JP2024142243A - Substrate with conductive film, substrate with multilayer reflective film, reflective mask blank, reflective mask, and method for manufacturing semiconductor device - Google Patents

Abstract

[Problem] To provide a substrate with a conductive film that can be firmly attached to an electrostatic chuck and easily detached from the electrostatic chuck. [Solution] A substrate with a conductive film is provided on a first main surface of the substrate, and the crystallite size of the conductive film is 2.5 nm or more, calculated from the diffraction angle 2θmax at which the diffraction intensity is maximized by 2θ/ω measurement using X-ray diffraction (ω is the angle of incidence of X-rays in X-ray diffraction measurement) in the range of diffraction angle 2θ of 30 degrees or more and 90 degrees or less. [Selected Figure] Figure 1

Description

The present invention relates to a substrate with a conductive film, a substrate with a multilayer reflective film, a reflective mask blank, a reflective mask, and a method for manufacturing a semiconductor device.

In general, in the manufacturing process of semiconductor devices, fine patterns are formed using photolithography. To form these fine patterns, a number of transfer masks, also known as photomasks, are usually used. These transfer masks are generally formed by providing a fine pattern made of a metal thin film or the like on a glass substrate, and photolithography is also used to manufacture these transfer masks.

In the manufacture of a transfer mask by photolithography, a mask blank having a thin film (e.g., a light-shielding film) for forming a transfer pattern (mask pattern) on a substrate such as a glass substrate is used. The manufacture of a transfer mask using this mask blank is carried out through a drawing process in which a desired pattern is drawn on a resist film formed on the mask blank, a development process in which the resist film is developed after drawing to form a desired resist pattern, an etching process in which the thin film is etched using the resist pattern as a mask, and a process in which the remaining resist pattern is peeled off and removed. In the development process, after the desired pattern is drawn on the resist film formed on the mask blank, a developer is supplied to dissolve the parts of the resist film that are soluble in the developer, forming a resist pattern. In the etching process, the resist pattern is used as a mask to remove the exposed parts of the thin film where the resist pattern is not formed by dry etching or wet etching, thereby forming the desired mask pattern on the substrate. In this way, a transfer mask is completed.

Known types of transfer masks include a binary type mask having a light-shielding film pattern made of a chromium-based material on a conventional substrate, as well as a phase-shift type mask.
In recent years, in the semiconductor industry, with the increasing integration of semiconductor devices, fine patterns that exceed the transfer limit of conventional photolithography using ultraviolet light are required. To enable the formation of such fine patterns, there is EUV lithography, an exposure technology using extreme ultraviolet (hereinafter referred to as "EUV") light. Here, EUV light refers to light in the wavelength band of the soft X-ray region or the vacuum ultraviolet region, and light with a wavelength of about 0.2 to 100 nm. In this specification, EUV light refers to light including light with a wavelength of 13.5 nm, and can be light with a wavelength of 13 nm to 14 nm, more specifically, light with a wavelength of 13.5 nm. In this specification, light includes not only visible light but also electromagnetic waves. A reflective mask is used as a mask in this EUV lithography. In such a reflective mask, a multilayer reflective film that reflects the EUV light, which is the exposure light, is formed on a substrate, and an absorber film that absorbs the EUV light is formed in a pattern on the multilayer reflective film.

The reflective mask is supported by an electrostatic chuck in an exposure device, for example, when transferring a pattern onto a semiconductor substrate. On the other hand, the substrate used in the reflective mask blank or reflective mask is made of an insulating glass substrate or the like. For this reason, a conductive film (rear conductive film) is formed on the rear surface of the substrate of the reflective mask blank or reflective mask. As a conventional technique, for example, Patent Document 1 discloses a mask substrate having a rear surface coating of a material with a higher dielectric constant than the substrate, such as silicon, molybdenum, chromium, chromium oxynitride, or TaSi. Patent Document 2 discloses a conductive film-coated substrate on which an amorphous chromium-based conductive film is formed.

Special Publication No. 2003-501823 JP 2015-215602 A

However, if the reflective mask placed on a movable stage using an electrostatic chuck is misaligned during pattern transfer, it becomes difficult to transfer the pattern with high accuracy. Therefore, it is preferable that the back conductive film of the reflective mask is firmly fixed to the electrostatic chuck. On the other hand, if the back conductive film is firmly fixed to the electrostatic chuck, particles originating from the back film may be generated when the reflective mask is detached from the electrostatic chuck. If these particles remain on the electrostatic chuck, when the substrate of another reflective mask is attracted to the electrostatic chuck, the flatness of the reflective mask may decrease, making it difficult to transfer the pattern with high accuracy. In addition, these particles may adhere to the reflective mask and cause defects.

The present invention has been made in consideration of these conventional problems, and has as its object, first, to provide a substrate with a conductive film that can be firmly attached to an electrostatic chuck and easily detached from the electrostatic chuck, and that can suppress the generation of particles due to attachment and detachment to the electrostatic chuck.
Secondly, the present invention provides a multilayer reflective film-coated substrate, a reflective mask blank, and a reflective mask using the above-mentioned conductive film-coated substrate, and thirdly, a method for manufacturing a semiconductor device using this reflective mask.

The present inventors have conducted intensive research to solve the conventional problems and have completed the following invention.
(Configuration 1)
A substrate with a conductive film, the substrate having a conductive film provided on a first main surface of the substrate, characterized in that the crystallite size of the conductive film is 2.5 nm or more, calculated from a diffraction angle 2θmax at which a diffraction intensity obtained by 2θ/ω measurement using X-ray diffraction is maximized in a diffraction angle 2θ range of 30 degrees or more and 90 degrees or less.

(Configuration 2)
2. The substrate with a conductive film according to claim 1, wherein the conductive film contains tantalum or chromium.
(Configuration 3)
3. The substrate with a conductive film according to claim 1, wherein the conductive film contains 95 atomic % or more of tantalum.

(Configuration 4)
3. The substrate with a conductive film according to claim 1, wherein the conductive film contains tantalum and nitrogen in a total amount of 95 atomic % or more.
(Configuration 5)
3. The substrate with a conductive film according to claim 1, wherein the conductive film is formed in contact with the substrate.

(Configuration 6)
3. The substrate with a conductive film according to claim 1, wherein the conductive film has a compressive stress.

(Configuration 7)
A substrate with a multilayer reflective film, characterized in that a multilayer reflective film in which high refractive index layers and low refractive index layers are alternately stacked is formed on a second main surface opposite to the first main surface of the substrate with a conductive film according to configuration 1 or 2.

(Configuration 8)
A reflective mask blank comprising an absorber film formed on the multilayer reflective film of the multilayer reflective film-coated substrate according to Configuration 7.
(Configuration 9)
9. The reflective mask blank according to structure 8, wherein a protective film is formed between the multilayer reflective film and the absorber film.

(Configuration 10)
A reflective mask having an absorber film pattern obtained by patterning the absorber film of the reflective mask blank according to configuration 8 by etching.

(Configuration 11)
11. A method for manufacturing a semiconductor device, comprising the step of transferring the absorber film pattern onto a transfer target by exposure using the reflective mask according to configuration 10.

According to the present invention, it is possible to provide a substrate with a conductive film that can be firmly attached to an electrostatic chuck and easily detached from the electrostatic chuck, and that can suppress the generation of particles due to attachment and detachment to the electrostatic chuck.
Furthermore, according to the present invention, it is possible to provide a multilayer reflective film coated substrate, a reflective mask blank, and a reflective mask, which use the above-mentioned conductive film coated substrate.

Furthermore, according to the present invention, a method for manufacturing a semiconductor device using this reflective mask can be provided. By using this reflective mask to transfer a pattern, it is possible to perform highly accurate pattern transfer without causing misalignment of the reflective mask placed on a movable stage using an electrostatic chuck during pattern transfer.

1 is a cross-sectional view showing one embodiment of a conductive film-attached substrate of the present invention. 1 is a cross-sectional view showing one embodiment of a multilayer reflective film-coated substrate of the present invention. 1 is a cross-sectional view showing one embodiment of a reflective mask blank of the present invention. FIG. 2 is a cross-sectional view showing another embodiment of the reflective mask blank of the present invention. FIG. 2 is a cross-sectional view showing another embodiment of the reflective mask blank of the present invention. 1 is a cross-sectional view showing an embodiment of a reflective mask of the present invention.

Hereinafter, an embodiment of the present invention will be described in detail.
[Substrate with conductive film]
First, the conductive film-attached substrate of the present invention will be described.
FIG. 1 is a cross-sectional view showing one embodiment of a substrate with a conductive film of the present invention.
1, in the conductive-film-attached substrate 10 of this embodiment, a conductive film 2 is provided on a first main surface (the back surface of the substrate 1 in the illustrated state) of a substrate 1. In this embodiment, the conductive film 2 is formed in contact with the substrate 1.

The substrate with a conductive film of the present invention is characterized in that the crystallite size of the conductive film is 2.5 nm or more, calculated from the diffraction angle 2θmax at which the diffraction intensity obtained by 2θ/ω measurement (2θ/ω scan) using X-ray diffraction is maximum in the diffraction angle 2θ range of 30 degrees or more and 90 degrees or less.
The above ω is the angle of incidence of X-rays in the X-ray diffraction measurement.

<Substrate>
Substrate 1 has two mutually opposing main surfaces and four end surfaces. When the conductive film-coated substrate of the present invention is used, for example, in a reflective mask blank for EUV exposure, the substrate 1 is preferably a glass substrate, and in particular, in order to prevent distortion of the pattern due to heat during exposure, a substrate having a low thermal expansion coefficient within the range of 0±1.0×10 ^-7 /° C., more preferably within the range of 0±0.3×10 ^-7 /° C., is preferably used. Examples of materials having a low thermal expansion coefficient within this range include SiO ₂ -TiO ₂ glass and multi-component glass ceramics.

The main surface of the glass substrate on which the transfer pattern is formed is surface-processed to have a high degree of flatness in order to improve at least the pattern transfer accuracy and positional accuracy. In the case of EUV exposure, the flatness is preferably 0.1 μm or less, and particularly preferably 0.05 μm or less, in an area of 142 mm × 142 mm on the main surface of the glass substrate on which the transfer pattern is formed. In this specification, flatness is a value that represents the warpage (deformation amount) of the surface indicated by TIR (Total Indicated Reading). This value is the absolute value of the height difference between the highest position on the surface of the substrate 1 above the focal plane, and the lowest position on the surface of the substrate 1 below the focal plane, with the plane determined by the least squares method based on the surface of the substrate 1 as the focal plane.

In addition, in the case of EUV exposure, as described above, a material having a low thermal expansion coefficient such as SiO ₂ -TiO ₂ -based glass is preferably used as the glass substrate. For the purpose of reducing the surface roughness of the glass substrate or reducing defects on the surface of the glass substrate, an underlayer may be formed on the main surface of the glass substrate on which the transfer pattern is formed, as necessary. As the material for such an underlayer, a material that does not need to be transparent to the exposure light and that provides high smoothness and good defect quality when the surface of the underlayer is precision polished is preferably selected. For example, Si or a silicon compound containing Si (e.g., SiO ₂ , SiON, etc.) provides high smoothness and good defect quality when precision polished, and is therefore preferably used as the material for the underlayer. Si is particularly preferred as the material for the underlayer. By using such an underlayer, a high smoothness of 0.1 nm or less in root mean square roughness (Rq) can be achieved as the surface roughness of the glass substrate.

The surface of the underlayer is preferably precision-polished to have a smoothness required for a reflective mask blank substrate. The surface of the underlayer is desirably precision-polished to have a root-mean-square roughness (Rq) of 0.15 nm or less, particularly preferably 0.1 nm or less. In addition, in consideration of the influence on the surface of the multilayer reflective film formed on the underlayer, the surface of the underlayer is desirably precision-polished to have a relationship with the maximum height (Rmax) of preferably 2 to 10, particularly preferably 2 to 8, such that Rmax/Rq is 2 to 10.
The thickness of the underlayer is preferably in the range of, for example, 10 nm to 300 nm.

<Conductive film>
The conductive film 2 may be a single layer. This simplifies the film formation process. The surface of the single layer conductive film 2 opposite to the substrate 1 may be oxidized. That is, the conductive film 2 may have a surface oxide layer with a very small thickness on the surface opposite to the substrate 1. The thickness of the surface oxide layer may be 4 nm or less, preferably 2 nm or less, and more preferably 1 nm or less. This makes it possible to further suppress particle generation during electrostatic chuck dechucking. The conductive film 2 may also be a laminated film including a plurality of layers. In this case, for example, the oxygen content of the top layer included in the laminated film can be made higher than the other layers. That is, the top layer can be the layer with the highest oxygen content. This makes it possible to further suppress particle generation during electrostatic chuck dechucking. The top layer is preferably, for example, 5 nm or more.
The thickness of the conductive film 2 is not particularly limited, but is preferably 10 nm or more, and more preferably 20 nm or more. The thickness is preferably 500 nm or less, more preferably 200 nm or less, and even more preferably 100 nm or less. The method for forming the conductive film 2 is not particularly limited, but magnetron sputtering, ion beam sputtering, and the like are usually suitable.

In addition, the interface region of the conductive film 2 with the substrate 1 (substrate interface region) and the surface region of the conductive film 2 on the opposite side of the substrate 1 are both compositionally graded regions in which the composition ratio of the conductive film 2 changes continuously. Therefore, the above-mentioned conductive film 2 being made of a single layer also includes the case where the conductive film 2 is made of a compositionally graded region (surface region and substrate interface region) and an internal region other than the compositionally graded region (a region in which the composition ratio is uniform in the film thickness direction). Here, the composition ratio being uniform in the film thickness direction means that the difference between each of the constituent elements in the film thickness direction is so small that it can be ignored, for example, the difference between each of the constituent elements is 3 atomic % or less.

The substrate interface region is a region that extends from the interface between the conductive film 2 and the substrate 1 toward the surface opposite the substrate 1 (i.e., the surface region) to a thickness of, for example, more than 0 nm and not more than 5 nm. The thickness of the substrate interface region is more preferably not more than 4 nm, and even more preferably not more than 3 nm.

The surface region is a region that extends from the surface of the conductive film 2 opposite the substrate 1 toward the substrate 1 to a thickness of, for example, more than 0 nm and not more than 5 nm. The thickness of the surface region is more preferably not more than 4 nm, and even more preferably not more than 3 nm.

In the present invention, the material of the conductive film 2 is not particularly limited, but preferable examples include tantalum-based materials and chromium-based materials.
The tantalum-based material may be tantalum (Ta) alone, or tantalum containing one or more elements selected from carbon (C), nitrogen (N), oxygen (O), boron (B), hydrogen (H), and the like.
The chromium-based material may be chromium (Cr) alone, or chromium containing one or more elements selected from carbon (C), nitrogen (N), oxygen (O), boron (B), hydrogen (H), and the like.

In particular, since the above-mentioned tantalum-based materials have high cleaning resistance, in the present invention, it is preferable that the conductive film 2 is made of a tantalum-based material. Furthermore, from the viewpoint of chemical resistance and abrasion resistance, it is more preferable that the metal contained in the conductive film 2 is only tantalum.

When the conductive film 2 is made of a tantalum-based material, specific examples include TaN, TaB, and TaBN.
When the conductive film 2 contains tantalum, the content is preferably 95 atomic % or more. When the conductive film 2 contains tantalum and nitrogen, the total content of tantalum and nitrogen is preferably 95 atomic % or more.

In addition, in the present invention, it is preferable that the conductive film 2 has compressive stress. When the conductive film 2 has compressive stress, it is possible to improve the reduction of warping of the substrate 1 caused by the multilayer reflective film.

As described above, the conductive film-attached substrate of the present invention is characterized in that the crystallite size of the conductive film is 2.5 nm or more, calculated from the diffraction angle 2θmax at which the diffraction intensity obtained by 2θ/ω measurement using X-ray diffraction is maximum, in the diffraction angle 2θ range of 30 degrees or more and 90 degrees or less.

In the present invention, the X-ray diffraction measurement is an out-of-plane measurement using a 2θ/ω scan, and the diffraction angle 2θ is measured by irradiating X-rays onto the surface of the conductive film 2 at an incidence angle ω.

A specific method for measuring X-ray diffraction in the present invention will now be described.
An X-ray diffraction apparatus was used to perform 2θ/ω scan measurement on the conductive film 2. The measurement area (measurement point) was one point within a 20 mm × 20 mm area including the center of the conductive film. The X-ray source used was a CuKα ₁ ray (wavelength: 1.5405 Å) with an output of 45 kV-200 mA, and data was obtained by measurement under conditions of a step width of 0.1° and a scan speed of 1°/min.

In the present invention, the crystallite size of the conductive film 2 is calculated as follows.
The crystallite size D was calculated from the half-width β (rad) of the diffraction peak having the maximum diffraction intensity in the diffraction angle 2θ range of 30 degrees or more and 90 degrees or less, using the following Scherrer formula (Formula (1)).
D=K・λ/(β・cos(u/2))...(1)
where K is the Scherrer constant of 0.9, and λ is the wavelength of X-rays (CuKα ₁ )=1.5405 Å.

Note that u was obtained by fitting the diffraction spectrum within the range of diffraction angle 2θmax ±2 (degrees) where the diffraction intensity is maximum in the range of diffraction angle 2θmax of 30 degrees ≦ 2θ ≦ 90 degrees using the Gaussian function below (Equation (2)) by the least squares method, and the half-width β was calculated from σ obtained by this fitting.

The half-width β was calculated from the following formula (formula (3)) using the σ obtained by the above fitting.

In the present invention, the crystallite size of the conductive film 2 is set to 2.5 nm or more, thereby increasing the static friction coefficient of the conductive film 2, and therefore the conductive film-attached substrate 10 can be prevented from slipping on the electrostatic chuck, and the conductive film-attached substrate 10 can be more firmly fixed to the electrostatic chuck. Furthermore, since the crystallite size of the conductive film 2 is set to 2.5 nm or more, the actual contact area between the conductive film 2 and the electrostatic chuck can be reduced, and the conductive film-attached substrate 10 can be more easily detached from the electrostatic chuck. Therefore, the generation of particles due to film peeling when the conductive film-attached substrate 10 is detached from the electrostatic chuck can be suppressed.
In order to prevent the surface roughness of the conductive film 2 from becoming too large, the crystallite size of the conductive film 2 is preferably 25 nm or less, more preferably 23 nm or less, and further preferably 22 nm or less.

As described above, the substrate with a conductive film of the present invention can be firmly attached to the electrostatic chuck and easily detached from the electrostatic chuck, thereby suppressing the generation of particles due to attachment and detachment to the electrostatic chuck.
Therefore, the same effects as above can be obtained in a multilayer reflective film coated substrate, a reflective mask blank, and a reflective mask (details of which will be described later) using the conductive film coated substrate of the present invention.

[Substrate with multilayer reflective film]
Next, the multilayer reflective film coated substrate of the present invention will be described.
FIG. 2 is a cross-sectional view showing one embodiment of a multilayer reflective film-coated substrate of the present invention.
As shown in FIG. 2, a multilayer reflective film-coated substrate 20 according to one embodiment of the present invention has a multilayer reflective film 3 formed on a second main surface (the surface of substrate 1 in the illustrated state) opposite to the first main surface of the conductive film-coated substrate 10, which reflects EUV light, which is the exposure light.

The multilayer reflective film-coated substrate 20 of this embodiment is produced by forming a multilayer reflective film 3 that reflects exposure light, for example EUV light, on the second main surface of the conductive film-coated substrate 10.

The multilayer reflective film 3 is a multilayer film in which low refractive index layers and high refractive index layers are alternately laminated, and generally, a multilayer film in which a thin film of a heavy element or its compound and a thin film of a light element or its compound are alternately laminated for about 30 to 60 periods is used.
For example, as a multilayer reflective film for EUV light with a wavelength of 13 to 14 nm, a Mo/Si periodic laminated film in which Mo films and Si films are alternately laminated for about 40 periods is preferably used. Other multilayer reflective films used in the EUV light region include Ru/Si periodic multilayer films, Mo/Be periodic multilayer films, Mo compound/Si compound periodic multilayer films, Si/Nb periodic multilayer films, Si/Mo/Ru periodic multilayer films, Si/Mo/Ru/Mo periodic multilayer films, and Si/Ru/Mo/Ru periodic multilayer films. The material may be appropriately selected according to the exposure wavelength.

Usually, in order to protect the multilayer reflective film during patterning or pattern correction of the absorber film, it is preferable to provide a protective film (sometimes called a capping layer) on the multilayer reflective film 3. Such a protective film is formed, for example, from a material containing ruthenium as a main component. Examples of materials containing ruthenium as a main component include Ru metal alone, Ru alloys containing at least one metal selected from titanium (Ti), niobium (Nb), rhodium (Rh), molybdenum (Mo), zirconium (Zr), yttrium (Y), boron (B), lanthanum (La), cobalt (Co), chromium (Cr) and rhenium (Re), and materials containing nitrogen therein. Incidentally, containing substance A as a main component means containing substance A at 50% or more.
The thickness of the protective film is preferably, for example, 1 nm or more, and is preferably 5 nm or less.

The deposition method for the multilayer reflective film 3 and the protective film is not particularly limited, but typically ion beam sputtering or magnetron sputtering is preferred.

[Reflective mask blank]
Next, the reflective mask blank of the present invention will be described.
FIG. 3 is a cross-sectional view showing one embodiment of the reflective mask blank of the present invention.
As shown in FIG. 3 , a reflective mask blank 30 according to one embodiment of the present invention has an absorber film 5 formed on the multilayer reflective film 3 of the multilayer reflective film-coated substrate 20 .

The reflective mask blank 30 is produced by depositing an absorber film 5 that absorbs EUV light on the multilayer reflective film 3 (or the protective film, if any) of the multilayer reflective film-coated substrate 20.

The absorber film 5 has a function of absorbing, for example, EUV light, which is exposure light, and may have a desired reflectance difference between the reflected light by the multilayer reflective film 3 (the protective film when the multilayer reflective film 3 has the protective film on its surface) and the reflected light by the absorber film pattern 5a (see FIG. 6) in the reflective mask 60 (see FIG. 6) produced using the reflective mask blank. For example, the reflectance of the absorber film 5 for EUV light is selected between 0.1% or more and 40% or less. In addition to the reflectance difference, the absorber film 5 may have a desired phase difference between the reflected light by the multilayer reflective film 3 (the protective film when the multilayer reflective film 3 has the protective film on its surface) and the reflected light by the absorber film pattern 5a. When the absorber film 5 in the reflective mask blank has a desired phase difference between the reflected light by the multilayer reflective film 3 (the protective film when the multilayer reflective film 3 has the protective film on its surface) and the reflected light by the absorber film pattern 5a, the absorber film 5 in the reflective mask blank may be referred to as a phase shift film. When improving contrast by providing a desired phase difference between the light reflected by the multilayer reflective film 3 (or the protective film if the multilayer reflective film 3 has the protective film on its surface) and the light reflected by the absorber film pattern 5a, the phase difference is preferably set in the range of 150 degrees to 310 degrees, and the reflectance of the absorber film 5 is preferably set to 3% or more and 40% or less.

The absorber film 5 may be a single layer or a laminated structure. In the case of a laminated structure, it may be a laminated film of the same material or a laminated film of different materials. The laminated film may have a material or composition that changes stepwise and/or continuously in the film thickness direction. When the absorber film 5 is a laminated film, the absorber film 5 may include, for example, a layer (buffer layer) having etching selectivity with respect to the protective film at a position closest to the substrate in the film thickness direction.

The material of the absorber film 5 is not particularly limited, so long as it has the function of absorbing EUV light, can be processed by etching or the like (preferably by dry etching with a chlorine (Cl)-based gas and/or a fluorine (F)-based gas), and has a high etching selectivity with respect to the multilayer reflective film 3 (or the protective film, if the multilayer reflective film 3 has the protective film on its surface). As a material having such a function, at least one metal selected from palladium (Pd), silver (Ag), platinum (Pt), gold (Au), iridium (Ir), tungsten (W), chromium (Cr), cobalt (Co), manganese (Mn), tin (Sn), tantalum (Ta), vanadium (V), nickel (Ni), hafnium (Hf), iron (Fe), copper (Cu), tellurium (Te), zinc (Zn), magnesium (Mg), germanium (Ge), aluminum (Al), rhodium (Rh), ruthenium (Ru), molybdenum (Mo), niobium (Nb), titanium (Ti), zirconium (Zr), yttrium (Y), and silicon (Si), an alloy containing two or more metals, or a compound thereof can be preferably used. The compound may contain oxygen (O), nitrogen (N), carbon (C), and/or boron (B) in the above metal or alloy.

The thickness of the absorber film 5 is preferably in the range of, for example, about 30 nm to 100 nm. There are no particular limitations on the method for forming the absorber film 5, but magnetron sputtering or ion beam sputtering is usually preferred.

FIG. 4 is a cross-sectional view showing another embodiment of the reflective mask blank of the present invention.
4, the reflective mask blank 40 of this embodiment has the above-mentioned protective film 4 on the surface of the multilayer reflective film 3, that is, the protective film 4 is formed between the multilayer reflective film 3 and the absorber film 5. The protective film 4 is as described above.

FIG. 5 is a cross-sectional view showing another embodiment of the reflective mask blank of the present invention.
As shown in FIG. 5, in the reflective mask blank 50 of this embodiment, an etching mask film 6 is formed on the absorber film 5 .

The etching mask film 6 has a mask function when the absorber film 5 is patterned, and is made of a material having a different etching selectivity from the material of the top layer of the absorber film 5. For example, when the absorber film 5 is Ta alone or a material containing Ta, the etching mask film 6 can be made of a material such as chromium, a chromium compound, or silicon or a silicon compound. Examples of chromium compounds include materials containing Cr and at least one element selected from N, O, C, and H. Examples of silicon compounds include materials containing Si and at least one element selected from N, O, C, and H, and materials such as metal silicon (metal silicide) and metal silicon compound (metal silicide compound) containing metal in silicon or silicon compound. Examples of metal silicon compounds include materials containing metal, Si, and at least one element selected from N, O, C, and H.
Furthermore, when the absorber film 5 is a laminated film of a material containing Ta and a material containing Cr from the multilayer reflective film 3 side, the material of the etching mask film 6 can be selected from silicon, a silicon compound, a metal silicide, a metal silicide compound, etc., which have etching selectivity different from that of the material containing Cr.

In addition, the reflective mask blank 50 according to this embodiment (as well as the above-mentioned reflective mask blanks 30 and 40) can also be configured such that the absorber film 5 is constructed as a laminate film of a top layer and other layers made of materials with different etching selectivities, with the top layer functioning as an etching mask film for the other layers.

As described above, the absorber film 5 in the reflective mask blanks 30, 40, and 50 according to the above-described embodiments is not limited to a single layer film, but can be composed of a laminate film of the same material or a laminate film of different materials, and further can be composed of a laminate film of the absorber film 5 of the above-described laminate film or single layer film and a film that functions as an etching mask film.

The reflective mask blanks 30, 40, and 50 according to the above-mentioned embodiments also include an embodiment in which a resist film is formed on the absorber film 5 (or on the etching mask film 6 in the case where the reflective mask blank 50 has an etching mask film 6 on the absorber film 5). Such a resist film is used when patterning the absorber film 5 in the reflective mask blank by photolithography.

[Reflective mask]
The present invention also provides a reflective mask produced using the above-mentioned reflective mask blank 30 or the like.
FIG. 6 is a cross-sectional view showing an embodiment of the reflective mask of the present invention.
As shown in FIG. 6, a reflective mask 60 of this embodiment has an absorber film pattern 5a obtained by patterning the absorber film 5 of the above-mentioned reflective mask blank 40 by etching, for example.

The most suitable method for patterning the absorber film 5, which will become the transfer pattern in the reflective mask blank 40, is photolithography. That is, a resist for electron beam lithography is applied to the above-mentioned reflective mask blank 40, and a resist film is formed by baking, and the resist film is lithographed and developed using an electron beam lithography device, forming a resist pattern corresponding to the transfer pattern on the resist film. After that, the absorber film 5 is patterned using this resist pattern as a mask to form an absorber film pattern 5a, thereby producing the reflective mask 60 shown in FIG. 6.

The protective film 4 in the area exposed by forming the absorber film pattern 5a may be eventually removed, but if it remains, it does not have to be removed as long as it does not affect the function as a reflective mask. Also, when manufacturing a reflective mask using a reflective mask blank 50 having a configuration including the above-mentioned etching mask film 6, the etching mask film 6 may be eventually removed, but if it remains, it does not have to be removed as long as it does not affect the function as a reflective mask.

[Method of Manufacturing Semiconductor Device]
Furthermore, by using the above-mentioned reflective mask 60 of the present invention to expose and transfer the above-mentioned transfer pattern (absorber film pattern 5a) to a transfer target, for example, a resist film on a semiconductor substrate, a high-quality semiconductor device with few defects can be manufactured. By performing pattern transfer using the reflective mask 60 using the conductive film-coated substrate of the present invention, highly accurate pattern transfer can be performed without causing positional deviation of the reflective mask 60 placed on a movable stage using an electrostatic chuck during pattern transfer.

As described above in detail, according to the present invention, it is possible to provide a substrate with a conductive film that can be firmly attached to an electrostatic chuck and easily detached from the electrostatic chuck, and that can suppress the generation of particles due to attachment and detachment to the electrostatic chuck.
Furthermore, according to the present invention, it is possible to provide a multilayer reflective film coated substrate, a reflective mask blank, and a reflective mask, which use the above-mentioned conductive film coated substrate.

Furthermore, by using this reflective mask to transfer patterns through exposure, it is possible to perform highly accurate pattern transfer, enabling the manufacture of high-quality semiconductor devices with few defects.

The following examples further illustrate the present invention.
Example 1
A _{SiO2- TiO2} -based glass substrate (a 6-inch square substrate with dimensions of approximately 152.0 mm x 152.0 mm and a thickness of approximately 6.35 mm) was prepared as the substrate. This glass substrate was mechanically polished to have a smooth surface with a root-mean-square roughness (Rq) of 0.25 nm and a flatness of 100 nm or less. The surface roughness was measured with an atomic force microscope (AFM) and the measurement area was 1 μm x 1 μm.

First, a Ta conductive film made of tantalum was formed on the back surface of the substrate. The substrate was placed in a sputtering device, and a tantalum (Ta) target was used, and a xenon (Xe) gas was used as the sputtering gas, to form a Ta film with a thickness of 70 nm by sputtering.

The crystallite size of the Ta conductive film formed above was 21.3 nm, calculated from the diffraction angle 2θmax at which the diffraction intensity obtained by 2θ/ω measurement using X-ray diffraction was maximum in the diffraction angle 2θ range of 30 degrees to 90 degrees. Specific measurement and calculation methods were as described above.

The substrate with the conductive film obtained in this manner was attached to and detached from the electrostatic chuck 100 times, and then the conductive film was inspected for defects of 1.0 μm or more using a defect inspection device.

Next, on the surface of another substrate with a conductive film prepared in exactly the same manner as above, a Si film (film thickness: 4.2 nm) and a Mo film (film thickness: 2.8 nm) were laminated 40 times using an ion beam sputtering device, with each film being one period, and finally a Si film (film thickness: 4 nm) was formed, and a protective film made of Ru (film thickness: 2.5 nm) was further formed on top of that to obtain a substrate with a multilayer reflective film.

Next, a DC magnetron sputtering device was used to form an absorber film consisting of a laminated film of a TaBN film (film thickness: 56 nm) and a TaBO film (film thickness: 14 nm) on the protective film of the multilayer reflective film-coated substrate. In this way, a reflective mask blank was obtained.

Next, a reflective mask was produced using this reflective mask blank.
First, a resist for electron beam lithography was applied onto a reflective mask blank by spin coating and baked to form a resist film. A predetermined mask pattern was written onto the resist film by electron beam and developed to form a resist pattern.

Using this resist pattern as a mask, the TaBO film of the absorber film was etched away with a fluorine-based gas ( _CF4 gas) and the TaBN film was etched away with a chlorine-based gas ( _Cl2 gas) to form an absorber film pattern on the protective film.
Furthermore, the resist pattern remaining on the absorber film pattern was removed with hot sulfuric acid to obtain a reflective mask.

The reflective mask of this embodiment obtained in this way was set on a movable stage by an electrostatic chuck in the exposure device, and the pattern was transferred onto a semiconductor substrate on which a resist film had been formed.

Example 2
A TaN conductive film made of tantalum and nitrogen was formed on the back surface of a substrate prepared in the same manner as in Example 1. The substrate was placed in a sputtering device, and a tantalum (Ta) target was used, and a mixed gas of xenon (Xe) and nitrogen ( _N2 ) (flow ratio (%) Xe: _N2 = 60:40) was used as the sputtering gas, to form a TaN film (composition ratio Ta:N = 81 atomic %: 19 atomic %) with a thickness of 70 nm by reactive sputtering.

For the TaN conductive film formed, the crystallite size of the conductive film was 2.9 nm, calculated from the diffraction angle 2θmax at which the diffraction intensity obtained by 2θ/ω measurement using X-ray diffraction was maximum in the diffraction angle 2θ range of 30 degrees to 90 degrees.

The substrate with the conductive film obtained in the above manner was subjected to 100 repeated attachment and detachment to the electrostatic chuck in the same manner as in Example 1, and then the conductive film was inspected for defects of 1.0 μm or more using a defect inspection device.

Next, on the surface of another substrate with a conductive film prepared in exactly the same manner as above, opposite the conductive film, a multilayer reflective film, a protective film and an absorber film were formed in that order in the same manner as in Example 1 to obtain a reflective mask blank.
Next, using this reflective mask blank, a reflective mask of Example 2 was produced in the same manner as in Example 1.

The reflective mask of Example 2 thus obtained was set on a movable stage by an electrostatic chuck in an exposure device, and a pattern was transferred onto a semiconductor substrate on which a resist film had been formed.

Example 3
A TaN conductive film made of tantalum and nitrogen was formed on the back surface of a substrate prepared in the same manner as in Example 1. The substrate was placed in a sputtering device, and a tantalum (Ta) target was used, and a mixed gas of xenon (Xe) and nitrogen ( _N2 ) (flow ratio (%) Xe: _N2 = 47:53) was used as the sputtering gas, to form a TaN film (composition ratio Ta:N = 71 atomic %: 29 atomic %) with a thickness of 70 nm by reactive sputtering.

For the TaN conductive film formed, the crystallite size of the conductive film was 7.0 nm, calculated from the diffraction angle 2θmax at which the diffraction intensity obtained by 2θ/ω measurement using X-ray diffraction was maximum in the diffraction angle 2θ range of 30 degrees to 90 degrees.

The substrate with the conductive film obtained in the above manner was subjected to 100 repeated attachment and detachment to the electrostatic chuck in the same manner as in Example 1, and then the conductive film was inspected for defects of 1.0 μm or more using a defect inspection device.

Next, on the surface of another substrate with a conductive film prepared in exactly the same manner as above, opposite the conductive film, a multilayer reflective film, a protective film and an absorber film were formed in that order in the same manner as in Example 1 to obtain a reflective mask blank.
Next, using this reflective mask blank, a reflective mask of Example 3 was produced in the same manner as in Example 1.

The reflective mask of Example 3 thus obtained was set on a movable stage by an electrostatic chuck in an exposure device, and a pattern was transferred onto a semiconductor substrate on which a resist film had been formed.

Example 4
A TaN conductive film made of tantalum and nitrogen was formed on the back surface of a substrate prepared in the same manner as in Example 1. The substrate was placed in a sputtering device, and a tantalum (Ta) target was used, and a mixed gas of xenon (Xe) and nitrogen ( _N2 ) (flow ratio (%) Xe: _N2 = 39:61) was used as the sputtering gas, to form a TaN film (composition ratio Ta:N = 65 atomic %: 35 atomic %) with a thickness of 70 nm by reactive sputtering.

For the TaN conductive film formed, the crystallite size of the conductive film calculated from the diffraction angle 2θmax at which the diffraction intensity obtained by 2θ/ω measurement using X-ray diffraction is maximum in the diffraction angle 2θ range of 30 degrees or more and 90 degrees or less was 16.8 nm.

The substrate with the conductive film obtained in the above manner was subjected to 100 repeated attachment and detachment to the electrostatic chuck in the same manner as in Example 1, and then the conductive film was inspected for defects of 1.0 μm or more using a defect inspection device.

Next, on the surface of another substrate with a conductive film prepared in exactly the same manner as above, opposite the conductive film, a multilayer reflective film, a protective film and an absorber film were formed in that order in the same manner as in Example 1 to obtain a reflective mask blank.
Next, using this reflective mask blank, a reflective mask of Example 4 was produced in the same manner as in Example 1.

The reflective mask of Example 4 thus obtained was set on a movable stage by an electrostatic chuck in an exposure device, and a pattern was transferred onto a semiconductor substrate on which a resist film had been formed.

Example 5
A TaN conductive film made of tantalum and nitrogen was formed on the back surface of a substrate prepared in the same manner as in Example 1. The substrate was placed in a sputtering device, and a tantalum (Ta) target was used, and a mixed gas of argon (Ar) and nitrogen ( _N2 ) (flow ratio (%) Ar: _N2 = 60:40) was used as the sputtering gas, to form a TaN film (composition ratio Ta:N = 73 atomic %: 27 atomic %) with a thickness of 70 nm by reactive sputtering.

For the TaN conductive film formed, the crystallite size of the conductive film was 4.8 nm, calculated from the diffraction angle 2θmax at which the diffraction intensity obtained by 2θ/ω measurement using X-ray diffraction was maximum in the diffraction angle 2θ range of 30 degrees to 90 degrees.

The substrate with the conductive film obtained in the above manner was subjected to 100 repeated attachment and detachment to the electrostatic chuck in the same manner as in Example 1, and then the conductive film was inspected for defects of 1.0 μm or more using a defect inspection device.

Next, on the surface of another substrate with a conductive film prepared in exactly the same manner as above, opposite the conductive film, a multilayer reflective film, a protective film and an absorber film were formed in that order in the same manner as in Example 1 to obtain a reflective mask blank.
Next, using this reflective mask blank, a reflective mask of Example 5 was produced in the same manner as in Example 1.

The reflective mask of Example 5 thus obtained was set on a movable stage by an electrostatic chuck in an exposure device, and a pattern was transferred onto a semiconductor substrate on which a resist film had been formed.

Example 6
A TaN conductive film made of tantalum and nitrogen was formed on the back surface of a substrate prepared in the same manner as in Example 1. The substrate was placed in a sputtering device, and a tantalum (Ta) target was used, and a mixed gas of argon (Ar) and nitrogen ( _N2 ) (flow ratio (%) Ar: _N2 = 53:47) was used as the sputtering gas, to form a TaN film (composition ratio Ta:N = 64 atomic %: 36 atomic %) with a thickness of 70 nm by reactive sputtering.

For the TaN conductive film formed, the crystallite size of the conductive film was 5.5 nm, calculated from the diffraction angle 2θmax at which the diffraction intensity obtained by 2θ/ω measurement using X-ray diffraction was maximum in the diffraction angle 2θ range of 30 degrees to 90 degrees.

The substrate with the conductive film obtained in the above manner was subjected to 100 repeated attachment and detachment to the electrostatic chuck in the same manner as in Example 1, and then the conductive film was inspected for defects of 1.0 μm or more using a defect inspection device.

Next, on the surface of another substrate with a conductive film prepared in exactly the same manner as above, opposite the conductive film, a multilayer reflective film, a protective film and an absorber film were formed in that order in the same manner as in Example 1 to obtain a reflective mask blank.
Next, using this reflective mask blank, a reflective mask of Example 6 was produced in the same manner as in Example 1.

The reflective mask of Example 6 thus obtained was set on a movable stage by an electrostatic chuck in an exposure device, and a pattern was transferred onto a semiconductor substrate on which a resist film had been formed.

(Example 7)
A TaN conductive film made of tantalum and nitrogen was formed on the back surface of a substrate prepared in the same manner as in Example 1. The substrate was placed in a sputtering device, and a tantalum (Ta) target was used, and a mixed gas of xenon (Xe) and nitrogen ( _N2 ) (flow ratio (%) Xe: _N2 = 52:48) was used as the sputtering gas, to form a TaN film (composition ratio Ta:N = 75 atomic %: 25 atomic %) with a thickness of 70 nm by reactive sputtering.

For the TaN conductive film formed, the crystallite size of the conductive film was 5.6 nm, calculated from the diffraction angle 2θmax at which the diffraction intensity obtained by 2θ/ω measurement using X-ray diffraction was maximum in the diffraction angle 2θ range of 30 degrees to 90 degrees.

The substrate with the conductive film obtained in the above manner was subjected to 100 repeated attachment and detachment to the electrostatic chuck in the same manner as in Example 1, and then the conductive film was inspected for defects of 1.0 μm or more using a defect inspection device.

Next, on the surface of another substrate with a conductive film prepared in exactly the same manner as above, opposite the conductive film, a multilayer reflective film, a protective film and an absorber film were formed in that order in the same manner as in Example 1 to obtain a reflective mask blank.
Next, using this reflective mask blank, a reflective mask of Example 7 was produced in the same manner as in Example 1.

The reflective mask of Example 7 thus obtained was set on a movable stage by an electrostatic chuck in an exposure device, and a pattern was transferred onto a semiconductor substrate on which a resist film had been formed.

(Example 8)
A CrON conductive film made of chromium, oxygen and nitrogen was formed on the back surface of a substrate prepared in the same manner as in Example 1. The substrate was placed in a sputtering device, and a chromium (Cr) target was used. A mixed gas of argon (Ar), oxygen ( _O2 ) and nitrogen ( _N2 ) (flow ratio (%) Ar: _O2 : _N2 = 50:29:21) was used as the sputtering gas, and a CrON film (composition ratio Cr:O:N = 75 atomic %:15 atomic %:10 atomic %) with a thickness of 70 nm was formed by reactive sputtering.

For the CrON conductive film formed, the crystallite size of the conductive film was 4.6 nm, calculated from the diffraction angle 2θmax at which the diffraction intensity obtained by 2θ/ω measurement using X-ray diffraction was maximum in the diffraction angle 2θ range of 30 degrees to 90 degrees.

The substrate with the conductive film obtained in the above manner was subjected to 100 repeated attachment and detachment to the electrostatic chuck in the same manner as in Example 1, and then the conductive film was inspected for defects of 1.0 μm or more using a defect inspection device.

Next, on the surface of another substrate with a conductive film prepared in exactly the same manner as above, opposite the conductive film, a multilayer reflective film, a protective film and an absorber film were successively formed in the same manner as in Example 1 to obtain a reflective mask blank.
Next, using this reflective mask blank, a reflective mask of Example 8 was produced in the same manner as in Example 1.

The reflective mask of Example 8 thus obtained was set on a movable stage by an electrostatic chuck in an exposure device, and a pattern was transferred onto a semiconductor substrate on which a resist film had been formed.

(Comparative Example 1)
A TaN conductive film made of tantalum and nitrogen was formed on the back surface of a substrate prepared in the same manner as in Example 1. The substrate was placed in a sputtering device, and a tantalum (Ta) target was used, and a mixed gas of argon (Ar) and nitrogen ( _N2 ) (flow ratio (%) Ar: _N2 = 65:35) was used as the sputtering gas, to form a TaN film (composition ratio Ta:N = 75 atomic %: 25 atomic %) with a thickness of 70 nm by reactive sputtering.

For the TaN conductive film formed, the crystallite size of the conductive film was 2.0 nm, calculated from the diffraction angle 2θmax at which the diffraction intensity obtained by 2θ/ω measurement using X-ray diffraction was maximum in the diffraction angle 2θ range of 30 degrees to 90 degrees.

The substrate with the conductive film obtained in the above manner was subjected to 100 repeated attachment and detachment to the electrostatic chuck in the same manner as in Example 1, and then the conductive film was inspected for defects of 1.0 μm or more using a defect inspection device.

Next, on the surface of another substrate with a conductive film prepared in exactly the same manner as above, opposite the conductive film, a multilayer reflective film, a protective film and an absorber film were formed in that order in the same manner as in Example 1 to obtain a reflective mask blank.
Next, using this reflective mask blank, a reflective mask of Comparative Example 1 was produced in the same manner as in Example 1.

The reflective mask of Comparative Example 1 thus obtained was set on a movable stage by an electrostatic chuck in the exposure device, and a pattern was transferred onto a semiconductor substrate on which a resist film had been formed.

(Comparative Example 2)
A TaN conductive film made of tantalum and nitrogen was formed on the back surface of a substrate prepared in the same manner as in Example 1. The substrate was placed in a sputtering device, and a tantalum (Ta) target was used, and a mixed gas of argon (Ar) and nitrogen ( _N2 ) (flow ratio (%) Ar: _N2 = 72:28) was used as the sputtering gas, to form a TaN film (composition ratio Ta:N = 81 atomic %: 19 atomic %) with a thickness of 70 nm by reactive sputtering.

For the TaN conductive film formed, the crystallite size of the conductive film was 1.8 nm, calculated from the diffraction angle 2θmax at which the diffraction intensity obtained by 2θ/ω measurement using X-ray diffraction was maximum in the diffraction angle 2θ range of 30 degrees to 90 degrees.

The substrate with the conductive film obtained in the above manner was subjected to 100 repeated attachment and detachment to the electrostatic chuck in the same manner as in Example 1, and then the conductive film was inspected for defects of 1.0 μm or more using a defect inspection device.

Next, on the surface of another substrate with a conductive film prepared in exactly the same manner as above, opposite the conductive film, a multilayer reflective film, a protective film and an absorber film were formed in that order in the same manner as in Example 1 to obtain a reflective mask blank.
Next, using this reflective mask blank, a reflective mask of Comparative Example 2 was produced in the same manner as in Example 1.

The reflective mask of Comparative Example 2 thus obtained was set on a movable stage by an electrostatic chuck in the exposure device, and a pattern was transferred onto a semiconductor substrate on which a resist film had been formed.

As described above, in Examples 1 to 8 and Comparative Examples 1 and 2, the conductive film-attached substrates were repeatedly attached to and detached from the electrostatic chuck 100 times, and then the conductive film was inspected for defects of 1.0 μm or more using a defect inspection device. As a result, in each of the conductive film-attached substrates of Examples 1 to 8, the number of defects of 1.0 μm or more was less than three, which was negligible. In other words, the generation of particles was suppressed. Note that the number of defects is the number of defects per conductive film-attached substrate (one conductive film). The same applies to the comparative examples.
On the other hand, in each of the substrates with conductive film in Comparative Examples 1 and 2, the number of defects of 1.0 μm or more was large, at 100 or more, and there was a large amount of particle generation.

Furthermore, as described above, when the reflective masks of Examples 1 to 8 were used to transfer a pattern onto a semiconductor substrate, high-precision pattern transfer was achieved without causing positional deviation even when the moving speed of the stage carrying the reflective mask was increased.
On the other hand, when a pattern was transferred onto a semiconductor substrate using each of the reflective masks of Comparative Examples 1 and 2, positional deviation occurred when the movement speed of the stage carrying the reflective mask was increased, and high-precision pattern transfer was not possible.

As is apparent from the embodiments described above, the substrate with a conductive film of the present invention can be firmly attached to an electrostatic chuck and easily detached from the electrostatic chuck, thereby making it possible to suppress the generation of particles due to attachment and detachment to the electrostatic chuck.
Furthermore, by performing pattern transfer by exposure using a reflective mask to which the conductive film-formed substrate of the present invention is applied, highly accurate pattern transfer can be performed, and high-quality semiconductor devices with few defects can be manufactured.

Reference Signs List 1 Substrate 2 Conductive film 3 Multilayer reflective film 4 Protective film 5 Absorber film 6 Etching mask film 10 Substrate with conductive film 20 Substrate with multilayer reflective film 30, 40, 50 Reflective mask blank 60 Reflective mask

Claims (11)

A substrate having a conductive film provided on a first main surface of the substrate,
A substrate with a conductive film, characterized in that the crystallite size of the conductive film is 2.5 nm or more, calculated from the diffraction angle 2θmax at which the diffraction intensity obtained by 2θ/ω measurement using X-ray diffraction is maximum in the diffraction angle 2θ range of 30 degrees or more and 90 degrees or less. The conductive film-attached substrate according to claim 1, characterized in that the conductive film contains tantalum or chromium. The conductive film-attached substrate according to claim 1 or 2, characterized in that the conductive film contains 95 atomic % or more of tantalum. The conductive film-attached substrate according to claim 1 or 2, characterized in that the conductive film contains tantalum and nitrogen in total at 95 atomic % or more. The conductive film-attached substrate according to claim 1 or 2, characterized in that the conductive film is formed in contact with the substrate. The conductive film-attached substrate according to claim 1 or 2, characterized in that the conductive film has compressive stress. A substrate with a multilayer reflective film, characterized in that a multilayer reflective film is formed on a second main surface facing the first main surface of the conductive film-coated substrate according to claim 1 or 2, the multilayer reflective film being formed by alternately stacking high refractive index layers and low refractive index layers. A reflective mask blank comprising an absorber film formed on the multilayer reflective film of the multilayer reflective film-coated substrate according to claim 7. The reflective mask blank according to claim 8, characterized in that a protective film is formed between the multilayer reflective film and the absorber film. A reflective mask having an absorber film pattern obtained by patterning the absorber film of the reflective mask blank according to claim 8 by etching. 11. A method for manufacturing a semiconductor device, comprising the step of transferring the absorber film pattern onto a transfer target by exposure using the reflective mask according to claim 10.

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