JP2012049498A - Reflective mask blank for euv lithography, substrate with functional film for mask blank - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a substrate with a conductive film for EUV mask blank in which reflection light in a vacuum ultraviolet region from a back conductive film can be minimized.SOLUTION: The substrate with a conductive film, where a conductive film is formed on a glass substrate, is used for production of a reflective mask blank for EUV lithography, and an intermediate film is provided between the glass substrate and the conductive film. The intermediate film has a refractive index (n) in the range of 1.47-3.00 for the wavelength of 190-400 nm, and an extinction coefficient (k) in the range of 0-1.0, and total thickness of the intermediate film and the conductive film is 50-200 nm.

Description

  The present invention is a reflective mask blank (hereinafter referred to as “EUV mask blank”) for EUV (Extreme Ultraviolet) lithography used for semiconductor manufacturing and the like, and used for manufacturing the mask blank. The present invention relates to a substrate with a conductive film.

  2. Description of the Related Art Conventionally, in the semiconductor industry, a photolithography method using visible light or ultraviolet light has been used as a technique for transferring a fine pattern necessary for forming an integrated circuit having a fine pattern on a silicon substrate or the like. However, while miniaturization of semiconductor devices is accelerating, the limits of conventional photolithography methods have been approached. In the case of the photolithography method, the resolution limit of the pattern is about ½ of the exposure wavelength, and it is said that the immersion wavelength is about ¼ of the exposure wavelength, and the immersion of ArF laser (193 nm) is used. Even if the method is used, the limit of about 45 nm is expected. Therefore, EUV lithography, which is an exposure technique using EUV light having a wavelength shorter than that of an ArF laser, is promising as an exposure technique for 45 nm and beyond. In this specification, EUV light refers to light having a wavelength in the soft X-ray region or vacuum ultraviolet region, and specifically refers to light having a wavelength of about 10 to 20 nm, particularly about 13.5 nm ± 0.3 nm.

  Since EUV light is easily absorbed by any material and the refractive index of the material is close to 1 at this wavelength, a conventional refractive optical system such as photolithography using visible light or ultraviolet light may be used. Can not. For this reason, in the EUV light lithography, a reflective optical system, that is, a reflective photomask and a mirror are used.

The mask blank is a laminated body before patterning used for photomask manufacturing. The EUV mask blank has a structure in which a reflective layer that reflects EUV light and an absorption layer that absorbs EUV light are formed in this order on a glass substrate or the like. As the reflective layer, a molybdenum (Mo) layer, which is a high refractive layer, and a silicon (Si) layer, which is a low refractive layer, are alternately laminated, thereby increasing the light reflectance when EUV light is irradiated on the surface of the layer. The produced Mo / Si multilayer reflective film is usually used.
For the absorption layer, a material having a high absorption coefficient for EUV light, specifically, a material mainly composed of, for example, chromium (Cr) or tantalum (Ta) is used.

  The multilayer reflective film and the absorption layer are formed on the optical surface of the glass substrate using an ion beam sputtering method or a magnetron sputtering method. When forming the multilayer reflective film and the absorbing layer, the glass substrate is held by the support means. There are mechanical chucks and electrostatic chucks as means for supporting the glass substrate, but electrostatic chucks are preferably used from the viewpoint of dust generation. An electrostatic chuck is also used as a supporting means for the glass substrate during the mask patterning process or during mask handling during exposure.

The electrostatic chuck is a technique conventionally used as a means for supporting a silicon wafer in a semiconductor device manufacturing process. For this reason, in the case of a substrate having a low dielectric constant and conductivity, such as a glass substrate, it is necessary to apply a high voltage in order to obtain a chucking force equivalent to that in the case of a silicon wafer. There is sex.
In order to solve such a problem, Patent Document 1 discloses a material other than ordinary Cr, such as Si, Mo, chromium oxynitride (CrON), or TaSi, as a layer for promoting electrostatic chucking of the substrate. Further, a mask substrate having a back coating (back conductive film) of a substance having a higher dielectric constant and higher conductivity than a glass substrate is described.

  In recent years, in the mask blank for a reflective photomask, as the pattern becomes finer, the influence of shadowing (deterioration of pattern accuracy) due to the thickness of the absorption layer has become a problem, and absorption is performed to suppress the influence of this shadowing. Thinning of the layer has been studied. This is a technique for achieving thinning of the absorbing layer by utilizing the phase effect of the EUV reflected light between the reflecting layer surface and the absorbing layer surface. That is, the EUV reflected light on the surface of the absorbing layer increases by making the absorbing layer thin, but it is sufficient on the Si wafer by shifting the phase of the reflected light on the absorbing layer surface and the reflected light on the reflecting layer surface by 180 degrees. Pattern contrast can be obtained. However, in the pattern formation region, the absorption layer can be thinned by using the above phase effect. However, since sufficient phase effect cannot be obtained in the non-pattern formation region (periphery of the exposure region), EUV lithography is performed. When it is carried out, there arises a problem that unnecessary resist on the Si wafer is exposed. As a technique for solving this, there is a technique of removing the absorption layer and the reflection layer on the outer peripheral portion of the exposure region by etching (Patent Document 2). According to this technique, since the glass surface is exposed at the outer peripheral portion of the exposure region, EUV light is not reflected, and unnecessary resist exposure on the Si wafer can be prevented.

Japanese translation of PCT publication No. 2003-501823 JP 2002-217097 A

  However, the light source used for EUV exposure includes not only EUV wavelength (about 10 to 20 nm) but also light in the vacuum ultraviolet region (wavelength 190 to 400 nm). When the absorption layer and the reflection layer are etched to expose the glass surface, the light in the vacuum ultraviolet region transmitted through the glass substrate is reflected by the back surface conductive film to generate reflected light, and this reflected light is unnecessary on the Si wafer. Resist is exposed to light, resulting in a problem that pattern accuracy deteriorates. In order to prevent such a problem, the reflectance in the vacuum ultraviolet region (wavelength 190 to 400 nm) is required to be 10% or less.

In order to solve the above-described problems of the prior art, an object of the present invention is to provide a conductive film-coated substrate for EUV mask blanks that can suppress the reflected light in the vacuum ultraviolet region from the back surface conductive film. .
Moreover, an object of this invention is to provide the board | substrate with a multilayer reflective film of the EUV mask blank using the board | substrate with this electrically conductive film, and an EUV mask blank.

The present inventor suppresses the reflection in the vacuum ultraviolet region (190 to 400 nm) from the back surface conductive film side by providing an intermediate film satisfying specific optical conditions between the glass substrate and the conductive film. It has been found that the reflectance of the region (190 to 400 nm) can be made 10% or less.

  The present invention has been made based on the above knowledge, and is a substrate with a conductive film used for manufacturing a reflective mask blank for EUV lithography in which a conductive film is formed on a glass substrate, the glass An intermediate film is provided between the substrate and the conductive film. The intermediate film has a refractive index (n) in the range of 1.47 to 3.00 with respect to a wavelength of 190 nm to 400 nm, and an extinction coefficient (k). Is in the range of 0 to 1.0, and the total film thickness of the intermediate film and the conductive film is 50 to 200 nm.

  In the substrate with a conductive film of the present invention, the intermediate film contains at least one selected from the group consisting of chromium (Cr) and tantalum (Ta) and oxygen (O), and contains chromium (Cr) and tantalum ( The total content of Ta) is preferably 10 to 90 at%, and the content of oxygen (O) is preferably 10 to 90 at%.

  In the substrate with a conductive film of the present invention, the intermediate film contains at least one selected from the group consisting of chromium (Cr) and tantalum (Ta), oxygen (O) and nitrogen (N), and chromium ( The total content of Cr) and tantalum (Ta) is 10 to 80 at%, the total content of oxygen (O) and nitrogen (N) is 20 to 90 at%, and the composition ratio of O and N is O: It is preferable that N = 9: 1 to 5: 5.

  In the substrate with a conductive film of the present invention, the conductive film contains at least one selected from the group consisting of chromium (Cr) and tantalum (Ta) and nitrogen (N), and includes chromium (Cr) and tantalum. The total content of (Ta) is preferably 60 at% or more and less than 99.9 at%, and the content of nitrogen (N) is preferably 0.1 at% or more and less than 40 at%.

  In the substrate with a conductive film of the present invention, the total thickness of the intermediate film and the conductive film is preferably 50 to 195 nm, more preferably 50 to 190 nm, and further preferably 50 to 100 nm. Preferably, it is 50 to 95 nm, more preferably 50 to 90 nm.

  In the substrate with a conductive film of the present invention, the sheet resistance value of the intermediate film and the conductive film is preferably 0.1 to 100 Ω / □.

  Further, the present invention provides a substrate with a multilayer reflective film for a reflective mask blank for EUV lithography, wherein a multilayer reflective film is formed on the opposite side of the surface with the conductive film of the substrate with a conductive film of the present invention. I will provide a.

  The present invention also provides a reflective mask blank for EUV lithography in which an absorption layer is formed on the multilayer reflective film of the substrate with the multilayer reflective film of the present invention.

  The present invention also provides a reflective mask for EUV lithography obtained by patterning the reflective mask blank for EUV lithography of the present invention.

According to the substrate with a conductive film of the present invention, the reflection in the vacuum ultraviolet region (190 to 400 nm) from the back conductive film side is suppressed, and the reflectance in the vacuum ultraviolet region (wavelength 190 to 400 nm) is made 10% or less. Can do.
For this reason, in the EUV mask created using the substrate with a conductive film of the present invention, when the absorption layer and the reflective layer in the outer peripheral portion of the exposure region are etched to expose the glass substrate, the exposure from the outer peripheral portion of the exposure region The reflected light in the vacuum ultraviolet region suppresses unnecessary resist on the Si wafer from being exposed, and the pattern accuracy is improved.

FIG. 1 is a schematic view of a substrate with a conductive film of the present invention. FIG. 2 is a graph showing the reflectance at a wavelength of 400 nm when the thickness and extinction coefficient of the intermediate film 3 are used as parameters when the refractive index n of the intermediate film 3 is 1.47. FIG. 3 is a graph showing the reflectance at a wavelength of 400 nm when the refractive index n of the intermediate film 3 is 3.00 and the film thickness and extinction coefficient of the intermediate film 3 are used as parameters. FIG. 4 is a schematic view of a substrate with a multilayer reflective film of the present invention. FIG. 5 is a schematic view of the EUV mask blank of the present invention.

The present invention will be described below with reference to the drawings. FIG. 1 is a schematic view of a substrate with a conductive film of the present invention. In FIG. 1, a conductive film 2 is formed on one surface side of a glass substrate 1 for film formation. When forming the multilayer reflective film and the absorbing layer on the substrate 1, the glass substrate 1 is fixed to the electrostatic chuck via the conductive film 2. As will be described later, the multilayer reflection film and the absorption layer are formed on the opposite side (film formation surface) of the surface of the glass substrate 1 on which the conductive film 2 is formed. In short, the conductive film 2 is a back conductive film formed on the back side with respect to the film formation surface of the glass substrate 1.
In the substrate with a conductive film of the present invention, an intermediate film 3 satisfying the optical characteristics described below is formed between the glass substrate 1 and the conductive film 2, so that a vacuum ultraviolet region (190 to 400 nm) from the conductive film 2 is formed. ) And the reflectance in the vacuum ultraviolet region (190 to 400 nm) is 10% or less. The reflected light from the conductive film 2 referred to here does not occur when light incident on the surface of the conductive film 2 from the lower side in the figure is reflected by the surface of the conductive film 2, but from the upper side in the figure. The light that has passed through is reflected by the interface between the substrate 1 and the conductive film 2.

When the refractive indexes of the glass substrate 1, the intermediate film 3 and the conductive film 2 with respect to light in the vacuum ultraviolet region (190 to 400 nm) are N ₁ , N ₃ and N ₂ , respectively, the surface of the intermediate film 3 (the glass substrate 1 and the intermediate film) reflectivity R ₂ of the reflectivity R ₃ and the conductive film 2 surface (the interface with the intermediate layer 3 and the conductive film 2) of the 3 interface with) are respectively expressed as follows.
(Formula _{1) R 3 = (N 1} -N 3) / (N 1 + N 3)
(Formula 2) R ₂ = (N ₃ −N ₂ ) / (N ₃ + N ₂ )
Here, when R ₃ and R ₂ are equal, low reflection characteristics can be obtained for light in the vacuum ultraviolet region (190 to 400 nm). The optimum refractive index N ₃ of the intermediate film 3 at this time is expressed by the following (formula 3).
(Formula 3) N ₃ = (N ₁ N ₂ ) ^1/2

In the glass substrate 1 of the EUV mask blank, silica glass (SiO ₂ —TiO ₂ glass) containing TiO ₂ as a dopant has a lower coefficient of linear thermal expansion (Coefficient of Thermal Expansion; CTE) than that of quartz glass. It is known as a material, and is preferably used because a zero-expansion glass having a linear thermal expansion coefficient close to 0 can be obtained by controlling the linear thermal expansion coefficient according to the TiO ₂ content in the glass. The refractive index (N ₁ ) for light in the vacuum ultraviolet region (190 to 400 nm) of the SiO ₂ —TiO ₂ glass substrate is included in the range of 1.45 to 1.65.
On the other hand, since the back surface conductive film of the EUV mask blank is required to have a higher dielectric constant and conductivity than the glass substrate, metallic films such as Cr, Ta, Si, Ti, and nitrides thereof (for example, CrN film) is used. The refractive index (N ₂ ) for light in the vacuum ultraviolet region (190 to 400 nm) of these metallic films is included in the range of 1.5 to 5.5.
From the above range of N ₁ and N ₂ and (Equation 3), the refractive index (N ₃ ) of the intermediate film 3 is preferably 1.47 to 3.00.

Further, the intermediate film 3 that is optimal for obtaining the above-described low reflection characteristics with respect to light in the vacuum ultraviolet region (190 to 400 nm), that is, for making the reflectance in the vacuum ultraviolet region (190 to 400 nm) 10% or less. The film thickness is calculated from (Equation 4).
(Formula 4) 2N ₃ d ₃ = λ / 2
Here, d ₃ represents the film thickness of the intermediate film 3.
Assuming that the intermediate film 3 does not absorb light, the film thickness d ₃ of the intermediate film 3 can be selected in the range of 15 nm to 70 nm.
However, in reality, absorption of light in the intermediate film 3 is unavoidable, and therefore the extinction coefficient (k ₃ ) of the intermediate film 3 needs to be considered.
Here, when the extinction coefficient (k ₃ ) of the intermediate film 3 is large, sufficient low reflection characteristics cannot be obtained for light in the vacuum ultraviolet region (190 to 400 nm). k ₃ ) is preferably in the range of 0 to 1.0. The reason is as follows.

2 and 3 show the film thickness (15 of the intermediate film 3 when the glass substrate 1 is a SiO ₂ —TiO ₂ glass substrate (thickness 6.35 mm) and the back conductive film 2 is a CrN film (thickness 50 nm). ˜75 nm) and extinction coefficient (k ₃ ) as parameters, the reflectance at a wavelength of 400 nm is shown. In addition, the reflectance here is a reflectance when a light beam is incident on the upper side of FIG. 1, that is, from the film formation surface side of the glass substrate 1. Moreover, the film thickness of the glass substrate 1 and the back surface conductive film 2 described above is a general film thickness in an EUV mask blank.
FIG. 2 shows the reflectance when the refractive index (N ₃ ) of the intermediate film 3 is set to the lower limit (1.47) of the preferred range (1.47 to 3.00), and FIG. 3 shows the refractive index of the intermediate film 3. It is a reflectance when (N ₃ ) is the upper limit (3.00) of the above-described preferred range (1.47 to 3.00). As is apparent from the figure, when the refractive index (N ₃ ) of the intermediate film 3 is large (FIG. 3), the film thickness of the intermediate film 3 with a reflectance of 10% or less even when k ₃ = 1.1 is However, when the refractive index (N ₃ ) of the intermediate film 3 is small (FIG. 2), there is no film thickness of the intermediate film 3 that gives a reflectance of 10% or less when k ₃ = 1.1. On the other hand, if k ₃ ≦ 1.0, when the refractive index (N ₃ ) of the intermediate film 3 is small (FIG. 2), the film thickness of the intermediate film 3 having a reflectance of 10% or less exists. That is, if k ₃ ≦ 1.0, the refractive index (N ₃ ) of the intermediate film 3 is in the above-described preferable range (1.47 to 3.00), and the reflectance of the intermediate film 3 is set to 10% or less. There is a film thickness. In other words, if k ₃ ≦ 1.0, the film thickness of the intermediate film 3 when the refractive index (N ₃ ) of the intermediate film 3 is in the preferred range (1.47 to 3.00) described above. By adjusting the reflectance, the reflectance can be made 10% or less. Since the lower limit of the extinction coefficient is 0, the above “k ₃ ≦ 1.0” means 0 ≦ k ₃ ≦ 1.0.

This relationship is the same when the wavelength is changed in the vacuum ultraviolet region (190 to 400 nm). If 0 ≦ k ₃ ≦ 1.0, any wavelength in the vacuum ultraviolet region (190 to 400 nm) is obtained. On the other hand, when the refractive index (N ₃ ) of the intermediate film 3 is in the preferred range (1.47 to 3.00), there is a film thickness of the intermediate film 3 with a reflectance of 10% or less.
In order to obtain sufficient conductivity as the back conductive film, the conductive film 2 needs to have a film thickness of 40 nm or more, and the wavelength of 190 to 400 nm of the above-described metallic film used as the back conductive film. Since the extinction coefficient is sufficiently large, the reflection from the back surface (lower surface in the figure) of the conductive film 2 is sufficiently small.
Therefore, it is not necessary to consider the extinction coefficient of the conductive film 2 in order to obtain a sufficiently low reflection characteristic for light in the vacuum ultraviolet region (190 to 400 nm).

In addition to the refractive index (N ₃ ) and extinction coefficient (k ₃ ) satisfying the above ranges, the intermediate film 3 is less prone to film peeling from the substrate 1 and is effective in suppressing the occurrence of defects. From the viewpoint of the target, it is required that the adhesiveness with the glass substrate is good.

Examples of the intermediate film 3 satisfying the above include at least one selected from the group consisting of chromium (Cr) and tantalum (Ta) and an intermediate film (Cr, Ta: O) containing oxygen (O). Specific examples of such an intermediate film (Cr, Ta: O) include a CrO film, a TaO film, and a CrTaO film.
In the intermediate film (Cr, Ta: O), the total content of chromium (Cr) and tantalum (Ta) is 10 to 90 at%, and the content of oxygen (O) is 10 to 90 at%.
If the total content of Cr and Ta in the intermediate film (Cr, Ta: O) is less than 10 at%, the discharge becomes unstable during sputter film formation and abnormal discharge occurs, so that stable film formation becomes difficult. There's a problem.
When the total content of Cr and Ta in the interlayer film (Cr, Ta: O) is more than 90 at%, the above optical conditions (refractive index (N ₃ ), extinction coefficient (k ₃ )) cannot be satisfied. In particular, there is a problem that the absorption coefficient (k ₃ ) is larger than 1.0.
If the O content in the interlayer film (Cr, Ta: O) is less than 10 at%, the above optical conditions (refractive index (N ₃ ), extinction coefficient (k ₃ )) cannot be satisfied. There is a problem that (k ₃ ) becomes larger than 1.0.
If the O content in the intermediate film (Cr, Ta: O) exceeds 90 at%, the discharge becomes unstable during sputtering film formation and abnormal discharge occurs, which makes it difficult to form a stable film. .
The intermediate film (Cr, Ta: O) preferably has a total content of Cr and Ta of 10 to 85 at%, more preferably 15 to 85 at%, and still more preferably 15 to 80 at%. .
The intermediate film (Cr, Ta: O) preferably has an O content of 15 to 90 at%, more preferably 15 to 85 at%, and still more preferably 20 to 85 at%.

The intermediate film (Cr, Ta: O) may contain elements other than O and at least one selected from the group consisting of Cr and Ta as necessary. In this case, the element included in the intermediate film must satisfy the characteristics required for the intermediate film 3 described above.
An example of an element that can be included in the intermediate film (Cr, Ta: O) is nitrogen (N). It is considered that the smoothness of the surface of the intermediate film is improved when the intermediate film contains N. When the smoothness of the intermediate film surface is improved, it is expected that the smoothness of the surface of the conductive film formed on the intermediate film is also improved.
Specific examples of such an intermediate film (Cr, Ta: ON) include a CrON film, a TaON film, and a CrTaON film.

The intermediate film (Cr, Ta: ON) has a total content of Cr and Ta of 20 to 80 at%, a total content of O and N of 20 to 80 at%, and a composition ratio of O and N of 9: It is preferably 1 to 5: 5.
If the total content of Cr and Ta in the intermediate film (Cr, Ta: ON) is less than 20 at%, the discharge becomes unstable at the time of sputtering film formation, and abnormal discharge occurs, so that stable film formation becomes difficult. There is a problem.
When the total content of Cr and Ta in the intermediate film (Cr, Ta: ON) is more than 80 at%, the above optical conditions (refractive index (N ₃ ), extinction coefficient (k ₃ )) cannot be satisfied. In particular, there is a problem that the absorption coefficient (k ₃ ) is larger than 1.0.
If the O and N content in the intermediate film (Cr, Ta: ON) is less than 20 at%, the above optical conditions (refractive index (N ₃ ), extinction coefficient (k ₃ )) cannot be satisfied. There is a problem that the absorption coefficient (k ₃ ) is larger than 1.0.
If the O and N content in the intermediate film (Cr, Ta: ON) exceeds 80 at%, the discharge becomes unstable during sputter deposition and abnormal discharge occurs, making it difficult to achieve stable deposition. There is.
When O of the interlayer film (Cr, Ta: ON) is lower than the above composition ratio, the above optical conditions (refractive index (N ₃ ), extinction coefficient (k ₃ )) cannot be satisfied, especially the absorption coefficient (k There is a problem that ₃ ) becomes larger than 1.0.
When O of the intermediate film (Cr, Ta: ON) is higher than the above composition ratio, there is a problem that the effect of improving the smoothness of the intermediate film surface by adding N cannot be obtained sufficiently.

The intermediate film (Cr, Ta: ON) preferably has a total content of Cr and Ta of 20 to 78 at%, more preferably 22 to 78 at%, and still more preferably 22 to 75 at%. .
The intermediate film (Cr, Ta: ON) preferably has a total content of O and N of 22 to 80 at%, more preferably a total content of Cr and Ta of 22 to 78 at%. More preferably, it is 78 at%.
The intermediate film (Cr, Ta: ON) preferably has a composition ratio of O and N of 8.8: 1.2 to 5.2: 4.8, and 8.5: 1.5 to 5.5. : 4.5 is more preferable, and 8: 2 to 6: 4 is more preferable.

The intermediate film (Cr, Ta: ON) has an amorphous crystal state and a smooth surface. Specifically, the surface roughness (rms) of the surface of the intermediate film (Cr, Ta: ON) is 0.5 nm or less.
As will be described in detail later, excellent smoothness of the surface of the conductive film can prevent generation of particles due to friction between the electrostatic chuck and the conductive film when the substrate with the conductive film is attracted and held by the electrostatic chuck. preferable. When the smoothness of the intermediate film surface is improved, it is expected that the smoothness of the surface of the conductive film formed on the intermediate film is also improved.
If the surface roughness (rms) of the surface of the intermediate film (Cr, Ta: ON) is 0.5 nm or less, the surface of the intermediate film (Cr, Ta: ON) is sufficiently smooth, and thus formed on the intermediate film. The surface roughness (rms) of the surface of the conductive film is expected to be 0.5 nm or less.
The surface roughness (rms) of the intermediate film (Cr, Ta: ON) surface is more preferably 0.4 nm or less, and further preferably 0.3 nm or less.
Note that the crystal state of the intermediate film (Cr, Ta: ON) can be confirmed by an X-ray diffraction (XRD) method to be amorphous, that is, to be an amorphous structure or a microcrystalline structure. . If the crystal state of the intermediate film (Cr, Ta: ON) is an amorphous structure or a microcrystalline structure, a sharp peak is not observed in a diffraction peak obtained by XRD measurement.

The intermediate film 3 has a total film thickness of 50 to 200 nm with the conductive film 2. As described above, in order to obtain sufficient conductivity as the back surface conductive film, the conductive film 2 needs to have a film thickness of 40 nm or more. Therefore, the total film thickness of the conductive film 2 and the intermediate film 3 is less than 50 nm. Then, since the film thickness of the intermediate film 3 becomes too small, reflection in the vacuum ultraviolet region (190 to 400 nm) from the conductive film 2 side cannot be sufficiently suppressed, and in the vacuum ultraviolet region (wavelength 190 to 400 nm). The reflectance cannot be 10% or less.
When the total film thickness of the conductive film 2 and the intermediate film 3 is more than 200 nm, the increase in the film thickness no longer contributes to the improvement of the functions of the conductive film 2 and the intermediate film 3. The time required for the formation increases, and the cost required for forming the conductive film 2 and the intermediate film 3 increases. Moreover, since the total film thickness of the conductive film 2 and the intermediate film 3 becomes larger than necessary, the possibility of film peeling increases.
The total film thickness of the conductive film 2 and the intermediate film 3 is preferably 50 to 195 nm, more preferably 50 to 190 nm, still more preferably 50 to 100 nm, and further preferably 50 to 95 nm. Preferably, it is 50 to 90 nm.
The film thickness of the intermediate film 3 is preferably 10 to 50 nm, more preferably 10 to 45 nm, and further preferably 10 to 40 nm.

The formation procedure of the intermediate film 3 is shown below.
When the intermediate film 3 is a CrO film, oxygen (O ₂₎ diluted with an inert gas containing at least one of helium (He), argon (Ar), neon (Ne), krypton (Kr), and xenon (Xe). ) It is formed by discharging a Cr target in an atmosphere.
When the intermediate film 3 is a TaO film, oxygen (O ₂₎ diluted with an inert gas containing at least one of helium (He), argon (Ar), neon (Ne), krypton (Kr), and xenon (Xe). ) It is formed by discharging a Ta target in an atmosphere.

When the intermediate film 3 is a CrON film, oxygen (O ₂₎ diluted with an inert gas containing at least one of helium (He), argon (Ar), neon (Ne), krypton (Kr), and xenon (Xe). ) And a nitrogen (N ₂ ) atmosphere by performing a sputtering method using a Cr target, for example, a magnetron sputtering method or an ion beam sputtering method. Alternatively, the Cr target is discharged in a nitrogen (N ₂ ) atmosphere diluted with an inert gas containing at least one of helium (He), argon (Ar), neon (Ne), krypton (Kr), and xenon (Xe). Then, after forming the CrN film, the formed film may be oxidized by, for example, exposing it to oxygen plasma or irradiating an ion beam using oxygen, thereby forming a CrON film.
When the intermediate film 3 is a TaON film, oxygen (O ₂₎ diluted with an inert gas containing at least one of helium (He), argon (Ar), neon (Ne), krypton (Kr), and xenon (Xe). ) And a nitrogen (N ₂ ) atmosphere by performing a sputtering method using a Ta target, for example, a magnetron sputtering method or an ion beam sputtering method. Alternatively, the Ta target is discharged in a nitrogen (N ₂ ) atmosphere diluted with an inert gas containing at least one of helium (He), argon (Ar), neon (Ne), krypton (Kr), and xenon (Xe). After forming the TaN film, the TaON film may be formed by oxidizing the formed film by exposing it to oxygen plasma or irradiating an ion beam using oxygen, for example.

In order to form the intermediate film 3 by the above-described method, specifically, it may be carried out under the following film forming conditions.
CrO film, if <br/> sputtering gas to form a TaO film:. A mixed gas of Ar and O ₂ (O ₂ gas concentration 3～80Vol%, preferably 5～60Vol%, more preferably 10～40Vol% Gas pressure ^{1.0 × 10 -1 Pa~50 × 10 -1} Pa, preferably ^{1.0 × 10 -1 Pa~40 × 10 -1} Pa, more preferably 1.0 × 10 ^-1 Pa~30 × 10 ^{- 1} Pa.)
Input power: 30 to 1000 W, preferably 50 to 750 W, more preferably 80 to 500 W
Deposition rate: 0.01 to 60 nm / min, preferably 0.05 to 45 nm / min, more preferably 0.1 to 30 nm / min
CrON film, if <br/> sputtering gas to form a TaON film: mixed gas of Ar and O ₂ and N ₂ (O ₂ gas concentration 5~80vol%, N ₂ gas concentration 5～75Vol%, preferably O ₂ gas concentration 6~70vol%, N ₂ gas concentration 6~35vol%, more preferably O ₂ gas concentration 10 to 30 vol%, N ₂ gas concentration 10 to 30 vol% .Ar gas concentration 5~90vol%, preferably 10～88Vol% , more preferably 20～80Vol%, gas pressure ^{1.0 × 10 -1 Pa~50 × 10 -1} Pa, preferably ^{1.0 × 10 -1 Pa~40 × 10 -1} Pa, more preferably 1. 0 × 10 ⁻¹ Pa to 30 × 10 ⁻¹ Pa.)
Input power: 30 to 1000 W, preferably 50 to 750 W, more preferably 80 to 500 W
Deposition rate: 0.01 to 60 nm / min, preferably 0.05 to 45 nm / min, more preferably 0.1 to 30 nm / min
When an inert gas other than argon is used, the concentration of the inert gas is set to the same concentration range as the Ar gas concentration described above. Further, when a plurality of types of inert gases are used, the total concentration of the inert gases is set to the same concentration range as the Ar gas concentration described above.

The conductive film 2 is preferably a conductive film (Cr, Ta: N) containing at least one selected from the group consisting of Cr and Ta and N. In the conductive film (Cr, Ta: N), the total content of Cr and Ta is 60 at% or more and less than 99.9 at%, and the N content is 0.1 at% or more and less than 40 at%.
In the case of a conductive film (Cr, Ta: N), the sheet resistance value is low, which is 27Ω / □ or less. For this reason, sheet resistance values of the conductive film 2 and the intermediate film 3 described later can be set to 100Ω / □ or less. Moreover, since the crystal state is amorphous, the surface is excellent in smoothness. Specifically, the surface roughness (rms) of the conductive film surface is 0.5 nm or less.
Specific examples of such a conductive film (Cr, Ta: N) include a CrN film, a TaN film, and a CrTaN film.

When the N content in the conductive film (Cr, Ta: N) is less than 0.1 at%, the crystalline state becomes a film having crystallinity, that is, a crystal structure. Therefore, the conductive film (Cr, Ta: N ) Increased surface roughness. As a result, the adhesion with the electrostatic chuck is lowered, and particles are likely to be generated due to friction between the electrostatic chuck and the conductive film (Cr, Ta: N). Further, if the N content in the conductive film (Cr, Ta: N) is less than 0.1 at%, the surface hardness of the conductive film (Cr, Ta: N) is lowered. Particles are generated by rubbing between the film and the conductive film (Cr, Ta: N). Further, when the N content in the conductive film (Cr, Ta: N) is less than 0.1 at%, the chemical durability of the conductive film (Cr, Ta: N) tends to be lowered.
On the other hand, when the N content in the conductive film (Cr, Ta: N) is 40 at% or more, the crystalline state becomes a film having crystallinity, that is, a crystal structure. ) Increased surface roughness. Further, when the average concentration of N in the conductive film (Cr, Ta: N) is 40 at% or more, the sheet resistance of the conductive film (Cr, Ta: N) increases and the chucking force by the electrostatic chuck decreases. Adhesiveness with the electrostatic chuck is lowered, and particles are easily generated due to friction between the electrostatic chuck and the conductive film (Cr, Ta: N).
The N content in the conductive film (Cr, Ta: N) is preferably 10 at% or more and less than 40 at%, and more preferably 15 to 36 at%.
The total content of Cr and Ta in the conductive film (Cr, Ta: N) is preferably 60 to 90 at%, and more preferably 64 to 85 at%.

  The conductive film (Cr, Ta: N) has a low sheet resistance and is 27 Ω / □ or less. Since the sheet resistance of the conductive film (Cr, Ta: N) is low, the chucking force by the electrostatic chuck is increased. As a result, adhesion with the electrostatic chuck is improved, and generation of particles due to rubbing between the electrostatic chuck and the conductive film (Cr, Ta: N) is prevented. The sheet resistance of the conductive film (Cr, Ta: N) is more preferably 25Ω / □ or less, and further preferably 23Ω / □ or less.

The conductive film (Cr, Ta: N) has an amorphous crystal state and a smooth surface. Specifically, the surface roughness (rms) of the surface of the conductive film (Cr, Ta: N) is 0.5 nm or less. When the surface roughness of the conductive film (Cr, Ta: N) is 0.5 nm or less, the adhesion with the electrostatic chuck is improved, and the electrostatic chuck and the conductive film (Cr, Ta: N) are rubbed. Generation of particles is prevented.
The surface roughness of the conductive film (Cr, Ta: N) is more preferably 0.4 nm or less in rms, and further preferably 0.3 nm or less.
Note that the crystalline state of the conductive film (Cr, Ta: N) can be confirmed by an X-ray diffraction (XRD) method to be amorphous, that is, an amorphous structure or a microcrystalline structure. . If the crystalline state of the conductive film (Cr, Ta: N) is an amorphous structure or a microcrystalline structure, a sharp peak is not observed in a diffraction peak obtained by XRD measurement.

The conductive film (Cr, Ta: N) preferably has a surface hardness of 12 GPa or more. If the surface hardness of the conductive film (Cr, Ta: N) is 12 GPa or more, the conductive film (Cr, Ta: N) is excellent in surface hardness, and the substrate with the conductive film is fixed to the electrostatic chuck and the EUV mask. When used in the manufacture of a blank, it is excellent in the effect of preventing particles from being generated by rubbing between the electrostatic chuck and the conductive film. Here, the method for measuring the surface hardness of the conductive film (Cr, Ta: N) is not particularly limited, and a known method, specifically, for example, a Vickers hardness test, a Rockwell hardness test, a Brinell hardness test, A nanoindentation test or the like can be used. Among these, the nanoindentation test is widely used when measuring the surface hardness of a thin film.
The surface hardness of the conductive film (Cr, Ta: N) is more preferably 15 GPa or more.

As described above, in order to obtain sufficient conductivity as the back surface conductive film, the conductive film 2 needs to have a thickness of 40 nm or more.
Moreover, as above-mentioned, the total film thickness of the electrically conductive film 2 and the intermediate film 3 in the board | substrate with an electrically conductive film of this invention is 50-200 nm.
The film thickness of the conductive film 2 is preferably 40 to 190 nm, more preferably 40 to 185 nm, still more preferably 40 to 180 nm, still more preferably 40 to 90 nm, and 40 to 85 nm. It is more preferable that the thickness is 40 to 80 nm.

The procedure for forming the conductive film 2 is shown below.
When the conductive film 2 is a CrN film, the conductive film may be formed by magnetron sputtering using a Cr target as a target and a mixed gas of Ar and N ₂ as a sputtering gas.
In the case where the conductive film 2 is a TaN film, the conductive film may be formed using a magnetron sputtering method with a Ta target as a target and a mixed gas of Ar and N ₂ as a sputtering gas.

In order to form the conductive film 2 by the above-described method, specifically, the following film formation conditions may be used.
When forming a CrN film Target: Cr target Sputtering gas: Mixed gas of Ar and N ₂ (N ₂ gas concentration: 3 to 45 vol%, preferably 5 to 40 vol%, more preferably 10 to 35 vol%. Gas) pressure ^{1.0 × 10 -1 Pa~50 × 10 -1} Pa, preferably ^{1.0 × 10 -1 Pa~40 × 10 -1} Pa, more preferably 1.0 × 10 ^-1 Pa~30 × 10 ^-1 Pa.)
Input power: 30 to 1000 W, preferably 50 to 750 W, more preferably 80 to 500 W
Deposition rate: 2.0-60 nm / min, preferably 3.5-45 nm / min, more preferably 5-30 nm / min
When forming a TaN film Target: Ta target sputtering gas: Ar and N ₂ mixed gas (N ₂ gas concentration: 3 to 45 vol%, preferably 5 to 40 vol%, more preferably 10 to 35 vol%. Gas) pressure ^{1.0 × 10 -1 Pa~50 × 10 -1} Pa, preferably ^{1.0 × 10 -1 Pa~40 × 10 -1} Pa, more preferably 1.0 × 10 ^-1 Pa~30 × 10 ^-1 Pa.)
Input power: 30 to 1000 W, preferably 50 to 750 W, more preferably 80 to 500 W
Deposition rate: 2.0-60 nm / min, preferably 3.5-45 nm / min, more preferably 5-30 nm / min

In the substrate with a conductive film of the present invention, the glass substrate 1 for film formation is required to satisfy the characteristics as a glass substrate for EUV mask blank.
Therefore, the glass substrate 1 preferably has a low coefficient of thermal expansion (0 ± 1.0 × 10 ⁻⁷ / ° C., more preferably 0 ± 0.3 × 10 ⁻⁷ / ° C., and further preferably 0 ± 0. 2 × 10 ⁻⁷ / ° C., more preferably 0 ± 0.1 × 10 ⁻⁷ / ° C., particularly preferably 0 ± 0.05 × 10 ⁻⁷ / ° C.), smoothness, flatness, and mask A material excellent in resistance to a cleaning solution used for cleaning a blank or a photomask after pattern formation is preferable. Specifically, glass having a low thermal expansion coefficient, for example, SiO ₂ —TiO ₂ glass, or the like can be used as the glass substrate 1.
The glass substrate 1 preferably has a smooth surface of 0.15 nm rms or less and a flatness of 100 nm or less in order to obtain high reflectance and transfer accuracy in a photomask after pattern formation.
The size, thickness, etc. of the glass substrate 1 are appropriately determined according to the design value of the mask. In the examples described later, SiO ₂ —TiO ₂ glass having an outer shape of 6 inches (152.4 mm) square and a thickness of 0.25 inches (6.3 mm) was used.

Next, the substrate with a multilayer reflective film of the present invention will be described. FIG. 4 is a schematic view of a substrate with a multilayer reflective film of the present invention. In FIG. 4, a multilayer reflective film 4 is formed on the opposite side of the surface of the glass substrate 1 on which the intermediate film 3 and the conductive film 2 are formed. Here, the glass substrate 1, the intermediate film 3, and the conductive film 2 are those shown in FIG. 1 (the substrate with the conductive film of the present invention). The substrate with a multilayer reflective film of the present invention is formed on the film formation surface of the glass substrate 1 by using a sputtering method such as a magnetron sputtering method or an ion beam sputtering method after fixing the substrate with a conductive film of the present invention to an electrostatic chuck. It is obtained by forming the reflective film 4.
The multilayer reflective film 4 formed on the film formation surface of the glass substrate 1 is not particularly limited as long as it has desired characteristics as the multilayer reflective film of the EUV mask blank. Here, the characteristic particularly required for the multilayer reflective film 4 is a film having a high EUV light reflectance. Specifically, when the multilayer reflective film surface is irradiated with light in the wavelength region of EUV light, the maximum value of light reflectance near the wavelength of 13.5 nm is preferably 60% or more, and is 65% or more. It is more preferable.
As the multilayer reflective film 4 satisfying the above characteristics, a Si / Mo multilayer reflective film in which Si films and Mo films are alternately laminated, a Be / Mo multilayer reflective film in which Be and Mo films are alternately laminated, Si Si compound / Mo compound multilayer reflective film in which compound and Mo compound layer are alternately laminated, Si film, Mo film, and Ru film are laminated in this order Si / Mo / Ru multilayer reflective film, Si film, Ru film And a Si / Ru / Mo / Ru multilayer reflective film in which a Mo film and a Ru film are laminated in this order.

The procedure for forming the multilayer reflective film 4 on the film formation surface of the glass substrate 1 may be a procedure that is normally performed when the multilayer reflective film is formed by sputtering. For example, when an Si / Mo multilayer reflective film is formed by ion beam sputtering, an Si target is used as a target, and Ar gas (gas pressure 1.3 × 10 ⁻² Pa to 2.7 × 10 ⁻ is used as a sputtering gas. ² Pa), an Si film is formed to have a thickness of 4.5 nm at an ion acceleration voltage of 300 to 1500 V and a film formation rate of 0.03 to 0.30 nm / sec. using a target, using an Ar gas (gas pressure ^{1.3 × 10 -2 Pa~2.7 × 10 -2} Pa), an ion acceleration voltage 300 to 1,500 V, the deposition rate of 0.03 to 0 It is preferable to form the Mo film so that the thickness is 2.3 nm at 30 nm / sec. With this as one period, the Si / Mo multilayer reflective film is formed by laminating the Si film and the Mo film for 40 to 50 periods. When forming the multilayer reflective film 4, it is preferable to perform film formation while rotating the glass substrate 1 using a rotating body in order to obtain uniform film formation.

  In the substrate with a multilayer reflective film of the present invention, the uppermost layer of the multilayer reflective film 4 is preferably made of a material that is difficult to oxidize in order to prevent the surface of the multilayer reflective film 4 from being oxidized. The layer of a material that is not easily oxidized functions as a cap layer of the multilayer reflective film 4. As a specific example of the layer of a material that hardly functions to be oxidized and functions as a cap layer, a Si layer can be exemplified. When the multilayer reflective film is a Si / Mo film, the uppermost layer can be made to function as a cap layer by making the uppermost layer an Si layer. In that case, the thickness of the cap layer is preferably 11 ± 2 nm.

  Since the substrate with a multilayer reflective film of the present invention uses the substrate with a conductive film of the present invention, when the multilayer reflective film is formed by fixing the substrate with a conductive film to the electrostatic chuck, the conductive film with the electrostatic chuck is electrically conductive. Generation of particles due to rubbing with the film is prevented. For this reason, it is an excellent multilayer reflective film-coated substrate with very few surface defects due to particles.

  Next, the EUV mask blank of the present invention will be described. FIG. 5 is a schematic view of the EUV mask blank of the present invention. In FIG. 5, an absorption layer 5 is provided on the multilayer reflective film 4. Here, the glass substrate 1, the intermediate film 3, the conductive film 2, and the multilayer reflective film 4 are those shown in FIG. 4 (the substrate with the multilayer reflective film of the present invention). In the EUV mask blank of the present invention, after the substrate with the multilayer reflective film of the present invention is fixed to the electrostatic chuck, the absorbing layer 5 is formed on the multilayer reflective film 4 by using a sputtering method such as a magnetron sputtering method or an ion beam sputtering method. It is obtained by forming a film.

  In the EUV mask blank of the present invention, the constituent material of the absorption layer 5 formed on the multilayer reflective film 4 is a material having a high absorption coefficient for EUV light, specifically, Cr, Ta and nitrides thereof. Is mentioned. Among them, TaN is preferable because it is easily amorphous and has excellent surface smoothness and low surface roughness. The thickness of the absorption layer 5 is preferably 50 to 100 nm. The method for forming the absorption layer 5 is not particularly limited as long as it is a sputtering method, and may be either a magnetron sputtering method or an ion beam sputtering method.

When a TaN layer is formed as an absorption layer using an ion beam sputtering method, a Ta target is used as a target, and an N ₂ gas (gas pressure 1.3 × 10 ⁻² Pa to 2.7 × 10 ⁻ is used as a sputtering gas. ² Pa) is preferably used to form a film at a voltage of 300 to 1500 V and a film formation rate of 0.01 to 0.1 nm / sec to a thickness of 50 to 100 nm.
When forming the absorption layer 5 using the sputtering method, it is preferable to perform the film formation while rotating the glass substrate 1 using a rotating body in order to obtain a uniform film formation.

In the EUV mask blank of the present invention, a buffer layer may exist between the multilayer reflective film 4 and the absorption layer 5.
Examples of the material constituting the buffer layer include Cr, Al, Ru, Ta, and nitrides thereof, and SiO ₂ , Si ₃ N ₄ , Al ₂ O _{3, and the} like. The buffer layer is preferably 10 to 60 nm thick.

Since the EUV mask blank of the present invention uses the substrate with a multilayer reflective film of the present invention, the multilayer reflective film has very few surface defects due to particles. In addition, when the absorption layer is formed by fixing the multilayer reflective film-coated substrate to the electrostatic chuck, generation of particles due to friction between the electrostatic chuck and the conductive film is prevented. For this reason, the absorption layer also has very few surface defects due to particles.
Furthermore, it is possible to form an EUV mask with few surface defects by patterning the EUV mask blank. By reducing defects, exposure with few defects can be performed, and productivity is excellent.

When forming a pattern on an EUV mask blank, that is, during a mask patterning process, in order to form a fine pattern, pattern formation is usually performed using an electron beam drawing technique.
In order to form a pattern using the electron beam lithography technique, first, a resist for electron beam lithography is applied to the surface of the absorption layer of the EUV mask blank, and a baking process, for example, a baking process at 200 ° C. is performed. Next, a resist pattern is formed by irradiating the resist surface with an electron beam using an electron beam drawing apparatus and then developing. The mask patterned by the above procedure is subjected to an exposure process using EUV light. These procedures are performed with the EUV mask blank (or patterned mask) secured to the electrostatic chuck.
During the pattern formation or the exposure with EUV light, the temperature of the glass substrate rises. An increase in temperature of the glass substrate is not preferable because it may adversely affect pattern accuracy. For this reason, cooling the glass substrate during pattern formation has been studied. Various methods for cooling the glass substrate are conceivable. For example, a method of cooling the substrate by circulating a liquid or gas inside the electrostatic chuck, or a method of circulating a gas through the gap between the pin chuck and the substrate. There is a method of cooling the substrate. In these methods, from the viewpoint of cooling efficiency of the glass substrate, it is preferable that the adhesion between the conductive film 2 and the electrostatic chuck is high and the thermal conductivity at the contact portion between the two is high. The EUV mask blank of the present invention is suitable in this respect because the adhesiveness between the conductive film 2 and the electrostatic chuck is high.

The present invention will be further described below using examples.
Example 1
In this example, a substrate with a conductive film shown in FIG. 1, that is, a substrate with a conductive film in which the intermediate film 3 and the conductive film 2 were formed in this order on one surface of the glass substrate 1 was produced.
As the glass substrate 1 for film formation, a SiO ₂ —TiO ₂ glass substrate (outer dimensions 6 inches (152.4 mm) square, thickness 6.3 mm) was used.
Formation of Intermediate Film 3 On the surface of the glass substrate 1, a CrON film was formed as the intermediate film 3 by using a magnetron sputtering method. Specifically, after the inside of the film forming chamber is evacuated to 1 × 10 ⁻⁴ Pa or less, magnetron sputtering is performed using a Cr target in a mixed gas atmosphere of Ar, O _2, and N ₂ to obtain a thickness of 30 nm. An intermediate film 3 (CrON film) was formed. The conditions for forming the intermediate film 3 (CrON film) are as follows.
Target: Cr target sputtering gas: mixed gas of Ar, O ₂ and N ₂ (Ar: 36 vol%, O ₂ : 50 vol%, N ₂ : 14 vol%, gas pressure: 0.3 Pa)
Input power: 150W
Deposition rate: 0.11 nm / sec
Film thickness: 30nm
Composition analysis of the intermediate film 3 (CrON film) The composition of the intermediate film 3 (CrON film) was measured using an X-ray Photoelectron Spectrometer (manufactured by PERKIN ELMER-PHI), Rutherford Backscatter Spectrometer (Rutherford Back). It measures using Scattering Spectroscopy (made by Kobe Steel). The composition ratio (at%) of the intermediate film 3 (CrON film) is Cr: O: N = 25: 65: 10.
Optical constant of the intermediate film 3 (CrON film) The refractive index (n) and extinction coefficient (k) of the intermediate film 3 (CrON film) with respect to the wavelength of 190 to 400 nm are measured by a spectroscopic ellipsometer (manufactured by JA Woollam). Were n = 1.70-2.11 and k = 0.10-0.83.

Formation of Conductive Film 2 Next, a CrN film was formed as the conductive film 2 on the intermediate film 3 by using a magnetron sputtering method. Specifically, after the inside of the film formation chamber is evacuated to 1 × 10 ⁻⁴ Pa or less, magnetron sputtering is performed in a mixed gas atmosphere of Ar and N ₂ using a Cr target to form a conductive film having a thickness of 40 nm. 2 (CrN film) was formed. The conditions for forming the conductive film 2 (CrN film) are as follows.
Target: Cr target sputtering gas: Ar and N ₂ mixed gas (Ar: 70 vol%, N ₂ : 30 vol%, gas pressure: 0.3 Pa)
Input power: 150W
Deposition rate: 0.11 nm / sec
Film thickness: 40nm
Composition analysis of conductive film 2 (CrN film) The composition of the conductive film 2 (CrN film) was measured using an X-ray photoelectron spectrometer. The composition ratio (at%) of the conductive film 2 (CrN film) is Cr: N = 63.1: 36.9.

Reflectance characteristics About the substrate with the conductive film obtained by the above procedure, light is emitted from the surface of the glass substrate 1 where the conductive film 2 and the intermediate film 3 are not formed (the surface above the glass substrate 1 in FIG. 1). The reflectivity in the vacuum ultraviolet region (190 to 400 nm) from the conductive film 2 side when incident was measured. The reflectance measurement was performed using a spectrophotometer (U-4100, manufactured by Hitachi High-Technologies Corporation). The reflectivity in the vacuum ultraviolet region (190 to 400 nm) is 10% or less, and by providing the intermediate film 3, the reflectivity can be 10% or less for all wavelengths of 190 to 400 nm. It was possible.

(Example 2)
This example is the same as Example 1 except that a CrO film is formed as the intermediate film 3 by the following procedure.
Formation of Intermediate Film 3 (CrO Film) A CrO film was formed as the intermediate film 3 on the surface of the glass substrate 1 by using a magnetron sputtering method. Specifically, after the inside of the film forming chamber is evacuated to 1 × 10 ⁻⁴ Pa or less, magnetron sputtering is performed in a mixed gas atmosphere of Ar and O ₂ using a Cr target to form an intermediate film having a thickness of 30 nm. 3 (CrO film) was formed. The film forming conditions for the intermediate film 3 (CrO film) are as follows.
Target: Cr target Sputtering gas: Mixed gas of Ar and O ₂ (Ar: 36 vol%, O ₂ : 64 vol%, gas pressure: 0.3 Pa)
Input power: 150W
Deposition rate: 0.15 nm / sec
Film thickness: 30nm
Composition analysis of the intermediate film 3 (CrO film) The composition of the intermediate film 3 (CrO film) was measured using an X-ray photoelectron spectrometer (manufactured by PERKIN ELMER-PHI), Rutherford backscattering spectrometer (Rutherford Back). It measures using Scattering Spectroscopy (made by Kobe Steel). The composition ratio (at%) of the intermediate film 3 (CrO film) is Cr: O = 25: 75.
When the refractive index (n) and extinction coefficient (k) of the intermediate film 3 (CrO film) with respect to the wavelength of 190 to 400 nm of the intermediate film 3 (CrO film) were measured in the same manner as in Example 1, n = 1. .68-2.20 and k = 0.10-0.93.

Reflectivity characteristics For the substrate with a conductive film obtained by the above procedure, the reflectance in the vacuum ultraviolet region (190 to 400 nm) from the conductive film side was measured in the same procedure as in Example 1. The reflectivity in the vacuum ultraviolet region (190 to 400 nm) is 10% or less, and by providing the intermediate film 3, the reflectivity can be 10% or less for all wavelengths of 190 to 400 nm. It was possible.

(Example 3)
This example is the same as Example 1 except that a TaON film is formed as the intermediate film 3 by the following procedure.
A TaON film was formed as the intermediate film 3 on the surface of the glass substrate 1 by using a magnetron sputtering method. Specifically, after the inside of the film forming chamber is evacuated to 1 × 10 ⁻⁴ Pa or less, magnetron sputtering is performed using a Ta target in a mixed gas atmosphere of Ar, O _2, and N ₂ to a thickness of 10 nm. An intermediate film 3 (TaON film) was formed.
Film formation conditions for intermediate film 3 (TaON film) Target: Ta target Sputter gas: Mixed gas of Ar, O ₂ and N ₂ (Ar: 36 vol%, O ₂ : 50 vol%, N ₂ : 14 vol%, Gas pressure: 0.3Pa)
Input power: 450W
Deposition rate: 1.1 nm / min
Film thickness: 10nm
Composition analysis of the intermediate film 3 (TaON film) The composition of the intermediate film 3 (TaON film) was measured using an X-ray photoelectron spectrometer (manufactured by PERKIN ELEMER-PHI), Rutherford backscattering spectrometer (Rutherford Back). It measures using Scattering Spectroscopy (made by Kobe Steel). The composition ratio (at%) of the intermediate film 3 (TaON film) is Ta: O: N = 24: 70: 6.
When the refractive index (n) and extinction coefficient (k) with respect to the wavelength of 190 to 400 nm of the optical constant intermediate film 3 (TaON film) of the intermediate film 3 were measured in the same manner as in Example 1, n = 1.90-2. .99 and k = 0.0-0.98.

Reflectivity characteristics For the substrate with a conductive film obtained by the above procedure, the reflectance in the vacuum ultraviolet region (190 to 400 nm) from the conductive film side was measured in the same procedure as in Example 1. The reflectivity in the vacuum ultraviolet region (190 to 400 nm) is 10% or less, and by providing the intermediate film 3, the reflectivity can be 10% or less for all wavelengths of 190 to 400 nm. It was possible.

Example 4
This example is the same as Example 1 except that a TaO film is formed as the intermediate film 3 by the following procedure.
Formation of Intermediate Film 3 (TaO Film) A TaO film was formed as the intermediate film 3 on the surface of the glass substrate 1 by using a magnetron sputtering method. Specifically, after the inside of the film forming chamber is evacuated to 1 × 10 ⁻⁴ Pa or less, magnetron sputtering is performed in a mixed gas atmosphere of Ar and O ₂ using a Cr target to form an intermediate film having a thickness of 30 nm. 3 (TaO film) was formed. The deposition conditions for the intermediate film 3 (TaO film) are as follows.
Deposition conditions <br/> target intermediate film 3 (TaO film): Ta target Sputtering gas: mixed gas of Ar and _{O 2 (Ar: 36vol%,} O 2: 64vol%, gas pressure: 0.3 Pa)
Input power: 150W
Deposition rate: 0.21 nm / sec
Film thickness: 30nm
Composition analysis of the intermediate film 3 (TaO film) The composition of the intermediate film 3 (TaO film) was measured using an X-ray photoelectron spectrometer (manufactured by PERKIN ELEMER-PHI), Rutherford backscattering spectrometer (Rutherford Back). It measures using Scattering Spectroscopy (made by Kobe Steel). The composition ratio (at%) of the intermediate film 3 (TaO film) is Ta: O = 24: 76.
The optical constant of the intermediate film 3 (TaO film) The refractive index (n) and extinction coefficient (k) of the intermediate film 3 (TaO film) with respect to the wavelength of 190 to 400 nm were measured in the same manner as in Example 1. 0.95 to 2.89 and k = 0.0 to 0.95.

Reflectivity characteristics For the substrate with a conductive film obtained by the above procedure, the reflectance in the vacuum ultraviolet region (190 to 400 nm) from the conductive film side was measured in the same procedure as in Example 1. The reflectivity in the vacuum ultraviolet region (190 to 400 nm) is 10% or less, and by providing the intermediate film 3, the reflectivity can be 10% or less for all wavelengths of 190 to 400 nm. It was possible.

(Comparative Example 1)
This comparative example is the same as Example 1 except that the intermediate film 3 is not provided. That is, a CrN film having a thickness of 40 nm was formed on the glass substrate 1 as the conductive film 2 under the conditions described in Example 1.
About the board | substrate with an electrically conductive film obtained by said procedure, the reflectance of the vacuum ultraviolet region (190-400 nm) from the electrically conductive film side was measured in the procedure similar to Example 1. FIG. In the vacuum ultraviolet region (190 to 400 nm), the reflectivity for a wavelength of 190 to 290 nm was 10% or less, but the reflectivity for a wavelength of 290 to 400 nm was 10% or more, and in the vacuum ultraviolet region (190 to 400 nm). The reflectivity could not be made 10% or less in all wavelength ranges.

(Comparative Example 2)
This comparative example is the same as Example 1 except that the composition of the intermediate film 3 is different, so that the extinction coefficient k of the intermediate film 3 exceeds 1.0.
By adjusting the film formation conditions of the intermediate film 3 (CrON film) on the glass substrate 1, the intermediate film 3 (CrON film, which has a composition ratio (at%) of Cr: O: N = 25: 5: 75, A film thickness of 30 nm) was formed. The optical constant of the intermediate film 3 (CrON film) was measured in the same manner as in Example 1. As a result, n = 1.50 to 2.21, k = 1.40 to 2.10, and the extinction coefficient k was 1. More than 0.0.
Next, a conductive film 2 (CrN) having a thickness of 40 nm was formed in the same procedure as in Example 1, and the reflectance in the vacuum ultraviolet region (190 to 400 nm) from the conductive film side was measured. The reflectance did not fall below 10% in the entire wavelength range of the region (190 to 400 nm).

1: Glass substrate 2: Conductive film 3: Intermediate film 4: Multilayer reflective film 5: Absorbing layer

Claims (8)

  A conductive film-formed substrate used in the manufacture of a reflective mask blank for EUV lithography, wherein a conductive film is formed on a glass substrate, having an intermediate film between the glass substrate and the conductive film, The intermediate film has a refractive index (n) in the range of 1.47 to 3.00 and an extinction coefficient (k) in the range of 0 to 1.0 with respect to a wavelength of 190 nm to 400 nm. The total film thickness of the said electrically conductive film is 50-200 nm, The board | substrate with an electrically conductive film characterized by the above-mentioned.   The intermediate film contains at least one selected from the group consisting of chromium (Cr) and tantalum (Ta) and oxygen (O), and the total content of chromium (Cr) and tantalum (Ta) is 10 to 10. The substrate with conductive film according to claim 1, wherein the substrate has a content of 90 at% and an oxygen (O) content of 10 to 90 at%.   The intermediate film contains at least one selected from the group consisting of chromium (Cr) and tantalum (Ta), oxygen (O) and nitrogen (N), and the total content of chromium (Cr) and tantalum (Ta). Is 10 to 80 at%, the total content of oxygen (O) and nitrogen (N) is 20 to 90 at%, and the composition ratio of O and N is O: N = 9: 1 to 5: 5 The substrate with a conductive film according to claim 1.   The conductive film includes at least one selected from the group consisting of chromium (Cr) and tantalum (Ta), and nitrogen (N), and the conductive film contains a total of chromium (Cr) and tantalum (Ta). The rate is 60 at% or more and less than 99.9 at%, and the content ratio of nitrogen (N) is 0.1 at% or more and less than 40 at%. substrate.   The sheet resistance value of the said intermediate film and a electrically conductive film is 0.1-100 ohms / square, The board | substrate with an electrically conductive film in any one of Claims 1-4 characterized by the above-mentioned.   The multilayer reflective film of the reflective mask blank for EUV lithography which forms a multilayer reflective film in the opposite side with respect to the surface in which the said electrically conductive film of the board | substrate with a conductive film in any one of Claims 1-5 was provided. Attached substrate.   A reflective mask blank for EUV lithography, comprising an absorption layer formed on the multilayer reflective film of the multilayer reflective film-coated substrate according to claim 6.   The reflective mask for EUV lithography which patterned the reflective mask blank for EUV lithography of Claim 7.

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