JP6186996B2 - Reflective mask blank for EUV lithography and reflective mask for EUV lithography - Google Patents

Description

  The present invention relates to a reflective mask blank (hereinafter also referred to as “EUV mask blank”) for EUV (Extreme Ultra Violet) lithography used in semiconductor manufacturing and the like, and the EUV mask blank. The present invention relates to a reflective mask for EUV lithography (hereinafter also referred to as “EUV mask” in the present specification) formed by forming a mask pattern on the absorption layer.

  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 Si 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 light in the EUV wavelength region shorter than the ArF laser (hereinafter referred to as “EUV light”), 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 cannot be used. For this reason, in the EUV light lithography, a reflective optical system, that is, an EUV mask 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 a reflective layer, a low refractive index layer having a low refractive index with respect to EUV light and a high refractive index layer having a high refractive index with respect to EUV light are alternately laminated, so that EUV light is applied to the surface of the layer. A multilayer reflective film having an increased light reflectance upon irradiation is usually used. As the low refractive index layer of the multilayer reflective film, a molybdenum (Mo) layer is usually used, and as the high refractive index layer, a silicon (Si) layer 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 means for supporting a silicon (Si) 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 Si wafer. There is sex.
In order to solve such a problem, Patent Document 1 discloses a multilayer reflection in which a conductive film (back conductive film) is formed on the opposite side of the multilayer reflective film across the substrate in order to promote electrostatic chucking of the substrate. A film substrate, a reflective mask blank for exposure, and a mask for exposure are described. This conductive film is a metal nitride film, and examples of the metal include chromium, tantalum, molybdenum, and silicon.

  In recent years, as the pattern becomes finer in EUV mask blanks, the effect of shadowing due to the thickness of the absorption layer (deterioration of pattern accuracy) has become a problem. It is being considered. This is a technique for achieving thinning of the absorbing layer by utilizing the phase effect between the EUV reflected light on the reflecting layer surface and the EUV reflected light on the absorbing layer surface. That is, the EUV reflected light on the surface of the absorbing layer is increased by making the absorbing layer thin, but the phase of the reflected light on the absorbing layer surface and the reflected light on the reflecting layer surface is shifted by 180 degrees to thereby increase the A sufficient 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 a 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.

  However, the light source used for EUV exposure includes not only EUV light (wavelength of about 10 to 20 nm) but also light in the vacuum ultraviolet region (wavelength of 190 to 400 nm). When the glass surface is exposed by etching the layer and the reflective layer, 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 causes unnecessary light on the Si wafer. The resist is exposed to light, which causes a problem that pattern accuracy deteriorates. In order to prevent such a problem, the reflectance with respect to light in the vacuum ultraviolet region (wavelength 190 to 400 nm) is required to be 20% or less.

  The present applicant suppresses reflection of light 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. The inventors found that the reflectance for light in the ultraviolet region (190 to 400 nm) can be 20% or less, and provided a reflective mask blank for EUV lithography described in Patent Document 3, and a substrate with a functional film for the mask blank.

Japanese Patent Laid-Open No. 2005-210093 JP 2002-217097 A JP 2012-49498 A

In the EUV mask and the EUV mask blank used therefor, there may be a problem of deformation of the substrate caused by internal reflection in the multilayer reflective film as the reflective layer or the absorbing layer. Conventionally, there has been a tendency to increase the film thickness of the back conductive film in order to offset this internal stress.
In addition, a glass substrate is locally irradiated by irradiating a pulse laser having a wavelength of 532 nm (any wavelength may be used in the wavelength range of 400 to 800 nm) from the back side of the EUV mask or EUV mask blank. A technique for improving the deformation of the substrate due to internal stress in the multilayer reflective film or the absorbing layer by heating to a new level is being introduced.
By applying this technique, the film thickness of the back surface conductive film can be set to a minimum film thickness necessary to achieve the requirements regarding the sheet resistance value. As a result, the time required for forming the back surface conductive film is shortened, and the yield in manufacturing the EUV mask blank is improved.
However, when this technique is applied, the back surface conductive film has a high light transmittance at a wavelength of 532 nm (an arbitrary wavelength may be used in the wavelength range of 400 to 800 nm), specifically, in this wavelength region. The light transmittance is required to be 10% or more. In general, to increase the light transmittance, the film thickness may be reduced. However, if the film thickness of the back surface conductive film is reduced, the sheet resistance value may increase, and there is a possibility that the requirement cannot be achieved.

  In order to solve the above-described problems of the prior art, the present invention can suppress the reflected light in the vacuum ultraviolet region (wavelength 190 to 400 nm) from the back conductive film, has a high light transmittance at a wavelength of 400 to 800 nm, and An object of the present invention is to provide an EUV mask blank having a low sheet resistance and having a back conductive film formed thereon.

In order to achieve the above-described object, according to the present invention, a reflective layer that reflects EUV light and an absorption layer that absorbs EUV light are formed in this order on one surface side of the substrate, and the other surface side of the substrate is formed. A reflective mask blank for EUV lithography in which a conductive film is formed on
An intermediate film is formed between the substrate and the conductive film,
The conductive film contains at least one selected from the group consisting of chromium (Cr) and tantalum (Ta), and nitrogen (N);
N content in the conductive film is 1 at% or more and 42 at% or less,
When the N content in the conductive film is C (at%) and the film thickness of the conductive film is t (nm), the following formula (1) is satisfied:
The intermediate film contains at least one selected from the group consisting of chromium (Cr) and tantalum (Ta) and oxygen (O), the total content of Cr and Ta is 10 to 70 at%, and O The EUV lithography is characterized in that the content of the intermediate film is 30 to 90 at%, the film thickness of the intermediate film is 10 nm or more and less than 48 nm, and the total film thickness of the intermediate film and the conductive film is 17 nm or more and less than 50 nm. A reflective mask blank for use is provided.
0.15C + 1.68 ≦ t ≦ 0.31C + 11.13 (1)

In the EUV mask blank of the present invention, the intermediate film may contain at least one of nitrogen (N), hydrogen (H), boron (B), silicon (Si), and hafnium (Hf) in a total content of 27 at%. You may contain below.
In the EUV mask blank of the present invention, the intermediate film contains nitrogen (N), the total content of Cr and Ta is 10 to 70 at%, and the total content of O and N is 30 to 90 at% The composition ratio of O and N is preferably less than O: N = 10: more than 0 to 7: 3.

  In the EUV mask blank of the present invention, the conductive film contains Cr and N, the Cr content in the conductive film is 58 at% or more and 99 at% or less, and the N content is 1 at% or more and 42 at%. The following is preferable.

  In the EUV mask blank of the present invention, the conductive film preferably has a thickness of 2 nm to 24 nm.

  In the EUV mask blank of the present invention, the conductive film surface preferably has a surface roughness (rms) of 0.5 nm or less.

  In the EUV mask blank of the present invention, the total content of aluminum (Al) and indium (In) in the conductive film is preferably 5 at% or less.

  In the EUV mask blank of the present invention, the total content of aluminum (Al) and indium (In) in the intermediate film is preferably 5 at% or less.

  In the EUV mask blank of the present invention, the sheet resistance value of the conductive film is preferably 250 Ω / □ or less.

  In the EUV mask blank of the present invention, the conductive film and the intermediate film preferably have a light transmittance of 10% or more at a wavelength of 400 to 800 nm.

  In the EUV mask blank of the present invention, it is preferable that the light reflectance when irradiating light having a wavelength of 190 to 400 nm from the substrate side exposed when the reflective layer and the absorbing layer are not provided is 20% or less. .

In the EUV mask blank of the present invention, a protective layer for protecting the reflective layer may be formed between the reflective layer and the absorbent layer when forming a pattern on the absorbent layer.
The protective layer preferably includes Ru or a Ru compound as a constituent material.

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

  The EUV mask of the present invention has a portion where the substrate is exposed without including the reflection layer and the absorption layer in a region outside the exposure region, and the portion is irradiated with light having a wavelength of 190 to 400 nm. The light reflectance at the time is preferably 20% or less.

Since the EUV mask blank and EUV mask of the present invention have a light transmittance of 10% or more at a wavelength of 400 to 800 nm of the back surface conductive film and the intermediate film, from the back side of the EUV mask blank or EUV mask, By locally irradiating the pulsed laser and locally heating the glass substrate, it is possible to improve the deformation of the substrate due to internal stress in the multilayer reflective film or the absorption layer. On the other hand, since the sheet resistance value of the back surface conductive film is as low as 250Ω / □ or less, the chucking force by the electrostatic chuck is high.
According to the EUV mask blank and EUV mask of the present invention, the reflection of light in the vacuum ultraviolet region (190 to 400 nm) from the back conductive film side is suppressed, and the reflectance for light in the vacuum ultraviolet region (wavelength 190 to 400 nm) is reduced. It can be made 20% or less.
For this reason, in the EUV mask blank and EUV mask of the present invention, when the glass substrate is exposed by etching the absorption layer and the reflection layer in the outer peripheral portion of the exposure region, the vacuum ultraviolet region from the outer peripheral portion of the exposure region The reflected light suppresses unnecessary resist on the Si wafer from being exposed, and the pattern accuracy is improved.

FIG. 1 is a schematic cross-sectional view showing an embodiment of the EUV mask blank of the present invention. FIG. 2 is a graph showing the relationship between the N content in the conductive film and the film thickness of the back conductive film for Examples 1 to 15 (reference example). FIG. 3 is a graph showing the light transmittance and light reflectance at a wavelength of 190 to 800 nm for Example 16. FIG. 4 is a graph comparing the light transmittance at a wavelength of 400 to 800 nm with respect to Example 16 as compared with the case where no intermediate film was formed. FIG. 5 is a graph showing the light transmittance and light reflectance of Example 190 with a wavelength of 190 to 800 nm. FIG. 6 is a graph comparing the light transmittance at a wavelength of 400 to 800 nm with respect to Example 17 as compared with the case where no intermediate film was formed. FIG. 7 is a graph showing the light transmittance and light reflectance of Example 190 with a wavelength of 190 to 800 nm. FIG. 8 is a graph showing the light transmittance and light reflectance of Example 190 with a wavelength of 190 to 800 nm. FIG. 9 is a graph showing the light transmittance and light reflectance of Example 190 with a wavelength of 190 to 800 nm. FIG. 10 is a graph showing the light transmittance and light reflectance of Example 190 with a wavelength of 190 to 800 nm. FIG. 11 is a graph showing the light transmittance and light reflectance of Example 190 with a wavelength of 190 to 800 nm. FIG. 12 is a graph showing the light transmittance and light reflectance at a wavelength of 190 to 800 nm for Example 23. FIG. 13 is a graph showing the light transmittance and light reflectance at a wavelength of 190 to 800 nm for Example 24. FIG. 14 is a graph showing light transmittance and light reflectance at a wavelength of 190 to 800 nm for Example 25.

Hereinafter, the EUV mask blank of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic cross-sectional view showing an embodiment of the EUV mask blank of the present invention. In the mask blank shown in FIG. 1, a reflective layer 2 that reflects EUV light and an absorption layer 3 that absorbs EUV light are formed in this order on one surface of the substrate 1 (the upper surface of the substrate 1 in the figure). ing. A conductive film (back conductive film) 4 is formed on the other surface of the substrate 1 (the lower surface of the substrate 1 in the figure). An intermediate film 5 is formed between the substrate 1 and the conductive film 4.
Hereinafter, individual components of the mask blank of the present invention will be described.

The substrate 1 is required to satisfy characteristics as a substrate for an EUV mask blank.
Therefore, the substrate 1 has a low thermal expansion coefficient (specifically, the thermal expansion coefficient at 20 ° C. is preferably 0 ± 1.0 × 10 ⁻⁷ / ° C., more preferably 0 ± 0.3 × 10 ⁻⁷ / ° C. More preferably 0 ± 0.2 × 10 ⁻⁷ / ° C., further preferably 0 ± 0.1 × 10 ⁻⁷ / ° C., particularly preferably 0 ± 0.05 × 10 ⁻⁷ / ° C.) Those having excellent smoothness, flatness, and resistance to a cleaning liquid used for cleaning a mask blank or a photomask after pattern formation are preferred. Specifically, the substrate 1 is made of glass having a low thermal expansion coefficient, such as SiO ₂ —TiO ₂ glass, but is not limited to this. Crystallized glass, quartz glass, silicon, A substrate such as metal can also be used. Further, a film such as a stress correction film may be formed on the substrate 1.

The substrate 1 has a smooth surface with a surface roughness (rms) of 0.15 nm or less and a flatness of 100 nm or less in the standard of JIS-B0601, and high EUV light reflection in a photomask after pattern formation. Rate and transfer accuracy are preferable.
The size and thickness of the 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 mm) square and a thickness of 0.25 inches (6.3 mm) was used.
It is preferable that no defects exist on the surface of the substrate 1 on the side where the reflective layer 2 is formed. However, even if it exists, the depth of the concave defect and the height of the convex defect are not more than 2 nm so that the phase defect does not occur due to the concave defect and / or the convex defect. It is preferable that the half width of the defect and the convex defect is 60 nm or less.

  The reflective layer 2 is required to have a particularly high EUV light reflectivity as a reflective layer of an EUV mask blank. Specifically, when the surface of the reflective layer 2 is irradiated with EUV light at an incident angle of 6 degrees, the maximum value of the light reflectance near the wavelength of 13.5 nm is preferably 60% or more, more preferably 63% or more, 65% or more is more preferable.

  Since the reflective layer 2 can achieve a high EUV light reflectance, normally, a high refractive layer that exhibits a high refractive index for EUV light and a low refractive index layer that exhibits a low refractive index for EUV light are alternately alternated. A multilayer reflective film laminated a plurality of times is used. In the multilayer reflective film constituting the reflective layer 2, Si is widely used for the high refractive index layer, and Mo is widely used for the low refractive index layer. That is, the Mo / Si multilayer reflective film is the most common. However, the multilayer reflective film is not limited to this, and Ru / Si multilayer reflective film, Mo / Be multilayer reflective film, Mo compound / Si compound multilayer reflective film, Si / Mo / Ru multilayer reflective film, Si / Mo / Ru / Mo multilayer reflective films and Si / Ru / Mo / Ru multilayer reflective films can also be used.

  The thickness of each layer constituting the multilayer reflective film constituting the reflective layer 2 and the number of repeating units of the layers can be appropriately selected according to the film material used and the reflectance of EUV light required for the reflective layer. Taking a Mo / Si multilayer reflective film as an example, in order to obtain a reflective layer 2 having a maximum EUV light reflectance of 60% or more, the multilayer reflective film is made of a Mo film having a film thickness of 2.3 ± 0.1 nm. A Si film having a thickness of 4.5 ± 0.1 nm may be laminated so that the number of repeating units is 30 to 60.

In addition, what is necessary is just to form each layer which comprises the multilayer reflective film which comprises the reflective layer 2 so that it may become desired thickness using well-known film-forming methods, such as a magnetron sputtering method and an ion beam sputtering method. For example, when forming a Mo / Si multilayer reflective film using 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 acceleration film having a thickness of 4.5 nm is formed at an ion acceleration voltage of 300 to 1500 V and a film formation speed of 0.03 to 0.30 nm / sec. using Mo target, Ar gas as a sputtering gas (gas ^{pressure: 1.3 × 10 -2 Pa~2.7 × 10} -2 Pa) using an ion acceleration voltage 300 to 1,500 V, the deposition rate 0.03 It is preferable to form the Mo film so that the thickness is 2.3 nm at ˜0.30 nm / sec. With this as one period, the Mo / Si multilayer reflective film is formed by laminating 30 to 60 periods of the Si film and the Mo film.

The characteristic particularly required for the absorption layer 3 is that the EUV light reflectance is extremely low. Specifically, the maximum light reflectance around a wavelength of 13.5 nm when the surface of the absorbing layer 3 is irradiated with light in the wavelength region of EUV light is preferably 0.5% or less, more preferably 0.1% or less. preferable.
In order to achieve the above characteristics, the absorption layer 3 is made of a material having a high EUV light absorption coefficient. As a material having a high EUV light absorption coefficient, a material mainly composed of tantalum (Ta) is preferably used. In this specification, the term “material mainly composed of tantalum (Ta)” means a material containing 40 at% or more of Ta in the material. The absorption layer 3 preferably contains 50 at% or more of Ta, more preferably 55 at% or more.

  In addition to Ta, the material mainly composed of Ta used for the absorption layer 3 is hafnium (Hf), silicon (Si), zirconium (Zr), germanium (Ge), boron (B), palladium (Pd), hydrogen (H ) And nitrogen (N). Specific examples of the material containing the above elements other than Ta include, for example, TaN, TaNH, TaHf, TaHfN, TaBSi, TaBSiN, TaB, TaBN, TaSi, TaSiN, TaGe, TaGeN, TaZr, TaZrN, TaPd, TaPdN, etc. Is mentioned.

Moreover, the thickness of the absorption layer 3 is preferably in the range of 50 to 100 nm.
The absorption layer 3 having the above-described configuration can be formed using a film forming method such as a sputtering method such as a magnetron sputtering method or an ion beam sputtering method.
For example, when a TaNH film is formed as the absorption layer 3 by using a magnetron sputtering method, a Ta target is used as a target, and a mixed gas of Ar, N ₂ and H ₂ (H ₂ gas concentration: 1 to 30 vol) as a sputtering gas. %, N ₂ gas concentration: 5 to 75 vol%, Ar gas concentration: 10 to 94 vol%, gas pressure: 0.5 × 10 ⁻¹ Pa to 1.0 Pa), input power 300 to 2000 W, film formation rate 0.5 It is preferable to form a film so as to have a thickness of 20 to 90 nm at ˜60 nm / min.

A characteristic required for the conductive film 4 is a low sheet resistance value. In the present invention, the sheet resistance value of the conductive film 4 is 250Ω / □ or less. The sheet resistance value is preferably 200Ω / □ or less, more preferably 150Ω / □ or less, further preferably 100Ω / □ or less, and particularly preferably 80Ω / □ or less.
Furthermore, as a characteristic requested | required of the electrically conductive film 4 of the EUV mask blank and EUV mask which concerns on this invention, it is mentioned that the light transmittance of wavelength 400-800 nm is high. This is because, by locally irradiating the pulse laser in this wavelength region and locally heating the glass substrate, deformation of the substrate due to internal stress in the multilayer reflective film or the absorption layer can be improved. In the EUV mask blank and EUV mask according to the present invention, the light transmittance of the conductive film 4 and the intermediate film 5 at a wavelength of 400 to 800 nm has a characteristic of 10% or more. In addition, the light transmittance at a wavelength of 400 to 800 nm of the EUV mask blank, the conductive film 4 and the intermediate film 5 of the EUV mask according to the present invention is preferably 13% or more, more preferably 15% or more, and further preferably 20% or more. preferable.

In order to achieve the above required characteristics, the EUV mask blank according to the present invention, the conductive film 4 of the EUV mask, at least one selected from the group consisting of chromium (Cr) and tantalum (Ta), nitrogen (N), Containing. Specific examples of the conductive film 4 include a CrN film, a TaN film, and a CrTaN film.
Among these, a CrN film is preferable in that it has high resistance to chemicals such as alkali and acid used at the time of general mask blank cleaning and mask cleaning.

In the conductive film 4 of the EUV mask blank and EUV mask according to the present invention, the content of nitrogen (N) in the conductive film is 1 at% or more and 42 at% or less. When the N content in the conductive film 4 is less than 1 at%, there are problems that the surface smoothness of the conductive film 4 decreases and the surface hardness of the conductive film 4 decreases. Since these problems cause film peeling during electrostatic chucking, the conductive film 4 is required to have excellent surface smoothness and high surface hardness. On the other hand, if the N content in the conductive film 4 exceeds 42 at%, the sheet resistance value of the conductive film 4 increases.
Further, the N content in the conductive film 4 is preferably 1 at% or more and 40 at% or less, more preferably 1 at% or more and 38 at% or less, further preferably 5 at% or more and 38 at% or less, and particularly preferably 5 at% or more and 35 at% or less. .

In the EUV mask blank and the conductive film 4 of the EUV mask according to the present invention, the balance obtained by subtracting the N content is usually the content of chromium (Cr) and tantalum (Ta). Therefore, the total content of Cr and Ta is 58 at% or more and 99% or less, preferably 60 at% or more and 99% or less, more preferably 62 at% or more and 99 at% or less, further preferably 62 at% or more and 95 at% or less, and 65 at % To 95 at% is particularly preferable.
The conductive film 4 of the EUV mask blank or EUV mask according to the present invention may contain elements other than Cr, Ta, and N as long as the function as the conductive film is not impaired.
However, it is preferable not to contain an element having a higher light absorption coefficient for light having a wavelength of 400 to 800 nm than Cr and Ta. Specific examples of such elements include aluminum (Al) and indium (In).
When the total content of Al and In is 5 at% or less in the conductive film 4 of the EUV mask blank and EUV mask according to the present invention, the light absorption in the conductive film is reduced, and the light transmittance at a wavelength of 400 to 800 nm. Is preferable when the content is 10% or more. The total content of Al and In is preferably 3 at% or less, more preferably 1 at% or less, and still more preferably substantially not contained.

The conductive film 4 of the EUV mask blank and EUV mask according to the present invention has the following formula when the nitrogen (N) content in the conductive film is C (at%) and the film thickness of the conductive film is t (nm). The N content in the conductive film and the film thickness of the conductive film are set so as to satisfy the above. This satisfies both the sheet resistance value of 250Ω / □ or less and the light transmittance of 10% or more at a wavelength of 400 to 800 nm.
0.15C + 1.68 ≦ t ≦ 0.31C + 11.13
When t <0.15C + 1.68, the sheet resistance value increases and exceeds 250Ω / □.
On the other hand, if t ≧ 0.15C + 1.68, the sheet resistance value is 250Ω / □ or less.
On the other hand, when t> 0.31C + 11.13, the light transmittance at a wavelength of 400 to 800 nm is reduced to less than 10%. On the other hand, if t ≦ 0.31C + 11.13, the light transmittance at a wavelength of 400 to 800 nm is 10% or more.

  The thickness of the conductive film 4 of the EUV mask blank or EUV mask according to the present invention is preferably selected from the range of 2 nm to 24 nm so as to satisfy the above inequality. If the film thickness of the conductive film 4 is less than 2 nm, the sheet resistance value increases and it is difficult to make the sheet resistance value 250 Ω / □ or less. On the other hand, when the film thickness of the conductive film 4 exceeds 24 nm, the light transmittance at a wavelength of 400 to 800 nm decreases, and it is difficult to set the light transmittance to 10% or more.

The EUV mask blank and the conductive film 4 of the EUV mask according to the present invention preferably have a surface roughness (rms) of the conductive film surface of 0.5 nm or less. If the surface roughness of the conductive film is large, the light transmittance may decrease due to light scattering. If the surface roughness (rms) on the surface of the conductive film is 0.5 nm or less, it is preferable for reducing light scattering and making the light transmittance at a wavelength of 400 to 800 nm 10% or more.
Further, when the surface roughness (rms) of the surface of the conductive film is 0.5 nm or less, the conductive film is excellent in surface smoothness, which is preferable from the viewpoint of preventing film peeling during electrostatic chucking.
The surface roughness (rms) of the conductive film surface is more preferably 0.4 nm or less, and further preferably 0.3 nm or less. The surface roughness (rms) can be evaluated based on the standard of JIS-B0601.

The EUV mask blank and the EUV mask conductive film 4 according to the present invention can be formed by a known film forming method, for example, a sputtering method such as a magnetron sputtering method or an ion beam sputtering method. When the conductive film 4 is formed by sputtering, an inert gas containing at least one of helium (He), argon (Ar), neon (Ne), krypton (Kr), and xenon (Xe), and nitrogen (N ₂ ) and the sputtering method may be performed using a Cr target and / or a Ta target.

In order to form the conductive film 4 by the magnetron sputtering 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: 3-45 vol%, preferably 5-40 vol%, more preferably 10-35 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 to 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: Mixed gas of Ar and N ₂ (N ₂ gas concentration: 3-45 vol%, preferably 5-40 vol%, more preferably 10-35 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

The intermediate film 5 formed between the substrate 1 and the conductive film 4 suppresses the reflected light in the vacuum ultraviolet region (190 to 400 nm) from the conductive film 4 and reflects the light in the vacuum ultraviolet region (190 to 400 nm). It bears the function of setting the rate to 20% or less. The reflected light from the conductive film 4 here does not occur when light incident on the surface of the conductive film 4 from below in the figure is reflected by the surface of the conductive film 4, but is reflected light defined below. Means. That is, the reflected light from the conductive film 4 here is when light in the vacuum ultraviolet region (190 to 400 nm) is irradiated from the exposed substrate 1 side when the reflective layer 2 and the absorption layer 3 are not provided. The reflected light reflected from the surface of the substrate 1 and the light transmitted through the substrate 1 from above in the figure are reflected at the interface between the substrate 1 and the intermediate film 5, and the intermediate film 5 and the conductive film 4 The light produced by combining the reflected light reflected at the interface and the reflected light reflected from the back surface of the conductive film 4 (the surface opposite to the substrate 1).
Note that the reflected light from the conductive film 4 becomes a problem, as described above, the EUV mask exposure region (pattern formation region), the outer (outer peripheral) region (non-pattern formation region) of the reflective layer and This is because when the absorption layer is removed by etching or the like, reflected light from a portion where the substrate is exposed without providing the reflection layer and the absorption layer becomes a problem.

  Furthermore, the EUV mask blank according to the present invention and the intermediate film 5 of the EUV mask are made of a material that satisfies the required characteristics of the conductive film 4 and the intermediate film 5 that have a light transmittance of 10% or more at a wavelength of 400 to 800 nm. Is required.

Since the EUV mask blank and the intermediate film 5 of the EUV mask according to the present invention exhibit insulating properties by containing oxygen (O) as will be described later, the film on the back side of the substrate 1, that is, the intermediate film 5 is electrically conductive. The sheet resistance value of the two films combined with the film 4 is substantially equal to the sheet resistance value of the conductive film 4. Therefore, the sheet resistance value of the film on the back side of the substrate 1 can be controlled by the sheet resistance value of the conductive film 4.
Moreover, the EUV mask blank and the intermediate film 5 of the EUV mask according to the present invention contain oxygen (O) as will be described later, so that the extinction coefficient (k) with respect to light having a wavelength of 400 to 800 nm is 1.0 or less. It becomes. Therefore, as shown also in the Example mentioned later, the light transmittance of two films | membranes which combined the intermediate film 5 and the electrically conductive film 4 with respect to the light of wavelength 400-800 nm is substantially equal to the light transmittance of the electrically conductive film 4. Value, no significant difference. Therefore, the light transmittance of 400 to 800 nm of the film on the back side of the substrate 1 can be generally controlled by the light transmittance of the conductive film 4.
As described above, since the EUV mask blank and the intermediate film 5 of the EUV mask according to the present invention have little influence on the sheet resistance value and the light transmittance of 400 to 800 nm, the intermediate film 5 has a vacuum ultraviolet region (190 to 190). The material and the film thickness can be determined so that the light reflectance of 400 nm) becomes a desired value.

  In order to achieve the above required characteristics, an embodiment of the EUV mask blank and EUV mask intermediate film 5 according to the present invention includes at least one selected from the group consisting of chromium (Cr) and tantalum (Ta), and oxygen (O And). Hereinafter, the intermediate film of this embodiment is referred to as an intermediate film (Cr, Ta: O). Specific examples of the 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 70 at%, and the content of oxygen (O) is 30 to 90 at%.
If the intermediate film (Cr, Ta: O) has the above composition, the function of suppressing the reflected light in the vacuum ultraviolet region (190 to 400 nm) from the conductive film 4 is sufficient, and the film thickness of the intermediate film 5 is adjusted. Therefore, the reflectance with respect to light in the vacuum ultraviolet region becomes 20% or less.
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 sputtering film formation, and abnormal discharge occurs, so that stable film formation becomes difficult. There's a problem.
If the total content of Cr and Ta in the intermediate film (Cr, Ta: O) exceeds 70 at%, the function of suppressing the reflected light in the vacuum ultraviolet region from the conductive film 4 becomes insufficient, and the light in the vacuum ultraviolet region is not affected. The reflectance does not fall below 20%.
When the content of O in the intermediate film (Cr, Ta: O) is less than 30 at%, the function of suppressing the reflected light in the vacuum ultraviolet region from the conductive film 4 becomes insufficient, and the reflectance for light in the vacuum ultraviolet region is low. It will not be less than 20%.
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) has a total content of Cr and Ta of preferably 15 to 70 at%, more preferably 20 to 70 at%, and even more preferably 25 to 70 at%.
The intermediate film (Cr, Ta: O) has an O content of preferably 30 to 85 at%, more preferably 30 to 80 at%, and still more preferably 30 to 75 at%.

The intermediate film 5 of the present invention may contain components other than Cr, Ta, and O as optional components as long as the above-described required characteristics are not impaired. Specific examples of such an optional component include nitrogen (N), hydrogen (H), boron (B), silicon (Si), and hafnium (Hf). Any of these optional components has a small influence on the light transmittance at a wavelength of 400 to 800 nm. N, H, and B have a small influence on the reflectance with respect to light in the vacuum ultraviolet region. Si and Hf may exhibit an effect of suppressing reflected light in the vacuum ultraviolet region.
However, the total content of these optional components may be 27 at% or less, preferably 20 at% or less, more preferably 18 at% or less, and further preferably 15 at% or less.
In addition, also in the case of the intermediate film 5, it is preferable not to contain Al and In with a high light absorption coefficient with respect to the light with a wavelength of 400-800 nm. When the total content of Al and In is 5 at% or less in the intermediate film 5 of the present invention, the light absorption in the intermediate film 5 is reduced, and the light transmittance at a wavelength of 400 to 800 nm is 10% or more. Is preferable. The total content of Al and In is preferably 3 at% or less, more preferably 1 at% or less, and still more preferably substantially not contained.

It is considered that the smoothness of the intermediate film surface is further improved by containing N among the above optional components. When the smoothness of the surface of the intermediate film is improved, it is expected that the smoothness of the surface of the conductive film 4 formed on the intermediate film is also improved.
The intermediate film containing N contains at least one selected from the group consisting of Cr and Ta, and O and N.
Hereinafter, the intermediate film of this embodiment is referred to as an intermediate film (Cr, Ta: ON). Specific examples of the intermediate film (Cr, Ta: ON) include a CrON film, a TaON film, and a CrTaON film.

The intermediate film (Cr, Ta: ON) may have a total content of Cr and Ta of 10 to 70 at% and a total content of O and N of 30 to 90 at%. The composition ratio of O and N, O: N, is less than 10: more than 0 to 7: 3.
If the intermediate film (Cr, Ta: ON) has the above composition, the function of suppressing the reflected light in the vacuum ultraviolet region (190 to 400 nm) from the conductive film 4 is sufficient, and the film thickness of the intermediate film 5 is adjusted. Therefore, the reflectance with respect to light in the vacuum ultraviolet region becomes 20% or less.
If the total content of Cr and Ta in the intermediate film (Cr, Ta: ON) is less than 10 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.
If the total content of Cr and Ta in the intermediate film (Cr, Ta: ON) is more than 70 at%, the function of suppressing the reflected light in the vacuum ultraviolet region from the conductive film 4 becomes insufficient, and the light in the vacuum ultraviolet region is affected. The reflectance does not fall below 20%.
If the content of O and N in the intermediate film (Cr, Ta: ON) is less than 30 at%, the function of suppressing the reflected light in the vacuum ultraviolet region from the conductive film 4 is insufficient, and the reflection to the light in the vacuum ultraviolet region is insufficient. The rate is not less than 20%.
If the O and N content in the intermediate film (Cr, Ta: ON) exceeds 90 at%, the discharge becomes unstable during sputtering film formation and abnormal discharge occurs, making it difficult to form a stable film. There is.
When O of the intermediate film (Cr, Ta: ON) is lower than the above composition ratio, the function of suppressing the reflected light in the vacuum ultraviolet region from the conductive film 4 is insufficient, and the reflectance for the light in the vacuum ultraviolet region is 20%. It may not be the following.

The intermediate film (Cr, Ta: ON) has a total content of Cr and Ta of preferably 15 to 70 at%, more preferably 20 to 70 at%, and even more preferably 25 to 70 at%.
In the intermediate film (Cr, Ta: ON), the total content of O and N is preferably 30 to 85 at%, more preferably 30 to 80 at%, and further preferably 30 to 75 at%.

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 described above, excellent smoothness on the surface of the conductive film is preferable from the viewpoint of preventing film peeling during electrostatic chucking. When the smoothness of the intermediate film surface is improved, the surface smoothness of the conductive film formed on the intermediate film is also expected to be 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 4 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 total film thickness of the intermediate film 5 and the conductive film 4 is not less than 17 nm and less than 50 nm. As described above, in order to obtain sufficient conductivity as the back surface conductive film, the conductive film 4 needs to have a film thickness of 2 nm or more. Therefore, the total film thickness of the conductive film 4 and the intermediate film 5 is less than 17 nm. Then, since the film thickness of the intermediate film 5 becomes too small, the function of sufficiently suppressing the reflection in the vacuum ultraviolet region (190 to 400 nm) from the conductive film 4 side becomes insufficient, and the reflectance in the vacuum ultraviolet region is 20%. It will not be below.
On the other hand, if the total film thickness of the conductive film 4 and the intermediate film 5 is 50 nm or more, the increase in the film thickness no longer contributes to improving the functions of the conductive film 4 and the intermediate film 5. There is a problem that the time required for the formation increases and the cost required for forming the conductive film 4 and the intermediate film 5 increases.
The total film thickness of the conductive film 4 and the intermediate film 5 is preferably 19 nm or more and less than 50 nm, and more preferably 22 nm or more and less than 50 nm.
The film thickness of the intermediate film 5 is 10 nm or more and less than 48 nm, preferably 15 nm or more and less than 48 nm, more preferably 17 nm or more and less than 48 nm, and still more preferably 20 nm or more and less than 48 nm.

The procedure for forming the intermediate film 5 is shown below.
When the intermediate film 5 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 5 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 5 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 5 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 5 by the above-described method, specifically, it may be performed under the following film forming conditions.
CrO film, if <br/> sputtering gas to form a TaO film: 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
When forming a CrON film or a TaON film Sputtering gas: Mixed gas of Ar, O ₂ and N ₂ (O ₂ gas concentration: 5 to 80 vol%, N ₂ gas concentration: 5 to 75 vol%, 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~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 Ar 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 EUV mask blank of the present invention may have the configuration shown in FIG. 1, that is, the configuration other than the substrate 1, the reflective layer 2, the absorption layer 3, the conductive film (back conductive film) 4, and the intermediate film 5. Good.

In the EUV mask blank of the present invention, a protective layer may be formed between the reflective layer 2 and the absorbing layer 3. The protective layer protects the reflective layer 2 so that the reflective layer 2 is not damaged by etching when the absorbent layer 3 is etched (usually dry etching) to form a mask pattern on the absorbent layer 3. It is provided for the purpose. Therefore, as the material of the protective layer, a material that is not easily affected by the etching of the absorbing layer 3, that is, the etching rate is slower than that of the absorbing layer 3 and is not easily damaged by the etching is selected. Examples of the material satisfying this condition include Cr, Al, Ta and nitrides thereof, Ru and Ru compounds (RuB, RuSi, etc.), and SiO ₂ , Si ₃ N ₄ , Al ₂ O ₃ and mixtures thereof. Is done. Among these, Ru and Ru compounds (RuB, RuSi, etc.), CrN and SiO ₂ are preferable, and Ru and Ru compounds (RuB, RuSi, etc.) are particularly preferable.
Moreover, when forming a protective layer, the thickness is preferably 1 to 60 nm, and more preferably 1 to 40 nm.

When forming a protective layer, it forms into a film using well-known film-forming methods, such as a magnetron sputtering method and an ion beam sputtering method. When a Ru film is formed by magnetron sputtering, a Ru target is used as a target, and Ar gas (gas pressure: 1.0 × 10 ⁻² Pa to 10 × 10 ⁻¹ Pa) is used as a sputtering gas. It is preferable to form a film at a thickness of 2 to 5 nm at ˜1500 W and a film formation rate of 1.2 to 60 nm / min.

  Even when a protective layer is provided on the reflective layer 2, the maximum value of the light reflectance near the wavelength of 13.5 nm is preferably 60% or more, more preferably 63% or more, and 65% or more. Further preferred.

Furthermore, in the EUV mask blank of the present invention, a low reflection layer for inspection light used for inspection of the mask pattern may be formed on the absorption layer 3.
The low reflection layer is formed of a film that exhibits low reflection in the inspection light used for inspection of the mask pattern. When producing an EUV mask, after forming a pattern in the absorption layer, it is inspected whether this pattern is formed as designed. In this mask pattern inspection, an inspection machine that normally uses light of about 257 nm as inspection light is used. That is, the difference in reflectance of light of about 257 nm, specifically, the reflectance between the surface exposed by removing the absorption layer by pattern formation and the surface of the absorption layer remaining without removal by pattern formation. Inspected by difference. Here, the former is a reflective layer surface or a protective layer surface, and is usually a protective layer surface. Therefore, if the difference in reflectance between the reflection layer surface or the protective layer surface and the absorption layer surface with respect to the wavelength of the inspection light is small, the contrast at the time of inspection deteriorates and accurate inspection cannot be performed. When the difference in reflectance between the reflection layer surface or the protective layer surface and the absorption layer surface with respect to the wavelength of the inspection light is small, the contrast at the time of inspection is improved by forming the low reflection layer. When a low reflection layer is formed on the absorption layer, the low reflection layer has a maximum reflectance of a wavelength of 15% or less when the surface of the low reflection layer is irradiated with light in the wavelength region of the inspection light. Is preferably 10% or less, more preferably 5% or less.

In order to achieve the above characteristics, the low reflection layer is preferably made of a material whose refractive index at the wavelength of the inspection light is lower than that of the absorption layer.
The low reflection layer satisfying this characteristic includes at least one selected from the group consisting of tantalum (Ta), palladium (Pd), chromium (Cr), silicon (Si), and hafnium (Hf), oxygen (O), and nitrogen. And at least one selected from the group consisting of (N). Preferable examples of such a low reflection layer include TaPdO layer, TaPdON layer, TaON layer, CrO layer, CrON layer, SiON layer, SiN layer, HfO layer, and HfON layer.
The total content of Ta, Pd, Cr, Si, and Hf in the low reflection layer is preferably 10 to 55 at%, particularly 10 to 50 at%, because the optical characteristics with respect to the wavelength region of the pattern inspection light can be controlled. .
Further, it is preferable that the total content of O and N in the low reflection layer is 45 to 90 at%, particularly 50 to 90 at%, because the optical characteristics with respect to the wavelength region of the pattern inspection light can be controlled. The total content of Ta, Pd, Cr, Si, Hf, O and N in the low reflective layer is preferably 95 to 100 at%, more preferably 97 to 100 at%, and further preferably 99 to 100 at%.

The low reflection layer having the above-described configuration can be formed by performing a sputtering method using a target containing at least one of Ta, Pd, Cr, Si, and Hf. Here, as the target, any of the above-described two or more kinds of metal targets and compound targets can be used.
The use of two or more types of metal targets is convenient for adjusting the constituent components of the low reflection layer. In addition, when using 2 or more types of metal targets, the structural component of an absorption layer can be adjusted by adjusting the input electric power to a target. On the other hand, when using a compound target, it is preferable to adjust the target composition in advance so that the formed low reflection layer has a desired composition.

The sputtering method using the above target can be carried out in an inert gas atmosphere in the same manner as the sputtering method for forming the absorption layer.
However, when the low reflection layer contains O, the sputtering method is performed in an inert gas atmosphere containing at least one of He, Ar, Ne, Kr, and Xe and O ₂ . When the low reflective layer contains N, the sputtering method is performed in an inert gas atmosphere containing at least one of He, Ar, Ne, Kr, and Xe and N ₂ . When the low reflective layer contains O and N, the sputtering method is performed in an inert gas atmosphere containing at least one of He, Ar, Ne, Kr and Xe, and O ₂ and N ₂ .

Specific conditions for performing the sputtering method vary depending on the target to be used and the composition of the inert gas atmosphere in which the sputtering method is performed. In any case, the sputtering method may be performed under the following conditions.
The conditions for forming the low reflective layer are shown below, taking as an example the case where the inert gas atmosphere is a mixed gas atmosphere of Ar and O ₂ .
Forming conditions <br/> gas pressure of the low reflective ^{layer: 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.
Sputtering gas: Ar and O ₂ mixed gas (O ₂ gas concentration: 3 to 80 vol%, preferably 5 to 60 vol%, more preferably 10 to 40 vol%)
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 using an inert gas other than Ar or a plurality of inert gases, the total concentration of the inert gas is set to the same concentration range as the Ar gas concentration described above. Further, the inert gas atmosphere when containing N ₂ if N ₂ concentration, inert gas atmosphere containing N ₂ and O _2, the same concentration range as the oxygen concentrations above the total concentration.

  In the EUV mask blank of the present invention, the low reflection layer is preferably formed on the absorption layer because the wavelength of the pattern inspection light and the wavelength of the EUV light are different. Therefore, when EUV light (near 13.5 nm) is used as pattern inspection light, it is considered unnecessary to form a low reflection layer on the absorption layer. The wavelength of the inspection light tends to shift to the short wavelength side as the pattern size becomes smaller, and it is conceivable that it will shift to 193 nm and further to 13.5 nm in the future. When the wavelength of the inspection light is 13.5 nm, it is considered unnecessary to form a low reflection layer on the absorption layer.

  In the EUV mask blank of the present invention, on the absorption layer (when the low reflection layer is formed on the absorption layer, on the absorption layer), it is described in JP2009-54899A or JP2009-21582A. A hard mask layer, that is, a layer of a material resistant to the etching conditions of the absorption layer (or the absorption layer and the low reflection layer when the low reflection layer is formed on the absorption layer) may be formed. . By forming such a hard mask layer, the absorption layer (the low reflection layer is formed on the absorption layer) under the etching conditions of the absorption layer (the absorption layer and the low reflection layer when the low reflection layer is formed on the absorption layer) is formed. If formed, the etching selectivity between the absorption layer and the low reflection layer) and the hard mask layer, specifically, the absorption layer (if the low reflection layer is formed on the absorption layer, the absorption layer and the low reflection layer) The ratio of the etching rate of the absorption layer under the etching conditions of the layer) (the etching rate of the absorption layer and the low reflection layer when a low reflection layer is formed on the absorption layer) and the etching rate of the hard mask layer By increasing the thickness, the resist can be thinned.

The present invention will be further described below using examples.
(Examples 1-15)
Examples 1 to 15 shown below are reference examples in which the intermediate film 5 is not formed between the substrate 1 and the conductive film 4. The intermediate film 5 is formed on one surface side of the substrate 1 (without forming the intermediate film 5. ) When the conductive film 4 is formed, the sheet resistance value of the conductive film 4 and the light transmittance with respect to light having a wavelength of 400 to 800 nm are evaluated.
That is, as described above, the EUV mask blank and the EUV mask intermediate film 5 according to the present invention contain oxygen (O), thereby exhibiting insulating properties and an extinction coefficient for light having a wavelength of 400 to 800 nm ( Since k) is 1.0 or less, the intermediate film 5 and the conductive film are evaluated by evaluating the sheet resistance value and the light transmittance at a wavelength of 400 to 800 nm in the embodiment in which only the conductive film 4 is formed as in Examples 1 to 15. It can be referred to as an evaluation of the sheet resistance value of the two films combined with the film 4 and the light transmittance at a wavelength of 400 to 800 nm.
Example 1
In this example, the conductive film 4 is formed on one surface side of the substrate 1 (without forming the intermediate film 5).
As the substrate 1 for film formation, a SiO ₂ —TiO ₂ glass substrate (outer diameter 6 inches (152 mm) square, thickness 6.3 mm) is used. This glass substrate has a thermal expansion coefficient at 20 ° C. of 0.05 × 10 ⁻⁷ / ° C., Young's modulus of 67 GPa, Poisson's ratio of 0.17, and specific rigidity of 3.07 × 10 ⁷ m ² / s ² . This glass substrate is polished to form a smooth surface with a surface roughness (rms) of 0.15 nm or less and a flatness of 100 nm or less.

A CrN film is formed as the conductive film 4 on one surface side of the substrate 1 by using a magnetron sputtering method. The conditions for forming the conductive film 4 (CrN film) are as follows.
Target: Cr target Sputtering gas: mixed gas of Ar and _{N 2 (Ar: 80vol%,} N 2: 20vol%, gas pressure: 0.3 Pa)
Input power: 150W
Deposition rate: 6.1 nm / min
Film thickness: 13nm
Composition analysis of the conductive film 4 (CrN film) The composition of the conductive film 4 (CrN film) was measured using an X-ray photoelectron spectrometer. The composition ratio (at%) of the conductive film 4 (CrN film) is Cr: N = 77: 23.
The relationship between the nitrogen content C in the conductive film 4 and the film thickness t is as follows.
0.15 × 23 + 1.68 (= 5.13) ≦ 13 ≦ 0.31 × 23 + 11.13 (= 18.26)
The sheet resistance value of the conductive film 4 was measured using a four-probe measuring instrument. The sheet resistance value was 112Ω / □.
Moreover, as a result of measuring the light transmittance of the conductive film 4 having a wavelength of 400 to 800 nm using a spectrophotometer, the light transmittance is 10% or more in any wavelength region, and in particular, the light transmittance of a wavelength of 532 nm is It was 21.5%.

Example 2
Example 1 is the same as Example 1 except that the conditions for forming the conductive film 4 (CrN film) are as follows.
Target: Cr target sputtering gas: mixed gas of Ar and N ₂ (Ar: 73 vol%, N ₂ : 27 vol%, gas pressure: 0.3 Pa)
Input power: 150W
Deposition rate: 5.9 nm / min
Film thickness: 20nm
Composition analysis of conductive film 4 (CrN film) The composition of conductive film 4 (CrN film) was measured in the same procedure as in Example 1. The composition ratio (at%) of the conductive film 4 (CrN film) is Cr: N = 69: 31.
The relationship between the nitrogen content C in the conductive film 4 and the film thickness t is as follows.
0.15 × 31 + 1.68 (= 6.33) ≦ 20 ≦ 0.31 × 31 + 11.13 (= 20.74)
The sheet resistance value of the conductive film 4 was 73Ω / □.
In any wavelength region of wavelengths 400 to 800 nm, the light transmittance was 10% or more, and in particular, the light transmittance at a wavelength of 532 nm was 11.5%.

Example 3
The same as Example 2 except that the film thickness of the conductive film 4 (CrN film) was 8 nm.
The composition of the conductive film 4 (CrN film) was measured in the same procedure as in Example 1. The composition ratio (at%) of the conductive film 4 (CrN film) is Cr: N = 69: 31.
The relationship between the nitrogen content C in the conductive film 4 and the film thickness t is as follows.
0.15 × 31 + 1.68 (= 6.33) ≦ 8 ≦ 0.31 × 31 + 11.13 (= 20.74)
The sheet resistance value of the conductive film 4 was 203Ω / □.
In any wavelength region of wavelengths 400 to 800 nm, the light transmittance was 10% or more, and in particular, the light transmittance at a wavelength of 532 nm was 29.4%.

Example 4
Example 1 is the same as Example 1 except that the conditions for forming the conductive film 4 (CrN film) are as follows.
Target: Cr target Sputtering gas: Mixed gas of Ar and N ₂ (Ar: 95 vol%, N ₂ : 5 vol%, gas pressure: 0.3 Pa)
Input power: 150W
Deposition rate: 6.6 nm / min
Film thickness: 12nm
Composition Analysis of Conductive Film 4 (CrN Film) The composition of the conductive film 4 (CrN film) is measured by the same procedure as in Example 1. The composition ratio (at%) of the conductive film 4 (CrN film) is Cr: N = 95: 5.
The relationship between the nitrogen content C in the conductive film 4 and the film thickness t is as follows.
0.15 × 5 + 1.68 (= 2.43) ≦ 12 ≦ 0.31 × 5 + 11.13 (= 12.68)
The sheet resistance value of the conductive film 4 is 50Ω / □.
In any wavelength region of wavelengths 400 to 800 nm, the light transmittance is 10% or more, and in particular, the light transmittance at a wavelength of 532 nm is 11.9%.

Example 5
The same as Example 4 except that the film thickness of the conductive film 4 (CrN film) is 4 nm.
Composition analysis of the conductive film 4 (CrN film) The composition of the conductive film 4 (CrN film) is measured using an X-ray photoelectron spectrometer. The composition ratio (at%) of the conductive film 4 (CrN film) is Cr: N = 95: 5.
The relationship between the nitrogen content C in the conductive film 4 and the film thickness t is as follows.
0.15 × 5 + 1.68 (= 2.43) ≦ 4 ≦ 0.31 × 5 + 11.13 (= 12.68)
The sheet resistance value of the conductive film 4 is 150Ω / □.
In any wavelength region of wavelengths from 400 to 800 nm, the light transmittance is 10% or more, and in particular, the light transmittance at a wavelength of 532 nm is 25.8%.

Example 6
Example 1 is the same as Example 1 except that the conditions for forming the conductive film 4 (CrN film) are as follows.
Target: Cr target Sputtering gas: Mixed gas of Ar and N ₂ (Ar: 64 vol%, N ₂ : 36 vol%, gas pressure: 0.3 Pa)
Input power: 150W
Deposition rate: 5.6 nm / min
Film thickness: 23nm
Composition Analysis of Conductive Film 4 (CrN Film) The composition of the conductive film 4 (CrN film) is measured by the same procedure as in Example 1. The composition ratio (at%) of the conductive film 4 (CrN film) is Cr: N = 60: 40.
The relationship between the nitrogen content C in the conductive film 4 and the film thickness t is as follows.
0.15 × 40 + 1.68 (= 7.68) ≦ 23 ≦ 0.31 × 40 + 11.13 (= 23.53)
The sheet resistance value of the conductive film 4 is 87Ω / □.
In any wavelength region of wavelengths from 400 to 800 nm, the light transmittance is 10% or more, and in particular, the light transmittance at a wavelength of 532 nm is 10.5%.

Example 7
The same as Example 6 except that the thickness of the conductive film 4 (CrN film) is 9 nm.
The composition of the conductive film 4 (CrN film) is measured by the same procedure as in Example 1. The composition ratio (at%) of the conductive film 4 (CrN film) is Cr: N = 60: 40.
The relationship between the nitrogen content C in the conductive film 4 and the film thickness t is as follows.
0.15 × 40 + 1.68 (= 7.68) ≦ 9 ≦ 0.31 × 40 + 11.13 (= 23.53)
The sheet resistance value of the conductive film 4 is 222Ω / □.
In any wavelength region of wavelengths from 400 to 800 nm, the light transmittance is 10% or more, and in particular, the light transmittance at a wavelength of 532 nm is 30.7%.

Example 8
The same as Example 4 except that the film thickness of the conductive film 4 (CrN film) is 14 nm.
Composition Analysis of Conductive Film 4 (CrN Film) The composition of the conductive film 4 (CrN film) is measured by the same procedure as in Example 1. The composition ratio (at%) of the conductive film 4 (CrN film) is Cr: N = 95: 5.
The relationship between the nitrogen content C in the conductive film 4 and the film thickness t is as follows.
0.15 × 5 + 1.68 (= 2.43) ≦ 14> 0.31 × 5 + 11.13 (= 12.68)
The sheet resistance value of the conductive film 4 is 43Ω / □.
In any wavelength region of wavelengths from 400 to 800 nm, the light transmittance is less than 10%, and in particular, the light transmittance at a wavelength of 532 nm is 8.5%.

Example 9
The same as Example 4 except that the film thickness of the conductive film 4 (CrN film) is 2 nm.
Composition Analysis of Conductive Film 4 (CrN Film) The composition of the conductive film 4 (CrN film) is measured by the same procedure as in Example 1. The composition ratio (at%) of the conductive film 4 (CrN film) is Cr: N = 95: 5.
The relationship between the nitrogen content C in the conductive film 4 and the film thickness t is as follows.
0.15 × 5 + 1.68 (= 2.43)> 2 ≦ 0.31 × 5 + 11.13 (= 12.68)
The sheet resistance value of the conductive film 4 is 300Ω / □.
In any wavelength region of wavelengths 400 to 800 nm, the light transmittance is 10% or more, and in particular, the light transmittance at a wavelength of 532 nm is 29.2%.

Example 10
The same as Example 1 except that the film thickness of the conductive film 4 (CrN film) was 20 nm.
Composition analysis of conductive film 4 (CrN film) The composition of conductive film 4 (CrN film) was measured in the same procedure as in Example 1. The composition ratio (at%) of the conductive film 4 (CrN film) was Cr: N = 77: 23.
The relationship between the nitrogen content C in the conductive film 4 and the film thickness t is as follows.
0.15 × 23 + 1.68 (= 5.13) ≦ 20> 0.31 × 23 + 11.13 (= 18.26)
The sheet resistance value of the conductive film 4 was 68Ω / □.
In any wavelength region of wavelengths 400 to 800 nm, the light transmittance was less than 10%, and in particular, the light transmittance at a wavelength of 532 nm was 7.8%.

Example 11
The same as Example 1 except that the film thickness of the conductive film 4 (CrN film) was 4 nm.
Composition Analysis of Conductive Film 4 (CrN Film) The composition of the conductive film 4 (CrN film) is measured by the same procedure as in Example 1. The composition ratio (at%) of the conductive film 4 (CrN film) is Cr: N = 77: 23.
The relationship between the nitrogen content C in the conductive film 4 and the film thickness t is as follows.
0.15 × 23 + 1.68 (= 5.13)> 4 ≦ 0.31 × 23 + 11.13 (= 18.26)
The sheet resistance value of the conductive film 4 is 330Ω / □.
In any wavelength region of wavelengths from 400 to 800 nm, the light transmittance is 10% or more, and in particular, the light transmittance at a wavelength of 532 nm is 32%.

Example 12
The same as Example 6 except that the film thickness of the conductive film 4 (CrN film) is 25 nm.
The composition of the conductive film 4 (CrN film) is measured by the same procedure as in Example 1. The composition ratio (at%) of the conductive film 4 (CrN film) is Cr: N = 60: 40.
The relationship between the nitrogen content C in the conductive film 4 and the film thickness t is as follows.
0.15 × 40 + 1.68 (= 7.68) ≦ 25> 0.31 × 40 + 11.13 (= 23.53)
The sheet resistance value of the conductive film 4 is 80Ω / □.
In any wavelength region of wavelengths from 400 to 800 nm, the light transmittance is less than 10%, and in particular, the light transmittance at a wavelength of 532 nm is 7.6%.

Example 13
The same as Example 6 except that the film thickness of the conductive film 4 (CrN film) is 6 nm.
The composition of the conductive film 4 (CrN film) is measured by the same procedure as in Example 1. The composition ratio (at%) of the conductive film 4 (CrN film) is Cr: N = 60: 40.
The relationship between the nitrogen content C in the conductive film 4 and the film thickness t is as follows.
0.15 × 40 + 1.68 (= 7.68)> 6 ≦ 0.31 × 40 + 11.13 (= 23.53)
The sheet resistance value of the conductive film 4 is 333Ω / □.
In any wavelength region of wavelengths from 400 to 800 nm, the light transmittance is 10% or more, and in particular, the light transmittance at a wavelength of 532 nm is 35%.

Example 14
Example 1 is the same as Example 1 except that the conditions for forming the conductive film 4 (CrN film) are as follows.
Target: Cr target Sputtering gas: Mixed gas of Ar and N ₂ (Ar: 55 vol%, N ₂ : 45 vol%, gas pressure: 0.3 Pa)
Input power: 150W
Deposition rate: 5.0 nm / min
Film thickness: 15nm
Composition Analysis of Conductive Film 4 (CrN Film) The composition of the conductive film 4 (CrN film) is measured by the same procedure as in Example 1. The composition ratio (at%) of the conductive film 4 (CrN film) is Cr: N = 57: 43.
The relationship between the nitrogen content C in the conductive film 4 and the film thickness t is as follows.
0.15 × 43 + 1.68 (= 8.13) ≦ 15 ≦ 0.31 × 43 + 11.13 (= 24.46)
The sheet resistance value of the conductive film 4 is 1312Ω / □.
In any wavelength region of wavelengths from 400 to 800 nm, the light transmittance is 10% or more, and in particular, the light transmittance at a wavelength of 532 nm is 22.7%.

Example 15
Example 1 is the same as Example 1 except that the conditions for forming the conductive film 4 are as follows.
Target: Cr target Sputtering gas: Ar gas (gas pressure: 0.3 Pa)
Input power: 150W
Deposition rate: 7.2 nm / min
Film thickness: 5nm
Composition Analysis of Conductive Film 4 (CrN Film) The composition of the conductive film 4 is measured in the same procedure as in Example 1. The conductive film 4 is a Cr film with 100 at% Cr.
The relationship between the nitrogen content C in the conductive film 4 and the film thickness t is as follows.
0.15 × 0 + 1.68 (= 1.68) ≦ 5 ≦ 0.31 × 0 + 11.13 (= 11.13)
The sheet resistance value of the conductive film 4 is 80Ω / □.
In any wavelength region of wavelengths from 400 to 800 nm, the light transmittance is 10% or more, and in particular, the light transmittance at a wavelength of 532 nm is 22.7%.
Moreover, when the adhesiveness of the conductive film 4 is evaluated from the conductive film 4 based on JIS K5400 (cross-cut method), film peeling is confirmed and the adhesiveness is insufficient.
On the other hand, about Example 1-14, film peeling is not confirmed but adhesiveness is enough.

FIG. 2 is a graph showing the relationship between the nitrogen content (C) in the conductive film and the film thickness of the back conductive film in Examples 1 to 15. In FIG. 2, the case where the sheet resistance value is 250Ω / □ is indicated by a thin line. This corresponds to t = 0.15C + 1.68. The case where the light transmittance at a wavelength of 532 nm is 10% is indicated by a bold line. This corresponds to t = 0.31C + 11.13.
In all the examples (Examples 1 to 7), the sheet resistance value was 250Ω / □ or less, and the light transmittance at a wavelength of 532 nm was 10% or more.
In Examples 8, 10, and 12 where t> 0.31C + 11.13, the light transmittance at a wavelength of 532 nm is less than 10%.
In Examples 9, 11, and 13 where t <0.15C + 1.68, the sheet resistance value is more than 250Ω / □.
In Example 14 in which the N content in the conductive film exceeds 42 at%, the sheet resistance value exceeds 250 Ω / □.
In Example 15 in which the N content in the conductive film was 0 at%, when the adhesion was evaluated based on JIS K5400 (cross-cut method), film peeling was confirmed, and the adhesion was insufficient.
For Examples 1 to 14, adhesion is evaluated, but film peeling is not confirmed, and adhesion is sufficient.

(Examples 16 and 17)
Examples 16 and 17 are examples. In each of Examples 16 and 17, the sheet resistance value of the conductive film 4 and the light transmission of the conductive film 4 and the intermediate film 5 when the intermediate film 5 and the conductive film 4 are formed on one surface side of the substrate 1. The present invention includes an EUV mask blank and an EUV mask including the reflective layer 2 and the absorption layer 3, and further includes a protective layer, a low reflection layer, and the like in addition to the reflective layer 2 and the absorption layer 3. Of EUV mask blanks and EUV masks.
Example 16
In this example, the intermediate film 5 and the conductive film 4 were formed on one surface side of the substrate 1.
A CrO film was formed as an intermediate film 5 on one surface side of the substrate 1 similar to Example 1 using a magnetron sputtering method. The conditions for forming the intermediate film 5 (CrO film) are as follows.
Target: Cr target sputtering gas: mixed gas of Ar and O ₂ (gas flow rate (O ₂ / Ar): 20/35 (sccm), gas pressure: 0.3 Pa)
Input power: 150W
Deposition rate: 9.0 nm / min
Film thickness: 14nm
Composition analysis of intermediate film 5 (CrO film) The composition of the intermediate film 5 (CrO film) is measured using an X-ray photoelectron spectrometer. The composition ratio (at%) of the intermediate film 5 (CrO film) is Cr: O = 58: 42.

Next, a CrN film was formed as the conductive film 4 on the intermediate film 5 by using a magnetron sputtering method. The conditions for forming the conductive film 4 (CrN film) are as follows.
Target: Cr target Sputtering gas: Mixed gas of Ar and N ₂ (gas flow rate (N ₂ / Ar): 10/45 (sccm), gas pressure: 0.3 Pa)
Input power: 150W
Deposition rate: 6.1 nm / min
Film thickness: 14nm
Composition analysis of the conductive film 4 (CrN film) The composition of the conductive film 4 (CrN film) is measured using an X-ray photoelectron spectrometer. The composition ratio (at%) of the conductive film 4 (CrN film) is Cr: N = 77: 23.
The relationship between the nitrogen content C in the conductive film 4 and the film thickness t is as follows.
0.15 × 23 + 1.68 (= 5.13) ≦ 14 ≦ 0.31 × 23 + 11.13 (= 18.26)
The total film thickness of the conductive film 4 and the intermediate film 5 was 28 nm.
The sheet resistance value of the conductive film 4 was measured using a four-probe measuring instrument. The sheet resistance value was 113Ω / □.
Moreover, the light transmittance of wavelength 400-800 nm when a light ray injects from the conductive film 4 side was measured using the spectrophotometer. The light transmittance was 10% or more in any wavelength range of 400 to 800 nm. The light transmittances at wavelengths of 400 nm, 532 nm, and 800 nm are as follows.
Wavelength 400 nm: 15.8%
Wavelength 532 nm: 16.8%
Wavelength 800 nm: 18.3%
Further, when a light beam is incident from the surface of the substrate 1 on the side where the conductive film 4 and the intermediate film 5 are not formed, the light reflectance at a wavelength of 190 to 400 nm from the conductive film 4 side is used using a spectrophotometer. Measured. The reflectance for light in the vacuum ultraviolet region (190 to 400 nm) is 20% or less, and by providing the intermediate film 5, the reflectance is 20% or less for all wavelengths of 190 to 400 nm. It was possible.
The light transmittance and light reflectance at wavelengths of 190 to 800 nm are shown in FIG.
Moreover, the sheet resistance value of the conductive film 4 and the light transmittance of the conductive film 4 were also evaluated when the conductive film 4 was formed in the same procedure as described above without forming the intermediate film 5.
The sheet resistance value of the conductive film 4 was 112Ω / □, which was almost the same as when the intermediate film 5 was formed. FIG. 4 is a graph comparing the light transmittance at a wavelength of 400 to 800 nm with respect to Example 16 as compared with the case where no intermediate film was formed. As is apparent from this graph, there was no significant difference in the light transmittance at a wavelength of 400 to 800 nm depending on the presence or absence of the intermediate film.

Example 17
The conditions of the intermediate film (CrO film) 5 and the conductive film 4 (CrN film) were the same as in Example 16 except that the film formation conditions were as follows.
Interlayer film 5
Target: Cr target sputtering gas: mixed gas of Ar and O ₂ (gas flow rate (O ₂ / Ar): 20/35 (sccm), gas pressure: 0.3 Pa)
Input power: 150W
Deposition rate: 9.0 nm / min
Film thickness: 14nm
Conductive film 4
Target: Cr target Sputtering gas: Mixed gas of Ar and N ₂ (gas flow rate (N ₂ / Ar): 15/40 (sccm), gas pressure: 0.3 Pa)
Input power: 150W
Deposition rate: 6.6 nm / min
Film thickness: 15nm
Composition Analysis of Intermediate Film 5 (CrO Film) The composition of the intermediate film 5 (CrO film) is measured in the same procedure as in Example 16. The composition ratio (at%) of the intermediate film 5 (CrO film) is Cr: O = 58: 42.
Composition analysis of the conductive film 4 (CrN film) The composition of the conductive film 4 (CrN film) is measured in the same procedure as in Example 16. The composition ratio (at%) of the conductive film 4 (CrN film) is Cr: N = 69: 31.
The relationship between the nitrogen content C in the conductive film 4 and the film thickness t is as follows.
0.15 × 31 + 1.68 (= 6.33) ≦ 15 ≦ 0.31 × 31 + 11.13 (= 20.74)
The total film thickness of the conductive film 4 and the intermediate film 5 was 29 nm.
The sheet resistance value of the conductive film 4 was 149Ω / □.
Moreover, the light transmittance at a wavelength of 400 to 800 nm when a light beam was incident from the conductive film 4 side was 10% or more in any wavelength region of the wavelength from 400 to 800 nm. The light transmittances at wavelengths of 400 nm, 532 nm, and 800 nm are as follows.
Wavelength 400 nm: 19.0%
Wavelength 532 nm: 20.8%
Wavelength 800 nm: 22.6%
The light reflectance at a wavelength of 190 to 400 nm from the conductive film 4 side when light is incident from the surface of the substrate 1 on the side where the intermediate film 5 and the conductive film 4 are not formed is 20% or less. By providing the intermediate film 5, it was possible to reduce the reflectance to 20% or less for all wavelengths of 190 to 400 nm.
The light transmittance and light reflectance at wavelengths of 190 to 800 nm are shown in FIG.
Moreover, the sheet resistance value of the conductive film 4 and the light transmittance of the conductive film 4 were also evaluated when the conductive film 4 was formed in the same procedure as described above without forming the intermediate film 5.
The sheet resistance value of the conductive film 4 was 149Ω / □, which was the same as when the intermediate film 5 was formed. FIG. 6 is a graph comparing the light transmittance at a wavelength of 400 to 800 nm with respect to Example 17 as compared with the case where no intermediate film was formed. As is apparent from this graph, there was no significant difference in the light transmittance at a wavelength of 400 to 800 nm depending on the presence or absence of the intermediate film.

(Examples 18-25)
Examples 18 to 21 are examples, and examples 22 to 25 are comparative examples.
Example 18
The same procedure as in Example 16 was performed except that the film thicknesses of the intermediate film 5 and the conductive film 4 were set as follows.
Intermediate film 5: 28 nm
Conductive film 4: 12 nm
Total film thickness: 40 nm
Composition Analysis of Intermediate Film 5 (CrO Film) The composition of the intermediate film 5 (CrO film) is measured in the same procedure as in Example 16. The composition ratio (at%) of the intermediate film 5 (CrO film) is Cr: O = 58: 42.
Composition analysis of the conductive film 4 (CrN film) The composition of the conductive film 4 (CrN film) is measured in the same procedure as in Example 16. The composition ratio (at%) of the conductive film 4 (CrN film) is Cr: N = 77: 23.
The relationship between the nitrogen content C in the conductive film 4 and the film thickness t is as follows.
0.15 × 23 + 1.68 (= 5.13) ≦ 12 ≦ 0.31 × 23 + 11.13 (= 18.26)
The sheet resistance value of the conductive film 4 was 176Ω / □.
The light transmittance at a wavelength of 400 to 800 nm when a light beam was incident from the conductive film 4 side was 10% or more in any wavelength region of the wavelength of 400 to 800 nm. The light transmittances at wavelengths of 400 nm, 532 nm, and 800 nm are as follows.
Wavelength 400 nm: 18.9%
Wavelength 532 nm: 22.5%
Wavelength 800 nm: 25.8%
The light reflectance at a wavelength of 190 to 400 nm from the conductive film 4 side when light is incident from the surface of the substrate 1 on the side where the intermediate film 5 and the conductive film 4 are not formed is 20% or less. By providing the intermediate film 5, it was possible to reduce the reflectance to 20% or less for all wavelengths of 190 to 400 nm.
The light transmittance and light reflectance at wavelengths of 190 to 800 nm are shown in FIG.

Example 19
The same procedure as in Example 16 was performed except that the film thicknesses of the intermediate film 5 and the conductive film 4 were set as follows.
Intermediate film 5: 29 nm
Conductive film 4: 13 nm
Total film thickness: 42 nm
Composition Analysis of Intermediate Film 5 (CrO Film) The composition of the intermediate film 5 (CrO film) is measured in the same procedure as in Example 16. The composition ratio (at%) of the intermediate film 5 (CrO film) is Cr: O = 58: 42.
Composition analysis of the conductive film 4 (CrN film) The composition of the conductive film 4 (CrN film) is measured in the same procedure as in Example 16. The composition ratio (at%) of the conductive film 4 (CrN film) is Cr: N = 77: 23.
The relationship between the nitrogen content C in the conductive film 4 and the film thickness t is as follows.
0.15 × 23 + 1.68 (= 5.13) ≦ 13 ≦ 0.31 × 23 + 11.13 (= 18.26)
The sheet resistance value of the conductive film 4 was 135Ω / □.
The light transmittance at a wavelength of 400 to 800 nm when a light beam was incident from the conductive film 4 side was 10% or more in any wavelength region of the wavelength of 400 to 800 nm. The light transmittances at wavelengths of 400 nm, 532 nm, and 800 nm are as follows.
Wavelength 400 nm: 15.3%
Wavelength 532 nm: 18.5%
Wavelength 800 nm: 21.1%
The light reflectance at a wavelength of 190 to 400 nm from the conductive film 4 side when light is incident from the surface of the substrate 1 on the side where the intermediate film 5 and the conductive film 4 are not formed is 20% or less. By providing the intermediate film 5, it was possible to reduce the reflectance to 20% or less for all wavelengths of 190 to 400 nm.
The light transmittance and light reflectance at wavelengths of 190 to 800 nm are shown in FIG.

Example 20
The conditions of the intermediate film (CrO film) 5 and the conductive film 4 (CrN film) were the same as in Example 16 except that the film formation conditions were as follows.
Interlayer film 5
Target: Cr target sputtering gas: mixed gas of Ar and O ₂ (gas flow rate (O ₂ / Ar): 20/35 (sccm), gas pressure: 0.3 Pa)
Input power: 150W
Deposition rate: 9.0 nm / min
Film thickness: 28nm
Conductive film 4
Target: Cr target Sputtering gas: Mixed gas of Ar and N ₂ (gas flow rate (N ₂ / Ar): 15/40 (sccm), gas pressure: 0.3 Pa)
Input power: 150W
Deposition rate: 6.6 nm / min
Film thickness: 16nm
Composition Analysis of Intermediate Film 5 (CrO Film) The composition of the intermediate film 5 (CrO film) is measured in the same procedure as in Example 16. The composition ratio (at%) of the intermediate film 5 (CrO film) is Cr: O = 58: 42.
Composition analysis of the conductive film 4 (CrN film) The composition of the conductive film 4 (CrN film) is measured in the same procedure as in Example 16. The composition ratio (at%) of the conductive film 4 (CrN film) is Cr: N = 69: 31.
The relationship between the nitrogen content C in the conductive film 4 and the film thickness t is as follows.
0.15 × 31 + 1.68 (= 6.33) ≦ 16 ≦ 0.31 × 31 + 11.13 (= 20.74)
The total film thickness of the intermediate film 5 and the conductive film 4 was 44 nm.
The sheet resistance value of the conductive film 4 was 194Ω / □.
The light transmittance at a wavelength of 400 to 800 nm when a light beam was incident from the conductive film 4 side was 10% or more in any wavelength region of the wavelength of 400 to 800 nm. The light transmittances at wavelengths of 400 nm, 532 nm, and 800 nm are as follows.
Wavelength 400 nm: 18.1%
Wavelength 532 nm: 22.1%
Wavelength 800 nm: 25.0%
The light reflectance at a wavelength of 190 to 400 nm from the conductive film 4 side when light is incident from the surface of the substrate 1 on the side where the intermediate film 5 and the conductive film 4 are not formed is 20% or less. By providing the intermediate film 5, it was possible to reduce the reflectance to 20% or less for all wavelengths of 190 to 400 nm.
The light transmittance and light reflectance at wavelengths of 190 to 800 nm are shown in FIG.

Example 21
The same procedure as in Example 20 was performed except that the thickness of each of the intermediate film 5 and the conductive film 4 was changed to the following.
Intermediate film 5: 27 nm
Conductive film 4: 17 nm
Total film thickness: 44 nm
Composition Analysis of Intermediate Film 5 (CrO Film) The composition of the intermediate film 5 (CrO film) is measured in the same procedure as in Example 16. The composition ratio (at%) of the intermediate film 5 (CrO film) is Cr: O = Cr: O = 58: 42.
Composition analysis of the conductive film 4 (CrN film) The composition of the conductive film 4 (CrN film) is measured in the same procedure as in Example 16. The composition ratio (at%) of the conductive film 4 (CrN film) is Cr: N = 69: 31.
The relationship between the nitrogen content C in the conductive film 4 and the film thickness t is as follows.
0.15 × 31 + 1.68 (= 6.33) ≦ 17 ≦ 0.31 × 31 + 11.13 (= 20.74)
The sheet resistance value of the conductive film 4 was 157Ω / □.
The light transmittance at a wavelength of 400 to 800 nm when a light beam was incident from the conductive film 4 side was 10% or more in any wavelength region of the wavelength of 400 to 800 nm. The light transmittances at wavelengths of 400 nm, 532 nm, and 800 nm are as follows.
Wavelength 400 nm: 15.8%
Wavelength 532 nm: 19.4%
Wavelength 800 nm: 22.0%
The light reflectance at a wavelength of 190 to 400 nm from the conductive film 4 side when light is incident from the surface of the substrate 1 on the side where the intermediate film 5 and the conductive film 4 are not formed is 20% or less. By providing the intermediate film 5, it was possible to reduce the reflectance to 20% or less for all wavelengths of 190 to 400 nm.
The light transmittance and light reflectance at wavelengths of 190 to 800 nm are shown in FIG.
Example 22
The same procedure as in Example 16 was performed except that the film thicknesses of the intermediate film 5 and the conductive film 4 were set as follows.
Intermediate film 5: 5 nm
Conductive film 4: 11 nm
Total film thickness: 16nm
Composition Analysis of Intermediate Film 5 (CrO Film) The composition of the intermediate film 5 (CrO film) is measured in the same procedure as in Example 16. The composition ratio (at%) of the intermediate film 5 (CrO film) is Cr: O = 58: 42.
Composition analysis of the conductive film 4 (CrN film) The composition of the conductive film 4 (CrN film) is measured in the same procedure as in Example 16. The composition ratio (at%) of the conductive film 4 (CrN film) is Cr: N = 77: 23.
The relationship between the nitrogen content C in the conductive film 4 and the film thickness t is as follows.
0.15 × 23 + 1.68 (= 5.13) ≦ 11 ≦ 0.31 × 23 + 11.13 (= 18.26)
The sheet resistance value of the conductive film 4 was 135Ω / □.
The light transmittance at a wavelength of 400 to 800 nm when a light beam was incident from the conductive film 4 side was 10% or more in any wavelength region of the wavelength of 400 to 800 nm. The light transmittances at wavelengths of 400 nm, 532 nm, and 800 nm are as follows.
Wavelength 400 nm: 20.5%
Wavelength 532 nm: 20.5%
Wavelength 800 nm: 21.9%
In addition, when light rays are incident from the surface of the substrate 1 on the side where the intermediate film 5 and the conductive film 4 are not formed, the light reflectance at a wavelength of 190 to 400 nm from the conductive film 4 side exceeds 20%. was there.
Note that the light transmittance and light reflectance at wavelengths of 190 to 800 nm are shown in FIG.
Example 23
The same procedure as in Example 16 was performed except that the film thicknesses of the intermediate film 5 and the conductive film 4 were set as follows.
Intermediate film 5: 5 nm
Conductive film 4: 13 nm
Total film thickness: 18nm
Composition Analysis of Intermediate Film 5 (CrO Film) The composition of the intermediate film 5 (CrO film) is measured in the same procedure as in Example 16. The composition ratio (at%) of the intermediate film 5 (CrO film) is Cr: O = 58: 42.
Composition analysis of the conductive film 4 (CrN film) The composition of the conductive film 4 (CrN film) is measured in the same procedure as in Example 16. The composition ratio (at%) of the conductive film 4 (CrN film) is Cr: N = 77: 23.
The relationship between the nitrogen content C in the conductive film 4 and the film thickness t is as follows.
0.15 × 23 + 1.68 (= 5.13) ≦ 13 ≦ 0.31 × 23 + 11.13 (= 18.26)
The sheet resistance value of the conductive film 4 was 111Ω / □.
The light transmittance at a wavelength of 400 to 800 nm when a light beam was incident from the conductive film 4 side was 10% or more in any wavelength region of the wavelength of 400 to 800 nm. The light transmittances at wavelengths of 400 nm, 532 nm, and 800 nm are as follows.
Wavelength 400 nm: 16.3%
Wavelength 532 nm: 16.4%
Wavelength 800nm: 17.5%
In addition, when light rays are incident from the surface of the substrate 1 on the side where the intermediate film 5 and the conductive film 4 are not formed, the light reflectance at a wavelength of 190 to 400 nm from the conductive film 4 side exceeds 20%. was there.
The light transmittance and light reflectance at wavelengths of 190 to 800 nm are shown in FIG.
Example 24
The same procedure as in Example 16 was performed except that the film thicknesses of the intermediate film 5 and the conductive film 4 were set as follows.
Intermediate film 5: 5 nm
Conductive film 4: 14 nm
Total film thickness: 19nm
Composition Analysis of Intermediate Film 5 (CrO Film) The composition of the intermediate film 5 (CrO film) is measured in the same procedure as in Example 16. The composition ratio (at%) of the intermediate film 5 (CrO film) is Cr: O = 58: 42.
Composition analysis of the conductive film 4 (CrN film) The composition of the conductive film 4 (CrN film) is measured in the same procedure as in Example 16. The composition ratio (at%) of the conductive film 4 (CrN film) is Cr: N = 77: 23.
The relationship between the nitrogen content C in the conductive film 4 and the film thickness t is as follows.
0.15 × 23 + 1.68 (= 5.13) ≦ 14 ≦ 0.31 × 23 + 11.13 (= 18.26)
The sheet resistance value of the conductive film 4 was 134Ω / □.
The light transmittance at a wavelength of 400 to 800 nm when a light beam was incident from the conductive film 4 side was 10% or more in any wavelength region of the wavelength of 400 to 800 nm. The light transmittances at wavelengths of 400 nm, 532 nm, and 800 nm are as follows.
Wavelength 400 nm: 19.8%
Wavelength 532 nm: 20.4%
Wavelength 800 nm: 21.5%
In addition, when light rays are incident from the surface of the substrate 1 on the side where the intermediate film 5 and the conductive film 4 are not formed, the light reflectance at a wavelength of 190 to 400 nm from the conductive film 4 side exceeds 20%. was there.
The light transmittance and light reflectance at wavelengths of 190 to 800 nm are shown in FIG.
Example 25
The same procedure as in Example 17 was performed, except that the thicknesses of the conductive film 4 and the intermediate film 5 were set as follows.
Intermediate film 5: 5 nm
Conductive film 4: 16 nm
Total film thickness: 21 nm
Composition Analysis of Intermediate Film 5 (CrO Film) The composition of the intermediate film 5 (CrO film) is measured in the same procedure as in Example 16. The composition ratio (at%) of the intermediate film 5 (CrO film) is Cr: O = 58: 42.
Composition analysis of the conductive film 4 (CrN film) The composition of the conductive film 4 (CrN film) is measured in the same procedure as in Example 16. The composition ratio (at%) of the conductive film 4 (CrN film) is Cr: N = 77: 23.
The relationship between the nitrogen content C in the conductive film 4 and the film thickness t is as follows.
0.15 × 23 + 1.68 (= 5.13) ≦ 16 ≦ 0.31 × 23 + 11.13 (= 18.26)
The sheet resistance value of the conductive film 4 was 111Ω / □.
The light transmittance at a wavelength of 400 to 800 nm when a light beam was incident from the conductive film 4 side was 10% or more in any wavelength region of the wavelength of 400 to 800 nm. The light transmittances at wavelengths of 400 nm, 532 nm, and 800 nm are as follows.
Wavelength 400 nm: 16.7%
Wavelength 532 nm: 17.4%
Wavelength 800 nm: 18.3%
In addition, when the light beam is incident from the surface of the substrate 1 on the side where the conductive film 4 and the intermediate film 5 are not formed, the light reflectance at a wavelength of 190 to 400 nm from the conductive film 4 side exceeds 20%. was there.
Note that the light transmittance and light reflectance at wavelengths of 190 to 800 nm are shown in FIG.

1: Substrate 2: Reflective layer (multilayer reflective film)
3: Absorbing layer 4: (Back) conductive film 5: Intermediate film

Claims (13)

A reflective type for EUV lithography in which a reflective layer that reflects EUV light and an absorbing layer that absorbs EUV light are formed in this order on one surface side of the substrate, and a conductive film is formed on the other surface side of the substrate A mask blank,
An intermediate film is formed between the substrate and the conductive film,
The conductive film contains chromium (Cr) and nitrogen (N),
The content of Cr in the conductive film is 58 at% or more and 99 at% or less, and the content of N is 1 at% or more and 42 at% or less.
When the N content in the conductive film is C (at%) and the film thickness of the conductive film is t (nm), the following formula (1) is satisfied:
The intermediate film contains at least one selected from the group consisting of chromium (Cr) and tantalum (Ta) and oxygen (O), the total content of Cr and Ta is 10 to 70 at%, and O The EUV lithography is characterized in that the content of the intermediate film is 30 to 90 at%, the film thickness of the intermediate film is 10 nm or more and less than 48 nm, and the total film thickness of the intermediate film and the conductive film is 17 nm or more and less than 50 nm. Reflective mask blank.
0.15C + 1.68 ≦ t ≦ 0.31C + 11.13 (1)   2. The intermediate film according to claim 1, wherein the intermediate film contains at least one of nitrogen (N), hydrogen (H), boron (B), silicon (Si), and hafnium (Hf) in a total content of 27 at% or less. The reflective mask blank for EUV lithography as described.   The intermediate film contains nitrogen (N), the total content of Cr and Ta is 10 to 70 at%, the total content of O and N is 30 to 90 at%, and the composition ratio of O and N is The reflective mask blank for EUV lithography according to claim 2, wherein O: N is less than 10: more than 0 to 7: 3. The reflective mask blank for EUV lithography according to any one of claims 1 to 3 , wherein the film thickness of the conductive film is 2 nm or more and 24 nm or less. The reflective mask blank for EUV lithography according to any one of claims 1 to 4 , wherein the conductive film surface has a surface roughness (rms) of 0.5 nm or less. The reflective mask blank for EUV lithography according to any one of claims 1 to 5 , wherein a total content of aluminum (Al) and indium (In) in the conductive film is 5 at% or less. The reflective mask blank for EUV lithography according to any one of claims 1 to 6 , wherein a total content of aluminum (Al) and indium (In) in the intermediate film is 5 at% or less. The reflective mask blank for EUV lithography according to any one of claims 1 to 7 , wherein a sheet resistance value of the conductive film is 250 Ω / □ or less. The conductive film and the intermediate film, the light transmittance of the wavelength 400~800nm is 10% or more, a reflective mask blank for EUV lithography according to any one of claims 1-8. Wherein the substrate side exposed in the case of not having the reflective layer and the absorbing layer, light reflectance when irradiated with light of wavelength 190~400nm is 20% or less, according to any one of claims 1-9 Reflective mask blank for EUV lithography. A protective layer is formed between the reflective layer and the absorbing layer to protect the reflective layer when forming a pattern on the absorbing layer.
The reflective mask blank for EUV lithography according to any one of claims 1 to 10 , wherein the protective layer comprises Ru or a Ru compound as a constituent material. Claim. 1 to 11 EUV lithography reflective mask formed by patterning a reflective mask blank for EUV lithography according to any one of. The region outside the exposure region has a portion where the substrate is exposed without including the reflective layer and the absorption layer, and the light reflectance when the portion is irradiated with light having a wavelength of 190 to 400 nm is 20 The reflective mask for EUV lithography according to claim 12 , wherein the reflective mask is% or less.

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