Substrate with multilayer reflective film, reflective mask blank, reflective mask, and method for producing semiconductor device

Abstract

[Problem] The present invention addresses the problem of improving the adhesion between a first layer and a second layer in a substrate with a multilayer reflective film, the substrate having a protective film that comprises the first layer and the second layer. [Solution] The present invention provides a substrate with a multilayer reflective film, which comprises the substrate, the multilayer reflective film and a protective film that comprises a first layer and a second layer. This substrate with a multilayer reflective film is characterized in that: the protective film contains at least one metal element Em which has a Fermi level of -4.7 eV or less and at least one additive element Ea which has a Fermi level of more than -4.7 eV; and with respect to the distribution of the contents of components contained in the protective film with respect to the position x in the film thickness direction of the protective film, if an inflection point x1 is the position x at which a switch is made between the second layer component dominant state to the first layer component dominant state, M is the content of the metal element Em, and A is the content of the additive element Ea, the ratio A / M at the inflection point x1 is 0.020 or more.

Description

Substrate with multilayer reflective film, 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 a semiconductor device, a multilayer reflective film-coated substrate used for the manufacture of a reflective mask, and a reflective mask blank. 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 optical 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.

[0004] Patent Document 1 describes a reflective mask blank for manufacturing a reflective mask. Specifically, Patent Document 1 describes a reflective mask blank having a substrate, a multilayer reflective film formed on the substrate and reflecting exposure light, a protective film formed on the multilayer reflective film and protecting the multilayer reflective film, and an absorber film formed on the protective film and absorbing exposure light. Patent Document 1 also describes that the protective film of the reflective mask blank is made of a ruthenium compound containing ruthenium (Ru) and at least one selected from molybdenum (Mo), niobium (Nb), zirconium (Zr), yttrium (Y), boron (B), titanium (Ti), and lanthanum (La).

[0005] Japanese Patent Application Laid-Open No. 2005-268750

[0006] 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, 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.

[0007] A reflective mask having an absorber pattern is used in EUV lithography. EUV light irradiated onto the reflective mask is absorbed in the areas where the absorber pattern is present and reflected in the areas where the absorber pattern is not present. A multilayer reflective film is exposed in the 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 (the 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.

[0008] Generally, a multilayer reflective film is used in which elements with different refractive indices are periodically stacked. For example, a Mo / Si periodic stacked film is used as a multilayer reflective film for EUV light with a wavelength of 13 to 14 nm (e.g., 13.5 nm), in which Mo films with a low refractive index and Si films with a high refractive index are alternately stacked for 40 to 60 periods.

[0009] In order to achieve high density and high precision in semiconductor devices using a reflective mask, it is necessary for the reflective region of the reflective mask (the surface of the multilayer reflective film) to have high reflectivity with respect to EUV light, which is the exposure light.

[0010] In the manufacturing process of a reflective mask, when an absorber pattern is formed, the absorber film is etched through a resist pattern or an etching mask pattern. To process the absorber film into the designed shape, it is necessary to perform some over-etching on the absorber film. During over-etching, the multilayer reflective film below the absorber film is also damaged by the etching. To prevent the multilayer reflective film from being damaged by the etching, a protective film is provided between the absorber film and the multilayer reflective film. Therefore, the protective film must have high resistance to the etching gas used to etch the absorber film.

[0011] Metals such as Ru or RuNb are used as materials for protective films that have high resistance to the etching gas used to etch the absorber film. On the other hand, if the outermost surface of a multilayer reflective film is a low-refractive index layer such as a Mo film, the low-refractive index layer is easily oxidized. Oxidation of the low-refractive index layer can reduce the reflectivity of the reflective mask. To prevent oxidation of the low-refractive index layer, a silicon-containing layer, such as a Si film, can be disposed on the outermost surface of the multilayer reflective film. Since this silicon-containing layer is a thin film that protects the multilayer reflective film from oxidation, it is treated as part of the protective film in this specification. In this specification, a thin film included in a protective film that protects the multilayer reflective film from oxidation, such as a silicon-containing layer, is referred to as a "first layer." Furthermore, among the above-mentioned protective films, a thin film that has high resistance to the etching gas used to etch the absorber film is referred to as a "second layer." Generally, the first layer is disposed on the multilayer reflective film, and the second layer is disposed on the first layer.

[0012] In the case where the protective film of the multilayer reflective film-coated substrate has a structure in which a second layer containing a metal material is disposed on a first layer (e.g., a Si thin film) on the multilayer reflective film, when the multilayer reflective film-coated substrate or the like is subjected to a heat treatment in the manufacturing process of a reflective mask, a phenomenon may occur in which the reflectivity of the multilayer reflective film-coated substrate including the multilayer reflective film to EUV light decreases. Note that the heat treatment of the multilayer reflective film-coated substrate or the reflective mask blank is generally sometimes performed for the purpose of adjusting the stress of the multilayer reflective film-coated substrate or the reflective mask blank.

[0013] As described above, when a multilayer reflective film substrate has a structure in which a second layer is disposed on a first layer containing, for example, Si, heat treatment during the manufacturing process of the reflective mask may cause a phenomenon in which the reflectivity of the multilayer reflective film substrate to EUV light decreases. This is thought to be due to the diffusion of silicon from the first layer into the second layer. To prevent a decrease in the reflectivity of the multilayer reflective film substrate, it is necessary to prevent the silicon from diffusing from the first layer into the second layer. To prevent the silicon from diffusing from the first layer into the second layer, it is possible to nitridize and / or oxidize the surface of the first layer (the interface between the first layer and the second layer). However, it has been found that nitriding and / or oxidizing the surface of the first layer (the interface with the second layer) can cause a problem of reduced adhesion between the first layer and the second layer.

[0014] Therefore, an object of the present invention is to provide a multilayer reflective film-coated substrate having a protective film including a first layer for protecting the multilayer reflective film from oxidation and a second layer having high resistance to an etching gas used in etching the absorber film, thereby improving adhesion between the first layer and the second layer.An object of the present invention is to provide a multilayer reflective film-coated substrate having a protective film including a first layer for protecting the multilayer reflective film from oxidation and a second layer having high resistance to an etching gas used in etching the absorber film, wherein the multilayer reflective film-coated substrate has improved adhesion between the first layer and the second layer, maintains high reflectivity for EUV light, and can maintain high etching resistance of the protective film.

[0015] Another object of the present invention is to provide a reflective mask blank or a reflective mask that can improve the adhesion between the first and second layers of the protective film, and that can maintain high reflectivity to EUV light and high etching resistance of the protective film by improving the adhesion between the first and second layers.

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

[0017] (Configuration 1) Configuration 1 is 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, wherein the protective film includes a first layer and a second layer, and the first layer is disposed between the second layer and the multilayer reflective film, the protective film includes at least one metal element Em and at least one additional element Ea, and the content of the metal element Em in the second layer is higher than the content of the metal element Em in the first layer, the metal element Em is an element having a Fermi level of −4.7 eV or less, and the additional element Ea is an element having a Fermi level of more than −4.7 eV, and the position x at which the component dominance of the second layer switches to the component dominance of the first layer in a content distribution of a component included in the protective film with respect to a position x in a thickness direction of the protective film is defined as an inflection point x. １ When the content of the metal element Em is M and the content of the additional element Ea is A, the inflection point x １ The multilayer reflective film-coated substrate is characterized in that the ratio A / M is 0.020 or more.

[0018] (Configuration 2) Configuration 2 is the multilayer reflective film-coated substrate of configuration 1, in which the metal element Em is one or more elements selected from ruthenium (Ru), rhodium (Rh), and iridium (Ir).

[0019] (Configuration 3) Configuration 3 is the multilayer reflective film-coated substrate of Configuration 1 or 2, in which the additional element Ea is one or more elements selected from Tl, Hf, Ti, Zr, Y, Mn, In, Ga, Cd, Bi, Ta, Pb, Ag, Al, V, Nb, Sn, Zn, Hg, Cr, Fe, Sb, W, Mo, and Cu.

[0020] (Configuration 4) Configuration 4 is the inflection point x １ 4. The multilayer reflective film coated substrate according to any one of configurations 1 to 3, wherein the content A of the additional element Ea in the above formula (1) is 1 atomic % or more and 15 atomic % or less.

[0021] (Configuration 5) Configuration 5 is the inflection point x １ 5. The multilayer reflective film coated substrate according to any one of configurations 1 to 4, wherein the content M of the metal element Em in the matrix is ​​5 atomic % or more and 80 atomic % or less.

[0022] (Configuration 6) Configuration 6 is the inflection point x １ 6. The multilayer reflective film coated substrate according to any one of configurations 1 to 5, wherein the ratio A / M is less than 0.17.

[0023] (Configuration 7) Configuration 7 is the first layer containing silicon (Si) and at least one selected from nitrogen (N) and oxygen (O), and the inflection point x １ 7. The multilayer reflective film-coated substrate according to any one of configurations 1 to 6, wherein the total content of nitrogen (N) and oxygen (O) in the multilayer reflective film is 2 atomic % or more.

[0024] (Configuration 8) Configuration 8 is the inflection point x １ 8. The multilayer reflective film-coated substrate of claim 7, wherein the total content of nitrogen (N) and oxygen (O) in the above is 35 atomic % or less.

[0025] (Configuration 9) Configuration 9 is a reflective mask blank characterized by comprising an absorber film on the protective film of the multilayer reflective film coated substrate of any one of configurations 1 to 8.

[0026] (Configuration 10) Configuration 10 is a reflective mask characterized by comprising an absorber pattern obtained by patterning the absorber film of the reflective mask blank of configuration 9.

[0027] (Configuration 11) Configuration 11 is a method for manufacturing a semiconductor device, characterized by comprising a step of performing a lithography process using an exposure apparatus with the reflective mask of configuration 10 to form a transfer pattern on a transfer target.

[0028] According to the present invention, in a multilayer reflective film-coated substrate having a protective film including a first layer for protecting the multilayer reflective film from oxidation and a second layer having high resistance to an etching gas used in etching the absorber film, it is possible to improve adhesion between the first layer and the second layer. Also, according to the present invention, in a multilayer reflective film-coated substrate having a protective film including a first layer for protecting the multilayer reflective film from oxidation and a second layer having high resistance to an etching gas used in etching the absorber film, it is possible to obtain a multilayer reflective film-coated substrate that has improved adhesion between the first layer and the second layer, maintains high reflectivity for EUV light, and maintains high etching resistance of the protective film.

[0029] Furthermore, according to the present invention, it is possible to obtain a reflective mask blank or a reflective mask in which the adhesion between the first and second layers of the protective film can be improved. Furthermore, it is possible to obtain a reflective mask blank or a reflective mask in which the adhesion between the first and second layers is improved, high reflectivity to EUV light is maintained, and high etching resistance of the protective film is maintained.

[0030] FIG. 1 is a cross-sectional view schematically showing an example of a multilayer reflective film coated substrate of the present embodiment. FIG. 2 is a cross-sectional view schematically showing an example of a reflective mask blank of the present embodiment. FIG. 3 is a cross-sectional view schematically showing another example of a 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. １ 1 is a diagram for explaining the relationship between the total content (atomic %) of nitrogen (N) and oxygen (O) (X axis) and the ratio A / M (Y axis) of the content M of the metal element Em to the content A of the additional element Ea in the protective film 3 of the third embodiment. １ Distribution ratio y(x １ ) (X-axis), and the inflection point x １ Distribution ratio y(x １ ) slope y'(x １ ) (Y-axis) is a diagram for explaining the relationship.

[0031] 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.

[0032] Fig. 1 is a cross-sectional schematic diagram showing an example of a multilayer reflective film-coated substrate 90 of this embodiment. The multilayer reflective film-coated substrate 90 shown in Fig. 1 includes a multilayer reflective film 2 and a protective film 3 on a substrate 1. The protective film 3 includes a first layer 32 and a second layer 34, in this order, on the multilayer reflective film 2. The multilayer reflective film-coated substrate 90 may further include other thin films, such as a back surface conductive film 5.

[0033] Fig. 2 is a cross-sectional schematic diagram showing an example of a reflective mask blank 100 of this embodiment. The reflective mask blank 100 shown in Fig. 2 comprises a multilayer reflective film 2, a protective film 3, and an absorber film 4 on a substrate 1. The reflective mask blank 100 may have a back surface conductive film 5. The multilayer reflective film-coated substrate 90 may further have other thin films such as a resist film 11.

[0034] Fig. 3 is a cross-sectional schematic diagram showing another example of a reflective mask blank 100. The reflective mask blank 100 shown in Fig. 3 further comprises an etching mask film 6 on an absorber film 4 in addition to the configuration shown in Fig. 2. Note that the reflective mask blank 100 may further comprise other thin films such as a resist film 11.

[0035] In this specification, "thin film B is disposed (formed) on thin film A (or substrate)" not only means that thin film B is disposed (formed) in contact with the surface of thin film A (or substrate), but also means that another thin film C is present between thin film A (or substrate) 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)" means that thin film A (or substrate) 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, etc.

[0036] <Substrate 90 with Multilayer Reflective Film> This embodiment is a substrate 90 with a multilayer reflective film, which includes a substrate 1, a multilayer reflective film 2 provided on the substrate 1, and a protective film 3 provided on the multilayer reflective film 2. The substrate 90 with a multilayer reflective film of this embodiment will be specifically described.

[0037] <<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.

[0038] 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 second main surface (rear surface) opposite the side on which the transfer pattern is formed is the surface fixed to the exposure apparatus by an electrostatic chuck. In a 142 mm × 142 mm area of ​​the rear surface, the flatness is 0.1 μm or less, more preferably 0.05 μm or less, and particularly preferably 0.03 μm or less. In this specification, flatness is a value representing the warpage (deformation 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.

[0039] 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.

[0040] 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.

[0041] <<Multilayer reflective film 2>>

[0042] The multilayer reflective film coated substrate 90 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 elements with different refractive indices as main components are periodically stacked.

[0043] 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 40 to 60 cycles.

[0044] 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 from the substrate 1 side 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 from the substrate 1 side are stacked. The topmost layer of the multilayer reflective film 2, i.e., the surface layer of the multilayer reflective film 2 opposite the substrate 1 side, is preferably 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 from the substrate 1 side are stacked, the topmost layer is the low-refractive-index layer. In this case, if the low-refractive-index layer constitutes the topmost surface of the multilayer reflective film 2, it will be easily oxidized, thereby reducing 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 topmost low-refractive-index layer. The high-refractive index layer formed on the uppermost low-refractive index layer can be the first layer 32 of the protective film 3 described below. On the other hand, in the above-mentioned multilayer film, if a low-refractive index layer / high-refractive index layer stack structure in which a low-refractive index layer and a high-refractive index layer are stacked in this order from the substrate 1 side is stacked multiple times, the uppermost layer will be the high-refractive index layer. Therefore, in this case, there is no need to form an additional high-refractive index layer. In this case, the uppermost high-refractive index layer can also serve as the first layer 32 of the protective film 3 described below.

[0045] 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 reflectivity for EUV light can be obtained. The low-refractive index layer can be a metal element selected from molybdenum (Mo), ruthenium (Ru), rhodium (Rh), and platinum (Pt), or an alloy thereof. These metal elements or alloys may also be doped with boron (B), carbon (C), nitrogen (N), oxygen (O), and / or hydrogen (H). In the multilayer reflective film-coated substrate 90 of this embodiment, the low-refractive index layer is preferably a molybdenum (Mo) layer, and the high-refractive index layer is preferably a silicon (Si) layer. For example, a Mo / Si periodic stacked film in which Mo layers and Si layers are alternately stacked for approximately 40 to 60 periods can be preferably used as the multilayer reflective film 2 for reflecting EUV light with a wavelength of 13 nm to 14 nm (e.g., 13.5 nm). Furthermore, in the multilayer reflective film-coated substrate 90 of this embodiment, the low refractive index layers are preferably ruthenium (Ru) layers, and the high refractive index layers are preferably silicon (Si) layers. For example, a Ru / Si periodic stacked film in which Ru layers and Si layers are alternately stacked for approximately 30 to 40 periods can be preferably used as the multilayer reflective film 2 for reflecting EUV light with a wavelength of 13 nm to 14 nm (e.g., 13.5 nm).

[0046] The reflectance of the multilayer reflective film 2 alone is usually 65% ​​or more, with the upper limit usually being 73%. The film thickness and period of each constituent layer of the multilayer reflective film 2 can be appropriately selected depending on the exposure wavelength. Specifically, the film 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 has a plurality of high refractive index layers and a plurality of low refractive index layers, but the film thicknesses of the high refractive index layers and the low refractive index layers do not necessarily have to be the same.

[0047] Methods for forming the multilayer reflective film 2 are known 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, a Si film having a thickness of about 4 nm is first deposited on the substrate 1 by ion beam sputtering using a Si target, and then a Mo film having a thickness of about 3 nm is deposited using a Mo target. This constitutes one period, and 40 to 60 periods are stacked to form the multilayer reflective film 2 (the outermost layer is a Si film). Note that, although 60 periods requires more steps than 40 periods, the reflectivity for EUV light can be increased.

[0048] <<Protective Film 3>> As shown in FIG. 1 , the multilayer reflective film-coated substrate 90 of this embodiment has a predetermined protective film 3 on the multilayer reflective film 2. When manufacturing the reflective mask 200, the absorber film 4 is etched to form an absorber pattern 4a. The protective film 3 has high etching resistance, and therefore can suppress damage to the surface of the multilayer reflective film 2 when etching the absorber film 4. Therefore, by having the predetermined protective film 3 on the multilayer reflective film 2, damage to the surface of the multilayer reflective film 2 can be suppressed when manufacturing the reflective mask 200 using the multilayer reflective film-coated substrate 90. As a result, the resulting reflective mask 200 has good reflectance characteristics for EUV light.

[0049] In this specification, the predetermined protective film 3 that can be used for the multilayer reflective film coated substrate 90 of this embodiment may be referred to as the "protective film 3 of this embodiment."

[0050] The protective film 3 of this embodiment includes a first layer 32 and a second layer 34. The first layer 32 is disposed between the second layer 34 and the multilayer reflective film 2. The first layer 32 is a thin film that functions to protect the multilayer reflective film 2 from oxidation. In this specification, the first layer 32 is a part of the protective film 3. The first layer 32 can also serve as the uppermost layer of the multilayer reflective film 2. The second layer 34 is a thin film that functions to have high resistance to the etching gas used to etch the absorber film 4. The second layer 34 needs to be a thin film that has high reflectivity for EUV light and high etching resistance to the etching gas.

[0051] When the protective film 3 has a structure in which the second layer 34 is disposed on the first layer 32, a phenomenon may occur in which the reflectivity of the multilayer reflective film-coated substrate 90 for EUV light decreases due to heat treatment or the like in the manufacturing process of the reflective mask. This is thought to be due to the diffusion of a predetermined element (an element that exhibits the function of the first layer 32) in the first layer 32 into the second layer 34. In order to prevent a decrease in the reflectivity of the multilayer reflective film-coated substrate 90, it is necessary to prevent the predetermined element in the first layer 32 from diffusing into the second layer 34. In order to prevent the predetermined element in the first layer 32 from diffusing into the second layer 34, it is considered to nitriding and / or oxidizing the surface of the first layer 32 (the interface between the first layer 32 and the second layer 34). On the other hand, it has been found that nitriding and / or oxidizing the surface of the first layer 32 (the interface with the second layer 34) causes a problem of reduced adhesion between the first layer 32 and the second layer 34. If the adhesion between the first layer 32 and the second layer 34 decreases, there is a risk of film peeling defects occurring.

[0052] The protective film 3 of this embodiment contains at least one metal element Em and at least one additive element Ea. That is, the first layer 32 and the second layer 34 constituting the protective film 3 can contain the metal element Em and / or the additive element Ea. By containing the metal element Em, the protective film 3 of this embodiment can have high etching resistance against the etching gas of the absorber film 4. Furthermore, by containing the additive element Ea, the protective film 3 of this embodiment can improve the adhesion between the first layer 32 and the second layer 34. Therefore, the protective film 3 of this embodiment can suppress the occurrence of film peeling defects. That is, the protective film 3 of this embodiment can provide a multilayer reflective film-coated substrate 90 that can improve the adhesion between the first layer 32 and the second layer 34 while maintaining the high etching resistance of the protective film 3.

[0053] <<<Metal Element Em>>> The protective film 3 contains at least one metal element Em. The metal element Em is an element having a Fermi level of −4.7 eV or less. In this specification, the content (atomic %) of the metal element Em is indicated by the symbol “M.” In addition, in this specification, the metal element Em is also referred to as the Em element.

[0054] The metal element Em is an element (metal element) that functions as the protective film 3. The metal element Em has a Fermi level of −4.7 eV or less, and therefore has low reactivity with chlorine (Cl)-based gases, bromine (Br)-based gases, and fluorine (F)-based gases, as well as gases containing nitrogen and / or oxygen as constituent elements that are used in reactive sputtering. Therefore, when the metal element Em is used as the material for the protective film 3, the material is less likely to deteriorate, and the function of the protective film 3 is less likely to be reduced. Therefore, when the metal element Em is selected according to the material of the absorber film 4 disposed on the protective film 3 and the metal element Em is used as the material for the protective film 3, a protective film 3 with high etching resistance can be obtained.

[0055] In this specification, the Fermi level of a certain element refers to the energy value of the Fermi level of a pure substance of the element when the vacuum level is taken as the origin (zero). In this specification, the Fermi level of a metallic material can be the energy obtained by making the value of the work function negative. For example, when the metallic element Em is Ru, the work function of a pure substance of the Ru element (pure substance of Ru metal) is 4.7 eV, and therefore, in this specification, the Fermi level of Ru is −4.7 eV. The same applies to the additive element Ea described below.

[0056] The metal element Em can be an element having a Fermi level equal to or lower than that of Ru. Ru is known to be a suitable element for forming the protective film 3. Therefore, by using an element (metal element) having a Fermi level equal to or lower than that of Ru (a Fermi level with a large negative value), a thin film having high etching resistance can be obtained.

[0057] Examples of elements having a Fermi level lower than that of Ru include Ru, Tc, Os, Co, Re, Rh, Pd, Au, Ni, Ir, and Pt. At least one selected from these elements can be used as the metal element Em.

[0058] The metal element Em contained in the protective film 3 of this embodiment is preferably one or more elements selected from ruthenium (Ru), rhodium (Rh), and iridium (Ir). The metal element Em contained in the protective film 3 of this embodiment can consist of only one or more elements selected from ruthenium (Ru), rhodium (Rh), and iridium (Ir). By using these elements, it is possible to more reliably obtain a protective film 3 that has high etching resistance while maintaining high reflectivity.

[0059] Specifically, when the protective film 3 contains Rh or Ir as the metal element Em, it is possible to improve the etching resistance of the protective film 3. Furthermore, when the protective film 3 contains Ru as the metal element Em, it is possible to appropriately adjust the optical properties of the protective film 3.

[0060] <<<Additive Element Ea>>> The protective film 3 contains at least one additional element Ea. The additional element Ea is an element having a Fermi level of greater than −4.7 eV. In this specification, the content (atomic %) of the additional element Ea is indicated by the symbol “A.” In addition, in this specification, the additional element Ea is also referred to as the Ea element.

[0061] The protective film 3 contains the additive element Ea, which can improve the adhesion between the first layer 32 and the second layer 34 that constitute the protective film 3. The additive element Ea is an element that has a Fermi level of more than −4.7 eV and is therefore highly reactive with other elements. Therefore, the protective film 3 contains the additive element Ea, which can contribute to improving the adhesion between the first layer 32 and the second layer 34.

[0062] The additive element Ea can be an element having a Fermi level equal to or higher than that of Cu. Cu can be used as an element that can improve the adhesion between two types of thin films. Therefore, using an element having a Fermi level equal to or higher than that of Cu (a Fermi level with a small negative value) can contribute to improving the adhesion between the first layer 32 and the second layer 34.

[0063] The additive element Ea contained in the protective film 3 of this embodiment is preferably one or more elements selected from Tl, Hf, Ti, Zr, Y, Mn, In, Ga, Cd, Bi, Ta, Pb, Ag, Al, V, Nb, Sn, Zn, Hg, Cr, Fe, Sb, W, Mo, and Cu. The additive element Ea contained in the protective film 3 of this embodiment may consist solely of one or more elements selected from Tl, Hf, Ti, Zr, Y, Mn, In, Ga, Cd, Bi, Ta, Pb, Ag, Al, V, Nb, Sn, Zn, Hg, Cr, Fe, Sb, W, Mo, and Cu. The use of these elements can more reliably contribute to improving the adhesion between the first layer 32 and the second layer 34.

[0064] The additive element Ea contained in the protective film 3 of this embodiment is more preferably at least one selected from Ti, Zr, Ta, Nb, and Cr. Furthermore, it is even more preferable to use at least one selected from Ta, Nb, and Cr as the additive element Ea contained in the protective film 3 of this embodiment. By using these elements, it is possible to improve the adhesion between the first layer 32 and the second layer 34 and also improve cleaning resistance.

[0065] When nitrogen is contained near the surface of the first layer 32 (the interface between the first layer 32 and the second layer 34), it is more preferable to use Cr as the additional element Ea contained in the protective film 3 of this embodiment. This is because Cr, when nitrided, reduces the extinction coefficient, reduces the absorption of EUV light, and can contribute to improving the reflectance. On the other hand, Hf, Ti, Zr, Y, V, and Nb, when nitrided, tend to increase the extinction coefficient, strengthen the absorption of EUV light, and reduce the reflectance.

[0066] When oxygen is contained near the surface of the first layer 32 (the interface between the first layer 32 and the second layer 34), it is preferable to use at least one selected from Hf, V, and Cr as the additional element Ea contained in the protective film 3 of this embodiment. This is because Hf, V, and Cr decrease the extinction coefficient when oxidized, which can reduce the absorption of EUV light and contribute to improving the reflectance. On the other hand, Ti, Zr, Y, and Nb increase the extinction coefficient when nitriding, which tends to enhance the absorption of EUV light and reduce the reflectance.

[0067] The metal element Em can be contained in either the first layer 32 or the second layer 34. That is, as long as the metal element Em can be present at the interface between the first layer 32 and the second layer 34, the metal element Em can be added when the first layer 32 is formed, or the metal element Em can be added when the second layer 34 is formed. Furthermore, the metal element Em can be added when both the first layer 32 and the second layer 34 are formed.

[0068] <<<First Layer 32>>> The first layer 32 of the protective film 3 of this embodiment can be disposed on and in contact with the multilayer reflective film 2. The first layer 32 is a thin film that is part of the protective film 3 and protects the multilayer reflective film 2 from oxidation.

[0069] The material of the first layer 32 is not particularly limited as long as it can protect the multilayer reflective film 2 from oxidation. Examples of the material of the first layer 32 include materials containing silicon (Si) (e.g., Si, SiN, SiO, SiON, and SiC) and materials containing boron (B) and carbon (C) (e.g., B ４ The first layer 32 may be, for example, a thin film formed under conditions where it is made of only silicon (Si), a thin film formed under conditions where it is made of only SiN, or B ４ It is possible to form a thin film under conditions in which the multilayer reflective film 2 is made of only C. When the uppermost layer of the multilayer reflective film 2 is a high refractive index layer, the uppermost high refractive index layer can also serve as the first layer 32 of the protective film 3.

[0070] In the present specification, the first layer 32 may be a thin film formed under conditions such that it is made of only silicon (Si), a thin film formed under conditions such that it is made of only SiN, or a thin film formed under conditions such that it is made of only SiN. ４ The term "thin film formed under conditions for forming a thin film consisting of only silicon (Si)" refers to a thin film formed under conditions for forming a thin film consisting of only SiN, or a thin film formed under conditions for forming a thin film consisting of only B. ４This refers to a thin film formed under conditions that result in the formation of a thin film consisting only of C. After the formation of the first layer 32 (and the second layer 34 described below), elements other than those constituting the first layer 32 may diffuse from the nearby multilayer reflective coating 2 and second layer 34 into the first layer 32. In this case, for example, the first layer 32, which is a "thin film formed under conditions that result in the formation of only silicon (Si)," will contain elements other than silicon (Si) that diffuse from other layers after the formation of the first layer 32. In this way, due to the diffusion of elements from other thin films from thin films near the first layer 32 into the first layer 32, a thin film formed under conditions that result in the formation of only a specific element will generally contain elements other than the specific element. Therefore, a thin film formed under conditions that result in the formation of only silicon (Si) can be a thin film containing Si. Furthermore, a thin film formed under conditions that result in the formation of only SiN can be a thin film containing SiN. Furthermore, B ４ The thin film formed under the condition that it consists only of C is B ４ It may be a thin film containing C.

[0071] The first layer 32 of the protective film 3 of this embodiment can be formed by various known methods, such as ion beam sputtering, sputtering, reactive sputtering, chemical vapor deposition (CVD), and vacuum deposition.

[0072] When the first layer 32 is a thin film formed under conditions that allow the first layer 32 to consist only of silicon (Si), the first layer 32 can be formed under conditions that allow the first layer 32 to consist only of silicon (Si). For example, the first layer 32 can be formed by ion beam sputtering using a Si target.

[0073] When the first layer 32 is a thin film formed under conditions in which it consists only of SiN, for example, the first layer 32 can be formed by DC magnetron sputtering (reactive sputtering) using a Si target in a nitrogen gas atmosphere.

[0074] The first layer 32 is B ４In the case of a thin film formed under conditions in which the first layer 32 is composed only of C, for example, the first layer 32 can be formed by ion beam sputtering using a target containing B and C in a predetermined composition.

[0075] The first layer 32 may be a thin film formed under conditions that include the additional element Ea. The first layer 32 may be made of Si, SiC, and / or B. ４ The first layer 32 may be a thin film containing C and the additional element Ea. The first layer 32 may contain the additional element Ea. By containing the additional element Ea in the first layer 32, the additional element Ea can be present at the interface between the first layer 32 and the second layer 34. As a result, the adhesion between the first layer 32 and the second layer 34 can be improved.

[0076] The first layer 32 is made of Si, SiC and / or B. ４ The thin film containing C and the additional element Ea may further contain at least one selected from nitrogen (N) and oxygen (O). The first layer 32 preferably contains nitrogen (N) and / or oxygen (O) near the interface with the second layer 34. When the first layer 32 has a high content of nitrogen (N) and / or oxygen (O), it is possible to suppress the diffusion of elements (e.g., silicon (Si)) from the first layer 32 into the second layer 34. As a result, it is possible to suppress a decrease in the reflectance of the second layer 34 due to the diffusion of elements from the first layer 32.

[0077] In order to introduce nitrogen (N) and / or oxygen (O) into the first layer 32 or the second layer 34, the first layer 32 or the second layer 34 can be formed in a nitrogen gas and / or oxygen gas atmosphere by DC magnetron sputtering (reactive sputtering). As a result, a decrease in the reflectivity of the second layer 34 due to diffusion of elements in the first layer 32 can be suppressed.

[0078] As described above, in order to prevent the elements of the first layer 32 from diffusing into the second layer 34, it is preferable to introduce nitrogen (N) and / or oxygen (O) into the interface between the first layer 32 and the second layer 34 to increase the concentration of nitrogen (N) and / or oxygen (O) at the interface between the first layer 32 and the second layer 34. However, if the concentration of nitrogen (N) and / or oxygen (O) at the interface between the first layer 32 and the second layer 34 becomes too high, the reflectivity decreases and adhesion deteriorates, so it is necessary to set the concentration to a predetermined level. This point will be discussed later.

[0079] <<<Second Layer 34>>> The second layer 34 of the protective film 3 of this embodiment is disposed on and in contact with the first layer 32. The second layer 34 can be a thin film that has the same function as the protective film 3, that is, increases the resistance of the protective film 3 to etching gases and cleaning.

[0080] The second layer 34 contains the above-mentioned metal element Em. The second layer 34 can be a thin film formed under conditions that allow the second layer 34 to contain the metal element Em. The content of the metal element Em in the second layer 34 is greater than the content of the metal element Em in the first layer 32. This is because the second layer 34 is required to be a thin film having high etching resistance.

[0081] The metal element Em contained in the second layer 34 is preferably one or more elements selected from ruthenium (Ru), rhodium (Rh), and iridium (Ir). By using these elements, the second layer 34 can be obtained with high etching resistance while maintaining high reflectivity.

[0082] The second layer 34 can be a thin film formed under conditions that allow the second layer 34 to contain the additional element Ea. The second layer 34 can contain the additional element Ea. By including the additional element Ea in the second layer 34, the additional element Ea can be present at the interface between the first layer 32 and the second layer 34. As a result, the adhesion between the first layer 32 and the second layer 34 can be improved.

[0083] The second layer 34 can be a thin film formed under conditions that allow the second layer 34 to contain the metal element Em and the additive element Ea. The second layer 34 can contain both the metal element Em and the additive element Ea. By including the metal element Em in the second layer 34, the second layer 34 can have high etching resistance. Furthermore, by including the additive element Ea in the second layer 34, improved adhesion between the first layer 32 and the second layer 34 can be more reliably achieved.

[0084] In the second layer 34 herein, the terms "a thin film formed under conditions to contain the metal element Em" or "a thin film formed under conditions to contain the additive element Ea" refer to a thin film formed under conditions to form a thin film containing the metal element Em or a thin film formed under conditions to form a thin film containing the additive element Ea during the formation of the first layer 32. After the formation of the second layer 34, elements other than those constituting the second layer 34 may diffuse from the first layer 32 to the second layer 34. In such a case, for example, the "thin film formed under conditions to contain the metal element Em" will contain an element (e.g., silicon (Si)) that diffuses from the first layer 32 to the second layer 34 after the formation of the first layer 32. In this way, a thin film formed under conditions to contain a predetermined element generally contains elements other than the predetermined element due to the diffusion of elements from other thin films from a thin film near the second layer 34 to the second layer 34.

[0085] The content of the metal element Em in the second layer 34 is preferably 40 to 95 atomic %, and more preferably 50 to 90 atomic %. The content of the additional element Ea in the second layer 34 is preferably 1 to 10 atomic %, and more preferably 2 to 8 atomic %. The content here indicates the content (atomic %) at the starting point (x=0) of the curve fitting described below. Note that the above content is the content at the position where the total content (atomic %) of the Em element and the Ea element is at its maximum, and therefore can also be said to be the central composition of the second layer 34.

[0086] The second layer 34 may further contain at least one selected from nitrogen (N) and oxygen (O). The second layer 34 may be a thin film formed under conditions such that it contains the metal element Em, the additional element Ea, and at least one selected from nitrogen (N) and oxygen (O). The second layer 34 may be a thin film formed under conditions such that it contains only at least one selected from the metal element Em, the additional element Ea, nitrogen (N), and oxygen (O).

[0087] In order for the second layer 34 to have high reflectivity for EUV light, the nitrogen (N) and / or oxygen (O) content of the second layer 34 is preferably low. On the other hand, if the nitrogen (N) and / or oxygen (O) content is high, the elements of the first layer 32 (e.g., silicon (Si)) can be suppressed from diffusing into the second layer 34. By suppressing the diffusion of the elements of the first layer 32 (e.g., silicon (Si)) into the second layer 34, it is possible to suppress a decrease in the effective film thickness of the second layer 34, which functions as the protective film 3. In consideration of the above, it is preferable that the second layer 34 contains nitrogen (N) and / or oxygen (O) near the interface with the first layer 32. This can suppress a decrease in the reflectivity of the multilayer reflective coating 2 for EUV light, which would be caused by the diffusion of the elements of the first layer 32 into the second layer 34.

[0088] The second layer 34 of the protective film 3 of this embodiment can be formed by various known methods, such as ion beam sputtering, sputtering, reactive sputtering, chemical vapor deposition (CVD), and vacuum deposition. The second layer 34 of the protective film 3 of this embodiment is preferably formed by magnetron sputtering (reactive sputtering) in a nitrogen gas atmosphere. The target may be, for example, a single metal target or an alloy target of the metal components (metal elements, e.g., metal element Em and / or additive element Ea) contained in the second layer 34. When the second layer 34 is formed by reactive sputtering, the second layer 34 can be formed continuously in a nitrogen gas atmosphere after the formation of the first layer 32.

[0089] When the second layer 34 is a thin film formed under conditions that include the metal element Em, the additional element Ea, and nitrogen (N) and / or oxygen (O), the second layer 34 can be formed, for example, by DC magnetron sputtering (reactive sputtering) in a nitrogen (N) gas and / or oxygen (O) gas atmosphere using an alloy target of at least one metal element Em and at least one additional element Ea.

[0090] When depositing the second layer 34, the second layer 34 can be deposited with a predetermined composition distribution by changing deposition conditions such as the nitrogen gas flow rate (pressure) and / or applied power. However, if appropriate deposition conditions are selected, the second layer 34 can be deposited with a predetermined composition distribution due to the diffusion of elements within the second layer 34, even when the deposition conditions are kept constant. For example, when obtaining a second layer 34 containing silicon (Si), even if the second layer 34 is deposited under conditions that do not include silicon (Si), the second layer 34 can be obtained after deposition due to the diffusion of silicon (Si) from the first layer 32.

[0091] It is preferable to deposit the second layer 34 continuously after the deposition of the first layer 32 without removing the layer from the deposition apparatus to the atmosphere. If the layer 32 is removed from the deposition apparatus to the atmosphere after the deposition of the first layer 32, the surface of the first layer 32 may be excessively oxidized or contaminated with unexpected elements. Furthermore, covering the surface of the first layer 32 with a nitride film rather than an oxide film tends to improve adhesion between the first layer 32 and the second layer 34 and increase reflectivity. Therefore, it is preferable to cover the surface of the first layer 32 with a nitride film rather than an oxide film. Therefore, in order to appropriately control the oxygen concentration at the interface between the first layer 32 and the second layer 34, it is preferable to deposit the first layer 32 and the second layer 34 continuously without removing the layer from the deposition apparatus to the atmosphere.

[0092] <<<Content Distribution of Components in the First Layer 32 and the Second Layer 34>>> The protective film 3 of this embodiment includes a first layer 32 and a second layer 34. The first layer 32 is formed on the multilayer reflective film 2, and the second layer 34 is formed on the first layer 32. The second layer 34 can be formed so as to be in contact with the first layer 32.

[0093] As described above, elements contained in the first layer 32 typically diffuse into the second layer 34. Elements contained in the second layer 34 typically diffuse into the first layer 32. In this way, the elements contained in the first layer 32 and the second layer 34 typically interdiffuse. As a result of studying the interdiffusion of elements contained in the first layer 32 and the second layer 34, the present inventors found that in a region where the elements (components) of the first layer 32 and the second layer 34 interdiffuse, a predetermined content distribution of components contained in the protective film 3 with respect to the position x in the film thickness direction is related to the adhesion between the first layer 32 and the second layer 34, and arrived at the present invention.

[0094] Specifically, the predetermined content distribution of the components in the protective film 3 of this embodiment is defined as the inflection point x at which the component of the second layer 34 switches from being dominant to the component of the first layer 32 when the thickness direction (depth direction) of the protective film 3 is defined as the x axis and the position in the thickness direction (depth direction) of the protective film 3 is defined as the x axis. １ When the content of the metal element Em is M and the content of the additive element Ea is A, the inflection point x １ In this specification, the x-axis, which is the thickness direction (depth direction) of the protective film 3, can be defined as the direction in which the value of x increases from the surface of the protective film 3 where the absorber film is formed toward the interface between the protective film 3 and the multilayer reflective film.

[0095] The predetermined content distribution of the components contained in the protective film 3 will be described below.

[0096] The content distribution of components contained in the protective film 3 (the first layer 32 and the second layer 34) with respect to the position x in the thickness direction of the protective film 3 of this embodiment can be measured by, for example, energy dispersive X-ray spectroscopy (EDX) using a scanning transmission electron microscope (STEM). The content distribution can also be measured using other analytical methods, such as X-ray photoelectron spectroscopy (XPS). The content distribution of each component can be obtained by identifying the components (elements) contained in the first layer 32 and the second layer 34 and measuring the content of each component with respect to the position x in the thickness direction of the protective film 3. In the measurement by the EDX method or the XPS method, the composition of each layer may be identified by measuring the state of a reflective mask blank having the absorber film 4 or the absorber film 4 and the etching mask film 6 on the protective film 3, or the state of a reflective mask after patterning the absorber film 4.

[0097] Next, the following y(x) for the position x is calculated based on the measured values ​​of the content of each component for the position x in the thickness direction of the protective film 3. In this specification, y(x) may be simply referred to as the "distribution ratio."

[0098] y(x)=(total content of components in the first layer 32 at position x) / (total content of components in the first layer 32 and the second layer 34 at position x)

[0099] For example, if the first layer 32 is a thin film formed under conditions containing silicon (Si), nitrogen (N), and oxygen (O), and the second layer 34 is a thin film formed under conditions containing Ru (metal element Em), Rh (metal element Em), Cr (additive element Ea), nitrogen (N), and oxygen (O), the distribution ratio y(x) will be as follows: Nitrogen (N) and oxygen (O) are contained in both the first layer 32 and the second layer 34, but they do not need to be added up twice in the denominator of the following formula.

[0100] y(x) = (total content of Si content, N content, and O content at position x) / (total content of Si content, N content, O content, Ru content, Rh content, and Cr content at position x)

[0101] In the example of the distribution ratio y(x) described above, the first layer 32 is a thin film formed under conditions that include Si, but is not a thin film formed under conditions that include Ru, Rh, and Cr. Therefore, Si is selected as the component of the first layer 32, and Ru, Rh, and Cr are not selected. Similarly, the second layer 34 is a thin film formed under conditions that include Ru, Rh, and Cr, but is not a thin film formed under conditions that include Si. Therefore, Ru, Rh, and Cr are selected as the components of the second layer 34, and Si is not selected. Furthermore, nitrogen (N) and oxygen (O), which are gases at room temperature, may be contained in the first layer 32 and the second layer 34. Therefore, even if the first layer 32 is a thin film formed under conditions that include only silicon (Si), the first layer 32 may contain nitrogen (N) and / or oxygen (O) as its components. The distribution ratio y(x) can be determined not only based on the film formation conditions but also in consideration of the content distribution obtained as a result of measurement.

[0102] In particular, when quantifying elements by energy dispersive X-ray spectroscopy (EDX) using a scanning transmission electron microscope (STEM), it is necessary to process the analytical sample into a rectangular shape using a focused ion beam (FIB) or the like. In this process, a conductive protective film such as carbon (C) and / or platinum (Pt) is formed on the sample surface to prevent it from being damaged by the ion beam. During such pretreatment of the analytical sample, carbon (C) may re-adhere to the processed cross-section of the sample and be included in the quantitative value as part of the constituent components of the analytical sample. Therefore, carbon (C) can be excluded from the components of the first layer 32 and the second layer 34 used to obtain the distribution ratio y(x). However, when the first layer 32 is formed of B ４ When the carbon (C) content distribution is deemed to be dominant over measurement error as a result of forming a C thin film, carbon (C) can be included as a component of the first layer 32.

[0103] Next, the inflection point x is the position x at which the component dominance of the second layer 34 switches to the component dominance of the first layer 32. １ Find the inflection point x １The inflection point x can be defined as the inflection point when the distribution ratio y(x) of a predetermined component is curve-fitted with a predetermined function. １ can be considered to be the position of the interface between the first layer 32 and the second layer 34. As described above, since the elements (components) of the first layer 32 and the second layer 34 usually diffuse into each other, it is difficult to identify the interface between the first layer 32 and the second layer 34. However, the inflection point x １ By determining the inflection point x, the interface between the first layer 32 and the second layer 34 can be identified. １ The position of the inflection point x may be referred to as the interface between the first layer 32 and the second layer 34. １ can be found as follows:

[0104] First, the range of x is determined for curve fitting a predetermined function to the distribution ratio y(x) of a predetermined component with respect to the position x in the film thickness direction of the protective film 3. The range of x for curve fitting the distribution ratio y(x) can be determined as follows. Note that, hereinafter, the curve-fitted function will also be referred to as the distribution ratio y(x).

[0105] First, a function for curve fitting the distribution ratio y(x) is selected.

[0106] A sigmoid function can be used as a function for curve fitting the distribution ratio y(x). Sigmoid functions are generally used to approximate a sigmoid-shaped profile. As the sigmoid function, a cubic or higher order function, an error function, an exponential function, a sine function, or the like can be used.

[0107] As a function for curve fitting the distribution ratio y(x), for example, a quartic function shown in formula (1) can be used. In formula (1), a, b, c, d, and e are constants. y(x)=ax ４ +bx ３ +cx ２ +dx+e...(1)

[0108] Next, the range of x (start and end points of x) for curve fitting the distribution ratio y(x) with a predetermined function is determined. When curve fitting the distribution ratio y(x), the start point of the curve fitting (the origin of the position x in the film thickness direction) is set to the position of x = 0 (origin), and the end point of the curve fitting is set to the position of x = D. The position (depth) of x = D in the protective film 3 is a position (depth) closer to the interface between the protective film 3 and the multilayer reflective film than the position (depth) of x = 0. The start point (x = 0) in the protective film 3 can be set to the position (depth) where the total content (atomic %) of the Em element and the Ea element is maximum among the contents of each component. Furthermore, the position of x = D in the protective film 3 (end point of the fitting range) is set to the coefficient of determination R of the curve fitting with the predetermined function in the range of x where the total content (atomic %) of the Em element and the Ea element decreases from the maximum value to be 5 atomic % or more and 20 atomic % or less. ２ becomes a maximum value in the range of x. The range of x from x=0 to x=D is considered to include the interface between the first layer 32 and the second layer 34. Note that curve fitting techniques are well known.

[0109] Next, a predetermined function obtained by curve fitting the distribution ratio y(x) is differentiated twice to obtain the second derivative y''(x). １ is the inflection point x １ is.

[0110] If the function to be curve-fitted is a quartic function, the inflection point x １ The second derivative y''(x) obtained by second differentiation to obtain the second derivative y''(x) can be expressed as the following equation (2): y''(x)=12ax ２ +6bx+2c...(2)

[0111] Inflection point x of distribution ratio y(x) １ To find the solution for y''(x)=0 in equation (2), we obtain equation (3). １ = [-3b ± (9b ２ -24ac) ０．５ ] / (12a)...(3)

[0112] Since y''(x) is a quadratic function, as is clear from equation (3), there are two solutions for y''(x) = 0. In this case, the distribution ratio y(x) is curve-fitted with a cubic function, and the solution that satisfies the second derivative of the quartic function y''(x) = 0, which is closer to the x value of the solution where the linear function of the second derivative obtained by differentiating the cubic function twice, is zero, is determined as the inflection point x. １ It can be said that:

[0113] The inflection point x obtained as described above １ indicates the position x (depth in the thickness direction of the protective film 3) at which the component of the second layer 34 switches to the component of the first layer 32. １ At the position of the inflection point x, when the content of the metal element Em is M (atomic %) and the content of the additive element Ea is A (atomic %), １ The ratio A / M in is 0.020 or more, and preferably 0.022 or more. When the protective film 3 contains multiple metal elements Em, the content M of the metal elements Em is the total content (atomic %) of the multiple metal elements Em. When the protective film 3 contains multiple additive elements Ea, the content A of the additive elements Ea is the total content (atomic %) of the multiple additive elements Ea.

[0114] As mentioned above, this inflection point x １ At the position of the inflection point x, when the content of the metal element Em is M (atomic %) and the content of the additive element Ea is A (atomic %), １ In this specification, the protective film 3 of this embodiment in which the ratio A / M is 0.020 or more may be referred to as a first mode of the protective film 3 of this embodiment.

[0115] inflection point x １ It can be said that the inflection point x corresponds to the interface between the first layer 32 and the second layer 34. １ When the ratio A / M is equal to or greater than the predetermined ratio, the content of the additional element Ea is equal to or greater than the predetermined content relative to the content of the metal element Em at the interface between the first layer 32 and the second layer 34. When the protective film 3 of this embodiment has such a distribution of the contents of the metal element Em and the additional element Ea, the adhesion between the first layer 32 and the second layer 34 can be improved.

[0116] The multilayer reflective film coated substrate 90 of this embodiment has an inflection point x １ is preferably less than 0.17, more preferably 0.16 or less, and even more preferably 0.12 or less. By setting the upper limit of the ratio A / M to a predetermined value, it is possible to prevent the reflectance of the multilayer reflective film-coated substrate 90 from being adversely affected by an excessively large content A of the additional element Ea.

[0117] x of the first derivative of y(x) １ The value (y'(x １ )) is the position x １ If y(x) is a quartic function, then the slope of y(x) at the position x １ The slope of y(x) in (y'(x １ )) can be expressed by the following formula (4): １ ) = 4ax １ ３ +3bx １ ２ +2cx １ + d ... (4)

[0118] Gradient y'(x １ The larger the gradient y'(x) of the distribution ratio y(x), the steeper the change in composition at the interface between the first layer 32 and the second layer 34, and the smaller the degree of diffusion of the components (elements) at the interface between the first layer 32 and the second layer 34. In the protective film 3 of this embodiment, the gradient y'(x) of the distribution ratio y(x) １ ) is preferably large.

[0119] The protective film 3 of the multilayer reflective film coated substrate 90 of this embodiment has an inflection point x １ The content A of the additional element Ea in the inflection point x is preferably 1 atomic % or more and 15 atomic % or less, and more preferably 1.5 atomic % or more and 10 atomic % or less. １ When the content A of the additional element Ea is within the predetermined range, the adhesion between the first layer 32 and the second layer 34 can be further improved.

[0120] The protective film 3 of the multilayer reflective film coated substrate 90 of this embodiment has an inflection point x １The content M of the metal element Em in the inflection point x is preferably 5 atomic % or more and 80 atomic % or less, and more preferably 10 atomic % or more and 75 atomic % or less. １ When the content M of the metal element Em is within the predetermined range, a protective film 3 having high etching resistance can be obtained.

[0121] In the protective film 3 of the multilayer reflective film coated substrate 90 of this embodiment, the first layer 32 contains silicon (Si) and at least one selected from nitrogen (N) and oxygen (O), and the inflection point x １ The total content of nitrogen (N) and oxygen (O) in the film is preferably 2 atomic % or more, and more preferably 4 atomic % or more. １ In the above, by ensuring that the nitrogen (N) and oxygen (O) contents are equal to or greater than a predetermined amount, adverse effects caused by the diffusion of elements (e.g., Si) of the components of the first layer 32 into the second layer 34 can be suppressed.

[0122] The protective film 3 of the multilayer reflective film coated substrate 90 of this embodiment has an inflection point x １ The total content of nitrogen (N) and oxygen (O) in the first layer 32 and the second layer 34 is preferably 35 atomic % or less, and more preferably 30 atomic % or less. If the content of nitrogen (N) and / or oxygen (O) at the interface between the first layer 32 and the second layer 34 is too high, film peeling may occur at the interface between the first layer 32 and the second layer 34. Therefore, the inflection point x １ The total content of nitrogen (N) and oxygen (O) in the above is preferably a predetermined amount or less.

[0123] The thickness of the first layer 32 is preferably 1.0 to 2.0 nm, more preferably 1.2 to 1.5 nm. The thickness of the second layer 34 is preferably 1.5 to 5.0 nm, more preferably 2.0 to 4.0 nm. The thicknesses of the first layer 32 and the second layer 34 are determined by the thickness of the interface between the first layer 32 and the second layer 34 at the inflection point x １ This is the film thickness when it is assumed to be located at

[0124] The total thickness of the protective film 3 including the first layer 32 and the second layer 34 (sometimes simply referred to as the "thickness of the protective film 3") is not particularly limited as long as it can function as the protective film 3. From the viewpoint of reflectivity of EUV light, the thickness of the protective film 3 is preferably 1.0 nm to 8.0 nm, and more preferably 1.5 nm to 6.0 nm.

[0125] Furthermore, the contents of the components (metal element Em, additional element Ea, etc.) contained in the first layer 32 and the second layer 34 described above can be such that a composition gradient changes continuously in the film thickness direction (depth direction) of each layer.

[0126] The multilayer reflective film-coated substrate 90 of this embodiment can be heat-treated after the protective film 3 is formed, or after the absorber film 4 is formed to obtain the reflective mask blank 100. In this heat treatment, heating can be performed at a temperature higher than the pre-bake temperature (approximately 110°C) of the resist film 11 in the manufacturing process of the reflective mask blank 100. Specifically, the temperature conditions for the heat treatment are usually 130°C or higher and 300°C or lower, and preferably 150°C or higher and 250°C or lower. The heat treatment can adjust the stress of the substrate 1 and thin films (such as the protective film 3) formed on the substrate 1. The multilayer reflective film-coated substrate 90 and the reflective mask blank 100 of this embodiment can suppress a decrease in the reflectivity of the multilayer reflective film 2 for EUV light, even when heat-treated.

[0127] The protective film 3 of this embodiment may further include layers other than the first layer 32 and the second layer 34 described above, as necessary.

[0128] In addition, by performing the above-mentioned heat treatment, it may be possible to obtain a second layer 34 with a more preferable composition by promoting the diffusion of nitrogen contained in the second layer 34 and suppressing the diffusion of Si into the second layer 34.

[0129] <<<<Second Aspect of Protective Film 3 >>> Next, a second aspect of the protective film 3 of the multilayer reflective film coated substrate 90 of this embodiment will be described.

[0130] The protective film 3 of the second aspect of this embodiment includes a first layer 32 and a second layer 34, similar to the first aspect described above. The protective film 3 of the second aspect has an inflection point x , which is the position x at which the component of the second layer 34 switches from being predominant to being predominant in the component of the first layer 32, similar to the above aspect. １ In addition, the protective film 3 of the second embodiment has an inflection point x １ The ratio A / M at the inflection point x １ The total content (atomic %) of nitrogen (N) and oxygen (O) in the protective film 3 of the second aspect of this embodiment has a specific relationship.

[0131] Specifically, the inflection point x １ In a graph in which the ratio A / M in the above formula (2-1) is plotted as the Y axis and the total content (atomic %) of nitrogen (N) and oxygen (O) is plotted as X axis, when the protective film 3 satisfies the conditions of the following formulas (2-1) and (2-2), it is possible to improve both the effect of preventing the diffusion of the components constituting the protective film 3 (particularly the components constituting the first layer 32) and the effect of improving the adhesion between the first layer 32 and the second layer 34. Y≧−0.0233X+0.14 (2-1) and Y≧0.0096X−0.144 (2-2)

[0132] FIG. 6 shows the inflection point x of the second aspect of the protective film 3 of this embodiment. １ 6 is a diagram for explaining the relationship between the total content (atomic %) of nitrogen (N) and oxygen (O) (X-axis) and the ratio A / M (Y-axis) of the content M of the metal element Em to the content A of the additional element Ea in the sample. The hatched area between the straight line of formula (2-1) and the straight line of formula (2-2) in FIG. 6 is the region of X and Y that satisfies the relationship between formula (2-1) and formula (2-2). For reference, values ​​of X and Y for Examples 1 to 10, which will be described later, are plotted in FIG. 6.

[0133] The protective film 3 of the second aspect of this embodiment has an inflection point x １ The ratio A / M (=Y) in the above formula does not necessarily need to be 0.020 or more.

[0134] In the protective film 3 of the second aspect of this embodiment, the ratio A / M, Y, is equal to or greater than zero (Y≧0), because the content M of the metal element Em and the content A of the additional element Ea cannot be negative values.

[0135] In the protective film 3 of the second aspect of this embodiment, the inflection point x １ The ratio A / M (=Y) in is preferably less than 0.17, more preferably 0.16 or less, and even more preferably 0.12 or less. By setting the upper limit of the ratio A / M (=Y) to a predetermined value, it is possible to prevent the reflectance of the multilayer reflective film-coated substrate 90 from being adversely affected by an excessively large content A of the additional element Ea.

[0136] The above formulas (2-1) and (2-2) were determined as follows.

[0137] First, it is believed that the greater the difference between the Fermi levels of the components contained in the first layer 32 and the second layer 34 of the protective film 3 of the second embodiment, the less likely the components (elements) will diffuse into each other at the interface between the first layer 32 and the second layer 34. Furthermore, the Fermi levels are relatively high for the additive element Ea, followed by the metal element Em and silicon nitride, with silicon oxide having the lowest. Therefore, since the Fermi levels of materials containing nitrogen (N) and / or oxygen (O) are relatively low compared to the Fermi levels of the additive element Ea and the metal element Em, it is believed that the use of materials containing nitrogen (N) and / or oxygen (O) improves the diffusion prevention performance. Therefore, the critical condition for achieving the desired diffusion prevention performance should be defined as [A / M] = a * [nitrogen (N) content + oxygen (O) content] + b, which is described by a negative slope a and a positive intercept b. In order to avoid confusion between the multiplication symbol and the letter "x," the multiplication symbol is represented by "*." As a result of investigation based on the results of several experiments, the inventors found that the slope a and intercept b of the equation for the critical condition are a = -0.0233 and b = 0.14, and obtained equation (2-1).

[0138] Next, it is believed that the greater the difference between the Fermi levels of the components contained in the first layer 32 and the second layer 34 of the protective film 3 of the second embodiment, the worse the adhesion at the interface between the first layer 32 and the second layer 34. Furthermore, the Fermi levels are relatively high for the additive element Ea, and decrease in the order of the metal element Em and silicon nitride, with silicon oxide being the lowest. Therefore, the Fermi levels of materials containing nitrogen (N) and / or oxygen (O) are relatively low compared to the Fermi levels of the additive element Ea and the metal element Em. Therefore, it is believed that the use of a material containing nitrogen (N) and / or oxygen (O) will worsen the adhesion at the interface between the first layer 32 and the second layer 34. On the other hand, since the additional element Ea can form coordinate bonds with nitrogen (N) and oxygen (O), it is believed that even if the nitrogen (N) and / or oxygen (O) content is high, it is possible to achieve the desired adhesion at the interface between the first layer 32 and the second layer 34 as long as the ratio A / M is large. Therefore, the critical condition for achieving the desired adhesion at the interface should be defined by a positive slope a and a negative intercept b, i.e., [A / M] = a * [nitrogen (N) content + oxygen (O) content] + b. Note that to avoid confusion between the multiplication symbol and the letter "x," the multiplication symbol is represented by "*" here. After conducting studies based on several experimental results, the inventors found that the slope a and intercept b of the critical condition equation are a = 0.0096 and b = -0.144, and thus obtained the following equation (2-2).

[0139] Therefore, by satisfying the above formulas (2-1) and (2-2), the protective film 3 of the second aspect of this embodiment is less likely to diffuse components (elements) into each other at the interface between the first layer 32 and the second layer 34, and the desired adhesion at the interface between the first layer 32 and the second layer 34 can be obtained.

[0140] Based on the above description, the multilayer reflective film coated substrate 90 including the protective film 3 of the second aspect of this embodiment can have the following configuration.

[0141] A multilayer reflective film coated substrate 90 including a protective film 3 according to a second aspect of this embodiment is 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, wherein the protective film includes a first layer and a second layer, and the first layer is disposed between the second layer and the multilayer reflective film, the protective film includes at least one metal element Em and at least one additional element Ea, and the content of the metal element Em in the second layer is higher than the content of the metal element Em in the first layer, the metal element Em is an element having a Fermi level of −4.7 eV or less, and the additional element Ea is an element having a Fermi level of more than −4.7 eV, and the protective film further includes at least one element selected from nitrogen (N) and oxygen (O), In the content distribution of the components contained in the protective film with respect to the position x in the thickness direction of the protective film, the position x at which the component of the second layer switches from being dominant to being dominant in the component of the first layer is defined as an inflection point x. １ When the content of the metal element Em is M, the content of the additional element Ea is A, the ratio A / M is Y, and the total content (atomic %) of nitrogen (N) and oxygen (O) is X, the inflection point x １ The multilayer reflective film-coated substrate is characterized in that the ratio A / M between Y and X satisfies the following relationships: Y≧−0.0233X+0.14 (2-1) and Y≧0.0096X−0.144 (2-2).

[0142] <<<<Third Aspect of Protective Film 3 >>>> Next, a third aspect of the protective film 3 of the multilayer reflective film coated substrate 90 of this embodiment will be described.

[0143] The protective film 3 of the third aspect of this embodiment includes a first layer 32 and a second layer 34, similar to the first and second aspects described above. The protective film 3 of the third aspect, like these aspects described above, has an inflection point x , which is the position x at which the component dominance of the second layer 34 switches to the component dominance of the first layer 32. １ The protective film 3 of the third embodiment has an inflection point x １ Distribution ratio y(x １ )(inflection point x １ Total content of the components of the first layer 32 at / inflection point x１ the total content of the components of the first layer 32 and the second layer 34 at the inflection point x １ Distribution ratio y(x １ ) slope y'(x １ ) is a specific relationship.

[0144] Specifically, the inflection point x １ Distribution ratio y(x １ ) is taken as the X axis, and the distribution ratio y(x １ ) slope y'(x １ In the graph with the Y axis representing the reflectivity (x / y) of the protective film 3, the reduction in EUV reflectivity due to long-term exposure can be controlled to a desired level or less by satisfying the condition of the following formula (3): Y≦−12.4*X+744 (3)

[0145] FIG. 7 shows the inflection point x of the third aspect of the protective film 3 of this embodiment. １ Distribution ratio y(x １ ) (X-axis), and the inflection point x １ Distribution ratio y(x １ ) slope y'(x １ 7 is a diagram for explaining the relationship between the X and Y axes. The region to the left of the straight line of formula (3) in FIG. 7 is the region of X and Y that satisfies the relationship of formula (3). For reference, the values ​​of X and Y for Examples 1 to 10, which will be described later, are plotted in FIG. 7, and Examples 1 to 5, 7, 9, and 10 satisfy the conditions of formula (3).

[0146] The above formula (3) was calculated as follows.

[0147] First, in order to suppress exposure contamination, such as the deposition of a carbon film on a reflective mask during EUV exposure, a technique of introducing hydrogen gas into the atmosphere during exposure is adopted. The protective film 3 of the third aspect includes a first layer 32 and a second layer 34. In such an exposure environment, the closer the compositions of the first layer 32 and the second layer 34 are (hereinafter referred to as "high homogeneity"), the more likely the phenomenon of hydrogen permeation from the second layer 34 to the first layer 32 occurs. Furthermore, the homogeneity of the first layer 32 and the second layer 34 is determined by the inflection point x １ Distribution ratio y(x １ ) and the distribution ratio y(x １The larger the distribution ratio y(x), the higher the homogeneity and the easier it is for hydrogen to permeate to the first layer 32. As a result, １ ) is larger, the more likely it is that the EUV reflectance will decrease due to long-term exposure. １ The rate of change of the distribution ratio in １ When the distribution ratio y(x １ ) and y'(x １ ) shows a positive correlation with y(x １ ) increases, the EUV reflectivity tends to decrease, and y'(x １ As the value of (3) increases, the EUV reflectivity tends to be less likely to decrease. As a result of investigations based on the results of several experiments, the present inventors have found that in order to control the decrease in EUV reflectivity due to long-term exposure to a desired level or less, it is necessary to satisfy the above formula (3).

[0148] Therefore, by satisfying the above formula (3), the protective film 3 of the third aspect of this embodiment is less likely to cause hydrogen to permeate from the second layer 34 to the first layer 32, making it less likely that a decrease in EUV reflectivity will occur due to long-term exposure.

[0149] Based on the above description, the multilayer reflective film coated substrate 90 including the protective film 3 of the third aspect of this embodiment can have the following configuration.

[0150] A multilayer reflective film coated substrate 90 including a protective film 3 according to a third aspect of this embodiment is 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, wherein the protective film includes a first layer and a second layer, and the first layer is disposed between the second layer and the multilayer reflective film, the protective film includes at least one metal element Em and at least one additional element Ea, and the content of the metal element Em in the second layer is higher than the content of the metal element Em in the first layer, the metal element Em is an element having a Fermi level of −4.7 eV or less, and the additional element Ea is an element having a Fermi level of more than −4.7 eV, and the position x at which the content distribution of components contained in the protective film changes from being dominated by the component of the second layer to being dominated by the component of the first layer with respect to a position x in the thickness direction of the protective film is defined as an inflection point x. １ and the inflection point x １ The distribution ratio at the inflection point x １ the total content of the components of the first layer at / the inflection point x １ wherein X is the total content of the components of the first layer and the components of the second layer in the matrix, and Y is the slope of X, the relationship between X and Y is Y≦−12.4*X+744.

[0151] <<Back Surface Conductive Film 5>> The multilayer reflective film-coated substrate 90 of this embodiment can have a back surface conductive film 5 for electrostatic chucks. The back surface conductive film 5 can be formed on the second main surface (backside main surface) of the substrate 1 (opposite the surface on which the multilayer reflective film 2 is formed, and on the intermediate layer if an intermediate layer such as a hydrogen penetration suppression film is formed on the substrate 1). The sheet resistance required for the back surface conductive film 5 for electrostatic chucks is typically 100 Ω / □ (Ω / square) or less. The back surface conductive film 5 can be formed by, for example, magnetron sputtering or ion beam sputtering using a target of a metal such as chromium or tantalum, or an alloy thereof. The chromium (Cr)-containing material of the back surface conductive film 5 is preferably a Cr compound containing Cr and at least one element selected from boron, nitrogen, oxygen, and carbon. 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, and carbon. 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.

[0152] It should be noted that the multilayer reflective film coated substrate 90 does not necessarily need to include the rear surface conductive film 5. For example, the rear surface conductive film 5 can be formed on the reflective mask blank 100 after forming the absorber film 4 described below.

[0153] <Reflective Mask Blank 100> The following describes the reflective mask blank 100 of this embodiment. As shown in Fig. 2, the reflective mask blank 100 of this embodiment has an absorber film 4 on the protective film 3 of the multilayer reflective film coated substrate 90 described above.

[0154] <<Absorber Film 4>> The absorber film 4 of the reflective mask blank 100 of this embodiment is formed on the protective film 3. The basic function of the absorber film 4 is to absorb EUV light. The absorber film 4 may be an absorber film 4 intended for absorbing EUV light, or an absorber film 4 having a phase shift function that also takes into account the phase difference of EUV light. An absorber film 4 having 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 having 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 film 2 via the protective film 3. Therefore, a desired phase difference is achieved 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 reflected light from the absorber film 4 and the reflected light from the multilayer reflective film 2 is 170 to 260 degrees. The lights with the inverted phase difference interfere with each other at the pattern edge, improving the image contrast of the projected optical image. As the image contrast improves, the resolution increases, and various exposure latitudes such as exposure dose latitude and focus latitude can be increased.

[0155] The absorber film 4 may be a single-layer film, or may be a multi-layer film consisting of multiple films (for example, a lower-layer absorber film (buffer layer) and an upper-layer absorber film). A single-layer film has the advantage of reducing the number of steps in mask blank manufacturing, thereby improving production efficiency. In the case of a multi-layer film, the optical constants and film thickness of the upper-layer absorber film can be appropriately set so that it serves as an anti-reflection film during optical mask pattern defect inspection. This improves inspection sensitivity during optical mask pattern defect inspection. Furthermore, using a film to which oxygen (O) or nitrogen (N), which improves oxidation resistance, is added as the upper-layer absorber film improves stability over time. In this way, various functions can be added by making the absorber film 4 a multi-layer film. When the absorber film 4 has a phase shift function, making it a multi-layer film can widen the range of optical adjustment, making it easier to obtain a desired reflectance.

[0156] The material of the absorber film 4 is not particularly limited as long as it has the function of absorbing EUV light, can be processed by etching or the like (preferably can be etched by dry etching with a chlorine (Cl)-based gas and / or a fluorine (F)-based gas), and has a high etching selectivity relative to the protective film 3 (second layer 34). As a material having such a function, at least one metal selected from palladium (Pd), silver (Ag), platinum (Pt), gold (Au), iridium (Ir), tungsten (W), chromium (Cr), cobalt (Co), manganese (Mn), tin (Sn), tantalum (Ta), vanadium (V), nickel (Ni), hafnium (Hf), iron (Fe), copper (Cu), tellurium (Te), zinc (Zn), magnesium (Mg), germanium (Ge), aluminum (Al), rhodium (Rh), ruthenium (Ru), molybdenum (Mo), niobium (Nb), titanium (Ti), zirconium (Zr), yttrium (Y), and silicon (Si), an alloy containing two or more metals, or a compound thereof can be preferably used. The compound may contain oxygen (O), nitrogen (N), carbon (C), and / or boron (B) in addition to the above metal or alloy.

[0157] The absorber film 4 can be formed by magnetron sputtering such as DC sputtering or RF sputtering. For example, the absorber film 4 made of a tantalum compound or the like can be formed by reactive sputtering using a target containing tantalum and boron and argon gas to which oxygen or nitrogen has been added.

[0158] Furthermore, in terms of smoothness and flatness, the crystalline state of the absorber film 4 is preferably an amorphous or microcrystalline structure. If the surface of the absorber film 4 is not smooth and flat, the edge roughness of the absorber pattern 4 a increases, which may result in poor dimensional accuracy of the pattern. 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).

[0159] In this embodiment, a reflective mask blank 100 having a structure in which a protective film 3 made of a material containing a metal is placed on a high refractive index layer can be obtained, which can suppress a decrease in the reflectivity of the multilayer reflective film 2 against EUV light even when heat treatment is performed on the reflective mask blank 100.

[0160] 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 of the absorber film 4 to the etching mask film 6 (etching rate of the absorber film 4 / etching rate of the etching mask film 6). The etching selectivity of the absorber film 4 to the etching mask film 6 is preferably 1.5 or more, and more preferably 3 or more.

[0161] The reflective mask blank 100 of this embodiment preferably has an etching mask film 6 on the absorber film 4 .

[0162] 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, 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).

[0163] 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.

[0164] 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.

[0165] 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.

[0166] <Reflective Mask 200> This embodiment is a reflective mask 200 having an absorber pattern 4a obtained by patterning the absorber film 4 of the above-described reflective mask blank.

[0167] As shown in FIG. 4( d ), the reflective mask 200 of this embodiment includes an absorber pattern 4 a obtained by patterning the absorber film 4 of the above-mentioned reflective mask blank 100 .

[0168] 4(a) to 4(d) are schematic diagrams 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.

[0169] First, a reflective mask blank 100 is prepared, which includes a substrate 1, a multilayer reflective film 2 formed on the substrate 1, a protective film 3 formed on the multilayer reflective film 2, and an absorber film 4 formed on the protective film 3. Next, a resist film 11 is formed on the absorber film 4 to obtain a reflective mask blank 100 with the resist film 11 (FIG. 4(a)). A pattern is written on the resist film 11 using an electron beam lithography device, and a resist pattern 11a is formed by further undergoing a development and rinsing process (FIG. 4(b)).

[0170] Using the resist pattern 11a as a mask, the absorber film 4 is dry-etched, whereby the portions of the absorber film 4 that are not covered by the resist pattern 11a are etched, and an absorber pattern 4a is formed (FIG. 4(c)).

[0171] 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 ３ In addition, a fluorine-based gas and / or a chlorine-based gas and O２ 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.

[0172] After the absorber pattern 4a is formed, the resist pattern 11a is removed using a resist remover solution. After the resist pattern 11a 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. 4(d)).

[0173] In addition, when a reflective mask blank 100 in which an etching mask film 6 is formed on an absorber film 4 is used, an additional process is performed in which a pattern (etching mask pattern) is formed on the etching mask film 6 using the resist pattern 11a as a mask, and then a pattern is formed on the absorber film 4 using the etching mask pattern as a mask.

[0174] 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.

[0175] The exposed region (reflective region) of the multilayer reflective film 2 covered with the protective film 3 has the function of reflecting EUV light. The region 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 can suppress a decrease in the reflectivity of the reflective region for EUV light even when subjected to heat treatment. By using the reflective mask 200 of this embodiment, a reflective region that maintains high reflectivity for EUV light can be obtained, making it possible to transfer finer patterns onto a transfer target in EUV lithography.

[0176] In the reflective mask 200 of this embodiment, it is possible to improve the adhesion at the interface between the first layer 32 and the second layer 34 of the protective film 3. Therefore, it is possible to suppress the occurrence of film peeling defects in the reflective mask 200 of this embodiment. Furthermore, in the reflective mask 200 of this embodiment, it is possible to improve the adhesion at the interface between the first layer 32 and the second layer 34 of the protective film 3, maintain high reflectivity for EUV light, and maintain high etching resistance of the protective film 3. Therefore, the reflective mask 200 of this embodiment can be used for manufacturing high-performance semiconductor devices.

[0177] <Method for Manufacturing Semiconductor Device> The method for manufacturing a semiconductor device according to this embodiment includes a step of performing a lithography process using an exposure apparatus and the above-described reflective mask 200 to form a transfer pattern on a transfer target.

[0178] 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.

[0179] According to this embodiment, a semiconductor device can be manufactured using a multilayer reflective film coated substrate 90 that can suppress a decrease in the reflectivity of the multilayer reflective film 2 for EUV light even when heat treatment is performed, and a reflective mask 200 made from a reflective mask blank 100. Therefore, by using the reflective mask 200 of this embodiment, it is possible to manufacture semiconductor devices with higher density and precision.

[0180] 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.

[0181] 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.

[0182] 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.

[0183] The EUV light reflected by the reflective mask 200 is reduced by the projection optical system 57 to a pattern image light, typically about one-fourth the original size, and projected onto the semiconductor substrate 60 (transferred substrate). As a result, a given circuit pattern is transferred onto a resist film on the semiconductor substrate 60. A resist pattern can be formed on the semiconductor substrate 60 by developing the exposed resist film. An integrated circuit pattern can be formed on the semiconductor substrate 60 by etching the semiconductor substrate 60 using the resist pattern as a mask. A semiconductor device is manufactured through these and other necessary processes.

[0184] Examples 1 to 10 are described below, but the present invention is not limited to these examples.

[0185] As Examples 1 to 10, a multilayer reflective film coated substrate 90 was produced in which a multilayer reflective film 2 and a protective film 3 were formed on the first main surface of a substrate 1 .

[0186] Table 1 shows the types of Em and Ea elements contained in the protective films 3 of Examples 1 to 10, the gas flow conditions during deposition of the second layer 34, and the continuity of the deposition process. The continuity of the deposition process indicates whether the second layer 34 was deposited continuously in the deposition apparatus without being taken out into the atmosphere after deposition of the first layer 32. Table 1 also shows the composition of the target used to deposit the second layer 34 of the protective films 3 of Examples 1 to 10.

[0187] The multilayer reflective film coated substrates 90 of Examples 1 to 10 were fabricated as follows.

[0188] A SiO 6025 size (approximately 152 mm x 152 mm x 6.35 mm) low thermal expansion glass substrate 1 with both the first and second main surfaces 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.

[0189] Next, a multilayer reflective film 2 was formed on the first main surface of the substrate 1. The multilayer reflective film 2 was a periodic multilayer reflective film 2 made of Si and Mo to be suitable for EUV light with a wavelength of 13.5 nm. Specifically, a Si target and a Mo target were used as the high-refractive index material target and the low-refractive index material target. Krypton (Kr) ion particles were supplied from an ion source to these targets to perform ion beam sputtering, thereby alternately laminating Si layers and Mo layers on the substrate 1.

[0190] Here, the Si and Mo sputtered particles were incident at an angle of 30 degrees with respect to the normal to the first main surface of the substrate 1. First, a Si layer was formed to a thickness of 4.2 nm, followed by a Mo layer to a thickness of 2.8 nm. This constitutes one cycle, and 40 cycles were stacked in the same manner. Therefore, the material of the bottom layer of the multilayer reflective film 2, i.e., the material of the multilayer reflective film 2 closest to the substrate 1, was Si, and the material of the top layer of the multilayer reflective film 2 was Mo.

[0191] Next, a protective film 3 consisting of a first layer 32 and a second layer 34 was formed on the multilayer reflective film 2 of Examples 1 to 10.

[0192] First, a first layer 32 of the protective film 3 was formed on the surface of the multilayer reflective film 2. The first layer 32 was formed under the same conditions as the method for forming the Si layer of the multilayer reflective film 2 described above. At this time, the first layer 32 was formed so that the film thickness of the first layer 32 would be 4.0 nm, based on the relationship between the film formation rate and film formation time of the Si layer under predetermined conditions.

[0193] Next, a second layer 34 was formed on the surface of the first layer 32. Table 1 shows the continuity of the film formation process between the formation of the first layer 32 and the formation of the second layer 34. In Table 1, "continuous" indicates that after the formation of the first layer 32, the sample was not taken out into the atmosphere, and the second layer 34 was continuously formed in the film formation apparatus. In Table 1, "discontinuous" indicates that after the formation of the first layer 32, the sample was taken out into the atmosphere, and then the sample was placed in the film formation apparatus to form the second layer 34. The second layer 34 was formed using a sintered target having the composition shown in Table 1, and nitrogen (N ２ ) gas and / or argon (Ar) gas flow rate ratio N ２ The film was formed by DC magnetron sputtering (reactive sputtering) in a gas atmosphere containing Ar / Ar (flow rate unit: sccm: Standard Cubic Centimeter per Minute).

[0194] Next, the content distribution of each component (element) was obtained by measuring the content of each component with respect to the position x in the film thickness direction (depth direction) of the protective film 3 (first layer 32 and second layer 34) of Examples 1 to 10. The content distribution of each component was measured by energy dispersive X-ray spectroscopy (EDX) using a scanning transmission electron microscope (STEM).

[0195] Next, based on the measured values ​​of the content of each component at a position x in the thickness direction of the protective film 3, the following distribution ratio y(x) at the position x was calculated.

[0196] y(x)=(total content of components in the first layer 32 at position x) / (total content of components in the first layer 32 and the second layer 34 at position x)

[0197] Next, the distribution ratio y(x) was curve-fitted with a quartic function to obtain a quartic function y(x) corresponding to the distribution ratio y(x). The start and end points of x for curve fitting were determined as follows. The start point of curve fitting (the origin of the position x in the film thickness direction) was set to the position of x = 0 (the origin), and the end point of curve fitting was set to the position of x = D. The position (depth) of x = D in the protective film 3 is a position (depth) closer to the interface between the protective film 3 and the multilayer reflective film than the position (depth) of x = 0.

[0198] The starting point of the curve fitting (x = 0) was the position (depth) where the total content (atomic %) of the Em element and the Ea element among the contents of each component was at its maximum. The position of x = D (end point of the curve fitting range) was determined by the coefficient of determination R of the curve fitting by the quartic function in the range of x where the total content (atomic %) of the Em element and the Ea element decreases from its maximum value to 5 atomic % or more and 20 atomic % or less. ２ The point x where x=D was the maximum value within that range of x. The range of x from x=0 to x=D was set to be the range in the film thickness direction (depth direction) that was considered to include the interface between the first layer 32 and the second layer 34. The distribution ratio y(x) obtained as described above was curve-fitted with a quartic function within the range from the start point (x=0) to the end point (x=D) to obtain a quartic function y(x) corresponding to the distribution ratio y(x).

[0199] The inflection point x of this quartic function y(x) １ By calculating the above, the position corresponding to the interface between the first layer 32 and the second layer 34 was identified. １ can be obtained by finding the solution of y''(x)=0 for the second derivative y''(x), which is the second derivative of the quartic function y(x).

[0200] Table 2 shows the content (atomic %) of each element at the start point (x=0) of the curve fitting. Note that this value is the content at the position where the total content (atomic %) of the Em element and the Ea element is at its maximum, and therefore can also be said to be the composition at the center of the second layer 34. Table 3 shows the total content (atomic %) of the Em element and the Ea element at the start point (x=0) of the curve fitting, the depth D (nm) in the film thickness direction which is the end point of the curve fitting, and the coefficient of determination R of the curve fitting by the quartic function y(x). ２ The maximum value of the quartic function y(x) and the inflection point x １ (nm), inflection point x １ The first derivative of the quartic function y(x) at １ )) and the inflection point x １ The value of the quartic function y(x) at １ )) indicates.

[0201] Table 4 shows the inflection point x １ The composition (atomic %) at the interface between the first layer 32 and the second layer 34, the total content (M+A) of the Em element and the Ea element, and the ratio (A / M) of the content M of the metal element Em to the content A of the additional element Ea are shown.

[0202] (Measurement of reflectivity of multilayer reflective film coated substrate 90 to EUV light) Using the multilayer reflective film coated substrates 90 of Examples 1 to 10 prepared as described above, the reflectivity (unit: %) of the multilayer reflective film coated substrate 90 to EUV light was measured. Table 4 shows the measurement results of the reflectivity (unit: %) of the multilayer reflective film coated substrates 90 of Examples 1 to 10 to EUV light.

[0203] As shown in Table 4, the reflectance to EUV light of the multilayer reflective film-coated substrates 90 of Examples 1 to 10 ranged from 62.9% (Example 3) to 64.2% (Example 9). Therefore, it can be said that the reflectance to EUV light of the multilayer reflective film-coated substrates 90 of Examples 1 to 10 is all high enough to be usable as a reflective mask 200.

[0204] As shown in Table 4, no film peeling defects were observed in the multilayer reflective film coated substrates 90 of Examples 1 to 6. １The ratio (A / M) of the content M of the metal element Em to the content A of the additive element Ea (at the interface between the first layer 32 and the second layer 34) was in the range of 0.024 to 0.110. On the other hand, in the multilayer reflective film coated substrates 90 of Examples 7 to 10, although the reflectivity was high, film peeling defects were observed after the formation of the absorber film 4 described below. Inflection points x １ The ratio (A / M) of the content M of the metal element Em to the content A of the additional element Ea is in the range of 0 to 0.017.

[0205] From the above, it can be said that the multilayer reflective film coated substrates 90 of Examples 1 to 6 of this embodiment, which have the first aspect of the protective film 3, were able to improve the adhesion between the first layer 32 and the second layer 34 of the protective film 3 while maintaining high reflectivity for EUV light.

[0206] As shown in FIG. 6, in the protective films 3 of Examples 1 to 3 and 5 and 6, the inflection point x １ The ratio A / M (=Y) at the interface (between the first layer 32 and the second layer 34) satisfies the formulas (2-1) and (2-1) of the second aspect of this embodiment. Therefore, it can be said that the multilayer reflective film-coated substrate 90 of the second aspect of this embodiment has been able to improve the adhesion between the first layer 32 and the second layer 34 of the protective film 3 while maintaining high reflectivity for EUV light.

[0207] In addition, since the Fermi level of a material containing nitrogen (N) and / or oxygen (O) is relatively small compared to the Fermi level of the additive element Ea and the metal element Em, it is considered that the diffusion prevention performance is improved by using a material containing nitrogen (N) and / or oxygen (O). １ (the interface between the first layer 32 and the second layer 34), it is believed that the diffusion prevention performance is improved. １ Since the position (the interface between the first layer 32 and the second layer 34) does not contain detectable amounts of nitrogen (N) and oxygen (O), it is believed that the effect of the diffusion prevention performance resulting from nitrogen (N) and / or oxygen (O) as in Examples 1 to 3 and 5 and 6 cannot be obtained.

[0208] As shown in FIG. 7, in the protective films 3 of Examples 1 to 5, 7, 9, and 10, the inflection point x １ The distribution ratio (inflection point x １ Total content of the components of the first layer 32 at / inflection point x １ the total content of the components of the first layer 32 and the second layer 34 at the inflection point x １ The rate of change in the distribution ratio, i.e., the slope (=Y), satisfies the relationship of formula (3) in the third aspect of this embodiment. Therefore, it can be said that the multilayer reflective film coated substrate 90 in the third aspect of this embodiment was able to control the decrease in EUV reflectivity due to long-term exposure to a desired level or less.

[0209] (Reflective Mask Blank 100) Next, the reflective mask blanks 100 of Examples 1 to 10 will be described.

[0210] A back surface conductive film 5 was formed on the back surface of the substrate 1 of the multilayer reflective film coated substrate 90 manufactured under the same conditions as described above, and an absorber film 4 was formed on the protective film 3, thereby producing the reflective mask blanks 100 of Examples 1 to 10.

[0211] First, a back surface conductive film 5 made of a CrN film was formed on the second main surface (back surface) of the substrate 1 of the multilayer reflective film coated substrate 90 by magnetron sputtering (reactive sputtering) under the following conditions: Conditions for forming the back surface conductive film 5: Cr target, Ar and N ２ A mixed gas atmosphere (Ar: 90%, N: 10%), film thickness 20 nm.

[0212] Next, a TaBN film having a thickness of 55 nm was formed as an absorber film 4 on the protective film 3 of the multilayer reflective film-coated substrate 90. The composition of the absorber film 4 was Ta:B:N=75:12:13 (atomic ratio), and the film thickness was 55 nm.

[0213] In this manner, the reflective mask blank 100 of the example was manufactured.

[0214] (Method for detecting and determining film peeling defects in reflective mask blank 100) Next, a method for detecting and determining film peeling defects in the reflective mask blank 100 will be described. Film peeling defects were detected by inspecting the surface of the absorber film 4, which is the outermost layer of the reflective mask blank 100, using a defect inspection device for the reflective mask blank 100 that is capable of detecting defects with a height of 4 nm or more and a width of 80 nm or more. The detected defects included, in addition to film peeling defects, general defects that may occur in the manufacturing process of the reflective mask blank 100 due to the film formation process and cleaning process, so the presence or absence of film peeling defects was determined by observing the cross sections of these defects using a scanning transmission electron microscope (STEM). Table 4 shows the results of determining the presence or absence of film peeling defects in the reflective mask blanks 100 of Examples 1 to 10.

[0215] (Reflective Mask 200) Next, the reflective mask blanks 100 of Examples 1 to 6 that were free of film peeling defects were used to manufacture reflective masks 200. The manufacture of the reflective mask 200 will be described with reference to FIG.

[0216] First, as shown in Fig. 4(a), a resist film 11 was formed on the absorber film 4 of the reflective mask blank 100. Then, a desired pattern such as a circuit pattern was drawn (exposed) on this resist film 11, and then developed and rinsed to form a predetermined resist pattern 11a (Fig. 4(b)). Next, using the resist pattern 11a as a mask, the absorber film 4 (TaBN film) was etched with Cl ２ Dry etching was performed using gas to form an absorber pattern 4a (FIG. 4(c)), after which the resist pattern 11a was removed (FIG. 4(d)).

[0217] Finally, wet cleaning was performed using deionized water (DIW), and the reflective masks 200 of Examples 1 to 6 were manufactured.

[0218] (Manufacturing of semiconductor device) The reflective masks 200 of Examples 1 to 6 were 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 was formed on the semiconductor substrate 60 on which the processed film was formed.

[0219] It is believed that the reflective masks 200 of Examples 1 to 6 were able to improve the adhesion between the first layer 32 and the second layer 34 because the protective film 3 included the predetermined first layer 32 and second layer 34. Therefore, by using the reflective masks 200 of Examples 1 to 6, it was possible to form a fine and highly accurate transfer pattern (resist pattern) on the semiconductor substrate 60 (transferred substrate).

[0220] This resist pattern is transferred to the film to be processed by etching, and then various processes such as forming insulating and conductive films, introducing dopants, and annealing are carried out, allowing semiconductor devices with the desired characteristics to be manufactured with a high yield.

[0221]

[0222]

[0223]

[0224]

[0225] 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 11 resist film 11a resist pattern 32 first layer 34 second 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 90 substrate with multilayer reflective film 100 reflective mask blank 200 reflective mask

Claims

1. A multilayer reflective substrate having a substrate, a multilayer reflective film provided on the substrate, and a protective film provided on the multilayer reflective film, The protective film comprises a first layer and a second layer, the first layer being disposed between the second layer and the multilayer reflective film. The protective film comprises at least one metal element Em and at least one additive element Ea, wherein the content of the metal element Em in the second layer is greater than the content of the metal element Em in the first layer. The aforementioned metallic element Em is an element having a Fermi level of -4.7 eV or lower. The aforementioned additive element Ea is an element having a Fermi level greater than -4.7 eV, In the distribution of component content in the protective film with respect to position x in the film thickness direction, the position x at which the distribution switches from a component dominance of the second layer to a component dominance of the first layer is defined as an inflection point x. １ Let M be the content of the metal element Em and A be the content of the additive element Ea, then the inflection point x １ A multilayer reflective substrate characterized by having a ratio A / M of 0.020 or higher.

2. The substrate with a multilayer reflective film according to claim 1, wherein the metallic element Em is one or more elements selected from ruthenium (Ru), rhodium (Rh), and iridium (Ir).

3. The substrate with a multilayer reflective film according to claim 1, wherein the additive element Ea is one or more elements selected from Tl, Hf, Ti, Zr, Y, Mn, In, Ga, Cd, Bi, Ta, Pb, Ag, Al, V, Sn, Zn, Hg, Cr, Fe, Sb, W, Mo, and Cu.

4. The aforementioned inflection point x １ The multilayer reflective substrate according to claim 1, wherein the content A of the additive element Ea in the substrate is 1 atomic% or more and 15 atomic% or less.

5. The aforementioned inflection point x １ The multilayer reflective substrate according to claim 1, wherein the content M of the metal element Em in the substrate is 5 atomic percent or more and 80 atomic percent or less.

6. The aforementioned inflection point x １ The multilayer reflective substrate according to claim 1, wherein the ratio A / M in is less than 0.

17.

7. The additive element Ea is Nb, The multilayer reflective substrate according to claim 1, wherein the content of the additive element Ea at the position where the total content of the metal element Em and the additive element Ea is at its maximum value is 8 atomic percent or less.

8. The first layer comprises silicon (Si) and at least one selected from nitrogen (N) and oxygen (O), and the inflection point x １ The multilayer reflective substrate according to claim 1, wherein the total content of nitrogen (N) and oxygen (O) in the substrate is 2 atomic percent or more.

9. The aforementioned inflection point x １ The multilayer reflective substrate according to claim 8, wherein the total content of nitrogen (N) and oxygen (O) in the substrate is 35 atomic percent or less.

10. A reflective mask blank characterized in that it has an absorbent film on the protective film of a multilayer reflective film substrate according to any one of claims 1 to 9.

11. A reflective mask characterized in that it has an absorber pattern on the protective film of a multilayer reflective film substrate according to any one of claims 1 to 9.

12. A method for manufacturing a semiconductor device, characterized by comprising the step of performing a lithography process using an exposure apparatus with a reflective mask as described in claim 11 to form a transfer pattern on a transfer object.