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

Abstract

Provided is a substrate having a multilayer reflective film, the substrate being used in order to produce a reflective mask blank and a reflective mask having a multilayer reflective film that has high reflectance to exposure light and a low background level during inspection of defects.　A substrate 110 having a multilayer reflective film comprises a substrate 1 and a multilayer reflective film 5. The multilayer reflective film 5 is composed of a multilayer film in which low-refractive-index layers and high-refractive-index layers are alternately laminated on the substrate 1. The multilayer reflective film 5 includes at least one additive element selected from hydrogen (H), deuterium (D), and helium (He). The atom density of the additive element in the multilayer reflective film 5 is 0.006 atoms / nm3 to 0.50 atoms / nm3 (inclusive).

Description

[Technical Field]

[0001] The present invention relates to a reflective mask used in the manufacture of semiconductor devices, 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. [Background technology]

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

[0003] Light incident on a reflective mask set in an exposure tool is absorbed in areas with an absorber film and reflected by a multilayer reflective film in areas without an absorber film. The reflected image is transferred onto a semiconductor substrate through a reflective optical system to form a mask pattern. Known examples of such multilayer reflective films include those made by alternatingly stacking Mo and Si layers several nanometers thick to reflect EUV light with a wavelength of 13 to 14 nm.

[0004] As a technology for manufacturing a substrate having such a multilayer reflective film, Patent Document 1 describes an integrated extreme ultraviolet blank production system including a vacuum chamber for placing a substrate in a vacuum, a deposition system for depositing a multilayer stack without removing the substrate from the vacuum, and a processing system for processing a layer on the multilayer stack deposited as an amorphous metal layer. The amorphous metal layer is described as being made of amorphous molybdenum, further alloyed with boron, nitrogen, or carbon.

[0005] Patent Document 2 describes a multilayer reflector for soft X-rays and vacuum ultraviolet rays having a multilayer thin film structure consisting of alternating layers of high and low absorption layers for soft X-rays and vacuum ultraviolet rays, characterized in that the high absorption layers contain one or more of boride, carbide, silicide, nitride, and oxide of a transition metal as a main component, and the low absorption layers contain one or more of carbon, silicon, boron, or beryllium as a simple substance or compounds of each of these elements as a main component.

[0006] Patent Document 3 describes a technique for smoothing the interfaces and surfaces of a multilayer reflective film by hydrogenating the interfaces of each layer of the multilayer reflective film to prevent interlayer diffusion and form smooth interfaces.

[0007] Patent Document 4 describes a method for manufacturing a substrate with a reflective layer for EUV lithography (EUVL), which forms a reflective layer that reflects EUV light on a substrate, wherein the reflective layer is a Mo / Si multilayer reflective film, which is formed by a sputtering method in an atmosphere containing an inert gas containing at least one of helium (He), argon (Ar), neon (Ne), krypton (Kr), and xenon (Xe), and hydrogen (H), and the method includes a step of heat-treating the formed Mo / Si multilayer reflective film at a temperature of 120 to 160°C. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Special Publication No. 2016-519329 [Patent Document 2] Special Publication No. 7-97159 [Patent Document 3] Japanese Patent Application Publication No. 5-297194 [Patent Document 4] Patent Publication No. 2013-122952 Summary of the Invention [Problem to be solved by the invention]

[0009] In view of the improvement in defect quality accompanying the recent trend toward finer patterns and the optical properties required of reflective masks (such as the surface reflectivity of the multilayer reflective film), the interfaces of each layer of the multilayer reflective film and / or the surface of the multilayer reflective film are required to have higher smoothness. By smoothing the surface of the multilayer reflective film-coated substrate, which is the target of defect inspection, i.e., the interfaces of each layer of the multilayer reflective film and / or the surface of the multilayer reflective film, and reducing noise (background noise) caused by the roughness of the interfaces of each layer of the multilayer reflective film and / or the roughness of the surface of the multilayer reflective film, it becomes possible to more reliably detect minute defects (defect signals) present in the multilayer reflective film-coated substrate.

[0010] Furthermore, during exposure using a reflective mask, the exposure light is absorbed by the absorber film formed in a pattern, and the exposure light is reflected by the multilayer reflective film at the exposed portions of the multilayer reflective film. In order to obtain high contrast during exposure, it is desirable that the multilayer reflective film have a high reflectance with respect to the exposure light.

[0011] One possible way to increase the reflectivity of a multilayer reflective coating to exposure light is to improve the crystallinity of each layer constituting the multilayer reflective coating (by increasing the crystal grain size). However, increasing the crystal grain size increases noise (background level: BGL) during defect inspection, resulting in an increase in the time required for defect inspection. This is because if the background level during defect inspection becomes too high, noise is detected as a defect, and it takes a long time to distinguish between real defects that contribute to transfer and false defects that do not. Furthermore, a high background level during defect inspection can cause real defects that contribute to transfer to be mistaken for noise and not be detected. The problem of an increased background level is thought to be due to the coarsening of crystal grains, which deteriorates the smoothness of the interfaces of each layer of the multilayer reflective coating and / or the surface of the multilayer reflective coating. The deterioration of the smoothness of the interfaces of each layer of the multilayer reflective coating and / or the surface of the multilayer reflective coating increases the scattering of the inspection light irradiated during defect inspection, which is thought to cause an increase in the background level during defect inspection.

[0012] Therefore, an object of the present invention is to provide a reflective mask blank and a reflective mask having a multilayer reflective film that has a high reflectance to exposure light and a low background level during defect inspection. Another object of the present invention is to provide a multilayer reflective film-coated substrate used for manufacturing a reflective mask blank and a reflective mask having a multilayer reflective film that has a high reflectance to exposure light and a low background level during defect inspection. A further object of the present invention is to provide a method for manufacturing a semiconductor device using the above reflective mask.

[0013] Another object of the present invention is to provide a multilayer reflective film-coated substrate, a reflective mask blank, and a reflective mask that can more reliably detect actual defects that contribute to transfer. [Means for solving the problem]

[0014] In order to solve the above problems, the present invention has the following configuration.

[0015] (Configuration 1) A multilayer reflective film-coated substrate comprising a substrate and a multilayer reflective film for reflecting exposure light, the multilayer reflective film being made up of a multilayer film in which low refractive index layers and high refractive index layers are alternately laminated on the substrate, the multilayer reflective film contains at least one additive element selected from hydrogen (H), deuterium (D), and helium (He), The atomic density of the additive element in the multilayer reflective film is 0.006 atom / nm 3 More than 0.50atom / nm 3 A multilayer reflective film-coated substrate characterized by:

[0016] (Configuration 2) The atomic density of the additive element in the multilayer reflective film is 0.10 atom / nm 3 A multilayer reflective film-coated substrate according to Configuration 1, characterized in that:

[0017] (Configuration 3) 3. The multilayer reflective film coated substrate according to configuration 1 or 2, wherein the additional element is deuterium (D).

[0018] (Configuration 4) 4. The multilayer reflective film coated substrate according to any one of configurations 1 to 3, further comprising a protective film on the multilayer reflective film.

[0019] (Configuration 5) A reflective mask blank comprising an absorber film on the multilayer reflective film of the multilayer reflective film-coated substrate according to any one of Structures 1 to 3, or on the protective film of the multilayer reflective film-coated substrate according to Structure 4.

[0020] (Configuration 6) A reflective mask comprising an absorber pattern formed by patterning the absorber film of the reflective mask blank according to Configuration 5.

[0021] (Configuration 7) A method for manufacturing a semiconductor device, comprising the step of performing a lithography process using an exposure apparatus with the reflective mask according to configuration 6 to form a transfer pattern on a transfer target. [Effects of the Invention]

[0022] The present invention can provide a reflective mask blank and a reflective mask having a multilayer reflective film that has a high reflectance to exposure light and a low background level during defect inspection. The present invention can also provide a multilayer reflective film-coated substrate used for manufacturing a reflective mask blank and a reflective mask having a multilayer reflective film that has a high reflectance to exposure light and a low background level during defect inspection. Furthermore, the present invention can provide a method for manufacturing a semiconductor device using the above-mentioned reflective mask.

[0023] Furthermore, the present invention can provide a multilayer reflective film coated substrate, a reflective mask blank, and a reflective mask that can more reliably detect real defects that contribute to transfer. [Brief explanation of the drawings]

[0024] [Figure 1] FIG. 1 is a cross-sectional view schematically illustrating an example of a multilayer reflective film-coated substrate. [Figure 2] FIG. 2 is a cross-sectional view schematically illustrating another example of a multilayer reflective film-coated substrate. [Figure 3] FIG. 1 is a schematic cross-sectional view of an example of a reflective mask blank. [Figure 4] 1A to 1C are process diagrams showing a method for manufacturing a reflective mask in the form of schematic cross-sectional views. DETAILED DESCRIPTION OF THE INVENTION

[0025] 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.

[0026] Fig. 1 shows a cross-sectional schematic diagram of one example of a multilayer reflective film-coated substrate 110 according to an embodiment of the present invention. As shown in Fig. 1, the multilayer reflective film-coated substrate 110 according to this embodiment includes a multilayer reflective film 5 on a substrate 1. The multilayer reflective film 5 is a film for reflecting exposure light, and is made of a multilayer film in which low refractive index layers and high refractive index layers are alternately stacked. The multilayer reflective film-coated substrate 110 according to this embodiment may include a back surface conductive film 2 on the back surface of the substrate 1 (the main surface opposite to the main surface on which the multilayer reflective film 5 is formed).

[0027] 2 is a schematic cross-sectional view of another example of the multilayer reflective film coated substrate 110 of this embodiment. In the example shown in FIG.

[0028] A reflective mask blank 100 can be manufactured using the multilayer reflective film coated substrate 110 of this embodiment. Fig. 3 shows a schematic cross-sectional view of an example of the reflective mask blank 100. The reflective mask blank 100 further includes an absorber film 7.

[0029] Specifically, the reflective mask blank 100 of this embodiment has an absorber film 7 on the outermost surface (for example, the surface of the multilayer reflective film 5 or the protective film 6) of the multilayer reflective film-coated substrate 110. By using the reflective mask blank 100 of this embodiment, a reflective mask 200 having a multilayer reflective film 5 with high reflectivity to EUV light can be obtained.

[0030] In this specification, a "multilayer reflective film coated substrate 110" refers to a substrate having a multilayer reflective film 5 formed on a predetermined substrate 1. FIGS. 1 and 2 show examples of schematic cross-sectional views of a multilayer reflective film coated substrate 110. The "multilayer reflective film coated substrate 110" also includes a substrate having a thin film other than the multilayer reflective film 5, such as a protective film 6 and / or a back surface conductive film 2, formed thereon. In this specification, a "reflective mask blank 100" refers to a multilayer reflective film coated substrate 110 having an absorber film 7 formed thereon. The "reflective mask blank 100" also includes a substrate having a thin film other than the absorber film 7 (for example, an etching mask film and a resist film 8) further formed thereon.

[0031] In this specification, "disposing (forming) the absorber film 7 on the multilayer reflective film 5" not only refers to the case where the absorber film 7 is disposed (formed) in contact with the surface of the multilayer reflective film 5, but also includes the case where another film exists between the multilayer reflective film 5 and the absorber film 7. The same applies to other films. In addition, in this specification, for example, "disposing film A in contact with the surface of film B" means that film A and film B are disposed so as to be in direct contact with each other, with no other film interposed between them.

[0032] <Substrate 110 with multilayer reflective film> The substrate 1 and each thin film constituting the multilayer reflective film coated substrate 110 of this embodiment will be described below.

[0033] <<Board 1>> The substrate 1 in the multilayer reflective film coated substrate 110 of this embodiment preferably has a small distortion of the absorber pattern due to heat during EUV exposure. Therefore, a substrate having a low thermal expansion coefficient within the range of 0±5 ppb / °C is preferably used as the substrate 1. Examples of materials having a low thermal expansion coefficient within this range include SiO2-TiO2-based glass and multi-component glass ceramics.

[0034] The first main surface of the substrate 1, on which a transfer pattern (constituting the absorber film 7 described below) is formed, is surface-processed to a predetermined flatness in order to ensure at least pattern transfer accuracy and positional accuracy. In the case of EUV exposure, the flatness is preferably 0.1 μm or less, more preferably 0.05 μm or less, and even more preferably 0.03 μm or less, in a 132 mm × 132 mm area of ​​the main surface of the substrate 1 on which the transfer pattern is formed. The second main surface (rear surface) opposite the side on which the absorber film 7 is formed is the surface that is electrostatically chucked when set in an exposure tool. The flatness of the second main surface is preferably 0.1 μm or less, more preferably 0.05 μm or less, and even more preferably 0.03 μm or less, in a 142 mm × 142 mm area.

[0035] The surface smoothness of the substrate 1 is also important. The surface roughness of the first main surface on which the absorber pattern 7a is formed is preferably 0.15 nm or less in root mean square roughness (Rms), more preferably 0.10 nm or less in Rms. The surface smoothness can be measured with an atomic force microscope.

[0036] Furthermore, the substrate 1 preferably has high rigidity to prevent deformation due to film stress of films (such as the multilayer reflective film 5) formed on the substrate 1. In particular, the substrate 1 preferably has a high Young's modulus of 65 GPa or more.

[0037] <<Base film>> The multilayer reflective film coated substrate 110 of this embodiment may have an underlayer film 3 in contact with the surface of the substrate 1. The underlayer film 3 is a thin film formed between the substrate 1 and the multilayer reflective film 5. The underlayer film 3 may be a film having a function according to the purpose. For example, the underlayer film 3 may be a conductive layer that prevents charge-up during mask pattern defect inspection using an electron beam. The underlayer film 3 may be a planarizing layer that improves the flatness of the surface of the substrate 1. The underlayer film 3 may be a smoothing layer that improves the flatness of the surface of the substrate 1.

[0038] The material of the conductive underlayer is preferably a material containing ruthenium or tantalum as a main component. For example, it may be Ru metal alone or Ta metal alone, or it may be a Ru alloy or Ta alloy containing Ru or Ta with at least one metal selected from titanium (Ti), niobium (Nb), molybdenum (Mo), zirconium (Zr), yttrium (Y), boron (B), lanthanum (La), cobalt (Co), and rhenium (Re). The thickness of the underlayer is preferably in the range of, for example, 1 nm to 10 nm.

[0039] Furthermore, as a material for the undercoat film for improving the flatness and smoothness, silicon or a material containing silicon as a main component is preferably used. The material for the undercoat film may be, for example, silicon (Si) alone, or a material containing oxygen (O) and nitrogen (N) in Si, such as SiO2 or SiO x(x<2), SiON, Si3N4, Si x N y It may also be a silicon compound where x is 3 and y is a natural number other than 4. As described above, the thickness of the undercoat film is preferably in the range of 1 nm to 10 nm, for example.

[0040] <<Multilayer reflective film 5>> The multilayer reflective film 5 provides the reflective mask 200 with the function of reflecting EUV light. The multilayer reflective film 5 is a multilayer film in which layers containing elements with different refractive indices as main components are periodically stacked.

[0041] Generally, the multilayer reflective film 5 is a multilayer film in which thin films (high refractive index layers) of light elements or compounds thereof, which are high refractive index materials, and thin films (low refractive index layers) of heavy elements or compounds thereof, which are low refractive index materials, are alternately stacked in approximately 40 to 60 cycles (pairs).

[0042] The multilayer film used as the multilayer reflective film 5 includes a "high refractive index layer / low refractive index layer" stacked structure in which a high refractive index layer and a low refractive index layer are stacked in this order from the substrate 1 side. Multiple cycles of this stacked structure may be stacked, with one "high refractive index layer / low refractive index layer" being one cycle. Alternatively, the multilayer film used as the multilayer reflective film 5 includes a "low refractive index layer / high refractive index layer" stacked structure in which a low refractive index layer and a high refractive index layer are stacked in this order from the substrate 1 side. Multiple cycles of this stacked structure may be stacked, with one "low refractive index layer / high refractive index layer" being one cycle. The top layer of the multilayer reflective film 5, i.e., the surface layer of the multilayer reflective film 5 opposite the substrate 1 side, is preferably a high refractive index layer. In the above-described multilayer film, when a high refractive index layer and a low refractive index layer are stacked in this order from the substrate 1 side, the top layer is a low refractive index layer. In this case, the low refractive index layer is the top surface of the multilayer reflective film 5, and therefore the top surface of the multilayer reflective film 5 is easily oxidized, reducing the reflectance of the reflective mask 200. Therefore, it is preferable to form a high-refractive index layer on the uppermost low-refractive index layer. On the other hand, in the above-mentioned multilayer film, if a low-refractive index layer and a high-refractive index layer are stacked in this order from the substrate 1 side, 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.

[0043] The high refractive index layer may be made of, for example, a material containing silicon (Si). Examples of the material containing Si include simple Si and Si compounds containing at least one element selected from boron (B), carbon (C), zirconium (Zr), nitrogen (N), and oxygen (O). The use of a high refractive index layer containing Si allows the reflective mask 200 to have excellent reflectivity for EUV light.

[0044] The low refractive index layer may be made of, for example, at least one metal selected from molybdenum (Mo), ruthenium (Ru), rhodium (Rh), and platinum (Pt), or an alloy thereof.

[0045] In the multilayer reflective film coated substrate 110 of this embodiment, it is preferable that the low refractive index layer is a layer containing molybdenum (Mo) and the high refractive index layer is a layer containing silicon (Si). For example, as the multilayer reflective film 5 for reflecting EUV light with a wavelength of 13 nm to 14 nm, a Mo / Si periodic stacked film in which layers containing Mo and layers containing Si are alternately stacked for about 40 to 60 periods is preferably used.

[0046] When the high refractive index layer that is the uppermost layer of the multilayer reflective film 5 is a layer containing silicon (Si), a silicon oxide layer containing silicon and oxygen can be formed between the uppermost layer (Si-containing layer) and the protective film 6. In this case, it is possible to improve the mask cleaning resistance.

[0047] The multilayer reflective coating 5 of this embodiment contains at least one additive element selected from hydrogen (H), deuterium (D), and helium (He). By including at least one additive element selected from hydrogen (H), deuterium (D), and helium (He), the multilayer reflective coating 5 can reduce the roughness of the interfaces between the layers included in the multilayer reflective coating 5 and / or the roughness of the surface of the multilayer reflective coating 5, thereby improving smoothness. This makes it possible to obtain a multilayer reflective coating 5 that has high reflectivity with respect to exposure light and a low background level during defect inspection. As a result, it becomes possible to more accurately detect microdefects (defect signals) present in the multilayer reflective coating coated substrate 110.

[0048] As described above, the multilayer reflective film 5 includes a multilayer film in which low-refractive-index layers and high-refractive-index layers are stacked. At least one additive element selected from hydrogen (H), deuterium (D), and helium (He) may be contained only in the low-refractive-index layer, only in the high-refractive-index layer, or in both layers. However, the effect of reducing the background level during defect inspection is greater when the at least one additive element selected from hydrogen (H), deuterium (D), and helium (He) is contained relatively more in the high-refractive-index layer than in the low-refractive-index layer.

[0049] The present inventors have determined that the atomic density (atom / nm ) of the additive element contained in the multilayer reflective film 5 3 ) and the background level during defect inspection, and the atomic density of the additive element contained in the multilayer reflective film 5 of the multilayer reflective film coated substrate 110 of this embodiment is set to a predetermined range. The atomic density of the additive element contained in the multilayer reflective film 5 of this embodiment is 0.006 atom / nm 3 More than 0.50atom / nm 3 The atomic number density of the added element can be measured by, for example, dynamic SIMS (secondary ion mass spectrometry).

[0050] The atomic density of the additive element contained in the multilayer reflective film 5 is 0.006 atoms / nm 3If the atomic number density of the additive element is less than 0.50 atom / nm, the density of the additive element contained in the multilayer reflective film 5 is too small, and therefore the effect of reducing the roughness of the interfaces of the layers contained in the multilayer reflective film 5 and / or the roughness of the surface of the multilayer reflective film 5 and improving the smoothness cannot be sufficiently obtained. As a result, it becomes impossible to obtain a multilayer reflective film 5 with a sufficiently low background level during defect inspection. On the other hand, if the atomic number density of the additive element is less than 0.50 atom / nm, the effect of reducing the roughness of the interfaces of the layers contained in the multilayer reflective film 5 and / or the surface of the multilayer reflective film 5 and improving the smoothness cannot be sufficiently obtained. 3 If the atomic number density of the additive element contained in the multilayer reflective film 5 is larger than 0.007 atom / nm, the density of the additive element contained in the multilayer reflective film 5 is too large, and the reflectivity of the multilayer reflective film 5 to EUV light decreases. As a result, there is a risk that the contrast of the image of the transfer pattern formed by the reflective mask during exposure may decrease to an unacceptable level. The atomic number density of the additive element contained in the multilayer reflective film 5 is preferably 0.007 atom / nm 3 More preferably, it is 0.008 atom / nm or more. 3 The atomic density of the additive element is preferably 0.10 atom / nm 3 or less, and more preferably 0.07 atom / nm 3 or less, and more preferably 0.04 atom / nm 3 The following is the result.

[0051] By using the multilayer reflective film coated substrate 110 of this embodiment, it is possible to manufacture a reflective mask blank 100 and a reflective mask 200 having a multilayer reflective film 5 that has high reflectivity to exposure light and a low background level during defect inspection. The low background level during defect inspection allows the defect inspection to be performed in a relatively short time, and also makes it possible to more reliably detect actual defects that contribute to transfer.

[0052] Generally, the atomic density (atom / nm) of a certain element can be calculated from only the atomic ratio (at%) of that element. 3 ) of the added element contained in the multilayer reflective film 5. 3) is not directly related to the atomic ratio (at %) of the added element contained in the multilayer reflective film 5. Therefore, even if the atomic ratio (at %) of the added element is described in a known document, the description does not provide any motivation for adjusting the atomic number density of the added element to fall within a predetermined range.

[0053] The multilayer reflective film coated substrate 110 of this embodiment preferably has a background level (BGL) of less than 400 when the surface of the multilayer reflective film 5 is inspected for defects using a defect inspection device. The background level (BGL) when a defect inspection is performed means, for example, a background value observed as signal noise when the surface of the multilayer reflective film 5 is inspected for defects using a blank defect inspection device (ABI: Actinic Blank Inspection) that uses EUV light as the inspection light. In the case of a blank defect inspection device that uses EUV light, the background level (BGL) is automatically calculated based on the measurement signal.

[0054] The reflectivity of the multilayer reflective film 5 of this embodiment alone to EUV light is typically preferably 67% or higher. Since the reflectivity of the multilayer reflective film 5 is 67% or higher, it can be suitably used as a reflective mask 200 for manufacturing semiconductor devices. The upper limit of the reflectivity is typically preferably 73%. The film thicknesses and number of periods (number of pairs) of the low-refractive-index layers and high-refractive-index layers constituting the multilayer reflective film 5 can be appropriately selected depending on the exposure wavelength. Specifically, the film thicknesses and number of periods (number of pairs) of the low-refractive-index layers and high-refractive-index layers constituting the multilayer reflective film 5 can be selected to satisfy the law of Bragg reflection. The multilayer reflective film 5 contains multiple high-refractive-index layers and multiple low-refractive-index layers, but the film thicknesses of the high-refractive-index layers and the low-refractive-index layers do not necessarily have to be the same. The film thickness of the outermost surface (e.g., Si layer) of the multilayer reflective film 5 can be adjusted within a range that does not reduce the reflectivity. The film thickness of the outermost high-refractive-index layer (e.g., Si layer) is, for example, 3 nm to 10 nm.

[0055] In the multilayer reflective film coated substrate 110 of this embodiment, the multilayer reflective film 5 preferably has 30 to 60 periods (pairs), more preferably 35 to 55 periods (pairs), and even more preferably 35 to 45 periods (pairs), with one period (pair) consisting of a pair of a low refractive index layer and a high refractive index layer. The greater the number of periods (pairs), the higher the reflectivity that can be obtained, but the longer the time required to form the multilayer reflective film 5. By setting the period of the multilayer reflective film 5 within an appropriate range, a multilayer reflective film 5 with a relatively high reflectivity can be obtained in a relatively short time.

[0056] The multilayer reflective coating 5 of this embodiment can be formed by ion beam sputtering or magnetron sputtering, such as DC sputtering or RF sputtering. Ion beam sputtering is preferred for forming the multilayer reflective coating 5 because it is less likely to introduce impurities into the multilayer reflective coating 5 and because the ion source is independent and conditions can be set relatively easily. Forming the multilayer reflective coating 5 by ion beam sputtering using a rare gas (e.g., Ar gas, Kr gas, Xe gas) and a gas containing an additive element (e.g., H gas, D gas, He gas) as process gases can result in a multilayer reflective coating 5 containing the additive element. Note that the gas containing the additive element is preferably introduced only when forming the high-refractive-index layer. This allows the formation of a multilayer reflective coating 5 in which the high-refractive-index layer contains a larger amount of the additive element than the low-refractive-index layer.

[0057] The multilayer reflective coating 5 of this embodiment can also be formed using a rare gas as a process gas and a target containing the above-mentioned additive element. By changing the ratio of the additive element contained in the target, the atomic density of the additive element contained in the multilayer reflective coating 5 can be easily adjusted.

[0058] In the multilayer reflective film 5 of this embodiment, the low refractive index layer preferably contains molybdenum (Mo). In this case, the peak intensity of the low refractive index layer containing Mo in X-ray diffraction by an in-plane measurement method preferably satisfies the following formula (1): I (110) / (I(110) +I (200) ) ≦ 0.88 (1) (In equation (1), I (110) indicates the peak intensity of the (110) plane of Mo. (200) indicates the peak intensity of the Mo (200) plane.)

[0059] The peak intensity in X-ray diffraction of the low refractive index layer containing Mo can be measured, for example, using an X-ray diffractometer SmartLab (manufactured by Rigaku Corporation). The measurement conditions can be, for example, the conditions described in the examples below.

[0060] By ensuring that the peak intensity in X-ray diffraction of the low refractive index layer contained in the multilayer reflective film 5 satisfies the above formula (1), it is possible to more reliably manufacture a multilayer reflective film-coated substrate 110 having a multilayer reflective film 5 that has a high reflectivity to exposure light and a low background level during defect inspection.

[0061] <<Protective film 6>> In the multilayer reflective film coated substrate 110 of this embodiment, as shown in Fig. 2, it is preferable to form a protective film 6 on the multilayer reflective film 5. By forming the protective film 6 on the multilayer reflective film 5, it is possible to suppress damage to the surface of the multilayer reflective film 5 when the multilayer reflective film coated substrate 110 is used to manufacture a reflective mask 200. As a result, the resulting reflective mask 200 has good reflectance characteristics for EUV light.

[0062] The protective film 6 can protect the multilayer reflective film 5 from damage caused by dry etching and cleaning in the manufacturing process of the reflective mask 200, which will be described later. The protective film 6 can also protect the multilayer reflective film 5 when repairing opacity defects in the mask pattern using an electron beam (EB).

[0063] FIG. 2 shows a case where the protective film 6 is a single layer. The protective film 6 may have a stacked structure of two layers. Alternatively, the protective film 6 may have a stacked structure of three or more layers. When the protective film 6 has three or more layers, the bottom and top layers may be layers made of a material containing Ru, for example. A layer between the bottom and top layers may be a layer containing a metal other than Ru or an alloy thereof.

[0064] The protective film 6 is formed of, for example, a material containing ruthenium as a main component. Examples of materials containing ruthenium as a main component include simple Ru metal, Ru alloys containing Ru and at least one metal selected from titanium (Ti), niobium (Nb), molybdenum (Mo), zirconium (Zr), yttrium (Y), boron (B), lanthanum (La), cobalt (Co), and rhenium (Re), and materials containing nitrogen in any of these.

[0065] The protective film 6 is preferably formed of a Ru-based material containing Ti. When the multilayer reflective film 5 contains silicon, using a protective film 6 made of a Ru-based material containing Ti can suppress the phenomenon of silicon diffusing from the surface of the multilayer reflective film 5 into the protective film 6. As a result, surface roughness during mask cleaning is reduced, and film peeling is less likely to occur. Reducing surface roughness can prevent a decrease in the reflectivity of the multilayer reflective film 5 for EUV exposure light. Therefore, reducing surface roughness is important for improving the efficiency of EUV exposure and increasing throughput.

[0066] The Ru content of the Ru alloy used for the protective film 6 is 50 atomic % or more and less than 100 atomic %, preferably 80 atomic % or more and less than 100 atomic %, and more preferably 95 atomic % or more and less than 100 atomic %. In particular, when the Ru content of the Ru alloy is 95 atomic % or more and less than 100 atomic %, it is possible to suppress the diffusion of constituent elements (e.g., silicon) of the multilayer reflective film 5 into the protective film 6. In this case, the protective film 6 can ensure sufficient reflectance for EUV light. In this case, the protective film 6 can also improve mask cleaning resistance. Furthermore, the protective film 6 can function as an etching stopper when the absorber film 7 is etched. Furthermore, the protective film 6 can prevent deterioration of the multilayer reflective film 5 over time.

[0067] In EUV lithography, few materials are transparent to the exposure light, making it technically difficult to manufacture a pellicle that prevents foreign particles from adhering to the mask pattern surface. For this reason, pellicle-less operation has become mainstream. Furthermore, EUV lithography can cause exposure contamination, such as the deposition of a carbon film or the growth of an oxide film on the reflective mask 200 due to EUV exposure. Therefore, when the reflective mask 200 is used in semiconductor device manufacturing, it must be frequently cleaned to remove foreign particles and contamination from the reflective mask 200. For this reason, the EUV reflective mask 200 requires significantly higher mask cleaning resistance than transmissive masks used in optical lithography. Using a protective film 6 made of a Ru-based material containing Ti provides particularly high cleaning resistance to cleaning solutions such as sulfuric acid, sulfuric acid hydrogen peroxide (SPM), ammonia, ammonia hydrogen peroxide (APM), OH radical cleaning water, and ozone water with a concentration of 10 ppm or less, thereby satisfying the mask cleaning resistance requirements.

[0068] The thickness of the protective film 6 is not particularly limited as long as it can function as the protective film 6. From the viewpoint of reflectance to EUV light, the thickness of the protective film 6 is preferably 1.0 nm to 8.0 nm, and more preferably 1.5 nm to 6.0 nm.

[0069] Any known film formation method can be used without any particular limitation as the method for forming the protective film 6. Specific examples of the method for forming the protective film 6 include sputtering and ion beam sputtering.

[0070] <Reflective mask blank 100> The following describes the reflective mask blank 100 of this embodiment. By using the reflective mask blank 100 of this embodiment, it is possible to manufacture a reflective mask 200 having a multilayer reflective film 5 that has high reflectivity for exposure light and a low background level during defect inspection.

[0071] <<Absorber membrane 7>> The reflective mask blank 100 has an absorber film 7 on the multilayer reflective film-coated substrate 110 described above. That is, the absorber film 7 is formed on the multilayer reflective film 5 (or on the protective film 6 if the protective film 6 is formed). The basic function of the absorber film 7 is to absorb EUV light. The absorber film 7 may be an absorber film 7 intended for absorbing EUV light, or an absorber film 7 having a phase shift function that takes into account the phase difference of EUV light. An absorber film 7 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 7 having a phase shift function, the absorber film 7 absorbs and attenuates EUV light in the portion where it is formed, while reflecting a portion of the light at a level that does not adversely affect pattern transfer. Furthermore, in the region where the absorber film 7 is not formed (field portion), EUV light is reflected from the multilayer reflective film 5 via the protective film 6. As a result, a desired phase difference is achieved between the light reflected from the absorber film 7, which has a phase shift function, and the light reflected from the field portion. The absorber film 7, which has a phase shift function, is formed so that the phase difference between the light reflected from the absorber film 7 and the light reflected from the multilayer reflective film 5 is 170 to 190 degrees. Light beams with an inverted phase difference of approximately 180 degrees interfere with each other at the pattern edge, improving the image contrast of the projected optical image. This improvement in image contrast leads to increased resolution and makes it possible to increase various exposure latitudes, such as exposure dose latitude and focus latitude.

[0072] The absorber film 7 may be a single-layer film or a multilayer film consisting of multiple films. A single-layer film can reduce the number of steps in mask blank manufacturing, thereby improving production efficiency. A multilayer film can be used, with the upper absorber film functioning as an anti-reflection film during optical mask pattern inspection. In this case, the optical constants and film thickness of the upper absorber film must be appropriately set. This improves the inspection sensitivity during optical mask pattern inspection. Furthermore, the upper absorber film can be doped with oxygen (O) or nitrogen (N), which can improve oxidation resistance. This improves the stability of the absorber film over time. Thus, by using an absorber film 7 consisting of a multilayer film, various functions can be added to the absorber film 7. When the absorber film 7 has a phase shift function, using an absorber film 7 consisting of a multilayer film can expand the range of optical adjustment. This makes it easier to obtain a desired reflectance.

[0073] The material of the absorber film 7 is not particularly limited as long as it has the function of absorbing EUV light and can be processed by etching or the like (preferably by dry etching with a chlorine (Cl) or fluorine (F)-based gas). As a material having such a function, tantalum (Ta) alone or a tantalum compound containing Ta as a main component can be preferably used.

[0074] The absorber film 7 made of the above-mentioned tantalum and tantalum compounds can be formed by magnetron sputtering such as DC sputtering and RF sputtering. For example, the absorber film 7 can be formed by reactive sputtering using a target containing tantalum and boron and argon gas doped with oxygen or nitrogen.

[0075] The tantalum compound for forming the absorber film 7 includes a Ta alloy. When the absorber film 7 is a Ta alloy, the crystalline state of the absorber film 7 is preferably an amorphous or microcrystalline structure in terms of smoothness and flatness. If the surface of the absorber film 7 is not smooth and flat, the edge roughness of the absorber pattern 7a increases, which may result in poor dimensional accuracy of the pattern. The surface roughness of the absorber film 7 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).

[0076] As the tantalum compound for forming the absorber film 7, a compound containing Ta and B, a compound containing Ta and N, a compound containing Ta, O and N, a compound containing Ta and B and further containing at least one of O and N, a compound containing Ta and Si, a compound containing Ta, Si and N, a compound containing Ta and Ge, and a compound containing Ta, Ge and N, etc. can be used.

[0077] Ta has a large absorption coefficient for EUV light. Furthermore, Ta is a material that can be easily dry-etched with chlorine-based gas or fluorine-based gas. Therefore, Ta can be said to be a material for the absorber film 7 that is excellent in processability. Furthermore, by adding B, Si, and / or Ge, etc. to Ta, an amorphous material can be easily obtained. As a result, the smoothness of the absorber film 7 can be improved. Furthermore, by adding N and / or O to Ta, the resistance of the absorber film 7 to oxidation is improved, thereby improving the stability of the absorber film 7 over time.

[0078] In addition to tantalum or a tantalum compound, the material of the absorber film 7 can preferably be 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), 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), or a compound thereof.

[0079] <<Backside conductive film 2>> A backside conductive film 2 for an electrostatic chuck is formed on the second main surface (backside) of the substrate 1 (on the surface opposite the multilayer reflective film 5; or on the intermediate layer if an intermediate layer such as a hydrogen penetration suppression film is formed on the substrate 1). The sheet resistance of the backside conductive film 2 is typically 100 Ω / □ or less. The backside conductive film 2 can be formed, for example, by 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 for forming the backside conductive film 2 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 for forming the backside conductive film 2 is preferably Ta (tantalum), a Ta-containing alloy, or a Ta compound containing any of these and at least one element selected from 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.

[0080] The film thickness of the back surface conductive film 2 is not particularly limited, but is usually 10 nm to 200 nm. The back surface conductive film 2 can adjust the stress on the second main surface side of the mask blank 100. That is, the back surface conductive film 2 can balance the stress generated by various films formed on the first main surface side with the stress on the second main surface side. By balancing the stress on the first main surface side and the second main surface side, the reflective mask blank 100 can be adjusted to be flat.

[0081] Note that, before forming the absorber film 7, a back surface conductive film 2 can be formed on the multilayer reflective film coated substrate 110. In that case, a multilayer reflective film coated substrate 110 having a back surface conductive film 2 as shown in FIG. 2 can be obtained.

[0082] <Other thin films> The multilayer reflective film-coated substrate 110 and the reflective mask blank 100 manufactured by the manufacturing method of this embodiment can include an etching hard mask film (also referred to as an "etching mask film") and / or a resist film 8 on the absorber film 7. Typical materials for the etching hard mask film include silicon (Si) and a material obtained by adding at least one element selected from oxygen (O), nitrogen (N), carbon (C), and hydrogen (H) to silicon, or chromium (Cr) and a material obtained by adding at least one element selected from oxygen (O), nitrogen (N), carbon (C), and hydrogen (H) to chromium. Specific examples include SiO, SiON, SiN, SiO, Si, SiC, SiCO, SiCN, SiCON, Cr, CrN, CrO, CrON, CrC, CrCO, CrCN, and CrOCN. However, when the absorber film 7 is an oxygen-containing compound, it is best to avoid using an oxygen-containing material (e.g., SiO) as the etching hard mask film from the viewpoint of etching resistance. When an etching hard mask film is formed, it becomes possible to reduce the thickness of the resist film 8, which is advantageous for miniaturizing the pattern.

[0083] The multilayer reflective film coated substrate 110 and the reflective mask blank 100 of this embodiment preferably have a hydrogen penetration inhibiting film between the glass substrate serving as the substrate 1 and the back surface conductive film 2 containing tantalum or chromium, the hydrogen penetration inhibiting film inhibiting penetration of hydrogen from the substrate 1 into the back surface conductive film 2. The presence of the hydrogen penetration inhibiting film can inhibit hydrogen from being taken up into the back surface conductive film 2, and can suppress an increase in compressive stress of the back surface conductive film 2.

[0084] The material of the hydrogen penetration inhibiting film may be any type of material that is difficult for hydrogen to permeate and can inhibit hydrogen penetration from the substrate 1 to the back surface conductive film 2. Specific examples of materials for the hydrogen penetration inhibiting film include Si, SiO2, SiON, SiCO, SiCON, SiBO, SiBON, Cr, CrN, CrON, CrC, CrCN, CrCO, CrCON, Mo, MoSi, MoSiN, MoSiO, MoSiCO, MoSiON, MoSiCON, TaO, and TaON. The hydrogen penetration inhibiting film may be a single layer of any of these materials. Alternatively, the hydrogen penetration inhibiting film may be a multi-layer of any of these materials, or may be a compositionally graded film.

[0085] <Reflective mask 200> By patterning the absorber film 7 of the above-mentioned reflective mask blank 100, a reflective mask 200 having an absorber pattern 7a on the multilayer reflective film 5 can be obtained. By using the reflective mask blank 100 of this embodiment, a reflective mask 200 can be obtained that has a multilayer reflective film 5 that has high reflectivity for exposure light and a low background level during defect inspection.

[0086] A reflective mask 200 is manufactured using the reflective mask blank 100 of this embodiment. Only an outline will be given here, and a detailed description will be given later in examples with reference to the drawings.

[0087] A reflective mask blank 100 is prepared, and a resist film 8 is formed on the outermost surface of its first main surface (on top of the absorber film 7, as will be explained in the following examples) (this is not necessary if the reflective mask blank 100 already has a resist film 8). A desired pattern such as a circuit pattern is written (exposed) on this resist film 8, and then developed and rinsed to form a predetermined resist pattern 8a.

[0088] Using this resist pattern 8a as a mask, the absorber film 7 is dry-etched to form the absorber pattern 7a. The etching gas may be selected from the group consisting of chlorine-based gases such as Cl2, SiCl4, and CHCl3; mixed gases containing a chlorine-based gas and O2 at a predetermined ratio; mixed gases containing a chlorine-based gas and He at a predetermined ratio; mixed gases containing a chlorine-based gas and Ar at a predetermined ratio; fluorine-based gases such as CF4, CHF3, C2F6, C3F6, C4F6, C4F8, CH2F2, CH3F, C3F8, SF6, and F2; and mixed gases containing a fluorine-based gas and O2 at a predetermined ratio. If the etching gas contains oxygen in the final etching stage, the surface of the Ru-based protective film 6 will become rough. Therefore, it is preferable to use an etching gas that does not contain oxygen in the over-etching stage, in which the Ru-based protective film 6 is exposed to etching.

[0089] Thereafter, the resist pattern 8a is removed by ashing or using a resist remover solution, to produce an absorber pattern 7a on which a desired circuit pattern is formed.

[0090] Through the above steps, the reflective mask 200 of this embodiment can be obtained.

[0091] <Method of manufacturing a semiconductor device>

[0092] 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.

[0093] In this embodiment, a reflective mask 200 having a multilayer reflective film 5 that has a high reflectivity for exposure light and a low background level during defect inspection can be used for manufacturing semiconductor devices. As a result, the throughput during semiconductor device manufacturing can be improved. Furthermore, since semiconductor devices are manufactured using a reflective mask 200 that has no actual defects on the multilayer reflective film 5 that contribute to transfer, a decrease in the yield of semiconductor devices due to defects in the multilayer reflective film 5 can be suppressed.

[0094] Specifically, a desired transfer pattern can be formed on a semiconductor substrate by EUV exposure using the reflective mask 200 of this embodiment. In addition to this lithography process, various processes such as etching of the film to be processed, formation of insulating films and conductive films, introduction of dopants, and annealing can be carried out to manufacture semiconductor devices with desired electronic circuits formed thereon with high yield. [Example]

[0095] Examples and comparative examples will be described below with reference to the drawings. Note that the same reference numerals are used for similar components in the examples, and descriptions thereof will be simplified or omitted.

[0096] The multilayer reflective film coated substrate 110 of the example includes a substrate 1 and a multilayer reflective film 5, as shown in FIG.

[0097] First, a substrate 1 having a size of 6025 (approximately 152 mm × 152 mm × 6.35 mm) and having a polished first and second main surfaces was prepared. This substrate 1 was made of low-thermal expansion glass (SiO2-TiO2-based glass). The main surfaces of the substrate 1 were polished through a rough polishing process, a precision polishing process, a local polishing process, and a touch polishing process.

[0098] Next, a multilayer reflective film 5 was formed on the main surface (first main surface) of the substrate 1. The multilayer reflective film 5 formed on the substrate 1 was a periodic multilayer reflective film 5 made of Mo and Si to be suitable for EUV light with a wavelength of 13.5 nm. The multilayer reflective film 5 was formed by alternately laminating Mo films and Si films on the substrate 1 by ion beam sputtering using a Mo target and a Si target, a predetermined process gas, and a predetermined target. First, a Si film was formed to a thickness of 4.2 nm, followed by a Mo film to a thickness of 2.8 nm. This constitutes one period, and 40 periods were similarly laminated, and finally, a Si film was formed to a thickness of 4.0 nm to form the multilayer reflective film 5.

[0099] The multilayer reflective coating 5 of this example was formed by adjusting the gas flow rate and / or gas pressure of the process gas so that H, D, or He had a predetermined atomic number density. Tables 1, 2, and 3 show the process gases used when forming the multilayer reflective coatings 5 ​​of the examples and comparative examples. In examples 1 to 6, 9 to 11, and comparative example 2, hydrogen (H) was introduced into the multilayer reflective coating 5 by using H gas in addition to Kr gas when forming the multilayer reflective coating 5. In example 7, deuterium (D) was introduced into the multilayer reflective coating 5 by using D gas in addition to Kr gas when forming the multilayer reflective coating 5. In example 8, helium (He) was introduced into the multilayer reflective coating 5 by using He gas in addition to Kr gas when forming the multilayer reflective coating 5. In comparative example 1, only Kr gas was used when forming the multilayer reflective coating 5.

[0100] <<Atomic number density>> The atomic density (atom / nm ) of the additive element (H, D, or He) contained in the multilayer reflective film 5 of the multilayer reflective film coated substrate 110 obtained in Examples 1 to 11 and Comparative Examples 1 and 2 3 ) were analyzed using a dynamic SIMS (quadrupole secondary ion mass spectrometer: PHI ADEPT-1010 TM The measurement was performed using a Cs ion source (manufactured by ULVAC-PHI, Inc.). + The primary accelerating voltage was 1.0 kV, the primary ion irradiation area was 90 μm square, the secondary ion polarity was positive, and the detected secondary ion species was [Cs-H]+ 、 [Cs-D] + 、 or [Cs-He] + was used. Also, the standard sample was Si. The measurement results are shown in Tables 1, 2, and 3.

[0101] <<Background Level (BGL)>> Defect inspection was performed on the substrates 110 with multilayer reflective films obtained in Examples 1 to 11 and Comparative Examples 1 and 2, and the background level (BGL) of the multilayer reflective film 5 was measured. The background level (BGL) can be automatically measured by a defect inspection device for inspecting defects in the multilayer reflective film 5. As the defect inspection device, an Actinic Blank Inspection device using EUV light as inspection light was used. Tables 1, 2, and 3 show the measurement results of BGL.

[0102] <<Reflectivity>> The reflectivity of the multilayer reflective film 5 of the substrates 110 with multilayer reflective films in Examples 1 to 11 and Comparative Examples 1 and 2 with respect to EUV light with a wavelength of 13.5 nm was measured. Tables 1, 2, and 3 show the measurement results of the reflectivity.

[0103] As shown in Tables 1, 2, and 3, the substrates 110 with multilayer reflective films in Examples 1 to 11, which contain at least one additive element selected from hydrogen (H), deuterium (D), and helium (He) in the multilayer reflective film 5, have a high reflectivity of 67% or more, and the background level during defect inspection is less than 400, and the background level was sufficiently low. On the other hand, the substrate 110 with a multilayer reflective film in Comparative Example 1, which does not contain an additive element in the multilayer reflective film 5, has a high reflectivity of 67% or more, but the background level during defect inspection exceeds 400. Also, the substrate 110 with a multilayer reflective film in Comparative Example 2, which contains a large amount of additive elements, has a background level during defect inspection of less than 400, but the reflectivity is low, less than 67%.

[0104] <<Measurement of X-ray Diffraction Peak Intensity>> X-ray diffraction measurement by in-plane measurement method was performed on the multilayer reflective film 5 of the multilayer reflective film coated substrate 110 obtained in Examples 1 to 8 and Comparative Example 1. Specifically, using an X-ray diffractometer SmartLab (manufactured by Rigaku Corporation), the sample was irradiated with CuKα characteristic X-rays generated at a voltage of 45 kV and a current of 200 mA, and the intensity and diffraction angle (2θ) of the diffracted X-rays were measured to obtain diffraction peaks of the diffracted X-rays corresponding to the (110) plane and the (200) plane of Mo contained in the low refractive index layer. The peak area was measured to obtain the peak intensity I of the Mo (110) plane. (110) , and the peak intensity of the (200) plane I (200) The measurement results were then measured. At that time, the software attached to the measurement device was used to perform processing such as subtracting a predetermined background. Tables 1 and 2 show the measurement results of the peak intensity.

[0105] As shown in Tables 1 and 2, the multilayer reflective film coated substrates 110 of Examples 1 to 8 had a peak intensity I (110) , I (200) But, I (110) / (I (110) +I (200) On the other hand, the multilayer reflective film coated substrate 110 of Comparative Example 1 satisfied the peak intensity I (110) , I (200) But, I (110) / (I (110) +I (200) )=0.891, which did not satisfy the above formula (1).

[0106] In the above-described Examples 1 to 8, the multilayer reflective film 5 is formed of a multilayer film in which Mo and Si are periodically laminated. However, the above-described effects can be obtained even when the multilayer reflective film 5 is formed of a multilayer film containing elements other than Mo and Si. That is, even when the multilayer reflective film 5 is formed of a multilayer film containing elements other than Mo and Si, by including at least one additive element selected from hydrogen (H), deuterium (D), and helium (He), it is possible to obtain a multilayer reflective film-coated substrate 110 having a high reflectance to exposure light and a background level of less than 400 during defect inspection. Furthermore, even when the multilayer reflective film 5 is formed of a multilayer film containing elements other than Mo and Si, ... (110) / (I (110) +I (200) )≦0.88.

[0107] <Reflective mask blank 100> The multilayer reflective film-coated substrates 110 of Examples 1 to 8 and Comparative Example 1 described above have a reflectivity of 67% or more with respect to EUV light having a wavelength of 13.5 nm, which is the exposure light, and thus have a multilayer reflective film 5 with high reflectivity. However, the multilayer reflective film-coated substrate 110 of Comparative Example 1 described above had a high background level of 400 or more during defect inspection, and therefore required a long time for defect inspection. Furthermore, because the background level during defect inspection was high at 400 or more, there was a risk that the multilayer reflective film-coated substrate 110 determined to contain no real defects that would contribute to transfer actually contained real defects. Therefore, the multilayer reflective film coated substrates 110 of Examples 1 to 8, which have high reflectance (67% or more) and low background levels (less than 400), can be used to manufacture the reflective mask blank 100. Hereinafter, a method for manufacturing the reflective mask blank 100 using the multilayer reflective film coated substrates 110 of Examples 1 to 8 will be described.

[0108] A protective film 6 was formed on the surface of the multilayer reflective film coated substrate 110 of Examples 1 to 8. The protective film 6 made of Ru was deposited to a thickness of 2.5 nm by DC sputtering using a Ru target in an Ar gas atmosphere.

[0109] Next, a DC sputtering method was used to form a TaBN film with a thickness of 62 nm as the absorber film 7. The TaBN film was formed by reactive sputtering using a TaB mixed sintered target in a mixed gas atmosphere of Ar gas and N2 gas.

[0110] The elemental ratio of the TaBN film was 75 atomic % Ta, 12 atomic % B, and 13 atomic % N. The refractive index n of the TaBN film at a wavelength of 13.5 nm was approximately 0.949, and the extinction coefficient k was approximately 0.030.

[0111] Next, a back surface conductive film 2 made of CrN was formed on the second main surface (back surface) of the substrate 1 by magnetron sputtering (reactive sputtering) under the following conditions. Conditions for forming the rear surface conductive film 2: Cr target, mixed gas atmosphere of Ar and N2 (Ar: 90 atomic %, N: 10 atomic %), film thickness 20 nm.

[0112] In this manner, a reflective mask blank 100 was manufactured in which the reflectance of the multilayer reflective film 5 was high and the background level during defect inspection of the multilayer reflective film 5 was low.

[0113] <Reflective mask 200> Next, a reflective mask 200 was manufactured using the above-described reflective mask blank 100. A method for manufacturing the reflective mask 200 will be described with reference to FIG.

[0114] First, as shown in FIG. 4(b), a resist film 8 was formed on the absorber film 7 of the reflective mask blank 100. A desired pattern, such as a circuit pattern, was then drawn (exposed) on the resist film 8, and the resist film 8 was then developed and rinsed to form a predetermined resist pattern 8a (FIG. 4(c)). Next, using the resist pattern 8a as a mask, the absorber film 7 (TaBN film) was dry-etched using Cl2 gas to form the absorber pattern 7a (FIG. 4(d)). The protective film 6 made of Ru has extremely high dry etching resistance against Cl2 gas and serves as a sufficient etching stopper. The resist pattern 8a was then removed by ashing or using a resist stripper (FIG. 4(e)).

[0115] <Semiconductor device manufacturing> The reflective mask 200 manufactured as described above was set on an EUV scanner, and a wafer having a processing film and a resist film formed on a semiconductor substrate was subjected to EUV exposure. Then, the exposed resist film was developed to form a resist pattern on the semiconductor substrate having the processing film formed thereon.

[0116] 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.

[0117] [Table 1]

[0118] [Table 2]

[0119] [Table 3] [Explanation of symbols]

[0120] 1 board 2 Backside conductive film 5 Multilayer reflective film 6 Protective film 7. Absorber membrane 7a Absorber pattern 8. Resist film 8a Resist pattern 100 Reflective Mask Blanks 110 Multilayer reflective film substrate 200 Reflective Mask

Claims

1. A multilayer reflective film-coated substrate comprising a substrate and a multilayer reflective film for reflecting exposure light, the multilayer reflective film being made up of a multilayer film in which low refractive index layers and high refractive index layers are alternately laminated on the substrate, the low refractive index layer contains molybdenum (Mo), the high refractive index layer contains silicon (Si), the multilayer reflective film contains hydrogen (H), The atomic density of the hydrogen (H) in the multilayer reflective film is 0.006 atom / nm ３ 0.50 atoms / nm or more ３ A multilayer reflective film-coated substrate characterized by:

2. The atomic density of the hydrogen (H) in the multilayer reflective film is 0.10 atom / nm ３ 2. The multilayer reflective film coated substrate according to claim 1, wherein:

3. 3. The multilayer reflective film coated substrate according to claim 1, further comprising a protective film on the multilayer reflective film.

4. A reflective mask blank comprising an absorber film on the multilayer reflective film of the multilayer reflective film-coated substrate according to claim 1 or 2, or on the protective film of the multilayer reflective film-coated substrate according to claim 3.

5. A reflective mask comprising an absorber pattern formed by patterning the absorber film of the reflective mask blank according to claim 4.

6. 6. A method for manufacturing a semiconductor device, comprising the step of performing a lithography process using an exposure apparatus with the reflective mask according to claim 5 to form a transfer pattern on a transfer target.

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