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

Abstract

To provide a substrate with a multilayer reflective film, used for manufacturing a reflective mask blank and a reflective mask each having a multilayer reflective film having a high reflectance to exposure light and a low background level during defect inspection.SOLUTION: A substrate with a multilayer reflective film 110 comprises a substrate 1 and a multilayer reflective film 5. The multilayer reflective film 5 is formed of a multilayer film in which a low refractive index layer and a high refractive index layer are alternately layered on the substrate 1. The multilayer reflective film 5 comprises at least one additive element selected from hydrogen (H), deuterium (D), and helium (He). The additive element in the multilayer reflective film 5 has an atomic number density of 0.006 atom / nm3 or more and 0.50 atom / nm3 or less.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a reflective mask used in the manufacture of a semiconductor device, a multilayer reflective film-coated substrate and a reflective mask blank used for the manufacture of a reflective mask, and a method for manufacturing a semiconductor device using the reflective mask. [Background technology]

[0002] In recent years, in the semiconductor industry, with the increasing integration of semiconductor devices, fine patterns exceeding the transfer limit of conventional photolithography using ultraviolet light are required. To enable the formation of such fine patterns, EUV lithography, which is an exposure technology using extreme ultraviolet (hereinafter referred to as "EUV") light, is considered promising. Here, EUV light refers to light in a wavelength band in the soft X-ray region or the vacuum ultraviolet region, specifically light with a wavelength of about 0.2 to 100 nm. A reflective mask has been proposed as a transfer mask used in this EUV lithography. In such a reflective mask, a multilayer reflective film that reflects exposure light is formed on a substrate, and an absorber film that absorbs exposure light is 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 the multilayer reflective film in areas without the absorber film. The reflected image is transferred onto a semiconductor substrate through a reflective optical system to form a mask pattern. As the multilayer reflective film, for example, one in which Mo and Si are alternately stacked to a thickness of several nm to reflect EUV light having a wavelength of 13 to 14 nm is known.

[0004] As a technique for manufacturing a substrate with 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. As the amorphous metal layer, it is described that amorphous molybdenum is further alloyed with boron, nitrogen, or carbon.

[0005] Patent Document 2 describes a multilayer film reflector for soft X-rays and vacuum ultraviolet light having a multilayer thin film structure consisting of alternating layers of high absorption layers and low absorption layers for soft X-rays and vacuum ultraviolet light, characterized in that the high absorption layers have one or more of transition metal borides, carbides, silicides, nitrides and oxides as a main component, and the low absorption layers have 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 includes forming a reflective layer that reflects EUV light on a substrate, the reflective layer being 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 (H2), 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 miniaturization of patterns and the optical properties (such as the surface reflectance of the multilayer reflective film) required of a reflective mask, 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 that is the subject 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] In addition, 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 portion of the multilayer reflective film. In order to obtain a high contrast during exposure, it is desirable for the multilayer reflective film to have a high reflectance with respect to the exposure light.

[0011] In order to increase the reflectance of the multilayer reflective film to the exposure light, it is possible to improve the crystallinity of each layer constituting the multilayer reflective film (to increase the crystal grain size). However, when the crystal grain size is increased, the noise (background level: BGL) during defect inspection increases, which causes a problem of increasing the time required for defect inspection. This is because, if the background level during defect inspection becomes too high, the noise is detected as a defect, and it takes a long time to determine whether the real defect that contributes to the transfer is a pseudo defect that does not contribute to the transfer. In addition, when the background level during defect inspection becomes high, the real defect that contributes to the transfer is erroneously determined as noise and is not detected. The reason for the problem of the high background level is thought to be that the crystal grains become coarse, which deteriorates the smoothness of the interfaces of each layer of the multilayer reflective film and / or the surface of the multilayer reflective film. The deterioration of the smoothness of the interfaces of each layer of the multilayer reflective film and / or the surface of the multilayer reflective film 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 are capable of more reliably detecting 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 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 in that:

[0016] (Configuration 2) The atomic density of the additive element in the multilayer reflective film is 0.10 atom / nm 3 2. 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. Effect 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.The present invention can also 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 description of the drawings]

[0024] [Figure 1] FIG. 2 is a schematic cross-sectional view of an example of a multilayer reflective film-coated substrate. [Diagram 2] FIG. 2 is a schematic cross-sectional view of another example of a multilayer reflective film-coated substrate. [Diagram 3] FIG. 2 is a schematic cross-sectional view of an example of a reflective mask blank. [Figure 4] 1A to 1C are schematic cross-sectional views illustrating steps of a method for manufacturing a reflective mask. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that the following embodiments are merely for the purpose of specifically describing the present invention, and are not intended to limit the scope of the present invention.

[0026] Fig. 1 shows a schematic cross-sectional view 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 laminated. 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 shows 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 one 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 reflectance to EUV light can be obtained.

[0030] In this specification, the term "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 the multilayer reflective film-coated substrate 110. The term "multilayer reflective film-coated substrate 110" includes substrates 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, the term "reflective mask blank 100" refers to a substrate having a multilayer reflective film-coated substrate 110 on which an absorber film 7 is formed. The term "reflective mask blank 100" includes substrates having a thin film other than the absorber film 7 (such as an etching mask film and a resist film 8) further formed thereon.

[0031] In this specification, "the absorber film 7 is disposed (formed) on the multilayer reflective film 5" includes not only the case where the absorber film 7 is disposed (formed) in contact with the surface of the multilayer reflective film 5, but also 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, "film A is disposed 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, without another film being 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] <<Substrate 1>> The substrate 1 in the multilayer reflective film coated substrate 110 of this embodiment is preferably one in which the distortion of the absorber pattern due to heat during EUV exposure is small. For this reason, 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 the transfer pattern (constituting the absorber film 7 described later) is formed is surface-processed to have a predetermined flatness from the viewpoint of obtaining 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 on which the transfer pattern of the substrate 1 is formed. In addition, the second main surface (rear surface) on the opposite side to the side on which the absorber film 7 is formed is a surface that is electrostatically chucked when set in an exposure device. 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 of ​​the second main surface.

[0035] In addition, 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 by an atomic force microscope.

[0036] Furthermore, the substrate 1 preferably has high rigidity in order 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 undercoat film 3 in contact with the surface of the substrate 1. The undercoat film 3 is a thin film formed between the substrate 1 and the multilayer reflective film 5. The undercoat film 3 may be a film having a function according to the purpose. For example, the undercoat film 3 may be a conductive layer that prevents charge-up during mask pattern defect inspection using an electron beam. The undercoat film 3 may be a planarizing layer that improves the planarization of the surface of the substrate 1. The undercoat film 3 may be a smoothing layer that improves the planarization of the surface of the substrate 1.

[0038] As the material of the undercoat film having the above-mentioned conductive function, a material containing ruthenium or tantalum as a main component is preferably used. For example, it may be Ru metal alone or Ta metal alone, or it may be a Ru alloy or Ta alloy containing 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) in addition to Ru or Ta. The thickness of the undercoat film is preferably in the range of, for example, 1 nm to 10 nm.

[0039] As the material of the undercoat film for improving the flatness and smoothness, silicon or a material containing silicon as a main component is preferably used. The material of the undercoat film may be, for example, silicon (Si) alone, or SiO2 or SiO3, which contains oxygen (O) and nitrogen (N) in Si. x(x<2), SiON, Si3N4, Si x N y (x: 3, y: natural number other than 4) may be used. As in the above, the thickness of the undercoat film is preferably in the range of, for example, 1 nm to 10 nm.

[0040] <<Multilayer reflective film 5>> The multilayer reflective film 5 provides the reflective mask 200 with a 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 laminated.

[0041] Generally, the multilayer reflective film 5 is a multilayer film in which thin films (high refractive index layers) of a light element or its compound, which is a high refractive index material, and thin films (low refractive index layers) of a heavy element or its compound, which is a low refractive index material, are alternately stacked in about 40 to 60 periods (pairs).

[0042] The multilayer film used as the multilayer reflective film 5 includes a laminated structure of "high refractive index layer / low refractive index layer" in which a high refractive index layer and a low refractive index layer are laminated in this order from the substrate 1 side. This laminated structure may be laminated multiple times, with one "high refractive index layer / low refractive index layer" being one period. Alternatively, the multilayer film used as the multilayer reflective film 5 includes a laminated structure of "low refractive index layer / high refractive index layer" in which a low refractive index layer and a high refractive index layer are laminated in this order from the substrate 1 side. This laminated structure may be laminated multiple times, with one "low refractive index layer / high refractive index layer" being one period. Note that the top layer of the multilayer reflective film 5, that is, the surface layer of the multilayer reflective film 5 on the side opposite to the substrate 1 side, is preferably a high refractive index layer. In the above-mentioned multilayer film, when a high refractive index layer and a low refractive index layer are laminated in this order from the substrate 1 side, the top layer becomes a low refractive index layer. In this case, since the low refractive index layer becomes the top surface of the multilayer reflective film 5, the top surface of the multilayer reflective film 5 is easily oxidized, and the reflectance of the reflective mask 200 decreases. Therefore, it is preferable to further form a high refractive index layer on the uppermost low refractive index layer. On the other hand, in the above-mentioned multilayer film, when a low refractive index layer and a high refractive index layer are laminated in this order from the substrate 1 side, the uppermost layer becomes a high refractive index layer. Therefore, in this case, it is not necessary to form an additional high refractive index layer.

[0043] For example, a material containing silicon (Si) can be used as the high refractive index layer. In addition to simple Si, the material containing Si can be a Si compound containing at least one element selected from boron (B), carbon (C), zirconium (Zr), nitrogen (N) and oxygen (O). By using a high refractive index layer containing Si, a reflective mask 200 with excellent reflectance to EUV light can be obtained.

[0044] For the low refractive index layer, for example, at least one metal selected from molybdenum (Mo), ruthenium (Ru), rhodium (Rh), and platinum (Pt), or an alloy of these metals can be used.

[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 laminated film in which layers containing Mo and layers containing Si are alternately laminated 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 film 5 of this embodiment contains at least one additive element selected from hydrogen (H), deuterium (D), and helium (He). By containing at least one additive element selected from hydrogen (H), deuterium (D), and helium (He), the multilayer reflective film 5 can reduce the roughness of the interfaces between the layers contained in the multilayer reflective film 5 and / or the roughness of the surface of the multilayer reflective film 5, thereby improving the smoothness. This makes it possible to obtain a multilayer reflective film 5 that has a high reflectance to the 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 film-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, may be contained only in the high-refractive index layer, or may be contained in both layers. However, the effect of reducing the background level during defect inspection is higher 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 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 density of the added element can be measured, for example, by dynamic SIMS (secondary ion mass spectrometry).

[0050] The atomic density of the additive element contained in the multilayer reflective film 5 is 0.006 atom / nm 3If the atomic 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 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. Therefore, it is not possible to obtain a multilayer reflective film 5 with a sufficiently low background level during defect inspection. On the other hand, if the atomic density of the additive element is less than 0.50 atom / nm 3 If the atomic 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 reflectance of the multilayer reflective film 5 to EUV light decreases. As a result, the contrast of the image of the transfer pattern formed by the reflective mask during exposure may decrease to an unacceptable level. The atomic 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 3 The atomic density of the additive element is preferably 0.10 atom / nm 3 More preferably, it is 0.07 atom / nm or less. 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 a high reflectance to exposure light and a low background level during defect inspection. Since the background level during defect inspection is low, the defect inspection can be performed in a relatively short time, and real defects that contribute to transfer can be detected more reliably.

[0052] Generally, the atomic density (atom / nm) of an element can be calculated from only the atomic ratio (at%) of that element. 3 It is difficult to calculate the atomic density (atom / nm ) of the additive 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 a motivation for adjusting the atomic density of the added element to a predetermined range.

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

[0054] The reflectance of the multilayer reflective film 5 alone of this embodiment to EUV light is preferably 67% or more. Since the reflectance of the multilayer reflective film 5 is 67% or more, it can be preferably used as a reflective mask 200 for manufacturing a semiconductor device. The upper limit of the reflectance is preferably 73%. The film thickness and the number of periods (number of pairs) of the low refractive index layer and the high refractive index layer constituting the multilayer reflective film 5 can be appropriately selected depending on the exposure wavelength. Specifically, the film thickness and the number of periods (number of pairs) of the low refractive index layer and the high refractive index layer constituting the multilayer reflective film 5 can be selected so as to satisfy the law of Bragg reflection. In the multilayer reflective film 5, there are multiple high refractive index layers and multiple low refractive index layers, but the film thicknesses of the high refractive index layers and the film thicknesses of the low refractive index layers do not necessarily have to be the same. In addition, the film thickness of the outermost surface (for example, Si layer) of the multilayer reflective film 5 can be adjusted within a range that does not reduce the reflectance. The film thickness of the outermost high refractive index layer (for example, 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 pair of a low refractive index layer and a high refractive index layer as one period (pair). The greater the number of periods (pairs), the higher the reflectance 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 in an appropriate range, a multilayer reflective film 5 with a relatively high reflectance can be obtained in a relatively short time.

[0056] The multilayer reflective film 5 of this embodiment can be formed by ion beam sputtering or magnetron sputtering such as DC sputtering and RF sputtering. It is preferable to form the multilayer reflective film 5 by ion beam sputtering because impurities are unlikely to be mixed into the multilayer reflective film 5, the ion source is independent, and the conditions can be relatively easily set. When the multilayer reflective film 5 is formed by ion beam sputtering using a rare gas (Ar gas, Kr gas, Xe gas, etc.) and a gas containing an additive element (H2 gas, D2 gas, He gas, etc.) as process gas, the multilayer reflective film 5 containing the additive element can be obtained. It is preferable to introduce the gas containing the additive element only when forming the high refractive index layer. This makes it possible to form a multilayer reflective film 5 containing the additive element in a larger amount in the high refractive index layer than in the low refractive index layer.

[0057] The multilayer reflective film 5 of the present embodiment can also be formed by 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 film 5 can be easily adjusted.

[0058] In the multilayer reflective film 5 of the present embodiment, the low refractive index layer preferably contains molybdenum (Mo). In this case, the peak intensity in X-ray diffraction by an in-plane measurement method of the low refractive index layer containing Mo preferably satisfies the following formula (1). I (110) / (I(110) +I (200) ) ≦ 0.88 (1) (In formula (1), I (110) indicates the peak intensity of the Mo (110) plane. (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, by using an X-ray diffraction device SmartLab (manufactured by Rigaku Corp.) The measurement conditions can be, for example, the conditions described in the examples below.

[0060] When 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 reflectance to the 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, a protective film 6 is preferably formed on the multilayer reflective film 5. By forming the protective film 6 on the multilayer reflective film 5, damage to the surface of the multilayer reflective film 5 can be suppressed 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 described later. The protective film 6 can also protect the multilayer reflective film 5 when repairing black defects in a 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 laminated structure of two layers. Or, the protective film 6 may have a laminated structure of three or more layers. When the protective film 6 has three or more layers, the bottom layer and the top layer may be layers made of a material containing Ru, for example. The layer between the bottom layer and the top layer 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 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 these alloys.

[0065] The protective film 6 is preferably made of a Ru-based material containing Ti. When the multilayer reflective film 5 contains silicon, the phenomenon of silicon diffusing from the surface of the multilayer reflective film 5 to the protective film 6 can be suppressed by using the protective film 6 made of a Ru-based material containing Ti. As a result, surface roughness during mask cleaning is reduced, and film peeling is less likely to occur. Reducing the surface roughness can prevent a decrease in the reflectance 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 in 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 the constituent elements (e.g., silicon) of the multilayer reflective film 5 to the protective film 6. In this case, the protective film 6 can ensure a sufficient reflectance of EUV light. In this case, the protective film 6 can improve the mask cleaning resistance. Furthermore, the protective film 6 can function as an etching stopper when etching the absorber film 7. Furthermore, the protective film 6 can prevent the multilayer reflective film 5 from changing over time.

[0067] In EUV lithography, since there are few materials transparent to the exposure light, it is technically not easy to manufacture a pellicle that prevents foreign matter from adhering to the mask pattern surface. For this reason, pellicle-less operation that does not use a pellicle has become mainstream. In addition, in EUV lithography, exposure contamination occurs, such as the deposition of a carbon film on the reflective mask 200 and the growth of an oxide film due to EUV exposure. For this reason, when the reflective mask 200 is used in the manufacture of a semiconductor device, it is necessary to frequently clean the reflective mask 200 to remove foreign matter and contamination on the reflective mask 200. For this reason, the EUV reflective mask 200 is required to have a mask cleaning resistance that is orders of magnitude higher than that of a transmission mask for optical lithography. If the protective film 6 made of a Ru-based material containing Ti is used, the cleaning resistance against 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 is particularly high, making it possible to meet the requirements for mask cleaning resistance.

[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 the reflectance of 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 a sputtering method and an ion beam sputtering method.

[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 a high reflectance to 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 (on the protective film 6 when 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 to absorb EUV light, or an absorber film 7 having a phase shift function that takes into account the phase difference of EUV light. The absorber film 7 having a phase shift function absorbs EUV light and reflects a part of it to shift the phase. That is, in the reflective mask 200 in which the absorber film 7 having a phase shift function is patterned, the absorber film 7 absorbs and attenuates EUV light in the part where the absorber film 7 is formed, while reflecting a part of the light at a level that does not adversely affect pattern transfer. In addition, in the region (field portion) in which the absorber film 7 is not formed, the EUV light is reflected from the multilayer reflective film 5 via the protective film 6. Therefore, there is a desired phase difference between the reflected light from the absorber film 7 having a phase shift function and the reflected light from the field portion. The absorber film 7 having a phase shift function is formed so that the phase difference between the reflected light from the absorber film 7 and the reflected light from the multilayer reflective film 5 is 170 degrees to 190 degrees. Light beams with an inverted phase difference of about 180 degrees interfere with each other at the pattern edge portion, thereby improving the image contrast of the projected optical image. With the improvement in image contrast, the resolution increases, and various exposure tolerances such as exposure dose tolerance and focus tolerance can be increased.

[0072] The absorber film 7 may be a single-layer film or a multi-layer film made of a plurality of films. In the case of a single-layer film, the number of steps in manufacturing a mask blank can be reduced, improving production efficiency. In the case of a multi-layer film, the upper absorber film can function as an anti-reflection film during mask pattern inspection using light. In this case, the optical constant and film thickness of the upper absorber film need to be appropriately set. This improves the inspection sensitivity during mask pattern inspection using light. In addition, a film to which oxygen (O) and nitrogen (N) that can improve oxidation resistance are added can be used as the upper absorber film. This improves the stability of the absorber film over time. In this way, by using the absorber film 7 made of a multi-layer film, it becomes possible to add various functions to the absorber film 7. When the absorber film 7 has a phase shift function, the range of adjustment on the optical surface can be increased by using the absorber film 7 made of a multi-layer film. 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 of the above-mentioned tantalum and tantalum compound can be formed by magnetron sputtering such as DC sputtering and RF sputtering. For example, the absorber film 7 can be formed by a reactive sputtering method using a target containing tantalum and boron and argon gas to which oxygen or nitrogen is added.

[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, and the dimensional accuracy of the pattern may deteriorate. 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 terms of 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. In addition, 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 has excellent 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, and therefore the stability over time of the absorber film 7 can be improved.

[0078] As the material for the absorber film 7, in addition to tantalum or a tantalum compound, 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, can be preferably used.

[0079] <<Backside conductive film 2>> A back surface conductive film 2 for electrostatic chuck is formed on the second main surface (back surface) of the substrate 1 (on the surface opposite to the multilayer reflective film 5. If an intermediate layer such as a hydrogen penetration suppression film is formed on the substrate 1, on the intermediate layer). The sheet resistance of the back surface conductive film 2 is usually 100Ω / □ or less. The back surface conductive film 2 can be formed by magnetron sputtering or ion beam sputtering using a target of a metal such as chromium or tantalum, or an alloy thereof. The material containing chromium (Cr) for forming the back surface conductive film 2 is preferably a Cr compound containing Cr and at least one selected from boron, nitrogen, oxygen, and carbon. Examples of the Cr compound include CrN, CrON, CrCN, CrCON, CrBN, CrBON, CrBCN, and CrBOCN. The material containing tantalum (Ta) for forming the back surface conductive film 2 is preferably Ta (tantalum), an alloy containing Ta, or a Ta compound containing any of these and at least one 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 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 caused by various films formed on the first main surface side and 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 above-mentioned absorber film 7, a back surface conductive film 2 can be formed on the multilayer reflective film-coated substrate 110. In that case, it is possible to obtain a multilayer reflective film-coated substrate 110 having the back surface conductive film 2 as shown in FIG.

[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 have an etching hard mask film (also called an "etching mask film") and / or a resist film 8 on the absorber film 7. Representative 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 SiO2, SiON, SiN, SiO, Si, SiC, SiCO, SiCN, SiCON, Cr, CrN, CrO, CrON, CrC, CrCO, CrCN, and CrOCN. However, when the absorber film 7 is a compound containing oxygen, it is better to avoid using a material containing oxygen (e.g., SiO2) as the etching hard mask film from the viewpoint of etching resistance. When a hard mask film for etching 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 suppression film between the glass substrate, which is the substrate 1, and the back surface conductive film 2 containing tantalum or chromium, for suppressing penetration of hydrogen from the substrate 1 into the back surface conductive film 2. The presence of the hydrogen penetration suppression film can suppress the incorporation of hydrogen into the back surface conductive film 2, and can suppress an increase in the compressive stress of the back surface conductive film 2.

[0084] The material of the hydrogen penetration suppression film may be any type of material that is difficult for hydrogen to permeate and can suppress the penetration of hydrogen from the substrate 1 to the back surface conductive film 2. Specific examples of the material of the hydrogen penetration suppression 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 suppression film may be a single layer of these materials. Alternatively, the hydrogen penetration suppression film may be a multiple layer of these materials, or a composition gradient film.

[0085] <Reflection mask 200> A reflective mask 200 having an absorber pattern 7a on the multilayer reflective film 5 can be obtained by patterning the absorber film 7 of the above-mentioned reflective mask blank 100. By using the reflective mask blank 100 of this embodiment, a reflective mask 200 can be obtained having a multilayer reflective film 5 that has a high reflectance to 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 described in the following examples) (not necessary if the reflective mask blank 100 is provided with a resist film 8). A desired pattern such as a circuit pattern is drawn (exposed) on this resist film 8, and then developed and rinsed to form a predetermined resist pattern 8a.

[0088] The absorber film 7 is dry-etched using the resist pattern 8a as a mask to form the absorber pattern 7a. The etching gas may be selected from chlorine-based gases such as Cl2, SiCl4, and CHCl3, mixed gases containing chlorine-based gas and O2 at a predetermined ratio, mixed gases containing chlorine-based gas and He at a predetermined ratio, mixed gases containing 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 fluorine-based gas and O2 at a predetermined ratio. If oxygen is contained in the etching gas at the final stage of etching, the surface of the Ru-based protective film 6 will become rough. For this reason, it is preferable to use an etching gas that does not contain oxygen at the overetching 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 stripper, 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 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-mentioned reflective mask 200 to form a transfer pattern on a transfer target object.

[0093] In this embodiment, a reflective mask 200 having a multilayer reflective film 5 with high reflectance to exposure light and low background level during defect inspection can be used for manufacturing a semiconductor device. As a result, the throughput during manufacturing of the semiconductor device can be improved. Furthermore, since a semiconductor device is manufactured using a reflective mask 200 with no real defects on the multilayer reflective film 5 that contribute to transfer, a decrease in the yield of the semiconductor device caused by 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 an insulating film or a conductive film, introduction of a dopant, and annealing can be carried out to manufacture a semiconductor device having a desired electronic circuit formed thereon with a high yield. EXAMPLES

[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] A multilayer reflective film coated substrate 110 of the embodiment 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) with a first main surface and a second main surface polished was prepared. This substrate 1 is a substrate 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 localized 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 in order to make the multilayer reflective film 5 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 an ion beam sputtering method using a Mo target and a Si target and a predetermined process gas and a predetermined target. First, a Si film was formed to a thickness of 4.2 nm, and then a Mo film was formed to a thickness of 2.8 nm. This constitutes one period, and 40 periods were laminated in the same manner, 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 film 5 of this embodiment 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 density. Tables 1, 2 and 3 show the process gases used when forming the multilayer reflective film 5 of the embodiments and comparative examples. In embodiments 1 to 6, 9 to 11 and comparative example 2, hydrogen (H2) was introduced to the multilayer reflective film 5 by using H2 gas in addition to Kr gas when forming the multilayer reflective film 5. In embodiment 7, deuterium (D2) was introduced to the multilayer reflective film 5 by using D2 gas in addition to Kr gas when forming the multilayer reflective film 5. In embodiment 8, helium (He) was introduced to the multilayer reflective film 5 by using He gas in addition to Kr gas when forming the multilayer reflective film 5. In comparative example 1, only Kr gas was used when forming the multilayer reflective film 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 ) using a dynamic SIMS (quadrupole secondary ion mass spectrometer: PHI ADEPT-1010 TM The measurement was performed using a 1000-mV ion ion detector (ULVAC-PHI, Inc.). The measurement conditions were as follows: Cs + The primary acceleration 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 apparatus for inspecting defects in the multilayer reflective film 5. As the defect inspection apparatus, an Actinic Blank Inspection apparatus 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 having 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, in which the multilayer reflective film 5 contains at least one additive element selected from hydrogen (H), deuterium (D), and helium (He), had a high reflectivity of 67% or more, and the background level during defect inspection was 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, in which the multilayer reflective film 5 does not contain an additive element, had a high reflectivity of 67% or more, but the background level during defect inspection exceeded 400. Also, the substrate 110 with a multilayer reflective film in Comparative Example 2, which contains a large amount of additive element, had a background level during defect inspection of less than 400, but the reflectivity was low, less than 67%.

[0104] <<Measurement of X-ray Diffraction Peak Intensity>> X-ray diffraction measurement was performed by an in-plane measurement method 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, an X-ray diffraction device SmartLab (manufactured by Rigaku Corporation) was used to irradiate the sample with characteristic X-rays of CuKα 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) and (200) planes of Mo contained in the low refractive index layer. The peak area was measured to obtain the peak intensity I (110) , and the peak intensity of the (200) plane I (200) The results were measured. At that time, the software attached to the measuring 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-mentioned Examples 1 to 8, the multilayer reflective film 5 is a multilayer film in which Mo and Si are periodically laminated. However, even if the multilayer reflective film 5 is a multilayer film containing elements other than Mo and Si, the above-mentioned effects can be obtained. That is, even if the multilayer reflective film 5 is a multilayer film containing elements other than Mo and Si, 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 by including at least one additive element selected from hydrogen (H), deuterium (D), and helium (He). Also, even if the multilayer reflective film 5 is a multilayer film containing elements other than Mo and Si, 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 if the multilayer reflective film 5 is a multilayer film containing elements other than Mo and Si, 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. (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 reflectance 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 reflectance. 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. In addition, since the background level during defect inspection was high at 400 or more, there is a risk that the multilayer reflective film-coated substrate 110 determined to contain no real defects that contribute to transfer may contain real defects. Therefore, the multilayer reflective film coated substrate 110 of Examples 1 to 8, which has a high reflectance (67% or more) and a low background level (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 substrate 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 having 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 back 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 having a multilayer reflective film 5 with high reflectance and a low background level during defect inspection of the multilayer reflective film 5 was manufactured.

[0113] <Reflection mask 200> Next, a reflective mask 200 was manufactured using the above-mentioned 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. Then, a desired pattern such as a circuit pattern was drawn (exposed) on the resist film 8, and the resist film 8 was developed and rinsed to form a predetermined resist pattern 8a (FIG. 4(c)). Next, the absorber film 7 (TaBN film) was dry-etched using Cl2 gas with the resist pattern 8a as a mask to form an 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. After that, the resist pattern 8a was removed by ashing or using a resist stripper (FIG. 4(e)).

[0115] <Manufacturing of semiconductor devices> The reflective mask 200 manufactured as described above was set in an EUV scanner, and EUV exposure was performed on a wafer having a film to be processed and a resist film formed on a semiconductor substrate. Then, a resist pattern was formed on the semiconductor substrate having the film to be processed by developing the exposed resist film.

[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, making it possible to manufacture semiconductor devices with the desired characteristics 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 blank 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 multilayer reflective film contains at least one additive element selected from hydrogen (H), deuterium (D), and helium (He); the low refractive index layer contains molybdenum (Mo), The peak intensity of the multilayer reflective film in an X-ray diffraction measurement by an in-plane measurement method satisfies I (110) / (I (110) +I (200) )≦0.88; A multilayer reflective film-coated substrate, wherein I(110) represents the peak intensity of the Mo (110) plane, and I(200) represents the peak intensity of the Mo (200) plane.

2. A substrate with a multilayer reflective film as described in claim 1, characterized in that the high refractive index layer contains silicon (Si).

3. 3. The multilayer reflective film coated substrate according to claim 1, wherein the additional element is deuterium (D).

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

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 claims 1 to 3, or on the protective film of the multilayer reflective film-coated substrate according to claim 4.

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

7. 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 claim 6 to form a transfer pattern on a transfer target.

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