Substrate with conductive film, reflective mask blank, reflective mask, and semiconductor device production method

Abstract

Provided is a substrate with a conductive film which can inhibit changes in flatness in a reflective mask and a reflective mask blank for EUV lithography having a conductive film.　This substrate with a conductive film includes a substrate having two main surfaces, and a conductive film disposed on one of the main surfaces of the substrate, and is characterized in that: the conductive film includes an outermost layer disposed on an outermost surface on the reverse side of the conductive film from the substrate, and a conductive layer disposed between the outermost layer and the substrate; the outermost layer includes a metal (M), boron (B), and oxygen (O); and a B1s narrow spectrum of the outermost layer obtained through analysis with X-ray photoelectron spectroscopy has a maximum peak at a binding energy of 190-195 eV.

Description

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

[0001] The present invention relates to a substrate with a conductive film for use in EUV lithography, a reflective mask blank, a reflective mask, and a method for manufacturing a 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 film pattern by photolithography 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 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 a conductive film formed on the surface opposite to the surface on which the multilayer reflective film is formed. Patent Document 1 describes that the conductive film is made of a material that contains tantalum and is substantially free of hydrogen. Patent Document 1 also describes that the multilayer reflective film-coated substrate includes a hydrogen penetration suppression film between the glass substrate and the conductive film, which suppresses hydrogen from penetrating from the glass substrate into the conductive film.

[0006] Patent Document 2 describes a substrate for a photolithography mask that includes a coating deposited on the rear surface of the substrate, wherein the coating includes at least one conductive layer, and the thickness of the at least one layer is less than 30 nm.

[0007] JP 2013-225662 A JP 2014-532313 A

[0008] The defect quality requirements for reflective mask blanks and reflective masks are becoming stricter every year. When manufacturing reflective mask blanks and semiconductor devices using reflective masks, the reflective mask blanks and reflective masks are repeatedly attached to and detached from an electrostatic chuck. During this process, friction occurs between the conductive film of the reflective mask blank or reflective mask and the electrostatic chuck. Therefore, after detaching the reflective mask blank or reflective mask from the electrostatic chuck, the surface of the conductive film is usually chemically cleaned using an acid or alkali. Materials containing tantalum (Ta), which has high chemical resistance and abrasion resistance, have been attracting attention as conductive film materials.

[0009] Furthermore, in recent years, the level of pattern position accuracy required for transfer masks such as reflective masks has become particularly strict. In particular, in the case of reflective masks for EUV lithography, the required level of pattern position accuracy is even stricter because they are used for the purpose of forming extremely fine patterns compared to conventional techniques. One factor for achieving high pattern position accuracy is to improve the flatness of a reflective mask blank, which serves as a master for producing a reflective mask.

[0010] In Patent Document 1, the conductive film is made of a material that contains tantalum and is substantially free of hydrogen, and a hydrogen penetration suppression film is provided between the glass substrate and the conductive film to suppress the penetration of hydrogen from the glass substrate into the conductive film, thereby making it possible to obtain a reflective mask blank in which changes in flatness over time are suppressed.

[0011] In EUV exposure apparatuses that transfer integrated circuit patterns onto semiconductor substrates using EUV light reflected by a reflective mask, a high vacuum is generally required within the optical system chamber because EUV light is strongly absorbed by gas molecules. However, even in a high vacuum, impurities such as moisture and hydrocarbons cannot be completely eliminated. When these impurities are exposed to EUV light, carbon films and other impurities deposit on the mirror surfaces of the irradiation optical system, resulting in a decrease in reflectivity. To prevent such contamination, EUV exposure apparatuses perform exposure in a hydrogen atmosphere, which has high transparency to EUV light. It has been discovered that repeated use of a reflective mask in such a hydrogen atmosphere for semiconductor device fabrication can result in hydrogen penetration from the surface of the conductive film, causing a problem of changing the flatness of the reflective mask.

[0012] The present invention has been made under these circumstances, and aims to provide a reflective mask blank and a reflective mask having a conductive film, which can suppress changes in flatness. Another aim of the present invention is to provide a substrate with a conductive film for manufacturing a reflective mask blank and a reflective mask that solves the above problems. Another aim of the present invention is to provide a method for manufacturing a high-precision semiconductor device by using the above reflective mask.

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

[0014] (Configuration 1) Configuration 1 is a substrate with a conductive film, comprising: a substrate having two main surfaces; and a conductive film disposed on one of the main surfaces of the substrate, wherein the conductive film includes an outermost layer disposed on the outermost surface of the conductive film opposite the substrate, and a conductive layer disposed between the outermost layer and the substrate, the outermost layer containing metal (M), boron (B), and oxygen (O), and wherein a narrow spectrum of B1s obtained by X-ray photoelectron spectroscopy analysis of the outermost layer has a maximum peak at a binding energy of 190 eV or more and 195 eV or less.

[0015] (Configuration 2) Configuration 2 is the substrate with a conductive film according to configuration 1, characterized in that the detection depth of the outermost layer by X-ray photoelectron spectroscopy is about 4 to 5 nm.

[0016] (Configuration 3) Configuration 3 is the substrate with a conductive film according to Configuration 1 or 2, wherein the outermost layer does not have a peak at a binding energy of 185 eV or more and less than 190 eV in a narrow B1s spectrum obtained by analyzing the outermost layer by X-ray photoelectron spectroscopy.

[0017] (Configuration 4) Configuration 4 is the substrate with a conductive film according to any one of configurations 1 to 3, characterized in that the boron (B) content of the outermost layer is 0.5 to 25 atomic %.

[0018] (Configuration 5) Configuration 5 is the substrate with a conductive film according to any one of configurations 1 to 4, wherein the conductive layer contains the metal (M) and boron (B).

[0019] (Configuration 6) Configuration 6 is the substrate with a conductive film according to any one of Configurations 1 to 5, wherein the conductive layer has a maximum peak at a binding energy of 185 eV or more and less than 190 eV in a narrow B1s spectrum obtained by analyzing the conductive layer with X-ray photoelectron spectroscopy.

[0020] (Configuration 7) Configuration 7 is the substrate with a conductive film according to any one of configurations 1 to 6, wherein the metal (M) is at least one selected from Ta, Cr, Pt, Au, Rh, Ru, Ir, and Hf.

[0021] (Configuration 8) Configuration 8 is a reflective mask blank including: a substrate with a conductive film according to any one of Configurations 1 to 7; a multilayer reflective film disposed on the other main surface of the substrate; and an absorber film disposed on the multilayer reflective film.

[0022] (Configuration 9) Configuration 9 is a reflective mask including an absorber pattern formed in the absorber film of the reflective mask blank of configuration 8.

[0023] (Configuration 10) Configuration 10 is a method for manufacturing a semiconductor device, characterized by comprising a step of performing a lithography process using an exposure apparatus with the reflective mask of configuration 9 to form a transfer pattern on a transfer target.

[0024] The present invention can provide a reflective mask blank and a reflective mask for EUV lithography that have a conductive film and that can suppress changes in flatness. The present invention can also provide a substrate with a conductive film for manufacturing a reflective mask blank and a reflective mask that solves the above problems. Furthermore, by using the reflective mask of the present invention, a method for manufacturing a high-precision semiconductor device can be provided.

[0025] FIG. 1 is a cross-sectional view schematically showing an example of the configuration of a conductive film-coated substrate of this embodiment. FIG. 2 is a cross-sectional view schematically showing an example of the configuration of a conductive film-coated substrate (multilayer reflective film-coated substrate) of this embodiment. FIG. 3 is a cross-sectional view schematically showing an example of the configuration of a conductive film-coated substrate (multilayer reflective film-coated substrate) of this embodiment. FIG. 4 is a cross-sectional view schematically showing an example of the configuration of a reflective mask blank 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 an example of a method for manufacturing a reflective mask of this embodiment. FIG. 7 is a schematic diagram showing an example of an EUV exposure apparatus. FIG. 8 is a view showing B1s narrow spectra obtained by analyzing the conductive films of the conductive film-coated substrates of Example 1 and Comparative Example 1 of this embodiment by X-ray photoelectron spectroscopy.

[0026] 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.

[0027] 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 (second 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 (second 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. 2 and 3 ) having a multilayer reflective film 21 formed on the other main surface (first main surface or front surface), and a reflective mask blank 100 (see FIGS. 4 and 5 ) having an absorber film 24 formed thereon. In this specification, the conductive film 42 may also be referred to as a back surface conductive film.

[0028] Fig. 2 shows an example of a multilayer reflective film-coated substrate 20. A multilayer reflective film 21 is formed on a first main surface of a substrate 10 of the multilayer reflective film-coated substrate 20 shown in Fig. 2. A conductive film 42 is formed on a second main surface (rear surface) of the substrate 10 of the multilayer reflective film-coated substrate 20 shown in Fig. 2. The multilayer reflective film-coated substrate 20 shown in Fig. 2 is a type of conductive film-coated substrate 40, since it includes the conductive film 42 on the second main surface (rear surface) of the substrate 10.

[0029] Fig. 3 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. 3. A conductive film 42 is formed on the second 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 second main surface (rear surface) of the substrate 10.

[0030] Fig. 4 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. 4 has a multilayer reflective film 21, a protective film 22, and an absorber film 24. The reflective mask blank 100 shown in Fig. 4 also has a conductive film 42 on its second main surface (rear surface). Therefore, the reflective mask blank 100 shown in Fig. 4 is a type of substrate 40 with a conductive film.

[0031] Fig. 5 is a cross-sectional schematic diagram showing another example of a reflective mask blank 100 of this embodiment. The reflective mask blank 100 shown in Fig. 5 has an etching mask film 25 on an absorber film 24. When using a reflective mask blank 100 having an etching mask film 25, the etching mask film 25 may be peeled off after a transfer pattern is formed in the absorber film 24, as described below. The reflective mask blank 100 of this embodiment also includes a conductive film 42 on its back surface. Therefore, the reflective mask blank 100 shown in Fig. 5 is a type of substrate 40 with a conductive film.

[0032] Furthermore, in the reflective mask blank 100 shown in Figure 4 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 forming the reflective mask blank 100 as an absorber film 24 with an etching mask function.

[0033] 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.

[0034] 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.

[0035] [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.

[0036] The substrate 10 preferably has a low thermal expansion coefficient within the range of 0±5 ppb / °C to prevent distortion of the transferred pattern due to heat during exposure to EUV light. 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.

[0037] The main surface (first main surface) of the substrate 10 on which a transfer pattern (the absorber pattern 24a described below) is formed is preferably processed to increase its flatness. Increasing the flatness of the main surface of the substrate 10 can improve the positional accuracy and transfer accuracy of the pattern. For example, in the case of EUV exposure, the flatness in a 132 mm × 132 mm area of ​​the first main surface is preferably 0.1 μm or less, more preferably 0.05 μm or less, and particularly preferably 0.03 μm or less. The second main surface (rear surface) opposite the side on which the transfer pattern is formed is the surface fixed to the exposure apparatus by an electrostatic chuck. In a 142 mm × 142 mm area of ​​the rear surface, the flatness is 0.1 μm or less, more preferably 0.05 μm or less, and particularly preferably 0.03 μm or less. In this specification, flatness is a value representing the warpage (deformation) of the surface indicated by TIR (Total Indicated Reading). The flatness (TIR) ​​is the absolute value of the difference in height between the highest point on the surface of the substrate 10 above the focal plane, which is determined by the least squares method based on the surface of the main surface of the substrate 10, and the lowest point on the surface of the substrate 10 below the focal plane.

[0038] In the case of EUV exposure, the surface roughness of the first main surface of the substrate 10 on which the transfer pattern is formed is preferably 0.1 nm or less in terms of root mean square roughness (Rq). The surface roughness can be measured using an atomic force microscope.

[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] [Substrate 40 with Conductive Layer] Next, the substrate 40 with conductive layer of this embodiment will be described.

[0041] 1, 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 (second 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. As shown in FIG. 1, the conductive film 42 of the conductive film-coated substrate 40 of this embodiment includes an outermost layer 46 and a conductive layer 44.

[0042] 1 , the outermost layer 46 included in the conductive film 42 of the conductive film-coated substrate 40 of this embodiment is disposed on the outermost surface of the conductive film 42 on the side opposite to the substrate 10. By including the predetermined outermost layer 46 in the conductive film 42 of the conductive film-coated substrate 40 of this embodiment, it is possible to prevent external hydrogen from being absorbed into the conductive film 42.

[0043] The outermost layer 46 contains metal (M), boron (B), and oxygen (O).

[0044] The present inventors have found that the film stress of a conductive film 42 containing tantalum as the metal (M) changes as hydrogen is absorbed into the conductive film 42. Furthermore, the present inventors have found that even in the case of a conductive film 42 containing a metal (M) other than tantalum, the volume of the conductive film 42 changes as hydrogen is absorbed into the conductive film 42, and therefore the film stress of the conductive film 42 may change. The change in film stress of the conductive film 42 causes a problem in that the flatness of the reflective mask blank 100 changes. Furthermore, a problem occurs in that the position of the pattern of the reflective mask 200 shifts over time after the reflective mask 200 is fabricated.

[0045] The inventors have found that the hydrogen incorporated into the conductive film 42 is hydrogen present outside the reflective mask 200 in an EUV exposure environment. The inventors discovered that by including a predetermined outermost layer 46 in the conductive film 42 of the conductive film-equipped substrate 40 of this embodiment, it is possible to prevent hydrogen present outside the reflective mask 200 from being incorporated into the conductive film 42 of the reflective mask 200 in an EUV exposure environment, leading to the development of the conductive film-equipped substrate 40 of this embodiment. By manufacturing a reflective mask blank 100 and a reflective mask 200 using the conductive film-equipped substrate 40 of this embodiment, it is possible to prevent hydrogen from being incorporated into the conductive film 42 of the reflective mask blank 100 and the reflective mask 200. Therefore, it is possible to prevent changes in the film stress of the conductive film 42 of the reflective mask blank 100 and the reflective mask 200. That is, the conductive film-equipped substrate 40 of this embodiment can prevent changes in the flatness of the reflective mask blank 100 and the reflective mask 200. As a result, it is possible to prevent the pattern of the reflective mask 200 from shifting in position over time after the reflective mask 200 is manufactured.

[0046] The metal (M) contained in the outermost layer 46 is preferably at least one selected from Ta, Cr, Pt, Au, Rh, Ru, Ir, and Hf. The metal (M) contained in the outermost layer 46 is more preferably at least one selected from Ta and Cr. When the metal (M) contained in the outermost layer 46 is a predetermined element, it is possible to more reliably suppress external hydrogen from being taken into the conductive film 42.

[0047] In the conductive film-coated substrate 40 of this embodiment, the boron (B) content of the outermost layer 46 is preferably 0.5 to 25 atomic %, and more preferably 1 to 15 atomic %. When the boron (B) content of the outermost layer 46 is within a predetermined range, the function of the outermost layer 46 to suppress hydrogen uptake can be further ensured.

[0048] The metal (M) content of the outermost layer 46 is preferably 10 to 70 atomic %, more preferably 20 to 60 atomic %, and the O content of the outermost layer 46 is preferably 20 to 80 atomic %, more preferably 30 to 70 atomic %.

[0049] According to research by the present inventors, a film containing metal (M), boron (B), and oxygen (O) (e.g., a TaBO film and a TaBON film) has a higher hydrogen absorption suppression function than a film containing metal (M) and oxygen (O) (e.g., a TaO film). Therefore, by including boron (B) in the outermost layer 46, the hydrogen absorption suppression function of the conductive film 42 can be improved. The ratio of boron (B) to oxygen (O) in the outermost layer 46 is preferably B:O=1:20 to 1:70, and more preferably 1:30 to 1:60.

[0050] In order to more reliably prevent external hydrogen from being taken into the conductive film 42, the material of the outermost layer 46 is preferably TaBO or TaBON.

[0051] When the material of the outermost layer 46 is TaBO, the composition of tantalum (Ta), boron (B), and oxygen (O) is preferably 15 to 60 atomic % of Ta, 0.5 to 25 atomic % of B, and 20 to 80 atomic % of O, and more preferably 25 to 50 atomic % of Ta, 1 to 15 atomic % of B, and 30 to 70 atomic % of O. Note that the material of the outermost layer 46 may contain elements other than Ta, B, and O to the extent that the effects of this embodiment are not affected.

[0052] When the material of the outermost layer 46 is TaBON, the composition of tantalum (Ta), boron (B), oxygen (O), and nitrogen (N) is preferably 20 to 55 atomic % of Ta, 0.5 to 25 atomic % of B, 25 to 75 atomic % of O, and 0.5 to 40 atomic % of N, and more preferably 25 to 50 atomic % of Ta, 1 to 15 atomic % of B, 30 to 70 atomic % of O, and 1 to 30 atomic % of N. Note that the material of the outermost layer 46 may contain elements other than Ta, B, O, and N, as long as the effects of this embodiment are not affected.

[0053] When the material (TaBO or TaBON) of the outermost layer 46 has the above-described composition, hydrogen present outside can be more effectively prevented from being taken into the conductive film 42 .

[0054] The outermost layer 46 has a narrow B1s spectrum obtained by X-ray photoelectron spectroscopy (XPS) analysis, which has a maximum peak at a binding energy of 190 eV or more and 195 eV or less. In XPS, electrons of atoms contained in a substance are excited by X-rays and emitted to the outside as photoelectrons. By measuring the energy (binding energy) of the emitted photoelectrons, the energy distribution (spectrum) of the photoelectrons can be obtained.

[0055] The outermost layer 46 included in the conductive film 42 of the conductive film-coated substrate 40 of this embodiment contains boron (B). A narrow B1s spectrum of boron (B) in the outermost layer 46 can be obtained by detecting photoelectrons with a binding energy range of 180 eV to 205 eV using the XPS method. The inventors have found that when the narrow B1s spectrum of the outermost layer 46 has a maximum peak at a binding energy of 190 eV or more and 195 eV or less, it is possible to suppress the incorporation of external hydrogen into the conductive film 42. The peak in the B1s narrow spectrum at a binding energy of 190 eV or more and 195 eV or less is thought to be a peak resulting from B-O bonds in the outermost layer 46. Therefore, it is presumed that the hydrogen suppression effect of the outermost layer 46 is high when there are many B-O bonds in the outermost layer 46.

[0056] In the conductive film-formed substrate 40 of this embodiment, the outermost layer 46 preferably does not have a peak at a binding energy of 185 eV or more and less than 190 eV in the B1s narrow spectrum obtained by analysis by X-ray photoelectron spectroscopy. The peak at a binding energy of 185 eV or more and less than 190 eV in the B1s narrow spectrum is thought to be a peak caused by B-M bonds in the outermost layer 46. Therefore, when there are few or no B-M bonds in the outermost layer 46, it is presumed that the hydrogen suppression effect of the outermost layer 46 is high.

[0057] It is known that the energy (binding energy) of photoelectrons emitted to the outside in the XPS method varies depending on the film thickness and film formation conditions, and does not have a unique relationship with the composition. Specific examples of analysis methods using X-ray photoelectron spectroscopy (XPS) will be described later.

[0058] In the conductive film-coated substrate 40 of this embodiment, the thickness of the outermost layer 46 can be set to 2 nm to 30 nm, and can be set to 2 nm to 20 nm. The thickness of the outermost layer 46 is preferably set to 2 nm to 10 nm, more preferably set to 3 nm to 8 nm, and even more preferably set to 4 nm to 6 nm. By setting the thickness of the outermost layer 46 within the specified range, the function of suppressing hydrogen uptake by the outermost layer 46 can be more reliably achieved, while the conductive film 42 can function as an electrostatic chuck.

[0059] 1 , the conductive layer 44 included in the conductive film 42 of the conductive-film-coated substrate 40 of this embodiment is disposed between the outermost layer 46 and the substrate 10. By including the predetermined conductive layer 44 in the conductive film 42, the conductive film 42 can function as an electrostatic chuck to facilitate the fixation of the reflective mask 200.

[0060] The conductive layer 44 of the conductive film-coated substrate 40 of this embodiment preferably contains metal (M) and boron (B). By making the conductive layer 44 from a material containing boron, a conductive film 42 having wear resistance and chemical resistance can be obtained. The conductive layer 44 can also contain nitrogen (N).

[0061] The metal (M) contained in the conductive layer 44 is preferably at least one selected from Ta, Cr, Pt, Au, Rh, Ru, Ir, and Hf, as in the outermost layer 46. Furthermore, the metal (M) is more preferably at least one selected from Ta and Cr, as in the outermost layer 46. The metal (M) contained in the conductive layer 44 may be a different type of element from the metal (M) contained in the outermost layer 46. However, to facilitate the formation of the conductive layer 44 and the outermost layer 46, the metal (M) contained in the conductive layer 44 is preferably the same type of element as the metal (M) contained in the outermost layer 46. By making the conductive film 42 from a material containing a predetermined metal (M), the electrostatic chuck can operate appropriately, resulting in a low sheet resistance.

[0062] The metal (M) content of the conductive layer 44 is preferably 60 to 95 atomic %, more preferably 70 to 90 atomic %, and the boron (B) content of the conductive layer 44 is preferably 2 to 40 atomic %, more preferably 5 to 30 atomic %.

[0063] The metal (M) contained in the conductive layer 44 more preferably contains Ta. Specific examples of the Ta-containing material of the conductive layer 44 include Ta, TaB, TaBO, TaBN, TaBON, TaO, TaON, and TaN. TaB is preferably used as the Ta-containing material of the conductive layer 44. By forming the conductive layer 44 from a material containing tantalum and boron, a conductive film 42 having wear resistance and chemical resistance can be obtained. For the same reason, the total content of oxygen (O) and nitrogen (N) contained in the conductive layer 44 is preferably 30 atomic % or less, and more preferably 20 atomic % or less.

[0064] When the material of the conductive layer 44 is TaB, the composition of tantalum (Ta) and boron (B) is preferably 75 to 95 atomic % of Ta and 5 to 25 atomic % of B, and more preferably 80 to 90 atomic % of Ta and 10 to 20 atomic % of B. Note that the material of the conductive layer 44 may contain elements other than Ta and B as long as the effects of this embodiment are not affected.

[0065] The composition of the conductive layer 44 does not need to be constant in the film thickness direction. The conductive layer 44 can be a compositionally graded film whose composition changes in the film thickness direction. Furthermore, the conductive film 42 including the outermost layer 46 can also be a compositionally graded film whose composition changes in the film thickness direction.

[0066] The conductive layer 44 may also be formed as two or more layers. In this case, the conductive layer 44 may include an upper layer on the outermost layer 46 side and a lower layer other than the upper layer. The lower layer may have the same configuration as the conductive layer 44 described above. The upper layer may include a metal (M) and nitrogen (N). From the viewpoint of continuous film formation of the conductive layer 44, it is preferable that the metal (M) of the upper layer is the same metal as at least one of the lower layer and the outermost layer 46. It is also preferable that the upper layer further includes boron (B). Specifically, TaBN and TaBON may be used as materials for the upper layer.

[0067] When the upper layer is made of TaBN, the composition is preferably 15 to 90 atomic % Ta, 0.5 to 25 atomic % B, and 5 to 50 atomic % N, and more preferably 25 to 80 atomic % Ta, 1 to 15 atomic % B, and 10 to 40 atomic % N. When the upper layer is made of TaBON, the composition can be the same as that of the outermost layer 46 described above. The film thickness of the upper layer is preferably 1 to 15 nm, and more preferably 2 to 10 nm.

[0068] The thickness of the conductive layer 44 can be appropriately controlled within a range that allows an appropriate sheet resistance to be obtained. The thickness of the conductive layer 44 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 thickness of the conductive layer 44 is preferably 200 nm or less, and more preferably 100 nm or less.

[0069] The conductive layer 44 of the conductive film-coated substrate 40 of this embodiment preferably has a maximum peak at a bond energy of 185 eV or more but less than 190 eV in the narrow B1s spectrum obtained by X-ray photoelectron spectroscopy (XPS). The peak at a bond energy of 185 eV or more but less than 190 eV in the narrow B1s spectrum is believed to be a peak due to B-M bonds in the conductive layer 44. When the conductive layer 44 contains many B-M bonds, 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 can be increased, even if a thin outermost layer 46 is present on the surface of the conductive film 42. This can suppress misalignment of the reflective mask 200 during pattern transfer.

[0070] The above-mentioned analysis by X-ray photoelectron spectroscopy (XPS method) can be carried out as follows.

[0071] X-ray photoelectron spectroscopy (XPS) analysis of the conductive film 42 can be performed in two ways: surface analysis and internal analysis. In surface analysis, X-rays from an X-ray source are irradiated toward the surface of the conductive film-coated substrate 40 (conductive film 42), and the energy distribution of photoelectrons emitted from the outermost layer 46 of the conductive film 42 can be measured. In internal analysis, the conductive film 42 is excavated by Ar gas sputtering to a depth that allows analysis of the conductive layer 44 (e.g., approximately 10 nm), and X-rays are irradiated onto the surface of the excavated region of the conductive film 42 (conductive layer 44), thereby measuring the energy distribution of photoelectrons emitted from the conductive layer 44 of the conductive film 42. The excavation depth for internal analysis can be determined depending on the film thickness of the outermost layer 46. For example, if the film thickness of the outermost layer 46 is 20 nm, the excavation depth for internal analysis can be approximately 30 nm. Measurements for X-ray photoelectron spectroscopy (XPS) analysis are preferably performed under the following measurement conditions. (XPS measurement conditions) X-ray source: AlK α ray (1486.6 eV) Photoelectron detection area: diameter 200 μm Measurement range of photoelectron binding energy: 180 eV to 205 eV Photoelectron detection take-off angle: 45 degrees (detection depth approximately 4 to 5 nm) Step size during measurement: 0.25 eV

[0072] Under the measurement conditions for the XPS method described above, the detection depth is approximately 4 to 5 nm, so in surface analysis, most of the photoelectrons analyzed by the XPS method are thought to be photoelectrons emitted from the outermost layer 46. Therefore, the information obtained by surface analysis can be thought of as information on the outermost layer 46. Furthermore, in internal analysis in which the conductive film 42 is dug by Ar gas sputtering to a depth of, for example, approximately 10 nm, most of the photoelectrons analyzed by the XPS method are thought to be photoelectrons emitted from the conductive layer 44. Therefore, the information obtained by internal analysis can be thought of as information on the conductive layer 44.

[0073] In this specification, a peak obtained by analysis using X-ray photoelectron spectroscopy (XPS) refers to a peak obtained when the spectrum of photoelectron binding energies measured as described above (signal intensity relative to a predetermined range of binding energies) is illustrated, and the signal intensity of the peak obtained by subtracting the background from the measured spectrum can be at least twice the magnitude of the background noise near the peak (the amplitude of the oscillation of the noise signal intensity). The binding energy of the peak can be the binding energy that indicates the maximum value of the peak obtained by subtracting the background from the measured spectrum. Furthermore, the signal intensity and binding energy of the peak can be determined using known curve fitting techniques.

[0074] 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. The sheet resistance of the conductive film 42 can be adjusted by adjusting the composition and film thickness of the conductive film 42 (particularly the conductive layer 44).

[0075] The thickness of the conductive film 42 can be appropriately controlled within a range that allows the above-mentioned sheet resistance to be obtained. The thickness of the conductive film 42 is preferably 10 nm or more, and more preferably 20 nm or more. From the viewpoint of reducing surface roughness, the thickness of the conductive film 42 is preferably 210 nm or less, and more preferably 100 nm or less.

[0076] The conductive film 42 (the conductive layer 44 and the outermost layer 46) is preferably formed by sputtering using a sputtering target containing the metal that is the material of the conductive film 42. Specifically, the substrate 10 is preferably rotated on a horizontal plane with the deposition surface of the substrate 10 facing upward. The substrate 10 is preferably positioned such that its central axis is offset from a line that passes through the center of the sputtering target and is parallel to the central axis of the substrate 10. The conductive film 42 (the conductive layer 44 and the outermost layer 46) is preferably formed by sputtering a sputtering target that faces the deposition surface at a predetermined angle. The predetermined angle is preferably an inclination angle of the sputtering target of 5 degrees or more and 30 degrees or less. 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 (the conductive layer 44 and the outermost layer 46) can be obtained.

[0077] When a rare gas is used as the gas for sputtering film formation, it is believed that by using krypton (Kr) or xenon (Xe), which have a larger atomic weight than argon (Ar), the actual contact area of ​​the surface of the conductive film 42 can be increased, and as a result, the static friction coefficient of the conductive film 42 can be increased. This increases the frictional force (static friction coefficient) between the surface of the conductive film 42 and the chucking and holding surface of the electrostatic chuck of the exposure tool, and suppresses misalignment of the reflective mask 200 during pattern transfer.

[0078] <<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 layer 44 and the outermost layer 46 .

[0079] The conductive film-coated substrate 40, the multilayer reflective film-coated substrate 20, and the reflective mask blank 100 of this embodiment preferably include a hydrogen penetration-inhibiting film as an intermediate layer between the glass substrate serving as the substrate 10 and the conductive layer 44 to inhibit hydrogen from penetrating from the substrate 10 (glass substrate) into the conductive layer 44. The presence of the hydrogen penetration-inhibiting film can inhibit hydrogen from being taken into the conductive layer 44, and can suppress an increase in compressive stress of the conductive layer 44.

[0080] 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 penetration from the substrate 10 (glass substrate) into the conductive film 42. The hydrogen penetration inhibiting film may be a thin film having the same characteristics as the outermost layer 46 described above. That is, like the outermost layer 46, the hydrogen penetration inhibiting film may be a film whose B1s narrow spectrum obtained by analysis by X-ray photoelectron spectroscopy has a maximum peak at a binding energy of 190 eV or more and 195 eV or less. Furthermore, the hydrogen penetration inhibiting film may be a thin film having the same material and / or composition as the outermost layer 46.

[0081] In order to reliably suppress the penetration of hydrogen into the conductive film 42, the material of the hydrogen penetration suppression film is preferably a material containing tantalum and oxygen. Preferred materials for the hydrogen penetration suppression film include TaO, TaON, TaBO, and TaBON. The material of the hydrogen penetration suppression film is more preferably a material selected from TaO, TaON, TaBO, and TaBON, and has an oxygen content of 50 atomic % or more. The hydrogen penetration suppression film can be a single layer of these materials, or may be a film consisting of multiple layers or a compositionally graded film.

[0082] The thickness of the hydrogen penetration inhibiting film is preferably 1 nm or more, more preferably 5 nm or more, and even more preferably 10 nm or more. If the thickness of the hydrogen penetration inhibiting film is less than 1 nm, the hydrogen penetration inhibiting film is too thin and the effect of preventing hydrogen penetration cannot be expected. Furthermore, if the thickness of the hydrogen penetration inhibiting film is less than 1 nm, it is not easy to form a film with a substantially uniform film thickness and a substantially uniform film composition on the main surface of the substrate 10 (glass substrate) even by sputtering.

[0083] It is preferable that the hydrogen penetration suppression film is formed in an area that is the same as or larger 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).

[0084] [Multilayer Reflective Film Coated Substrate 20] Next, the multilayer reflective film coated substrate 20 of this embodiment will be described. Figures 2 and 3 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 second main surface (rear surface) of the multilayer reflective film coated substrate 20 shown in Figures 2 and 3. The multilayer reflective film coated substrate 20 having the conductive film 42 is a type of conductive film coated substrate 40 of this embodiment.

[0085] <Multilayer reflective film 21>

[0086] In the multilayer reflective film coated substrate 20 of the embodiment, a multilayer reflective film 21 is disposed on the first main surface of the substrate 10. The multilayer reflective film 21 provides the reflective mask 200 with the function of reflecting EUV light. The multilayer reflective film 21 is a multilayer film in which layers each containing elements with different refractive indices as main components are periodically stacked.

[0087] 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 40 to 60 cycles.

[0088] 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 is easily oxidized, resulting in a decrease in 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.

[0089] 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 40 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 are preferably ruthenium (Ru) layers, and the high refractive index layers are preferably 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).

[0090] 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.

[0091] Methods for forming the multilayer reflective film 21 are 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 multilayer film described above, for example, a Si film having a thickness of about 4 nm is first deposited on the substrate 10 using a Si target by ion beam sputtering, and then a Mo film having a thickness of about 3 nm is deposited using a Mo target. This constitutes one period, and 40 to 60 periods are stacked to form the multilayer reflective film 21 (the top layer on the outermost surface is a Si film). Note that, although 60 periods requires more steps than 40 periods, the reflectivity for EUV light can be increased.

[0092] <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 opposite the substrate 10.

[0093] A protective film 22 (see FIG. 3 ) 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. 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.

[0094] 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.

[0095] The protective film 22 may be made of, for example, Ru, Rh, Ru-(Nb, Rh, Zr, Y, B, Ti, La, Mo), Si-(Ru, Rh, Cr, B), or Si, Zr, Nb, La, or B. Among these, the use of a material containing ruthenium (Ru) improves the reflectivity characteristics of the multilayer reflective film 21. Specifically, the protective film 22 is preferably made of 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.

[0096] 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.

[0097] [Reflective Mask Blank 100] Next, the reflective mask blank 100 of this embodiment will be described. Fig. 4 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 second main surface (rear surface) of the substrate 10 of the reflective mask blank 100 shown in Fig. 4.

[0098] <Absorber Film 24> The absorber film 24 of the reflective mask blank 100 of this embodiment is formed on 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 the region (field portion) 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.

[0099] 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.

[0100] 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.

[0101] 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.

[0102] Furthermore, in terms of smoothness and flatness, the crystalline state of the absorber film 24 is preferably an amorphous or microcrystalline structure. If the surface of the absorber film 24 is not smooth and flat, the edge roughness of the absorber pattern 24a increases, which may result in poor 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).

[0103] <Etching mask film 25> Figure 5 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 5 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 of the absorber film 24 to the etching mask film 25 (etching rate of the absorber film 24 / etching rate of the etching mask film 25). The etching selectivity of the absorber film 24 to the etching mask film 25 is preferably 1.5 or more, and more preferably 3 or more.

[0104] The reflective mask blank 100 of this embodiment preferably has an etching mask film 25 on the absorber film 24 .

[0105] 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).

[0106] 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.

[0107] 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.

[0108] 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.

[0109] 6(D), the reflective mask 200 of this embodiment has an absorber pattern 24a obtained by patterning the absorber film 24 of the above-mentioned reflective mask blank 100. The reflective mask 200 shown in FIG. 6(D) has the above-mentioned conductive film 42 on the second main surface (rear surface) of the substrate 10.

[0110] 6(A) to 6(D) are cross-sectional schematic views showing an example of a method for manufacturing a reflective mask 200. The reflective mask blank 100 of this embodiment described above can be used to manufacture the reflective mask 200 of this embodiment. An example of the method for manufacturing the reflective mask 200 will be described below.

[0111] 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. 6(A)). 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. 6(B)).

[0112] 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 absorber patterns 24a are formed (FIG. 6C).

[0113] 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 , S.F. 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.

[0114] After the absorber pattern 24a is formed, the resist pattern 32a is removed with a resist remover solution. 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. 6(D)).

[0115] 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.

[0116] 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.

[0117] 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, making it possible to transfer a finer pattern onto a transfer target in EUV lithography.

[0118] The reflective mask 200 of this embodiment has the above-mentioned conductive film 42 on the second main surface (rear surface) of the substrate 10. Since the reflective mask 200 of this embodiment has the predetermined conductive film 42, it is possible to prevent hydrogen present outside the reflective mask 200 from being incorporated into the conductive film 42 of the reflective mask 200 in an EUV exposure environment. Therefore, the reflective mask 200 of this embodiment can prevent changes in flatness. Furthermore, by using the reflective mask 200 of this embodiment, it is possible to prevent the positional deviation of the pattern of the reflective mask 200 from occurring over time after the reflective mask 200 is fabricated.

[0119] [Method for Manufacturing Semiconductor Device] The method for manufacturing a semiconductor device according to this embodiment includes a step of forming a transfer pattern on a transfer target by performing a lithography process using an exposure apparatus using the above-described reflective mask 200.

[0120] A transfer pattern can be formed on a semiconductor substrate 60 (transfer receiving body) by lithography using the reflective mask 200 of this embodiment. 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.

[0121] According to this embodiment, a semiconductor device can be manufactured using the reflective mask 200 that can suppress the occurrence of pattern misalignment. Therefore, by using the reflective mask 200 of this embodiment, it is possible to increase the density and precision of semiconductor devices.

[0122] A method for transferring a pattern onto a semiconductor substrate 60 with a resist by using EUV light will be described with reference to FIG.

[0123] 7 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.

[0124] 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.

[0125] 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). As a result, a given circuit pattern is transferred onto a 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.

[0126] By using the reflective mask 200 manufactured using the conductive film-formed substrate 40 of this embodiment, it is possible to prevent hydrogen present outside the reflective mask 200 from being incorporated into the conductive film 42 of the reflective mask 200 in an EUV exposure environment. This makes it possible to prevent changes in the flatness of the reflective mask 200. Therefore, by using the reflective mask 200 manufactured using the conductive film-formed substrate 40 of this embodiment, it is possible to manufacture a high-precision semiconductor device.

[0127] 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.

[0128] First, a conductive film 42 was formed on the second 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 and 2 and Comparative Examples 1 and 2.

[0129] <Preparation of Substrate 10> The substrate 10 used to manufacture the conductive film-attached substrate 40 of Examples 1 and 2 and Comparative Examples 1 and 2 was prepared as follows.

[0130] 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. ２ -TiO ２A glass substrate 10 was prepared by polishing the substrate 10 to have a flat and smooth main surface through a rough polishing process, a precision polishing process, a local processing process, and a touch polishing process.

[0131] <Preparation of Conductive Film 42> The conductive film 42 (conductive layer 44 and outermost layer 46) was formed on the second main surface of the substrate 10 of Examples 1 and 2 and Comparative Examples 1 and 2 described above as follows.

[0132] First, the conductive layer 44 of the conductive film 42 of Examples 1 and 2 and Comparative Examples 1 and 2 was formed. The conductive layer 44 was formed by sputtering (or reactive sputtering) in a Xe gas atmosphere with a TaB target facing the rear surface (second main surface) of the substrate 10. The film thickness of the conductive layer 44 was adjusted to the thickness shown in Table 1 by adjusting the film formation time of the conductive layer 44. The composition ratio of the conductive layer 44 analyzed by X-ray photoelectron spectroscopy (XPS) under the measurement conditions described below was Ta:B = 80:20 in all of Examples 1 and 2 and Comparative Examples 1 and 2.

[0133] Next, the outermost layer 46 of the conductive film 42 of Examples 1 and 2 and Comparative Example 2 was formed. The outermost layer 46 was formed by sputtering (or reactive sputtering) with the target shown in Table 2 facing the back surface (second main surface) of the substrate 10. The film thickness of the outermost layer 46 was set to the thickness shown in Table 1 by adjusting the film formation time of the outermost layer 46. The composition ratio (atomic %) of the outermost layer 46 analyzed by X-ray photoelectron spectroscopy (XPS) under the measurement conditions described below was as shown in Table 2.

[0134] In the conductive film 42 of Comparative Example 1, only the conductive layer 44 was formed, and the outermost layer 46 was not formed. However, it is believed that a natural oxide film was formed on the surface of the conductive layer 44 of Comparative Example 1. In this specification, the natural oxide film on the surface of the conductive layer 44 of Comparative Example 1 is considered to be a thin film equivalent to the outermost layer 46.

[0135] In this manner, a substrate 40 with a conductive film having the structure shown in FIG. 1 was produced.

[0136] <Measurement by X-ray Photoelectron Spectroscopy (XPS)> The conductive films 42 of the conductive film-attached substrates 40 of Examples 1 and 2 and Comparative Examples 1 and 2 were analyzed by X-ray photoelectron spectroscopy (XPS). Specifically, the XPS method was used to measure the energies (binding energies) in the range of 180 eV to 205 eV of photoelectrons excited by X-rays irradiated onto the conductive films 42 of the conductive film-attached substrates 40 of Examples 1 and 2 and Comparative Examples 1 and 2 and emitted to the outside, thereby obtaining the photoelectron energy distribution (B1s narrow spectrum).

[0137] In the analysis of the conductive film 42 by X-ray photoelectron spectroscopy (XPS method), two types of analysis were performed: surface analysis and internal analysis. In the surface analysis, X-rays were irradiated from an X-ray source toward the surface of the conductive film 42 of the conductive film-coated substrate 40, and the energy distribution of photoelectrons emitted from the outermost layer 46 of the conductive film 42 was measured. In the internal analysis, the conductive film 42 was excavated by about 10 nm by Ar gas sputtering, and the surface (outermost layer 46) of the conductive film 42 in the excavated region was irradiated with X-rays to measure the energy distribution of photoelectrons emitted from the conductive film 42, thereby analyzing the conductive layer 44 of the conductive film 42. The measurement conditions for the X-ray photoelectron spectroscopy analysis were as follows: X-ray source: AlK α ray (1486.6 eV) Photoelectron detection area: diameter 200 μm Measurement range of photoelectron binding energy: 180 eV to 205 eV Photoelectron detection take-off angle: 45 degrees (detection depth approximately 4 to 5 nm) Step size during measurement: 0.25 eV

[0138] The detection depth by the XPS method is approximately 4 to 5 nm. Therefore, the surface analysis by the XPS method described above can obtain information on the outermost layer 46. Furthermore, the internal analysis by the XPS method described above can obtain information on the conductive film 42.

[0139] Fig. 8 shows B1s narrow spectra of the conductive layer 44 and the outermost layer 46 of the conductive film 42 of the conductive film-coated substrate 40 of Example 1 and Comparative Example 1. The horizontal axis of Fig. 8 represents the photoelectron binding energy (unit: eV), and the vertical axis represents the intensity (signal counts / second). In the B1s narrow spectra, the binding energy of the peak corresponding to the B-O bond is near the dotted line on the left side of Fig. 8 (approximately 193 eV), and the binding energy of the peak corresponding to the B-Ta bond is near the dotted line on the right side of Fig. 8 (approximately 188 eV).

[0140] 8 , the B1s narrow spectrum of the outermost layer 46 of Example 1 has a maximum peak at a binding energy of 190 eV or more and 195 eV or less, and has no peak at a binding energy of 185 eV or more and less than 190 eV. In contrast, the B1s narrow spectrum of the outermost layer 46 of Comparative Example 1 has a maximum peak at a binding energy of 185 eV or more and less than 190 eV. The B1s narrow spectrum of the outermost layer 46 of Comparative Example 1 has a peak at a binding energy of 190 eV or more and 195 eV or less, but the intensity is smaller than the peak at a binding energy of 185 eV or more and less than 190 eV.

[0141] 8 , the B1s narrow spectra of the conductive layers 44 of Example 1 and Comparative Example 1 have maximum peaks at binding energies of 185 eV or more and less than 190 eV. Similar XPS analysis was also performed on the conductive layers 44 and outermost layers 46 of Example 2 and Comparative Example 2. Table 1 shows the peaks in the B1s narrow spectra of the conductive films 42 and outermost layers 46 of the conductive-film-coated substrates 40 of Examples 1 and 2, and Comparative Examples 1 and 2.

[0142] <Hydrogen Content of Conductive Layer 44> The substrates 40 with conductive film of the examples and comparative examples were subjected to a hydrogen exposure process simulating the environment of an exposure machine, and the hydrogen content in the conductive layer 44 after the process was measured using secondary ion mass spectrometry (SIMS). As with the internal analysis using the XPS method described above, the conductive film 42 was dug to a depth of about 10 nm by Ar gas sputtering, and the hydrogen content of the conductive film 42 (conductive layer 44) in the dug region was measured using SIMS. The measurement results of the hydrogen content are shown in the column "Hydrogen Content (Atomic %) of Conductive Layer" in Table 1. A lower hydrogen content in the conductive layer 44 means a higher effect of the outermost layer 46 in suppressing hydrogen from being incorporated into the conductive film 42.

[0143] As shown in Table 1, the hydrogen content of the conductive layer 44 in Examples 1 and 2 was lower than the hydrogen content of the conductive layer 44 in Comparative Examples 1 and 2. Therefore, it can be said that the outermost layer 46 in Examples 1 and 2 is highly effective in suppressing hydrogen from being absorbed into the conductive film 42.

[0144] <Sheet Resistance of Conductive Film 42> The sheet resistance of the conductive film 42 (conductive layer 44 and outermost layer 46) of the conductive-film-coated substrate 40 in the examples and comparative examples was measured by a four-terminal measurement method, with electrodes in contact with the surface of the outermost layer 46. Table 1 shows the measurement results of the sheet resistance.

[0145] <Preparation of multilayer reflective film coated substrate 20> Next, the multilayer reflective film coated substrates 20 of Examples 1 and 2 and Comparative Examples 1 and 2 were prepared. The substrate 10 used was the same as the substrate 10 used in the production of the conductive film coated substrates 40 of Examples 1 and 2 and Comparative Examples 1 and 2. A multilayer reflective film 21 was formed on a first main surface of the substrate 10.

[0146] The multilayer reflective film 21 of the multilayer reflective film coated substrate 20 of the Examples and Comparative Examples was formed as follows: That is, using a Mo target and a Si target, Mo layers (low refractive index layers, thickness 2.8 nm) and Si layers (high refractive index layers, thickness 4.2 nm) were alternately laminated (40 laminated pairs) by ion beam sputtering to form the multilayer reflective film 21 on the above-mentioned substrate 10.

[0147] 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.

[0148] Next, the same conductive film 42 as in the conductive film-coated substrate 40 of Examples 1 and 2 and Comparative Examples 1 and 2 described above was formed on the back surface of the multilayer reflective film-coated substrate 20 on which the multilayer reflective film 21 was not formed.

[0149] In this manner, the multilayer reflective film coated substrates 20 of Examples 1 and 2 and Comparative Examples 1 and 2 were manufactured.

[0150] <Fabrication of reflective mask blank 100> A TaBN film having a thickness of 55 nm was formed by magnetron sputtering (reactive sputtering) on ​​the protective film 22 of the multilayer reflective film coated substrate 20 of the above-described Examples and Comparative Examples as the absorber film 24. The composition of the absorber film 24 was Ta:B:N = 75:12:13 (atomic ratio), and the film thickness was 55 nm.

[0151] In this manner, the reflective mask blanks 100 of the examples and comparative examples were manufactured.

[0152] <Reflection Mask 200> Next, the reflective masks 200 of the example and the comparative example were manufactured using the reflective mask blanks 100 of the example and the comparative example. The manufacture of the reflective mask 200 will be described with reference to FIG.

[0153] First, as shown in Fig. 6(A), 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 this resist film 32, and then developed and rinsed to form a predetermined resist pattern 32a (Fig. 6(B)). Next, using the resist pattern 32a as a mask, the absorber film 24 (TaBN film) was etched with Cl. ２ Dry etching was performed using gas to form an absorber pattern 24a (FIG. 6C), after which the resist pattern 32a was removed (FIG. 6D).

[0154] Finally, wet cleaning was performed using deionized water (DIW), and the reflective masks 200 of Examples 1 and 2 and Comparative Examples 1 and 2 were manufactured.

[0155] <Manufacturing of semiconductor device> The reflective masks 200 of Examples 1 and 2 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 a transfer object. Then, by developing this exposed resist film, a resist pattern was formed on the semiconductor substrate 60 on which the processing film was formed.

[0156] In the reflective masks 200 of Examples 1 and 2, the conductive film 42 includes a predetermined outermost layer 46, which is thought to suppress diffusion of hydrogen into the conductive layer 44. Therefore, by using the reflective masks 200 of Examples 1 and 2, a fine and highly accurate transfer pattern (resist pattern) could be formed on the semiconductor substrate 60 (transfer substrate). On the other hand, the outermost layer 46 of the conductive film 42 of the reflective masks 200 of Comparative Examples 1 and 2 is not the predetermined outermost layer 46. Therefore, in the case of the reflective masks 200 of Comparative Examples 1 and 2, the diffusion of hydrogen into the conductive layer 44 was not suppressed, and a problem occurred in which flatness could not be maintained. Therefore, when the reflective masks 200 of Comparative Examples 1 and 2 were used, a fine and highly accurate transfer pattern (resist pattern) could not be formed on the semiconductor substrate 60 (transfer substrate) compared to Examples 1 and 2.

[0157] When a semiconductor device was manufactured using the reflective mask 200 of Examples 1 and 2, a 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 enabling a semiconductor device having the desired characteristics to be manufactured with a high yield.

[0158]

[0159]

[0160] 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 Conductive layer 46 Outermost 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 with a conductive film comprising: a substrate having two main surfaces; and a conductive film disposed on one of the main surfaces of the substrate, wherein the conductive film comprises an outermost layer disposed on the outermost surface of the conductive film opposite the substrate, and a conductive layer disposed between the outermost layer and the substrate, wherein the outermost layer contains metal (M), boron (B), and oxygen (O), and wherein a narrow B1s spectrum obtained by X-ray photoelectron spectroscopy analysis of the outermost layer has a maximum peak at a binding energy of 190 eV or more and 195 eV or less.

2. The substrate with a conductive film according to claim 1, wherein the detection depth of the outermost layer by X-ray photoelectron spectroscopy is about 4 to 5 nm.

3. The substrate with a conductive film according to claim 1 or 2, wherein the outermost layer has no peak at a binding energy of 185 eV or more and less than 190 eV in the narrow B1s spectrum obtained by analyzing the outermost layer using X-ray photoelectron spectroscopy.

4. The substrate with a conductive film according to claim 1 or 2, wherein the boron (B) content in the outermost layer is 0.5 to 25 atomic %.

5. The substrate with a conductive film according to claim 1 or 2, wherein the conductive layer contains the metal (M) and boron (B).

6. The substrate with a conductive film according to claim 1 or 2, wherein the narrow B1s spectrum obtained by analyzing the conductive layer using X-ray photoelectron spectroscopy has a maximum peak at a binding energy of 185 eV or more but less than 190 eV.

7. The substrate with a conductive film according to claim 1 or 2, wherein the metal (M) is at least one selected from Ta, Cr, Pt, Au, Rh, Ru, Ir and Hf.

8. A reflective mask blank comprising: a substrate having two main surfaces; a conductive film disposed on one of the main surfaces of the substrate; a multilayer reflective film disposed on the other main surface of the substrate; and an absorber film disposed on the multilayer reflective film, wherein the conductive film comprises an outermost layer disposed on the outermost surface of the conductive film opposite the substrate, and a conductive layer disposed between the outermost layer and the substrate, the outermost layer comprising metal (M), boron (B) and oxygen (O), and wherein the outermost layer has a maximum peak at a binding energy of 190 eV or more and 195 eV or less in a B1s narrow spectrum obtained by X-ray photoelectron spectroscopy analysis.

9. The reflective mask blank according to claim 8, wherein the detection depth of the outermost layer by X-ray photoelectron spectroscopy is about 4 to 5 nm.

10. A reflective mask blank according to claim 8 or 9, characterized in that the outermost layer has no peak at a binding energy of 185 eV or more and less than 190 eV in the narrow B1s spectrum obtained by analysis by X-ray photoelectron spectroscopy.

11. A reflective mask blank according to claim 8 or 9, wherein the boron (B) content in the outermost layer is 0.5 to 25 atomic %.

12. A reflective mask blank according to claim 8 or 9, characterized in that the conductive layer contains the metal (M) and boron (B).

13. A reflective mask blank according to claim 8 or 9, characterized in that the narrow B1s spectrum obtained by analyzing the conductive layer using X-ray photoelectron spectroscopy has a maximum peak at a binding energy of 185 eV or more but less than 190 eV.

14. The reflective mask blank according to claim 8 or 9, wherein the metal (M) is at least one selected from Ta, Cr, Pt, Au, Rh, Ru, Ir, and Hf.

15. A reflective mask comprising: a substrate having two main surfaces; a conductive film disposed on one of the main surfaces of the substrate; a multilayer reflective film disposed on the other main surface of the substrate; and an absorber pattern disposed on the multilayer reflective film, wherein the conductive film comprises an outermost layer disposed on the outermost surface of the conductive film opposite the substrate, and a conductive layer disposed between the outermost layer and the substrate, the outermost layer containing metal (M), boron (B) and oxygen (O), and wherein a narrow B1s spectrum of the outermost layer obtained by X-ray photoelectron spectroscopy analysis has a maximum peak at a binding energy of 190 eV or more and 195 eV or less.

16. The reflective mask according to claim 15, wherein the detection depth of the outermost layer by X-ray photoelectron spectroscopy is about 4 to 5 nm.

17. The reflective mask according to claim 15 or 16, wherein the outermost layer has no peak at a binding energy of 185 eV or more and less than 190 eV in the narrow B1s spectrum obtained by analyzing the outermost layer using X-ray photoelectron spectroscopy.

18. The reflective mask according to claim 15 or 16, wherein the boron (B) content in the outermost layer is 0.5 to 25 atomic %.

19. The reflective mask according to claim 15 or 16, wherein the conductive layer contains the metal (M) and boron (B).

20. The reflective mask according to claim 15 or 16, characterized in that the narrow B1s spectrum obtained by analyzing the conductive layer using X-ray photoelectron spectroscopy has a maximum peak at a binding energy of 185 eV or more but less than 190 eV.

21. The reflective mask according to claim 15 or 16, wherein the metal (M) is at least one selected from the group consisting of Ta, Cr, Pt, Au, Rh, Ru, Ir, and Hf.

22. A method for manufacturing a semiconductor device, comprising the step of using the reflective mask according to claim 15 or 16 to carry out a lithography process using an exposure device to form a transfer pattern on a transfer target.