JP7254470B2 - Phase shift mask blank, phase shift mask manufacturing method, and display device manufacturing method - Google Patents

Description

The present invention relates to a phase shift mask blank, a phase shift mask manufacturing method using the same, and a display device manufacturing method.

2. Description of the Related Art In recent years, display devices such as FPDs (Flat Panel Displays) typified by LCDs (Liquid Crystal Displays) are rapidly increasing in screen size and viewing angle, as well as high definition and high speed display. One of the factors required for achieving high-definition and high-speed display is the fabrication of electronic circuit patterns such as fine elements and wiring with high dimensional accuracy. Photolithography is often used for patterning electronic circuits for display devices. Therefore, there is a need for a phase shift mask for manufacturing display devices, on which fine and highly accurate patterns are formed.

For example, Patent Document 1 discloses a phase-shifting mask blank having a phase-shifting film on a transparent substrate. In this mask blank, the phase shift film has a reflectance of 35% or less and a reflectance of 1% to 40% for compound wavelength exposure light including i-line (365 nm), h-line (405 nm), and g-line (436 nm). A metal silicide compound containing at least one light element substance of oxygen (O), nitrogen (N), and carbon (C) so as to have a transmittance and sharply slope the pattern section when forming the pattern. The metal silicide compound is formed by injecting the reactive gas containing the light element substance and the inert gas at a ratio of 0.5:9.5 to 4:6. ing.

Korea Registered Patent No. 1801101

As a phase shift mask used in recent high-definition (1000 ppi or more) panel production, a phase shift mask with a high transmittance of 15% or more in exposure light is used in order to enable high-resolution pattern transfer. There is a demand for a phase shift mask in which a fine phase shift film pattern with a hole diameter of 6 μm or less and a line width of 4 μm or less is formed. Specifically, there is a demand for a phase shift mask in which a fine phase shift film pattern with a hole diameter of 1.5 μm is formed.
The phase shift mask described above is produced by forming a phase shift film pattern by wet etching using an etching mask film pattern made of a Cr-based material formed on a phase shift film made of a metal silicide compound as a mask. .
The cross-sectional shape of the phase shift film pattern can be controlled to a nearly vertical shape by performing an etching process with an etching time (overetching time) longer than the just etching time and side-etching the phase shift film pattern. Sometimes. However, the side etching increases the hole diameter and line width formed in the phase shift film. Therefore, when a phase shift film pattern having a fine hole diameter and line width as described above is to be formed, the amount of overetching of the phase shift film (the amount of side etching) must be considered. The hole diameter or line width of the etching mask film pattern formed on the film and the hole diameter or line width drawn on the resist film must be made smaller. There is a limit to pattern formation in the photolithography technology using the current drawing device/developing device. Therefore, when forming the required fine phase shift film pattern on the phase shift film by wet etching, the range within 120% of the just etching time (100% just etching time + 20% over etching time. Hereinafter, it is desirable to perform the etching process with an over-etching time of 120% or less. However, with such a short over-etching time, there is a problem that a phase shift mask blank having a good cross-sectional shape of the phase shift film pattern cannot be realized. Moreover, even when a phase shift film pattern is formed on a phase shift film using a resist pattern as a mask without using an etching mask film, the same problem occurs.

SUMMARY OF THE INVENTION Accordingly, the present invention has been made to solve the above-mentioned problems. To provide a phase shift mask blank capable of forming a phase shift film pattern having a cross-sectional shape with a good phase shift effect.

In order to solve these problems, the present inventors diligently studied a method for making the cross-sectional shape of the edge portion of the phase shift film pattern vertical. In order to form a phase shift film having a high transmittance as described above, it is conceivable to contain oxygen at a certain ratio or more. In addition, from the viewpoint of reducing the film thickness for obtaining the retardation, it is conceivable to contain nitrogen at a certain ratio or more. However, if the phase shift film is simply made to contain oxygen and nitrogen at a certain ratio or more, the cross section of the phase shift film pattern is inclined, and a sufficient phase shift effect cannot be obtained. Therefore, the present inventors conducted experiments and considerations on the content of light element components including oxygen and nitrogen in the phase shift film pattern and the ratio of oxygen and nitrogen in the depth direction. The total content of the components is 50 atomic % or more, and the phase shift film has a composition gradient in which oxygen decreases and nitrogen increases from the substrate side to the surface side. When forming a phase shift film pattern by wet etching, even with a small overetching time of 120% or less, it was found that a phase shift film pattern having a cross-sectional shape with a good phase shift effect can be formed. The present invention was made as a result of the above earnest studies, and has the following configurations.

(Configuration 1) A phase shift mask blank having a phase shift film on a transparent substrate,
The phase shift film contains a transition metal, silicon, oxygen, and nitrogen, and the total content of light element components containing oxygen and nitrogen is 50 atomic % or more,
In the phase shift film, the proportion of oxygen increases stepwise and/or continuously in the depth direction, and the proportion of nitrogen decreases stepwise and/or continuously in the depth direction. A phase shift mask blank characterized by:

(Configuration 2) Configuration 1, wherein the phase shift film has a phase difference of 160° or more and 200° or less with respect to the exposure light and a transmittance of 15% or more and 80% or less. phase shift mask blank.

(Structure 3) The phase shift mask blank according to structure 1 or 2, wherein the phase shift film is composed of a plurality of layers.
(Structure 4) The phase shift mask blank according to structure 1 or 2, wherein the phase shift film is composed of a single layer.

(Configuration 5) Any one of Configurations 1 to 4, wherein an etching mask film made of a material having etching resistance to an etchant for etching the phase shift film is provided on the phase shift film. Phase shift mask blank as described.

(Structure 6) The phase shift mask blank according to structure 5, wherein the phase shift film has a content ratio of oxygen to silicon at the interface with the etching mask film of 0.5 or more and 2.0 or less.

(Structure 7) A phase shift mask blank according to structure 5 or 6, wherein the etching mask film is made of a chromium-based material.

(Structure 8) A step of preparing the phase shift mask blank according to any one of Structures 1 to 4;
forming a resist film on the phase shift mask blank;
A resist film pattern is formed by drawing and developing a desired pattern on the resist film, and the phase shift film is formed on the transparent substrate by wet etching using the resist film pattern as a mask. and forming a pattern.

(Structure 9) preparing the phase shift mask blank according to any one of structures 5 to 7;
forming a resist film on the phase shift mask blank;
A resist film pattern is formed by drawing and developing a desired pattern on the resist film, and using the resist film pattern as a mask, the etching mask film is patterned by wet etching to form an etching mask film pattern. process and
and forming a phase shift film pattern on the transparent substrate by wet etching the phase shift film using the etching mask film pattern as a mask.

(Structure 10) Using a phase shift mask manufactured using the phase shift mask blank according to any one of structures 1 to 7, or manufactured by the phase shift mask manufacturing method according to structure 8 or 9 A method of manufacturing a display device, comprising a step of exposing and transferring a transfer pattern onto a resist film on the display device using a phase shift mask.

According to the phase shift mask blank according to the present invention, when forming the required fine phase shift film pattern by wet etching, even with a small overetching time of 120% or less, a cross section with a good phase shift effect A phase shift mask blank can be obtained on which a phase shift film pattern having a shape can be formed.

Moreover, according to the method of manufacturing a phase shift mask according to the present invention, a phase shift mask is manufactured using the phase shift mask blank described above. Therefore, a phase shift mask having a phase shift film pattern capable of exhibiting a sufficient phase shift effect can be manufactured. This phase shift mask can cope with the miniaturization of line-and-space patterns and contact holes.

Further, according to the method of manufacturing a display device according to the present invention, a phase shift mask manufactured using the phase shift mask blank described above or a phase shift mask obtained by the method of manufacturing a phase shift mask described above is used for display. Manufacture equipment. Therefore, a display device having fine line-and-space patterns and contact holes can be manufactured.

1 is a schematic diagram showing a film configuration of a phase shift mask blank according to Embodiment 1; FIG. FIG. 10 is a schematic diagram showing a film configuration of a phase shift mask blank according to a second embodiment; FIG. 10 is a schematic diagram showing a manufacturing process of a phase shift mask according to a third embodiment; FIG. 11 is a schematic diagram showing a manufacturing process of a phase shift mask according to a fourth embodiment; FIG. 3 is a diagram showing the composition analysis results in the depth direction for the phase shift mask blank of Example 1; 2 is a diagram showing the O/Si ratio (content ratio of oxygen to silicon) in the depth direction at the interface between the phase shift film and the etching mask film of the phase shift mask blanks of Examples 1 and 2 and Comparative Example 1. FIG. 4 is a cross-sectional photograph of the phase shift mask of Example 1. FIG. 4 is a cross-sectional photograph of the phase shift mask of Example 2. FIG. FIG. 10 is a diagram showing the composition analysis results in the depth direction for the phase shift mask blank of Comparative Example 1; 4 is a cross-sectional photograph of a phase shift mask of Comparative Example 1. FIG.

Embodiment 1.2.
In Embodiments 1 and 2, phase shift mask blanks will be described. The phase shift mask blank of Embodiment 1 is obtained by wet-etching the phase shift film using an etching mask film pattern in which a desired pattern is formed on the etching mask film as a mask. It is an original plate for forming a mask. Further, the phase shift mask blank of the second embodiment is obtained by wet-etching the phase shift film using a resist film pattern in which a desired pattern is formed on the resist film as a mask. It is an original plate for forming a film.

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

The transparent substrate 20 is transparent to exposure light. The transparent substrate 20 has a transmittance of 85% or more, preferably 90% or more, with respect to exposure light, assuming that there is no surface reflection loss. The transparent substrate 20 is made of a material containing silicon and oxygen, and may be made of a glass material such as synthetic quartz glass, quartz glass, aluminosilicate glass, soda lime glass, low thermal expansion glass (SiO ₂ —TiO ₂ glass, etc.). can be done. When the transparent substrate 20 is made of low thermal expansion glass, it is possible to suppress the positional change of the phase shift film pattern due to the thermal deformation of the transparent substrate 20 . The transparent substrate 20 for a phase shift mask blank used for display devices is generally a rectangular substrate with a short side length of 300 mm or more. The present invention can stably transfer a fine phase shift film pattern of, for example, less than 2.0 μm formed on a transparent substrate even if the short side of the transparent substrate has a large size of 300 mm or more. It is a phase shift mask blank that can provide a phase shift mask that can be used.

The phase shift film 30 is composed of a transition metal silicide material containing transition metal, silicon, oxygen and nitrogen. Molybdenum (Mo), tantalum (Ta), tungsten (W), titanium (Ti), zirconium (Zr) and the like are suitable as transition metals. In the transition metal silicide-based material, oxygen, which is a light element component, has the effect of lowering the extinction coefficient compared to nitrogen, which is also a light element component. Nitrogen) can be reduced, and the reflectance of the front and back surfaces of the phase shift film can be effectively reduced. In the above transition metal silicide-based material, 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. It can be made thin. Further, the total content of light element components including oxygen and nitrogen contained in the phase shift film 30 is preferably 50 atomic % or more. More preferably, it is 50 atomic % or more and 70 atomic % or less, and 55 atomic % or more and 65 atomic % or less. Also, the oxygen content is preferably more than 0 atomic % and 40 atomic % or less in terms of defect quality and chemical resistance.
Examples of transition metal silicide-based materials include oxides of transition metal silicides, oxynitrides of transition metal silicides, and oxynitride carbides of transition metal silicides. In addition, when the transition metal silicide-based material is a molybdenum silicide-based material (MoSi-based material), a zirconium silicide-based material (ZrSi-based material), or a molybdenum zirconium silicide-based material (MoZrSi-based material), an excellent pattern cross section can be obtained by wet etching. It is preferable in that the shape can be easily obtained.
In addition to oxygen and nitrogen described above, the phase shift film 30 may contain carbon and helium for the purpose of reducing film stress and controlling the wet etching rate.
The phase shift film 30 has a function of adjusting the reflectance of light incident from the transparent substrate 20 side (hereinafter sometimes referred to as back surface reflectance), and a function of adjusting the transmittance and phase difference of exposure light. have
The phase shift film 30 can be formed by a sputtering method.

The transmittance of the phase shift film 30 with respect to exposure light satisfies the required value for the phase shift film 30 . The transmittance of the phase shift film 30 is preferably 15% to 80%, more preferably 15% to 65%, with respect to light of a predetermined wavelength (hereinafter referred to as representative wavelength) contained in exposure light. and more preferably 20% to 60%. That is, when the exposure light is compound light including light in the wavelength range of 313 nm or more and 436 nm or less, the phase shift film 30 has the above-described transmittance with respect to the light of the representative wavelengths included in the wavelength range. For example, when the exposure light is compound light including i-line, h-line and g-line, phase shift film 30 has the above-described transmittance for any one of i-line, h-line and g-line.
The transmittance can be measured using a phase shift amount measuring device or the like.

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

The back surface reflectance of the phase shift film 30 is 15% or less, preferably 10% or less, in the wavelength range of 365 nm to 436 nm. Further, when the exposure light includes the j-line, the back surface reflectance of the phase shift film 30 is preferably 20% or less, more preferably 17% or less, with respect to light in the wavelength range from 313 nm to 436 nm. More preferably, it should be 15% or less. Further, the back surface reflectance of the phase shift film 30 is preferably 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 or the like.

In order for the phase shift film 30 to have the above rear surface reflectance and the above phase difference and transmittance, the phase shift film 30 satisfies the above-described range of the total content of light element components, and oxygen content is 20 atomic % or more and 55 atomic % or less. Preferably, the oxygen content is set to 25 atomic % or more and 50 atomic % or less. This phase shift film 30 may be composed of a plurality of layers, or may be composed of a single layer. The phase shift film 30 composed of a single layer is preferable in that an interface is less likely to be formed in the phase shift film 30 and the cross-sectional shape can be easily controlled. On the other hand, the phase shift film 30 composed of a plurality of layers is preferable in terms of ease of film formation.

The etching mask film 40 is arranged on the upper side of the phase shift film 30 and is made of a material having etching resistance to the etchant used to etch the phase shift film 30 . The etching mask film 40 may have a function of blocking transmission of the exposure light, and the film surface reflectance of the phase shift film 30 with respect to light incident from the phase shift film 30 side is 350 nm to 436 nm. The etching mask film 40, which may have the function of reducing the film surface reflectance to 15% or less in the wavelength range, is made of, for example, a chromium-based material. More specifically, the chromium-based material is chromium (Cr), or a material containing chromium (Cr) and at least one of oxygen (O), nitrogen (N), and carbon (C). is mentioned. Alternatively, a material containing chromium (Cr) and at least one of oxygen (O), nitrogen (N), and carbon (C), and further containing fluorine (F) can be used. For example, materials forming the etching mask film 40 include Cr, CrO, CrN, CrF, CrCO, CrCN, CrON, CrCON, and CrCONF.
The etching mask film 40 can be formed by a sputtering method.

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

The etching mask film 40 may be composed of a single film having a uniform composition according to its function, may be composed of a plurality of films having different compositions, or may be composed of different compositions in the thickness direction. It may be composed of a single continuously changing film.

It should be noted that the phase shift mask blank 10 shown in FIG. The present invention can also be applied to a phase shift mask blank comprising

In the phase shift film 30 in the phase shift mask blank 10, the oxygen ratio increases stepwise and/or continuously in the depth direction, and the nitrogen ratio increases stepwise and/or in the depth direction. /or arranged to decrease continuously.
In addition, the magnitude of the slope of the oxygen decrease in the 60% region of the central portion excluding the 20% region of the surface portion and the 20% region of the bottom portion with respect to the total thickness of the phase shift film 30 is A thickness of 4 atomic %/100 nm or more and 10 atomic %/100 nm or less in the depth direction is preferable from the viewpoint of verticalization of the pattern cross section and reduction of rear surface reflection. Note that the 20% region of the surface portion refers to a transition metal (to be described later) from the phase shift film 30 toward the etching mask film 40 when the composition of the phase shift mask blank 10 is analyzed by X-ray photoelectron spectroscopy. Molybdenum in the examples and comparative examples) is 20% of the total thickness of the phase shift film 30 in the depth direction of the phase shift film 30 . Further, the 20% region of the bottom portion is a transition metal (which will be described later) toward the transparent substrate 20 from the phase shift film 30 when the composition of the phase shift mask blank 10 is analyzed by X-ray photoelectron spectroscopy. For example, molybdenum in the comparative example) is 20% of the total thickness of the phase shift film 30 toward the surface of the phase shift film 30 . The gradient of the oxygen concentration is the gradient connecting the top and bottom of the 60% region of the central portion.
In addition, the phase shift mask blank 10 has a phase shift film pattern in order to suppress the deterioration of the cross-sectional shape of the phase shift film pattern due to the etchant permeating the phase shift film 30 at the interface between the phase shift film 30 and the etching mask film 40 . The content ratio of oxygen to silicon at the interface between the shift film 30 and the etching mask film 40 is preferably 0.5 or more and 2.0 or less. This interface is the position where silicon is detected for the first time from the etching mask film 40 toward the phase shift film 30 when the phase shift mask blank 10 is subjected to composition analysis by X-ray photoelectron spectroscopy.

Next, a method of manufacturing the phase shift mask blank 10 of the first and second embodiments will be described. The phase shift mask blank 10 shown in FIG. 1 is manufactured by performing the following phase shift film forming process and etching mask film forming process. The phase shift mask blank 10 shown in FIG. 2 is manufactured by a phase shift film formation process.
Each step will be described in detail below.

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

Next, a phase shift film 30 is formed on the transparent substrate 20 by sputtering.
The phase shift film 30 is formed using a sputtering target containing a transition metal and silicon, which are the main components of the material constituting the phase shift film 30, or a sputtering target containing a transition metal, silicon, oxygen and/or nitrogen. , for example, a sputtering gas atmosphere comprising an inert gas containing at least one selected from the group consisting of helium gas, neon gas, argon gas, krypton gas and xenon gas, or the inert gas, oxygen gas, nitrogen gas, and dioxide The sputtering is performed in a sputtering gas atmosphere consisting of a mixed gas with an active gas selected from the group consisting of carbon gas, nitrogen monoxide gas and nitrogen dioxide gas and containing at least oxygen and nitrogen.

The composition and thickness of the phase shift film 30 are adjusted so that the phase shift film 30 has the above phase difference and transmittance. The composition of the phase shift film 30 can be controlled by the content ratio of the elements constituting the sputtering target (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 phase shift film 30 can be controlled by sputtering power, sputtering time, and the like. Moreover, when the sputtering apparatus is an in-line type sputtering apparatus, the thickness of the phase shift film 30 can also be controlled by the transport speed of the substrate. In this manner, control is performed so that the content of light element components including oxygen and nitrogen in the phase shift film 30 is 50 atomic % or more and 70 atomic % or less.

When the phase shift film 30 is composed of a single film, the above-described film formation process is performed such that the proportion of oxygen increases stepwise and/or continuously in the depth direction, and the proportion of nitrogen increases in the depth direction. This is performed only once while changing the composition and flow rate of the sputtering gas along with the elapsed time of the deposition process so as to decrease stepwise and/or continuously. When the phase shift film 30 is composed of a plurality of films with different compositions, the film formation process described above is performed a plurality of times while changing the composition and flow rate of the sputtering gas for each film formation process. The phase shift film 30 may be deposited using targets having different content ratios of the elements constituting the sputtering target. When the film formation process is performed multiple times, the sputtering power applied to the sputtering target can be reduced.

2. Surface treatment step After forming the phase shift film 30 made of a transition metal silicide material containing a transition metal, silicon, oxygen, and nitrogen, the phase shift film 30 is treated with an etchant due to the presence of transition metal oxides. In order to suppress the permeation, a surface treatment process for adjusting the state of surface oxidation of the phase shift film 30 may be performed.
Examples of the surface treatment process for adjusting the state of surface oxidation of the phase shift film 30 include a method of surface treatment with an acidic aqueous solution, a method of surface treatment with an alkaline aqueous solution, and a method of dry treatment such as ashing. .
After the etching mask film forming step, which will be described later, in the phase shift film 30, the proportion of oxygen increases stepwise and/or continuously in the depth direction, and the proportion of nitrogen increases stepwise and / Or if the content ratio of oxygen to silicon at the interface between the phase shift film 30 and the etching mask film 40 is 0.5 or more and 2.0 or less, what kind of surface treatment process should be performed? The surface treatment process may be performed, or the surface treatment process may not be performed. When the oxygen content in the vicinity of the interface of the phase shift film 30 exceeds 30 atomic %, it is preferable to perform a surface treatment process. If the oxygen content in the vicinity of the interface of the phase shift film 30 is 30 atomic % or less, the surface treatment process may not be performed.
For example, in the method of surface treatment with an acidic aqueous solution and the method of surface treatment with an alkaline aqueous solution, the state of surface oxidation of the phase shift film 30 can be controlled by appropriately adjusting the concentration, temperature, and time of the acidic or alkaline aqueous solution. can be adjusted. As a method of surface treatment with an acidic aqueous solution and a method of surface treatment with an alkaline aqueous solution, a method of immersing a substrate with a phase shift film in which a phase shift film 30 is formed on a transparent substrate 20 is immersed in the aqueous solution, A method of bringing the aqueous solution into contact with the membrane 30 may be used.

3. Etching Mask Film Forming Step After surface treatment for adjusting the state of surface oxidation of the surface of the phase shift film 30 is performed as necessary, an etching mask film 40 is formed on the phase shift film 30 by a sputtering method.
A phase shift mask blank 10 is thus obtained.
The etching mask film 40 is formed using a sputtering target containing chromium or a chromium compound (chromium oxide, chromium nitride, chromium carbide, chromium oxynitride, chromium carbide oxynitride, etc.), for example, helium gas, neon gas, argon. A sputtering gas atmosphere consisting of an inert gas containing at least one selected from the group consisting of gas, krypton gas and xenon gas, or at least one selected from the group consisting of helium gas, neon gas, argon gas, krypton gas and xenon gas. and an active gas containing at least one selected from the group consisting of oxygen gas, nitrogen gas, nitrogen monoxide gas, nitrogen dioxide gas, carbon dioxide gas, hydrocarbon-based gas, and fluorine-based gas It is carried out in a sputter gas atmosphere of Hydrocarbon gases include, for example, methane gas, butane gas, propane gas, and styrene gas.

When the etching mask film 40 is composed of a single film with a uniform composition, the above-described film formation process is performed only once without changing the composition and flow rate of the sputtering gas. When the etching mask film 40 is composed of a plurality of films with different compositions, the film formation process described above is performed a plurality of times while changing the composition and flow rate of the sputtering gas for each film formation process. When the etching mask film 40 is composed of a single film whose composition changes continuously in the thickness direction, the film formation process described above is repeated while changing the composition and flow rate of the sputtering gas with the elapsed time of the film formation process. do it only once.

In this way, the phase shift film 30 is free from oxygen by carrying out the film formation process of the phase shift film 30 and the etching mask film 40 and the surface treatment for adjusting the state of surface oxidation of the surface of the phase shift film 30 as necessary. The proportion of nitrogen increases stepwise and/or continuously in the depth direction, the proportion of nitrogen decreases stepwise and/or continuously in the depth direction, and the phase shift film and the above The phase shift film 30 and the etching mask film 40 can be formed such that the content ratio of oxygen to silicon at the interface with the etching mask film is 0.5 or more and 2.0 or less.

The surface treatment for adjusting the state of surface oxidation of the surface of the phase shift film 30 has been described. By changing to a gas species that is difficult to resist or by adding the above gas species, the oxygen ratio is increased stepwise and/or continuously in the depth direction, and the nitrogen ratio is increased in the depth direction. The content ratio of oxygen to silicon at the interface between the phase shift film and the etching mask film may be 0.5 or more and 2.0 or less.

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

The phase shift mask blank 10 of Embodiment 1 is a phase shift mask blank in which an etching mask film 40 is formed on a phase shift film 30. In the phase shift film 30, the proportion of oxygen increases in the depth direction. , and the proportion of nitrogen decreases stepwise and/or continuously in the depth direction. Further, the phase shift mask blank 10 of Embodiment 2 is a phase shift mask blank on which a phase shift film is formed. It is configured such that the proportion of nitrogen increases stepwise and/or continuously in the depth direction.

Further, in the phase shift mask blank 10 of Embodiment 1, the oxygen ratio in the phase shift film 30 increases stepwise and/or continuously in the depth direction, and the nitrogen ratio increases in the depth direction. so that the content ratio of oxygen to silicon at the interface between the phase shift film and the etching mask film is 0.5 or more and 2.0 or less, A phase shift film 30 and an etching mask film 40 are formed.
As a result, when forming the required fine phase shift film pattern by wet etching, even with a small overetching time of 120% or less, a phase shift film pattern having a cross-sectional shape with a good phase shift effect can be formed. a phase-shift mask can be obtained.

In addition, in the phase shift mask, if the etching mask film pattern remains on the phase shift film pattern, the influence of reflection from the pellicle attached to the phase shift mask and the display device substrate can be suppressed.
Further, the phase shift mask blanks 10 of the first and second embodiments have a good cross-sectional shape, and a phase shift film pattern with high transmittance can be formed by wet etching. Therefore, it is possible to obtain a phase shift mask blank capable of manufacturing a phase shift mask capable of accurately transferring a high-definition phase shift film pattern.

Embodiment 3.4.
In Embodiments 3 and 4, a method for manufacturing a phase shift mask will be described.

FIG. 3 is a schematic diagram showing a method of manufacturing a phase shift mask according to the third embodiment. FIG. 4 is a schematic diagram showing a method of manufacturing a phase shift mask according to the fourth embodiment.
The method of manufacturing a phase shift mask shown in FIG. 3 is a method of manufacturing a phase shift mask using the phase shift mask blank 10 shown in FIG. Then, a desired pattern is drawn and developed on the resist film to form a resist film pattern 50 (first resist film pattern forming step), and using the resist film pattern 50 as a mask, an etching mask film is formed by wet etching. 40 to form an etching mask film pattern 40a (first etching mask film pattern forming step), and using the etching mask film pattern 40a as a mask, the phase shift film 30 is wet etched on the transparent substrate 20 and a step of forming the phase shift film pattern 30a (phase shift film pattern forming step). The method further includes a second resist film pattern forming step and a second etching mask film pattern forming step.

The method of manufacturing a phase shift mask shown in FIG. 4 is a method of manufacturing a phase shift mask using the phase shift mask blank 10 shown in FIG. Then, a desired pattern is drawn and developed on the resist film to form a resist film pattern 50 (first resist film pattern forming step), and the phase shift film 30 is wetted using the resist film pattern 50 as a mask. and a step of patterning by etching to form a phase shift film pattern 30a on the transparent substrate 20 (phase shift film pattern forming step).
Each step of the manufacturing process of the phase shift mask according to the third and fourth embodiments will be described in detail below.

Manufacturing process of the phase shift mask according to the third embodiment 1. First Resist Film Pattern Forming Step In the first resist film pattern forming step, first, a resist film is formed on the etching mask film 40 of the phase shift mask blank 10 of the first embodiment. The resist film material to be used is not particularly limited. For example, any material may be used as long as it is sensitive to laser light having a wavelength selected from the wavelength range of 350 nm to 436 nm, which will be described later. Moreover, the resist film may be either positive type or negative type.
After that, a desired pattern is drawn on the resist film using a laser beam having a wavelength selected from a wavelength range of 350 nm to 436 nm. The pattern drawn on the resist film is the pattern formed on the phase shift film 30 . Patterns drawn on the resist film include line-and-space patterns and hole patterns.
Thereafter, the resist film is developed with a predetermined developer to form a first resist film pattern 50 on the etching mask film 40 as shown in FIG. 3(a).

2. First Etching Mask Film Pattern Forming Step In the first etching mask film pattern forming step, first, the etching mask film 40 is etched using the first resist film pattern 50 as a mask to form a first etching mask film pattern 40a. to form The etching mask film 40 is made of a chromium-based material containing chromium (Cr). The etchant for etching the etching mask film 40 is not particularly limited as long as it can selectively etch the etching mask film 40 . Specifically, an etchant containing ceric ammonium nitrate and perchloric acid is mentioned.
Thereafter, the first resist film pattern 50 is removed using a resist remover or by ashing as shown in FIG. 3(b). In some cases, the next phase shift film pattern forming step may be performed without removing the first resist film pattern 50 .

3. Phase Shift Film Pattern Forming Step In the first phase shift film pattern forming step, the phase shift film 30 is etched using the first etching mask film pattern 40a as a mask, and the phase shift film 30 is formed as shown in FIG. 3(c). A shift film pattern 30a is formed. The phase shift film pattern 30a includes a line-and-space pattern and a hole pattern. The etchant for etching the phase shift film 30 is not particularly limited as long as it can selectively etch the phase shift film 30 . For example, an etchant containing ammonium fluoride, phosphoric acid and hydrogen peroxide, and an etchant containing ammonium hydrogen fluoride and hydrogen peroxide can be used. This etching process is performed with an over-etching time within 120% of the just etching time.

4. Second Resist Film Pattern Forming Step In the second resist film pattern forming step, first, a resist film is formed to cover the first etching mask film pattern 40a. The resist film material to be used is not particularly limited. For example, any material may be used as long as it is sensitive to laser light having a wavelength selected from the wavelength range of 350 nm to 436 nm, which will be described later. Moreover, the resist film may be either positive type or negative type.
After that, a desired pattern is drawn on the resist film using a laser beam having a wavelength selected from a wavelength range of 350 nm to 436 nm. The pattern to be drawn on the resist film includes a light shielding band pattern for shielding the peripheral region of the region where the pattern is formed on the phase shift film 30, a light shielding band pattern for shielding the central portion of the phase shift film pattern, and the like. Depending on the transmittance of the phase shift film 30 with respect to the exposure light, the pattern drawn on the resist film may be a pattern without a light shielding band pattern for shielding the central portion of the phase shift film pattern 30a.
Thereafter, the resist film is developed with a predetermined developer to form a second resist film pattern 60 on the first etching mask film pattern 40a, as shown in FIG. 3(d).

5. Second etching mask film pattern forming process In the second etching mask film pattern forming process, the first etching mask film pattern 40a is etched using the second resist film pattern 60 as a mask, and the pattern shown in FIG. As shown, a second etch mask film pattern 40b is formed. The first etching mask film pattern 40a is formed of a chromium-based material containing chromium (Cr). The etchant 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 etchant containing ceric ammonium nitrate and perchloric acid may be used.
After that, the second resist film pattern 60 is stripped using a resist stripper or by ashing.
Thus, a phase shift mask 100 is obtained.
In the above description, the case where the etching mask film 40 has the function of blocking the transmission of the exposure light has been described, but the case where the etching mask film 40 simply has the function of a hard mask when the phase shift film 30 is etched. In the above description, the second resist film pattern forming step and the second etching mask film pattern forming step are not performed, and the first etching mask film pattern is removed after the phase shift film pattern forming step. , to fabricate the phase shift mask 100 .

According to the phase shift mask manufacturing method of the third embodiment, since the phase shift mask blank of the first embodiment is used, a phase shift film pattern having a good cross-sectional shape can be formed. Therefore, it is possible to manufacture a phase shift mask capable of accurately transferring a fine phase shift film pattern. A phase shift mask manufactured in this manner can be applied to miniaturization of line-and-space patterns and contact holes.

Manufacturing process of the phase shift mask according to the fourth embodiment 1. Resist Film Pattern Forming Step In the resist film pattern forming step, first, a resist film is formed on the phase shift film 30 of the phase shift mask blank 10 of the second embodiment. The resist film materials used are the same as those described in the third embodiment. In addition, before forming the resist film, the phase shift film 30 may be subjected to a surface modification treatment in order to improve the adhesion to the phase shift film 30, if necessary. After forming a resist film in the same manner as described above, a desired pattern is drawn on the resist film using a laser beam having a wavelength selected from the wavelength range of 350 nm to 436 nm. Thereafter, the resist film is developed with a predetermined developer to form a resist film pattern 50 on the phase shift film 30 as shown in FIG. 4(a).
2. Phase Shift Film Pattern Forming Step In the phase shift film pattern forming step, the phase shift film 30 is etched using the resist film pattern as a mask to form a phase shift film pattern 30a as shown in FIG. 4(b). The etchant for etching the phase shift film pattern 30a and the phase shift film 30 is the same as that described in the third embodiment.
Thereafter, the resist film pattern 50 is removed using a resist remover or by ashing (FIG. 4(c)).
Thus, a phase shift mask 100 is obtained.
According to the phase shift mask manufacturing method of the fourth embodiment, since the phase shift mask blank of the second embodiment is used, a phase shift film pattern having a good cross-sectional shape can be formed. Therefore, it is possible to manufacture a phase shift mask capable of accurately transferring a fine phase shift film pattern. A phase shift mask manufactured in this manner can be applied to miniaturization of line-and-space patterns and contact holes.

Embodiment 5.
In Embodiment 5, a method for manufacturing a display device will be described. The display device uses the phase shift mask 100 manufactured using the phase shift mask blank 10 described above, or uses the phase shift mask 100 manufactured by the manufacturing method of the phase shift mask 100 described above (mask mounting process). ) and a step of exposing and transferring a transfer pattern onto a resist film on the display device (pattern transfer step).
Each step will be described in detail below.

1. Mounting Step In the mounting step, the phase shift mask manufactured in Embodiment 3 is mounted on the mask stage of the exposure apparatus. Here, the phase shift mask is arranged so as to face the resist film formed on the display device substrate via the projection optical system of the exposure device.

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

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

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

After that, the synthetic quartz glass substrate was placed on a tray (not shown) with the main surface facing downward, and carried into the chamber of an in-line sputtering apparatus.
In order to form the phase shift film 30 on the main surface of the transparent substrate 20, first, an inert gas composed of argon (Ar) gas and nitrogen (N ₂ ) gas is introduced into the first chamber with a predetermined degree of vacuum. A mixed gas (Ar: 40 sccm, N ₂ : 34 sccm, NO: 34.5 sccm) of an active gas and a reactive gas of nitrogen monoxide (NO) was introduced. That is, the flow rate ratio of the reactive gas and the inert gas is reactive gas:inert gas=0.47:1. Then, a first sputtering target containing molybdenum and silicon (molybdenum:silicon=1:4) is applied with a sputtering power of 7.0 kW to deposit molybdenum, silicon and oxygen on the main surface of transparent substrate 20 by reactive sputtering. and nitrogen-containing molybdenum silicide oxynitride. During this process, the above mixed gas is supplied from a gas supply pipe installed on the upstream side of the sputtering target in the transport direction of the substrate, thereby oxidizing the molybdenum silicide deposited on the main surface of the transparent substrate 20. In the nitride, the proportion of oxygen contained was gradually decreased, while the proportion of nitrogen was gradually increased. Then, a phase shift film 30 having a film thickness of 183 nm was formed.

Next, the transparent substrate 20 with the phase shift film 30 after the surface treatment is carried into the second chamber, and argon (Ar) gas and nitrogen (N ₂ ) are introduced while the inside of the second chamber is evacuated to a predetermined degree of vacuum. A mixed gas (Ar: 65 sccm, N ₂ : 15 sccm) was introduced. Then, a sputtering power of 1.5 kW was applied to the second sputtering target made of chromium to form chromium nitride (CrN) containing chromium and nitrogen on the phase shift film 30 by reactive sputtering (film thickness 15 nm). Next, a mixed gas (30 sccm) of argon (Ar) gas and methane (CH ₄ : 4.9%) gas is introduced while the inside of the third chamber is kept at a predetermined degree of vacuum, and a third sputtering made of chromium is introduced. A sputtering power of 8.5 kW was applied to the target to form chromium carbide (CrC) containing chromium and carbon on CrN by reactive sputtering (thickness: 60 nm). Finally, while the fourth chamber was kept at a predetermined degree of vacuum, mixed gas of argon (Ar) gas and methane (CH ₄ : 5.5%) gas, nitrogen (N ₂ ) gas, and oxygen (O ₂ ) gas were mixed. A mixed gas (Ar + CH ₄ : 30 sccm, N ₂ : 8 sccm, O ₂ : 3 sccm) was introduced, and a sputtering power of 2.0 kW was applied to the fourth sputtering target made of chromium, and reactive sputtering was performed on CrC. A chromium carbooxynitride (CrCON) containing chromium, carbon, oxygen and nitrogen was formed on the substrate (thickness: 30 nm). As described above, the etching mask film 40 having the laminated structure of the CrN layer, the CrC layer and the CrCON layer was formed on the phase shift film 30 .
In this manner, a phase shift mask blank 10 having the phase shift film 30 and the etching mask film 40 formed on the transparent substrate 20 was obtained.

The transmittance and phase difference of the phase shift film 30 (the phase shift film 30 obtained by surface-treating the surface of the phase shift film 30 with an alkaline aqueous solution) of the obtained phase shift mask blank 10 were measured using MPM-100 manufactured by Lasertech. bottom. For the measurement of the transmittance and phase difference of the phase shift film 30, a substrate with a phase shift film (a substrate with a phase shift film 30 formed on the main surface of a synthetic quartz glass substrate ( dummy substrate) was used. The transmittance and phase difference of the phase shift film 30 were measured by taking out the substrate with the phase shift film (dummy substrate) from the chamber before forming the etching mask film 40 . As a result, the transmittance was 27% (wavelength: 405 nm) and the phase difference was 173° (wavelength: 405 nm). The film thickness of the phase shift film 30 surface-treated with an alkaline aqueous solution was 181 nm, which was reduced from the film thickness immediately after film formation.
Further, the change in flatness of the phase shift film 30 was measured using UltraFLAT 200M (manufactured by Corning TROPEL), and the film stress was calculated to be 0.5 GPa. This phase shift film 30 has a small amount of change in transmittance and a small amount of change in phase difference with respect to chemicals (sulfuric acid hydrogen peroxide, ammonia hydrogen peroxide, ozone water) used for cleaning the phase shift mask, and has high chemical resistance and cleaning resistance. had

Further, the rear surface reflectance of the phase shift film 30 was 4% at a wavelength of 365 nm, 6% at a wavelength of 405 nm, and 9% at a wavelength of 436 nm, which were very low values of 10% or less with respect to exposure light.
Further, the obtained phase shift mask blank was measured for film surface reflectance and optical density using a spectrophotometer SolidSpec-3700 manufactured by Shimadzu Corporation. The phase shift mask blank (etching mask film 40) had a film surface reflectance of 8.3% (wavelength: 436 nm) and an optical density OD of 4.0 (wavelength: 436 nm). It was found that this etching mask film functions as a light shielding film with low reflectance on the film surface.

Further, the obtained phase shift mask blank 10 was subjected to composition analysis in the depth direction by X-ray photoelectron spectroscopy (XPS). FIG. 5 shows the compositional analysis result of the phase shift mask blank of Example 1 in the depth direction by XPS. FIG. 5 shows the composition analysis results of the etching mask film 40 on the side of the phase shift film 30 and the phase shift film 30 in the phase shift mask blank. The horizontal axis of FIG. 5 indicates the depth (nm) in terms of SiO ₂ of the phase shift mask blank 10 with reference to the outermost surface of the etching mask film 40, and the vertical axis indicates the content (atomic %). In FIG. 5, each curve indicates changes in content of silicon (Si), nitrogen (N), oxygen (O), carbon (C), chromium (Cr), and molybdenum (Mo).

As shown in FIG. 5, in the composition analysis results in the depth direction by XPS for the phase shift mask blank 10, in the phase shift film 30, the proportion of oxygen varies stepwise and/or continuously in the depth direction. It monotonously increased, and the nitrogen ratio decreased stepwise and/or continuously in the depth direction. In addition, the magnitude of the slope of the oxygen increase in the 60% region of the central portion excluding the 20% region of the surface portion and the 20% region of the bottom portion with respect to the total thickness of the phase shift film 30 is It was 7 atomic %/100 nm in the depth direction and was 4 atomic %/100 nm or more. Also, the slope of nitrogen decrease was 7 atomic %/100 nm in the depth direction.
Further, as shown in FIG. 6, the content ratio of oxygen to silicon at the interface between the phase shift film 30 and the etching mask film 40 was 1.7, which satisfied the range of 0.5 to 2.0. This interface is the position where silicon is detected for the first time from the etching mask film 40 toward the phase shift film 30 when the phase shift mask blank 10 is subjected to composition analysis by X-ray photoelectron spectroscopy.

B. Phase shift mask and its manufacturing method In order to manufacture the phase shift mask 100 using the phase shift mask blank 10 manufactured as described above, first, on the etching mask film 40 of the phase shift mask blank 10, a resist coating apparatus is applied. was used to apply a photoresist film.
Thereafter, a photoresist film having a film thickness of 520 nm was formed through heating and cooling processes.
After that, a photoresist film was drawn using a laser drawing device, and a resist film pattern of a hole pattern with a hole diameter of 1.2 μm was formed on the etching mask film through development and rinsing steps.

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

After that, using the first etching mask film pattern 40a as a mask, the phase shift film 30 is wet-etched with a molybdenum silicide etchant obtained by diluting a mixed solution of ammonium hydrogen fluoride and hydrogen peroxide with pure water. A film pattern 30a was formed.
After that, the resist film pattern was peeled off.

After that, using a resist coating device, a photoresist film was coated so as to cover the first etching mask film pattern 40a.
Thereafter, a photoresist film having a film thickness of 520 nm was formed through heating and cooling processes.
After that, a photoresist film was drawn using a laser drawing device, and a second resist film pattern 60 for forming a light shielding band was formed on the first etching mask film pattern 40a through development and rinsing processes. .

Thereafter, using the second resist film pattern 60 as a mask, the first etching mask film pattern 40a formed in the transfer pattern forming region is wet-etched with a chromium etchant containing ceric ammonium nitrate and perchloric acid. bottom. This wet etching was performed with an over-etching time of 110% in order to make the cross-sectional shape vertical and to form a required fine pattern.
After that, the second resist film pattern 60 is removed.

In this way, on the transparent substrate 20, a phase shift film pattern 30a having a hole diameter of 1.5 μm and a light shielding band having a layered structure of the phase shift film pattern 30a and the etching mask film pattern 40b are formed in the transfer pattern formation region. A phase shift mask 100 was obtained.

A cross section of the obtained phase shift mask was observed with a scanning electron microscope. In the following Examples 1, 2 and Comparative Example 1, a scanning electron microscope was used to observe the cross section of the phase shift mask. 7 is a cross-sectional photograph of the phase shift mask of Example 1. FIG.

As shown in FIG. 7, the phase shift film pattern formed on the phase shift mask of Example 1 had a nearly vertical cross-sectional shape capable of sufficiently exhibiting the phase shift effect. In addition, in the phase shift film pattern, penetration was not observed either at the interface with the etching mask film pattern or at the interface with the substrate. Moreover, it had a phase shift film pattern with a small bottom width. Specifically, the cross section of the phase shift film pattern is composed of the top surface, the bottom surface and the side surfaces of the phase shift film pattern. In the cross section of this phase shift film pattern, the angle between the portion (upper side) where the upper surface and the side surface contact and the portion (lower side) where the side surface and the lower surface contact was 68 degrees. Therefore, a phase shift mask having an excellent phase shift effect in exposure light including light in the wavelength range of 300 nm or more and 500 nm or less, more specifically exposure light of compound light including i-line, h-line and g-line is provided. Got.

Therefore, when the phase shift mask of Example 1 is set on the mask stage of the exposure apparatus and is exposed and transferred to the resist film on the display device, it can be said that a fine pattern of less than 2.0 μm can be transferred with high accuracy. .

Example 2.
A. Phase Shift Mask Blank and Manufacturing Method Thereof To manufacture the phase shift mask blank of Example 2, as in Example 1, a synthetic quartz glass substrate of 1214 size (1220 mm×1400 mm) was prepared as a transparent substrate.
By the same method as in Example 1, the synthetic quartz glass substrate was carried into the chamber of the in-line type sputtering apparatus. The same sputtering target materials as in Example 1 were used as the first sputtering target, the second sputtering target, the third sputtering target, and the fourth sputtering target. Then, in a state where the inside of the first chamber is evacuated to a predetermined degree of vacuum, an inert gas composed of argon (Ar) gas, helium (He) gas, and nitrogen (N ₂ ) gas and monoxide, which is a reactive gas, are added. Nitrogen gas (NO) and mixed gas (Ar: 40 sccm, N ₂ : 34 sccm, He: 120 sccm, NO: 35.3 sccm) were introduced. That is, the flow rate ratio between the reactive gas and the inert gas is 0.18:1.0. Then, a first sputtering target containing molybdenum and silicon (molybdenum:silicon=1:12) is applied with a sputtering power of 7.0 kW to deposit molybdenum, silicon and oxygen on the main surface of the transparent substrate 20 by reactive sputtering. and nitrogen-containing molybdenum silicide oxynitride. Then, in the same manner as in Example 1, during this process, the above mixed gas is supplied from a gas supply pipe installed upstream of the sputtering target in the substrate transport direction, so that the main part of the transparent substrate 20 is In the oxynitride of molybdenum silicide deposited on the surface, the proportion of oxygen contained was progressively decreased, while the proportion of nitrogen was progressively increased. Then, a phase shift film 30 having a film thickness of 193 nm was formed. For the phase shift film 30 of Example 2, the gas flow rate was adjusted so that the oxygen content on the surface was 30% or less, so the surface treatment in Example 1 was not performed.
After forming the phase shift film on the transparent substrate, the substrate was taken out from the chamber and the surface of the phase shift film was washed with pure water. The pure water cleaning conditions were a temperature of 30 degrees and a cleaning time of 180 seconds.
Thereafter, an etching mask film 40 was formed by the same method as in Example 1. Next, as shown in FIG.
In this manner, a phase shift mask blank 10 having the phase shift film 30 and the etching mask film 40 formed on the transparent substrate 20 was obtained.

The transmittance and phase difference of the obtained phase shift film of the phase shift mask blank 10 (a phase shift film obtained by washing the surface of the phase shift film with pure water) were measured using MPM-100 manufactured by Lasertech. In order to measure the transmittance and phase difference of the phase shift film, a phase shift film-attached substrate (dummy) was prepared by setting the phase shift film 30 on the main surface of a synthetic quartz glass substrate set in the same tray. substrate) was used. The transmittance and phase difference of the phase shift film 30 were measured by taking out the substrate with the phase shift film (dummy substrate) from the chamber before forming the etching mask film. As a result, the transmittance was 47% (wavelength: 365 nm) and the phase difference was 183 degrees (wavelength: 365 nm). The film thickness of the phase shift film washed with pure water was 193 nm, which was unchanged from the film thickness immediately after film formation.

In addition, the rear surface reflectance of the phase shift film 30 was 4% at a wavelength of 365 nm, 6% at a wavelength of 405 nm, and 10% or less with respect to the exposure light, which were extremely low values.
Further, the obtained phase shift mask blank was measured for film surface reflectance and optical density using a spectrophotometer SolidSpec-3700 manufactured by Shimadzu Corporation. The phase shift mask blank (etching mask film) had a film surface reflectance of 8.3% (wavelength: 436 nm) and an optical density OD of 4.0 (wavelength: 436 nm). It was found that this etching mask film functions as a light shielding film with low reflectance on the film surface.

Further, composition analysis in the depth direction was performed on the obtained phase shift mask blank by X-ray photoelectron spectroscopy (XPS).

As a result, as in Example 1, in the phase shift film 30, the proportion of oxygen monotonously increases in the depth direction stepwise and/or continuously, and the proportion of nitrogen increases in the depth direction. There was a gradual and/or continuous decrease towards. Also, in the phase shift film 30, the gradient of oxygen decrease was 4 atomic %/100 nm in the depth direction, and the gradient of nitrogen increase was 4 atomic %/100 nm in the depth direction. .
Further, as shown in FIG. 6, the content ratio of oxygen to silicon at the interface between the phase shift film 30 and the etching mask film 40 was 0.9, satisfying the range of 0.5 to 2.0. This interface is the position where silicon is detected for the first time from the etching mask film 40 toward the phase shift film 30 when the composition of the phase shift mask blank 10 is analyzed by X-ray photoelectron spectroscopy from the etching mask film 40 side. and

B. Phase shift mask and its manufacturing method Using the phase shift mask blank manufactured as described above, a phase shift mask having a phase shift film pattern with a hole diameter of 1.5 μm was manufactured by the same method as in Example 1. . Wet etching of the phase shift film 30 was performed with an over-etching time of 110% in order to make the cross-sectional shape vertical and to form a required fine pattern.
A cross section of the obtained phase shift mask was observed with a scanning electron microscope. FIG. 8 is a cross-sectional photograph of the phase shift mask of Example 2. FIG.

As shown in FIG. 8, the phase shift film pattern formed on the phase shift mask of Example 2 had a nearly vertical cross-sectional shape capable of sufficiently exhibiting the phase shift effect. In addition, in the phase shift film pattern, penetration was not observed either at the interface with the etching mask film pattern or at the interface with the substrate. Moreover, it had a phase shift film pattern with a small bottom width. Specifically, the cross section of the phase shift film pattern is composed of the top surface, the bottom surface and the side surfaces of the phase shift film pattern. In the cross section of this phase shift film pattern, the angle between the portion (upper side) where the upper surface and the side surface contact and the portion (lower side) where the side surface and the lower surface contact was 66 degrees. Therefore, a phase shift mask having an excellent phase shift effect in exposure light including light in the wavelength range of 300 nm or more and 500 nm or less, more specifically exposure light of compound light including i-line, h-line and g-line is provided. Got.

Therefore, when the phase shift mask of Example 2 is set on the mask stage of the exposure apparatus and is exposed and transferred to the resist film on the display device, it can be said that a fine pattern of less than 2.0 μm can be transferred with high accuracy. .

Example 3.
A. Phase Shift Mask Blank and Manufacturing Method Thereof The phase shift mask blank of Example 3 is the phase shift mask blank of Example 1 that does not have the etching mask film.
In order to manufacture the phase shift mask blank of Example 3, as in Example 1, a synthetic quartz glass substrate of 1214 size (1220 mm×1400 mm) was prepared as the transparent substrate 20 .
A phase shift film 30 (thickness: 183 nm) made of oxynitride of molybdenum silicide was formed on a transparent substrate 20 by the same film formation method and film formation conditions as in Example 1. FIG.
After the phase shift film 30 was formed on the transparent substrate 20, it was taken out from the chamber and the surface of the phase shift film 30 was subjected to surface treatment under the same surface treatment conditions as in the first embodiment.
The phase shift film 30 of the obtained phase shift mask blank 10 was subjected to composition analysis in the depth direction by X-ray photoelectron spectroscopy (XPS). The proportion of nitrogen increased stepwise and/or continuously monotonically in the depth direction, and the nitrogen proportion decreased stepwise and/or continuously in the depth direction. In addition, the magnitude of the slope of the oxygen increase in the 60% region of the central portion excluding the 20% region of the surface portion and the 20% region of the bottom portion with respect to the total thickness of the phase shift film 30 is It was 7 atomic %/100 nm in the depth direction.

B. Phase shift mask and its manufacturing method In order to manufacture the phase shift mask 100 using the phase shift mask blank 10 manufactured as described above, first, the phase shift film 30 of the phase shift mask blank 10 is subjected to HMDS treatment ( After performing hexamethyldisilazane treatment), a photoresist film was coated and formed (thickness: 520 nm) in the same manner as in Example 1 using a resist coating apparatus.
Next, in the same manner as in Example 1, a photoresist film is drawn using a laser lithography device, developed and rinsed, and a resist film pattern of a hole pattern with a hole diameter of 1.2 μm is formed on the phase shift film 30 . formed.
Thereafter, using the resist film pattern as a mask, the phase shift film 30 is wet-etched with a molybdenum silicide etchant obtained by diluting a mixed solution of ammonium hydrogen fluoride and hydrogen peroxide with pure water to form a phase shift film pattern 30a. bottom.
After that, the resist film pattern was peeled off.
Thus, a phase shift mask 100 having a phase shift film pattern 30a with a hole diameter of 1.5 μm formed in the transfer pattern formation region on the transparent substrate 20 was obtained.

When the cross-sectional shape of the phase shift film pattern was observed in the same manner as in Example 1, it was found that, in the cross section of the phase shift film pattern, a portion (upper edge) where the upper surface and the side surface were in contact and a portion (lower edge) where the side surface and the lower surface were in contact. The angle was 62 degrees. Therefore, a phase shift mask having an excellent phase shift effect in exposure light including light in the wavelength range of 300 nm or more and 500 nm or less, more specifically exposure light of compound light including i-line, h-line and g-line is provided. Got.
Therefore, when the phase shift mask of Example 3 is set on the mask stage of the exposure apparatus and is exposed and transferred to the resist film on the display device, it can be said that a fine pattern of less than 2.0 μm can be transferred with high accuracy. .

Although molybdenum is used as the transition metal in the above-described embodiments, the same effects as those described above can be obtained with other transition metals.
Moreover, in the above-described embodiments, examples of phase shift mask blanks for manufacturing display devices and phase shift masks for manufacturing display devices have been described, but the present invention is not limited to these. The phase shift mask blank and phase shift mask of the present invention can also be applied to semiconductor device manufacturing, MEMS manufacturing, printed circuit boards, and the like.
Also, in the above embodiment, the size of the transparent substrate is 1214 size (1220 mm×1400 mm×13 mm), but it is not limited to this. In the case of a phase shift mask blank for manufacturing a display device, a large size transparent substrate is used, and the size of the transparent substrate has a side length of 300 mm or more. The size of the transparent substrate used for phase shift mask blanks for manufacturing display devices is, for example, 330 mm×450 mm or more and 2280 mm×3130 mm or less.
In the case of phase shift mask blanks for manufacturing semiconductor devices, MEMS, and printed circuit boards, a small size transparent substrate is used, and the size of the transparent substrate is 9 inches or less on one side. be. The size of the transparent substrate used for the phase shift mask blank for the above application is, for example, 63.1 mm×63.1 mm or more and 228.6 mm×228.6 mm or less. Normally, 6025 size (152 mm x 152 mm) and 5009 size (126.6 mm x 126.6 mm) are used for semiconductor manufacturing and MEMS manufacturing, and 7012 size (177.4 mm x 177.4 mm) is used for printed circuit boards. Alternatively, the 9012 size (228.6 mm×228.6 mm) is used.

Comparative example 1.
A. Phase Shift Mask Blank and Manufacturing Method Thereof To manufacture the phase shift mask blank of Comparative Example 1, a synthetic quartz glass substrate of 1214 size (1220 mm×1400 mm) was prepared as a transparent substrate in the same manner as in Example 1.
By the same method as in Example 1, the synthetic quartz glass substrate was carried into the chamber of the in-line type sputtering apparatus. Then, an inert gas composed of argon (Ar) gas and nitrogen (N ₂ ) gas and nitrogen monoxide gas (NO), which is a reactive gas, are added in a state where the inside of the first chamber is kept at a predetermined degree of vacuum. , (Ar: 40 sccm, N ₂ : 34 sccm, NO: 34.5 sccm) was introduced. That is, the flow rate ratio between the reactive gas and the inert gas is 0.47:1. Then, a sputtering power of 7.0 kW was applied to a first sputtering target (molybdenum:silicon=1:4) containing molybdenum and silicon to form molybdenum, silicon, and oxygen on the main surface of the transparent substrate by reactive sputtering. A process was performed to deposit an oxynitride of molybdenum silicide containing nitrogen. In this process, the mixed gas is supplied from a gas supply pipe installed downstream of the sputtering target with respect to the transport direction of the substrate, thereby depositing molybdenum silicide oxynitride on the main surface of the transparent substrate. , the proportion of oxygen contained is gradually increased, while the proportion of nitrogen is gradually decreased. Thus, a phase shift film having a thickness of 199 nm was formed.
Also, after forming the phase shift film on the transparent substrate, the transparent substrate was taken out from the chamber, and the surface of the phase shift film was treated with an alkaline aqueous solution. The surface treatment conditions were an alkali concentration of 0.7%, a temperature of 30° C., and a surface treatment time of 1200 seconds.
After that, an etching mask film was formed by the same method as in Examples 1 and 2.
Thus, a phase shift mask blank was obtained in which the phase shift film and the etching mask film were formed on the transparent substrate.

The transmittance and phase difference of the obtained phase shift mask blank (the phase shift film obtained by surface-treating the surface of the phase shift film with an alkaline aqueous solution) were measured using MPM-100 manufactured by Lasertech. For the measurement of the transmittance and phase difference of the phase shift film, a substrate with a phase shift film (dummy substrate) was prepared by setting the phase shift film on the main surface of a synthetic quartz glass substrate set in the same tray. ) was used. The transmittance and phase difference of the phase shift film were measured by taking out the substrate with the phase shift film (dummy substrate) from the chamber before forming the etching mask film. As a result, the transmittance was 29% (wavelength: 405 nm) and the phase difference was 166 degrees (wavelength: 405 nm). The film thickness of the phase shift film washed with pure water was 197 nm, which was a decrease from the film thickness immediately after film formation.
In addition, this phase shift film has a small amount of change in transmittance and a small amount of change in phase difference against chemicals (sulfuric acid hydrogen peroxide, ammonia hydrogen peroxide, ozone water) used for cleaning phase shift masks, and has high chemical resistance and cleaning resistance. had sex.

Further, the obtained phase shift mask blank was measured for film surface reflectance and optical density using a spectrophotometer SolidSpec-3700 manufactured by Shimadzu Corporation. The phase shift mask blank (etching mask film) had a film surface reflectance of 8.3% (wavelength: 436 nm) and an optical density OD of 4.0 (wavelength: 436 nm). It was found that this etching mask film functions as a light shielding film with low reflectance on the film surface.
The rear surface reflectance of the obtained phase shift mask blank was 7% at a wavelength of 365 nm, 11% at a wavelength of 405 nm, and 12% at a wavelength of 436 nm. ), the value exceeded 10%.

Further, composition analysis in the depth direction was performed on the obtained phase shift mask blank by X-ray photoelectron spectroscopy (XPS). FIG. 9 shows the compositional analysis result of the phase shift mask blank of Comparative Example 1 in the depth direction by XPS. FIG. 9 shows the etching mask film on the phase shift film side of the phase shift mask blank and the composition analysis results of the phase shift film. The horizontal axis of FIG. 9 indicates the depth (nm) of the phase shift mask blank converted to SiO ₂ with reference to the outermost surface of the etching mask film, and the vertical axis indicates the content (atomic %). In FIG. 9, each curve indicates changes in content of silicon (Si), nitrogen (N), oxygen (O), carbon (C), chromium (Cr), and molybdenum (Mo).

As shown in FIG. 9, in the depth direction composition analysis result by XPS for the phase shift mask blank, in the phase shift film, the oxygen ratio monotonously decreases in the depth direction, and the nitrogen ratio is It monotonically increases in the depth direction. Further, as shown in FIG. 6, the content ratio of oxygen to silicon at the interface between the phase shift film and the etching mask film was 1.1.

B. Phase shift mask and manufacturing method thereof A phase shift mask was manufactured by the same method as in Examples 1 and 2 using the phase shift mask blank manufactured as described above. Wet etching of the phase shift film was performed with an over-etching time of 120% in order to make the cross-sectional shape vertical and to form a required fine pattern.
A cross section of the obtained phase shift mask was observed with a scanning electron microscope. 10 is a cross-sectional photograph of the phase shift mask of Comparative Example 1. FIG.

As shown in FIG. 10, the phase shift film pattern formed on the phase shift mask of Comparative Example 1 had a linear tapered shape. In the cross section of this phase shift film pattern, the angle between the portion (upper side) where the upper surface and the side surface contact and the portion (lower side) where the side surface and the lower surface contact was 30 degrees. Therefore, in the obtained phase shift mask, exposure light including light in the wavelength range of 300 nm or more and 500 nm or less, more specifically exposure light of compound light including i-line, h-line and g-line, has sufficient phase. No shift effect.
For this reason, when the phase shift mask of Comparative Example 1 is set on the mask stage of an exposure apparatus and is exposed and transferred to a resist film on a display device, it is expected that a fine pattern of less than 2.0 μm cannot be transferred. .

DESCRIPTION OF SYMBOLS 10... Phase shift mask blank, 20... Transparent substrate, 30... Phase shift film,
30a... phase shift film pattern, 40... etching mask film,
40a... First etching mask film pattern,
40b... second etching mask film pattern, 50... first resist film pattern,
60... Second resist film pattern, 100... Phase shift mask

Claims (10)

A phase shift mask blank having a phase shift film on a transparent substrate,
The phase shift film contains a transition metal, silicon, oxygen, and nitrogen, and the total content of light element components containing oxygen and nitrogen is 50 atomic % or more,
In the phase shift film, the proportion of oxygen increases stepwise and/or continuously in the depth direction, and the proportion of nitrogen decreases stepwise and/or continuously in the depth direction. and
A phase shift mask blank, wherein the rear surface reflectance of the phase shift film is 15% or less in a wavelength range of 365 nm or more and 436 nm or less . 2. The phase according to claim 1, wherein the phase shift film has a phase difference of 160° or more and 200° or less with respect to exposure light and a transmittance of 15% or more and 80% or less. Shift mask blank. 3. A phase shift mask blank according to claim 1, wherein said phase shift film is composed of a plurality of layers. 3. A phase shift mask blank according to claim 1, wherein said phase shift film is composed of a single layer. 5. The phase according to any one of claims 1 to 4, further comprising an etching mask film made of a material having etching resistance to an etchant used to etch the phase shift film, on the phase shift film. Shift mask blank. 6. The phase shift mask blank according to claim 5, wherein said phase shift film has a content ratio of oxygen to silicon at an interface with said etching mask film of 0.5 or more and 2.0 or less. 7. A phase shift mask blank according to claim 5, wherein said etching mask film is made of a chromium-based material. providing a phase shift mask blank according to any one of claims 1 to 4;
forming a resist film on the phase shift mask blank;
A resist film pattern is formed by drawing and developing a desired pattern on the resist film, and the phase shift film is formed on the transparent substrate by wet etching using the resist film pattern as a mask. and forming a pattern. providing a phase shift mask blank according to any one of claims 5 to 7;
forming a resist film on the phase shift mask blank;
A resist film pattern is formed by drawing and developing a desired pattern on the resist film, and using the resist film pattern as a mask, the etching mask film is patterned by wet etching to form an etching mask film pattern. process and
and forming a phase shift film pattern on the transparent substrate by wet etching the phase shift film using the etching mask film pattern as a mask. A phase shift mask manufactured using the phase shift mask blank according to any one of claims 1 to 7, or a phase shift mask manufactured by the method for manufacturing a phase shift mask according to claim 8 or 9. A method of manufacturing a display device, comprising a step of exposing and transferring a transfer pattern onto a resist film on the display device using a mask.

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