JP2021004920A - Mask blank, method for manufacturing transfer mask and method for manufacturing semiconductor device - Google Patents

Abstract

To provide a mask blank capable of resolving a pattern with a line width narrower than a wavelength of a laser beam of a laser drawing device onto a resist film.SOLUTION: A mask blank has a structure including a thin film 2 for transfer pattern formation and a resist film 3, laminated on a substrate 1 in this order. The thin film 2 is composed of a material containing a metal element. If an in-plane distribution of a reflective index to exposure light within a transfer pattern formation area on a surface of the resist film 3 is ΔR[%] and an in-plane distribution of a film thickness within the transfer pattern formation area of the resist film 3 is Δd[nm], ΔR/Δd[%/nm] is 0.1 or less, Δd[nm] is larger than zero, and a wavelength of the exposure light is a wavelength selected from a wavelength region of 350-420 nm.SELECTED DRAWING: Figure 1

Description

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

Generally, in the manufacturing process of a semiconductor device, a fine pattern is formed by using a photolithography method. In addition, a number of transfer masks are usually used to form this fine pattern. This transfer mask generally has a light-shielding fine pattern made of a metal thin film or the like provided on a translucent glass substrate, and a photolithography method is also used in the manufacture of this transfer mask.

A mask blank having a light-shielding film on a translucent substrate such as a glass substrate is used for manufacturing a transfer mask by a photolithography method. In the production of a transfer mask using this mask blank, an exposure step of applying a desired pattern exposure to a resist film formed on the mask blank and a resist film being developed according to a desired pattern exposure to obtain a resist pattern. A developing step of forming, an etching step of etching the light-shielding film along the resist pattern, and a step of peeling and removing the remaining resist pattern are performed. In the above developing step, a resist film formed on a mask blank is exposed to a desired pattern, and then a developing solution is supplied to dissolve a portion of the resist film soluble in the developing solution to form a resist pattern. .. Further, in the etching step, using this resist pattern as a mask, a portion where the light-shielding film on which the resist pattern is not formed is exposed is melted by dry etching, whereby a desired mask pattern is formed on the translucent substrate. .. In this way, the transfer mask is completed.

For example, Patent Document 1 discloses a mask blank provided with a light-shielding film made of a chrome-based material. Further, in Patent Document 2, a step of forming an i-line resist film on a light-shielding film made of a chromium-based material, a step of exposing a pattern with a laser exposure apparatus, a step of forming a resist pattern by performing a developing process, and the like, a resist. A step of forming a pattern on a light-shielding film by performing etching using the pattern as a mask is disclosed.

Patent No. 3276954 Japanese Unexamined Patent Publication No. 2004-07780

In order to expose (expose) a fine pattern on the resist film, exposure drawing with an electron beam is suitable. However, the conventional electron beam writing apparatus has a problem that it takes a lot of time to expose and draw a pattern on a resist film. The main reason is that the electron beam irradiator (electron gun) is based on the principle of exposing and drawing a pattern with a so-called one-stroke writing, and that a normal electron beam drawing device is equipped with only one electron beam irradiator. is there.

On the other hand, the laser drawing apparatus includes a mechanism capable of irradiating a plurality of laser beams from one laser light source onto the resist film. Therefore, there is an advantage that the speed of exposure drawing by laser light is significantly faster than that of exposure drawing by electron beam. In addition, although the line width of exposure drawing with an electron beam is significantly smaller than the line width of a laser beam, it is not always required to create a transfer pattern with the line width of an electron beam, and exposure with an electron beam is not always required. Drawing may not be required. If the number of cases in which it is not necessary to use an electron beam exposure drawing apparatus for exposure drawing of a mask blank on a resist film increases, resources can be effectively used. In addition, the throughput of exposure drawing of the pattern on the resist film of the mask blank is also significantly improved.

However, the wavelength of the laser light used in the laser drawing apparatus is about 350 nm at the shortest. On the other hand, the line width of the transfer pattern may be smaller than that of about 300 nm. Conventionally, in exposure drawing by a laser drawing device, even if a pattern having a line width narrower than the wavelength of the laser beam used for exposure drawing is exposed on a mask blank resist film, when the resist film after exposure drawing is developed. It was difficult to resolve the pattern drawn by exposure on the resist film.

The present invention has been made to solve the above-mentioned conventional problems, and is a mask blank and a transfer mask capable of resolving a pattern having a line width narrower than the wavelength of the laser beam of a laser drawing apparatus on a resist film. It is an object of the present invention to provide a manufacturing method of a semiconductor device and a manufacturing method of a semiconductor device.

In order to achieve the above object, the present invention has the following configuration.
(Structure 1)
A mask blank having a structure in which a thin film for forming a transfer pattern and a resist film are laminated in this order on a substrate.
The thin film is made of a material containing a metal element.
The in-plane distribution of the reflectance with respect to the exposure light in the transfer pattern forming region on the surface of the resist film is ΔR [%], and the in-plane distribution of the film thickness in the transfer pattern forming region of the resist film is Δd [nm]. When, ΔR / Δd [% / nm] is 0.1 or less, and Δd [nm] is larger than zero.
A mask blank characterized in that the wavelength of the exposure light is a wavelength selected from a wavelength region of 350 nm or more and 420 nm or less.

(Structure 2)
The mask blank according to the configuration 1, wherein the in-plane distribution ΔR of the reflectance is 0.4% or less.

(Structure 3)
The mask blank according to the configuration 1 or 2, wherein the reflectance of the resist film with respect to the exposure light is 5% or less.

(Structure 4)
The mask blank according to any one of configurations 1 to 3, wherein the transfer pattern forming region is an inner region of a square having a side of 132 mm with respect to the center of the substrate.

(Structure 5)
The mask blank according to any one of configurations 1 to 4, wherein the in-plane distribution of the film thickness of the resist film in the transfer pattern forming region is 5 nm or less.

(Structure 6)
The mask blank according to any one of configurations 1 to 5, wherein the wavelength of the exposure light is a wavelength selected from a wavelength region of 400 nm or more and 420 nm or less.

(Structure 7)
The thickness of the resist film is characterized in that it is in the range of 260 nm or more and 290 nm or less, 320 nm or more and 350 nm or less, 385 nm or more and 415 nm or less, or 445 nm or more and 475 nm or less. The mask blank according to the configuration 6.

(Structure 8)
The mask blank according to any one of configurations 1 to 7, wherein the resist film is made of a material that is exposed to exposure light in the wavelength region.

(Structure 9)
The mask blank according to any one of configurations 1 to 8, wherein the thin film is made of a material containing chromium.

(Structure 10)
The mask blank according to the configuration 9, wherein the thin film is a composition gradient film in which the chromium content changes in the thickness direction.

(Structure 11)
The mask blank according to any one of configurations 1 to 10, wherein the thin film is a light-shielding film having an optical density of 3 or more with respect to the exposure light.

(Structure 12)
A method for manufacturing a transfer mask using the mask blank according to any one of configurations 1 to 11.
A step of exposing the resist film with the transfer pattern with the exposure light and then performing a developing process to form a resist film having the transfer pattern.
A method for producing a transfer mask, which comprises a step of forming a transfer pattern on the thin film by etching using a resist film having the transfer pattern as a mask.

(Structure 13)
The method for producing a transfer mask according to Configuration 12, wherein the step of forming the transfer pattern on the thin film is to form the transfer pattern on the thin film by dry etching using a gas containing chlorine.

(Structure 14)
A method for manufacturing a semiconductor device, which comprises a step of exposing and transferring a transfer pattern to a resist film on a semiconductor substrate using the transfer mask manufactured by the method for manufacturing a transfer mask according to the configuration 12 or 13.

According to the mask blank according to the present invention, a pattern having a line width narrower than the wavelength of the laser light of the laser drawing apparatus can be resolved on the resist film. As a result, it is possible to increase the number of cases in which it is not necessary to use an electron beam exposure drawing apparatus for exposure drawing of the mask blank on the resist film, and it is possible to effectively utilize resources.

It is a schematic diagram which shows the structure of the mask blank in embodiment of this invention. It is a schematic diagram which shows the manufacturing process of the transfer mask in embodiment of this invention. It is a graph which shows the relationship between the reflectance at an exposure wavelength of 413 nm and the resist film thickness of the mask blank corresponding to Example 1 and Comparative Example 1. It is a graph which shows the relationship between the reflectance at an exposure wavelength of 404 nm and the resist film thickness of the mask blank corresponding to Example 1 and Comparative Example 1.

First, the background to the present invention will be described.
The present inventors have diligently studied the configuration of a mask blank for resolving a pattern having a line width narrower than the wavelength of the laser beam of a laser drawing apparatus on a resist film. A mask blank for manufacturing a transfer mask includes a thin film for forming a transfer pattern on a substrate, and a resist film is formed on the thin film. Further, as the exposure wavelength of the laser light (that is, the exposure light) used in the laser drawing apparatus, one having a wavelength region of 350 nm or more and 420 nm or less is usually used. The present inventor created a plurality of mask blanks by changing the film forming conditions of the thin film for forming the transfer pattern without changing the film forming conditions of the resist film. As the exposure light used for laser drawing, a plurality of laser lights having different wavelengths were selected from the above wavelength range. Then, laser drawing was performed on the resist film of each of the above mask blanks using each of the above selected laser beams. Further, the resist film of each mask blank after drawing was subjected to development processing, and the resolution accuracy of the pattern (resist pattern) formed on the resist film of each mask blank was compared. As a result, it was found that even if the resist film has the same material and film thickness, there is a large difference in the resolution accuracy of the resist pattern due to the characteristics of the thin film for forming the transfer pattern.

The present inventor further investigated the factors that affect the resolution accuracy of the resist pattern, and found that the in-plane distribution (thickness) of the film thickness in the transfer pattern formation region of the resist film was due to the characteristics of the thin film for forming the transfer pattern. It was found that the in-plane distribution of reflectance (variation of reflectance) has a great influence on (variation of reflectance). The resist film is usually formed by spin coating on a rectangular thin film. Therefore, it is very difficult to make the in-plane distribution of the film thickness zero, and an in-plane distribution of a certain degree of film thickness occurs. However, even if the resist film has an in-plane distribution of the same film thickness, the in-plane distribution of the reflectance of the resist film becomes very large depending on the characteristics of the thin film for forming a transfer pattern, and the resolution is improved. It turned out to be worse. Then, the present inventor divides the in-plane distribution of the reflectance in the transfer pattern forming region of the resist film formed on the thin film by the in-plane distribution of the film thickness in the transfer pattern forming region of the resist film. It was found that the resolution of the resist film can be improved by forming the thin film so that it is within a certain range.

That is, the mask blank of the present invention is a mask blank having a structure in which a thin film for forming a transfer pattern and a resist film are laminated in this order on a substrate, and the thin film is made of a material containing a metal element and is a resist film. When the in-plane distribution of the reflectance with respect to the exposure light in the transfer pattern forming region of the surface is ΔR [%] and the in-plane distribution of the film thickness in the transfer pattern forming region of the resist film is Δd [nm], ΔR It is characterized in that / Δd [% / nm] is 0.1 or less, Δd [nm] is larger than zero, and the wavelength of the exposure light is a wavelength selected from a wavelength region of 350 nm or more and 420 nm or less. Is. The wavelength of the exposure light is more preferably a wavelength selected from a wavelength region of 400 nm or more and 420 nm or less. In the description of this embodiment, unless otherwise specified, the exposure light refers to the laser light used in the laser drawing apparatus.

FIG. 1 details embodiments of the present invention with reference to the following drawings.
FIG. 1 is a schematic view showing the configuration of a mask blank according to the embodiment of the present invention. The mask blank 10 of FIG. 1 has a structure in which a light-shielding film 2 and a resist film 3 are laminated in this order on a translucent substrate 1. Here, as the translucent substrate 1, a glass substrate is generally used. Since the glass substrate is excellent in flatness and smoothness, when pattern transfer is performed on a semiconductor substrate using a transfer mask, high-precision pattern transfer can be performed without distortion of the transfer pattern. As the material of the glass substrate, synthetic quartz glass, aluminosilicate glass, soda-lime glass, low thermal expansion glass (SiO _2- TiO ₂ glass, etc.) can be used.

The mask blank 10 in the present embodiment includes a light-shielding film 2 as a thin film for forming a transfer pattern. The light-shielding film 2 is made of a material containing a metal element. As the metal element, it is preferable that the metal element is formed of a material containing chromium. As the material containing chromium, it may be a simple substance of chromium, or it may be a material containing chromium and an additive element. As such an additive element, oxygen and / or nitrogen are preferable in that the dry etching rate can be increased. The light-shielding film 2 may also contain elements such as carbon, hydrogen, boron, indium, tin, and molybdenum. The light-shielding film 2 may be made of a material other than the chromium-based material as long as it satisfies the optical characteristics described below. For example, a silicon-based material, a transition metal silicide-based material, a tantalum-based material, or the like may be applied to the material that forms the light-shielding film 2 within the range that satisfies the required optical characteristics.

The light-shielding film 2 has a film surface reflectance of 15% with respect to a laser drawing wavelength (laser light having a wavelength within the above wavelength region) when the resist film is not laminated (that is, the upper surface of the light-shielding film 2 is exposed). Hereinafter, it is preferable that the film is controlled so as to be 13% or less. Further, the light-shielding film 2 is a film controlled so that the transmittance with respect to the laser drawing wavelength (laser light having a wavelength within the above wavelength region) is 0.1% or less, further 0.05% or less. preferable.

The method for forming the light-shielding film 2 is not particularly limited, but a film forming method using an in-line sputtering apparatus is preferable. By forming a film with an in-line sputtering apparatus, an oxide layer is not formed in the film, so that it becomes easy to strictly control the optical characteristics (reflectance, etc.). Further, the light-shielding film 2 is preferably a composition gradient film in which the chromium content changes in the thickness direction, because it can be formed by an in-line sputtering apparatus. However, the configuration of the light-shielding film 2 is not limited to this, and may be a single-layer film or a laminated film.

The film thickness of the light-shielding film 2 is preferably 150 nm or less, and more preferably 120 nm or less. By reducing the film thickness to some extent, the aspect ratio of the pattern (ratio of the pattern depth to the pattern width) can be reduced, and line width errors due to the global loading phenomenon and the microloading phenomenon can be reduced. The light-shielding film 2 in the present invention can obtain a desired optical density (usually 3.0 or more) even if the film thickness is 150 nm or less at an exposure wavelength of 350 nm or more and 420 nm or less. The lower limit of the film thickness of the light-shielding film 2 can be reduced as long as a desired optical density can be obtained.

In order to obtain a high resolution, the material of the resist film 3 is preferably formed of a material that is exposed to the exposure light in the wavelength region. The resist material is not particularly limited, but may be a positive resist material, a negative resist material, a non-chemically amplified resist, or a chemically amplified resist. The resist film 3 preferably has a refractive index n of 1.90 or less with respect to light in a wavelength region of 350 nm or more and 420 nm or less, and more preferably 1.80 or less. Further, the resist film 3 preferably has a refractive index n with respect to light in the wavelength region of 1.50 or more, and more preferably 1.60 or more. On the other hand, the resist film 3 preferably has an extinction coefficient k of 0.01 or more, and more preferably 0.02 or more, with respect to light in the wavelength region. Further, the resist film 3 preferably has an extinction coefficient k with respect to light in the wavelength region of 0.06 or less, and more preferably 0.05 or less.

The main surface of the mask blank 10 on the side where the light-shielding film 2 is provided has a transfer pattern-forming region in which a transfer pattern is formed and a non-transfer pattern-forming region located outside the transfer pattern-forming region. When the mask blank substrate is, for example, a 6-inch square (square of about 152 mm × about 152 mm) glass substrate, the transfer pattern forming region is an inner region of a square having a side of 132 mm with respect to the center of the substrate 1. Is preferable. Further, a region having a range of 132 mm × 104 mm or a region having a range of 104 mm × 132 mm may be used as a transfer pattern forming region. Of course, these are examples, and can be appropriately set according to the configuration of the transfer mask produced by using this mask blank.

In the mask blank 10, the in-plane distribution of the reflectance with respect to the exposure light in the transfer pattern forming region on the surface of the resist film 3 is ΔR [%], and the in-plane distribution of the film thickness in the transfer pattern forming region of the resist film 3 is set. When Δd [nm], ΔR / Δd [% / nm] is 0.1 or less, and more preferably 0.09 or less. The in-plane distribution Δd of the film thickness is measured by setting measurement points in a grid pattern at predetermined intervals in the transfer pattern forming region and measuring the film thickness of the resist film 3 at each measurement point. Δd can be measured by subtracting the minimum value from the maximum value of. Further, in the measurement of the in-plane distribution ΔR of the reflectance, the reflectance of the resist film 3 is measured at each measurement point by setting the measurement points in a grid pattern at 6 mm intervals in the transfer pattern forming region, and the measured reflectance is measured. ΔR can be measured by subtracting the minimum value from the maximum value of the rate. Here, the predetermined interval is preferably 4 mm or less, and more preferably 1 mm or less. It should be noted that the above measurement method is merely an example, and it goes without saying that the measurement method is not limited to this.
After satisfying the above conditions of ΔR / Δd, the in-plane distribution ΔR of the reflectance is preferably 0.4% or less, and more preferably 0.38 or less. The in-plane distribution Δd of the film thickness is preferably 5 nm or less, and more preferably 4 nm or less.

The reflectance of the resist film 3 with respect to the exposure light is preferably 5% or less, and more preferably 4% or less. This is because the photosensitivity of the resist film can be increased by reducing the reflectance.
In addition, a periodic correlation was found between the thickness of the resist film 3 formed on the light-shielding film 2 and the reflectance of the laser beam. In exposure light having a wavelength of 400 nm or more and 420 nm or less, the resist film 3 has a thickness of 275 nm, 335 nm, 400 nm, 460 nm, or a vicinity thereof (± 15 nm), and has a periodic peak (peak) or valley of reflectance. (Valley) was seen. Therefore, in order to reduce the in-plane distribution ΔR [%] of the reflectance, the thickness of the resist film 3 is in the range of 260 nm or more and 290 nm or less, in the range of 320 nm or more and 350 nm or less, in the range of 385 nm or more and 415 nm or less, or 445 nm. It is preferably in the range of 475 nm or less.

In the mask blank 10, a phase shift film may be provided between the translucent substrate 1 and the light shielding film 2. The transfer mask (phase shift mask) manufactured from the mask blank in this case has a transfer pattern on the phase shift film, but the light shielding film 2 is limited to a relatively sparse pattern such as a light shielding band. However, even with the mask blank in this case, when the transfer pattern to be formed on the phase shift film is exposed and drawn on the resist film with laser light, the light-shielding film 2 exists directly under the resist film. Therefore, in order for the resist film to resolve a transfer pattern having a line width narrower than the wavelength of the laser light, the light-shielding film 2 is required to have the above optical characteristics.

Next, a method of manufacturing the transfer mask 20 using the mask blank 10 shown in FIG. 1 will be described. In the method of manufacturing the transfer mask 20 using the mask blank 10, the resist film 3 is exposed to the transfer pattern with exposure light and then developed to obtain a resist film (resist pattern 3a) having the transfer pattern. It includes a step of forming and a step of forming a transfer pattern on the light-shielding film 2 by etching using the resist pattern 3a as a mask.

FIG. 2 is a schematic view showing in order the manufacturing process of the transfer mask 20 using the mask blank 10.
FIG. 2A shows a state in which the resist film 3 is formed on the light-shielding film 2 of the mask blank 10 of FIG.
Next, FIG. 2B shows an exposure step of applying a desired pattern exposure to the resist film 3 formed on the mask blank 10. The pattern exposure is performed using a laser drawing apparatus or the like. As the above-mentioned resist material, a material having photosensitivity corresponding to laser exposure light is used.
Next, FIG. 2C shows a developing step of developing the resist film 3 according to a desired pattern exposure to form a resist pattern 3a. In the developing step, the resist film 3 formed on the mask blank 10 is exposed to a desired pattern, and then a developing solution is supplied to dissolve the portion of the resist film soluble in the developing solution to form the resist pattern 3a. Form.

Next, FIG. 2D shows an etching step of etching the light-shielding film 2 along the resist pattern 3a. In the present invention, it is preferable to use dry etching. In the etching step, using the resist pattern 3a as a mask, the portion where the light-shielding film 2 on which the resist pattern 3a is not formed is exposed is melted by dry etching, whereby the desired light-shielding pattern 2a is formed on the translucent substrate 1. Form to.
The step of forming the light-shielding pattern 2a on the light-shielding film 2 is preferably performed by dry etching using a gas containing chlorine. By performing dry etching using the above dry etching gas, the dry etching rate can be increased, the dry etching time can be shortened, and a light-shielding pattern 2a having a good cross-sectional shape can be formed. .. Examples of the chlorine-based gas used for the dry etching gas include Cl ₂ , SiCl ₄ , HCl, CCl ₄ , CHCl _{3, and the} like. Further, for dry etching, a dry etching gas composed of a mixed gas containing oxygen gas or the like may be used in addition to the chlorine-based gas.

FIG. 2E shows a transfer mask 20 obtained by peeling and removing the remaining resist pattern 3a. In this way, a transfer mask in which the light-shielding pattern 2a having a good cross-sectional shape is formed with high accuracy is completed.
The present invention is not limited to the embodiments described above. That is, it is not limited to the so-called binary mask mask blank in which a light-shielding film is formed on a translucent substrate, and for example, a mask blank for use in manufacturing a halftone type phase shift mask or a Levenson type phase shift mask. Good. In this case, the structure is such that a light-shielding film is formed on the halftone phase-shift film on the translucent substrate, and the desired optical density (preferably 3.0 or more) can be obtained by combining the halftone phase-shift film and the light-shielding film. As long as it is obtained, the optical density of the light-shielding film itself can be set to a value smaller than, for example, 3.0.

The method for manufacturing a semiconductor device of the present invention is characterized by comprising a step of exposing and transferring a transfer pattern to a resist film on a semiconductor substrate using the transfer mask 20 manufactured by the method for manufacturing the transfer mask 20 described above. .. Therefore, the transfer mask 20 is set in an exposure apparatus, and a KrF excimer laser or i-ray is irradiated from the translucent substrate 1 side of the transfer mask 20 to transfer an object (resist film on a semiconductor wafer, etc.). Even if the exposure transfer is performed on a wafer, a desired pattern can be transferred to the transfer target with high accuracy.

Hereinafter, embodiments of the present invention will be described in more detail with reference to Examples.
(Example 1)
[Manufacturing of mask blank]
A translucent substrate 1 made of synthetic quartz glass having a main surface size of about 152 mm × about 152 mm and a thickness of about 6.35 mm was prepared. The translucent substrate 1 had an end face and a main surface polished to a predetermined surface roughness, and then subjected to a predetermined cleaning treatment and a drying treatment.

A light-shielding film 2 having a composition-inclined structure was formed on the translucent substrate 1 by using an in-line sputtering apparatus. A Cr target is arranged in each space (sputtering chamber) continuously arranged in the in-line sputtering apparatus in the substrate conveying direction, and reactive sputtering is performed while conveying the translucent substrate 1 in each space. The light-shielding film 2 was formed in. Specifically, first, the lower region of the light-shielding film 2 containing CrN as a main component was formed with a thickness of 16 nm using Ar gas and N ₂ gas as sputtering gases. Next, Ar gas and CH ₄ gas were used as sputtering gases, and a central region containing CrC as a main component was formed with a thickness of 63 nm. Further, an upper region containing CrON as a main component was formed with a thickness of 24 nm using Ar gas and NO gas as sputtering gases. By the above steps, a light-shielding film 2 was formed on the translucent substrate 1 with a thickness of 103 nm.

The central region of the light-shielding film 2 contains N (nitrogen) due to the N ₂ gas and NO gas used for film formation in the lower region and the upper region, and all of the lower region, the central region, and the upper region include N (nitrogen). Cr and N were included. The chromium content of the three regions of the light-shielding film 2 increased in the order of the upper region, the lower region, and the middle region. The average content of the lower region of the light-shielding film 2 was about 60 atomic% for chromium, about 34 atomic% for nitrogen, and about 6 atomic% for carbon. The average content of the central region of the light-shielding film 2 was about 70 atomic% of chromium, about 10 atomic% of carbon, and about 20 atomic% of nitrogen. The average content of the upper region of the light-shielding film 2 was about 36 atomic% for chromium, about 40 atomic% for oxygen, about 22 atomic% for nitrogen, and about 2 atomic% for carbon.

The reflectance of the light-shielding film 2 was measured in a state where the surface before forming the resist film 3 described later was exposed. As a result, the reflectance for light having a wavelength of 413 nm was 11.820%, the reflectance for light having a wavelength of 404 nm was 11.695%, and the reflectance for light having a wavelength of 365 nm was 11.894%.
Subsequently, by a spin coating method, a resist film 3 made of a positive resist (THMR-iP3500, manufactured by Tokyo Ohka Kogyo Co., Ltd.) was formed in contact with the surface of the light-shielding film 2 with a target thickness of 290 nm, and the mask of Example 1 was formed. Blank 10 was made.

The film thickness in the transfer pattern forming region of the resist film 3 (the inner region of a quadrangle having a side of 132 mm with respect to the center of the main surface) was measured using a film thickness meter. Specifically, in the transfer pattern forming region, measurement points were set at intervals of 6 mm in a grid pattern, and the film thickness of the resist film 3 was measured at each measurement point. The minimum value d _min of the measured film thickness was 284.2 nm. Further, when the in-plane distribution Δd of the film thickness was measured by subtracting the minimum value from the maximum value of the measured film thickness, it was 4.9 nm, which was 5 nm or less. Further, the reflectance in the transfer pattern forming region of the resist film 3 in the exposure light having a wavelength of 413 nm was measured by a reflectance measuring device. Specifically, in the transfer pattern forming region, measurement points were set at intervals of 6 mm in a grid pattern, and the reflectance of the resist film 3 was measured at each measurement point. The maximum value R _max of the measured reflectance was 2.792%. Further, when the in-plane distribution ΔR of the reflectance was measured by subtracting the minimum value from the maximum value of the measured reflectance, it was 0.352%. When ΔR / Δd [% / nm] was calculated from these results, it was 0.072, which satisfied the condition of 0.1 or less.

[Manufacturing of transfer mask]
Next, the mask blank 10 of Example 1 was separately manufactured by the same procedure, and the transfer mask 20 of Example 1 was manufactured by using the mask blank 10 according to the following procedure. In the separately manufactured mask blank 10, the minimum value d _min of the film thickness of the resist film 3 was 283.9 nm, and the in-plane distribution Δd of the film thickness was 4.9 nm.

First, a transfer pattern to be formed on the light-shielding film 2 was laser-drawn on the resist film 3 with exposure light having a wavelength of 413 nm. The laser-drawn transfer pattern included a line-and-space pattern with a line width of 300 nm. Then, a predetermined development process was performed on the resist film 3 of the mask blank 10 after the laser drawing was performed to form the resist pattern 3a. When the formed resist pattern 3a was observed by a CD-SEM (Critical Dimension-Scanning Electron Microscope), the resist film 3 could resolve the pattern 3a containing a line width narrower than the wavelength of the laser beam of the laser drawing apparatus. It was done. Then, the resist pattern 3a formed on the mask blank 10 was used as a mask, and the light-shielding film 2 was dry-etched. As the dry etching gas, a mixed gas of Cl ₂ and O ₂ (Cl ₂ : O ₂ = 4: 1) was used. After the pattern 2a of the light-shielding film 2 was formed on the substrate 1 by dry etching, the remaining resist pattern 3a was peeled off and removed using hot concentrated sulfuric acid to obtain the transfer mask 20 of Example 1.

When the pattern 2a of the light-shielding film in the transfer mask 20 of Example 1 was observed by CD-SEM, the amount of misalignment from the design pattern was within the permissible range in the plane. Subsequently, the transfer mask 20 of Example 1 is set on the mask stage of the exposure apparatus using the KrF excimer laser as the exposure light, and the KrF exposure light is irradiated from the translucent substrate 1 side of the transfer mask 20. , The pattern was exposed and transferred to the resist film on the semiconductor device. Then, a predetermined treatment was performed on the resist film after the exposure transfer to form a resist pattern, and the resist pattern was observed by CD-SEM. As a result, the amount of misalignment from the design pattern was within the permissible range in the plane. From this result, it can be said that the circuit pattern can be formed on the semiconductor device with high accuracy by using this resist pattern as a mask.

(Comparative Example 1)
[Manufacturing of mask blank]
The mask blank of Comparative Example 1 was manufactured in the same procedure as in Example 1 except for the light-shielding film. The light-shielding film of Comparative Example 1 is also formed by using the same in-line sputtering apparatus as that used in Example 1, and has a composition gradient structure. Specifically, first, the lower region of the light-shielding film containing CrN as a main component was formed with a thickness of 20 nm using Ar gas and N ₂ gas as sputtering gases. Next, Ar gas and CH ₄ gas were used as sputtering gases, and a central region containing CrC as a main component was formed with a thickness of 38 nm. Further, an upper region containing CrON as a main component was formed with a thickness of 15 nm using Ar gas and NO gas as sputtering gases. By the above steps, a light-shielding film was formed on the translucent substrate with a thickness of 73 nm to prepare a mask blank of Comparative Example 1. Central region of the light-shielding film, the N ₂ gas and NO gas used during the formation of the lower region and the upper region includes N (nitrogen), Cr to all of the lower region, middle region, the upper region And N were included. The chromium content of the three regions of the light-shielding film increased in the order of the upper region, the lower region, and the middle region.

The average content of the lower region of the light-shielding film of Comparative Example 1 was about 61 atomic% of chromium, about 32 atomic% of nitrogen, and about 7 atomic% of carbon. The average content of the central region of the light-shielding film was about 71 atomic% for chromium, about 11 atomic% for carbon, and about 18 atomic% for nitrogen. The average content of the upper region of the light-shielding film was about 37 atomic% for chromium, about 41 atomic% for oxygen, about 21 atomic% for nitrogen, and about 1 atomic% for carbon.

Similar to Example 1, the reflectance of the light-shielding film of Comparative Example 1 was measured in a state where the surface before forming the resist film was exposed. As a result, the reflectance for light having a wavelength of 413 nm was 31.165%, the reflectance for light having a wavelength of 404 nm was 29.981%, and the reflectance for light having a wavelength of 365 nm was 26.036%.

Next, in the same manner as in Example 1, a resist film made of a positive resist was formed in contact with the surface of the light-shielding film by a spin coating method with a target thickness of 290 nm, and a mask blank of Comparative Example 1 was prepared. In the same manner as in Example 1, the film thickness in the transfer pattern forming region of the resist film was measured using a film thickness meter. The minimum value d _min of the measured film thickness was 285.0 nm, and the in-plane distribution Δd of the film thickness was 4.8 nm, which was 5 nm or less as in Example 1. Further, in the same procedure as in Example 1, the reflectance in the transfer pattern forming region of the resist film in the exposure light having a wavelength of 413 nm was measured by a reflectance measuring device. The maximum value R _max of the measured reflectance was 1.494%, and the in-plane distribution ΔR of the reflectance was 0.649%. When ΔR / Δd [% / nm] was calculated from these results, it was 0.135, which did not satisfy the condition of 0.1 or less.

[Manufacturing of transfer mask]
Next, the mask blank of Comparative Example 1 was separately manufactured by the same procedure, and the transfer mask of Comparative Example 1 was manufactured by using it in the same procedure as that of Example 1. In the separately manufactured mask blank, the minimum value d _min of the film thickness of the resist film was 284.7 nm, and the in-plane distribution Δd of the film thickness was 4.9 nm. When the formed resist pattern was inspected by CD-SEM, it was not possible to resolve a pattern having a line width narrower than the wavelength of the laser light of the laser drawing apparatus on the resist film. Therefore, as in Example 1, even if dry etching using the formed resist pattern as a mask is performed on the light-shielding film, a desired light-shielding pattern cannot be formed. As described above, using the mask blank of Comparative Example 1, it is not possible to produce a transfer mask having a light-shielding pattern having a line width narrower than the wavelength of the laser beam of the laser drawing apparatus, and a circuit pattern can be produced on the semiconductor device. Could not be formed either.

(Example 2)
[Manufacturing of mask blank]
The mask blank 10 of Example 2 was manufactured in the same procedure as in Example 1 except for the film thickness of the resist film 3. Specifically, the mask blank 10 of Example 2 was produced by contacting the surface of the light-shielding film by a spin coating method to form a resist film made of a positive resist with a target film thickness of 280 nm.

In the same manner as in Example 1, the film thickness in the transfer pattern forming region of the resist film was measured using a film thickness meter. The minimum value d _min of the measured film thickness was 276.6 nm, and the in-plane distribution Δd of the film thickness was 3.3 nm, which was 5 nm or less as in Example 1. Further, in the same procedure as in Example 1, the reflectance in the transfer pattern forming region of the resist film 3 in the exposure light having a wavelength of 404 nm was measured by a reflectance measuring device. The maximum value R _max of the measured reflectance was 2.863%, and the in-plane distribution ΔR of the reflectance was 0.169%. When ΔR / Δd [% / nm] was calculated from these results, it was 0.051, which satisfied the condition of 0.1 or less.

[Manufacturing of transfer mask]
Next, the mask blank 10 of Example 2 was separately manufactured by the same procedure, and the transfer mask 20 of Example 2 was manufactured using the mask blank 10 by the same procedure as that of Example 1. However, in Example 2, a transfer pattern was drawn on the resist film 3 using a laser beam having a wavelength of 404 nm. In the separately manufactured mask blank, the minimum value d _min of the film thickness of the resist film was 276.9 nm, and the in-plane distribution Δd of the film thickness was 3.5 nm.

When the resist pattern 3a formed through the laser drawing step and the developing step was inspected by CD-SEM, a pattern having a line width narrower than the wavelength of the laser beam of the laser drawing device could be resolved on the resist film. .. Dry etching using the resist pattern 3a as a mask was performed on the light-shielding film 2 to manufacture the transfer mask 20 of Example 2.

When the pattern 2a of the light-shielding film in the transfer mask 20 of Example 2 was observed by CD-SEM, the amount of misalignment from the design pattern was within the permissible range in the plane. Subsequently, the transfer mask 20 of the second embodiment is set on the mask stage of the exposure apparatus using the KrF excimer laser as the exposure light, and the KrF exposure light is irradiated from the translucent substrate 1 side of the transfer mask 20. , The pattern was exposed and transferred to the resist film on the semiconductor device. Then, a predetermined treatment was performed on the resist film after the exposure transfer to form a resist pattern, and the resist pattern was observed by CD-SEM. As a result, the amount of misalignment from the design pattern was within the permissible range in the plane. From this result, it can be said that the circuit pattern can be formed on the semiconductor device with high accuracy by using this resist pattern as a mask.

(Comparative Example 2)
[Manufacturing of mask blank]
The mask blank of Comparative Example 2 was manufactured in the same procedure as in Comparative Example 1 except for the film thickness of the resist film. Specifically, a resist film made of a positive resist was formed in contact with the surface of the light-shielding film by a spin coating method with a target thickness of 280 nm, and a mask blank of Comparative Example 2 was prepared.

Similar to Example 2, the film thickness in the transfer pattern forming region of the resist film was measured using a film thickness meter. The minimum value d _min of the measured film thickness was 275.6 nm, and the in-plane distribution Δd of the film thickness was 3.2 nm, which was 5 nm or less as in Example 2. Further, in the same procedure as in Example 2, the reflectance in the transfer pattern forming region of the resist film in the exposure light having a wavelength of 404 nm was measured by a reflectance measuring device. The maximum value R _max of the measured reflectance was 1.239%, and the in-plane distribution ΔR of the reflectance was 0.799%. When ΔR / Δd [% / nm] was calculated from these results, it was 0.250, which did not satisfy the condition of 0.1 or less.

[Manufacturing of transfer mask]
Next, the mask blank of Comparative Example 2 was separately manufactured by the same procedure, and the transfer mask of Comparative Example 2 was manufactured by using it in the same procedure as in Example 1. In Comparative Example 2, a transfer pattern was drawn on the resist film using a laser beam having a wavelength of 404 nm. In the separately manufactured mask blank, the minimum value d _min of the film thickness of the resist film was 275.8 nm, and the in-plane distribution Δd of the film thickness was 3.3 nm.

When the resist pattern formed through the laser drawing step and the developing step was inspected by CD-SEM, it was not possible to resolve the pattern having a line width narrower than the wavelength of the laser beam of the laser drawing device on the resist film. .. Therefore, as in Example 1, even if dry etching using the formed resist pattern as a mask is performed on the light-shielding film, a desired light-shielding pattern cannot be formed. As described above, using the mask blank of Comparative Example 2, it is not possible to produce a transfer mask having a light-shielding pattern having a line width narrower than the wavelength of the laser light of the laser drawing apparatus, and a circuit pattern can be produced on the semiconductor device. Could not be formed either.

(Example 3)
[Manufacturing of mask blank]
The mask blank 10 of Example 3 was manufactured in the same procedure as in Example 1 except for the film thickness of the resist film 3. Specifically, the mask blank 10 of Example 3 was produced by contacting the surface of the light-shielding film by a spin coating method to form a resist film made of a positive resist with a target film thickness of 260 nm.

In the same manner as in Example 1, the film thickness in the transfer pattern forming region of the resist film was measured using a film thickness meter. The minimum value d _min of the measured film thickness was 260.7 nm, and the in-plane distribution Δd of the film thickness was 4.9 nm, which was 5 nm or less as in Example 1. Further, in the same procedure as in Example 1, the reflectance in the transfer pattern forming region of the resist film 3 in the exposure light having a wavelength of 365 nm was measured by a reflectance measuring device. The maximum value R _max of the measured reflectance was 3.206%, and the in-plane distribution ΔR of the reflectance was 0.364%. When ΔR / Δd [% / nm] was calculated from these results, it was 0.074, which satisfied the condition of 0.1 or less.

[Manufacturing of transfer mask]
Next, the mask blank 10 of Example 3 was separately manufactured by the same procedure, and the transfer mask 20 of Example 3 was manufactured using the mask blank 10 by the same procedure as that of Example 1. However, in Example 3, a transfer pattern was drawn on the resist film 3 using a laser beam having a wavelength of 365 nm. In the separately manufactured mask blank, the minimum value d _min of the film thickness of the resist film was 260.5 nm, and the in-plane distribution Δd of the film thickness was 4.8 nm.

When the resist pattern 3a formed through the laser drawing step and the developing step was inspected by CD-SEM, a pattern having a line width narrower than the wavelength of the laser beam of the laser drawing device could be resolved on the resist film. .. Dry etching using the resist pattern 3a as a mask was performed on the light-shielding film 2 to manufacture the transfer mask 20 of Example 3.

When the pattern 2a of the light-shielding film in the transfer mask 20 of Example 3 was observed by CD-SEM, the amount of misalignment from the design pattern was within the permissible range in the plane. Subsequently, the transfer mask 20 of Example 3 is set on the mask stage of the exposure apparatus using the KrF excimer laser as the exposure light, and the KrF exposure light is irradiated from the translucent substrate 1 side of the transfer mask 20. , The pattern was exposed and transferred to the resist film on the semiconductor device. Then, a predetermined treatment was performed on the resist film after the exposure transfer to form a resist pattern, and the resist pattern was observed by CD-SEM. As a result, the amount of misalignment from the design pattern was within the permissible range in the plane. From this result, it can be said that the circuit pattern can be formed on the semiconductor device with high accuracy by using this resist pattern as a mask.

(Comparative Example 3)
[Manufacturing of mask blank]
The mask blank of Comparative Example 3 was manufactured in the same procedure as in Comparative Example 1 except for the film thickness of the resist film. Specifically, a resist film made of a positive resist was formed in contact with the surface of the light-shielding film by a spin coating method with a target film thickness of 260 nm to prepare a mask blank of Comparative Example 3.

In the same manner as in Example 3, the film thickness in the transfer pattern forming region of the resist film was measured using a film thickness meter. The minimum value d _min of the measured film thickness was 261.1 nm, and the in-plane distribution Δd of the film thickness was 4.8 nm, which was 5 nm or less as in Example 2. Further, in the same procedure as in Example 2, the reflectance in the transfer pattern forming region of the resist film in the exposure light having a wavelength of 365 nm was measured by the reflectance measuring device. The maximum value R _max of the measured reflectance was 6.440%, and the in-plane distribution ΔR of the reflectance was 2.344%. When ΔR / Δd [% / nm] was calculated from these results, it was 0.488, which did not satisfy the condition of 0.1 or less.

[Manufacturing of transfer mask]
Next, the mask blank of Comparative Example 3 was separately manufactured by the same procedure, and the transfer mask of Comparative Example 3 was manufactured by using it in the same procedure as in Example 1. In Comparative Example 3, a transfer pattern was drawn on the resist film using a laser beam having a wavelength of 365 nm. In the separately manufactured mask blank, the minimum value d _min of the film thickness of the resist film was 260.7 nm, and the in-plane distribution Δd of the film thickness was 4.7 nm.

When the resist pattern formed through the laser drawing step and the developing step was inspected by CD-SEM, it was not possible to resolve the pattern having a line width narrower than the wavelength of the laser beam of the laser drawing device on the resist film. .. Therefore, as in Example 1, even if dry etching using the formed resist pattern as a mask is performed on the light-shielding film, a desired light-shielding pattern cannot be formed. As described above, using the mask blank of Comparative Example 2, it is not possible to produce a transfer mask having a light-shielding pattern having a line width narrower than the wavelength of the laser beam of the laser drawing apparatus, and the circuit pattern is formed on the semiconductor device. Could not be formed either.

On the other hand, a plurality of translucent substrates different from those in Example 1 are prepared, a light-shielding film is formed under the same film-forming conditions as in Example 1, and a plurality of mask blanks are formed by changing only the film thickness of the resist film. Was formed. Similarly, a plurality of translucent substrates different from those of Comparative Example 1 are prepared, a light-shielding film is formed under the same film-forming conditions as in Comparative Example 1, and a plurality of masks are formed by changing only the film thickness of the resist film. A blank was formed. Then, the reflectance at a predetermined exposure wavelength was measured for a plurality of mask blanks corresponding to Example 1 and Comparative Example 1, respectively. FIG. 3 is a graph showing the relationship between the reflectance and the resist film thickness at the exposure wavelength of 413 nm of the mask blanks corresponding to Example 1 and Comparative Example 1. Further, FIG. 4 is a graph showing the relationship between the reflectance and the resist film thickness of the mask blanks corresponding to Example 1 and Comparative Example 1 at an exposure wavelength of 404 nm. As can be seen in FIGS. 3 and 4, at any exposure wavelength, the mask blank corresponding to Comparative Example 1 has a reflectance with respect to the resist film thickness more than the mask blank corresponding to Example 1. The fluctuation range is large. From these facts, in the mask blank 10 of Example 1, even if the film thickness and the exposure wavelength of the resist film 3 are changed, a pattern having a line width narrower than the wavelength of the laser light of the laser drawing apparatus is solved in the resist film. It is expected that it can be imaged. On the other hand, in the mask blank of Comparative Example 1, even if the film thickness and the exposure wavelength of the resist film are changed, a pattern having a line width narrower than the wavelength of the laser light of the laser drawing apparatus cannot be resolved on the resist film. Is expected.

Although the present invention has been described above with reference to preferred examples, the present invention is not limited to the above examples.

1 ... translucent substrate, 2 ... light-shielding film, 2a ... light-shielding pattern (transfer pattern), 3 ... resist film,
3a ... resist pattern, 10 ... mask blank, 20 ... transfer mask

Claims (14)

A mask blank having a structure in which a thin film for forming a transfer pattern and a resist film are laminated in this order on a substrate.
The thin film is made of a material containing a metal element.
The in-plane distribution of the reflectance with respect to the exposure light in the transfer pattern forming region on the surface of the resist film is ΔR [%], and the in-plane distribution of the film thickness in the transfer pattern forming region of the resist film is Δd [nm]. When, ΔR / Δd [% / nm] is 0.1 or less, and Δd [nm] is larger than zero.
A mask blank characterized in that the wavelength of the exposure light is a wavelength selected from a wavelength region of 350 nm or more and 420 nm or less. The mask blank according to claim 1, wherein the in-plane distribution ΔR of the reflectance is 0.4% or less. The mask blank according to claim 1 or 2, wherein the reflectance of the resist film with respect to the exposure light is 5% or less. The mask blank according to any one of claims 1 to 3, wherein the transfer pattern forming region is an inner region of a square having a side of 132 mm with respect to the center of the substrate. The mask blank according to any one of claims 1 to 4, wherein the in-plane distribution of the film thickness of the resist film in the transfer pattern forming region is 5 nm or less. The mask blank according to any one of claims 1 to 5, wherein the wavelength of the exposure light is a wavelength selected from a wavelength region of 400 nm or more and 420 nm or less. The thickness of the resist film is characterized in that it is in the range of 260 nm or more and 290 nm or less, 320 nm or more and 350 nm or less, 385 nm or more and 415 nm or less, or 445 nm or more and 475 nm or less. The mask blank according to claim 6. The mask blank according to any one of claims 1 to 7, wherein the resist film is made of a material that is exposed to exposure light in the wavelength region. The mask blank according to any one of claims 1 to 8, wherein the thin film is made of a material containing chromium. The mask blank according to claim 9, wherein the thin film is a composition gradient film in which the content of chromium changes in the thickness direction. The mask blank according to any one of claims 1 to 10, wherein the thin film is a light-shielding film having an optical density of 3 or more with respect to the exposure light. A method for producing a transfer mask using the mask blank according to any one of claims 1 to 11.
A step of exposing the resist film with the transfer pattern with the exposure light and then performing a developing process to form a resist film having the transfer pattern.
A method for producing a transfer mask, which comprises a step of forming a transfer pattern on the thin film by etching using a resist film having the transfer pattern as a mask. The method for producing a transfer mask according to claim 12, wherein the step of forming the transfer pattern on the thin film is to form the transfer pattern on the thin film by dry etching using a gas containing chlorine. A method for manufacturing a semiconductor device, which comprises a step of exposing and transferring a transfer pattern to a resist film on a semiconductor substrate using the transfer mask manufactured by the method for manufacturing a transfer mask according to claim 12 or 13.

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