transfer mask 100 of Example 3 in which a thin film pattern 30a for pattern formation having a hole diameter of 1.5 μm in the transfer pattern formation region and a light-shielding band consisting of a laminated structure of the thin film pattern 30a for pattern formation and an etching mask film pattern 40b were formed on the light-transmitting substrate 20.

<Cross-sectional shape of transfer mask 100>
The cross section of the resulting transfer mask 100 was observed with a scanning electron microscope.
The pattern-forming thin film pattern 30a of the transfer mask 100 of Example 3 had a cross-sectional shape that was nearly vertical. Therefore, the pattern-forming thin film pattern 30a formed on the transfer mask 100 of Example 3 had a cross-sectional shape that could fully exhibit the phase shift effect.

From the above, it can be said that when the transfer mask 100 of Example 3 is set on the mask stage of an exposure device and exposed and transferred to a resist film on a substrate for a display device, a transfer pattern including a fine pattern of less than 2.0 μm can be transferred with high precision.

<Light resistance>
A sample was prepared by forming the thin film 30 for pattern formation used in the mask blank 10 of Example 3 on a light-transmitting substrate 20. The thin film 30 for pattern formation of the sample of Example 3 was irradiated with light from a metal halide light source containing ultraviolet light with a wavelength of 405 nm to a total irradiation dose of 10 kJ/ ^cm2 . The transmittance was measured before and after irradiation with a predetermined amount of ultraviolet light, and the change in transmittance [(transmittance after ultraviolet light irradiation) - (transmittance before ultraviolet light irradiation)] was calculated to evaluate the light resistance of the thin film 30 for pattern formation. The transmittance was measured using a spectrophotometer.

As shown in FIG. 7, in Example 3, the change in transmittance before and after UV irradiation was a favorable 0.74%. From the above, it was found that the thin film for pattern formation in Example 3 is a film with sufficient light resistance for practical use.

From the above, it has become clear that the thin film for pattern formation of Example 3 is an unprecedentedly excellent product that satisfies the requirements for high light resistance to exposure light including wavelengths in the ultraviolet region while also satisfying the desired optical properties (transmittance, phase difference).

(Comparative Example 1)
The mask blank 10 of Comparative Example 1 was produced in the same manner as the mask blank 10 of Example 1, except that the thin film 30 for pattern formation was prepared as follows.
The method for forming the thin film 30 for pattern formation in Comparative Example 1 is as follows.
In order to form a pattern-forming thin film 30 on the main surface of the light-transmitting substrate 20, a mixed gas consisting of argon (Ar) gas and nitrogen (N ₂ ) gas was first introduced into the first chamber. Then, a titanium silicide nitride containing titanium, silicon, and nitrogen was deposited on the main surface of the light-transmitting substrate 20 by reactive sputtering using a first sputtering target containing titanium and silicon. In this manner, a pattern-forming thin film 30 (Ti:Si:N:O=11.1:34.0:50.7:4.2 atomic % ratio) having a thickness of 118 nm and made of titanium silicide nitride was formed.
Thereafter, in the same manner as in the first embodiment, an etching mask film 40 was formed.

Then, on the main surface of another synthetic quartz substrate, another thin film for pattern formation was formed under the same film formation conditions as those of Comparative Example 1. Next, for a sample cut to a predetermined size from the thin film for pattern formation on this other synthetic quartz substrate, X-ray absorption fine structure analysis was performed by X-ray absorption spectroscopy (total electron yield method, fluorescence yield method) in the same manner as in Example 1, and an X-ray absorption spectrum was obtained.
As shown in FIG. 5 , in the X-ray absorption spectrum originating from Ar obtained by the fluorescence yield method of Comparative Example 1, the X-ray absorption coefficient at the incident X-ray energy EH of 3210 eV is larger than the X-ray absorption coefficient at the incident X-ray energy EL of 3180 eV, and it was confirmed that Ar is present in at least some region of the thin film 30 in the thickness direction.
As can be seen from the values shown in FIG. 6, the X-ray absorption spectrum of the surface layer of the thin film 30 in Comparative Example 1 had an (IH-IL)/(EH-EL) ratio of −1.233×10 ⁻³ , which did not satisfy the relationship of −6.0×10 ⁻⁴ or more.

<Measurement of transmittance and phase difference>
The transmittance (wavelength: 405 nm) and phase difference (wavelength: 405 nm) were measured for the surface of the thin film for pattern formation 30 of the mask blank 10 of Comparative Example 1. As a result, the transmittance of the thin film for pattern formation 30 in Comparative Example 1 was 31.7%, and the phase difference was 154 degrees.

<Transfer Mask 100 and Its Manufacturing Method>
Using the mask blank 10 of Comparative Example 1 manufactured as described above, a transfer mask 100 was manufactured in the same manner as in Example 1, and a transfer mask 100 of Comparative Example 1 was obtained, in which a thin film pattern 30a for pattern formation having a hole diameter of 1.5 μm in the transfer pattern formation region and a light-shielding band consisting of a laminated structure of the thin film pattern 30a for pattern formation and the etching mask film pattern 40b were formed on the light-transmitting substrate 20.

<Cross-sectional shape of transfer mask 100>
The cross section of the resulting transfer mask 100 was observed with a scanning electron microscope.
The pattern-forming thin film pattern 30a of the transfer mask 100 of Comparative Example 1 had a cross-sectional shape that was nearly vertical. Therefore, the pattern-forming thin film pattern 30a formed on the transfer mask 100 of Comparative Example 1 had a cross-sectional shape that could fully exert the phase shift effect.

From the above, it can be said that when the transfer mask 100 of Comparative Example 1 is set on the mask stage of an exposure device and exposed and transferred to a resist film on a substrate for a display device, a transfer pattern including a fine pattern of less than 2.0 μm can be transferred with high precision.

<Light resistance>
A sample was prepared by forming the thin film 30 for pattern formation used in the mask blank 10 of Comparative Example 1 on a light-transmitting substrate 20. The thin film 30 for pattern formation of the sample of Comparative Example 1 was irradiated with light from a metal halide light source containing ultraviolet light with a wavelength of 405 nm to a total irradiation dose of 10 kJ/ ^cm2 . The transmittance was measured before and after irradiation with a predetermined amount of ultraviolet light, and the change in transmittance [(transmittance after ultraviolet light irradiation) - (transmittance before ultraviolet light irradiation)] was calculated to evaluate the light resistance of the thin film 30 for pattern formation. The transmittance was measured using a spectrophotometer.

As shown in Figure 7, in Comparative Example 1, the change in transmittance before and after UV irradiation was 2.32%, which was outside the allowable range. From the above, it was found that the thin film for pattern formation in Comparative Example 1 does not have sufficient light resistance for practical use.

(Comparative Example 2)
The mask blank 10 of Comparative Example 2 was produced in the same manner as the mask blank 10 of Example 1, except that the thin film 30 for pattern formation was prepared as follows.
The method for forming the thin film 30 for pattern formation in Comparative Example 2 is as follows.
In order to form a pattern-forming thin film 30 on the main surface of the light-transmitting substrate 20, a mixed gas consisting of argon (Ar) gas and nitrogen (N ₂ ) gas was first introduced into the first chamber. Then, a titanium silicide nitride containing titanium, silicon, and nitrogen was deposited on the main surface of the light-transmitting substrate 20 by reactive sputtering using a first sputtering target containing titanium and silicon. In this manner, a pattern-forming thin film 30 (Ti:Si:N:O=11.7:35.0:52.0:1.3 atomic % ratio) having a thickness of 117 nm and made of titanium silicide nitride was formed.
Thereafter, in the same manner as in the first embodiment, an etching mask film 40 was formed.

Then, on the main surface of another synthetic quartz substrate, another thin film for pattern formation was formed under the same film formation conditions as those of Comparative Example 2. Next, for a sample cut to a predetermined size from the thin film for pattern formation on this other synthetic quartz substrate, X-ray absorption fine structure analysis was performed by X-ray absorption spectroscopy (total electron yield method, fluorescence yield method) in the same manner as in Example 1, and an X-ray absorption spectrum was obtained.
As shown in FIG. 5 , in the X-ray absorption spectrum derived from Ar obtained by the fluorescence yield method of Comparative Example 2, the X-ray absorption coefficient at the incident X-ray energy EH of 3210 eV is larger than the X-ray absorption coefficient at the incident X-ray energy EL of 3180 eV, and it was confirmed that Ar is present in at least some region of the thin film 30 in the thickness direction.
As can be seen from the values shown in FIG. 6, the X-ray absorption spectrum of the surface layer of the thin film 30 in Comparative Example 2 had an (IH-IL)/(EH-EL) ratio of −6.133×10 ⁻⁴ , which did not satisfy the relationship of −6.0×10 ⁻⁴ or more.

<Measurement of transmittance and phase difference>
The transmittance (wavelength: 405 nm) and phase difference (wavelength: 405 nm) were measured for the surface of the thin film for pattern formation 30 of the mask blank 10 of Comparative Example 2. As a result, the transmittance of the thin film for pattern formation 30 in Comparative Example 2 was 33.5%, and the phase difference was 144 degrees.

<Transfer Mask 100 and Its Manufacturing Method>
Using the mask blank 10 of Comparative Example 2 manufactured as described above, a transfer mask 100 was manufactured in the same manner as in Example 1, and a transfer mask 100 of Comparative Example 2 was obtained in which a thin film pattern 30a for pattern formation having a hole diameter of 1.5 μm in the transfer pattern formation region and a light-shielding band consisting of a laminated structure of the thin film pattern 30a for pattern formation and the etching mask film pattern 40b were formed on the light-transmitting substrate 20.

<Cross-sectional shape of transfer mask 100>
The cross section of the resulting transfer mask 100 was observed with a scanning electron microscope.
The pattern-forming thin film pattern 30a of the transfer mask 100 of Comparative Example 2 had a cross-sectional shape that was nearly vertical. Therefore, the pattern-forming thin film pattern 30a formed on the transfer mask 100 of Comparative Example 2 had a cross-sectional shape that could fully exhibit the phase shift effect.

From the above, it can be said that when the transfer mask 100 of Comparative Example 2 is set on the mask stage of an exposure device and exposed and transferred to a resist film on a substrate for a display device, a transfer pattern including a fine pattern of less than 2.0 μm can be transferred with high precision.

<Light resistance>
A sample was prepared by forming the thin film 30 for pattern formation used in the mask blank 10 of Comparative Example 2 on a light-transmitting substrate 20. The thin film 30 for pattern formation of the sample of Comparative Example 1 was irradiated with light from a metal halide light source containing ultraviolet light with a wavelength of 405 nm to a total irradiation dose of 10 kJ/ ^cm2 . The transmittance was measured before and after irradiation with a predetermined amount of ultraviolet light, and the change in transmittance [(transmittance after ultraviolet light irradiation) - (transmittance before ultraviolet light irradiation)] was calculated to evaluate the light resistance of the thin film 30 for pattern formation. The transmittance was measured using a spectrophotometer.

As shown in Figure 7, in Comparative Example 2, the change in transmittance before and after UV irradiation was 2.06%, which was outside the allowable range. From the above, it was found that the thin film for pattern formation in Comparative Example 2 does not have sufficient light resistance for practical use.

In the above-mentioned embodiment, examples of a transfer mask 100 for manufacturing a display device and a mask blank 10 for manufacturing a transfer mask 100 for manufacturing a display device have been described, but the present invention is not limited to this. The mask blank 10 and/or transfer mask 100 of the present invention can also be applied to semiconductor device manufacturing, MEMS manufacturing, printed circuit board manufacturing, and the like. The present invention can also be applied to a binary mask blank having a light-shielding film as a thin film 30 for pattern formation, and a binary mask having a light-shielding film pattern.

In the above embodiment, the size of the light-transmitting substrate 20 is 1214 size (1220 mm x 1400 mm x 13 mm), but this is not limited to this. In the case of a mask blank 10 for manufacturing a display device, a large size light-transmitting substrate 20 is used, and the size of the light-transmitting substrate 20 is such that the length of one side of the main surface is 300 mm or more. The size of the light-transmitting substrate 20 used in the mask blank 10 for manufacturing a display device is, for example, 330 mm x 450 mm or more and 2280 mm x 3130 mm or less.

In addition, in the case of a mask blank 10 for manufacturing semiconductor devices, MEMS, or printed circuit boards, a small size light-transmitting substrate 20 is used, and the size of the light-transmitting substrate 20 is 9 inches or less on one side. The size of the light-transmitting substrate 20 used in the mask blank 10 for the above-mentioned applications is, for example, 63.1 mm x 63.1 mm or more and 228.6 mm x 228.6 mm or less. Usually, a 6025 size (152 mm x 152 mm) or a 5009 size (126.6 mm x 126.6 mm) is used as a light-transmitting substrate 20 for a transfer mask 100 for manufacturing semiconductor devices and MEMS. Also, usually, a 7012 size (177.4 mm x 177.4 mm) or a 9012 size (228.6 mm x 228.6 mm) is used as a light-transmitting substrate 20 for a transfer mask 100 for manufacturing printed circuit boards.

REFERENCE SIGNS LIST 10 mask blank 20 light-transmitting substrate 30 thin film for pattern formation 30a thin film pattern 40 etching mask film 40a first etching mask film pattern 40b second etching mask film pattern 50 first resist film pattern 60 second resist film pattern 100 transfer mask

Claims (14)

A mask blank comprising a thin film for pattern formation on a light-transmitting substrate,
the thin film contains a transition metal and silicon;
The X-ray absorption spectrum of the surface layer of the thin film obtained by the total electron yield method is
IL is the X-ray absorption coefficient when the incident X-ray energy EL is 3180 eV,
When the X-ray absorption coefficient at the incident X-ray energy EH of 3210 eV is IH,
A mask blank, characterized in that (IH-IL)/(EH-EL) is -6.0×10 ^-4 or more. The mask blank according to claim 1, characterized in that the X-ray absorption spectrum of the thin film obtained by the fluorescence yield method has a larger X-ray absorption coefficient at an incident X-ray energy EH of 3210 eV than at an incident X-ray energy EL of 3180 eV. The mask blank according to claim 1, characterized in that the thin film contains at least titanium as the transition metal. The mask blank according to claim 1, characterized in that the thin film further contains nitrogen. The mask blank according to claim 1, characterized in that the ratio of the transition metal content to the total content of the transition metal and silicon in the thin film is 0.05 or more. The mask blank according to claim 1, characterized in that an etching mask film having a different etching selectivity with respect to the thin film is provided on the thin film. The mask blank according to claim 6, characterized in that the etching mask film contains chromium. A transfer mask comprising a thin film having a transfer pattern on a light-transmitting substrate,
the thin film contains a transition metal and silicon;
The X-ray absorption spectrum of the surface layer of the thin film obtained by the total electron yield method is
IL is the X-ray absorption coefficient when the incident X-ray energy EL is 3180 eV,
When the X-ray absorption coefficient at the incident X-ray energy EH of 3210 eV is IH,
A transfer mask, wherein (IH-IL)/(EH-EL) is -6.0×10 ^-4 or more. The transfer mask according to claim 8, characterized in that the X-ray absorption spectrum of the thin film obtained by the fluorescence yield method has a larger X-ray absorption coefficient at an incident X-ray energy EH of 3210 eV than at an incident X-ray energy EL of 3180 eV. The transfer mask according to claim 8, characterized in that the thin film contains at least titanium as the transition metal. The transfer mask according to claim 8, characterized in that the thin film further contains nitrogen. The transfer mask according to claim 8, characterized in that the ratio of the transition metal content to the total content of the transition metal and silicon in the thin film is 0.05 or more. A step of preparing a mask blank according to claim 6 or 7;
forming a resist film having a transfer pattern on the etching mask film;
performing wet etching using the resist film as a mask to form a transfer pattern on the etching mask film;
performing wet etching using the etching mask film on which the transfer pattern is formed as a mask to form a transfer pattern on the thin film;
2. A method for producing a transfer mask comprising the steps of: A step of placing the transfer mask according to any one of claims 8 to 12 on a mask stage of an exposure tool;
a step of irradiating the transfer mask with exposure light to transfer a transfer pattern onto a resist film provided on a substrate for a display device;
A method for manufacturing a display device comprising the steps of:

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