JP6678269B2 - Reflective mask blank and reflective mask - Google Patents

Description

  The present invention relates to a reflective mask blank and a reflective mask that can be used for manufacturing a highly integrated semiconductor device.

  In the semiconductor industry, in response to the high integration of semiconductor devices, the exposure wavelength of the light source of the exposure device used for manufacturing the semiconductor devices is g-line of 436 nm, i-line of 365 nm, KrF laser of 248 nm, It becomes shorter gradually with the 193 nm ArF laser. In order to realize finer pattern transfer, EUV lithography, which is an exposure technique using Extreme Ultra Violet (hereinafter, referred to as “EUV”) light, has been proposed. Here, the EUV light refers to light in a wavelength band in a soft X-ray region or a vacuum ultraviolet region, and specifically, light having a wavelength of about 0.2 to 100 nm. As the EUV light, for example, one having a wavelength of about 13.5 nm can be used.

  In EUV lithography, a reflective mask is used because the difference in absorptivity between materials for EUV light is small. As a reflective mask, for example, a multilayer reflective film that reflects exposure light is formed on a substrate, and a phase shift film that absorbs exposure light is formed in a pattern on a protective film for protecting the multilayer reflective film. The formed one has been proposed. Light incident on a reflective mask mounted on an exposure device (pattern transfer device) is absorbed by a portion having a phase shift film pattern, and is reflected by a multilayer reflective film at a portion having no phase shift film pattern. The image is transferred onto the semiconductor substrate through the reflection optical system. Part of the exposure light that is incident on the phase shift film pattern is reflected with a phase difference of about 180 degrees from the light reflected by the multilayer reflective film (phase shift). To get contrast.

  Techniques related to such a reflective mask for EUV lithography and a reflective mask blank for manufacturing the same are disclosed in Patent Documents 1 to 3, for example.

  Further, in Patent Document 4, a light semi-transmissive film is provided on a transparent substrate, and the center line average roughness of an entrance / exit surface of the light semi-transmissive film with respect to exposure light (specified in JIS B 0601, nmRa ) Of 0.1 to 50 nmRa is disclosed.

JP-A-2004-207593 JP 2009-212220 A JP 2010-080659 A JP-A-11-237727

  In the case of a reflection type mask having a phase shift film for absorbing exposure light, light beams having inverted phase differences near 180 degrees interfere with each other at the edge of the phase shift film pattern, so that the image contrast of the projection optical image is increased. Is improved. And, with the improvement of the image contrast, the resolution of the pattern transfer is also improved.

  In order to obtain high contrast at the edge of the phase shift film pattern, it is advantageous that the absolute reflectance of the phase shift film with respect to EUV light is high. For example, the phase shift film can be designed so that the absolute reflectance for EUV light is 1 to 6%. However, if the surface of the phase shift film has irregularities, the reflected light is scattered on the surface of the phase shift film, causing a problem that the absolute reflectance decreases. Note that, relative to the absolute reflectance, the relative reflectance is the reflectance of the phase shift film to EUV light with reference to the absolute reflectance when EUV light is directly incident on the multilayer reflective film and reflected. It is.

  Further, the control of the unevenness on the surface of the phase shift film is performed by a conventional method, for example, as described in Patent Document 4, by setting the center line average roughness of the input / output surface of the light semi-transmissive film to the exposure light to a predetermined value. The method of setting the range alone is not enough to avoid the above-described decrease in the absolute reflectance.

  Therefore, in the present invention, when the phase shift film is designed so that the absolute reflectance with respect to UV light is within a predetermined range, the difference (deviation) from the design value is reduced, and the absolute reflectance is within a high predetermined range. An object of the present invention is to provide a reflection type mask capable of obtaining a high contrast at an edge portion of a phase shift film pattern by obtaining a phase shift film. It is another object of the present invention to provide a reflective mask blank capable of obtaining a high contrast at an edge of a phase shift film pattern.

  In order to solve the above-mentioned problems, the present inventors have conducted intensive studies. As a result, the roughness of a predetermined spatial frequency (or spatial wavelength) component with respect to the wavelength of EUV light affects the phase shift film. It has been found that a decrease in the absolute reflectance with respect to UV light occurs. Based on the knowledge, the present inventors have found that among the roughness (irregularity) components on the surface of the phase shift film, a roughness component which has an effect on a decrease in the absolute reflectance of the phase shift film with respect to UV light is described. The present inventors have found that by specifying the spatial frequency and managing the amplitude intensity at this spatial frequency, it is possible to avoid a decrease in the absolute reflectance of the phase shift film with respect to the UV light, and thus the present invention.

  In the case of a reflective mask, attempts have been made to reduce the surface roughness of the reflective mask. It has not been known at all that the roughness of the spatial frequency (or spatial wavelength) component has an effect.

  Therefore, in order to solve the above problem, the present invention has the following configuration. The present invention provides a reflective mask blank characterized by the following constitutions 1 to 4, and a reflective mask characterized by the following constitutions 5 to 8.

(Configuration 1)
Configuration 1 of the present invention is a reflective mask blank in which a multilayer reflective film and a phase shift film for shifting the phase of EUV light are formed in this order on a substrate, and a 1 μm × 1 μm area on the surface of the phase shift film. Wherein the root mean square roughness (Rms) obtained by measurement with an atomic force microscope is 0.50 nm or less, and the power spectrum density at a spatial frequency of 10 to 100 μm ⁻¹ is 17 nm ⁴ or less. This is a reflective mask blank.

  According to the configuration 1 of the present invention, in the phase shift film of the reflective mask blank, the predetermined root-mean-square roughness (Rms) and the power spectrum density of the predetermined spatial frequency are set in the predetermined range, whereby the phase shift film is formed. Is designed to have a predetermined range in which the absolute reflectance with respect to UV light is high, the difference (deviation) from the design value is reduced, and the phase shift film is in a predetermined range where the absolute reflectance with respect to EUV light is high. be able to. As a result, it is possible to obtain a reflective mask blank for manufacturing a reflective mask capable of obtaining a high contrast at the edge of the phase shift film pattern.

(Configuration 2)
A second aspect of the present invention is the reflective mask blank according to the first aspect, wherein a protective film is formed on the multilayer reflective film.

  According to the configuration 2 of the present invention, since the reflective mask blank has the protective film on the multilayer reflective film, it is possible to suppress damage to the multilayer reflective film surface when manufacturing a transfer mask (EUV mask). As a result, the reflectance characteristics of EUV light of a reflective mask manufactured using the reflective mask blank are further improved.

(Configuration 3)
Configuration 3 of the present invention is characterized in that the phase shift film has a tantalum-based material layer containing tantalum and nitrogen, and a chromium-based material layer containing chromium and nitrogen on the tantalum-based material layer. Or the reflective mask blank according to 2.

  According to the third aspect of the present invention, the phase shift film includes a tantalum-based material layer containing tantalum and nitrogen, and a chromium-based material layer containing chromium and nitrogen on the tantalum-based material layer. A phase shift film having a high absolute reflectance with respect to UV light while having a phase shift effect can be obtained.

(Configuration 4)
A fourth aspect of the present invention is the reflective mask blank according to the third aspect, wherein the chromium-based material layer has a thickness of 5 nm or more and 30 nm or less.

  According to the fourth aspect of the present invention, an oxide layer (tantalum oxide layer) is formed on the surface of the tantalum-based material layer by setting the thickness of the chromium-based material layer covering the tantalum-based material layer to a predetermined range. Can be prevented.

(Configuration 5)
Configuration 5 of the present invention is a reflective mask in which a multilayer reflective film and a phase shift film pattern for shifting the phase of EUV light are formed on a substrate in this order, and the 1 μm × 1 μm In the region, a root-mean-square roughness (Rms) obtained by measurement with an atomic force microscope is 0.50 nm or less, and a power spectrum density at a spatial frequency of 10 to 100 μm ⁻¹ is 17 nm ⁴ or less. Is a reflection type mask.

  According to the fifth aspect of the present invention, when the phase shift film of the reflective mask is designed so that the absolute reflectance with respect to UV light is within a predetermined range, the difference (deviation) from the design value is small and the absolute value with respect to EUV light is small. By providing a phase shift film having a high reflectance in a predetermined range, it is possible to obtain a reflective mask capable of obtaining a high contrast at an edge portion of the phase shift film pattern.

(Configuration 6)
Configuration 6 of the present invention is the reflection type mask according to Configuration 5, wherein a protective film is formed on the multilayer reflective film.

  According to the sixth aspect of the present invention, since the reflective mask blank has the protective film on the multilayer reflective film, it is possible to suppress damage to the multilayer reflective film surface when manufacturing the reflective mask (EUV mask). For this reason, it is preferable that the reflective mask blank also has a protective film on the multilayer reflective film in the reflective mask.

(Configuration 7)
Configuration 7 of the present invention is that, in a 1 μm × 1 μm region on the surface of the multilayer reflective film or the protective film, a root-mean-square roughness (Rms) obtained by measurement with an atomic force microscope is 0.15 nm or less, and The reflective mask according to Configuration 5 or 6, wherein the power spectrum density at a spatial frequency of 10 to 100 μm ⁻¹ is 7 nm ⁴ or less.

  According to the seventh aspect of the present invention, in a predetermined area on the surface of the multilayer reflective film or the protective film, a predetermined root-mean-square roughness (Rms) and a power spectral density at a predetermined spatial frequency are set to a predetermined range, thereby achieving UV irradiation. Since a phase shift film having a higher absolute reflectance with respect to light can be obtained, the intensity of exposure light at the time of exposure for manufacturing a semiconductor device can be increased. Therefore, the throughput at the time of manufacturing the semiconductor device can be improved.

(Configuration 8)
Configuration 8 of the present invention, configured characterized in that the power spectral density of the phase shift film pattern surface, the difference between the power spectral density in the multilayer reflective film or the protective film surface is 10 nm ⁴ or less 5-7 Is a reflection type mask.

  According to the eighth aspect of the present invention, it is possible to more reliably obtain a reflection type mask capable of obtaining a high contrast at the edge of the phase shift film pattern because the difference of the predetermined power spectrum density is within the predetermined range. Can be.

  According to the present invention, when the phase shift film is designed so that the absolute reflectance with respect to UV light falls within a predetermined range, the difference (deviation) from the design value is reduced to achieve a high absolute reflectance in a predetermined range. Since a certain phase shift film can be obtained, it is possible to obtain a reflective mask capable of obtaining high contrast at the edge of the phase shift film pattern. Further, according to the present invention, it is possible to obtain a reflective mask blank capable of obtaining high contrast at the edge of the phase shift film pattern.

FIG. 1A is a perspective view showing a mask blank substrate according to one embodiment of the present invention. FIG. 1B is a schematic cross-sectional view illustrating a mask blank substrate of the present embodiment. It is a cross section showing an example of composition of a substrate with a multilayer reflective film concerning one embodiment of the present invention. It is a cross section showing an example of the composition of the reflective mask blank concerning one embodiment of the present invention. It is a cross section showing an example of the reflective mask concerning one embodiment of the present invention. It is a cross section showing another example of composition of a reflective mask blank concerning one embodiment of the present invention. 9 is a graph showing the results of power spectrum analysis of the phase shift film surfaces of the reflective mask blanks of Example 3 of the present invention and Comparative Example 1.

  The present invention is a reflective mask blank having a multilayer reflective film and a phase shift film in which high refractive index layers and low refractive index layers are alternately laminated on a main surface of a mask blank substrate.

  FIG. 5 is a schematic view showing an example of the reflective mask blank 30 of the present invention. The reflective mask blank 30 of the present invention has a mask blank multilayer film 26 including a multilayer reflective film 21 and a phase shift film 24 on the main surface of the mask blank substrate 10. In the present specification, the multilayer film 26 for a mask blank includes the multilayer reflective film 21 and the phase shift film 24 that are formed by being stacked on the main surface of the substrate 10 for a mask blank in the reflective mask blank 30. There are multiple films. The mask blank multilayer film 26 may further include a protective film 22 formed between the multilayer reflective film 21 and the phase shift film 24, and / or an etching mask film 25 formed on the surface of the phase shift film 24. it can. In the case of the reflective mask blank 30 shown in FIG. 5, the mask blank multilayer film 26 on the main surface of the mask blank substrate 10 is composed of the multilayer reflective film 21, the protective film 22, the phase shift film 24, and the etching mask film. 25.

  In this specification, “having the mask blank multilayer film 26 on the main surface of the mask blank substrate 10” means that the mask blank multilayer film 26 is arranged in contact with the surface of the mask blank substrate 10. In addition to the case where it means that there is another film between the mask blank substrate 10 and the mask blank multilayer film 26. In this specification, for example, “the film A is disposed in contact with the surface of the film B” means that the film A and the film B are not interposed between the film A and the film B without any other film interposed therebetween. It means that they are arranged so as to be in direct contact with each other.

  FIG. 3 is a schematic view showing another example of the reflective mask blank 30 of the present invention. In the case of the reflective mask blank 30 of FIG. 3, the mask blank multilayer film 26 has the multilayer reflective film 21, the protective film 22, and the phase shift film 24, but does not have the etching mask film 25. .

The reflective mask blank 30 of the present invention is a reflective mask blank in which a multilayer reflective film and a phase shift film for shifting the phase of EUV light are formed in this order on a substrate. In the reflective mask blank 30 of the present invention, the root mean square roughness (Rms) obtained by measurement with an atomic force microscope in the 1 μm × 1 μm region on the surface of the phase shift film 24 is 0.50 nm or less, and the space The power spectrum density at a frequency of 10 to 100 μm ⁻¹ is 17 nm ⁴ or less.

  When using the reflective mask blank 30 of the present invention to design the phase shift film 24 so that the absolute reflectance of the phase shift film 24 with respect to UV light is within a predetermined range, the difference (deviation) from the design value is small and high. Since the phase shift film 24 having the absolute reflectance in the range can be obtained, it is possible to manufacture the reflective mask 40 that can obtain high contrast at the edge of the phase shift film pattern 27.

  Next, surface roughness (Rmax, Rms) and power spectrum density (PSD) which are parameters indicating the surface morphology of the phase shift film 24 will be described below.

  First, Rms (Root means square), which is a typical index of surface roughness, is root mean square roughness, and is a square root of a value obtained by averaging the squares of deviations from an average line to a measurement curve. Rms is represented by the following equation (1).

In the equation (1), 1 is a reference length, and Z is a height from the average line to the measurement curve.

  Similarly, Rmax, which is a representative index of surface roughness, is the maximum height of the surface roughness, and the difference between the absolute value of the maximum value of the peak height and the maximum value of the valley depth of the roughness curve. (Difference between the highest mountain and the deepest valley).

  Rms and Rmax are conventionally used for managing the surface roughness of the mask blank substrate 10, and are excellent in that the surface roughness can be grasped numerically. However, both Rms and Rmax are height information, and do not include information on minute changes in surface shape.

  On the other hand, by converting the obtained surface irregularities into the spatial frequency domain, the power spectrum analysis represented by the amplitude intensity at the spatial frequency can digitize a fine surface shape. Assuming that Z (x, y) is height data at the x coordinate and the y coordinate, the Fourier transform is given by the following equation (2).

  Here, Nx and Ny are the numbers of data in the x and y directions. u = 0, 1, 2,... Nx-1, v = 0, 1, 2,... Ny-1, and the spatial frequency f is given by the following equation (3).

Here, in equation (3), dx is the minimum resolution in the x direction, and dy is the minimum resolution in the y direction.

The power spectrum density PSD at this time is given by the following equation (4).

  This power spectrum analysis is excellent in that a change in the surface state of the phase shift film 24 of the reflective mask blank 30 can be grasped not only as a change in the height but also as a change in the spatial frequency. This is a technique for analyzing the effect of microscopic reactions at the atomic level on the surface.

When evaluating the surface state of the phase shift film of the reflective mask blank 30 by power spectrum analysis, the integral value I of the power spectrum density (PSD) can be used. The integral value I means the area of a predetermined spatial frequency range drawn by the value of the power spectral density (PSD) with respect to the spatial frequency as exemplified in FIG. 6, and is defined as Expression (5).

The spatial frequency f is defined as in equation (3), and the power spectral density is uniquely calculated as a function of the spatial frequency determined by the values of u and ν. Here, in order to calculate the power spectrum density for discrete spatial frequencies, when the measurement area and the number of data points are equal in the x direction and the y direction, the spatial frequency f _i is defined as in equation (6). Here, X ′ and N ′ are the measurement area and the number of data points. P _{(f i)} is the power spectral density in the spatial frequency _{f i.}

Then, in the reflective mask blank 30 of the present invention, in order to achieve the above object, the surface of the phase shift film 24 is formed by using the above-mentioned surface roughness (Rms) and power spectrum density to form a 1 μm × 1 μm region. The root-mean-square roughness (Rms) obtained by measurement with an atomic force microscope is 0.50 nm or less, and the power spectrum density at a spatial frequency of 10 to 100 μm ⁻¹ is 17 nm ⁴ or less.

  In the present invention, the area of 1 μm × 1 μm on the surface of the phase shift film 24 may be any part of the transfer pattern formation area. When the mask blank substrate 10 has a size of 6025 (152 mm × 152 mm × 6.35 mm), the transfer pattern formation region is, for example, a region of 142 mm × 142 mm excluding the peripheral region of the surface of the reflective mask blank 30 or 132 mm × The area may be a 132 mm area or a 132 mm × 104 mm area. The arbitrary location may be, for example, a central area on the surface of the reflective mask blank 30.

  In the present invention, the area of 1 μm × 1 μm can be a center area of the film surface of the phase shift film 24. For example, when the film surface of the phase shift film 24 of the reflective mask blank 30 has a rectangular shape, the center is an intersection of diagonal lines of the rectangle. That is, the intersection point and the center of the region (the center of the region is the same as the center of the film surface) match.

  In addition, the 1 μm × 1 μm region, the transfer pattern formation region, and an arbitrary portion described above can be applied to the mask blank substrate 10 and the multilayer reflective film-attached substrate 20 in some cases.

Further, the power spectrum density at a spatial frequency of 10 to 100 μm ⁻¹ obtained by measuring an area of 1 μm × 1 μm on the surface of the phase shift film 24 of the reflective mask blank 30 with an atomic force microscope is set to 17 nm ⁴ or less. Preferably, the power spectrum density at a spatial frequency of 10 to 100 μm ⁻¹ is 14 nm ⁴ or less, more preferably, the power spectrum density at a spatial frequency of 10 to 100 μm ⁻¹ is 10 nm ⁴ or less.

  Further, the root mean square roughness (Rms) is desirably 0.50 nm or less, preferably 0.45 nm or less, more preferably 0.40 nm or less, and still more preferably 0.36 nm or less. Further, the maximum height (Rmax) is preferably 5 nm or less, more preferably 4.5 nm or less, further preferably 4 nm or less, and more preferably 3.5 nm or less.

In addition, in the reflective mask blank 30 of the present invention, in order to achieve the above object, the surface of the multilayer film 26 for a mask blank has a spatial frequency of 10 μm × 1 μm obtained by measuring an area of 1 μm × 1 μm with an atomic force microscope. More preferably, the integrated value I of the power spectrum density of 100 μm ⁻¹ is 360 nm ³ or less. More preferably, the integral value I is desirably 300 nm ³ or less. Particularly preferably, the integral value I is desirably 250 nm ³ or less.

  When the reflective mask blank 30 of the present invention is used to design the phase shift film 24 so that the absolute reflectance of the phase shift film 24 with respect to UV light is within a predetermined range, the difference (deviation) from the design value is reduced. Since the phase shift film 24 having a high absolute reflectance in a predetermined range can be obtained, it is possible to manufacture the reflective mask 40 that can obtain high contrast at the edge of the phase shift film pattern 27.

  Next, the reflective mask blank 30 of the present invention will be specifically described.

[Mask blank substrate 10]
First, a mask blank substrate 10 that can be used for manufacturing the reflective mask blank 30 of the present invention will be described below.

  FIG. 1A is a perspective view showing an example of a mask blank substrate 10 that can be used for manufacturing the reflective mask blank 30 of the present invention. FIG. 1B is a schematic cross-sectional view of the mask blank substrate 10 shown in FIG.

  The mask blank substrate 10 (or simply referred to as “substrate 10” or “glass substrate 10” in some cases) is a rectangular plate-like body, and has two opposing main surfaces 2 and an end surface 1. . The two opposing main surfaces 2 are an upper surface and a lower surface of the plate-like body, and are formed so as to oppose each other. At least one of the two opposing main surfaces 2 is a main surface on which a transfer pattern is to be formed.

  The end face 1 is a side face of the plate-shaped body and is adjacent to the outer edge of the opposing main surface 2. The end face 1 has a flat end face part 1d and a curved end face part 1f. The planar end surface portion 1d is a surface connecting the side of one opposing main surface 2 and the side of the other opposing main surface 2, and includes a side surface portion 1a and a chamfered inclined surface portion 1b. The side surface portion 1a is a portion (T surface) substantially perpendicular to the opposing main surface 2 in the planar end surface portion 1d. The chamfered slope portion 1b is a chamfered portion (C surface) between the side surface portion 1a and the opposing main surface 2, and is formed between the side surface portion 1a and the opposing main surface 2.

  The curved end surface portion 1f is a portion (R portion) adjacent to the vicinity of a corner 10a of the substrate 10 when the substrate 10 is viewed in a plan view, and includes a side surface portion 1c and a chamfered inclined surface portion 1e. Here, viewing the substrate 10 in a plan view means, for example, viewing the substrate 10 from a direction perpendicular to the opposing main surface 2. The corner 10 a of the substrate 10 is, for example, near the intersection of two sides at the outer edge of the opposing main surface 2. The intersection of the two sides may be the intersection of the respective extension lines of the two sides. In this example, the curved end face portion 1f is formed in a curved shape by rounding a corner 10a of the substrate 10.

  In order to more reliably achieve the object of the present invention, the main surface of the mask blank substrate 10 used for the reflective mask blank 30 of the present invention and the surface of the multilayer reflective film 21 of the substrate 20 with a multilayer reflective film are required to have a predetermined shape. It is preferable to have a surface roughness of

  In addition, it is preferable that the main surface of the mask blank substrate 10 is a surface processed by catalyst-based etching. Catalyst Referred Etching (hereinafter also referred to as CARE) refers to placing a workpiece (mask blank substrate) and a catalyst in a processing solution or supplying a processing solution between the workpiece and the catalyst. This is a surface processing method in which a workpiece is brought into contact with a catalyst, and the workpiece is processed by active species generated from molecules in a processing solution adsorbed on the catalyst at that time. When the workpiece is made of a solid oxide such as glass, the treatment liquid is water, and the workpiece and the catalyst are brought into contact with each other in the presence of water to cause relative movement between the catalyst and the surface of the workpiece. By doing so, a decomposition product due to hydrolysis is removed from the surface of the workpiece to be processed.

  The main surface of the mask blank substrate 10 is selectively surface-processed by catalyst reference etching from a convex portion that comes into contact with the catalyst surface as a reference surface. Therefore, the unevenness (surface roughness) constituting the main surface becomes a very uniform surface form while maintaining extremely high smoothness, and the ratio of the concave portion to the reference surface is smaller than that of the convex portion. It has many surface morphologies. Therefore, when a plurality of thin films are laminated on the main surface, the defect size on the main surface tends to be small. Therefore, it is preferable in terms of defect quality to perform the surface treatment by the catalyst-based etching. In particular, an effect is particularly exhibited when a multilayer reflective film 21 described later is formed on the main surface. In addition, by performing the surface treatment on the main surface by the catalyst-based etching as described above, the surface having the above-described predetermined range of surface roughness and predetermined power spectral density can be formed relatively easily.

  When the material of the substrate 10 is a glass material, at least one material selected from the group consisting of platinum, gold, transition metals, and alloys containing at least one of them can be used as the catalyst. Further, as the treatment liquid, at least one kind of liquid selected from the group consisting of functional water such as pure water, ozone water and hydrogen water, a low-concentration alkaline aqueous solution, and a low-concentration acidic aqueous solution can be used.

  The mask blank substrate 10 used for the reflective mask blank 30 of the present invention has a main surface on the side where a transfer pattern is formed, which is subjected to surface processing so as to have high flatness from the viewpoint of obtaining at least pattern transfer accuracy and positional accuracy. Is preferred. In the case of the EUV reflective mask blank substrate 10, the flatness is 0.1 μm or less in a 132 mm × 132 mm region or a 142 mm × 142 mm region of the main surface on the side where the transfer pattern of the substrate 10 is formed. Is more preferable, and particularly preferably 0.05 μm or less. More preferably, the flatness is 0.03 μm or less in a region of 132 mm × 132 mm on the main surface of the substrate 10 on which the transfer pattern is formed. The main surface opposite to the side on which the transfer pattern is formed is a surface to be electrostatically chucked when set in an exposure apparatus, and has a flatness of 1 μm or less, particularly preferably in a 142 mm × 142 mm area. It is 0.5 μm or less.

As a material of the reflective mask blank substrate 10 for EUV exposure, any material having low thermal expansion characteristics may be used. For example, SiO ₂ —TiO ₂ based glasses (binary (SiO ₂ —TiO ₂ ) and ternary (SiO ₂ —TiO ₂ —SnO ₂ )) having low thermal expansion characteristics, for example, SiO ₂ —Al ₂ O A so-called multi-component glass such as a _3- Li ₂ O-based crystallized glass can be used. Further, a substrate made of silicon, metal, or the like other than the above glass can be used. Examples of the metal substrate include an invar alloy (Fe—Ni alloy).

  As described above, in the case of the mask blank substrate 10 for EUV exposure, a multi-component glass material is used because the substrate is required to have low thermal expansion characteristics. However, the multi-component glass material has a problem that it is difficult to obtain high smoothness as compared with synthetic quartz glass. In order to solve this problem, a thin film made of a metal or an alloy or a material containing at least one of oxygen, nitrogen and carbon in any of these is formed on a substrate made of a multi-component glass material. Then, by mirror-polishing and surface-treating the surface of such a thin film, a surface having a surface roughness in the above range can be formed relatively easily.

  As a material of the thin film, for example, Ta (tantalum), an alloy containing Ta, or a Ta compound containing at least one of oxygen, nitrogen, and carbon in any of these is preferable. Examples of the Ta compound include, for example, TaB, TaN, TaO, TaON, TaCON, TaBN, TaBO, TaBON, TaBCON, TaHf, TaHfO, TaHfN, TaHfON, TaHfCON, TaSi, TaSiO, TaSiN, and TaSiO. it can. Among these Ta compounds, TaN, TaON, TaCON, TaBN, TaBON, TaBCON, TaHfN, TaHfON, TaHfCON, TaSiN, TaSiON and TaSiCON containing nitrogen (N) are more preferable. The thin film preferably has an amorphous structure from the viewpoint of high smoothness of the thin film surface. The crystal structure of the thin film can be measured by an X-ray diffractometer (XRD).

  In the present invention, the processing method for obtaining the surface roughness specified above is not particularly limited.

[Substrate 20 with multilayer reflective film]
Next, the substrate 20 with a multilayer reflective film that can be used for the reflective mask blank 30 of the present invention will be described below.

  FIG. 2 is a schematic diagram illustrating an example of the substrate 20 with a multilayer reflective film that can be used for the reflective mask blank 30.

  The substrate with a multilayer reflective film 20 of the present embodiment has a structure in which the multilayer reflective film 21 is provided on the main surface of the mask blank substrate 10 on the side on which the transfer pattern is formed. The multilayer reflective film 21 has a function of reflecting EUV light in the reflective mask 40 for EUV lithography, and has a multilayer reflective film 21 structure in which elements having different refractive indexes are periodically laminated. .

  The material of the multilayer reflective film 21 is not particularly limited as long as it reflects EUV light, but the reflectance alone (absolute reflectance) is usually 65% or more, and the upper limit is usually 73%. In general, such a multilayer reflective film 21 is composed of a thin film made of a material having a high refractive index (high refractive index layer) and a thin film made of a material having a low refractive index (low refractive index layer) alternately. The multilayer reflective film 21 can be a laminate of about 60 cycles.

  For example, the multilayer reflective film 21 for EUV light having a wavelength of 13 to 14 nm is preferably a Mo / Si periodic multilayer film in which Mo films and Si films are alternately stacked for about 40 periods. In addition, as the multilayer reflective film 21 used in the EUV light region, a Ru / Si periodic multilayer film, a Mo / Be periodic multilayer film, a Mo compound / Si compound periodic multilayer film, a Si / Nb periodic multilayer film, a Si / Mo / A periodic Ru film, a periodic Si / Mo / Ru / Mo multilayer film, a periodic Si / Ru / Mo / Ru multilayer film, or the like can be used.

  The method of forming the multilayer reflective film 21 is known in the art, and can be formed by forming each layer by, for example, a magnetron sputtering method or an ion beam sputtering method. In the case of the above-described Mo / Si periodic multilayer film, for example, first, an Si film having a thickness of about several nm is formed on the substrate 10 using an Si target by an ion beam sputtering method, and then, using an Mo target. A multi-layer reflective film 21 is formed by forming a Mo film having a thickness of about several nanometers and stacking the Mo film with one cycle for 40 to 60 cycles.

  When manufacturing the reflective mask blank 30 of the present invention, the multilayer reflective film 21 is formed by alternately irradiating a sputtering target of a high-refractive-index material and a sputtering target of a low-refractive-index material with an ion beam and by an ion beam sputtering method. Is preferably performed. By forming the multilayer reflective film 21 by a predetermined ion beam sputtering method, it is possible to obtain the multilayer reflective film 21 having a good reflectance characteristic for EUV light.

  The reflective mask blank 30 of the present invention further includes a protective film 22 in which the mask blank multilayer film 26 is disposed in contact with the surface of the multilayer reflective film 21 opposite to the mask blank substrate 10. Is preferred. That is, in the reflective mask blank 30 of the present invention, it is preferable that the protective film 22 is formed on the multilayer reflective film 21.

  On the multilayer reflective film 21 formed as described above, a protective film 22 (see FIG. 3) for protecting the multilayer reflective film 21 from dry etching and wet cleaning in the manufacturing process of the reflective mask 40 for EUV lithography. ) Can also be formed. As described above, a configuration in which the multilayer reflective film 21 and the protective film 22 are provided on the mask blank substrate 10 can also be the substrate 20 with the multilayer reflective film in the present invention.

  The material of the protective film 22 is, for example, Ru, Ru- (Nb, Zr, Y, B, Ti, La, Mo), Si- (Ru, Rh, Cr, B), Si, Zr, Nb. , La, B, etc., the use of a material containing ruthenium (Ru) improves the reflectance characteristics of the multilayer reflective film 21. Specifically, Ru and Ru- (Nb, Zr, Y, B, Ti, La, Mo) are preferable. Such a protective film 22 is particularly effective when the phase shift film 24 is made of a Ta-based material and the phase shift film 24 is patterned by dry etching of a Cl-based gas.

In the above-mentioned substrate 20 with a multilayer reflective film, a power spectrum of a spatial frequency of 10 to 100 μm ⁻¹ obtained by measuring an area of 1 μm × 1 μm on the surface of the multilayer reflective film 21 or the protective film 22 with an atomic force microscope. density can be 7 nm ⁴ or less, preferably to 6.5 nm ⁴ or less. With such a configuration, the surface of the phase shift film 24 formed thereafter can have a predetermined power spectrum density at a predetermined spatial frequency.

  Further, in order to improve the reflection characteristics necessary for the substrate 20 with a multilayer reflective film, in the substrate 20 with a multilayer reflective film, a region of 1 μm × 1 μm is formed on the surface of the multilayer reflective film 21 or the protective film 22 by an interatomic process. The root-mean-square roughness (Rms) obtained by measurement with a force microscope is desirably 0.15 nm or less, preferably 0.12 nm or less, and more preferably 0.10 nm or less.

  In order for the surface of the multilayer reflective film 21 or the protective film 22 to have the power spectrum density in the above range while maintaining the surface morphology of the substrate 10 in the above range, the multilayer reflective film 21 should be positioned normal to the main surface of the substrate 10. It is obtained by forming a film by a sputtering method so that a high refractive index layer and a low refractive index layer are deposited obliquely. More specifically, the incident angle of sputtered particles for forming a low refractive index layer such as Mo and the incident angle of sputtered particles for forming a high refractive index layer such as Si are more than 0 degrees. It is preferable to form the film at a temperature equal to or lower than the temperature. More preferably, it is more than 0 degree and 40 degrees or less, and further preferably, it is more than 0 degree and 30 degrees or less. Further, the protective film 22 formed on the multilayer reflective film 21 is also ion-exposed so that the protective film 22 is continuously deposited obliquely to the normal of the main surface of the substrate 10 after the multilayer reflective film 21 is formed. It is preferably formed by a beam sputtering method.

  In the substrate 20 with the multilayer reflective film, a back conductive film 23 (see FIG. 3) is formed on the surface of the substrate 10 opposite to the surface in contact with the multilayer reflective film 21 for the purpose of electrostatic chuck. Can be. As described above, the multilayer reflective film 21 and the protective film 22 are provided on the mask blank substrate 10 on the side where the transfer pattern is formed, and the back conductive film 23 is provided on the surface opposite to the surface in contact with the multilayer reflective film 21. May be used as the substrate 20 with a multilayer reflective film according to the present invention. The electrical characteristics (sheet resistance) required for the back conductive film 23 are usually 100Ω / □ or less. The method of forming the back surface conductive film 23 is known. For example, the back surface conductive film 23 can be formed by a magnetron sputtering method or an ion beam sputtering method using a metal or alloy target such as Cr or Ta.

  Further, as the substrate 20 with a multilayer reflective film of the present embodiment, an underlayer may be formed between the substrate 10 and the multilayer reflective film 21. The underlayer can be formed for the purpose of improving the smoothness of the main surface of the substrate 10, for reducing defects, for the purpose of enhancing the reflectivity of the multilayer reflective film 21, and for correcting the stress of the multilayer reflective film 21.

[Reflective mask blank 30]
Next, the reflective mask blank 30 of the present invention will be described.

  FIG. 3 is a schematic diagram illustrating an example of the reflective mask blank 30 of the present invention. The reflective mask blank 30 shown in FIG. 3 has a configuration in which a phase shift film 24 serving as a transfer pattern is formed on the protective film 22 of the above-described substrate 20 with a multilayer reflective film.

[Phase shift film]
The phase shift film 24 is formed on the multilayer reflective film 21 or on the protective film 22 formed on the multilayer reflective film 21. The phase shift film 24 shifts the phase by absorbing EUV light and partially reflecting the EUV light. That is, in the reflection type mask 40 in which the phase shift film 24 is patterned, in a portion where the phase shift film 24 remains, a part is reflected so that the EUV light is absorbed and the pattern transfer is not affected so that the multilayer reflection is performed. This is to form a phase difference with the light reflected from the film 21. The phase shift film 24 is formed such that the absolute reflectance for EUV light is 1 to 6%, and the phase difference between the reflected light from the phase shift film 24 and the reflected light from the multilayer reflective film 21 is 170 to 190 degrees. You. The thickness of the phase shift film 24 is appropriately determined according to the material to be used and the design value of the absolute reflectance, and so that the phase difference falls within the above range.

  The material of the phase shift film 24 is not particularly limited as long as it has a function of absorbing EUV light and can be removed by etching or the like. In the present embodiment, from the viewpoint of etching selectivity and the like, tantalum alone or a tantalum-based material containing tantalum is used. Specifically, the tantalum-based material is a TaB alloy containing Ta and B, a TaSi alloy containing Ta and Si, a Ta alloy containing Ta and other transition metals (for example, Pt, Pd, Ag), or a Ta alloy. A tantalum-based compound obtained by adding N, O, H, C, or the like to a metal or an alloy thereof may be used.

  Such a phase shift film 24 made of tantalum or a tantalum compound can be formed by a known method such as a DC sputtering method or an RF sputtering method.

  The crystal state of the phase shift film 24 is preferably an amorphous or microcrystalline structure from the viewpoint of smoothness. If the phase shift film 24 is not smooth, the edge roughness of the phase shift film pattern increases, and the dimensional accuracy of the pattern may deteriorate. A preferable surface roughness of the phase shift film 24 is a root mean square roughness (Rms) of 0.50 nm or less, more preferably Rms of 0.45 nm or less, still more preferably Rms of 0.40 nm or less, and still more preferably. Rms is 0.36 nm.

  Ta is a phase shift film material excellent in processability because it has a large EUV light absorption coefficient and can be easily dry-etched with a chlorine-based gas or a fluorine-based gas. Further, by adding B and / or Si, Ge or the like to Ta, an amorphous material can be easily obtained, and the smoothness of the phase shift film 24 can be improved. Further, if N and / or O is added to Ta, the resistance of the phase shift film 24 to oxidation is improved, so that the effect of improving the stability over time can be obtained.

  The phase shift film 24 is not limited to a single layer of a tantalum-based material layer, and may be formed by stacking a plurality of tantalum-based material layers. The phase shift film 24 includes a film formed by laminating a tantalum-based material layer and another material layer. Specifically, a chromium-based material layer and a ruthenium-based material layer can be used as other material layers. In this case, as a chromium-based material, Cr alone, Cr alloy containing Cr and other transition metals (for example, Pt, Pd, Ag), and N, O, H, C, etc. are added to the Cr metal and / or Cr alloy. Chromium-based compounds can be used. The ruthenium-based material may be a simple Ru metal or a Ru alloy containing Ru and a metal such as Nb, Zr, Y, B, Ti, La, Mo, Co and / or Re. Further, a ruthenium-based compound obtained by adding N, O, H, and / or C to Ru metal or an alloy thereof may be used. When the phase shift film 24 is formed by a laminated structure of a tantalum-based material layer and another material layer (when another material layer is laminated on the tantalum-based material layer), the film formation is started to be completed. It is preferable to form the film continuously without exposing it to the atmosphere. By doing so, it is possible to prevent an oxide layer (tantalum oxide layer) from being formed on the surface of the tantalum-based material layer (a step for removing the tantalum oxide layer is not required).

  The lamination order and the number of laminations of the tantalum-based material layer and the chromium-based material layer in the phase shift film 24 are not particularly limited, and for example, a Ta / Cr two-layer structure, a Cr / Ta two-layer structure, a Ta / Cr / Ta three-layer structure, Cr / Ta / Cr three-layer structure, Ta / Cr / Ta / Cr four-layer structure, Cr / Ta / Cr / Ta four-layer structure, Ta / Ta / Cr / Cr It may have a four-layer structure, a four-layer structure of Cr / Cr / Ta / Ta, or the like, or may have other structures. However, the material adjacent to the multilayer reflective film 21 or the protective film 22 formed on the multilayer reflective film 21 is more preferably a tantalum-based material layer. The outermost layer of the phase shift film 24 can be a chromium-based material layer or a tantalum-based material layer (for example, a TaSi-based material layer). However, the outermost surface layer of the phase shift film 24 is more preferably a chromium-based material layer. This is because the chromium-based material layer can also have a function as an antioxidant film for the tantalum-based material layer. (Ta is the uppermost layer, so that oxidation of the chromium-based material layer and a decrease in the etching rate are suppressed.) . Further, when a chromium-based material layer is used as the outermost surface layer of the phase shift film 24, from the viewpoint of controlling the power spectrum density of the surface of the phase shift film 24, a material containing nitrogen, specifically, CrN, CrON, It is preferable to use CrCN, CrCON, CrHN, CrOHN, CrCHN, and CrCONH. Further, from the viewpoint of chemical resistance during mask cleaning, a material containing carbon, specifically, CrC, CrCO, CrCN, CrCON, CrCH, CrCOH, CrCHN, and CrCONH is more preferable. Ta and Cr include nitrides, oxides, and alloys in addition to single metals, and do not necessarily have to have the same material and composition.

  The lamination order and the number of laminations of the tantalum-based material layer and the ruthenium-based material layer in the phase shift film 24 are not particularly limited. For example, a Ta / Ru two-layer structure or a Ta / Ru / Ta three-layer structure from the substrate 10 side. , A four-layer structure of Ta / Ru / Ta / Ru, a four-layer structure of Ta / Ta / Ru / Ru, or the like, or other layers. Therefore, the outermost layer of the phase shift film 24 can be a ruthenium-based material layer or a tantalum-based material layer (for example, a TaSi-based material layer). However, the material adjacent to the multilayer reflective film 21 or the protective film 22 formed on the multilayer reflective film 21 is more preferably a tantalum-based material layer, and the outermost surface layer of the phase shift film 24 is a ruthenium-based material. More preferably, it is a layer. This allows the ruthenium-based material layer to also have a function as an antioxidant film for the tantalum-based material layer. Ta and Ru include nitrides, oxides, and alloys in addition to single metals, and do not necessarily have to have the same material and composition.

  Further, in the phase shift film 24, a tantalum-based material layer, a ruthenium-based material layer, and a chromium-based material layer may be laminated, and the lamination order and the number of laminations are not particularly limited. For example, a three-layer structure of Ta / Ru / Cr, a three-layer structure of Ta / Cr / Ru, or the like may be used from the substrate 10 side, or other than these.

  The phase shift film 24 of the reflective mask blank 30 of the present invention preferably has a tantalum-based material layer containing tantalum and nitrogen, and a chromium-based material layer containing chromium and nitrogen on the tantalum-based material layer. Since the phase shift film 24 includes the tantalum-based material layer and the chromium-based material layer, it is possible to obtain a phase shift film having a predetermined phase shift effect and a high absolute reflectance for EUV light.

  Note that the chromium-based material layer preferably has a thickness of 5 nm to 30 nm. By setting the thickness of the chromium-based material layer covering the tantalum-based material layer to a predetermined range, formation of an oxide layer (tantalum oxide layer) on the surface of the tantalum-based material layer can be prevented.

  In the reflective mask blank 30 of the present invention, when the phase shift film 24 includes a tantalum-based material layer containing tantalum and nitrogen, the nitrogen content is preferably 5 atomic% or more and 50 atomic% or less, More preferably, it is 5 atomic% or more and 30 atomic% or less, and further preferably, 5 atomic% or more and 20 atomic% or less. When the phase shift film 24 includes a chromium-based material layer containing chromium and nitrogen, the nitrogen content is preferably 5 atomic% or more and 50 atomic% or less, and more preferably 5 atomic% or more and 30 atomic% or less. Atomic% or less, more preferably 5 to 20 atomic%.

When the phase shift film 24 includes a tantalum-based material layer containing tantalum and nitrogen, the content of nitrogen is not less than 5 atomic% and not more than 50 atomic%, and the phase shift film 24 is made of chromium and nitrogen. When the chromium-based material layer containing chromium is contained, the content of nitrogen is not less than 5 atomic% and not more than 50 atomic%, so that the root mean square roughness (Rms) of the surface of the phase shift film 24 and 1 μm × 1 μm Since the power spectrum density, which is the amplitude intensity of all of the roughness components of the spatial frequency of 10 to 100 μm ⁻¹ that can be detected in the region, falls within a predetermined value range, furthermore, the expansion of the crystal grains constituting the phase shift film can be suppressed. In addition, the pattern edge roughness when the phase shift film is patterned can be reduced.

In the case of the reflective mask blank 30 of the present invention, in a 1 μm × 1 μm region on the surface of the phase shift film 24, the root mean square roughness (Rms) obtained by measurement with an atomic force microscope, and a spatial frequency of 10 to 100 μm The power spectral density of ^-1 is set to a value within a predetermined range. By using the reflective mask blank 30 of the present invention having such a structure, when the phase shift film 24 is designed so that the absolute reflectance with respect to EUV light falls within a predetermined range, the difference (deviation) from the design value is obtained. ) Can be reduced to obtain the phase shift film 24 having a high absolute reflectance in a predetermined range. Therefore, by using the reflective mask blank 30 of the present invention, it is possible to manufacture the reflective mask 40 capable of obtaining high contrast at the edge of the phase shift film pattern 27.

  In addition, the reflective mask blank 30 of the present invention is not limited to the configuration shown in FIG. For example, a resist film serving as a mask for patterning the phase shift film 24 can be formed on the phase shift film 24, and the reflective mask blank 30 with the resist film can be used as the reflective mask blank 30 of the present invention. It can be. The resist film formed on the phase shift film 24 may be either a positive type or a negative type. Further, it may be for electron beam drawing or laser drawing. Further, a so-called hard mask film (etching mask film) can be formed between the phase shift film 24 and the resist film, and this embodiment can also serve as the reflective mask blank 30 of the present invention.

[Etching mask film 25]
The reflective mask blank 30 of the present invention further includes an etching mask film 25 in which the mask blank multilayer film 26 is disposed in contact with the surface of the phase shift film 24 opposite to the mask blank substrate 10. It is preferred to include. In the case of the reflective mask blank 30 shown in FIG. 5, the mask blank multilayer film 26 on the main surface of the mask blank substrate 10 includes the multilayer reflective film 21, the protective film 22, and the phase shift film 24, Further, an etching mask film 25 is provided. The reflective mask blank 30 of the present invention can further have a resist film on the outermost surface of the mask blank multilayer film 26 of the reflective mask blank 30 shown in FIG.

  Specifically, in the reflective mask blank 30 of the present invention, when the uppermost material of the phase shift film is made of a chromium-based material layer containing chromium, the etching mask film 25 made of a material containing tantalum is formed. Preferably, it has a structure. In the case where the material of the uppermost layer of the phase shift film 24 is Ta alone or a material containing Ta as a main component, a structure in which an etching mask film 25 made of a material containing chromium is formed on the phase shift film 24. It is preferable that By forming the reflective mask blank 30 having such a structure, after forming a transfer pattern on the phase shift film 24, the etching mask film 25 is formed of a chlorine-based gas, a fluorine-based gas, or a mixed gas of a chlorine-based gas and an oxygen gas. Even if the phase shift film pattern 27 is peeled off by dry etching using a mask, the reflection type mask 40 having good optical characteristics of the phase shift film pattern 27 can be manufactured. Further, it is possible to manufacture the reflection type mask 40 in which the line edge roughness of the transfer pattern formed on the phase shift film 24 is good.

  Examples of the material containing tantalum that forms the etching mask film 25 include TaN, TaON, TaCON, TaBN, TaBON, TaBCON, TaHfN, TaHfON, TaHfCON, TaSiN, TaSiON, TaSiCON, and the like. Examples of the material containing chromium that forms the etching mask film 25 include a material containing chromium and one or more elements selected from nitrogen, oxygen, carbon, and boron. For example, CrN, CrON, CrCN, CrCON, CrBN, CrBON, CrBCN, CrBOCN and the like can be mentioned. The material may contain a metal other than chromium as long as the effects of the present invention can be obtained. The thickness of the etching mask film 25 is preferably 3 nm or more from the viewpoint of obtaining a function as an etching mask for accurately forming a transfer pattern on the phase shift film 24. The thickness of the etching mask film 25 is desirably 15 nm or less from the viewpoint of reducing the thickness of the resist film.

When the outermost surface of the reflective mask blank 30 of the present invention is the etching mask film 25, as in the case where the outermost surface of the reflective mask blank 30 is the phase shift film 24, the 1 μm × 1 μm surface of the etching mask film 25 is formed. In the region, the root-mean-square roughness (Rms) obtained by measurement with an atomic force microscope and the power spectrum density at a spatial frequency of 10 to 100 μm ⁻¹ are set to values within a predetermined range so that the phase shift is achieved. The power spectral density of the film can also be managed. By using the reflective mask blank 30 of the present invention having such a structure, when the phase shift film 24 is designed so that the absolute reflectance with respect to EUV light falls within a predetermined range, the difference (deviation) from the design value is obtained. ) Can be reduced to obtain the phase shift film 24 having an absolute reflectance in a high predetermined range, so that the reflection type mask 40 capable of obtaining a high contrast at the edge portion of the phase shift film pattern 27 is manufactured. Can be.

[Method of Manufacturing Reflective Mask Blank 30]
Next, a method for manufacturing the reflective mask blank 30 of the present invention will be described.

The reflective mask blank 30 of the present invention includes a multilayer reflective film 21 and a phase shift film 24 in which high refractive index layers and low refractive index layers are alternately laminated on the main surface of the mask blank substrate 10. In the method of manufacturing the reflective mask blank 30 according to the present invention, a step of forming a multilayer reflective film 21 on the main surface of the mask blank substrate 10 and a step of forming a phase shift film 24 on the multilayer reflective film 21. And a step. In the manufacturing method of the reflective mask blank 30 of the present invention, the root mean square roughness (Rms) obtained by measuring with an atomic force microscope in a 1 μm × 1 μm region of the surface of the reflective mask blank 30 is 0. The phase shift film 24 is formed so as to have a power spectrum density of 50 nm or less and a power spectrum density of 17 nm ⁴ or less at a spatial frequency of 10 to 100 μm ⁻¹ .

On the surface of the phase shift film 24 of the reflective mask blank 30 of the present invention, Rms is set to 0.50 nm or less (preferably 0.45 nm or less, more preferably 0.40 nm or less, and still more preferably 0.36 nm or less). The power spectrum density, which is the amplitude intensity of all the roughness components having a spatial frequency of 10 to 100 μm ⁻¹ that can be detected in an area of 1 μm × 1 μm, is reduced to 17 nm ⁴ or less (preferably 14 nm ⁴ or less, more preferably 10 nm ⁴ or less). By doing so, when the phase shift film 24 is designed so that the absolute reflectance with respect to EUV light is within a predetermined range, the difference (deviation) from the design value is reduced and the absolute reflectance is within a high predetermined range. Since the phase shift film 24 can be obtained, a high contrast can be obtained at the edge of the phase shift film pattern 27. It is possible to manufacture a mold mask 40.

In the method of manufacturing the reflective mask blank 30 of the present invention, in the step of forming the phase shift film 24, the phase shift film 24 is formed by a reactive sputtering method using a sputtering target made of a material included in the phase shift film 24. It is preferable that the phase shift film 24 is formed so as to contain components contained in the atmosphere gas during the reactive sputtering. By adjusting the flow rate of the atmosphere gas during the film formation by the reactive sputtering method, the root-mean-square roughness (Rms) of the surface of the phase shift film 24 and the spatial frequency 10 that can be detected in the region of 1 μm × 1 μm are obtained. It can be adjusted so that the power spectrum density, which is the amplitude intensity of all the roughness components of １００100 μm ⁻¹ , falls within a predetermined value range.

  When the phase shift film 24 is formed by the reactive sputtering method, the atmosphere gas is preferably a mixed gas containing an inert gas and a nitrogen gas. In this case, since the flow rate of nitrogen can be adjusted, the phase shift film 24 having an appropriate composition can be obtained. As a result, on the surface of the phase shift film 24, the phase shift film 24 having appropriate root mean square roughness (Rms) and power spectrum density can be reliably obtained. For example, when the phase shift film 24 is composed of a TaN layer and a CrOCN layer, an appropriate root-mean-square control is performed by adjusting the flow rate of nitrogen during the film formation in both the TaN layer formation and the CrOCN layer formation. The phase shift film 24 having the square root roughness (Rms) and the power spectrum density can be reliably obtained.

  In the method of manufacturing the reflective mask blank 30 of the present invention, the phase shift film 24 is preferably formed using a sputtering target of a material containing tantalum. As a result, it is possible to form the phase shift film 24 having appropriate absorption including tantalum.

  The method of manufacturing the reflective mask blank 30 of the present invention preferably further includes a step of forming a protective film 22 disposed in contact with the surface of the multilayer reflective film 21. By forming the protective film 22, damage to the surface of the multilayer reflective film 21 at the time of manufacturing a transfer mask (EUV mask) can be suppressed, so that the reflectance characteristics with respect to EUV light are further improved.

  The protective film 22 is preferably formed by an ion beam sputtering method in which an ion beam is irradiated on a sputtering target made of the material of the protective film 22. Since the surface of the protective film is smoothed by the ion beam sputtering method, the surface of the phase shift film formed on the protective film or the surface of the etching mask film further formed on the phase shift film can be smoothed. .

  The method of manufacturing the reflective mask blank 30 of the present invention preferably further includes a step of forming an etching mask film 25 disposed in contact with the surface of the phase shift film 24. By forming the etching mask film 25 having a dry etching characteristic different from that of the phase shift film 24, a high-accuracy transfer pattern can be formed when a transfer pattern is formed on the phase shift film 24.

[Reflective mask 40]
Next, the reflective mask 40 according to one embodiment of the present invention will be described below.

  FIG. 4 is a schematic diagram illustrating the reflective mask 40 of the present embodiment. The reflective mask 40 of the present invention has a configuration in which the phase shift film 24 in the reflective mask blank 30 is patterned to form a phase shift film pattern 27 on the multilayer reflective film 21 or the protective film 22. . When the reflective mask 40 of the present embodiment is exposed to exposure light such as EUV light, the exposure light is absorbed in a portion of the mask surface where the phase shift film 24 is present, and is exposed in other portions where the phase shift film 24 is removed. The exposure light is reflected by the protective film 22 and the multilayer reflective film 21 thus used, so that it can be used as a reflective mask 40 for lithography. When the reflection type mask 40 of the present invention is designed so that the absolute reflectance of the phase shift film 24 with respect to EUV light is in a predetermined high range, the difference (deviation) from the design value is reduced to achieve a high predetermined range. Since the phase shift film 24 having the absolute reflectance can be obtained, a high contrast can be obtained at the edge portion of the phase shift film pattern 27.

Patterning of the phase shift film 24 can be performed as follows. That is, first, a resist film pattern is formed on the surface of the phase shift film 24. By performing dry etching with an etching gas using the resist film pattern as a mask, the phase shift film 24 is etched, and a phase shift film pattern is formed. At this time, as an etching gas, a chlorine-based gas such as Cl ₂ , SiCl ₄ , CHCl ₃ , CCl ₄ , a mixed gas containing these chlorine-based gas and O ₂ at a predetermined ratio, a chlorine-based gas and He are specified. , A mixed gas containing a chlorine-based gas and Ar at a predetermined ratio, CF ₄ , CHF ₃ , C ₂ F ₆ , C ₃ F ₆ , C ₄ F ₆ , C ₄ F ₈ , CH ₂ F ₂ , CH ₃ F, C ₃ F ₈ , SF ₆ , F, and other fluorine-based gases, a mixed gas containing these fluorine-based gases and O ₂ at a predetermined ratio, and O ₂ gas. When the phase shift film 24 has a laminated structure of a plurality of materials, etching using an etching gas suitable for each material can be performed a plurality of times.

  Next, for example, after the resist film pattern is removed with a resist stripping solution, wet cleaning using an acidic or alkaline aqueous solution is performed to obtain the reflective mask 40 for EUV lithography achieving high reflectance. Note that, depending on the configuration of the phase shift film 24, the resist film can be removed at the same time as etching one layer of the layered structure of the phase shift film 24. In this case, a step only for removing the resist film pattern becomes unnecessary. When the etching mask film 25 is provided, a step of removing the etching mask film 25 may be required separately.

  In addition, since the reflective mask blank 30 has the protective film 22 on the multilayer reflective film 21, damage to the surface of the multilayer reflective film 21 when manufacturing the reflective mask 40 (EUV mask) can be suppressed. Therefore, it is preferable that the reflective mask 40 also has the protective film 22 on the multilayer reflective film 21. As a result, the reflectance characteristics of the reflective mask 40 for EUV light are improved.

The reflection type mask 40 of the present invention has a root-mean-square roughness (Rms) of 0.15 nm or less measured by an atomic force microscope in a 1 μm × 1 μm region on the surface of the multilayer reflective film 21 or the protective film 22. Preferably, the power spectrum density at a spatial frequency of 10 to 100 μm ⁻¹ is 7 nm ⁴ or less. By setting a predetermined root mean square roughness (Rms) and a power spectrum density of a predetermined spatial frequency in a predetermined range in a predetermined region on the surface of the multilayer reflective film 21 or the protective film 22 of the reflective mask 40, EUV light is prevented. Since a phase shift film having a higher absolute reflectance can be obtained, the intensity of exposure light at the time of exposure for manufacturing a semiconductor device can be increased. Therefore, the throughput at the time of manufacturing the semiconductor device can be improved.

The reflective mask 40 of the present invention, the power spectral density of the phase shift film pattern 27 surface, the difference between the power spectral density in the multilayer reflective film 21 or the protective layer 22 surface is preferably 10 nm ⁴ or less. When the difference between the predetermined power spectrum densities is within the predetermined range, it is possible to more reliably obtain the reflective mask 40 that can obtain high contrast at the edge of the phase shift film pattern 27.

[Method of Manufacturing Semiconductor Device]
A resist pattern formed on an object to be transferred such as a semiconductor substrate by a lithography process using the reflective mask 40 described above and an exposure apparatus is used to form a circuit pattern such as a circuit pattern based on the phase shift film pattern 27 of the reflective mask 40. By transferring the transfer pattern and passing through various other steps, a semiconductor device in which various transfer patterns and the like are formed on a transfer target such as a semiconductor substrate can be manufactured.

  According to the method of manufacturing a semiconductor device of the present invention, the reflection type mask 40 capable of obtaining a high contrast at the edge of the phase shift film pattern can be used, so that the resist film formed on the transfer target such as a semiconductor substrate can be used. It is possible to manufacture a semiconductor device having a fine and high-accuracy transfer pattern in which the size of a transfer pattern such as a circuit pattern to be transferred is accurate.

  Next, an example of manufacturing the reflective mask blank 30 and the reflective mask 40 according to the present embodiment will be described as an example.

  First, a multilayer reflective film 21 and a phase shift film 24 are formed on the surface of the mask blank substrate 10 for EUV exposure as described below, and a back conductive film 23 is formed on the back surface of the mask blank substrate 10. Thus, the reflective mask blanks 30 of Examples 1 to 3 and Comparative Example 1 were manufactured. Accordingly, the reflective mask blanks 30 of Examples 1 to 3 and Comparative Example 1 have a structure of the back conductive film 23 / mask blank substrate 10 / multilayer reflective film 21 / protective film 22 / phase shift film 24.

<Preparation of Mask Blank Substrate 10>
As a mask blank substrate 10, a SiO ₂ —TiO ₂ glass substrate 10 having a size of 152 mm × 152 mm and a thickness of 6.35 mm is prepared, and the front and back surfaces of the glass substrate 10 are cleaned using a double-side polishing apparatus. After polishing step by step with cerium oxide abrasive grains or colloidal silica abrasive grains, surface treatment was carried out with low-concentration hydrofluoric acid. The surface roughness of the surface of the obtained glass substrate 10 was measured with an atomic force microscope, and the root mean square roughness (Rms) was 0.5 nm.

  The surface shape (surface shape, flatness) and TTV (plate thickness variation) of a 148 mm × 148 mm region on the front and back surfaces of the glass substrate 10 were measured with a wavelength shift interferometer using a wavelength modulation laser. As a result, the flatness of the front and back surfaces of the glass substrate 10 was 290 nm (convex shape). The measurement result of the surface shape (flatness) of the surface of the glass substrate 10 is stored in a computer as height information with respect to a reference plane at each measurement point, and the reference value of the surface flatness required for the glass substrate 10 is 50 nm (convex). Shape) and the back surface flatness reference value 50 nm, and the difference (required removal amount) was calculated by a computer.

  Next, processing conditions for local surface processing according to the required removal amount were set in the surface of the glass substrate 10 for each processing spot shape region. Using a dummy substrate in advance, a dummy substrate is processed in a spot for a certain period of time without moving the substrate in the same manner as in actual processing, and the shape is measured using the same measuring device as the above-described apparatus for measuring the front and rear surface shapes. , And the processing volume of the spot per unit time is calculated. Then, according to the required removal amount obtained from the information on the spot and the information on the surface shape of the glass substrate 10, the scanning speed at the time of raster scanning the glass substrate 10 was determined.

  According to the set processing conditions, the flatness of the front and back surfaces of the glass substrate 10 is set to be equal to or less than the above-described reference value by a magnetic viscoelastic fluid polishing (MRF) processing method using a substrate finishing apparatus using a magnetic fluid. The surface shape was adjusted by local surface processing. The magnetic viscoelastic fluid used at this time contained an iron component, and the polishing slurry used was an alkaline aqueous solution containing about 2% by weight of cerium oxide as a polishing agent. Thereafter, the glass substrate 10 was immersed in a cleaning tank containing a hydrochloric acid aqueous solution having a concentration of about 10% (temperature of about 25 ° C.) for about 10 minutes, and then rinsed with pure water and dried with isopropyl alcohol (IPA).

  Note that the local processing method of the mask blank substrate 10 in the present invention is not limited to the above-described magnetic viscoelastic fluid polishing method. A processing method using gas cluster ion beams (GCIB) or local plasma may be used.

After that, as a final polishing of the local surface processing, after performing double-sided touch polishing using colloidal silica abrasive grains for the purpose of improving the surface roughness, the surface processing is performed by a catalyst-referred etching method (CARE: Catalyst Referred Etching). Was. This CARE was performed under the following processing conditions.
Processing liquid: pure water Catalyst: platinum Substrate rotation speed: 10.3 rotations / minute Catalyst base plate rotation speed: 10 rotations / minute Processing time: 50 minutes Processing pressure: 250 hPa

  Then, after scrub-cleaning the end surface of the glass substrate 10, the substrate was immersed in a cleaning tank containing aqua regia (temperature of about 65 ° C.) for about 10 minutes, and then rinsed with pure water and dried. The washing with aqua regia was performed a plurality of times until there was no residual platinum as a catalyst on the front and back surfaces of the glass substrate 10.

  On the main surface of the mask blank substrate 10 for EUV exposure obtained as described above, an arbitrary 1 μm × 1 μm region of the transfer pattern formation region (132 mm × 132 mm) was measured with an atomic force microscope. , Root mean square roughness (Rms) was 0.040 nm, and maximum height (Rmax) was 0.40 nm.

The main area of 1 [mu] m × 1 [mu] m at the surface, the spatial frequency 1 [mu] m ^-1 or 10 [mu] m ^-1 or less of the power obtained by measuring an atomic force microscope of the mask blank substrate 10 for EUV exposure obtained as described above The spectral density had a maximum value of 5.29 nm ⁴ and a minimum value of 1.15 nm. The power spectrum density at a spatial frequency of 10 μm ^{−1 to} 100 μm ⁻¹ was a maximum value of 1.18 nm ⁴ and a minimum value of 0.20 nm ⁴ .

<Production of Examples 1 to 3 and Comparative Example 1>
Using an Mo target and a Si target, an Mo layer (low refractive index layer, thickness of 2.8 nm) and a Si layer (high refractive index layer, thickness of 4.2 nm) are alternately laminated by ion beam sputtering (40 pairs of lamination numbers). 4) Finally, a Si layer was formed to a thickness of 4.0 nm, and a multilayer reflective film 21 was formed on the glass substrate 10 described above. When forming the multilayer reflective film 21 by the ion beam sputtering method, the incident angle of the Mo and Si sputtered particles with respect to the normal to the main surface of the glass substrate 10 in the ion beam sputtering was 30 degrees, and the gas flow rate of the ion source was 8 sccm. .

  After the multilayer reflective film 21 was formed, a Ru protective film 22 (thickness: 2.5 nm) was continuously formed on the multilayer reflective film 21 by ion beam sputtering to obtain a substrate 20 with a multilayer reflective film. When forming the Ru protective film 22 by the ion beam sputtering method, the incident angle of the Ru sputtered particles with respect to the normal to the main surface of the substrate was 40 degrees, and the gas flow rate of the ion source was 8 sccm.

  Next, a phase shift film 24 was formed on the main surface of the mask blank substrate 10 by DC magnetron sputtering. In the case of Examples 1 to 3 and Comparative Example 1, as shown in Table 1, a laminated film including two layers of a TaN layer and a CrOCN layer was used as the phase shift film 24.

As the phase shift films 24 of Examples 1 to 3 and Comparative Example 1, a TaN layer (a tantalum-based material layer) and a CrCON layer (a chromium-based material layer) were stacked by DC sputtering to form the phase shift film 24. After the film formation, the element compositions of the TaN layer and the CrCON layer were measured by X-ray photoelectron spectroscopy (XPS method). The TaN layer is a tantalum target, and a TaN layer having a predetermined thickness shown in Table 1 (Ta: 92.5 at%, N: 7.7) by a reactive sputtering method in a mixed gas atmosphere of Ar gas and N ₂ gas. 5 at%). The CrCON layer was a chromium target, and was subjected to reactive sputtering in a mixed gas atmosphere of Ar gas, CO ₂ gas, and N ₂ gas to form a CrCON layer (Cr: 45 at%, C: 10 at%, O: 35 at%, and N: 10 at%) (continuous film formation from the TaN film to the CrCON film without exposure to the air). In addition, the film forming pressure at the time of forming the TaN film in Examples 1 to 3 was set to 0.08 Pa. Further, the film forming pressure at the time of forming the TaN film of Comparative Example 1 was higher than that of Examples 1 to 3, and was 0.12 Pa. Further, the deposition pressure of the CrOCN films of Examples 1 to 3 and Comparative Example 1 was set to 0.12 Pa.

The refractive index n and the extinction coefficient k at a wavelength of 13.5 nm of the TaN layer and the CrCON layer constituting the phase shift film 24 formed as described above were respectively as follows.
TaN layer: n = 0.94, k = 0.034
CrCON layer: n = 0.93, k = 0.037
The thicknesses of the TaN layer and the CrCON layer are set so that the absolute reflectance of the phase shift film 24 is 2.4 to 2.8% and the phase difference is 180 degrees at a wavelength of 13.5 nm. .

  Next, the reflective mask blank 30 of Examples 1 to 3 and Comparative Example 1 was manufactured by forming the back conductive film 23 on the back surface of the mask blank substrate 10.

The back conductive film 23 was formed as follows. That is, the back conductive film 23 was formed by the DC magnetron sputtering method on the back surface of the substrate 20 with the multilayer reflective film used in Examples 1 to 3 and Comparative Example 1 where the multilayer reflective film 21 was not formed. The back conductive film 23 was subjected to reactive sputtering in an atmosphere of a mixed gas of Ar and N ₂ (Ar: N ₂ = 90%: 10%) with a Cr target facing the back surface of the substrate 20 having a multilayer reflective film. . The element composition of the back conductive film 23 was measured by Rutherford backscattering analysis, and was found to be 90 atomic% for Cr and 10 atomic% for N. The thickness of the back conductive film 23 was 20 nm. As described above, the reflective mask blanks 30 of Examples 1 to 3 and Comparative Example 1 were manufactured.

With respect to the surface of the phase shift film 24 of the mask blank substrate 10 for EUV exposure obtained as Examples 1 to 3 and Comparative Example 1, any part of the transfer pattern formation region (132 mm × 132 mm) (specifically, An area of 1 μm × 1 μm (the center of the transfer pattern formation area) was measured with an atomic force microscope. Table 1 shows the surface roughness (root-mean-square roughness, Rms) obtained by measurement with an atomic force microscope, and the power spectrum density at a spatial frequency of 10 to 100 μm ⁻¹ obtained by power spectrum analysis of the surface roughness ( PSD) indicates the maximum value and the integrated value.

FIG. 6 shows the results of power spectrum analysis of Example 3 and Comparative Example 1 for reference. As shown in FIG. 6, the power spectrum density at a spatial frequency of 10 to 100 μm ⁻¹ obtained by measuring an area of 1 μm × 1 μm on the surface of the phase shift film 24 of Example 3 with an atomic force microscope has a maximum value of 15 μm. It was 0.56 nm ⁴ and the minimum value was 0.69 nm ⁴ . On the other hand, as shown in FIG. 6, the power spectrum density at a spatial frequency of 10 to 100 μm ⁻¹ obtained by measuring an area of 1 μm × 1 μm on the surface of the phase shift film 24 of Comparative Example 1 with an atomic force microscope is the maximum. The value was 21.63 nm ⁴ , and the minimum value was 1.52 nm ⁴ .

  As shown in Table 1, in a region of 1 μm × 1 μm on the surface of the phase shift film 24 in Examples 1 to 3, the root mean square roughness (Rms) obtained by measurement with an atomic force microscope is 0.50 nm or less. Met. On the other hand, in a 1 μm × 1 μm region on the surface of the phase shift film 24 of Comparative Example 1, the root mean square roughness (Rms) obtained by measurement with an atomic force microscope was 0.447 nm.

As shown in Table 1, the maximum value of the power spectrum density at a spatial frequency of 10 to 100 μm ^{−1 on} the surface of the phase shift film 24 in Examples 1 to 3 was 17 nm ⁴ or less. On the other hand, the maximum value of the power spectrum density at a spatial frequency of 10 to 100 μm ^{−1 on} the surface of the phase shift film 24 of Comparative Example 1 was larger than 17 nm ^{4 and} was 21.63 nm ⁴ .

Table 1 shows (A) the power spectrum density (PSD) of the surface of the phase shift film and (B) the power of the surface of the multilayer reflective film (with a protective film) after the production of the reflective masks of Examples 1 to 3 and Comparative Example 1. The spectral density (PSD) and the difference (A-B) between (A) and (B) are shown. The difference (A-B) between (A) and (B) in Examples 1 to 3 was 10 nm ⁴ or less. Difference in Comparative Example 1 (A) and (B) contrast (A-B) is 15.17Nm ^4, it was greater than 10 nm ^4.

Further, the root-mean-square roughness Rms of the surfaces of the multilayer reflective films (with a protective film) of Examples 1 to 3 and Comparative Example 1 was 0.138 nm, which was 0.15 nm or less. PSD maximum value of the spatial frequency 10 to 100 [mu] m ^-1 in Examples 1 to 3 and the multilayer reflective film of Comparative Example 1 (protective with film) surface was 6.46nm ^4, it was 7 nm ⁴ or less.

Table 1 shows design values and measured values of the absolute reflectance _RPSM of the phase shift films 24 of Examples 1 to 3 and Comparative Example 1, and the difference (deviation) between the designed value and the measured value. The absolute reflectance _RPSM of the phase shift film 24 was measured using an EUV reflectance measurement (LPR-1016) device. At this time, EUV light having a wavelength of 13.5 nm was used as measurement light for measuring the absolute reflectance. Note that the absolute reflectance R _ML of the multilayer reflective film surface was 65%. Table 1 As is apparent from the absolute reflectance _{R PSM} is as high as 2.0% or more, the difference between the design value and the measured value of absolute reflectance _{R PSM} (shift of the phase shift film 24 of Examples 1 to 3 ) Was as small as 1.0% or less (0 to -0.8%). The absolute reflectance _{R PSM} phase shift film 24 of Comparative Example 1 In contrast, small as 1.7% or more, the difference between the design value and the measured value of absolute reflectance _{R PSM} (deviation) is -1.1 % Was relatively large. Therefore, it was clarified that the mask blanks of Examples 1 to 3 had a high absolute reflectance to EUV light and a small deviation from the measured value.

<Preparation of the reflective mask 40>
A resist was applied to the surfaces of the phase shift films 24 of the reflective mask blanks 30 of Examples 1 to 3 and Comparative Example 1 by a spin coating method, and a 150-nm-thick resist film was formed through a heating and cooling process. . Next, a resist pattern was formed through a desired pattern drawing and developing process. Using the resist pattern as a mask, the phase shift film 24 was patterned by predetermined dry etching to form a phase shift film pattern 27 on the protective film 22. The phase shift film 24 is a laminated film composed of two layers of TaN layer and CrOCN layer, mixing of chlorine (Cl _2), and mixed gas of oxygen _{(O 2)} (chlorine (Cl ₂₎ and oxygen _{(O 2)} Dry etching can be performed at a ratio (flow ratio) of 4: 1).

  Thereafter, the resist film was removed, and the same chemical cleaning was performed as described above, to thereby produce the reflective masks 40 of Examples 1 to 3 and Comparative Example 1.

<Semiconductor device manufacturing method>
Using the reflection type masks 40 of Examples 1 to 3 and Comparative Example 1, using an exposure apparatus, pattern transfer is performed on a resist film on a semiconductor substrate, which is a transfer target. Then, when a semiconductor device is manufactured, a high contrast is obtained at the edge portion of the phase shift film pattern of the reflection type mask, so that a semiconductor device with accurate dimensions of a transfer pattern can be manufactured.

  In the manufacture of the substrate 20 with a multilayer reflective film and the reflective mask blank 30, the multilayer reflective film 21 and the protective film 22 were formed on the main surface of the mask blank substrate 10 on the side where the transfer pattern was formed. Thereafter, the back conductive film 23 is formed on the back surface opposite to the main surface, but is not limited to this. After the back conductive film 23 is formed on the main surface of the mask blank substrate 10 opposite to the main surface on which the transfer pattern is formed, the multilayer reflective film 21 or the like is formed on the main surface on which the transfer pattern is formed. Alternatively, a protective film 22 may be further formed to form a substrate 20 with a multilayer reflective film, and further a phase shift film 24 may be formed on the protective film 22 to form a reflective mask blank 30.

Reference Signs List 10 mask blank substrate 20 substrate with multilayer reflective film 21 multilayer reflective film 22 protective film 23 back conductive film 24 phase shift film 25 etching mask film 26 multilayer film for mask blank 27 phase shift film pattern 30 reflective mask blank 40 reflective mask

Claims (13)

A reflective mask blank in which a multilayer reflective film and a phase shift film for shifting the phase of EUV light are formed in this order on a substrate,
In a 1 μm × 1 μm region on the surface of the phase shift film, a root mean square roughness (Rms) obtained by an atomic force microscope is 0.50 nm or less, and a power spectrum density at a spatial frequency of 10 to 100 μm ^−1. reflective mask blank, wherein the integral value of is 360 nm ³ or less. The reflective mask blank according to claim 1 wherein the integrated value, characterized in that at 250 nm ³ or less.   The reflective mask blank according to claim 1, wherein a protective film is formed on the multilayer reflective film.   The reflective mask blank according to any one of claims 1 to 3, wherein the outermost surface layer of the phase shift film is a tantalum-based material layer, a chromium-based material layer, or a ruthenium-based material layer.   The reflective mask blank according to any one of claims 1 to 4, further comprising an etching mask film disposed in contact with a surface of the phase shift film opposite to the substrate.   The root-mean-square roughness (Rms) measured by an atomic force microscope in a 1 μm × 1 μm region on the surface of the phase shift film is 0.40 nm or less, according to any one of claims 1 to 5. Reflective mask blank. A reflective mask in which a multilayer reflective film and a phase shift film pattern for shifting the phase of EUV light are formed in this order on a substrate,
In a 1 μm × 1 μm region on the surface of the phase shift film pattern, a power spectrum having a root-mean-square roughness (Rms) measured by an atomic force microscope of 0.50 nm or less and a spatial frequency of 10 to 100 μm ⁻¹ . A reflective mask, wherein the integrated value of the density is 360 nm ³ or less. The integral value is reflective mask according to claim 7, characterized in that at 250 nm ³ or less. The reflective mask according to claim 7 or 8, characterized in that the protective film on the multilayer reflective film is formed. In a 1 μm × 1 μm region on the surface of the multilayer reflective film or the protective film, a root-mean-square roughness (Rms) measured by an atomic force microscope is 0.15 nm or less, and a spatial frequency is 10 to 100 μm ^−1. the reflective mask according to any one of claims 7-9, wherein the power spectral density of is 7 nm ⁴ or less. The reflective mask according to any one of claims 7 to 10 , wherein the outermost surface layer of the phase shift film pattern is a tantalum-based material layer, a chromium-based material layer, or a ruthenium-based material layer.   The root mean square roughness (Rms) measured by an atomic force microscope in a 1 μm × 1 μm region on the surface of the phase shift film is 0.40 nm or less, according to any one of claims 7 to 11. Reflective mask. A method for manufacturing a semiconductor device, comprising: performing a lithography process using an exposure apparatus using the reflective mask according to any one of claims 7 to 12 to form a transfer pattern on an object to be transferred.