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

Abstract

Provided is a substrate with a conductive film for manufacturing a reflective mask capable of suppressing generation of particles when an electrostatic chuck of the reflective mask is attached / detached in an exposure device, when a pattern of the reflective mask is transferred to a transfer target on a semiconductor substrate or the like using an exposure device.　A substrate with a conductive film is characterized by comprising a substrate and a conductive film formed on a first main surface of the substrate, the conductive film including a first region in which, in a Ta4f spectrum normalized by a maximum intensity value of a Ta4f peak obtained by analyzing the conductive film by X-ray photoelectron spectroscopy, a difference D between a minimum intensity value between a Ta4f5 / 2 peak and a Ta4f7 / 2 peak and an interpolation value of intensity in coupling energy of the minimum intensity value on a linear interpolation function obtained by linear interpolation on the basis of the Ta4f5 / 2 peak and the Ta4f7 / 2 peak is 0.5 or less.

Description

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

[0001] The present invention relates to a substrate with a conductive film, a substrate with a multilayer reflective film, a reflective mask blank, a reflective mask, and a method of manufacturing a semiconductor device for use in EUV lithography. The title of the invention of this application is "Substrate with Conductive Film, Substrate with Multilayer Reflective Film, Reflective Mask Blank, Reflective Mask, and Method of Manufacturing Semiconductor Device."

[0002] In recent years, the semiconductor industry has witnessed a demand for finer patterns that exceed the transfer limit of conventional photolithography using ultraviolet light, due to the increasing integration density of semiconductor devices. To enable the formation of such fine patterns, EUV lithography, an exposure technology using extreme ultraviolet (EUV) light, is considered promising. Here, EUV light refers to light in the wavelength range of the soft X-ray or vacuum ultraviolet region, specifically light with a wavelength of approximately 0.2 to 100 nm. Reflective masks have been proposed as transfer masks for use in EUV lithography. Such reflective masks have a multilayer reflective film formed on a substrate that reflects exposure light, and an absorber film that absorbs the exposure light is formed in a pattern on the multilayer reflective film.

[0003] The reflective mask is manufactured by forming an absorber pattern by lithography or the like from a reflective mask blank having a substrate, a multilayer reflective film formed on the substrate, and an absorber film formed on the multilayer reflective film.

[0004] The multilayer reflective film and the absorption layer are generally formed using a film formation method such as sputtering. During this film formation, the reflective mask blank substrate is supported by a support means in a film formation apparatus. An electrostatic chuck is used as one of the substrate support means. Furthermore, during exposure with EUV light, an electrostatic chuck is used to fix the reflective mask in the exposure apparatus. Therefore, a conductive film (back conductive film) is formed on the back surface (the surface opposite to the front surface on which the multilayer reflective film and the like are formed) of an insulating reflective mask blank substrate such as a glass substrate to facilitate fixing the substrate by the electrostatic chuck. A substrate on which a conductive film is formed is called a substrate with a conductive film.

[0005] As an example of a substrate with a conductive film, Patent Document 1 describes a mask substrate including a substrate made of a low thermal expansion material, at least one material layer on the front side of the substrate, and at least one material layer on the back side of the substrate.

[0006] Patent Document 2 describes a multilayer reflective film-coated substrate for EUV lithography, which has a glass substrate on which a multilayer reflective film that reflects EUV light is formed, and further has a conductive film formed on the surface opposite to the surface on which the multilayer reflective film is formed. Patent Document 2 describes that the conductive film is made of a material that contains tantalum and is substantially free of hydrogen, and that a hydrogen penetration suppression film is provided between the glass substrate and the conductive film to suppress penetration of hydrogen from the glass substrate into the conductive film.

[0007] Patent Document 3 describes a substrate with a multilayer reflective film, which includes a substrate and a multilayer reflective film for reflecting exposure light, the multilayer reflective film being made up of a multilayer film in which low-refractive index layers and high-refractive index layers are alternately stacked on the substrate. According to Patent Document 3, the multilayer reflective film contains at least one additive element selected from hydrogen (H), deuterium (D), and helium (He).

[0008] Japanese Patent Application Publication No. 2003-501823 Japanese Patent Application Publication No. 2013-225662 International Publication No. 2021 / 060253

[0009] A reflective mask is supported by an electrostatic chuck in an exposure apparatus when transferring a pattern onto a semiconductor substrate, for example. Since the substrate used for a reflective mask blank and a reflective mask is made of an insulating glass substrate or the like, a conductive film (rear conductive film) for the electrostatic chuck is formed on the back surface of the substrate of the reflective mask blank or the reflective mask.

[0010] During pattern transfer onto a semiconductor substrate using an exposure apparatus, misalignment of a reflective mask mounted on a movable stage using an electrostatic chuck can make high-precision pattern transfer difficult. Therefore, it is preferable that the back surface conductive film of the reflective mask be firmly fixed to the electrostatic chuck. However, if the back surface conductive film is firmly fixed to the electrostatic chuck, particles originating from the back surface film may be generated when the reflective mask is detached from the electrostatic chuck. If these particles remain on the electrostatic chuck, when the back surface conductive film of the substrate of another reflective mask is attached to the electrostatic chuck, the flatness of the reflective mask may decrease, making high-precision pattern transfer difficult. Furthermore, these particles may adhere to the reflective mask and cause defects.

[0011] Therefore, an object of the present invention is to provide a substrate with a conductive film, a substrate with a multilayer reflective film, and a reflective mask blank for manufacturing a reflective mask that can suppress the generation of particles when the reflective mask is electrostatically chucked or detached within an exposure apparatus when the pattern of the reflective mask is transferred to a target on a semiconductor substrate or the like using an exposure apparatus.

[0012] Another object of the present invention is to provide a reflective mask that can suppress the generation of particles when the reflective mask is electrostatically chucked or detached in an exposure apparatus when the pattern of the reflective mask is transferred to a transfer target on a semiconductor substrate or the like using an exposure apparatus, and to provide a method for manufacturing a semiconductor device using the reflective mask.

[0013] In order to solve the above problems, this embodiment has the following configuration.

[0014] (Configuration 1) Configuration 1 includes a substrate; and a conductive film formed on a first main surface of the substrate, wherein the conductive film contains Ta4f in a spectrum of Ta4f normalized by the maximum intensity value of the Ta4f peak obtained by analyzing the conductive film by X-ray photoelectron spectroscopy. ５／２ Peak and Ta4f ７／２ The minimum intensity value between the peaks and the Ta4f ５／２ Peak and the Ta4f ７／２ The substrate with a conductive film is characterized by including a first region in which the difference D between the interpolated value of the intensity at the binding energy of the minimum intensity value on a linear interpolation function obtained by linear interpolation based on the peaks is 0.5 or less.

[0015] (Structure 2) Structure 2 is the substrate with a conductive film of Structure 1, wherein the first region of the conductive film contains tantalum and at least one of nitrogen and boron, and the total content of tantalum, nitrogen, and boron in the first region is 95 atomic % or more.

[0016] (Configuration 3) Configuration 3 is the substrate with a conductive film according to configuration 1 or 2, wherein the first region of the conductive film contains 95 atomic % or more of tantalum.

[0017] (Configuration 4) Configuration 4 is the substrate with a conductive film according to configuration 1 or 2, wherein the first region of the conductive film contains 15 atomic % or more of nitrogen.

[0018] (Configuration 5) Configuration 5 is the substrate with a conductive film of any one of Configurations 1 to 4, wherein the conductive film includes a lower layer formed on the first main surface of the substrate and an upper layer formed on the lower layer, and at least one of the lower layer and the upper layer has the first region.

[0019] (Configuration 6) Configuration 6 is the substrate with a conductive film according to configuration 5, wherein the upper layer contains more oxygen than the lower layer.

[0020] (Configuration 7) Configuration 7 is a multilayer reflective film-coated substrate, characterized in that a multilayer reflective film in which high-refractive index layers and low-refractive index layers are alternately stacked is formed on a second main surface opposite the first main surface of the conductive film-coated substrate of any one of Configurations 1 to 6.

[0021] (Configuration 8) Configuration 8 is a reflective mask blank characterized in that an absorber film is formed on the multilayer reflective film of the multilayer reflective film-coated substrate of configuration 7.

[0022] (Configuration 9) Configuration 9 is a reflective mask characterized by having an absorber pattern obtained by etching the absorber film of the reflective mask blank of configuration 8.

[0023] (Configuration 10) Configuration 10 is a method for manufacturing a semiconductor device, comprising the step of transferring the absorber pattern onto a transfer target by exposure using the reflective mask of configuration 9.

[0024] According to the present invention, it is possible to provide a substrate with a conductive film, a substrate with a multilayer reflective film, and a reflective mask blank for manufacturing a reflective mask that can suppress the generation of particles when the reflective mask is electrostatically chucked or detached within an exposure apparatus when the pattern of the reflective mask is transferred to a target on a semiconductor substrate or the like using an exposure apparatus.

[0025] Furthermore, according to the present invention, it is possible to provide a reflective mask that can suppress the generation of particles when the reflective mask is electrostatically chucked or detached in an exposure apparatus when the pattern of the reflective mask is transferred to a transfer target on a semiconductor substrate or the like using an exposure apparatus. Furthermore, according to the present invention, it is possible to provide a method for manufacturing a semiconductor device using the reflective mask.

[0026] FIG. 1 is a cross-sectional view schematically showing an example of the configuration of a conductive film-provided substrate of this embodiment; FIG. 2 is a cross-sectional view schematically showing another example of the configuration of a conductive film-provided substrate of this embodiment; FIG. 3 is a cross-sectional view schematically showing an example of the configuration of a conductive film-provided substrate (multilayer reflective film-provided substrate) of this embodiment; FIG. 4 is a cross-sectional view schematically showing another example of the configuration of a conductive film-provided substrate (multilayer reflective film-provided substrate) of this embodiment; FIG. 5 is a cross-sectional view schematically showing an example of the configuration of a reflective mask blank of this embodiment; FIG. 6 is a cross-sectional view schematically showing another example of the configuration of a reflective mask blank of this embodiment; FIG. 7 is a cross-sectional view schematically showing an example of a method for manufacturing a reflective mask of this embodiment; FIG. 8 is a schematic view showing an example of an EUV exposure apparatus; FIG. 9 is a view showing an example of a spectrum of a Ta4f peak obtained by analyzing the conductive film of the conductive film-provided substrate of this embodiment by X-ray photoelectron spectroscopy (XPS).

[0027] Hereinafter, embodiments of the present invention will be described in detail. Note that the following embodiments are forms for realizing the present invention, and are not intended to limit the scope of the present invention.

[0028] FIG. 1 is a cross-sectional view showing an example of a conductive film-coated substrate 40 according to this embodiment. The conductive film-coated substrate 40 according to this embodiment has a structure in which a conductive film 42 is disposed on one main surface (first main surface or back surface) of a substrate 10. In this specification, the conductive film-coated substrate 40 refers to a substrate 10 having a conductive film 42 formed on at least one main surface (first main surface or back surface) of the substrate 10. The conductive film-coated substrate 40 also includes a multilayer reflective film-coated substrate 20 (see FIGS. 3 and 4 ) having a multilayer reflective film 21 formed on the other main surface (second main surface or front surface), and a reflective mask blank 100 (see FIGS. 5 and 6 ) having an absorber film 24 further formed thereon. In this specification, the conductive film 42 may also be referred to as a back surface conductive film.

[0029] Fig. 2 is a cross-sectional schematic diagram showing another example of a conductive film-attached substrate 40 of this embodiment. The conductive film 42 of the conductive film-attached substrate 40 of this embodiment can be composed of multiple layers of different compositions. Fig. 2 shows an example in which the conductive film 42 is composed of two layers, a lower layer 44 and an upper layer 46. In this specification, the layer closer to the substrate 10 is referred to as the lower layer 44, and the layer farther from the substrate 10 is referred to as the upper layer 46.

[0030] Fig. 3 shows an example of a multilayer reflective film-coated substrate 20. A multilayer reflective film 21 is formed on the second main surface of a substrate 10 of the multilayer reflective film-coated substrate 20 shown in Fig. 3. A conductive film 42 is formed on the first main surface (rear surface) of the substrate 10 of the multilayer reflective film-coated substrate 20 shown in Fig. 3. The multilayer reflective film-coated substrate 20 shown in Fig. 3 is a type of conductive film-coated substrate 40, since it includes the conductive film 42 on the first main surface (rear surface) of the substrate 10.

[0031] Fig. 4 shows another example of a multilayer reflective film-coated substrate 20. A multilayer reflective film 21 and a protective film 22 are formed on the main surfaces of the multilayer reflective film-coated substrate 20 shown in Fig. 4. A conductive film 42 is formed on the first main surface (rear surface) of the substrate 10 of the multilayer reflective film-coated substrate 20 shown in Fig. 4. The multilayer reflective film-coated substrate 20 shown in Fig. 4 is a type of conductive film-coated substrate 40, since it includes the conductive film 42 on the first main surface (rear surface) of the substrate 10.

[0032] Fig. 5 is a cross-sectional schematic diagram showing an example of a reflective mask blank 100 of this embodiment. The reflective mask blank 100 of Fig. 5 has a multilayer reflective film 21, a protective film 22, and an absorber film 24 on the second main surface of the substrate 1. The reflective mask blank 100 shown in Fig. 5 also has a conductive film 42 on the first main surface (rear surface). Therefore, the reflective mask blank 100 shown in Fig. 5 is a type of substrate 40 with a conductive film.

[0033] Fig. 6 is a cross-sectional schematic diagram showing another example of a reflective mask blank 100 of the present embodiment. The reflective mask blank 100 shown in Fig. 6 has an etching mask film 25 on an absorber film 24. The reflective mask blank 100 of the present embodiment also includes a conductive film 42 on the back surface (first main surface). Therefore, the reflective mask blank 100 shown in Fig. 6 is a type of substrate 40 with a conductive film.

[0034] Furthermore, in the reflective mask blank 100 shown in Figure 5 in which the etching mask film 25 is not formed, the absorber film 24 may have a laminated structure of multiple layers, and the materials constituting these multiple layers may be materials having different etching properties, thereby providing the absorber film 24 with an etching mask function.

[0035] In this specification, the phrase "thin film B is disposed (formed) on thin film A (or substrate 10)" not only means that thin film B is disposed (formed) in contact with the surface of thin film A (or substrate 10), but also means that another thin film C is present between thin film A (or substrate 10) and thin film B. Furthermore, in this specification, for example, "thin film B is disposed in contact with the surface of thin film A (or substrate 10)" means that thin film A (or substrate 10) and thin film B are disposed so as to be in direct contact with each other, without any other thin film interposed between them. Furthermore, in this specification, "on" does not necessarily mean the upper side in the vertical direction. "on" merely indicates the relative positional relationship between the thin film, the substrate 10, etc.

[0036] The conductive film-coated substrate 40, the multilayer reflective film-coated substrate 20, the reflective mask blank 100, and the reflective mask 200 of this embodiment will be specifically described.

[0037] [Substrate 10] First, the substrate 10 that can be used to manufacture the conductive film-coated substrate 40 and the like of this embodiment will be described below.

[0038] The substrate 10 has two main surfaces and four end faces that face each other. When the conductive film-attached substrate 40 of this embodiment is used, for example, in a reflective mask blank 100 for EUV exposure, it is preferable to use a glass substrate as the substrate 10. In particular, to prevent distortion of the pattern due to heat during exposure, the substrate 10 is preferably a glass substrate having a thickness of 0±1.0×10 －７ / °C, more preferably 0±0.3×10 －７ Materials having a low thermal expansion coefficient within this range are preferably used. Examples of materials having a low thermal expansion coefficient within this range include SiO ２ -TiO ２ Glasses, multi-component glass ceramics, etc. can be used.

[0039] The substrate 10 preferably has high rigidity to prevent deformation due to film stress of the thin films (such as the multilayer reflective film 21) formed thereon. In particular, it is preferable that the substrate 10 has a high Young's modulus of 65 GPa or more.

[0040] The main surface (second main surface) of the substrate 10 on which the transfer pattern is formed is surface-processed to have a high degree of flatness in order to improve at least the pattern transfer accuracy and positional accuracy. In the case of EUV exposure, the flatness in a 142 mm × 142 mm area of ​​the main surface (second main surface) on which the transfer pattern is formed of the substrate 10 is preferably 0.1 μm or less, and particularly preferably 0.05 μm or less. In this specification, flatness is a value representing the surface warpage (deformation amount) indicated by TIR (Total Indicated Reading). This value is the absolute value of the difference in height between the highest position on the surface of the substrate 10 above the focal plane, which is defined by the least squares method with the surface of the substrate 10 as the focal plane, and the lowest position on the surface of the substrate 10 below the focal plane.

[0041] In the case of EUV exposure, the substrate 10 is made of SiO as described above. ２ -TiO ２ A material having a low thermal expansion coefficient, such as silicon-based glass, is preferably used. For the purpose of reducing the surface roughness of the substrate 10 or reducing defects on the surface of the substrate 10, an underlayer may be formed on the main surface of the substrate 10 on which the transfer pattern is to be formed, as necessary. The material of such an underlayer does not need to be transparent to the exposure light. As the material of the underlayer, a material that can provide high smoothness when the surface of the underlayer is precision polished and that provides good defect quality can be preferably used. For example, Si or a silicon compound containing Si (e.g., SiO ２ Silicon compounds (e.g., silicon dioxide, silicon oxynitride ...

[0042] The surface of the underlayer is preferably precision-polished to have the smoothness required for the substrate 10 for the reflective mask blank 100. The surface of the underlayer is desirably precision-polished to a root-mean-square roughness (Rq) of 0.15 nm or less, particularly preferably 0.1 nm or less. Furthermore, in consideration of the influence on the surface of the multilayer reflective film 21 formed on the underlayer, the surface of the underlayer is desirably precision-polished so that, in relation to the maximum height (Rmax), Rmax / Rq is preferably 2 to 10, particularly preferably 2 to 8. The film thickness of the underlayer is preferably in the range of 10 nm to 300 nm, for example.

[0043] [Substrate 40 with Conductive Film] Next, the substrate 40 with conductive film of this embodiment will be described. The substrate 40 with conductive film of this embodiment includes the substrate 10 and a conductive film 42 formed on the first main surface of the substrate 10.

[0044] 1 and 2 , the conductive-film-coated substrate 40 of this embodiment has a structure in which a predetermined conductive film 42 is disposed on one main surface (first main surface, back surface) of the substrate 10. The conductive film 42 (back surface conductive film) is disposed to facilitate fixation of the reflective mask 200 by an electrostatic chuck.

[0045] As shown in FIG. 1, the conductive film 42 can be made of a single layer. When the conductive film 42 is a single layer, the film formation process is simplified. Alternatively, the conductive film 42 can be a laminated film made of multiple layers. When the conductive film 42 is a laminated film, as shown in FIG. 2, the conductive film 42 can be made of two layers: a lower layer 44 on the substrate 10 side and an upper layer 46 formed on the lower layer 44.

[0046] The conductive film 42 of the conductive film-coated substrate 40 of this embodiment preferably includes a lower layer 44 formed on the first main surface of the substrate 10 and an upper layer 46 formed on the lower layer 44. In the conductive film-coated substrate 40 of this embodiment, the upper layer 46 preferably contains more oxygen than the lower layer 44.

[0047] When the conductive film 42 is a laminated film, the upper layer 46 of the conductive film 42, which is located farthest from the substrate 10, can be a surface oxide layer of the lower layer 44 formed by oxidizing the surface of the lower layer 44. In this case, the conductive film 42 has a surface oxide layer (upper layer 46) with a very small thickness, which is located farthest from the substrate 10. When this upper layer 46 is included, the upper layer 46 contains more oxygen than the lower layer 44. The thickness of the surface oxide layer (upper layer 46) can be 4 nm or less, preferably 2 nm or less, and more preferably 1 nm or less. When the conductive film 42 has the surface oxide layer (upper layer 46), the generation of particles during electrostatic chucking can be further suppressed.

[0048] Furthermore, when the conductive film 42 is a laminated film, the upper layer 46 of the laminated film, which is disposed farthest from the substrate 10, can be an oxide film layer formed of a material obtained by adding oxygen to the material constituting the lower layer 44. In this case, for example, the oxygen content of the upper layer 46 of the conductive film 42 can be higher than that of other layers, such as the lower layer 44 of the conductive film 42. By disposing the upper layer 46 with a higher oxygen content on the surface of the laminated film opposite the substrate 10, particle generation during electrostatic chuck dechucking can be further suppressed. On the other hand, the upper layer 46 can be made of a different material from the lower layer 44 as long as the function of the conductive film 42 is not impaired, and does not necessarily need to contain oxygen.

[0049] The thickness of the upper layer 46 of the conductive film-coated substrate 40 of this embodiment is preferably 2 nm or more, and more preferably greater than 4 nm. The thickness of the upper layer 46 is preferably 25 nm or less, more preferably 20 nm or less, and even more preferably 15 nm or less. By keeping the thickness of the upper layer 46 within the specified range, particle generation by the upper layer 46 can be further suppressed, while the conductive film 42 can function as an electrostatic chuck.

[0050] The overall film thickness of the conductive film 42 can be appropriately controlled within a range that allows an appropriate sheet resistance to be obtained. The film thickness of the conductive film 42 is preferably 10 nm or more, and more preferably 20 nm or more. In order to reduce the surface roughness of the conductive film 42, the film thickness of the conductive film 42 is preferably 500 nm or less, more preferably 200 nm or less, and even more preferably 100 nm or less.

[0051] In order for the electrostatic chuck to operate properly, the sheet resistance of the conductive film 42 is preferably 200 Ω / □ (square) or less, more preferably 100 Ω / □ or less, even more preferably 75 Ω / □ or less, and particularly preferably 50 Ω / □ or less. By adjusting the composition and film thickness of the conductive film 42, a conductive film 42 with an appropriate sheet resistance can be obtained.

[0052] Furthermore, the interface region of the conductive film 42 with the substrate 10 (substrate interface region) and the surface region of the conductive film 42 farthest from the first main surface of the substrate 10 can both be compositionally graded regions in which the composition ratio of the conductive film 42 changes continuously. In this specification, "the conductive film 42 is composed of a single layer" also includes the case where the conductive film 42 is composed of a compositionally graded region (surface region and substrate interface region) and an internal region other than the compositionally graded region (a region in which the composition ratio is uniform in the film thickness direction). In this specification, "a region in which the composition ratio is uniform in the film thickness direction" means a region in which the difference in each constituent element in the film thickness direction is negligibly small. Specifically, "a region in which the composition ratio is uniform in the film thickness direction" means a region in which the difference in each constituent element within the region is 3 atomic % or less.

[0053] In this specification, the "substrate interface region" refers to a region ranging from the interface between the conductive film 42 and the substrate 10 toward the surface (outermost surface) of the conductive film 42 that is farthest from the first main surface of the substrate 10, to a thickness of, for example, more than 0 nm and not more than 5 nm. The thickness of the substrate interface region is more preferably not more than 4 nm, and even more preferably not more than 3 nm.

[0054] In addition, in this specification, the "surface region" refers to a region ranging from the outermost surface of the conductive film 42 toward the first main surface of the substrate 10 to a thickness of, for example, more than 0 nm and not more than 5 nm. The thickness of the surface region is more preferably not more than 4 nm, and even more preferably not more than 3 nm.

[0055] The material of the conductive film 42 in this embodiment is not particularly limited, but preferably contains at least one selected from Ta, Cr, Pt, Au, Rh, Ru, Ir, Nb, and Hf. Preferred examples of the material of the conductive film 42 include tantalum-based materials and chromium-based materials. The conductive film 42 may also contain a noble gas. The noble gas content of the conductive film 42 is preferably 5 atomic % or less, more preferably 3 atomic % or less, and even more preferably 1.5 atomic % or less.

[0056] The tantalum-based material used for the conductive film 42 may be tantalum (Ta) alone, or may contain tantalum and one or more elements selected from carbon (C), nitrogen (N), oxygen (O), boron (B), hydrogen (H), etc.

[0057] The tantalum-based material has high cleaning resistance. Therefore, in this embodiment, the conductive film 42 is preferably made of a tantalum-based material. Furthermore, from the viewpoints of chemical resistance and abrasion resistance, it is more preferable that the metal contained in the conductive film 42 is tantalum alone.

[0058] When the conductive film 42 is made of a tantalum-based material, specific examples include TaN, TaB, TaBN, etc. When the conductive film 42 includes a lower layer 44 and an upper layer 46, the lower layer 44 can be made of TaN, TaB, TaBN, etc., and the upper layer 46 can be made of an oxide of TaN, TaB, TaBN, etc.

[0059] When the conductive film 42 contains tantalum, the tantalum content in the tantalum-containing layer of the conductive film 42 is preferably 95 atomic % or more. When the conductive film 42 has a layer containing tantalum and at least one of nitrogen and boron, the total content of tantalum, nitrogen, and boron in the layer is preferably 95 atomic % or more.

[0060] When the conductive film 42 includes multiple layers, all of the multiple layers may be made of a tantalum-based material. Alternatively, at least one of the multiple layers of the conductive film 42 may be made of a tantalum-based material, and the other layers may be made of a material other than a tantalum-based material.

[0061] Furthermore, the chromium-based material used for the conductive film 42 may be chromium (Cr) alone, or may contain chromium and one or more elements selected from carbon (C), nitrogen (N), oxygen (O), boron (B), hydrogen (H), etc.

[0062] In this embodiment, the conductive film 42 preferably has compressive stress. When the conductive film 42 has compressive stress, warping of the substrate 10 caused by the multilayer reflective film 21 can be reduced.

[0063] The conductive film 42 of the conductive-film-coated substrate 40 of this embodiment (sometimes referred to as the "conductive film 42 of this embodiment") includes a predetermined first region. The first region of the conductive film 42 is a region in which a predetermined difference D is 0.5 or less in the Ta4f peak obtained by analyzing the first region by X-ray photoelectron spectroscopy (XPS). The first region may be a region within a predetermined range in the thickness direction of the conductive film 42. That is, the first region may be a region within a predetermined depth range from the surface of the conductive film 42. The conductive film 42 is required to have at least one first region. Alternatively, the conductive film 42 may have two or more first regions. When the conductive film 42 has N first regions (N: a natural number greater than or equal to 1), the first regions may be referred to, in order, as the first region, second region, third region, ..., Nth region.

[0064] The predetermined depth range can be at least a portion of the internal region of the conductive film 42, excluding the substrate interface region and surface region. The substrate interface region can extend from the interface between the conductive film 42 and the substrate 10 toward the outermost surface of the conductive film 42, with a thickness of 5 nm. The surface region can extend from the outermost surface of the conductive film 42 toward the first main surface of the substrate 10, with a thickness of 5 nm. Furthermore, if the conductive film 42 includes multiple layers, the internal region excludes not only the substrate interface region and the surface region, but also the layer interface region within 5 nm of the interface between adjacent layers. Note that, when the thickness of a layer to be analyzed among the multiple layers included in the conductive film 42 is very small (e.g., 10 nm or less), the predetermined depth range can be a region including at least the center position of the layer to be analyzed in the thickness direction. The internal region of a layer to be analyzed that has a small thickness (e.g., 10 nm or less) can be a region within 25% of the total thickness of the layer to be analyzed, both above and below the center position in the thickness direction of the layer to be analyzed.

[0065] The difference D in the first region of the conductive film 42 is greater than 0, preferably 0.01 or greater, more preferably 0.05 or greater, and even more preferably 0.1 or greater.

[0066] FIG. 9 shows the Ta4f ５／２ Peak and Ta4f ７／２ 1 shows an example of a Ta4f peak consisting of two peaks.

[0067] In X-ray photoelectron spectroscopy (XPS), electrons in atoms contained in a substance are excited by X-rays and emitted to the outside as photoelectrons. In XPS, the energy (binding energy) of the emitted photoelectrons is measured to obtain the energy distribution (spectrum) of the photoelectrons.

[0068] When the conductive film 42 of this embodiment is measured by X-ray photoelectron spectroscopy (XPS), the Ta4f peak of photoelectrons due to electrons in the Ta4f orbital is observed in the binding energy range of approximately 20 eV to 30 eV.

[0069] In X-ray photoelectron spectroscopy (XPS) measurements of the conductive film 42, X-rays from an X-ray source are irradiated toward the conductive film 42 of the conductive film-coated substrate 40, and the energy distribution of photoelectrons emitted from the conductive film 42 can be measured. When performing X-ray photoelectron spectroscopy (XPS) of the conductive film 42, the conductive film 42 can be excavated by Ar gas sputtering, for example, by approximately 1 nm per measurement, and XPS measurements can be performed on the surface of the excavated region of the conductive film 42. By repeating the excavation by Ar gas sputtering and the XPS measurements throughout the entire depth of the conductive film 42, XPS measurement results can be obtained for the entire depth of the conductive film 42. The internal region can then be identified from the measurement results. Preferably, the number of integration times in the XPS analysis is 8 or more. This allows for more reliable results.

[0070] The X-ray irradiation region can be any region in the in-plane direction of the conductive film 42. In a top view, the center of the irradiation region preferably coincides with the center of the outermost surface of the conductive film 42. The center of the X-ray irradiation region is the center of the circle of a circular irradiation region. If the outermost surface of the conductive film 42 is rectangular, the center of the outermost surface of the conductive film 42 refers to the intersection of the diagonals of the rectangle. In a top view, the center of the outermost surface of the conductive film 42 preferably coincides with the center (intersection of the diagonals) of the first main surface of the substrate 10. For example, the X-ray irradiation region can be a circular region with a diameter of 200 μm whose center coincides with the center of the outermost surface of the conductive film 42.

[0071] Measurement for analysis by X-ray photoelectron spectroscopy (XPS) is preferably carried out under the following measurement conditions: (Measurement conditions for XPS) X-ray source: AlK α X-ray (1486.6 eV) X-ray irradiation area: diameter 200 μm Measurement range of photoelectron binding energy: 15 eV to 35 eV Photoelectron detection take-off angle: 45 degrees (detection depth approximately 4 to 5 nm) Step size during measurement: 0.25 eV Pass energy during measurement: 58.7 eV

[0072] Under the measurement conditions of the XPS method described above, the detection depth is approximately 4 to 5 nm. Therefore, by performing an analysis in which the conductive film 42 is dug by approximately 1 nm per measurement using Ar gas sputtering, it is possible to measure photoelectrons emitted from a predetermined depth in the depth direction of the conductive film 42.

[0073] When analyzing the conductive film 42 of this embodiment using X-ray photoelectron spectroscopy (XPS), the conductive film 42 is repeatedly excavated by Ar gas sputtering to a depth of approximately 1 nm per measurement. Then, as described above, the Ta4f spectrum is analyzed at any depth within the identified internal region. This allows for determining whether the conductive film 42 has a first region where the predetermined difference D is 0.5 or less.

[0074] When determining whether the conductive film 42 has a first region, it can be determined that the conductive film 42 has a first region if, as a result of measurement and analysis using a predetermined XPS method, a predetermined difference D is 0.5 or less at at least one location in the depth direction within the internal region of the conductive film 42. Furthermore, it can be determined that the conductive film 42 has a first region if the predetermined difference D is 0.5 or less within a depth range of 5 nm or more at any depth within the conductive film 42. The film thickness of the first region is preferably 40% or more, more preferably 50% or more, and even more preferably 60% or more of the total film thickness of the conductive film 42. The film thickness of the first region can be 100% of the total film thickness of the conductive film 42. When the conductive film 42 includes multiple layers, it is sufficient that at least one of the multiple layers satisfies the above condition. More preferably, the thickest layer of the multiple layers satisfies the above condition. Even more preferably, all of the multiple layers satisfies the above condition.

[0075] The predetermined difference D may be constant in the depth (film thickness) direction of the conductive film 42, or may vary in the depth direction. If the difference D varies in the depth direction, it is preferable that the predetermined difference D in the region farthest from the substrate within the tantalum-containing layer is smallest. Even when the conductive film 42 includes multiple layers, it is preferable that the difference D in the tantalum-containing layer farthest from the substrate is smaller than the differences D in the other tantalum-containing layers. This makes it possible to more efficiently suppress embrittlement of the conductive film 42 due to hydrogen.

[0076] FIG. 9 shows the Ta4f ５／２ Peak and Ta4f ７／２ 1 shows an example of a Ta4f peak consisting of two peaks. The predetermined difference D in the Ta4f peaks of the conductive film 42 of this embodiment can be determined as follows.

[0077] First, the conductive film 42 of this embodiment is analyzed by X-ray photoelectron spectroscopy to obtain a spectrum of the binding energy (unit: eV, sometimes simply referred to as the "Ta4f binding energy") of photoelectrons due to the Ta4f orbital. The range of binding energy measured by X-ray photoelectron spectroscopy can be, for example, from 15 eV to 35 eV.

[0078] The spectrum of Ta4f binding energy obtained by measurement using X-ray photoelectron spectroscopy (XPS) can be processed by subtracting the background, etc. However, since the signal intensity of the Ta4f peak is generally strong, it is not necessary to subtract the background.

[0079] The peak of the Ta4f spectrum (Ta4f peak) is Ta4f ５／２ Peak and Ta4f ７／２ Next, the Ta4f spectrum is normalized by the maximum intensity value of the Ta4f peak. That is, each of the intensity values ​​at each binding energy is divided by the maximum intensity value of the Ta4f peak so that the maximum intensity value of the Ta4f peak becomes 1. Next, the Ta4f of the normalized Ta4f spectrum is calculated. ５／２ Peak and Ta4f ７／２ Based on the two peaks (the binding energy corresponding to the peak position and the normalized maximum intensity), a linear interpolation function L(Ta4f ５／２ Peak and Ta4f ７／２ Next, obtain a line L that passes through the two peaks of the Ta4f spectrum. ５／２ Peak and Ta4f ７／２ The minimum intensity value between two peaks of the peak I ｍｉｎ The bond energy Eｍｉｎ Interpolated value of the intensity at ｍｉｎ Intensity value I of linear interpolation function L at Ｄ ) is then obtained by interpolating the intensity value I Ｄ ) to find the minimum intensity value I ｍｉｎ The predetermined difference D can be obtained by subtracting the above. The conductive film 42 of the conductive film-coated substrate 40 of this embodiment includes a first region in which the predetermined difference D of the Ta4f peak obtained in this manner is 0.5 or less.

[0080] The spectrum of Ta4f is composed of multiple Ta4f ５／２ Peak and / or Ta4f ７／２ In such cases, multiple Ta4f peaks may be present. ７／２ Peak and / or Ta4f ５／２ Among the peaks, the peak Pmax having the highest intensity and the Ta4f derived from tantalum having the same oxidation number as the peak Pmax are ５／２ Peak (or Ta4f ７／２ Peak) Px can be used.

[0081] Furthermore, if the conductive film 42 contains multiple tantalums with different oxidation states, and the spectrum of Ta4f has a broad peak, peak separation can be performed by fixing the peak positions and full width at half maximum (FWHM) corresponding to the oxidation states of tantalum, as shown below. From the multiple peaks obtained by peak separation, the Pmax and Px can be determined, and the difference D can be calculated. Ta4f for peak separation ５／２ In peak fitting, the peak position (binding energy) is ０ :23.42eV, Ta １＋ :24.4±0.10eV, Ta ２＋ :25.2±0.30eV, Ta ３＋ :26.2±0.20eV, Ta ４＋ :27.6±0.30eV, Ta ５＋ : 28.9±0.05 eV, FWHM is Ta ０ :0.73eV, Ta １＋ :1.45eV, Ta ２＋:1.45eV, Ta ３＋ :1.45eV, Ta ４＋ :1.45eV, Ta ５＋ : 1.45 eV. ７／２ In peak fitting, the peak position is determined by Ta ０ :21.50eV, Ta １＋ :22.5±0.10eV, Ta ２＋ :23.3±0.30eV, Ta ３＋ :24.3±0.20eV, Ta ４＋ :25.7±0.30eVeV, Ta ５＋ : 27.0 ± 0.05, FWHM is Ta ０ :0.73eV, Ta １＋ :1.45eV, Ta ２＋ :1.45eV, Ta ３＋ :1.45eV, Ta ４＋ :1.45eV, Ta ５＋ : 1.45 eV.

[0082] The higher the binding energy of the peak in the Ta4f spectrum, the higher the resistance to hydrogen. ７／２ The peak binding energy is preferably 22 eV or more.

[0083] The conductive film-coated substrate 40 of this embodiment can be used as a substrate for a reflective mask blank 100 for manufacturing a reflective mask 200. In manufacturing the reflective mask blank 100, the conductive film-coated substrate 40 is placed in a film-forming chamber, and a multilayer reflective film 21 is formed on the second main surface of the substrate 10 of the conductive film-coated substrate 40. In order to reduce noise (background level: BGL) during defect inspection of the multilayer reflective film 21, the multilayer reflective film 21 is formed by ionizing a noble gas (Ar gas, Kr gas, Xe gas, etc.) and H ２ and / or D ２ The present inventors have found that the multilayer reflective film 21 is formed by ion beam sputtering using a gas containing H as a process gas. ２ and / or D ２The inventors have found that hydrogen derived from the above-mentioned materials is mixed into the conductive film 42 and diffuses through the conductive film 42, accumulating at specific crystal grain boundaries of the conductive film 42, resulting in the problem of the conductive film 42 becoming easily embrittled. The hydrogen atoms accumulated at specific crystal grain boundaries combine with other hydrogen atoms over time to form hydrogen molecules. These hydrogen molecules are thought to cause hydrogen embrittlement and delayed fracture of the conductive film 42. Because the diffusion coefficient of hydrogen in tantalum-based materials is high, the problem of the conductive film 42 becoming embrittled due to hydrogen accumulation at specific crystal grain boundaries can become more pronounced in the case of a conductive film 42 made of a tantalum-based material. Furthermore, the inventors have found that embrittlement of the conductive film 42 can cause a problem in that particles are generated when the electrostatic chuck of an exposure apparatus is attached or detached and remain on the electrostatic chuck when a pattern of a reflective mask 200 manufactured using a conductive film-coated substrate 40 is transferred to a transfer target such as a semiconductor substrate 60. If such a problem occurs, the flatness of the reflective mask 200 fixed to the electrostatic chuck may decrease when transferring the pattern of the reflective mask 200, making it difficult to transfer the pattern with high precision.

[0084] On the other hand, the inventors have found that when the conductive film 42 includes a first region in which the predetermined difference D in the Ta4f peaks is 0.5 or less, as in the conductive film 42 of the present embodiment, Ta is likely to function as a hydrogen trapping site. When Ta is likely to function as a hydrogen trapping site, it is possible to suppress the accumulation of hydrogen at specific crystal grain boundaries in the conductive film 42. Therefore, when the conductive film 42 includes a first region in which the predetermined difference D in the Ta4f peaks is 0.5 or less, it is possible to suppress the embrittlement of the conductive film 42. Therefore, by having the conductive film 42 include a first region with the predetermined difference D, it is possible to suppress the generation of particles when the reflective mask 200 is attached to or detached from an electrostatic chuck in an exposure apparatus.

[0085] The following explanation is considered to be the reason why the problem of embrittlement of the conductive film 42 can be suppressed when the conductive film 42 includes a first region in which the difference D falls within the range of the predetermined value. However, the present invention is not limited to this explanation. That is, when the conductive film 42 includes a first region in which the difference D of the Ta4f peak falls within the range of 0.5 or less, the Ta4f constituting the Ta4f peak falls within the range of 0.5 or less. ５／２ Peak and Ta4f ７／２ This means that the widths (e.g., half-widths) of the two peaks of the Ta4f peaks become relatively large. When the widths (e.g., half-widths) of the two Ta4f peaks are large, it is believed that an imbalance in the electron distribution near the tantalum (Ta) atom occurs compared to the case of tantalum (Ta) alone. It is believed that the tantalum (Ta) atom with an imbalance in the electron distribution functions as a trap site for hydrogen. Therefore, when the conductive film 42 includes the first region within the range of the predetermined difference D, hydrogen diffusion can be suppressed, thereby suppressing the problem of embrittlement of the conductive film 42 caused by hydrogen accumulation at specific crystal grain boundaries of the conductive film 42.

[0086] In order to create an imbalance in the electron distribution in the vicinity of the tantalum (Ta) atom, it is preferable to contain other elements in addition to tantalum (Ta).

[0087] The first region of the conductive film 42 of the conductive film-coated substrate 40 of this embodiment preferably contains tantalum (Ta) and at least one of nitrogen (N) and boron (B). Furthermore, in the conductive film-coated substrate 40 of this embodiment, the total content of tantalum (Ta), nitrogen (N), and boron (B) in the first region of the conductive film 42 is preferably 95 atomic % or more, more preferably 98 atomic % or more. The content of tantalum (Ta) in the first region of the conductive film 42 is preferably 40 atomic % or more, even more preferably 50 atomic % or more. The above-mentioned tantalum-based material has high cleaning resistance. Furthermore, by including tantalum (Ta) and at least one of nitrogen (N) and boron (B) in the first region, and by having the total content of these elements be equal to or greater than a predetermined amount, cleaning resistance, abrasion resistance, and smoothness can be improved. Furthermore, when the conductive film 42 is measured by X-ray photoelectron spectroscopy (XPS), the difference D can be set to fall within a predetermined range.

[0088] In the conductive film-coated substrate 40 of this embodiment, the first region of the conductive film 42 preferably contains tantalum (Ta) at 95 atomic % or more, and more preferably at 98 atomic % or more. Because the above-mentioned tantalum-based materials have high cleaning resistance, it is preferable that the tantalum (Ta) content be a predetermined value or more. The upper limit of the tantalum (Ta) content in the first region of the conductive film 42 is 100 atomic %.

[0089] In the conductive film-coated substrate 40 of this embodiment, the first region of the conductive film 42 preferably contains 15 atomic % or more of nitrogen (N), more preferably 18 atomic % or more. The first region of the conductive film 42 preferably contains 50 atomic % or less of nitrogen (N), more preferably 30 atomic % or less, and even more preferably 25 atomic % or less. By including a predetermined amount of nitrogen (N) in the first region of the conductive film 42, the conductive film 42 can be smoothed while maintaining conductivity. When the first region of the conductive film 42 contains boron (B), the nitrogen (N) content of the conductive film 42 can be less than 1 atomic %, and may be below the detection limit.

[0090] When the first region of the conductive film 42 contains boron (B), the boron content is preferably 1 atomic % or more, more preferably 5 atomic % or more. The boron content of the first region is preferably 30 atomic % or less, more preferably 20 atomic % or less, and even more preferably 18 atomic % or less. By including a predetermined content of boron (B) in the first region of the conductive film 42, the smoothness, cleaning resistance, and abrasion resistance of the conductive film 42 can be improved. When the first region of the conductive film 42 contains nitrogen (N), the boron (B) content of the conductive film 42 can be less than 1 atomic %, and may be below the detection limit.

[0091] When the first region of the conductive film 42 contains oxygen, the oxygen content can be 1 atomic % or more. When the first region of the conductive film 42 is located in the outermost surface, surface region, or substrate interface region, the oxygen content is preferably 10 atomic % or more, more preferably 20 atomic % or more, and even more preferably 30 atomic % or more. When the first region of the conductive film 42 is located in the outermost surface, surface region, or substrate interface region, the oxygen content is preferably 70 atomic % or less, more preferably 60 atomic % or less. On the other hand, the oxygen content of the first region of the conductive film 42 may be below the detection limit. When the first region of the conductive film 42 is located in the internal region, the first region does not need to contain oxygen.

[0092] The first region of the conductive film 42 may be in a compositionally graded region where the composition changes continuously. In this case, the average values ​​of the contents of the constituent atoms in the thickness direction of the first region may be used as the contents of the constituent atoms in the entire first region. The compositionally graded region includes a surface region, a substrate interface region, and a layer interface region.

[0093] The difference D is not necessarily determined solely by the composition of the thin film including the first region of the conductive film 42. The film density and / or crystalline state of the thin film also affect the properties of the thin film. Therefore, the conditions for forming the thin film by sputtering are adjusted to form the thin film with a predetermined difference D. For example, a wide range of conditions, such as the pressure in the film formation chamber, the power applied to the sputtering target, the positional relationship between the target and the substrate, such as the distance between the target and the substrate, and the target formation conditions, are adjusted to form the thin film with the predetermined properties. Furthermore, these film formation conditions are specific to the film formation apparatus and are adjusted as appropriate so that the thin film has the predetermined properties.

[0094] The first region preferably extends over at least 50% of the conductive film 42, excluding the outer periphery of the conductive film 42, in a top view, and more preferably over 80%. This makes it possible to more effectively suppress embrittlement of the conductive film 42 due to hydrogen used in forming the multilayer reflective film 21. Furthermore, in order to suppress the influence of hydrogen used in forming a transfer pattern on the semiconductor substrate 60 (transfer substrate) on the conductive film 42, it is particularly preferable for the first region to extend over the entire surface of the conductive film 42 in a top view. This makes it possible to effectively suppress embrittlement due to hydrogen penetrating into the conductive film 42 from the side surfaces of the conductive film 42.

[0095] There are no particular limitations on the method for forming the conductive film 42. In general, sputtering methods (magnetron sputtering, ion beam sputtering, etc.) can be suitably used.

[0096] The conductive film 42 is preferably formed by sputtering using a sputtering target containing a metal, which is the material of the conductive film 42. Specifically, the substrate 10 is rotated on a horizontal plane with the deposition surface of the substrate 10 on which the conductive film 42 is to be formed facing upward, and the conductive film 42 is preferably formed by sputtering a sputtering target facing the deposition surface at a predetermined angle, at a position where the central axis of the substrate 10 is offset from a line passing through the center of the sputtering target and parallel to the central axis of the substrate 10. The predetermined angle is preferably an inclination angle of the sputtering target of 5 degrees or more and 30 degrees or less. Furthermore, the gas pressure during sputtering deposition is preferably 0.03 Pa or more and 0.5 Pa or less. By forming the conductive film 42 using this method, the desired conductive film 42 can be obtained.

[0097] Examples of gases used in sputtering deposition include noble gases (He, Ne, Ar, Kr, and Xe). When using noble gases, krypton (Kr) and / or xenon (Xe), which have a larger atomic weight than argon (Ar), can be used to increase the actual contact area of ​​the surface of the conductive film 42. This is believed to result in an increased static friction coefficient of the conductive film 42. This increases the frictional force (static friction coefficient) between the surface of the conductive film 42 and the chucking surface of the electrostatic chuck of the exposure tool, thereby suppressing misalignment of the reflective mask 200 during pattern transfer. When the conductive film 42 is formed using krypton (Kr) and / or xenon (Xe), the conductive film 42 contains krypton (Kr) and / or xenon (Xe), and the content of other noble gases (He, Ar) in the conductive film 42 is below the detection limit.

[0098] After being formed on the substrate 10, the conductive film 42 is preferably heated under high vacuum without being exposed to the outside air. The high vacuum can be, for example, a state where the pressure is 0.1 Pa or less, and the pressure is 1.0×10 －２ Pa or less, and －３ Pa or less, and more preferably 1.0 × 10 －４Pa or less. The heating temperature is preferably 300°C or more, more preferably 400°C or more, and even more preferably 450°C or more. The heating time is preferably 10 minutes or more. The upper limit of the heating time is not particularly limited, but can be, for example, 2 hours or less. Examples of heating means that can be used include known means such as a hot plate, an oven, and a flash lamp. When the conductive film 42 is heated as described above, in order to maintain a high reflectance of the multilayer reflective film 21 (and the protective film 22) for EUV light, it is preferable that the multilayer reflective film 21 (and the protective film 22) be formed after the conductive film 42 is heated.

[0099] <<Other Thin Films>> The conductive film 42 of the conductive-film-coated substrate 40 of this embodiment may include layers (thin films) other than the conductive film 42 .

[0100] The conductive film-coated substrate 40, the multilayer reflective film-coated substrate 20, and the reflective mask blank 100 of this embodiment can include a bottom layer between the substrate 10 and the conductive film 42. The bottom layer can be, for example, a hydrogen penetration-inhibiting film that inhibits hydrogen from penetrating from the substrate 10 (glass substrate) into the conductive film 42. The presence of the hydrogen penetration-inhibiting film can inhibit hydrogen from being absorbed into the conductive film 42 from the substrate 10, and can inhibit an increase in compressive stress of the conductive film 42.

[0101] The material of the hydrogen penetration inhibiting film may be any type as long as it is a material that is difficult for hydrogen to permeate and can inhibit hydrogen from penetrating from the substrate 10 (glass substrate) into the conductive film 42 .

[0102] The material of the bottom layer is preferably a material containing tantalum and oxygen. Preferred materials for the bottom layer include TaO, TaON, TaBO, and TaBON. The bottom layer may further contain carbon (C), hydrogen (H), and / or a noble gas. When the bottom layer is a hydrogen penetration suppression film, the material of the hydrogen penetration suppression film is preferably a material selected from TaO, TaON, TaBO, and TaBON, and more preferably a material having an oxygen content of 50 atomic % or more. This more effectively suppresses hydrogen penetration into the conductive film 42. The hydrogen penetration suppression film may further contain carbon (C) or a noble gas. The hydrogen penetration suppression film may be a single layer of these materials, or may be a multi-layer film or a compositionally graded film.

[0103] The thickness of the bottom layer is preferably 1 nm or more, and more preferably 3 nm or more. This allows for the formation of a bottom layer with a substantially uniform film thickness and a substantially uniform film composition. The thickness of the hydrogen penetration inhibitor film is preferably 1 nm or more, and more preferably 5 nm or more, and even more preferably 10 nm or more. This allows for an improved effect of preventing hydrogen penetration. Furthermore, by setting the thickness of the hydrogen penetration inhibitor film within the above range, a hydrogen penetration inhibitor film with a substantially uniform film thickness and a substantially uniform film composition can be formed on the main surface of the substrate 10 (glass substrate) by a sputtering method.

[0104] When forming a hydrogen penetration suppression film, it is preferable that the hydrogen penetration suppression film is formed in an area that is the same as or wider than the formation area of ​​the conductive film 42 on the main surface of the substrate 10 (glass substrate) so that the conductive film 42 does not come into contact with the substrate 10 (glass substrate).

[0105] [Multilayer Reflective Film Coated Substrate 20] Next, the multilayer reflective film coated substrate 20 of this embodiment will be described. Figures 3 and 4 show schematic cross-sectional views of examples of the multilayer reflective film coated substrate 20. The above-mentioned conductive film 42 is disposed on the first main surface (rear surface) of the multilayer reflective film coated substrate 20 shown in Figures 3 and 4. The multilayer reflective film coated substrate 20 having the conductive film 42 is a type of conductive film coated substrate 40 of this embodiment.

[0106] <Multilayer reflective film 21> In the multilayer reflective film-coated substrate 20 of the embodiment, a multilayer reflective film 21 is disposed on a second main surface that faces the first main surface of the substrate 10 of the conductive film-coated substrate 40. The multilayer reflective film 21 is a multilayer film in which refractive index layers and low refractive index layers are alternately stacked. The multilayer reflective film 21 imparts the function of reflecting EUV light to the reflective mask 200.

[0107] Generally, the multilayer reflective film 21 is a multilayer film in which thin films (high refractive index layers) of light elements or compounds thereof, which are high refractive index materials, and thin films (low refractive index layers) of heavy elements or compounds thereof, which are low refractive index materials, are alternately stacked in approximately 30 to 60 cycles.

[0108] The multilayer film used as the multilayer reflective film 21 may have a structure in which a high-refractive index layer / low-refractive index layer stacked in this order from the substrate 10 side is stacked multiple times. Alternatively, the multilayer film may have a structure in which a low-refractive index layer / high-refractive index layer stacked in this order from the substrate 10 side is stacked multiple times. The outermost layer of the multilayer reflective film 21, i.e., the top layer of the multilayer reflective film 21 opposite the substrate 10 side, is preferably a high-refractive index layer. In the above-described multilayer film, when a high-refractive index layer / low-refractive index layer stacked in this order from the substrate 10 side is stacked multiple times, the top layer is a low-refractive index layer. In this case, if the low-refractive index layer constitutes the outermost surface of the multilayer reflective film 21, it may be easily oxidized, reducing the reflectivity of the reflective mask 200. Therefore, it is preferable to form the multilayer reflective film 21 by further forming a high-refractive index layer on the uppermost low-refractive index layer. On the other hand, in the above-mentioned multilayer film, when a low-refractive index layer / high-refractive index layer stack structure in which a low-refractive index layer and a high-refractive index layer are stacked in this order from the substrate 10 side is defined as one cycle, and multiple cycles are stacked, the uppermost layer becomes the high-refractive index layer, and therefore, in this case, there is no need to form an additional high-refractive index layer.

[0109] The high-refractive index layer can be a layer containing silicon (Si). Examples of materials containing Si include elemental Si and Si compounds containing Si, boron (B), carbon (C), nitrogen (N), oxygen (O), and / or hydrogen (H). By using a high-refractive index layer containing Si, a reflective mask 200 with excellent reflectivity for EUV light can be obtained. The low-refractive index layer can be a metal element selected from molybdenum (Mo), ruthenium (Ru), rhodium (Rh), and platinum (Pt), or an alloy thereof. These metal elements or alloys may also be doped with boron (B), carbon (C), nitrogen (N), oxygen (O), and / or hydrogen (H). In the multilayer reflective film-coated substrate 20 of this embodiment, the low-refractive index layer is preferably a molybdenum (Mo) layer, and the high-refractive index layer is preferably a silicon (Si) layer. For example, a Mo / Si periodic stacked film in which Mo layers and Si layers are alternately stacked for approximately 30 to 60 periods can be preferably used as the multilayer reflective film 21 for reflecting EUV light with a wavelength of 13 nm to 14 nm (e.g., 13.5 nm). Furthermore, in the multilayer reflective film-coated substrate 20 of this embodiment, the low refractive index layers may be ruthenium (Ru) layers, and the high refractive index layers may be silicon (Si) layers. For example, a Ru / Si periodic stacked film in which Ru layers and Si layers are alternately stacked for approximately 30 to 40 periods can be preferably used as the multilayer reflective film 21 for reflecting EUV light with a wavelength of 13 nm to 14 nm (e.g., 13.5 nm).

[0110] Furthermore, as the multilayer reflective film 21 used in the EUV light region, a Mo / Be periodic laminated film, a Si / Nb periodic laminated film, a Si / Mo / Ru periodic laminated film, a Si / Mo / Ru / Mo periodic laminated film, a Si / Ru / Mo / Ru periodic laminated film, etc. can be used. The material can be appropriately selected depending on the exposure wavelength.

[0111] The reflectance of the multilayer reflective film 21 alone is typically 65% ​​or higher, with the upper limit typically being 73%. The film thickness and period of each constituent layer of the multilayer reflective film 21 can be appropriately selected depending on the exposure wavelength. Specifically, the film thickness and period of each constituent layer of the multilayer reflective film 21 can be selected so as to satisfy the law of Bragg reflection. The multilayer reflective film 21 includes multiple high-refractive index layers and multiple low-refractive index layers, but the film thicknesses of the high-refractive index layers and the low-refractive index layers do not necessarily have to be the same.

[0112] The multilayer reflective film 21 can be formed by a method known in the art. The multilayer reflective film 21 can be formed by depositing each layer by, for example, ion beam sputtering or magnetron sputtering. In the case of the Mo / Si periodic stacked film described above, for example, a Si film about 4 nm thick is first deposited on the substrate 10 using a Si target by ion beam sputtering, and then a Mo film about 3 nm thick is deposited using a Mo target. This constitutes one cycle, and 30 to 60 cycles are stacked to form the multilayer reflective film 21 (the top layer on the outermost surface is a Si film). Note that, although 60 cycles requires more steps than, for example, 30 cycles, the reflectivity for EUV light can be increased.

[0113] The multilayer reflective film 21 preferably contains at least one additive element selected from hydrogen (H), deuterium (D), and helium (He). The atomic density of the additive element in the multilayer reflective film 21 is 0.006 atom / nm ３ 0.50 atoms / nm or more ３ This makes it possible to reduce the background level when inspecting the multilayer reflective film 21 for defects.

[0114] <Protective film 22> The multilayer reflective film-coated substrate 20 (conductive film-coated substrate 40) of this embodiment preferably further includes a protective film 22 arranged in contact with the surface of the multilayer reflective film 21 that is farthest from the substrate 10.

[0115] A protective film 22 can be formed on the multilayer reflective film 21 formed as described above to protect the multilayer reflective film 21 from dry etching and wet cleaning in the manufacturing process of the reflective mask 200 (see FIG. 4 ). In this way, a configuration in which the multilayer reflective film 21 and the protective film 22 are provided on the substrate 10 can also be used as the multilayer reflective film-coated substrate 20 (substrate 40 with a conductive film) of this embodiment.

[0116] In the multilayer reflective film-coated substrate 20 of this embodiment, the protective film 22 is formed on the multilayer reflective film 21, thereby making it possible to suppress damage to the surface of the multilayer reflective film 21 when manufacturing a reflective mask 200 (EUV mask) using the multilayer reflective film-coated substrate 20. As a result, the resulting reflective mask 200 has good reflectance characteristics for EUV light.

[0117] The protective film 22 is formed of, for example, a material containing ruthenium as a main component. Examples of materials containing ruthenium as a main component include simple Ru metal, Ru alloys containing Ru with at least one metal selected from titanium (Ti), niobium (Nb), rhodium (Rh), molybdenum (Mo), zirconium (Zr), yttrium (Y), boron (B), lanthanum (La), cobalt (Co), chromium (Cr), and rhenium (Re), and materials containing nitrogen in these alloys. Incidentally, containing substance A as a main component means containing substance A in an amount of 50% or more.

[0118] Furthermore, materials such as Ru, Rh, Ru-(Nb, Rh, Zr, Y, B, Ti, La, Mo), Si-(Ru, Rh, Cr, B), or Si, Zr, Nb, La, and B can be used as the material for the protective film 22. Among these, the use of a material containing ruthenium (Ru) improves the reflectivity characteristics of the multilayer reflective film 21. Specifically, the material for the protective film 22 is preferably Ru or Ru-(Nb, Rh, Zr, Y, B, Ti, La, Mo). Such a protective film 22 is particularly effective when the absorber film 24 is made of a Ta-based material and is patterned by dry etching with a Cl-based gas.

[0119] The thickness of the protective film 22 is preferably, for example, 1 nm or more, and 5 nm or less.

[0120] The method for forming the protective film 22 is not particularly limited, but typically, ion beam sputtering, magnetron sputtering, or the like is suitable.

[0121] Furthermore, in the multilayer reflective film coated substrate 20 (substrate 40 with a conductive film) of this embodiment, an underlayer may be formed between the substrate 10 and the multilayer reflective film 21. The underlayer can be formed for the purposes of improving the smoothness of the main surface of the substrate 10, reducing defects, enhancing the reflectivity of the multilayer reflective film 21, and correcting stress in the multilayer reflective film 21.

[0122] [Reflective Mask Blank 100] Next, the reflective mask blank 100 of this embodiment will be described. Fig. 5 is a cross-sectional schematic diagram showing an example of the reflective mask blank 100 of this embodiment. The reflective mask blank 100 of this embodiment has a structure in which an absorber film 24 is formed on the multilayer reflective film 21 or on the protective film 22 of the multilayer reflective film-coated substrate 20 described above. The conductive film 42 described above is arranged on the first main surface (rear surface) of the substrate 10 of the reflective mask blank 100 shown in Fig. 5.

[0123] <Absorber Film 24> The absorber film 24 of the reflective mask blank 100 of this embodiment is formed on the multilayer reflective film 21 or the protective film 22. The basic function of the absorber film 24 is to absorb EUV light. The absorber film 24 may be an absorber film 24 designed to absorb EUV light, or an absorber film 24 with a phase shift function that also takes into account the phase difference of EUV light. The absorber film 24 with a phase shift function absorbs EUV light and reflects a portion of it to shift the phase. That is, in a reflective mask 200 patterned with an absorber film 24 with a phase shift function, the portion where the absorber film 24 is formed absorbs and attenuates EUV light while reflecting a portion of the light at a level that does not adversely affect pattern transfer. Furthermore, in regions (field portions) where the absorber film 24 is not formed, the EUV light is reflected from the multilayer reflective film 21 via the protective film 22. Therefore, a desired phase difference is obtained between the light reflected from the absorber film 24 having a phase shift function and the light reflected from the field portion. The absorber film 24 having a phase shift function is formed so that the phase difference between the light reflected from the absorber film 24 and the light reflected from the multilayer reflective film 21 is 170 to 260 degrees. The light beams with inverted phase differences interfere with each other at the pattern edge portion, thereby improving the image contrast of the projected optical image. As the image contrast improves, the resolution increases, and various exposure latitudes such as exposure latitude and focus latitude can be increased.

[0124] The absorber film 24 may be a single-layer thin film (single-layer film) or a multilayer film consisting of multiple films (e.g., a lower-layer absorber film and an upper-layer absorber film). A single-layer film has the advantage of reducing the number of steps in mask blank manufacturing, thereby improving production efficiency. In the case of a multilayer film, the optical constants and film thickness of the upper-layer absorber film can be appropriately set so that it serves as an anti-reflection film during optical mask pattern defect inspection. This improves inspection sensitivity during optical mask pattern defect inspection. Furthermore, using a thin film containing oxygen (O) or nitrogen (N), which improves oxidation resistance, as the upper-layer absorber film improves stability over time. Thus, by forming the absorber film 24 into a multilayer film, various functions can be added. When the absorber film 24 has a phase shift function, forming it into a multilayer film allows for a wider range of optical adjustment, making it easier to obtain a desired reflectance.

[0125] The material of the absorber film 24 is not particularly limited as long as it has the function of absorbing EUV light, can be processed by etching or the like (preferably by dry etching with a chlorine (Cl)-based gas and / or a fluorine (F)-based gas), and has a high etching selectivity relative to the protective film 22. As a material having such a function, at least one metal selected from palladium (Pd), silver (Ag), platinum (Pt), gold (Au), iridium (Ir), tungsten (W), chromium (Cr), cobalt (Co), manganese (Mn), tin (Sn), tantalum (Ta), vanadium (V), nickel (Ni), hafnium (Hf), iron (Fe), copper (Cu), tellurium (Te), zinc (Zn), magnesium (Mg), germanium (Ge), aluminum (Al), rhodium (Rh), ruthenium (Ru), molybdenum (Mo), niobium (Nb), titanium (Ti), zirconium (Zr), yttrium (Y), and silicon (Si), an alloy containing two or more metals, or a compound thereof can be preferably used. The compound may further contain oxygen (O), nitrogen (N), carbon (C), and / or boron (B) in addition to the above metal or alloy.

[0126] The absorber film 24 can be formed by magnetron sputtering such as DC sputtering and RF sputtering. For example, in the case of an absorber film 24 made of a tantalum compound or the like, the absorber film 24 can be formed by a reactive sputtering method using a target containing tantalum and boron and argon gas to which oxygen or nitrogen has been added.

[0127] In terms of smoothness and flatness, the crystalline state of the absorber film 24 is preferably an amorphous or microcrystalline structure. This improves the edge roughness of the absorber pattern 24a, thereby improving the dimensional accuracy of the pattern. The surface roughness of the absorber film 24 is preferably 0.5 nm or less, more preferably 0.4 nm or less, and even more preferably 0.3 nm or less, in root-mean-square roughness (Rms).

[0128] The thickness of the absorber film 24 is preferably in the range of, for example, about 30 nm to 100 nm.

[0129] <Etching Mask Film 25> Figure 6 is a cross-sectional schematic diagram showing another example of the reflective mask blank 100 of this embodiment. The reflective mask blank 100 shown in Figure 6 can have an etching mask film 25 on the absorber film 24. As a material for the etching mask film 25, it is preferable to use a material that has a high etching selectivity ratio of the absorber film 24 to the etching mask film 25. The etching selectivity ratio is a value obtained by dividing the etching rate of the absorber film 24 by the etching rate of the etching mask film 25. The etching selectivity ratio of the absorber film 24 to the etching mask film 25 is preferably 1.5 or more, and more preferably 3 or more.

[0130] The reflective mask blank 100 of this embodiment preferably has an etching mask film 25 on the absorber film 24 .

[0131] Chromium or a chromium compound is preferably used as the material for the etching mask film 25. Examples of chromium compounds include materials containing Cr and at least one element selected from N, O, C, and H. The etching mask film 25 more preferably contains CrN, CrO, CrC, CrON, CrOC, CrCN, or CrOCN, and further preferably is a CrO-based film containing chromium and oxygen (a CrO film, a CrON film, a CrOC film, or a CrOCN film).

[0132] Tantalum or a tantalum compound is preferably used as the material of the etching mask film 25. Examples of tantalum compounds include a material containing Ta and at least one element selected from N, O, B, and H. More preferably, the etching mask film 25 contains TaN, TaO, TaON, TaBN, TaBO, or TaBON.

[0133] Silicon or a silicon compound is preferably used as the material for the etching mask film 25. Examples of silicon compounds include a material containing Si and at least one element selected from N, O, C, and H, as well as metal silicon (metal silicide) and metal silicon compounds (metal silicide compounds) containing a metal in silicon or a silicon compound. Examples of metal silicon compounds include a material containing a metal, Si, and at least one element selected from N, O, C, and H.

[0134] The thickness of the etching mask film 25 is preferably 3 nm or more in order to form a pattern with high precision in the absorber film 24. Moreover, the thickness of the etching mask film 25 is preferably 15 nm or less in order to make the thickness of the resist film 32 thin.

[0135] Furthermore, the reflective mask blank 100 of this embodiment can also be configured such that the absorber film 24 is composed of a laminated film of a top layer and other layers made of materials with different etching selectivities, with the top layer functioning as an etching mask film 25 for the other layers.

[0136] <Resist film 32> The reflective mask blank 100 of the embodiment also includes an embodiment in which a resist film 32 is formed on the absorber film 24 (or on the etching mask film 25, if any). Such a resist film 32 is used when patterning the absorber film 24 of the reflective mask blank 100 by lithography in the manufacturing process of the reflective mask 200.

[0137] 7D , the reflective mask 200 of this embodiment has an absorber pattern 24a obtained by patterning, by etching, the absorber film 24 of the above-mentioned reflective mask blank 100. The reflective mask 200 shown in FIG. 7D has the above-mentioned conductive film 42 on the first main surface (rear surface) of the substrate 10.

[0138] 7A to 7D are cross-sectional schematic views showing an example of a method for manufacturing the reflective mask 200. The reflective mask blank 100 of the present embodiment described above can be used to manufacture the reflective mask 200 of the present embodiment. An example of the method for manufacturing the reflective mask 200 will be described below.

[0139] First, a reflective mask blank 100 is prepared, which includes a substrate 10, a multilayer reflective film 21 formed on the substrate 10, a protective film 22 formed on the multilayer reflective film 21, and an absorber film 24 formed on the protective film 22. Next, a resist film 32 is formed on the absorber film 24 to obtain the reflective mask blank 100 with the resist film 32 (FIG. 7A). A pattern is written on the resist film 32 using an electron beam lithography device, and a development and rinsing process is then performed to form a resist pattern 32a (FIG. 7B).

[0140] Using the resist pattern 32a as a mask, the absorber film 24 is dry-etched, whereby the portions of the absorber film 24 that are not covered by the resist pattern 32a are etched, and an absorber pattern 24a is formed (FIG. 7C).

[0141] As the etching gas for the absorber film 24, for example, a fluorine-based gas and / or a chlorine-based gas can be used. As the fluorine-based gas, CF ４ , CHF ３, C ２ F ６ , C ３ F ６ , C ４ F ６ , C ４ F ８ , C.H. ２ F ２ , C.H. ３ F, C ３ F ８ , SF ６ , and F ２ The chlorine-based gas may be Cl ２ , SiCl ４ , CHCl ３ , CCl ４ , and BCl ３ In addition, a fluorine-based gas and / or a chlorine-based gas and O ２ In this case, a mixed gas containing a predetermined ratio of these may be used. These etching gases may further contain an inert gas such as He and / or Ar, if necessary.

[0142] After the absorber pattern 24a is formed, the resist pattern 32a is removed with a resist remover solution, and after the resist pattern 32a is removed, a wet cleaning process using an acidic or alkaline aqueous solution is performed to obtain the reflective mask 200 of this embodiment (FIG. 7D).

[0143] In addition, when a reflective mask blank 100 in which an etching mask film 25 is formed on an absorber film 24 is used, an additional process is performed in which a pattern (etching mask pattern) is formed on the etching mask film 25 using the resist pattern 32a as a mask, and then a pattern is formed on the absorber film 24 using the etching mask pattern as a mask.

[0144] The reflective mask 200 thus obtained has a structure in which a multilayer reflective film 21, a protective film 22, and an absorber pattern 24a are laminated on the substrate 10.

[0145] An exposed region (reflective region) of the multilayer reflective film 21 covered with the protective film 22 has the function of reflecting EUV light. An area where the multilayer reflective film 21 and the protective film 22 are covered with the absorber pattern 24 a has the function of absorbing EUV light. By using the reflective mask 200 of this embodiment, a reflective region with high reflectivity for EUV light can be obtained, and therefore, in EUV lithography, a finer pattern can be transferred onto a transfer target.

[0146] The protective film 22 in the region exposed by forming the absorber pattern 24a may be eventually removed. On the other hand, if the protective film 22 remains but does not affect the function of the reflective mask 200, it is not necessary to remove the protective film 22. Furthermore, when the reflective mask 200 is manufactured using the reflective mask blank 100 having a configuration including the above-described etching mask film 25, the etching mask film 25 may be eventually removed. On the other hand, if the etching mask film 25 remains but does not affect the function of the reflective mask 200, it is not necessary to remove the etching mask film 25.

[0147] The reflective mask 200 of this embodiment has the above-described conductive film 42 on the first main surface (rear surface) of the substrate 10. The reflective mask 200 of this embodiment has the predetermined conductive film 42, which can suppress diffusion of hydrogen contained in the conductive film 42. This can suppress the problem of embrittlement of the conductive film 42 caused by hydrogen accumulating at specific crystal grain boundaries in the conductive film 42. Therefore, when a pattern of the reflective mask 200 of this embodiment is transferred to a transfer target on a semiconductor substrate 60 or the like using an exposure apparatus, it is possible to suppress the generation of particles when the reflective mask 200 is electrostatically chucked or detached within the exposure apparatus.

[0148] [Method for Manufacturing Semiconductor Device] The method for manufacturing a semiconductor device according to this embodiment includes a step of transferring a pattern of the absorber film 24 onto a transfer target by exposure using the above-described reflective mask 200. This step can be performed by using the above-described reflective mask 200 to perform a lithography process using an exposure apparatus to form a transfer pattern on the transfer target.

[0149] By lithography using the reflective mask 200 of this embodiment, a transfer pattern can be formed on a transfer target such as a semiconductor substrate 60. This transfer pattern has a shape that is the result of transferring the pattern of the reflective mask 200. By forming a transfer pattern on the semiconductor substrate 60 using the reflective mask 200, a semiconductor device can be manufactured.

[0150] According to this embodiment, a semiconductor device can be manufactured using the reflective mask 200 that can suppress the generation of particles when the reflective mask 200 is electrostatically chucked or detached in an exposure apparatus. Therefore, by using the reflective mask 200 of this embodiment, semiconductor devices can be manufactured with higher density and precision.

[0151] A method of transferring a pattern onto a semiconductor substrate 60 with a resist by using EUV light will be described with reference to FIG.

[0152] 8 shows a schematic configuration of an EUV exposure apparatus 50, which is an apparatus for transferring a transfer pattern onto a resist film formed on a semiconductor substrate 60. The EUV exposure apparatus 50 includes an EUV light generation unit 51, an irradiation optical system 56, a reticle stage 58, a projection optical system 57, and a wafer stage 59, which are precisely arranged along the optical path axis of the EUV light. The container of the EUV exposure apparatus 50 is filled with hydrogen gas.

[0153] The EUV light generation unit 51 has a laser light source 52, a tin droplet generation unit 53, a capture unit 54, and a collector 55. When the high-power carbon dioxide laser from the laser light source 52 irradiates the tin droplets emitted from the tin droplet generation unit 53, the tin droplets are converted into plasma, and EUV light is generated. The generated EUV light is collected by the collector 55 and passes through an irradiation optical system 56 to be incident on a reflective mask 200 set on a reticle stage 58. The EUV light generation unit 51 generates EUV light with a wavelength of, for example, 13.53 nm.

[0154] The EUV light reflected by the reflective mask 200 is reduced by the projection optical system 57 to a pattern image light, typically about one-fourth the original size, and projected onto the semiconductor substrate 60 (transferred substrate 10). As a result, a given circuit pattern is transferred onto the resist film on the semiconductor substrate 60. A resist pattern can be formed on the semiconductor substrate 60 by developing the exposed resist film. An integrated circuit pattern can be formed on the semiconductor substrate 60 by etching the semiconductor substrate 60 using the resist pattern as a mask. A semiconductor device is manufactured through these and other necessary processes.

[0155] By using the reflective mask 200 manufactured using the conductive film-coated substrate 40 of this embodiment, it is possible to suppress diffusion of hydrogen contained in the conductive film 42. As a result, it is possible to suppress the problem of embrittlement of the conductive film 42 caused by accumulation of hydrogen at specific crystal grain boundaries of the conductive film 42. Therefore, when a pattern of the reflective mask 200 of this embodiment is transferred to a transfer target on a semiconductor substrate 60 or the like using an exposure apparatus, it is possible to suppress generation of particles when the reflective mask 200 is electrostatically chucked or detached within the exposure apparatus.

[0156] Hereinafter, examples of manufacturing the conductive film-coated substrate 40, the multilayer reflective film-coated substrate 20, the reflective mask blank 100, and the reflective mask 200 of this embodiment will be described as examples. These examples do not limit the present invention.

[0157] First, a conductive film 42 was formed on the first main surface (rear surface) of the substrate 10 for EUV exposure as described below, to produce the conductive film-coated substrates 40 of Examples 1 to 9 and Comparative Examples 1 and 2.

[0158] <Preparation of Substrate 10> The substrate 10 used to manufacture the conductive film-attached substrate 40 of Examples 1 to 9 and Comparative Examples 1 and 2 was prepared as follows.

[0159] First, a SiO 6025 size (approximately 152 mm × approximately 152 mm × 6.35 mm) low-thermal expansion glass substrate with both the first and second main surfaces polished was prepared. ２ -TiO ２A SiO2-based glass substrate was prepared. The main surface of the substrate 10 was polished to a flat and smooth finish through a rough polishing process, a precision polishing process, a local processing process, and a touch polishing process. The substrate 10 had a smooth surface with a root-mean-square roughness (Rq) of 0.25 nm and a flatness of 100 nm or less. The surface roughness was measured using an atomic force microscope (AFM) over a 1 μm × 1 μm measurement area.

[0160] <Fabrication of Conductive Film 42> Conductive film 42 was formed on the first main surface of substrate 10 in the above-described Examples 1 to 9 and Comparative Examples 1 and 2 as follows. As shown in Table 1, the conductive film 42 in Examples 1 to 4 and Comparative Examples 1 and 2 is a single-layer conductive film 42. The conductive film 42 in Examples 5 to 9 is a two-layer conductive film 42 consisting of a lower layer 44 and an upper layer 46.

[0161] First, under the conditions shown in Table 1, the conductive films 42 of Examples 1 to 4 and Comparative Examples 1 and 2, and the lower layers 44 of the conductive films 42 of Examples 5 to 9 were formed.

[0162] The conductive film 42 in Example 1 and the lower layer 44 in Examples 5 and 8 were formed by placing a TaB target facing the rear surface (first main surface) of the substrate 10 and using Xe gas and N ２ Sputtering (or reactive sputtering) was performed in a mixed gas atmosphere of Xe gas and N gas. ２ Indicates the gas flow rate (flow rate %).

[0163] The conductive film 42 in Examples 2 and 4 and the lower layer 44 in Examples 6, 7, and 9 were formed by placing a Ta target facing the rear surface (first main surface) of the substrate 10 and using Xe gas and N ２ Sputtering (or reactive sputtering) was performed in a mixed gas atmosphere of Xe gas and N gas. ２ Indicates the gas flow rate (flow rate %).

[0164] The conductive film 42 of Example 3 was formed by placing a Ta target opposite the rear surface (first main surface) of the substrate 10 and performing sputtering in a Xe gas atmosphere.

[0165] In Example 5, the upper layer 46 of the conductive film 42 was formed by placing a TaB target facing the rear surface (first main surface) of the substrate 10 and using Xe gas and O ２Reactive sputtering was carried out in a mixed gas atmosphere of Xe gas and O gas. ２ Indicates the gas flow rate (flow rate %).

[0166] In Example 6, the upper layer 46 of the conductive film 42 was formed by placing a Ta target facing the rear surface (first main surface) of the substrate 10 and using Xe gas and O ２ Reactive sputtering was carried out in a mixed gas atmosphere of Xe gas and O gas. ２ Indicates the gas flow rate (flow rate %).

[0167] The upper layer 46 of the conductive film 42 in Example 7 was formed by sputtering in an Ar gas atmosphere with an Ir target facing the rear surface (first main surface) of the substrate 10 .

[0168] The upper layer 46 of the conductive film 42 in Example 8 was formed by sputtering in an Ar gas atmosphere with a RuNb target facing the rear surface (first main surface) of the substrate 10 .

[0169] The upper layer 46 of the conductive film 42 in Example 9 was formed by placing a RuRhCr target facing the rear surface (first main surface) of the substrate 10 and using Ar gas and N ２ Reactive sputtering was carried out in a mixed gas atmosphere of Ar gas and N gas. ２ Indicates the gas flow rate (flow rate %).

[0170] After the conductive film 42 of Examples 1 to 9 was formed on the substrate 10, the substrate 10 was heated under a pressure of 1.0×10 －４ The mixture was heated at 400° C. for 10 minutes under a high vacuum of 1000 Pa or less.

[0171] In Comparative Examples 1 and 2, the conductive film 42 was formed by placing a Ta target facing the rear surface (first main surface) of the substrate 10 and using Ar gas and N ２ Reactive sputtering was carried out in a mixed gas atmosphere of Ar gas and N gas. ２ The gas flow rate ratio (flow rate %) is shown. The conductive films 42 of Comparative Examples 1 and 2 were not heated under high vacuum.

[0172] Table 1 shows the film thickness of the conductive film 42 in Examples 1 to 4 and Comparative Examples 1 and 2, and the film thickness of the lower layer 44 and upper layer 46 in Examples 5 to 9. The film thickness of the conductive film 42 in Examples 1 to 4 and Comparative Examples 1 and 2 was adjusted by adjusting the film formation time. Similarly, the film thickness of the lower layer 44 and upper layer 46 in Examples 5 to 9 was adjusted by adjusting the film formation time.

[0173] Table 1 shows the composition ratios (atomic %) of the conductive films 42 formed as described above in Examples 1 to 4 and Comparative Examples 1 and 2, and the lower layer 44 and upper layer 46 in Examples 5 to 9. The composition ratios of the conductive films 42 (lower layer 44 and upper layer 46) were measured by X-ray photoelectron spectroscopy (XPS).

[0174] In this manner, the conductive film-attached substrates 40 of Examples 1 to 9 and Comparative Examples 1 and 2 were produced.

[0175] <Measurement by X-ray Photoelectron Spectroscopy (XPS)> The Ta4f spectra of the conductive films 42 of the conductive-film-attached substrates 40 of Examples 1 to 9 and Comparative Examples 1 and 2 were analyzed by X-ray photoelectron spectroscopy (XPS). Specifically, the binding energies of photoelectrons excited by X-rays irradiated onto the conductive films 42 of the conductive-film-attached substrates 40 of Examples 1 to 9 and Comparative Examples 1 and 2 and emitted to the outside were measured by XPS, thereby obtaining the photoelectron energy distribution (Ta4f peak). Note that, for Examples 7 to 9, only the lower layer 44 was analyzed for the Ta4f spectrum.

[0176] In the analysis of the conductive film 42 by X-ray photoelectron spectroscopy (XPS), first, X-rays from an X-ray source were irradiated toward the surface of the conductive film 42 of the conductive film-coated substrate 40, and the energy distribution of photoelectrons emitted from the surface (or upper layer 46) of the conductive film 42 was measured. Next, the conductive film 42 was excavated by about 1 nm per measurement using Ar gas sputtering, and the surface of the excavated region of the conductive film 42 was measured by XPS. This measurement was repeated throughout the entire depth direction of the conductive film 42, thereby analyzing the entire depth direction of the conductive film 42. The measurement conditions for the X-ray photoelectron spectroscopy analysis were as follows: X-ray source: AlK αX-ray (1486.6 eV) X-ray irradiation area: diameter 200 μm Measurement range of photoelectron binding energy: 15 eV to 35 eV Photoelectron detection take-off angle: 45 degrees (detection depth approximately 4 to 5 nm) Step size during measurement: 0.25 eV Pass energy during measurement: 58.7 eV

[0177] The detection depth using the XPS method is approximately 4 to 5 nm. Therefore, the above-mentioned XPS analysis was able to obtain information about the interior of the conductive film 42 in the depth direction. Furthermore, from the results of the above-mentioned XPS analysis, it was determined whether the conductive film 42 had a first region in which the predetermined difference D was 0.5 or less.

[0178] The conductive films 42 in Examples 1 to 4 and Comparative Examples 1 and 2 were formed without changing the film formation conditions in each thickness direction. Therefore, each of the conductive films 42 in Examples 1 to 4 and Comparative Examples 1 and 2 was considered to have uniform characteristics that did not change in the thickness direction, except for the substrate interface region and the surface region. Therefore, whether the conductive film 42 had a first region was determined by obtaining a Ta4f spectrum at a specific depth position within the internal region as a result of a predetermined XPS measurement and analysis. More specifically, in Examples 1 to 4 and Comparative Examples 1 and 2, the conductive film 42 was determined to have a first region when the predetermined difference D was 0.5 or less at a depth position (approximately 10 to 15 nm) 10 minutes after the start of etching.

[0179] Furthermore, in Examples 5 to 9, the lower layer 44 was formed without changing the film formation conditions in each thickness direction. Therefore, each lower layer 44 was considered to have uniform characteristics that did not change in the thickness direction, except for the substrate interface region, the surface region, and the vicinity of the interface between the lower layer 44 and the upper layer 46 (layer interface region). Therefore, in Examples 5 to 9, the lower layer 44 was determined to have a first region when the predetermined difference D was 0.5 or less at a depth position 10 minutes after the start of etching of the lower layer 44 (a depth of approximately 10 to 15 nm in the lower layer), i.e., a depth within the internal region of the lower layer 44. Furthermore, the thickness of the upper layer 46 in Examples 5 and 6 was small. Therefore, the upper layer 46 was determined to have a first region when the predetermined difference D was 0.5 or less at the center position in the thickness direction. Note that, when the conductive film 42 includes a lower layer 44 and an upper layer 46, it is sufficient that at least one of the lower layer 44 and the upper layer 46 includes the first region.

[0180] 9 illustrates a spectrum including the Ta4f peak of the conductive film 42. The horizontal axis (Binding Energy) in FIG. 9 represents the binding energy of photoelectrons (unit: eV), and the vertical axis (Normalized Intensity) represents the normalized intensity. The binding energy of the Ta4f peak is generally in the range of 20 eV to 30 eV. The Ta4f peak is, for example, a Ta4f peak having a peak around 24 eV. ５／２ peak, and Ta4f peak at around 22 eV ７／２ It has two peaks.

[0181] Next, the intensity (signal counts / second) relative to the binding energy obtained by X-ray photoelectron spectroscopy (XPS) was normalized by the maximum intensity value of the Ta4f peak to obtain the normalized spectrum of Ta4f. ７／２ Since the peak is the maximum intensity value, Ta4f ７／２ The maximum intensity value of the peak was set to 1 and the Ta4f peak was normalized.

[0182] Next, the normalized Ta4f spectrum ５／２ Peak and Ta4f ７／２Based on the two peaks (the binding energy corresponding to the peak position and the normalized maximum intensity), a linear interpolation function L(Ta4f ５／２ Peak and Ta4f ７／２ A straight line L passing through the maximum values ​​of the two peaks was calculated. As shown in FIG. 9, the linear interpolation function L is Ta4f ５／２ The maximum intensity value point of the peak and Ta4f ７／２ It is a straight line connecting the point of maximum intensity value of the peak.

[0183] Next, as shown in FIG. 9, the Ta4f ５／２ Peak and Ta4f ７／２ The minimum intensity value between two peaks of the peak I ｍｉｎ The bond energy E ｍｉｎ Interpolated value of the intensity at ｍｉｎ Intensity value I of linear interpolation function L at Ｄ ) was sought.

[0184] Next, as shown in FIG. 9, the interpolated value (intensity value I Ｄ ) and the minimum intensity value I ｍｉｎ The difference D between these values ​​was calculated.

[0185] The "Difference D" column in Table 1 shows the interpolated value (intensity value I Ｄ ) and the minimum intensity value I ｍｉｎ The difference D indicates the difference D between the conductive film 42 and the lower layer 44. Note that the value of the difference D may be calculated over the entire film thickness of the internal region of the conductive film 42 (lower layer 44, upper layer 46), and the average value of the difference D in the depth direction may be used as the difference D of the conductive film 42 (lower layer 44, upper layer 46). Even if the film thickness of the upper layer 46 is very small, the average value of the difference D in the depth direction over the entire upper layer 46 may be used as the difference D of the upper layer 46.

[0186] <Sheet Resistance of Conductive Film 42> The sheet resistance of the conductive film 42 of the conductive-film-attached substrate 40 of the example and comparative example was measured by a four-terminal measurement method by contacting electrodes with the surface of the conductive film 42 (upper layer 46). The sheet resistance of the conductive film 42 of the conductive-film-attached substrate 40 of the example and comparative example was 50 Ω / □ or less, which was an appropriate sheet resistance for proper operation of the electrostatic chuck.

[0187] <Fabrication of multilayer reflective film coated substrate 20> Next, the multilayer reflective film coated substrate 20 of Examples 1 to 9 and Comparative Examples 1 and 2 were fabricated. The substrate 10 used was the same as the substrate 10 used in fabricating the conductive film coated substrate 40 of the above-mentioned Examples and Comparative Examples. As described above, a predetermined conductive film 42 was formed on the first main surface of the substrate 10 to fabricate the conductive film coated substrate 40 of Examples 1 to 9 and Comparative Examples 1 and 2. In Examples 1 to 9, the conductive film 42 formed on the substrate 10 was heated under a pressure of 1.0×10 without being exposed to the outside air. －４ The substrate was heated at 400° C. for 10 minutes under a high vacuum of 100 Pa or less. Next, a multilayer reflective film 21 was formed on the second main surface of the substrate 10 of the conductive film-coated substrate 40 of the example and comparative example.

[0188] The multilayer reflective film 21 of the multilayer reflective film coated substrate 20 of the example and comparative example was formed as follows: That is, using a Mo target and a Si target, Mo layers (low refractive index layer, thickness 2.8 nm) and Si layers (high refractive index layer, thickness 4.2 nm) were alternately laminated (40 pairs of layers) by ion beam sputtering to form the multilayer reflective film 21 on the above-mentioned substrate 10. When the multilayer reflective film 21 was formed, H ２ The gas was used as the process gas.

[0189] The atomic density (atom / nm) of hydrogen contained in the multilayer reflective film 21 of the multilayer reflective film coated substrate 20 of the example and the comparative example ３ ) was measured by dynamic SIMS (quadrupole secondary ion mass spectrometer: PHI ADEPT-1010TM, manufactured by ULVAC-PHI, Inc.). The measurement conditions were as follows: Cs ＋ The primary accelerating voltage was 1.0 kV, the primary ion irradiation area was 90 μm square, the secondary ion polarity was positive, and the detected secondary ion species was [Cs—H] ＋ The standard sample was Si. As a result, the multilayer reflective film 21 of the multilayer reflective film coated substrate 20 of the example and the comparative example both had a reflective intensity of 0.006 atom / nm ３ 0.50 atoms / nm or more ３ The multilayer reflective films 21 of the multilayer reflective film coated substrates 20 of the examples and comparative examples had low background levels during defect inspection.

[0190] After the formation of the multilayer reflective film 21, a protective film 22 (thickness: 2.5 nm) made of Ru was continuously formed on the multilayer reflective film 21 by ion beam sputtering, thereby completing the multilayer reflective film-coated substrate 20.

[0191] In this manner, the multilayer reflective film coated substrates 20 of Examples 1 to 9 and Comparative Examples 1 and 2 were manufactured.

[0192] <Measurement of the number of defects> The multilayer reflective film-coated substrates 20 of Examples 1 to 9 and Comparative Examples 1 and 2 manufactured as described above were repeatedly attached to and detached from the electrostatic chuck of an exposure device 100 times. After the multilayer reflective film-coated substrates 20 were repeatedly attached and detached 100 times, the number of defects of 1.0 μm or more on the back surface of the multilayer reflective film-coated substrates 20 was measured. The "Number of defects" column in Table 1 shows the number of defects on the back surface per substrate (conductive film-coated substrate 40) of the multilayer reflective film-coated substrates 20 of Examples 1 to 9 and Comparative Examples 1 and 2 measured in this manner.

[0193] As is clear from Table 1, the number of defects in the multilayer reflective film coated substrates 20 of Examples 1 to 9 was less than 3. In contrast, the number of defects in Comparative Example 1 exceeded 100. Furthermore, the number of defects in Comparative Example 2 exceeded 50. Therefore, it is clear that by using the multilayer reflective film coated substrates 20 of Examples 1 to 9, it is possible to suppress the generation of particles when the reflective mask 200 is attached to or detached from an electrostatic chuck in an exposure apparatus.

[0194] <Fabrication of reflective mask blank 100> A TaBN film with a thickness of 55 nm was formed by magnetron sputtering (reactive sputtering) as an absorber film 24 on the protective film 22 of the multilayer reflective film coated substrate 20 of the above-mentioned Examples 1 to 9 and Comparative Examples 1 and 2. The composition of the absorber film 24 was Ta:B:N=75:12:13 (atomic ratio), and the film thickness was 55 nm.

[0195] In this manner, the reflective mask blanks 100 of Examples 1 to 9 and Comparative Examples 1 and 2 were manufactured.

[0196] <Reflective Mask 200> Next, the reflective mask blanks 100 of Examples 1 to 9 and Comparative Examples 1 and 2 were used to manufacture the reflective masks 200 of Examples 1 to 9 and Comparative Examples 1 and 2. The manufacture of the reflective mask 200 will be described with reference to FIG.

[0197] First, as shown in Fig. 7A, a resist film 32 was formed on the absorber film 24 of the reflective mask blank 100. Then, a desired pattern such as a circuit pattern was drawn (exposed) on the resist film 32, and the resist film 32 was further developed and rinsed to form a predetermined resist pattern 32a (Fig. 7B). Next, the absorber film 24 (TaBN film) was exposed to light using the resist pattern 32a as a mask. ２ Dry etching was performed using a gas to form an absorber pattern 24a (FIG. 7C), after which the resist pattern 32a was removed (FIG. 7D).

[0198] Finally, wet cleaning was performed using deionized water (DIW), and the reflective masks 200 of Examples 1 to 9 and Comparative Examples 1 and 2 were manufactured.

[0199] <Manufacturing of Semiconductor Device> The reflective masks 200 of Examples 1 to 9 and Comparative Examples 1 and 2 were set in an EUV scanner, and EUV exposure was performed in a hydrogen atmosphere on a wafer having a processing film and a resist film formed on a semiconductor substrate 60, which was the target of transfer. Then, by developing this exposed resist film, a resist pattern was formed on the semiconductor substrate 60 on which the processing film was formed.

[0200] The reflective masks 200 of Examples 1 to 9 include the predetermined conductive film 42 of this embodiment, which is thought to suppress hydrogen diffusion within the conductive film 42. Therefore, by using the reflective masks 200 of Examples 1 to 9, it was possible to form a fine, highly accurate transfer pattern (resist pattern) on the semiconductor substrate 60 (transferred substrate). On the other hand, the conductive film 42 of the reflective masks 200 of Comparative Examples 1 and 2 is not the predetermined conductive film 42 of this embodiment. Therefore, when the reflective masks 200 of Comparative Examples 1 and 2 were used, the generation of particles during electrostatic chucking and detachment of the reflective mask in the exposure apparatus could not be suppressed. Therefore, when the reflective masks 200 of Comparative Examples 1 and 2 were used, it was not possible to form a fine, highly accurate transfer pattern (resist pattern) on the semiconductor substrate 60 (transferred substrate) compared to Examples 1 to 9.

[0201] When semiconductor devices were manufactured using the reflective masks 200 of Examples 1 to 9, the resist pattern was transferred to the film to be processed by etching, and various processes such as forming an insulating film or a conductive film, introducing a dopant, or annealing were carried out, thereby making it possible to manufacture semiconductor devices having the desired characteristics with a high yield.

[0202]

[0203] REFERENCE SIGNS LIST 10 Substrate 20 Substrate with multilayer reflective film 21 Multilayer reflective film 22 Protective film 24 Absorber film 24a Absorber pattern 25 Etching mask film 32 Resist film 32a Resist pattern 40 Substrate with conductive film 42 Conductive film 44 Lower layer 46 Upper layer 50 EUV exposure apparatus 51 EUV light generation unit 52 Laser light source 53 Tin droplet generation unit 54 Capture unit 55 Collector 56 Irradiation optical system 57 Projection optical system 58 Reticle stage 59 Wafer stage 60 Semiconductor substrate 100 Reflective mask blank 200 Reflective mask

Claims

1. A substrate and a conductive film formed on a first main surface of the substrate, wherein the conductive film has, in a spectrum of Ta4f normalized by a maximum intensity value of a Ta4f peak obtained by analyzing the conductive film by X-ray photoelectron spectroscopy, a first region including a difference D between a minimum intensity value between a Ta4f peak and a Ta4f peak and an interpolated value of intensity at a binding energy of the minimum intensity value on a linear interpolation function obtained by linear interpolation based on the Ta4f peak and the Ta4f peak being 0.5 or less. ５／２ peak and Ta4f ７／２ peak and the Ta4f ５／２ peak and the Ta4f ７／２ peak, and the difference D between the interpolated value of the intensity at the binding energy of the minimum intensity value on the linear interpolation function obtained by linear interpolation based on the Ta4f peak and the Ta4f peak is 0.5 or less. A substrate with a conductive film, characterized in that it includes such a first region.

2. The first region of the conductive film contains tantalum and at least one of nitrogen and boron, and in the first region, the total content of tantalum, nitrogen and boron is 95 atomic% or more. The substrate with a conductive film according to claim 1, characterized in that.

3. The first region of the conductive film contains 95 atomic% or more of tantalum. The substrate with a conductive film according to claim 1 or 2, characterized in that.

4. The first region of the conductive film contains 15 atomic% or more of nitrogen. The substrate with a conductive film according to claim 1 or 2, characterized in that.

5. The conductive film includes a lower layer formed on the first main surface of the substrate and an upper layer formed on the lower layer. At least one of the lower layer and the upper layer has the first region. The substrate with a conductive film according to claim 1 or 2, characterized in that.

6. The upper layer contains more oxygen than the lower layer. The substrate with a conductive film according to claim 5, characterized in that.

7. A multilayer reflective film in which a high refractive index layer and a low refractive index layer are alternately laminated is formed on the second main surface facing the first main surface of the substrate with a conductive film according to claim 1 or 2. A substrate with a multilayer reflective film, characterized in that.

8. An absorber film is formed on the multilayer reflective film of the substrate with a multilayer reflective film according to claim 7. A reflective mask blank, characterized in that.

9. A reflective mask having an absorber pattern obtained by etching the absorber film of the reflective mask blank according to claim 8.

10. A method for manufacturing a semiconductor device, comprising a step of transferring the absorber pattern to an object to be transferred by exposure using the reflective mask according to claim 9.

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