Reflective mask blank, reflective mask, and method for manufacturing semiconductor device

Abstract

Provided is a reflective mask blank for manufacturing a reflective mask in which an absorber film (absorber pattern) can be prevented from peeling off.　This reflective mask blank is characterized by comprising: a substrate; a multilayer reflection film formed on the substrate; and an absorber film formed on the multilayer reflection film, wherein the absorber film includes a first region in which, in a Ta4f spectrum obtained by analyzing the absorber film by the X ray photoelectron spectroscopy and normalized by the maximum intensity value of a Ta4f peak, a difference D between the minimum intensity value between a Ta4f5 / 2 peak and a Ta4f7 / 2 peak and the interpolated value of intensity in binding 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 0.34 or less.

Description

Reflective mask blank, reflective mask, and method for manufacturing semiconductor device

[0001] The present invention relates to a reflective mask used in the manufacture of semiconductor devices, a method for manufacturing the same, and a reflective mask blank used to manufacture the reflective mask. The present invention also relates to a method for manufacturing a semiconductor device using the reflective mask.

[0002] 2. Description of the Related Art In recent years, with the increasing demand for higher density and higher precision in VLSI devices, EUV lithography, an exposure technique using extreme ultraviolet (hereinafter referred to as EUV) light, has been proposed.

[0003] A reflective mask has a multilayer reflective film formed on a substrate to reflect exposure light, and an absorber pattern, which is a patterned absorber film formed on the multilayer reflective film to absorb the exposure light. In EUV lithography using a reflective mask, the light image reflected by the multilayer reflective film of the reflective mask is transferred onto a semiconductor substrate (transfer target) such as a silicon wafer through a reflective optical system. A reflective mask blank is used to manufacture a reflective mask.

[0004] As an example of a reflective mask blank, Patent Document 1 describes a reflective mask blank having, on a substrate, a multilayer reflective film that reflects EUV light and an absorbing film that absorbs EUV light, in this order. Patent Document 1 further describes that the absorbing film is a tantalum-based material film containing a tantalum-based material, and that in an X-ray diffraction pattern of the absorbing film, the peak diffraction angle 2θ of the peak derived from the tantalum-based material is 36.8 degrees or more, and the half-value width of the peak derived from the tantalum-based material is 1.5 degrees or more.

[0005] As an example of a reflective mask blank, Patent Document 2 describes a reflective mask blank having an absorber film on a multilayer reflective film-coated substrate having a substrate, a multilayer reflective film provided on the substrate, and a protective film provided on the multilayer reflective film. Patent Document 2 also describes that the protective film contains ruthenium (Ru), rhodium (Rh), and at least one additive element selected from titanium (Ti), zirconium (Zr), yttrium (Y), niobium (Nb), vanadium (V), and hafnium (Hf).

[0006] JP 2019-035929 A International Publication No. 2021 / 200325

[0007] The above-mentioned EUV lithography is an exposure technology that uses extreme ultraviolet light (EUV light). EUV light is light in the wavelength band of the soft X-ray region or vacuum ultraviolet region, and specifically light with a wavelength of about 0.2 to 100 nm. In the case of EUV lithography, EUV light with a wavelength of 13 to 14 nm (for example, a wavelength of 13.5 nm) can be used. In this specification, light includes not only visible light but also electromagnetic waves.

[0008] EUV lithography uses a reflective mask with an absorber pattern. EUV light irradiated onto the reflective mask is absorbed in areas where the absorber pattern is present and reflected in areas where the absorber pattern is not present. A multilayer reflective film (including a protective film) is exposed in areas where the absorber pattern is not present. The multilayer reflective film exposed on the surface of the reflective mask reflects the EUV light. In EUV lithography, the optical image reflected by the multilayer reflective film (areas where the absorber pattern is not present) is transferred onto a semiconductor substrate (transfer target) such as a silicon wafer through a reflection optical system.

[0009] The absorber pattern disposed on the multilayer reflective film of the reflective mask is formed by patterning the absorber film of the reflective mask blank. Furthermore, thin films other than the absorber film, such as a protective film and an etching mask film, may be disposed on the multilayer reflective film. Furthermore, the absorber film may be composed of multiple different layers (thin films). Therefore, multiple thin films, including at least the multilayer reflective film and the absorber film, are disposed on the substrate of the reflective mask blank.

[0010] If the adhesion at the interface between adjacent layers in multiple different layers (thin films) stacked on a substrate is insufficient, one layer may peel off from another layer during the manufacturing process of the reflective mask blank and / or the manufacturing process of the reflective mask, resulting in defects.

[0011] Furthermore, when the stress in the absorber film changes, deformation due to the stress tends to cause peeling of the absorber film, the protective film and / or the multilayer reflective film.

[0012] Pattern transfer onto a semiconductor substrate using an exposure apparatus is performed in a hydrogen atmosphere. Therefore, during exposure for pattern transfer, the reflective mask is placed in a hydrogen atmosphere. As a result, hydrogen may penetrate into the absorber film of the reflective mask during exposure and accumulate at grain boundaries, causing stress changes in the absorber film. As a result, film peeling, known as blisters, is likely to occur between films with low adhesion, particularly at the interface between the multilayer reflective film and the protective film on the multilayer reflective film. This may result in film peeling of the absorber film (absorber pattern), protective film, and / or multilayer reflective film of the reflective mask.

[0013] Ta-based absorber films tend to absorb hydrogen, and therefore, when a Ta-based absorber film is used as the material for the absorber film of a reflective mask blank, the adverse effects caused by the penetration of hydrogen into the absorber film described above tend to occur.

[0014] Therefore, an object of the present invention is to provide a reflective mask that can suppress peeling of the absorber film (absorber pattern), protective film, and / or multilayer reflective film.

[0015] Another object of the present invention is to provide a reflective mask blank for manufacturing a reflective mask capable of suppressing peeling of an absorber film (absorber pattern), a protective film, and / or a multilayer reflective film, and to provide a method for manufacturing a semiconductor device using the reflective mask.

[0016] In order to solve the above problems, the present invention has the following configuration.

[0017] (Configuration 1) Configuration 1 includes a substrate, a multilayer reflective film formed on the substrate, and an absorber film formed on the multilayer reflective film, wherein the absorber film contains Ta4f in a spectrum of Ta4f normalized by the maximum intensity value of the Ta4f peak obtained by analyzing the absorber 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 reflective mask blank 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 0.34 or less.

[0018] (Configuration 2) Configuration 2 is the reflective mask blank of configuration 1, wherein the first region contains tantalum and nitrogen.

[0019] (Configuration 3) Configuration 3 is the reflective mask blank according to configuration 1 or 2, wherein the first region contains 12 atomic % or more of nitrogen.

[0020] (Structure 4) Structure 4 is the reflective mask blank according to any one of Structures 1 to 3, further comprising a protective film between the multilayer reflective film and the absorber film, the protective film including a lower layer and an upper layer formed on the lower layer.

[0021] (Configuration 5) Configuration 5 is the reflective mask blank of configuration 4, wherein the upper layer of the protective film contains ruthenium.

[0022] (Configuration 6) Configuration 6 is the reflective mask blank according to any one of configurations 1 to 5, further comprising an etching mask film including two or more layers on the absorber film.

[0023] (Configuration 7) Configuration 7 is the reflective mask blank according to configuration 6, wherein the etching mask film contains ruthenium.

[0024] (Configuration 8) Configuration 8 is the reflective mask blank according to configuration 6 or 7, wherein the etching mask film contains tantalum.

[0025] (Configuration 9) Configuration 9 includes a substrate, a multilayer reflective film formed on the substrate, and an absorber pattern formed on the multilayer reflective film, wherein the absorber pattern has a Ta4f peak intensity normalized by the maximum intensity value of the Ta4f peak, the Ta4f peak intensity being obtained by analyzing the absorber pattern 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 reflective mask is characterized by including a first region in which the difference D between the interpolated value of the intensity at the minimum binding energy on a linear interpolation function obtained by linear interpolation based on the peaks is 0.34 or less.

[0026] (Configuration 10) Configuration 10 is the reflective mask of configuration 9, wherein the first region contains tantalum and nitrogen.

[0027] (Configuration 11) Configuration 11 is the reflective mask of configuration 9 or 10, wherein the first region contains 12 atomic % or more of nitrogen.

[0028] (Configuration 12) Configuration 12 is the reflective mask of any one of Configurations 9 to 11, further comprising a protective film between the multilayer reflective film and the absorber film, the protective film including a lower layer and an upper layer formed on the lower layer.

[0029] (Configuration 13) Configuration 13 is the reflective mask of configuration 12, wherein the upper layer of the protective film contains ruthenium.

[0030] (Configuration 14) Configuration 14 is a method for manufacturing a semiconductor device, characterized in that the absorber pattern of the reflective mask of any one of configurations 9 to 13 is transferred onto a transfer target on a semiconductor substrate.

[0031] According to the present invention, it is possible to provide a reflective mask that can suppress peeling of the absorber film (absorber pattern), protective film, and / or multilayer reflective film.

[0032] Furthermore, the present invention can provide a reflective mask blank for manufacturing a reflective mask capable of suppressing film peeling of an absorber film (absorber pattern), a protective film, and / or a multilayer reflective film. Furthermore, the present invention can provide a method for manufacturing a semiconductor device using the reflective mask.

[0033] Fig. 1 is a cross-sectional view schematically showing an example of a reflective mask blank of the present embodiment. Fig. 2 is a cross-sectional view schematically showing another example of the reflective mask blank of the present embodiment. Fig. 3 is a cross-sectional view schematically showing yet another example of the reflective mask blank of the present embodiment. Fig. 4 is a cross-sectional view schematically showing an example of a method for manufacturing a reflective mask of the present embodiment. Fig. 5 is a schematic view showing an example of an EUV exposure apparatus. Fig. 6 is a view showing an example of a spectrum of a Ta4f peak obtained by analyzing an absorber film of the reflective mask blank of the present embodiment by X-ray photoelectron spectroscopy (XPS).

[0034] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that the following embodiments are intended to specifically explain the present invention, and are not intended to limit the scope of the present invention.

[0035] Fig. 1 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. 1 has a multilayer reflective film 2, a protective film 3, and an absorber film 4 on one main surface of a substrate 1. The reflective mask blank 100 shown in Fig. 1 can also have a back surface conductive film 5 on the other main surface (back surface) of the substrate 1.

[0036] Fig. 2 is a cross-sectional schematic view showing another example of the reflective mask blank 100 of the present embodiment. The reflective mask blank 100 shown in Fig. 2 has an etching mask film 6 on an absorber film 4. The reflective mask blank 100 of the present embodiment can also have a back surface conductive film 5 on the back surface of the substrate 1.

[0037] 3 is a schematic cross-sectional view of a reflective mask blank 100 in which the absorber film 4 is made up of two layers, an absorber film lower layer 42 and an absorber film upper layer 44. As shown in FIG. 3, the absorber film 4 can have a multi-layer laminated structure.

[0038] In this specification, "thin film B is disposed (formed) on thin film A (or substrate 1)" not only means that thin film B is disposed (formed) in contact with the surface of thin film A (or substrate 1), but also means that another thin film C is present between thin film A (or substrate 1) 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 1)" means that thin film A (or substrate 1) 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 1, etc.

[0039] The reflective mask blank 100 and the reflective mask 200 of this embodiment will be specifically described below.

[0040] <Reflective mask blank 100> The reflective mask blank 100 of this embodiment comprises a substrate 1, a multilayer reflective film 2 formed on the substrate 1, and an absorber film 4 formed on the multilayer reflective film 2. The reflective mask blank 100 of this embodiment may further comprise a protective film 3 between the multilayer reflective film 2 and the absorber film 4. Furthermore, the reflective mask blank 100 of this embodiment may further comprise a back surface conductive film 5 on the back surface of the substrate 1 (the main surface opposite to the main surface on which the multilayer reflective film 2 is formed). The configuration of the reflective mask blank 100 of this embodiment will now be described in detail.

[0041] <<Substrate 1>> The substrate 1 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.

[0042] The main surface (first main surface) of the substrate 1 on which a transfer pattern (the absorber pattern 4a described below) is formed is preferably processed to increase its flatness. Increasing the flatness of the main surface of the substrate 1 can improve the positional accuracy and transfer accuracy of the pattern. For example, in the case of EUV exposure, in a 132 mm × 132 mm area of ​​the main surface of the substrate 1 on which the transfer pattern is formed, the flatness is preferably 0.1 μm or less, more preferably 0.05 μm or less, and particularly preferably 0.03 μm or less. Furthermore, the main surface (back 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 back 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 amount) 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 substrate 1 above the focal plane, which is determined by the least squares method using the surface of substrate 1 as a reference, and the lowest point on the surface of substrate 1 below this focal plane.

[0043] In the case of EUV exposure, the surface roughness of the main surface of the substrate 1 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.

[0044] The substrate 1 preferably has high rigidity to prevent deformation due to film stress of the thin films (such as the multilayer reflective film 2) formed thereon. In particular, it is preferable that the substrate 1 has a high Young's modulus of 65 GPa or more.

[0045] <<Multilayer reflective film 2>>

[0046] The reflective mask blank 100 of the embodiment includes a multilayer reflective film 2. The multilayer reflective film 2 provides the reflective mask 200 with the function of reflecting EUV light. The multilayer reflective film 2 is a multilayer film in which layers each containing materials with different refractive indices as main components are periodically stacked.

[0047] Generally, the multilayer reflective film 2 is a multilayer film in which thin films of high refractive index materials, i.e., light elements or compounds thereof (high refractive index layers), and thin films of low refractive index materials, i.e., heavy elements or compounds thereof (low refractive index layers), are alternately stacked in approximately 30 to 60 cycles.

[0048] The multilayer film used as the multilayer reflective film 2 can have a structure in which multiple periods of a high-refractive-index layer / low-refractive-index layer stacked in this order on the substrate 1 are stacked. Alternatively, the multilayer film can have a structure in which multiple periods of a low-refractive-index layer / high-refractive-index layer stacked in this order on the substrate 1 are stacked. It is preferable that the outermost layer of the multilayer reflective film 2, i.e., the surface layer of the multilayer reflective film 2 farthest from the substrate 1, is a high-refractive-index layer. In the above-described multilayer film, when multiple periods of a high-refractive-index layer / low-refractive-index layer stacked in this order on the substrate 1 are stacked, the uppermost layer is the low-refractive-index layer. In this case, if the low-refractive-index layer constitutes the outermost surface of the multilayer reflective film 2, it is easily oxidized, which may reduce the reflectivity of the reflective mask 200. Therefore, it is preferable to form the multilayer reflective film 2 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 on the substrate 1, and multiple cycles are stacked, the uppermost layer is the high-refractive index layer, and therefore, in this case, there is no need to form an additional high-refractive index layer.

[0049] The high-refractive index layer can be a layer containing silicon (Si). Examples of materials containing Si include elemental Si and Si compounds containing 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 EUV light reflectivity 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 be doped with boron (B), carbon (C), nitrogen (N), oxygen (O), and / or hydrogen (H). In the reflective mask blank 100 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, as a multilayer reflective film 2 for reflecting EUV light with a wavelength of 13 nm to 14 nm (e.g., a wavelength of 13.5 nm), 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. Furthermore, in the reflective mask blank 100 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, as a multilayer reflective film 2 for reflecting EUV light with a wavelength of 13 nm to 14 nm (e.g., a wavelength of 13.5 nm), 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.

[0050] The reflectivity of the multilayer reflective coating 2 can be 65% or more, and the upper limit can be 73%. The reflectivity in this specification refers to the value when the angle of incidence of EUV light with respect to the multilayer reflective coating 2 (including the protective coating 3) is the same as the angle of incidence of EUV light with respect to the target to be irradiated, which is used in exposure when a pattern is transferred using the reflective mask 200 or a reflective mask 200 manufactured from the reflective mask blank 100. When transferring a pattern, EUV light from the EUV light source is irradiated onto the reflective mask 200 via an illumination optical system at an angle tilted, for example, by 6 to 8 degrees, with respect to a plane perpendicular to the main surface of the reflective mask 200. The angle of incidence of EUV light with respect to the multilayer reflective coating 2 is not particularly limited, but can be, for example, 6 degrees.

[0051] The thickness and period of each constituent layer of the multilayer reflective film 2 can be appropriately selected depending on the exposure wavelength. Specifically, the thickness and period of each constituent layer of the multilayer reflective film 2 can be selected so as to satisfy the law of Bragg reflection. The multilayer reflective film 2 includes a plurality of high refractive index layers and a plurality of low refractive index layers, but the thicknesses of the high refractive index layers and the low refractive index layers do not necessarily have to be the same.

[0052] The multilayer reflective film 2 may be any known film in the art. The multilayer reflective film 2 can be formed by depositing each layer by, for example, ion beam sputtering. In the case of the Mo / Si periodic multilayer film described above, for example, an Si film having a thickness of about 4 nm is first deposited on the substrate 1 by ion beam sputtering or magnetron sputtering using a Si target, and then an Mo film having a thickness of about 3 nm is deposited using a Mo target. This constitutes one period, and 30 to 60 periods are stacked to form the multilayer reflective film 2 (the outermost layer is a Si film). Note that, although 60 periods require more steps than 30 periods, the reflectivity for EUV light can be increased.

[0053] Furthermore, in the reflective mask blank 100 of this embodiment, an underlayer may be formed between the substrate 1 and the multilayer reflective film 2. The underlayer can be formed for the purposes of improving the smoothness of the main surface of the substrate 1, reducing defects, enhancing the reflectivity of the multilayer reflective film 2, and correcting stress in the multilayer reflective film 2.

[0054] <<Protective film 3>> The reflective mask blank 100 of this embodiment preferably includes a protective film 3 between the multilayer reflective film 2 and the absorber film 4, which will be described later. The protective film 3 is arranged in contact with the surface of the multilayer reflective film 2 that is farthest from the first main surface of the substrate 1. When the reflective mask blank 100 includes the protective film 3, the reflected light of the multilayer reflective film 2 means light that has entered the multilayer reflective film 2 via the protective film 3 and is reflected via the protective film 3. That is, when the reflective mask blank 100 includes the protective film 3, the reflected light from the surface of the protective film 3 in a state in which the protective film 3 is formed on the multilayer reflective film 2 on the substrate 1 may be measured as the reflected light of the multilayer reflective film 2.

[0055] In the reflective mask blank 100 of this embodiment, the protective film 3 is formed between the multilayer reflective film 2 and the absorber film 4, thereby making it possible to suppress damage to the surface of the multilayer reflective film 2 when manufacturing a reflective mask 200 (EUV mask) using the reflective mask blank 100. As a result, the resulting reflective mask 200 has good reflectance characteristics for EUV light.

[0056] The protective film 3 preferably contains at least one selected from ruthenium (Ru), rhodium (Rh), and iridium (Ir). The protective film 3 more preferably contains at least one selected from ruthenium (Ru) and rhodium (Rh). The protective film 3 may further contain an additive element in addition to the above elements. The additive element contained in the protective film 3 is preferably one or more elements selected from Tl, Hf, Ti, Zr, Mn, In, Ga, Cd, Bi, Ta, Pb, Ag, Al, V, Nb, Sn, Zn, Hg, Cr, Fe, Sb, W, Mo, and Cu.

[0057] The Ru content of the protective film 3 is 50 atomic % or more and less than 100 atomic %, preferably 80 atomic % or more and less than 100 atomic %, and more preferably 95 atomic % or more and less than 100 atomic %. The Rh content is 10 atomic % or more and less than 70 atomic %, preferably 20 atomic % or more and less than 60 atomic %, and more preferably 30 atomic % or more and less than 50 atomic %. In this case, the protective film 3 can be provided with sufficient reflectivity for EUV light, mask cleaning resistance, an etching stopper function when the absorber film 4 is etched, and a function of preventing deterioration of the multilayer reflective film 2 over time.

[0058] Furthermore, the protective film 3 can have a laminated structure of two or more layers. The protective film 3 of the reflective mask blank 100 of this embodiment preferably has a protective film 3 including a lower layer and an upper layer formed on the lower layer between the multilayer reflective film 2 and the absorber film 4. The adhesion between the multilayer reflective film 2 and the absorber film 4 may be weak. By including an appropriate lower layer between the upper layer that functions as the protective film 3 and the multilayer reflective film 2, the adhesion between the protective film 3 and the multilayer reflective film 2 can be increased. As the material for the lower layer, a material that can increase adhesion to the multilayer reflective film 2 can be selected.

[0059] In the reflective mask blank 100 of this embodiment, when the protective film 3 has a lower layer and an upper layer, the upper layer of the protective film 3 preferably contains ruthenium (Ru). The lower layer of the protective film 3 may also contain ruthenium (Ru). The lower layer and the upper layer may contain nitrogen (N), oxygen (O), carbon (C), boron (B) and / or hydrogen (H). When the upper layer contains ruthenium (Ru), the protective film 3 functions to protect the multilayer reflective film 2 and can also improve the adhesion of the protective film 3 to the multilayer reflective film 2.

[0060] Furthermore, when the protective film 3 has a lower layer and an upper layer, it is preferable that the lower layer of the protective film 3 contains a first metal different from ruthenium (Ru), and the upper layer contains a second metal different from both ruthenium (Ru) and the first metal. The first metal can be selected from, for example, molybdenum (Mo), niobium (Nb), zirconium (Zr), yttrium (Y), boron (B), titanium (Ti), and lanthanum (La). Niobium (Nb) is preferably used as the first metal. The second metal can be selected from, for example, aluminum (Al), yttrium (Y), zirconium (Zr), niobium (Nb), chromium (Cr), rhodium (Rh), and hafnium (Hf). Niobium (Nb), chromium (Cr), or rhodium (Rh) is preferably used as the second metal, and alloys thereof may also be used. The upper layer preferably contains Ru and Rh, and in this case, it is preferable that it further contains nitrogen (N), niobium (Nb) and / or chromium (Cr). Alternatively, the lower layer of the protective film 3 may contain ruthenium (Ru), and the upper layer may contain a second metal. The protective film 3 having the above-described configuration functions to protect the multilayer reflective film 2, and can further increase the adhesion of the protective film 3 to the multilayer reflective film 2 and the adhesion of the protective film 3 to the absorber film 4.

[0061] <<Backside Conductive Film 5>> The reflective mask blank 100 of this embodiment can have a backside conductive film 5 for electrostatic chucks. The backside conductive film 5 can be formed on the second main surface (backside) of the substrate 1. The second main surface is the main surface opposite to the surface (first main surface) on which the multilayer reflective film 2 is formed. If an intermediate layer such as a hydrogen penetration suppression film is formed on the second main surface of the substrate 1, the backside conductive film 5 can be formed on the intermediate layer. For electrostatic chucks, the sheet resistance required for the backside conductive film 5 is typically 100 Ω / □ (Ω / square) or less. The backside conductive film 5 can be formed by, for example, magnetron sputtering or ion beam sputtering using a target made of a metal such as chromium or tantalum, or an alloy thereof. The chromium (Cr)-containing material of the backside conductive film 5 is preferably a Cr compound containing Cr and at least one element selected from boron, nitrogen, oxygen, carbon, and hydrogen. Examples of Cr compounds include CrN, CrON, CrCN, CrCON, CrBN, CrBON, CrBCN, and CrBOCN. The tantalum (Ta)-containing material of the backside conductive film 5 is preferably Ta (tantalum), a Ta-containing alloy, or a Ta compound containing at least one of boron, nitrogen, oxygen, carbon, and hydrogen. Examples of Ta compounds include TaB, TaN, TaO, TaON, TaCON, TaBN, TaBO, TaBON, TaBCON, TaHf, TaHfO, TaHfN, TaHfON, TaHfCON, TaSi, TaSiO, TaSiN, TaSiON, and TaSiCON. The thickness of the back surface conductive film 5 is not particularly limited as long as it satisfies the function of the electrostatic chuck, but is usually 10 nm to 200 nm. The back surface conductive film 5 also serves to adjust the stress on the second main surface side of the mask blank 100. That is, the back surface conductive film 5 is adjusted to achieve a balance with the stress from the various films formed on the first main surface side, so as to obtain a flat reflective mask blank 100.

[0062] It should be noted that the reflective mask blank 100 does not necessarily need to include the back surface conductive film 5. For example, the back surface conductive film 5 can be formed, if necessary, on the reflective mask blank 100 on which the absorber film 4 described below has been formed.

[0063] 1 and 2 , the absorber film 4 of the reflective mask blank 100 of this embodiment is disposed on the above-mentioned multilayer reflective film 2. When the reflective mask blank 100 includes a protective film 3, the absorber film 4 is disposed on the protective film 3. The absorber film 4 can be disposed in contact with the surface of the protective film 3. When the reflective mask blank 100 does not include a protective film 3, the absorber film 4 can be disposed in contact with the surface of the multilayer reflective film 2.

[0064] The basic function of the absorber film 4 is to absorb EUV light. The reflectance of the absorber film 4 for EUV light is selected, for example, between 0.1% and 40%. The absorber film 4 may be an absorber film 4 designed to absorb EUV light, or an absorber film 4 with a phase shift function that takes into account the phase difference of EUV light. An absorber film 4 designed to absorb EUV light can be called a binary film. A binary film has a reflectance of less than 3%, preferably less than 2.5%, for EUV light. When the absorber film 4 contains 50 atomic % or more of tantalum (Ta), it can be preferably used as a binary film. An absorber film 4 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 4 with a phase shift function, the portion where the absorber film 4 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 4 is not formed, the EUV light is reflected from the multilayer reflective coating 2 (via the protective coating 3, if present). This results in a desired phase difference between the light reflected from the absorber film 4 having a phase shift function and the light reflected from the field portion. The absorber film 4 having a phase shift function is formed so that the phase difference between the light reflected from the absorber film 4 and the light reflected from the multilayer reflective coating 2 is 100 to 310 degrees. The phase difference is preferably 150 degrees or more, more preferably 180 degrees or more, and even more preferably 200 degrees or more. The phase difference is preferably 300 degrees or less, more preferably 280 degrees or less, and even more preferably 250 degrees or less. Light beams having opposite phase differences interfere with each other at the pattern edge, thereby improving the image contrast of the projected optical image. This improvement in image contrast increases resolution and can increase various exposure latitudes, such as exposure dose latitude and focus latitude. When the absorber film 4 has a phase shift function, it preferably has a reflectance of 3% or more and 40% or less for EUV light.

[0065] The absorber film 4 of the reflective mask blank 100 of this embodiment (sometimes referred to as the "absorber film 4 of this embodiment") includes a predetermined first region. The first region of the absorber film 4 is a region where a predetermined difference D is 0.34 or less in the Ta4f peak obtained by analyzing the absorber film 4 by X-ray photoelectron spectroscopy (XPS). Figure 6 shows the Ta4f peak obtained by analyzing the absorber film 4 by X-ray photoelectron spectroscopy (XPS). ５／２ Peak and Ta4f ７／２ 1 shows an example of a Ta4f peak consisting of two peaks.

[0066] In this specification, the term "first region" can refer to a region within a predetermined range in the film thickness direction of the absorber film 4. The first region can be located, for example, in an internal region of the absorber film 4 excluding a surface region and a lower interface region located within a range from the two main surfaces of the absorber film 4 to a predetermined depth. Here, the surface region extends from the outermost surface of the absorber film 4 toward the first main surface of the substrate 1, for example, within a range of 5 nm in film thickness. The outermost surface of the absorber film 4 is the surface of the absorber film 4 farthest from the first main surface of the substrate 1. The lower interface region extends from the interface between the absorber film 4 and the film directly below the absorber film 4 (the multilayer reflective film 2 or the protective film 3) toward the outermost surface of the absorber film 4, for example, within a range of 5 nm in film thickness. For example, the first region can be an internal region of the absorber film 4 excluding a range of 5 nm from the surface of the absorber film 4, in which the predetermined difference D is 0.34 or less.

[0067] When the absorber film 4 includes multiple layers, the internal region excludes not only the lower interface region and the surface region, but also the layer interface region within 5 nm of the interface between adjacent layers. When the layer to be analyzed among the multiple layers included in the absorber film 4 has a very small thickness (10 nm or less), the predetermined depth range can be a region including at least the central position of the layer to be analyzed in the thickness direction. The internal region of the layer to be analyzed with a small thickness may be a region within 25% of the total thickness of the layer to be analyzed, both above and below the central position of the layer to be analyzed in the thickness direction.

[0068] The first region of the absorber film 4 may be located in the surface region, the lower interface region, and / or the layer interface region. The film thickness of the surface region, the lower interface region, and / or the layer interface region is very small. Therefore, the presence or absence of the first region can be determined from the value of the difference D at the center position in the film thickness direction of each of the surface region, the lower interface region, and / or the layer interface region.

[0069] 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.

[0070] When the absorber film 4 of this embodiment is measured by X-ray photoelectron spectroscopy (XPS), the Ta4f peak of photoelectrons caused by electrons in the Ta4f orbital is observed in the binding energy range of approximately 20 eV to 30 eV.

[0071] In analyzing the absorber film 4 using X-ray photoelectron spectroscopy (XPS), X-rays are irradiated from an X-ray source toward the absorber film 4 of the reflective mask blank 100, and the energy distribution of photoelectrons emitted from the absorber film 4 can be measured. When performing X-ray photoelectron spectroscopy (XPS) on the absorber film 4, the absorber film 4 can be excavated by Ar gas sputtering, for example, by approximately 1 nm per measurement, and the surface of the excavated region of the absorber film 4 can be measured by XPS. By repeating the excavation of the absorber film 4 by Ar gas sputtering and the measurement by XPS throughout the entire depth direction of the absorber film 4, XPS measurement results can be obtained for the absorber film 4 in the depth direction. The internal region can then be identified from the measurement results. The number of integration times in the XPS analysis is preferably 8 or more. This allows for more reliable results to be obtained.

[0072] The X-ray irradiation area can be any area in the in-plane direction of the absorber film 4. In top view, the center of the irradiation area preferably coincides with the center of the outermost surface of the absorber film 4. The center of the X-ray irradiation area is the center of the circle if the irradiation area is circular, and the intersection of the diagonals of the rectangle if the irradiation area is rectangular. The same applies to the center of the outermost surface of the absorber film 4. Note that the X-ray irradiation area is usually circular. In top view, the center of the outermost surface of the absorber film 4 preferably coincides with the center (intersection of the diagonals) of the first main surface of the substrate 1. For example, the X-ray irradiation area can be a circular area with a diameter of 200 μm whose center coincides with the center of the outermost surface of the absorber film 4.

[0073] 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

[0074] 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 absorber film 4 is dug by approximately 1 nm per measurement by Ar gas sputtering, it is possible to measure photoelectrons emitted from a predetermined depth in the depth direction of the absorber film 4.

[0075] When analyzing the absorber film 4 of this embodiment using X-ray photoelectron spectroscopy (XPS), the absorber film 4 is repeatedly excavated by Ar gas sputtering to a depth of about 1 nm per measurement. Then, as described above, the Ta4f spectrum is analyzed at any depth position within the identified internal region. This makes it possible to determine whether the absorber film 4 has a first region in which the predetermined difference D is 0.34 or less.

[0076] As described above, the first region can be a region of a predetermined range in the thickness direction of the absorber film 4 (for example, an internal region of the absorber film 4 excluding a range of 5 nm from the surface of the absorber film 4). When determining whether the absorber film 4 has the first region, it can be determined that the absorber film 4 has the first region when, as a result of measurement and analysis using a predetermined XPS method, a predetermined difference D is 0.34 or less at at least one location at any depth in the depth direction of the absorber film 4. It can also be determined that the absorber film 4 has the first region when the predetermined difference D is 0.34 or less in a range of 5 nm or more in the depth direction at any depth greater than 5 nm (internal region) of the absorber film 4. The first region can be an internal region of the absorber film 4 excluding a range of 5 nm from the surface of the absorber film 4, where the predetermined difference D is 0.34 or less. The film thickness of the first region is preferably 40% or more of the total film thickness of the absorber film 4, more preferably 50% or more, and even more preferably 60% or more. The film thickness of the first region can be 100% of the total film thickness of the absorber film 4. When the absorber film 4 includes multiple layers, it is sufficient that at least one of the multiple layers satisfies the above condition. More preferably, the layer with the largest film thickness among the multiple layers of the absorber film 4 satisfies the above condition. Even more preferably, all of the multiple layers of the absorber film 4 satisfy the above condition. When the absorber film 4 includes a buffer layer as the bottom layer, the buffer layer does not necessarily have to have the first region.

[0077] The predetermined difference D may be constant in the depth (film thickness) direction of the absorber film 4, or may vary in the depth direction. When the difference D varies in the depth direction, it is sufficient for the absorber film 4 to have at least one region where the predetermined difference D is 0.34 or less. However, it is particularly preferable that the predetermined difference D be smallest in the region farthest from the first main surface of the substrate in the tantalum-containing layer of the absorber film 4. Even when the absorber film 4 includes multiple layers, it is sufficient for the absorber film 4 to have at least one layer where the predetermined difference D is 0.34 or less. However, it is particularly preferable that the difference D of the tantalum-containing layer farthest from the first main surface of the substrate be smaller than the difference D of the other tantalum-containing layers. Even when the predetermined difference D varies in the depth direction as described above, film peeling in the absorber film 4, the protective film 3, and / or the multilayer reflective coating 2 can be more efficiently suppressed by having the difference D be smallest in the region farthest from the first main surface of the substrate in the tantalum-containing layer, or in the tantalum-containing layer farthest from the first main surface of the substrate.

[0078] FIG. 6 shows the Ta4f ５／２ Peak and Ta4f ７／２ An example of a Ta4f peak consisting of two peaks is shown in Fig. 1. The predetermined difference D in the Ta4f peak of the absorber film 4 of this embodiment can be determined as follows.

[0079] First, the absorber film 4 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 "binding energy of Ta4f") of photoelectrons due to the Ta4f orbital. The range of binding energy measurement by X-ray photoelectron spectroscopy can be, for example, from 15 eV to 35 eV.

[0080] 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.

[0081] The peak of the Ta4f spectrum (Ta4f peak) is Ta4f５／２ 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 E ｍｉｎ 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 absorber film 4 of this embodiment includes a first region in which the predetermined difference D of the Ta4f peak obtained in this manner is 0.34 or less.

[0082] 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.

[0083] Furthermore, when the absorber film 4 contains multiple tantalums with different oxidation numbers, 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 number 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±0.30eV, Ta ５＋ : 27.0±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.

[0084] 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.

[0085] Pattern transfer onto a semiconductor substrate using an exposure apparatus is performed in a hydrogen atmosphere. Therefore, the reflective mask 200 is placed in a hydrogen atmosphere during exposure for pattern transfer. As a result, hydrogen may penetrate into the absorber film 4 of the reflective mask 200 during exposure and accumulate at grain boundaries, causing stress changes in the absorber film 4. Furthermore, hydrogen that has penetrated into the absorber film 4 may further penetrate into the protective film 3 and / or the multilayer reflective coating 2, causing peeling of the protective film 3 and / or the multilayer reflective coating 2.

[0086] On the other hand, the inventors have found that when the absorber film 4 includes a first region in which the predetermined difference D of the Ta4f peaks is 0.34 or less, as in the absorber film 4 of the present embodiment, Ta is likely to function as a hydrogen trap site. When Ta is likely to function as a hydrogen trap site, it is possible to suppress the accumulation of hydrogen at the grain boundaries of the absorber film 4. Therefore, when the absorber film 4 includes a first region in which the predetermined difference D of the Ta4f peaks is 0.34 or less, it is possible to suppress stress changes in the absorber film 4. Therefore, by having the absorber film 4 include a first region with the predetermined difference D, it is possible to suppress film peeling of the absorber film 4 (absorber pattern 4a), the protective film 3, and / or the multilayer reflective coating 2.

[0087] Specifically, when the absorber film 4 includes a first region in which the predetermined difference D between the Ta4f peaks is 0.34 or less, Ta is likely to function as a trap site for hydrogen. Therefore, even when the reflective mask blank 100 of this embodiment is placed in a hydrogen atmosphere in an exposure tool, it is considered that hydrogen that has penetrated from the surface of the absorber film 4 (absorber pattern 4a) will remain in the surface region of the absorber film 4 (absorber pattern 4a) (for example, within a range of about 20 nm deep from the surface of the absorber film 4). As a result, the penetrated hydrogen is prevented from reaching inter-film interfaces with low adhesion, particularly the interface between the multilayer reflective film 2 and the protective film 3 on the multilayer reflective film 2 and / or the interface between the absorber film 4 and the multilayer reflective film 2 (protective film 3), and therefore it is considered that peeling of the absorber film 4 (absorber pattern 4a), the protective film 3, and / or the multilayer reflective film 2 can be suppressed.

[0088] Therefore, it is preferable that the absorber film 4 has at least a first region in an upper region described below. The upper region extends in the film thickness direction from the outermost surface of the absorber film 4 over a range of 50% of the total film thickness of the absorber film 4. When a reflective mask 200 manufactured from a reflective mask blank 100 using an absorber film 4 having such a configuration is placed in a hydrogen atmosphere, the hydrogen content in the upper region of the absorber film 4 is higher than the hydrogen content in a lower region of the absorber film 4 described below. The lower region of the absorber film 4 extends in the film thickness direction from the interface between the absorber film 4 and the substrate 1 over a range of 50% of the total film thickness of the absorber film 4.

[0089] The difference D is preferably greater than 0, more preferably greater than 0.1, and even more preferably greater than 0.15. When the difference D is in an appropriate range, it is possible to more reliably ensure that Ta functions as a hydrogen trapping site.

[0090] For the reflective mask blank 100 and the reflective mask 200, Power 300 W, H ２When one cycle is defined as irradiating with hydrogen plasma at a flow rate of 100 sccm and 100 sec / cycle, followed by stopping the hydrogen plasma irradiation for 100 seconds, it is preferable that the number of cycles until film peeling occurs in the absorber film 4 (absorber pattern 4 a), protective film 3 or multilayer reflective film 2 of the reflective mask blank 100 and the reflective mask 200 exceeds 50.

[0091] The reason why hydrogen that penetrates from the surface of the absorber film 4 (absorber pattern 4a) can remain in the surface region of the absorber film 4 (absorber pattern 4a) is considered to be as follows. However, the present invention is not limited to this explanation. That is, when the absorber film 4 includes a first region in which the predetermined difference D of the Ta4f peak is 0.34 or less, the Ta4f constituting the Ta4f peak 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. The tantalum (Ta) atom with an imbalance in the electron distribution is believed to function as a hydrogen trap site. Therefore, when the absorber film 4 includes a first region within the range of the predetermined difference D, hydrogen diffusion can be suppressed. Therefore, hydrogen that penetrates from the surface of the absorber film 4 (absorber pattern 4a) can remain in the surface region of the absorber film 4 (absorber pattern 4a). Furthermore, while hydrogen penetrates relatively easily into the grain boundaries in the absorber film 4 (absorber pattern 4a), when the absorber film 4 includes a first region within the range of the predetermined difference D, hydrogen penetration into the grain boundaries can be suppressed.

[0092] 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).

[0093] The first region of the absorber film 4 of the reflective mask blank 100 of this embodiment preferably contains tantalum (Ta) and nitrogen (N). By including tantalum (Ta) and nitrogen (N) in the first region of the absorber film 4, the above-mentioned difference D can be made to fall within a predetermined range when the absorber film 4 is measured by X-ray photoelectron spectroscopy (XPS).

[0094] Furthermore, in the reflective mask blank 100 of this embodiment, the first region of the absorber film 4 preferably contains nitrogen at 12 atomic % or more, more preferably 15 atomic % or more, and particularly preferably 18 atomic % or more. By including a predetermined amount of nitrogen (N) in the first region of the absorber film 4, it is possible to more reliably ensure that the difference D falls within a predetermined range when the absorber film 4 is measured by X-ray photoelectron spectroscopy (XPS). Furthermore, the first region of the absorber film 4 preferably contains nitrogen at 50 atomic % or less, more preferably 45 atomic % or less, and even more preferably 35 atomic % or less. By including a predetermined nitrogen content in the absorber film 4, the absorber film 4 including the first region can have an amorphous structure. As a result, the absorber film 4 becomes smooth and flat, which is preferable. Note that, when the first region of the absorber film 4 contains boron, the nitrogen content is preferably 30 atomic % or less, more preferably 25 atomic % or less, and even more preferably 20 atomic % or less. This allows the absorber film 4 to sufficiently absorb EUV light.

[0095] In the reflective mask blank 100 of this embodiment, the first region of the absorber film 4 preferably contains tantalum (Ta) at 40 atomic % or more, more preferably 50 atomic % or more, and even more preferably 55 atomic % or more. Because tantalum-based materials have high cleaning resistance, the tantalum (Ta) content is preferably a predetermined value or more. In order to improve the processability of the absorber film 4 while maintaining the absorber film 4's ability to absorb EUV light, the upper limit of the tantalum (Ta) content in the first region of the absorber film 4 is preferably 80 atomic % or less, and more preferably 78 atomic % or less.

[0096] In the reflective mask blank 100 of this embodiment, the first region of the absorber film 4 can contain at least one of boron (B), carbon (C), oxygen (O), hydrogen (H), and a noble gas. When the first region of the absorber film 4 contains boron (B), the boron content of the first region can be 3 atomic % or more, preferably 5 atomic % or more, and more preferably 8 atomic % or more. Furthermore, the boron content of the first region of the absorber film 4 is preferably 20 atomic % or less, and more preferably 15 atomic % or less. By including a predetermined content of boron (B) in the first region of the absorber film 4, the smoothness, flatness, and cleaning resistance of the absorber film 4 can be improved while maintaining the effect of absorbing EUV light. When the first region of the absorber film 4 contains nitrogen (N), the boron (B) content of the absorber film 4 can be less than 1 atomic %, and may be below the detection limit.

[0097] The absorber film 4 can be a single-layer film. A single-layer film has the advantage of reducing the number of steps in mask blank manufacturing, thereby improving production efficiency. Alternatively, the absorber film 4 can be a multilayer film composed of multiple films. Figure 3 shows a case where the absorber film 4 includes two layers: a lower absorber film layer 42 and an upper absorber film layer 44. In the case of a multilayer film, the optical constants and film thickness of the upper absorber film layer 44 can be appropriately set so that it serves as an anti-reflection film during optical mask pattern inspection. This improves inspection sensitivity during optical mask pattern inspection. Furthermore, using a film containing oxygen (O) or nitrogen (N), which improves oxidation resistance, as the upper absorber film layer 44 improves stability over time. Thus, by forming the absorber film 4 into a multilayer film, various functions can be added. When the absorber film 4 has a phase shift function, forming the absorber film into a multilayer film allows for a wider range of optical adjustment, making it easier to obtain a desired reflectance. The absorber film lower layer 42 can have the same function as the single-layer absorber film 4. Although the above describes the case where the absorber film 4 includes two layers, the absorber film 4 can also include three or more layers. In this case, for example, it is preferable that the layer with the largest thickness among the three or more layers has the same function as the single-layer absorber film 4.

[0098] The material of the absorber film 4 is not particularly limited as long as it has the function of absorbing EUV light and can be processed by etching or the like. The material of the absorber film 4 is preferably etchable by dry etching using a chlorine (Cl) or fluorine (F)-based gas. As a material having such a function, tantalum (Ta) alone or a tantalum compound containing Ta as a main component can be preferably used.

[0099] When the absorber film 4 includes multiple layers, all of the multiple layers may be made of Ta alone or the above-mentioned tantalum compound. Alternatively, at least one of the multiple layers of the absorber film 4 may be made of Ta alone or the above-mentioned tantalum compound, and the other layers may be made of a material other than Ta alone or the above-mentioned tantalum compound.

[0100] In the case of the absorber film 4 made of tantalum or a tantalum compound, it can be formed by magnetron sputtering such as DC sputtering or RF sputtering. For example, the absorber film 4 can be formed by reactive sputtering using a target containing tantalum and boron and xenon gas to which oxygen or nitrogen is added.

[0101] The tantalum compound for forming the absorber film 4 includes a Ta alloy. When the absorber film 4 is a Ta alloy, the crystalline state of the absorber film 4 is preferably an amorphous or microcrystalline structure in terms of smoothness and flatness. If the surface of the absorber film 4 is smooth and flat, the edge roughness of the absorber pattern 4a will be small and the dimensional accuracy of the pattern will be high. The surface roughness of the absorber film 4 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).

[0102] As the tantalum compound for forming the absorber film 4, a compound containing Ta and B, a compound containing Ta and N, a compound containing Ta and O, a compound containing Ta, O and N, a compound containing Ta and B and further containing at least one of O and N, a compound containing Ta and Si, a compound containing Ta, Si and N, a compound containing Ta and Ge, and a compound containing Ta, Ge and N can be used.

[0103] Ta has a large absorption coefficient for EUV light and is a material that can be easily dry-etched with chlorine-based gas or fluorine-based gas. Therefore, Ta can be said to be a material with excellent processability for the absorber film 4. Furthermore, by adding B, Si, and / or Ge, etc. to Ta, an amorphous material can be easily obtained. As a result, the smoothness of the absorber film 4 can be improved. Furthermore, by adding N and / or O to Ta, the resistance of the absorber film 4 to oxidation is improved, thereby achieving the effect of improving stability over time.

[0104] When the first region of the absorber film 4 contains oxygen, the oxygen content can be 1 atomic % or more. When the first region of the absorber film 4 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 absorber film 4 is located in the outermost surface, surface region, or lower 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 absorber film 4 may be below the detection limit. When the first region of the absorber film 4 is located in the internal region, the first region does not need to contain oxygen.

[0105] The first region of the absorber film 4 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 film thickness direction of the first region may be set as the contents of the constituent atoms in the entire first region. The compositionally graded region includes the surface region, the lower interface region, and the layer interface region.

[0106] The difference D is not necessarily determined solely by the composition of a thin film such as the first region of the absorber film 4. The film density and crystalline state of the thin film also affect the properties of the thin film. Therefore, the conditions for forming a thin film by sputtering are adjusted to form the thin film with the desired properties. 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, and the target formation conditions, are adjusted to form the thin film with the desired properties. Furthermore, these film formation conditions are specific to the film formation apparatus and are adjusted appropriately so that the thin film has the desired properties. As described above, the present invention has an unprecedentedly excellent effect in that it makes it possible to easily select an absorber film 4 that can suppress film peeling by using the difference D rather than the composition, whereas it has been difficult to find an absorber film 4 that can suppress film peeling by using only the composition.

[0107] In order to more effectively suppress film peeling due to hydrogen, it is preferable that the first region extend over at least 50% of the absorber film 4 when viewed from above, more preferably over 80%, and particularly preferably over 100% (the entire surface).

[0108] The sputtering gas used to form the absorber film 4 preferably contains a noble gas. The noble gas may be one selected from He gas, Ne gas, Xe gas, Ar gas, and Kr gas, or a mixture of two or more noble gases selected from these noble gases. When using a noble gas, krypton (Kr) and / or xenon (Xe), which have a larger atomic weight than argon (Ar), can be used to reduce the film stress of the absorber film 4 and improve the flatness of the reflective mask blank 100 and the reflective mask 200. Xenon (Xe) is particularly preferred as the noble gas. When only xenon (Xe) is used, the absorber film 4 contains a very small amount of xenon (Xe) (for example, 3 atomic % or less) and does not contain any other noble gases.

[0109] The absorber film 4 is preferably formed while being heated. This allows the properties of the absorber film 4 to be adjusted within a preferred range. The heating temperature during formation of the absorber film 4 is preferably 100°C or higher, more preferably 120°C or higher, and even more preferably 150°C or higher. In addition, in order to suppress diffusion within the multilayer reflective film 2, the heating temperature is preferably 220°C or lower, and more preferably 200°C or lower. When heating during formation of the absorber film 4, the temperature inside the chamber of the film formation apparatus may be within the above range, and the temperature of the substrate 1 may also be within the above range. The heating means is not particularly limited, and examples thereof include a heater and a hot plate.

[0110] 2 and 3 , the reflective mask blank 100 of this embodiment can have an etching mask film 6 on the absorber film 4. As a material for the etching mask film 6, it is preferable to use a material that has a high etching selectivity ratio of the absorber film 4 to the etching mask film 6. The etching selectivity ratio is a value obtained by dividing the etching rate of the absorber film 4 by the etching rate of the etching mask film 6. The etching selectivity ratio of the absorber film 4 to the etching mask film 6 is preferably 1.5 or more, and more preferably 3 or more.

[0111] The reflective mask blank 100 of this embodiment preferably has an etching mask film 6 on the absorber film 4 .

[0112] Chromium or a chromium compound is preferably used as the material for the etching mask film 6. Examples of chromium compounds include materials containing Cr and at least one element selected from N, O, C, and H. The etching mask film 6 more preferably contains CrN, CrO, CrC, CrON, CrOC, CrCN, and / 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).

[0113] Tantalum or a tantalum compound is preferably used as the material of the etching mask film 6. 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 6 contains TaN, TaO, TaON, TaBN, TaBO, or TaBON.

[0114] Silicon or a silicon compound is preferably used as the material for the etching mask film 6. 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.

[0115] The thickness of the etching mask film 6 is preferably 3 nm or more in order to form a pattern with high precision in the absorber film 4. Moreover, the thickness of the etching mask film 6 is preferably 15 nm or less in order to make the thickness of the resist film 11 thin.

[0116] The etching mask film 6 can be a single-layer film. When the etching mask film 6 is a single-layer film, the number of steps in manufacturing the mask blank can be reduced, which is advantageous in that production efficiency is improved. The etching mask film 6 can also be a multi-layer film made up of multiple layers. When the etching mask film 6 includes multiple layers, the cross-sectional shape of the pattern made up of the etching mask film 6 can be made better.

[0117] The reflective mask blank 100 of this embodiment preferably has an etching mask film 6 including two or more layers on the absorber film 4. By including two or more layers of an appropriate material in the etching mask film 6, the thickness of the resist film 11 can be reduced when forming the absorber pattern 4a, allowing for the formation of a finer absorber pattern 4a. Furthermore, when the etching mask film 6 includes two or more layers, it is preferable that the layer farthest from the substrate 1 among the two or more layers has a smaller thickness than the other layers. For example, when the etching mask film 6 consists of an upper layer and a lower layer, it is preferable that the thickness of the upper layer is smaller than the thickness of the lower layer. This allows for the formation of an etching mask pattern 6a with a better cross-sectional shape.

[0118] In the reflective mask blank 100 of this embodiment, the etching mask film 6 preferably contains ruthenium. When the etching mask film 6 is composed of two layers, for example, a lower layer (a layer in contact with the absorber film 4) and an upper layer formed on the lower layer, the lower layer preferably contains ruthenium. By including ruthenium in the etching mask film 6 (lower layer), protection of the non-etched portions of the absorber film 4 can be more reliably achieved when forming the absorber pattern 4a. Furthermore, when the etching mask film 6 contains ruthenium, it may further contain at least one metal selected from chromium (Cr), tantalum (Ta), rhodium (Rh), niobium (Nb), zirconium (Zr), titanium (Ti), molybdenum (Mo), yttrium (Y), and lanthanum (La). Furthermore, the etching mask film 6 containing ruthenium may further contain at least one element selected from boron, nitrogen, oxygen, carbon, and hydrogen. The upper layer may also contain chromium instead of ruthenium. The etching mask film 6 as described above can more reliably protect the absorber film 4 containing tantalum.

[0119] In the reflective mask blank 100 of this embodiment, the etching mask film 6 preferably contains tantalum. When the etching mask film 6 is composed of, for example, two layers, a lower layer and an upper layer, the upper layer preferably contains tantalum. When the upper layer contains tantalum, the upper layer may further contain at least one element selected from boron, nitrogen, oxygen, carbon, and hydrogen. The material of the upper layer may be, for example, TaO, TaN, TaB, TaON, TaBO, or TaBN. Tantalum is easily etched. Therefore, if the upper layer of the etching mask film 6 contains tantalum, an upper layer pattern with a good cross-sectional shape can be formed. Then, by forming a lower layer pattern using this upper layer pattern as a mask, the unetched portions of the lower layer can be more reliably protected, and the cross-sectional shape of the lower layer pattern can also be improved. Using an etching mask film 6 including such upper and lower layers enables the formation of a more accurate absorber pattern.

[0120] <Reflective mask 200> This embodiment is a reflective mask 200 comprising an absorber pattern 4a obtained by patterning the absorber film 4 of the above-described reflective mask blank 100. That is, as shown in Fig. 4E, the reflective mask 200 of this embodiment comprises a substrate 1, a multilayer reflective film 2 formed on the substrate 1, and an absorber pattern 4a formed on the multilayer reflective film 2.

[0121] 4A to 4E are schematic cross-sectional 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.

[0122] First, a reflective mask blank 100 is prepared, which includes a substrate 1, a multilayer reflective film 2, an absorber film 4, and an etching mask film 6. The reflective mask blank 100 may have a protective film 3. Next, a resist film 11 is formed on the etching mask film 6, thereby obtaining a reflective mask blank 100 with the resist film 11 (FIG. 4A). A pattern is written on the resist film 11 using an electron beam lithography device, and a development and rinsing process is then performed to form a resist pattern 11a (FIG. 4B).

[0123] Next, the etching mask film 6 is dry-etched using the resist pattern 11a as a mask. As a result, the portions of the etching mask film 6 that are not covered by the resist pattern 11a are etched, forming an etching mask pattern 6a (FIG. 4C). The resist pattern 11a is then removed with a resist remover.

[0124] Next, using the etching mask pattern 6a as a mask, the absorber film 4 is dry-etched, whereby the portions of the absorber film 4 that are not covered by the etching mask pattern 6a are etched, and the absorber pattern 4a is formed (FIG. 4D).

[0125] As an etching gas for the absorber film 4, 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 ３In 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.

[0126] After the absorber pattern 4a is formed, the etching mask pattern 6a is removed by dry etching. After the etching mask pattern 6a 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. 4E).

[0127] The reflective mask 200 thus obtained has a structure in which a multilayer reflective film 2, a protective film 3, and an absorber pattern 4a are laminated on a substrate 1.

[0128] An area (reflective area) where the protective film 3 formed on the multilayer reflective film 2 is exposed has the function of reflecting EUV light. An area where the multilayer reflective film 2 and the protective film 3 are covered with the absorber pattern 4 a has the function of absorbing EUV light. The reflective mask 200 of this embodiment is a reflective mask 200 that can suppress film peeling, and therefore can transfer finer patterns onto a transfer target in EUV lithography.

[0129] The protective film 3 in the region exposed by forming the absorber pattern 4a may be finally removed. On the other hand, if the function of the reflective mask 200 is not affected even if the protective film 3 remains, then there is no need to particularly remove the protective film 3. Furthermore, when the reflective mask 200 is manufactured using the reflective mask blank 100 having a configuration including the above-described etching mask film 6, the etching mask film 6 may finally be removed. On the other hand, if the function of the reflective mask 200 is not affected even if the etching mask film 6 remains, then there is no need to particularly remove the etching mask film 6.

[0130] The absorber pattern 4 a of the reflective mask 200 of this embodiment, like the reflective mask blank 100 of this embodiment described above, has a Ta4f spectrum normalized by the maximum intensity value of the Ta4f peak, which is obtained by analyzing the absorber pattern 4 a by X-ray photoelectron spectroscopy. ５／２ Peak and Ta4f ７／２ The minimum intensity value between the peaks and Ta4f ５／２ Peak and Ta4f ７／２ The first region includes a first region in which the difference D between the interpolated value of the intensity at the minimum binding energy on the linear interpolation function obtained by linear interpolation based on the peaks is 0.34 or less.

[0131] As with the reflective mask blank 100 of the present embodiment described above, the first region of the absorber pattern 4a of the reflective mask 200 of the present embodiment preferably contains tantalum (Ta) and nitrogen (N).

[0132] Similarly to the reflective mask blank 100 of this embodiment described above, the first region of the absorber pattern 4 a of the reflective mask 200 of this embodiment preferably contains nitrogen at a concentration of 12 atomic % or more, more preferably 15 atomic % or more, and particularly preferably 18 atomic % or more. The first region of the absorber pattern 4 a preferably contains nitrogen at a concentration of 50 atomic % or less, more preferably 45 atomic % or less, and even more preferably 35 atomic % or less. When the first region of the absorber pattern 4 a contains boron, the nitrogen content is preferably 30 atomic % or less, more preferably 25 atomic % or less, and even more preferably 20 atomic % or less.

[0133] Similarly to the reflective mask blank 100 of this embodiment described above, the protective film 3 of the reflective mask 200 of this embodiment preferably includes a protective film 3 between the multilayer reflective film 2 and the absorber film 4, the protective film 3 including a lower layer and an upper layer formed on the lower layer. When the protective film 3 includes a lower layer and an upper layer, the upper layer of the protective film 3 preferably contains ruthenium. When the protective film 3 includes a lower layer and an upper layer, the lower layer of the protective film 3 preferably contains a first metal different from ruthenium (Ru), and the upper layer preferably contains a second metal different from both ruthenium (Ru) and the first metal. The lower layer of the protective film 3 may contain ruthenium (Ru) in addition to the first metal. Alternatively, the lower layer of the protective film 3 may contain ruthenium (Ru), and the upper layer may contain a second metal.

[0134] The reflective mask 200 of this embodiment has the predetermined absorber pattern 4a as described above, and therefore, peeling of the absorber pattern 4a, the protective film 3 and / or the multilayer reflective film 2 can be suppressed.

[0135] <Method for Manufacturing Semiconductor Device> The method for manufacturing a semiconductor device according to this embodiment is a method for manufacturing a semiconductor device that includes a step of transferring the absorber pattern 4a of the above-described reflective mask 200 onto a transfer target on a semiconductor substrate.

[0136] The method for manufacturing a semiconductor device according to this embodiment includes a step of performing a lithography process using an EUV exposure apparatus 50 with the reflective mask 200 having a pattern formed on the absorber film 4 described above, and transferring the absorber pattern 4a to a transfer target on a semiconductor substrate, thereby forming a transfer pattern. Fig. 5 is a schematic diagram showing an example of the EUV exposure apparatus 50.

[0137] 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.

[0138] The reflective mask 200 of this embodiment has a predetermined absorber pattern 4a, and can therefore suppress peeling of the absorber pattern 4a, the protective film 3, and / or the multilayer reflective film 2. Therefore, by using the reflective mask 200 of this embodiment, it is possible to increase the density and precision of semiconductor devices.

[0139] 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.

[0140] 5 shows a schematic configuration of an EUV exposure apparatus 50, which is an apparatus for transferring a transfer pattern onto a resist film 11 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.

[0141] 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.

[0142] The EUV light reflected by the reflective mask 200 is reduced by the projection optical system 57 to a pattern image light, usually 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 the resist film 11 on the semiconductor substrate 60. By developing the exposed resist film 11, a resist pattern 11a can be formed on the semiconductor substrate 60. By etching the semiconductor substrate 60 using the resist pattern 11a as a mask, an integrated circuit pattern can be formed on the semiconductor substrate 60. A semiconductor device is manufactured through these and other necessary steps.

[0143] Examples will be described below, but the present invention is not limited to these examples.

[0144] In Examples 1 to 6 and Comparative Examples 1 to 3, a reflective mask blank 100 was fabricated in which a multilayer reflective film 2, a protective film 3, an absorber film 4, and an etching mask film 6 were formed on one main surface (first main surface) of a substrate 1. A back surface conductive film 5 was formed on the other main surface (second main surface) of the substrate 1 of the reflective mask blank 100. Thereafter, the reflective mask blanks 100 of Examples 1 to 6 and Comparative Examples 1 to 3 were used to fabricate reflective masks 200 of Examples 1 to 6 and Comparative Examples 1 to 3.

[0145] (Reflective mask blank 100) Table 1 shows the compositions of the multilayer reflective film 2, protective film 3, absorber film 4 and etching mask film 6 of the reflective mask blanks 100 of the Examples and Comparative Examples. The reflective mask blanks 100 of the Examples and Comparative Examples were produced as follows.

[0146] The two main surfaces of the SiO 6025 size (approximately 152 mm × 152 mm × 6.35 mm) low thermal expansion glass substrate 1 are polished. ２ -TiO ２ A glass substrate 1 was prepared as the substrate 1. To obtain a flat and smooth main surface, polishing was carried out through a rough polishing process, a precision polishing process, a local polishing process, and a touch polishing process.

[0147] Next, SiO ２ -TiO ２ A back surface conductive film 5 made of a CrN film was formed by magnetron sputtering (reactive sputtering) on ​​the main surface (back surface) of the glass substrate 1. The back surface conductive film 5 was formed to a thickness of 70 nm using a Cr target in a nitrogen gas atmosphere.

[0148] Next, a multilayer reflective film 2 was formed on the main surface (first main surface) of the substrate 1. The multilayer reflective film 2 formed on the substrate 1 was a periodic multilayer reflective film made of molybdenum (Mo) and silicon (Si) to be suitable for EUV light with a wavelength of 13.5 nm. The multilayer reflective film 2 was formed by alternately stacking Mo layers and Si layers on the substrate 1 by ion beam sputtering in a krypton (Kr) gas atmosphere using a Mo target and a Si target. First, a Si film was formed to a thickness of 4.2 nm, followed by a Mo film to a thickness of 2.8 nm. This constitutes one cycle, and 40 cycles were similarly stacked. Finally, a Si film was formed to a thickness of 4.0 nm to form the multilayer reflective film 2.

[0149] Next, a protective film 3 was formed on the multilayer reflective film 2. In the reflective mask blanks 100 of Examples 1 and 3 to 6 and Comparative Examples 1 to 3, a RuNb target (Ru: 80 atomic %, Nb: 20 atomic %) was used and the protective film 3 made of a RuNb film was formed on the multilayer reflective film 2 by DC magnetron sputtering in an Ar gas atmosphere. The thickness of the protective film 3 was 3.5 nm.

[0150] In the reflective mask blank 100 of Example 2, a two-layer protective film 3 was formed, consisting of a lower RuNb film and an upper RuRhN film. As the lower layer of the protective film 3, a RuNb film with a thickness of 2 nm was formed under the same film formation conditions as those for the protective film 3 (RuNb film) of the reflective mask blank 100 of Examples 1 and 3 to 6 and Comparative Examples 1 to 3. As the upper layer of the protective film 3, a RuNb film was formed under the same film formation conditions as those for the protective film 3 (RuNb film) of the reflective mask blank 100 of Examples 1 and 3 to 6 and Comparative Examples 1 to 3. ２ In a gas atmosphere, a RuRhN film having a thickness of 2 nm was formed by DC magnetron sputtering (reactive sputtering) using a RuRh target (Ru:Rh=60 at %:30 at %).

[0151] Next, a predetermined absorber film 4 was formed on the protective film 3. In the reflective mask blanks 100 of Examples 1, 2, and 5 and Comparative Example 3, an absorber film 4 consisting of one layer was formed. In the reflective mask blanks 100 of Examples 3 and 4 and Comparative Examples 1 and 2, an absorber film 4 consisting of two layers, an absorber film lower layer 42 and an absorber film upper layer 44, was formed. The films were formed in the order of the absorber film lower layer 42 and the absorber film upper layer 44. In the reflective mask blank 100 of Example 6, an absorber film 4 consisting of three layers, the absorber film lower layer, the absorber film lower layer 42, and the absorber film upper layer 44, was formed. The films were formed in the order of the absorber film lower layer, the absorber film lower layer 42, and the absorber film upper layer 44.

[0152] Table 1 shows the film thickness, composition, and deposition gas of the absorber film 4 of the examples and comparative examples. ２ " refers to Xe gas and N ２ It means a mixed gas with Ar+O ２ " refers to Ar gas and O ２ It means a mixture of gases.

[0153] The absorber films 4 (the bottom layer of the absorber film, the lower layer 42 of the absorber film, and the upper layer 44 of the absorber film) in the examples and comparative examples were formed on the protective film 3 by DC magnetron sputtering (reactive sputtering) to have the thin film thickness and composition shown in Table 1. As the target, a Ta target or a TaB target was used to obtain the predetermined composition, and the film was formed using the film formation gas shown in Table 1. In each example, the chamber of the film formation apparatus was preheated and the absorber film 4 was formed while the temperature inside the chamber was maintained at 150°C. However, in Example 6, the bottom layer of the absorber film 4 was formed without preheating the chamber of the film formation apparatus, while the lower layer 42 of the absorber film and the upper layer 44 of the absorber film were formed while the temperature inside the chamber was maintained at 150°C.

[0154] Next, a predetermined etching mask film 6 was formed on the absorber film 4 of each of the examples and comparative examples. In the reflective mask blanks 100 of Example 6 and Comparative Examples 1 and 2, an etching mask film 6 consisting of one layer was formed. In Table 1, the composition and film thickness of the etching mask films 6 of Example 6 and Comparative Examples 1 and 2 are shown in the columns for lower layer composition and lower layer film thickness, respectively. In the reflective mask blanks 100 of Examples 1 to 5 and Comparative Example 3, an etching mask film 6 consisting of two layers, a lower layer and an upper layer, was formed. The films were formed in the order of the lower layer and the upper layer.

[0155] The CrOCN film, which is the etching mask film 6 in Example 6 and Comparative Examples 1 and 2, was formed using a target containing Cr and a sputtering gas of Ar containing CO. ２ and N ２ The CrOCN film was formed by DC magnetron sputtering (reactive sputtering) using a sputtering gas containing Ru. The thickness of the CrOCN film was 10 nm. The composition of the RuCrON film that is the lower layer of the etching mask film 6 in Examples 1 to 5 and Comparative Example 3 was Ru:Cr:O:N=73 at %:9 at %:12 at %:6 at %, and the thickness was 10 nm. The TaBN film that is the upper layer of the etching mask film 6 in Examples 1 to 5 and Comparative Example 3 was formed using a target containing TaB and a sputtering gas containing Xe and N. ２ The TaBN film was formed by DC magnetron sputtering (reactive sputtering) using a sputtering gas containing Ta, B, and N. The composition of the TaBN film was Ta:B:N=75 at %:14 at %:11 at %, and the film thickness was 4 nm.

[0156] In this manner, the reflective mask blanks 100 of Examples 1 to 6 and Comparative Examples 1 to 3 were manufactured.

[0157] <Measurement by X-ray photoelectron spectroscopy (XPS method)> The Ta4f spectra of the absorber films 4 of the reflective mask blanks 100 of Examples 1 to 6 and Comparative Examples 1 to 3 were analyzed by X-ray photoelectron spectroscopy (XPS method). Specifically, by XPS method, the binding energies in the range of 15 eV to 35 eV of photoelectrons excited by X-rays irradiated onto the absorber films 4 of the reflective mask blanks 100 of Examples 1 to 6 and Comparative Examples 1 to 3 and emitted to the outside were measured, thereby obtaining the photoelectron energy distribution (Ta4f peak).

[0158] In the analysis of the absorber film 4 by X-ray photoelectron spectroscopy (XPS), a multilayer reflective film 2, a protective film 3, and an absorber film 4 were formed on one main surface of the substrate 1 under the same conditions as in Examples 1 to 6 and Comparative Examples 1 to 3 described above. Next, X-rays were irradiated from an X-ray source toward the surface of the absorber film 4 of each Example and Comparative Example, and the energy distribution of photoelectrons emitted from the surface of the absorber film 4 was measured. Next, the absorber film 4 was excavated by approximately 1 nm per measurement using Ar gas sputtering, and the surface of the absorber film 4 in the excavated region was measured by XPS. This measurement was repeated throughout the entire depth direction of the absorber film 4, thereby analyzing the entire depth direction of the absorber film 4. The measurement conditions for the X-ray photoelectron spectroscopy analysis were as follows: 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

[0159] The detection depth by the XPS method is approximately 4 to 5 nm. Therefore, the above-mentioned XPS analysis was able to obtain information about the inside of the absorber film 4 in the depth direction. Furthermore, from the results of the above-mentioned XPS analysis, it was determined whether the absorber film 4 had a first region in which the predetermined difference D was 0.34 or less.

[0160] The absorber films 4 of Examples 1, 2, and 5 and Comparative Example 3 were formed without changing the film formation conditions in each film thickness direction. Therefore, it is believed that the absorber films 4 of Examples 1, 2, and 5 and Comparative Example 3 have uniform (uniform) characteristics that do not change in the film thickness direction, except for the lower interface region and the surface region. Therefore, when determining whether the absorber film 4 has the first region, the determination was made by obtaining a Ta4f spectrum at a specific depth position within the internal region as a result of measurement and analysis using a predetermined XPS method. More specifically, in Examples 1, 2, and 5 and Comparative Example 3, it was determined that the absorber film 4 has the first region when the predetermined difference D was 0.34 or less at a depth position 10 minutes after the start of etching (at one location within a depth of approximately 10 to 15 nm).

[0161] Furthermore, in Examples 3, 4, and 6 and Comparative Examples 1 and 2, the absorber film lower layer 42 was formed without changing the film formation conditions in each thickness direction. Therefore, it was considered that the absorber film lower layer 42 had uniform characteristics that did not change in the thickness direction, except for the lower interface region and the layer interface region. The layer interface region here refers to the vicinity of the interface between the absorber film lower layer 42 and the absorber film upper layer 44 and the vicinity of the interface between the absorber film lower layer 42 and the bottom layer of the absorber film. Therefore, in Examples 3, 4, and 6 and Comparative Examples 1 and 2, the absorber film lower layer 42 was determined to have a first region if the predetermined difference D was 0.34 or less at at least one location within the internal region of the absorber film lower layer 42, within a depth range of approximately 10 to 15 nm from the interface between the absorber film lower layer 42 and the absorber film upper layer 44. Furthermore, the thicknesses of the absorber film upper layer 44 in Examples 3, 4, and 6 and Comparative Examples 1 and 2 and the bottom layer of the absorber film in Example 6 were very small. For this reason, when the predetermined difference D is 0.34 or less at the center position in the film thickness direction, it is determined that the absorber film upper layer 44 or the bottom layer of the absorber film has the first region. Note that when the absorber film 4 includes the absorber film lower layer 42 and the absorber film upper layer 44, it is sufficient that at least one of the absorber film lower layer 42 and the absorber film upper layer 44 includes the first region. When the absorber film 4 includes the absorber film lower layer 42 and the absorber film upper layer 44, it is also sufficient that at least one of the absorber film lower layer 42 and the absorber film upper layer 44 includes the first region.

[0162] 6 illustrates a spectrum including the Ta4f peak of the absorber film 4. The horizontal axis (Binding Energy) of FIG. 6 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 approximately in the range of 20 eV to 30 eV. The Ta4f peak has a peak at around 24 eV. ５／２ peak, and Ta4f peak at around 22 eV ７／２ It consists of two peaks.

[0163] 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.

[0164] Next, the normalized Ta4f spectrum 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 A straight line L passing through the maximum values ​​of the two peaks was calculated. As shown in FIG. 6, 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.

[0165] Next, as shown in FIG. 6, 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.

[0166] Next, as shown in FIG. 6, the interpolated value (intensity value I Ｄ ) and the minimum intensity value I ｍｉｎ The difference D between these values ​​was calculated.

[0167] 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 between the absorber film 4 and the absorber film 4 is shown. The difference D may be calculated over the entire thickness of the internal region of the absorber film 4 (lowest absorber film layer, absorber film lower layer 42, absorber film upper layer 44), and the average value of the difference D in the depth direction may be used as the difference D of the absorber film 4 (lowest absorber film layer, absorber film lower layer 42, absorber film upper layer 44). Even if the thickness of the absorber film upper layer 44 is very small, the average value of the difference D in the depth direction over the entire absorber film upper layer 44 may be used as the difference D of the absorber film upper layer 44. The same applies to the bottom layer of the absorber film.

[0168] <Reflective Mask 200> Reflective masks 200 were manufactured using the reflective mask blanks 100 of Examples 1 to 6 and Comparative Examples 1 to 3. The manufacture of the reflective mask 200 will be described with reference to Figures 4A to 4E.

[0169] First, as shown in Fig. 4A, a resist film 11 was formed on the absorber film 4 of the reflective mask blank 100 of each of the examples and comparative examples (Fig. 4A). A predetermined pattern was then drawn (exposed) on this resist film 11, and the resist film 11 was further developed and rinsed to form a resist pattern 11a (Fig. 4B).

[0170] Next, the etching mask film 6 was dry-etched using the resist pattern 11a as a mask to form an etching mask pattern 6a (FIG. 4C). ２ Gas and O ２ The etching mask film 6 (CrOC film) was dry-etched using a mixed gas of CF ４ The upper layer (TaBN film) of the etching mask film 6 is dry-etched using a mixture of Cl gas and He gas. ２ Gas and O ２The lower layer (RuCrON film) of the etching mask film 6 was dry-etched using a mixed gas of the above gas.

[0171] Here, when the cross-sectional shapes of the etching mask patterns 6a of the Examples and Comparative Examples were confirmed, Examples 1 to 5 and Comparative Example 3 were better than Example 6, and Comparative Examples 1 and 2. Furthermore, the etching mask patterns 6a of Examples 1 to 5 and Comparative Example 3 had higher cleaning resistance than those of Example 6, and Comparative Examples 1 and 2.

[0172] Next, the absorber film 4 was dry-etched using the etching mask pattern 6a as a mask to form an absorber pattern 4a (FIG. 4D). Specifically, when the reflective mask blanks 100 of Examples 1, 2, and 5 and Comparative Example 3 were used, Cl ２ When the reflective mask blank 100 of Example 3 was used, the absorber film 4 (TaN film) was dry-etched using CF ４ The absorber film upper layer 44 (TaO film) was dry-etched using a mixture of Cl gas and He gas. ２ When the reflective mask blanks 100 of Examples 4 and 6 and Comparative Examples 1 and 2 were used, CF ４ The absorber film upper layer 44 (TaBO film) was dry-etched using a mixture of Cl gas and He gas. ２ In Example 6, after etching the absorber film lower layer 42, the bottom layer of the absorber film (TaBN film) was dry-etched using Cl gas. ２ Dry etching was performed using gas.

[0173] Thereafter, the etching mask pattern 6a was removed by dry etching (FIG. 4E).

[0174] Finally, wet cleaning was performed using deionized water (DIW), and the reflective masks 200 of Examples 1 to 6 and Comparative Examples 1 to 3 were manufactured.

[0175] <Evaluation of Film Peeling> An EUV exposure apparatus is used to transfer a pattern onto a transfer target such as a semiconductor substrate 60 using the reflective mask 200. In the EUV exposure apparatus, the reflective mask 200 is set in an EUV scanner, hydrogen is introduced into the EUV exposure apparatus, and EUV exposure is performed in a hydrogen atmosphere. Therefore, the performance of the reflective mask 200 of this embodiment was evaluated by simulating the environment inside the EUV exposure apparatus during EUV exposure.

[0176] Specifically, the reflective masks 200 of Examples 1 to 6 and Comparative Examples 1 to 3 were placed in a hydrogen plasma irradiation device. ２ Hydrogen plasma was irradiated onto the reflective mask 200 at a flow rate of 100 sccm and 100 sec / cycle, and then the hydrogen plasma irradiation was stopped for 100 seconds. This cycle of starting and stopping the hydrogen plasma irradiation was counted as one cycle, and the number of cycles until film peeling (blistering) occurred in the absorber film 4 (absorber pattern 4a), protective film 3, or multilayer reflective film 2 of the reflective mask 200 was measured. The greater the number of cycles, the less likely blisters were to occur. The measurement results are shown in the column "Number of hydrogen plasma irradiation cycles at which blisters occurred" in Table 1.

[0177] As is clear from Table 1, the number of hydrogen plasma irradiation cycles at which blisters occurred for the reflective masks 200 of Examples 1 to 6 exceeded 50, which was higher than that for the reflective masks 200 of Comparative Examples 1 to 3. The number of hydrogen plasma irradiation cycles at which blisters occurred for the reflective masks 200 of Examples 1 to 6 was improved, for example, by at least 25% compared to Comparative Example 1 and by at least approximately 43% compared to Comparative Example 2. Therefore, it was revealed that the reflective masks 200 of Examples 1 to 6 can suppress peeling of the absorber film 4 (absorber pattern 4a), protective film 3, and multilayer reflective film 2. Furthermore, the reflective mask 200 of Example 2, which has a protective film 3 consisting of upper and lower layers, had a higher number of hydrogen plasma irradiation cycles at which blisters occurred, even compared to Example 1, which had the same configuration except for the protective film 3. That is, it was revealed that the reflective mask 200 of Example 2 can more effectively suppress blister generation due to the configuration of the protective film 3.

[0178] The primary ion species is Cs ＋ The absorber film 4 was analyzed in an arbitrary 124 μm square region within a 5 cm square including the center of the substrate 1 by dynamic secondary ion mass spectrometry under conditions of a primary acceleration voltage of 3.0 kV, a primary ion current of 25 nA, and negative ion detection mode. As a result, in the absorber film 4 of each example, the secondary ion intensity of hydrogen in the upper region was higher than the secondary ion intensity of hydrogen in the lower region. That is, the hydrogen content in the upper region of the absorber film 4 of each example was higher than the hydrogen content in the lower region of the absorber film 4. From this, it can be said that the reflective masks 200 of Examples 1 to 6 can suppress film peeling of the absorber film 4 (absorber pattern 4 a), the protective film 3, and the multilayer reflective film 2.

[0179] <Manufacturing of Semiconductor Device> The reflective mask 200 of Examples 1 to 6 was set in an EUV scanner, and EUV exposure was performed on a wafer having a processed 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 could be formed with high precision on the semiconductor substrate 56 having the processed film formed thereon.

[0180] When semiconductor devices were manufactured using the reflective masks 200 of Examples 1 to 6, 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 enabling semiconductor devices having the desired characteristics to be manufactured with a high yield.

[0181]

[0182] REFERENCE SIGNS LIST 1 substrate 2 multilayer reflective film 3 protective film 4 absorber film 4a absorber pattern 5 back surface conductive film 6 etching mask film 6a etching mask pattern 11 resist film 11a resist pattern 42 absorber film lower layer 44 absorber film 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, a multilayer reflective film formed on the substrate, and an absorber film formed on the multilayer reflective film, wherein the absorber film includes a first region in a Ta4f spectrum normalized by a maximum intensity value of a Ta4f peak obtained by analyzing the absorber film by X-ray photoelectron spectroscopy, and 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 is 0.34 or less. ５／２ peak and Ta4f ７／２ peak, and the Ta4f ５／２ peak and the Ta4f ７／２ reflective mask blank, characterized in that the peak includes the first region.

2. The reflective mask blank according to claim 1, wherein the first region contains tantalum and nitrogen.

3. The reflective mask blank according to claim 1 or 2, wherein the first region contains 12 atomic % or more of nitrogen.

4. The reflective mask blank according to claim 1 or 2, further comprising a protective film including a lower layer and an upper layer formed on the lower layer, between the multilayer reflective film and the absorber film.

5. The reflective mask blank according to claim 4, wherein the upper layer of the protective film contains ruthenium.

6. The reflective mask blank according to claim 1 or 2, further comprising an etching mask film including two or more layers, on the absorber film.

7. The reflective mask blank according to claim 6, wherein the etching mask film contains ruthenium.

8. The reflective mask blank according to claim 6, wherein the etching mask film contains tantalum.

9. A substrate, a multilayer reflective film formed on the substrate, and an absorber pattern formed on the multilayer reflective film, wherein the absorber pattern includes a first region in a Ta4f spectrum normalized by a maximum intensity value of a Ta4f peak obtained by analyzing the absorber pattern by X-ray photoelectron spectroscopy, and a difference D between a minimum intensity value between a Ta4f peak and a Ta4f peak and an interpolated value of the intensity at the binding energy of the minimum intensity on a linear interpolation function obtained by linear interpolation based on the Ta4f peak and the Ta4f peak is 0.34 or less. ５／２ peak and Ta4f ７／２ peak, and the Ta4f ５／２ peak and the Ta4f ７／２ reflective mask, characterized in that it includes a first region where the difference D between the minimum intensity value between the peak and the Ta4f peak and the interpolated value of the intensity at the binding energy of the minimum intensity on a linear interpolation function obtained by linear interpolation based on the Ta4f peak and the Ta4f peak is 0.34 or less.

10. The reflective mask according to claim 9, wherein the first region contains tantalum and nitrogen.

11. The reflective mask according to claim 9 or 10, wherein the first region contains 12 atomic % or more of nitrogen.

12. The reflective mask according to claim 9 or 10, further comprising a protective film including a lower layer and an upper layer formed on the lower layer, between the multilayer reflective film and the absorber film.

13. The reflective mask according to claim 12, wherein the upper layer of the protective film contains ruthenium.

14. A method of manufacturing a semiconductor device, comprising transferring the absorber pattern of the reflective mask according to claim 9 or 10 onto a transfer target on a semiconductor substrate.

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