Substrate with multilayer reflective film, reflective mask blank, reflective mask, and method for manufacturing a 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] This invention relates to a reflective mask used in the manufacture of semiconductor devices, and to a multilayer reflective film-coated substrate and a reflective mask blank used for manufacturing a reflective mask. Furthermore, this invention relates to a method for manufacturing a semiconductor device using the above-mentioned reflective mask. [Background technology]

[0002] In recent years, the semiconductor industry has seen a growing need for finer patterns that exceed the transfer limits of conventional photolithography methods using ultraviolet light, due to the increasing integration of semiconductor devices. To enable the formation of such fine patterns, EUV lithography, an exposure technique using extreme ultraviolet (EUV) light, is considered promising. Here, EUV light refers to light in the wavelength range of the soft X-ray region or vacuum ultraviolet region, specifically light with a wavelength of approximately 0.2 to 100 nm. Reflective masks have been proposed as transfer masks used in EUV lithography. Such reflective masks have a multilayer reflective film that reflects exposure light 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 apparatus 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. As for the multilayer reflective film, for example, a known example is one in which Mo and Si layers with a thickness of several nanometers are alternately stacked to reflect EUV light with a wavelength of 13-14 nm.

[0004] As a technology for manufacturing a multilayer reflective substrate having such a multilayer reflective film, Patent Document 1 describes an integrated extreme ultraviolet blank production system that includes a vacuum chamber for placing the 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 the layers on the multilayer stack deposited as an amorphous metal layer. The amorphous metal layer is described as amorphous molybdenum, and further alloyed with boron, nitrogen, or carbon.

[0005] Patent Document 2 describes a multilayer mirror for soft X-rays and vacuum ultraviolet radiation having a multilayer thin film structure consisting of alternating layers of high-absorption and low-absorption layers for soft X-rays and vacuum ultraviolet radiation, characterized in that the high-absorption layer mainly consists of one or more of the transition metals boride, carbide, silicide, nitride, or oxide, and the low-absorption layer mainly consists of one or more of the elements of carbon, silicon, boron, or beryllium, or compounds thereof.

[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) on which a reflective layer that reflects EUV light is formed on the substrate, wherein the reflective layer is a Mo / Si multilayer reflective film, the Mo / Si multilayer reflective film is formed by sputtering 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 for manufacturing a substrate with a reflective layer for EUVL 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] Japanese Patent Publication No. 2016-519329 [Patent Document 2] Japanese Patent Publication No. 7-97159 [Patent Document 3] Japanese Patent Laid-Open No. 5-297194 [Patent Document 4] Japanese Patent Laid-Open No. 2013-122952 [Summary of the Invention] [Problems to be Solved by the Invention]

[0009] From the perspective of improving the quality of defective products associated with recent pattern miniaturization and the optical properties required for reflective masks (such as the surface reflectivity of multilayer reflective films), 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 substrate with a multilayer reflective film, which is the object of defect inspection, that is, the interfaces of each layer of the multilayer reflective film and / or the surface of the multilayer reflective film, and reducing the 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 substrate with a multilayer reflective film.

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

[0011] In order to increase the reflectance of the multilayer reflective film with respect to the exposure light, it is conceivable to improve the crystallinity of each layer constituting the multilayer reflective film (increase the crystal grain size). However, increasing the crystal grain size causes a problem that the noise (background level: BGL) during defect inspection increases, and the time required for defect inspection increases. This is because when the background level during defect inspection becomes too high, noise is detected as a defect, and it takes a long time to determine real defects that contribute to transfer and pseudo defects that do not contribute to transfer. Also, when the background level during defect inspection becomes high, there is a problem that real defects that contribute to transfer are misjudged as noise and not detected. The reason for the problem of the increase in the background level is considered to be that the crystal particles become coarsened and the smoothness of the interfaces of each layer of the multilayer reflective film and / or the surface of the multilayer reflective film deteriorates. 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 considered to be the cause of the 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 with high reflectance with respect to exposure light and a low background level during defect inspection. Another object of the present invention is to provide a substrate with a multilayer reflective film used for manufacturing a reflective mask blank and a reflective mask having a multilayer reflective film with high reflectance with respect to exposure light and a low background level during defect inspection. Furthermore, an object of the present invention is to provide a method for manufacturing a semiconductor device using the above reflective mask.

[0013] Also, an object of the present invention is to obtain a substrate with a multilayer reflective film, a reflective mask blank, and a reflective mask that can more reliably detect real defects that contribute to transfer.

Means for Solving the Problems

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

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

[0016] (Configuration 2) The atomic number density of the aforementioned additive element in the multilayer reflective film is 0.10 atom / nm. 3 A multilayer reflective substrate according to configuration 1, characterized in that it is as follows.

[0017] (Composition 3) The substrate with a multilayer reflective film according to configuration 1 or 2, characterized in that the aforementioned additive element is deuterium (D).

[0018] (Composition 4) A substrate with a multilayer reflective film according to any one of configurations 1 to 3, characterized in that a protective film is provided on the multilayer reflective film.

[0019] (Composition 5) A reflective mask blank characterized by having an absorbent film on the multilayer reflective film of a substrate with a multilayer reflective film according to any one of configurations 1 to 3, or on the protective film of a substrate with a multilayer reflective film according to configuration 4.

[0020] (Composition 6) A reflective mask characterized by having an absorbent pattern obtained by patterning the absorbent membrane of the reflective mask blank described in configuration 5.

[0021] (Composition 7) A method for manufacturing a semiconductor device, characterized by having a step of performing a lithography process using an exposure apparatus with a reflective mask as described in configuration 6 to form a transfer pattern on a transfer object. [Effects of the Invention]

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

[0023] Furthermore, the present invention provides a multilayer reflective film substrate, a reflective mask blank, and a reflective mask that can more reliably detect actual defects contributing to transfer. [Brief explanation of the drawing]

[0024] [Figure 1] This is a schematic cross-sectional view of an example of a substrate with a multilayer reflective coating. [Figure 2] This is a schematic cross-sectional view of another example of a substrate with a multilayer reflective film. [Figure 3] This is a schematic cross-sectional view of an example of a reflective mask blank. [Figure 4] This is a process diagram showing the manufacturing method of a reflective mask in a schematic cross-sectional view. [Modes for carrying out the invention]

[0025] The embodiments of the present invention will be described in detail below with reference to the drawings. Note that the following embodiments are intended to illustrate the present invention in detail and do not limit the scope of the present invention.

[0026] Figure 1 shows a schematic cross-sectional view of an example of a multilayer reflective substrate 110 according to an embodiment of the present invention. As shown in Figure 1, the multilayer reflective substrate 110 of this embodiment has a multilayer reflective film 5 on a substrate 1. The multilayer reflective film 5 is a film for reflecting exposure light and consists of a multilayer film in which low refractive index layers and high refractive index layers are alternately stacked. The multilayer reflective substrate 110 of 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] Figure 2 shows a schematic cross-sectional view of another example of the multilayer reflective substrate 110 of this embodiment. In the example shown in Figure 2, the multilayer reflective substrate 110 includes a protective film 6.

[0028] A reflective mask blank 100 can be manufactured using the multilayer reflective film substrate 110 of this embodiment. Figure 3 shows a schematic cross-sectional view of an example of a reflective mask blank 100. The reflective mask blank 100 further includes an absorbent 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 protective film 6) of the substrate 110 with a multilayer reflective film. 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, "multilayer reflective film substrate 110" refers to a substrate 1 on which a multilayer reflective film 5 is formed. Figures 1 and 2 show an example of a schematic cross-sectional view of a multilayer reflective film substrate 110. Note that "multilayer reflective film substrate 110" also includes substrates on which thin films other than the multilayer reflective film 5, such as a protective film 6 and / or a back surface conductive film 2, are formed. In this specification, "reflective mask blank 100" refers to a substrate 110 on which an absorber film 7 is formed. Note that "reflective mask blank 100" also includes substrates on which thin films other than the absorber film 7 (for example, an etching mask film and a resist film 8, etc.) are further formed.

[0031] In this specification, "placing (forming) an absorber film 7 on a multilayer reflective film 5" includes not only cases where the absorber film 7 is placed (formed) in contact with the surface of the multilayer reflective film 5, but also cases where another film exists between the multilayer reflective film 5 and the absorber film 7. The same applies to other films. Furthermore, in this specification, for example, "placing film A in contact with the surface of film B" means that film A and film B are placed in direct contact with each other without any other film in between.

[0032] <Multilayer reflective coating substrate 110> The following describes the substrate 1 and each thin film that constitute the multilayer reflective film substrate 110 of this embodiment.

[0033] <<Circuit Board 1>> In the multilayer reflective substrate 110 of this embodiment, it is preferable that the substrate 1 exhibits minimal distortion of the absorber pattern due to heat during EUV exposure. Therefore, it is preferable to use a substrate 1 that has a low thermal expansion coefficient within the range of 0 ± 5 ppb / °C. Examples of materials with a low thermal expansion coefficient within this range include SiO2-TiO2 glass and multi-component glass ceramics.

[0034] The first main surface of the substrate 1 on the side where the transfer pattern (constituted by the absorber film 7 described later) is formed is surface-processed to achieve a predetermined flatness, at least from the viewpoint of obtaining pattern transfer accuracy and positional accuracy. In the case of EUV exposure, the flatness of the 132 mm × 132 mm area of ​​the main surface of the substrate 1 on the side where the transfer pattern is formed is preferably 0.1 μm or less, more preferably 0.05 μm or less, and even more preferably 0.03 μm or less. The second main surface (back side) on the side opposite to where the absorber film 7 is formed is the surface that is electrostatically chucked when set in the exposure apparatus. The second main surface, in a 142 mm × 142 mm area, preferably has a flatness of 0.1 μm or less, more preferably 0.05 μm or less, and even more preferably 0.03 μm or less.

[0035] Furthermore, high 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), and more preferably 0.10 nm or less in Rms. Surface smoothness can be measured using an atomic force microscope.

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

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

[0038] As the material for the conductive undercoat, a material mainly composed of ruthenium or tantalum is preferably used. For example, it may be pure Ru or pure Ta metal, 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). The thickness of the undercoat is preferably in the range of 1 nm to 10 nm.

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

[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, each mainly composed of elements with different refractive indices, are periodically stacked.

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

[0042] The multilayer film used as the multilayer reflective film 5 includes a "high refractive index layer / low refractive index layer" laminated structure in which a high refractive index layer and a low refractive index layer are stacked in that order from the substrate 1 side. One "high refractive index layer / low refractive index layer" constitutes one period, and this laminated structure may be stacked in multiple periods. Alternatively, the multilayer film used as the multilayer reflective film 5 includes a "low refractive index layer / high refractive index layer" laminated structure in which a low refractive index layer and a high refractive index layer are stacked in that order from the substrate 1 side. One "low refractive index layer / high refractive index layer" constitutes one period, and this laminated structure may be stacked in multiple periods. It is preferable that the outermost 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 a high refractive index layer. In the above-described multilayer film, if a high refractive index layer and a low refractive index layer are stacked in that order from the substrate 1 side, the uppermost layer becomes a low refractive index layer. In this case, since the low refractive index layer becomes the outermost surface of the multilayer reflective film 5, the outermost surface of the multilayer reflective film 5 is easily oxidized, and the reflectivity of the reflective mask 200 decreases. Therefore, it is preferable to further form a high refractive index layer on top of the uppermost low refractive index layer. On the other hand, in the above-described multilayer film, if the low refractive index layer and the 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, it is not necessary to form a further high refractive index layer.

[0043] As the high refractive index layer, for example, a material containing silicon (Si) can be used. As the Si-containing material, in addition to elemental Si, a Si compound can be used which contains Si and 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 EUV light reflectivity can be obtained.

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

[0045] In the multilayer reflective 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 multilayer film is preferably used, in which layers containing Mo and layers containing Si are alternately stacked for about 40 to 60 periods.

[0046] Furthermore, if the uppermost layer of the multilayer reflective film 5, which is the high refractive index layer, is a layer containing silicon (Si), a silicon oxide layer containing silicon and oxygen can be formed between the uppermost layer (the Si-containing layer) and the protective film 6. In this case, the mask cleaning resistance can be improved.

[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 including at least one additive element selected from hydrogen (H), deuterium (D), and helium (He) in the multilayer reflective film 5, it becomes possible to reduce the roughness of the interfaces of each layer included in the multilayer reflective film 5 and / or the roughness of the surface of the multilayer reflective film 5, thereby improving the smoothness. As a result, a multilayer reflective film 5 with a high reflectivity to exposure light and a low background level during defect inspection can be obtained. Consequently, it becomes possible to more highly detect minute defects (defect signals) present in the substrate 110 with the multilayer reflective film.

[0048] As described above, the multilayer reflective film 5 includes a multilayer film in which a low refractive index layer and a high refractive index layer are laminated. At least one additive element selected from hydrogen (H), deuterium (D), and helium (He) may be included only in the low refractive index layer, only in the high refractive index layer, or in both of them. However, when 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, the effect of reducing the background level during defect inspection becomes higher.

[0049] The inventor has found that there is a correlation between the atomic number density (atom / nm 3 ) of the above additive element contained in the multilayer reflective film 5 and the background level during defect inspection, and the atomic number density of the additive element contained in the multilayer reflective film 5 of the substrate 110 with the multilayer reflective film of this embodiment is set within a predetermined range. The atomic number density of the above additive element contained in the multilayer reflective film 5 of this embodiment is 0.006 atom / nm 3 or more and 0.50 atom / nm 3 or less. The atomic number density of the additive element can be measured, for example, by dynamic SIMS (secondary ion mass spectrometry).

[0050] When the atomic number density of the additive element contained in the multilayer reflective film 5 is 0.006 atom / nm 3If the atomic number density of the additive elements in the multilayer reflective film 5 is less than 0.50 atom / nm, the effect of reducing the roughness of the interfaces of each layer in the multilayer reflective film 5 and / or the surface roughness of the multilayer reflective film 5 and improving smoothness cannot be sufficiently obtained. As a result, a multilayer reflective film 5 with a sufficiently low background level during defect inspection cannot be obtained. On the other hand, the atomic number density of the additive elements is 0.50 atom / nm. 3 If the atomic number density is greater than this, the density of the additive elements contained in the multilayer reflective film 5 is too high, causing the reflectivity of the multilayer reflective film 5 to EUV light to decrease. As a result, the contrast of the image of the transfer pattern formed by the reflective mask during exposure may decrease to an unacceptable degree. The atomic number density of the above-mentioned additive elements contained in the multilayer reflective film 5 is preferably 0.007 atom / nm. 3 The above is true, and more preferably 0.008 atom / nm 3 That concludes the explanation. Furthermore, the atomic number density of the above-mentioned additive element is preferably 0.10 atom / nm. 3 The following, and more preferably 0.07 atom / nm 3 The following, and more preferably 0.04 atom / nm 3 The following applies:

[0051] By using the multilayer reflective film 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 for relatively quick defect inspection and enables more reliable detection of actual defects that contribute to transfer.

[0052] Generally, it is not possible to determine the atomic number density (atoms / nm) of an element solely from the information of its atomic ratio (at%). 3 It is difficult to calculate the atomic number density (atom / nm) of the above-mentioned additive elements contained in the multilayer reflective film 5. 3The atomic ratio (at%) of the above-mentioned additive elements contained in the multilayer reflective film 5 cannot be directly correlated. Therefore, even if the atomic ratio (at%) of the above-mentioned additive elements is described in a publicly available document, that description does not provide any motivation to adjust the atomic number density of the above-mentioned additive elements to a predetermined range.

[0053] In this embodiment, it is preferable that the background level (BGL) of the substrate 110 with a multilayer reflective film is 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 inspecting for defects refers to the background value observed as noise in the signal when inspecting for defects on the surface of the multilayer reflective film 5 using an Actinic Blank Inspection (ABI) blank defect inspection device 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 reflectance of the multilayer reflective film 5 of this embodiment to EUV light is preferably 67% or higher. A reflectance of 67% or higher allows the multilayer reflective film 5 to be preferably used as a reflective mask 200 for the manufacture of semiconductor devices. The upper limit of the reflectance is preferably 73%. The film thickness and number of periods (pairs) of the low-refractive-index and high-refractive-index layers constituting the multilayer reflective film 5 can be appropriately selected depending on the exposure wavelength. Specifically, the film thickness and number of periods (pairs) of the low-refractive-index and high-refractive-index layers constituting the multilayer reflective film 5 can be selected to satisfy Bragg's law of 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 or the low-refractive-index layers do not necessarily have to be the same. Furthermore, the film thickness of the outermost surface layer (e.g., 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 (e.g., Si layer) is, for example, 3 nm to 10 nm.

[0055] In the substrate 110 with a multilayer reflective film of this embodiment, the multilayer reflective film 5 preferably has 30 to 60 periods (pairs), with one pair of low refractive index layers and high refractive index layers forming one period (pair), more preferably 35 to 55 periods (pairs), and even more preferably 35 to 45 periods (pairs). A higher number of periods (pairs) allows for a higher reflectivity, but the formation time of the multilayer reflective film 5 becomes longer. By setting the period of the multilayer reflective film 5 within an appropriate range, a multilayer reflective film 5 with relatively high reflectivity can be obtained in a relatively short time.

[0056] The multilayer reflective film 5 of this embodiment can be deposited by ion beam sputtering, or by magnetron sputtering methods such as DC sputtering and RF sputtering. It is preferable to deposit the multilayer reflective film 5 by ion beam sputtering because it is less likely for impurities to be mixed into the multilayer reflective film 5, and because the ion source is independent, making condition setting relatively easy. By depositing the multilayer reflective film 5 by ion beam sputtering using a noble gas (Ar gas, Kr gas, Xe gas, etc.) and a gas containing additive elements (H2 gas, D2 gas, He gas, etc.) as process gases, a multilayer reflective film 5 containing the above-mentioned additive elements can be obtained. It is preferable to introduce the gas containing the additive elements only when depositing the high refractive index layer. This makes it possible to deposit a multilayer reflective film 5 that contains more of the above-mentioned additive elements in the high refractive index layer than in the low refractive index layer.

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

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

[0059] The peak intensity in X-ray diffraction of a low refractive index layer containing Mo can be measured, for example, using an X-ray diffractometer such as SmartLab (manufactured by Rigaku Corporation). The measurement conditions can be, for example, those 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 equation (1), it is possible to more reliably manufacture a substrate 110 with a multilayer reflective film 5 that has high reflectivity to exposure light and a low background level during defect inspection.

[0061] <<Protective film 6>> In the multilayer reflective substrate 110 of this embodiment, it is preferable to form a protective film 6 on the multilayer reflective film 5, as shown in Figure 2. By forming the protective film 6 on the multilayer reflective film 5, damage to the surface of the multilayer reflective film 5 when manufacturing the reflective mask 200 using the multilayer reflective substrate 110 can be suppressed. As a result, the reflectivity characteristics of the resulting reflective mask 200 with respect to EUV light are improved.

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

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

[0064] The protective film 6 is formed, for example, from a material mainly composed of ruthenium. Examples of materials mainly composed of ruthenium include elemental Ru metal, Ru alloys containing Ru 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), and materials containing nitrogen.

[0065] The protective film 6 is preferably formed from a Ru-based material containing Ti. When silicon is present in the multilayer reflective film 5, using a protective film 6 made of a Ru-based material containing Ti can suppress the diffusion of silicon from the surface of the multilayer reflective film 5 to the protective film 6. As a result, surface roughness during mask cleaning is reduced, and film peeling is less likely to occur. By reducing surface roughness, a decrease in the reflectivity of the multilayer reflective film 5 to EUV exposure light can be prevented. 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 constituent elements (e.g., silicon) of the multilayer reflective film 5 into the protective film 6. In this case, the protective film 6 can also ensure sufficient reflectivity of EUV light. Furthermore, in this case, the protective film 6 can improve mask cleaning resistance. In addition, the protective film 6 can function as an etching stopper when etching the absorber film 7. Furthermore, the protective film 6 can prevent changes in the multilayer reflective film 5 over time.

[0067] In EUV lithography, there are few materials that are transparent to exposure light, making it technically difficult to manufacture pellicles to prevent foreign matter from adhering to the mask pattern surface. For this reason, pellicle-less operation is the mainstream. In addition, exposure contamination occurs in EUV lithography, such as the deposition of carbon films or the growth of oxide films on the reflective mask 200 due to EUV exposure. For this reason, when the reflective mask 200 is used in the manufacture of semiconductor devices, it is necessary to frequently clean it to remove foreign matter and contamination from the reflective mask 200. For this reason, the EUV reflective mask 200 requires a level of mask cleaning resistance that is orders of magnitude higher than that of transmissive masks used for photolithography. By using a protective film 6 made of a Ru-based material containing Ti, the 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 becomes 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 perform its function as a protective film 6. From the viewpoint of EUV light reflectance, the thickness of the protective film 6 is preferably 1.0 nm to 8.0 nm, more preferably 1.5 nm to 6.0 nm.

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

[0070] <Reflective Mask Blank 100> The reflective mask blank 100 of this embodiment will now be described. 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 to exposure light and low background level during defect inspection.

[0071] <<Absorbing membrane 7>> The reflective mask blank 100 has an absorber film 7 on the substrate 110 with the multilayer reflective film described above. That is, the absorber film 7 is formed on the multilayer reflective film 5 (or on the protective film 6 if a 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 it may be an absorber film 7 having a phase shift function that also 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, in the area where the absorber film 7 is formed, it absorbs EUV light to reduce its brightness while reflecting some of the light at a level that does not adversely affect pattern transfer. Also, in the area where the absorber film 7 is not formed (field area), EUV light is reflected from the multilayer reflective film 5 via the protective film 6. Therefore, 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 section. The absorber film 7, which has a phase-shift function, is formed such that the phase difference between the light reflected from the absorber film 7 and the light reflected from the multilayer reflective film 5 is between 170 and 190 degrees. The light with inverted phase differences near 180 degrees interferes with each other at the pattern edge, improving the image contrast of the projected optical image. This improvement in image contrast increases the resolution, and various exposure-related margins such as exposure margin and focus margin can be increased.

[0072] The absorber film 7 may be a single layer or a multilayer film consisting of multiple layers. In the case of a single layer, the number of steps in mask blank manufacturing can be reduced, thus improving production efficiency. In the case of a multilayer film, the upper absorber film can function as an anti-reflective film during mask pattern inspection using light. In this case, it is necessary to appropriately set the optical constants and film thickness of the upper absorber film. This improves the inspection sensitivity during mask pattern inspection using light. Furthermore, a film to which oxygen (O) and nitrogen (N), etc., which can improve oxidation resistance can be added, can be used as the upper absorber film. This improves the stability of the absorber film over time. In this way, by using a multilayer absorber film 7, it is possible to add various functions to the absorber film 7. If the absorber film 7 has a phase shift function, the range of adjustment on the optical surface can be greatly increased by using a multilayer absorber film 7. This makes it easier to obtain the desired reflectance.

[0073] The material for 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 (preferably etchable by dry etching with chlorine (Cl) or fluorine (F) gases). As such a material, tantalum (Ta) alone or a tantalum compound containing Ta as the main component can be preferably used.

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

[0075] The tantalum compound for forming the absorber film 7 includes an alloy of Ta. When the absorber film 7 is an alloy of Ta, the crystalline state of the absorber film 7 is preferably amorphous or microcrystalline 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 will increase, and the dimensional accuracy of the pattern may deteriorate. The preferred surface roughness of the absorber film 7 is 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 membrane 7, compounds containing Ta and B, compounds containing Ta and N, compounds containing Ta, O and N, compounds containing Ta and B and further containing at least one of O and N, compounds containing Ta and Si, compounds containing Ta, Si and N, compounds containing Ta and Ge, and compounds containing Ta, Ge and N, etc., can be used.

[0077] Ta has a high absorption coefficient for EUV light. Furthermore, Ta is a material that can be easily dry-etched with chlorine-based or fluorine-based gases. Therefore, Ta can be considered a material for absorber films 7 with excellent processability. Moreover, by adding B, Si, and / or Ge to Ta, amorphous materials can be easily obtained. As a result, the smoothness of the absorber film 7 can be improved. Additionally, by adding N and / or O to Ta, the resistance of the absorber film 7 to oxidation is improved, thereby enhancing the long-term stability of the absorber film 7.

[0078] In addition, as the material for the absorber membrane 7, in addition to tantalum or tantalum compounds, 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 compounds thereof, can preferably be used.

[0079] <<Back surface conductive film 2>> A back surface conductive film 2 for an 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; 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 back surface conductive film 2 is usually 100 Ω / □ or less. The back surface 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 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 Cr compounds include CrN, CrON, CrCN, CrCON, CrBN, CrBON, CrBCN, and CrBOCN. The tantalum (Ta)-containing material for forming the back surface conductive film 2 is preferably Ta (tantalum), a Ta-containing alloy, or a Ta compound containing at least one selected from boron, nitrogen, oxygen, and carbon in any of these. 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 between 10 nm and 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 the 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 and second main surface sides, the reflective mask blank 100 can be adjusted to be flat.

[0081] Furthermore, the back surface conductive film 2 can be formed on the multilayer reflective substrate 110 before forming the absorber film 7 described above. In that case, a multilayer reflective substrate 110 with a back surface conductive film 2 as shown in Figure 2 can be obtained.

[0082] <Other thin films> The multilayer reflective film substrate 110 and reflective mask blank 100 manufactured by the manufacturing method of this embodiment may be provided with an etching hard mask film (also called 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 materials to which at least one element selected from oxygen (O), nitrogen (N), carbon (C), and hydrogen (H) has been added to silicon, or chromium (Cr), and materials to which at least one element selected from oxygen (O), nitrogen (N), carbon (C), and hydrogen (H) has been added to chromium. Specifically, examples include SiO2, SiON, SiN, SiO, Si, SiC, SiCO, SiCN, SiCON, Cr, CrN, CrO, CrON, CrC, CrCO, CrCN, and CrOCN. However, if the absorber film 7 is a compound containing oxygen, materials containing oxygen (e.g., SiO2) should be avoided as the etching hard mask film from the viewpoint of etching resistance. When a hard mask film for etching is formed, the thickness of the resist film 8 can be reduced, which is advantageous for miniaturizing the pattern.

[0083] In this embodiment, the multilayer reflective substrate 110 and the reflective mask blank 100 preferably include a hydrogen intrusion suppression film between the glass substrate 1 and the back surface conductive film 2 containing tantalum or chromium, which suppresses the intrusion of hydrogen from the substrate 1 into the back surface conductive film 2. The presence of the hydrogen intrusion suppression film can suppress the incorporation of hydrogen into the back surface conductive film 2, thereby suppressing an increase in the compressive stress of the back surface conductive film 2.

[0084] The material for the hydrogen intrusion-inhibiting film can be any type of material that is impermeable to hydrogen and can suppress the intrusion of hydrogen from the substrate 1 to the back conductive film 2. Specific examples of materials for the hydrogen intrusion-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 intrusion-inhibiting film may be a single layer of these materials. Alternatively, the hydrogen intrusion-inhibiting film may be multiple layers of these materials, or it may be a film with a compositional gradient.

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

[0086] A reflective mask 200 is manufactured using the reflective mask blank 100 of this embodiment. Only an overview is provided here; a detailed explanation will follow later in the examples section 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) (this step is unnecessary if the reflective mask blank 100 already has a resist film 8). A desired pattern, such as a circuit pattern, is drawn (exposed) onto this resist film 8, and then developed and rinsed to form a predetermined resist pattern 8a.

[0088] The absorber pattern 7a is formed by dry etching the absorber film 7 using this resist pattern 8a as a mask. The etching gas can be selected from chlorine-based gases such as Cl2, SiCl4, and CHCl3, a mixed gas containing chlorine-based gas and O2 in a predetermined ratio, a mixed gas containing chlorine-based gas and He in a predetermined ratio, a mixed gas containing chlorine-based gas and Ar in a predetermined ratio, fluorine-based gases such as CF4, CHF3, C2F6, C3F6, C4F6, C4F8, CH2F2, CH3F, C3F8, SF6, F2, and a mixed gas containing fluorine-based gas and O2 in a predetermined ratio. If oxygen is present in the etching gas at the final stage of etching, surface roughness will occur on the Ru-based protective film 6. For this reason, it is preferable to use an etching gas that does not contain oxygen in the over-etching stage when the Ru-based protective film 6 is exposed to etching.

[0089] Subsequently, the resist pattern 8a is removed using ashing or a resist stripping solution to create an absorber pattern 7a with the desired circuit pattern.

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

[0091] <Manufacturing method for semiconductor devices>

[0092] The semiconductor device manufacturing method of this embodiment includes a step of forming a transfer pattern on a transfer object by performing a lithography process using an exposure apparatus with the reflective mask 200 described above.

[0093] In this embodiment, a reflective mask 200 having a multilayer reflective film 5 with high reflectivity to exposure light and low background level during defect inspection can be used for the manufacture of semiconductor devices. As a result, the throughput during the manufacture of semiconductor devices can be improved. Furthermore, since the semiconductor device is manufactured using a reflective mask 200 that does not have actual defects on the multilayer reflective film 5 that contribute to transfer, a decrease in the yield of semiconductor devices caused by defects in the multilayer reflective film 5 can be suppressed.

[0094] Specifically, by performing EUV exposure using the reflective mask 200 of this embodiment, a desired transfer pattern can be formed on a semiconductor substrate. In addition to this lithography process, various other processes such as etching the workpiece, forming insulating films and conductive films, introducing dopants, and annealing can be performed to manufacture semiconductor devices with a high yield in which the desired electronic circuits are formed. [Examples]

[0095] The following describes examples and comparative examples with reference to the drawings. In the examples, the same reference numerals are used for similar components, and their descriptions are simplified or omitted.

[0096] As shown in Figure 1, the multilayer reflective film substrate 110 of the embodiment has a substrate 1 and a multilayer reflective film 5.

[0097] First, a 6025 size (approximately 152 mm x 152 mm x 6.35 mm) substrate 1 was prepared, with its first and second main surfaces polished. This substrate 1 is made of low thermal expansion glass (SiO2-TiO2 glass). The main surface of substrate 1 was polished by 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. To make the multilayer reflective film 5 formed on the substrate 1 suitable for EUV light with a wavelength of 13.5 nm, a periodic multilayer reflective film 5 made of Mo and Si was formed. The multilayer reflective film 5 was formed by alternately stacking Mo films and Si films on the substrate 1 using an ion beam sputtering method with a predetermined process gas and predetermined targets, using a Mo target and a Si target. First, a Si film was deposited to a thickness of 4.2 nm, followed by a Mo film to a thickness of 2.8 nm. This constituted one period, and 40 periods were stacked in the same manner, and finally a Si film to a thickness of 4.0 nm was deposited to form the multilayer reflective film 5.

[0099] The multilayer reflective film 5 in this embodiment was deposited 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 depositing the multilayer reflective film 5 in the examples and comparative examples. In Examples 1-6, 9-11, and Comparative Example 2, hydrogen (H2) was introduced into the multilayer reflective film 5 by using H2 gas in addition to Kr gas during the deposition of the multilayer reflective film 5. In Example 7, deuterium (D2) was introduced into the multilayer reflective film 5 by using D2 gas in addition to Kr gas during the deposition of the multilayer reflective film 5. In Example 8, helium (He) was introduced into the multilayer reflective film 5 by using He gas in addition to Kr gas during the deposition of the multilayer reflective film 5. In Comparative Example 1, only Kr gas was used when depositing the multilayer reflective film 5.

[0100] <<Atomic number density>> The atomic number density (atom / nm) of the additive elements (H, D, or He) contained in the multilayer reflective film 5 of the multilayer reflective film substrate 110 obtained in Examples 1 to 11 and Comparative Examples 1 and 2. 3 ) is a dynamic SIMS (quadrupole secondary ion mass spectrometer: PHI ADEPT-1010) TM The measurement was performed using a device manufactured by ULVAC-PHI, Inc. The measurement conditions were as follows: the primary ion species was Cs + The primary acceleration voltage is 1.0kV, the primary ion irradiation area is 90μm square, the secondary ion polarity is positive, and the detected secondary ion species is [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] <<Reflectance>> The reflectance 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 reflectance.

[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 reflectance of 67% or more, and the background level during defect inspection is less than 400, and the background level is 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 reflectance 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 an additive element, has a background level during defect inspection of less than 400, but the reflectance is low at less than 67%.

[0104] <<Measurement of X-ray Diffraction Peak Intensity>> X-ray diffraction measurements were performed on the multilayer reflective film 5 of the multilayer reflective film substrate 110 obtained in Examples 1-8 and Comparative Example 1 using the in-plane measurement method. Specifically, using an X-ray diffractometer SmartLab (manufactured by Rigaku Corporation), characteristic X-rays of CuKα generated by a voltage of 45kV and a current of 200mA were irradiated onto the sample, and the intensity and diffraction angle (2θ) of the diffracted X-rays were measured to obtain the diffraction peaks of the diffracted X-rays corresponding to the (110) plane and (200) plane of Mo contained in the low refractive index layer. By measuring the area of ​​the peaks, the peak intensity I of the (110) plane of Mo was determined. (110) , and the peak intensity of the (200) plane I (200) The peak intensity was measured. During this process, the software attached to the measuring device was used to subtract a predetermined background level. Tables 1 and 2 show the measurement results for the peak intensity.

[0105] As shown in Tables 1 and 2, the multilayer reflective film substrates 110 of Examples 1 to 8 have a peak intensity of I (110) , I (200) However, I (110) / ( I (110) +I (200) The condition ) ≤ 0.88 was satisfied. On the other hand, the multilayer reflective film substrate 110 of Comparative Example 1 had a peak intensity of I (110) , I (200) However, I (110) / ( I (110) +I (200) ) = 0.891, which did not satisfy equation (1) above.

[0106] In the above-described Examples 1 to 8, the multilayer reflective film 5 was shown to be a multilayer film in which Mo and Si are periodically stacked. However, even if the multilayer reflective film 5 is a multilayer film containing elements other than Mo and Si, the above effects can be obtained. That is, even if the multilayer reflective film 5 is 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), a substrate 110 with a multilayer reflective film that has high reflectivity to exposure light and a background level of less than 400 during defect inspection can be obtained. Furthermore, even if the multilayer reflective film 5 is a multilayer film containing elements other than Mo and Si, the peak intensity ratio in X-ray diffraction of Mo contained in the low refractive index layer is I (110) / ( I (110) +I (200) A substrate 110 with a multilayer reflective film that satisfies ) ≤ 0.88 can be obtained.

[0107] <Reflective Mask Blank 100> The multilayer reflective film substrates 110 of Examples 1-8 and Comparative Example 1 have a reflectivity of 67% or more to EUV light with a wavelength of 13.5 nm, which is the exposure light, and possess a highly reflective multilayer reflective film 5. However, the multilayer reflective film substrate 110 of Comparative Example 1 had a high background level of 400 or more during defect inspection, resulting in a long inspection time. Furthermore, because the background level during defect inspection is high (400 or more), there is a risk that the multilayer reflective film substrate 110 that was determined to be free of actual defects contributing to transfer may actually contain actual defects. Therefore, a reflective mask blank 100 can be manufactured using the multilayer reflective film substrate 110 of Examples 1 to 8, which has a high reflectivity (67% or more) and a low background level (less than 400). The manufacturing method of the reflective mask blank 100 using the multilayer reflective film substrate 110 of Examples 1 to 8 will be described below.

[0108] A protective film 6 was formed on the surface of the multilayer reflective film 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 TaBN film with a thickness of 62 nm was formed as the absorber film 7 by DC sputtering. The TaBN film was formed using a TaB mixed sintering target in a mixed gas atmosphere of Ar gas and N2 gas by reactive sputtering.

[0110] The elemental ratio of the TaBN film was 75 atomic percent Ta, 12 atomic percent B, and 13 atomic percent 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 substrate 1 by magnetron sputtering (reactive sputtering) under the following conditions. Formation conditions for 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] As described above, a reflective mask blank 100 was manufactured in which the reflectivity 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 reflective mask blank 100 described above. The manufacturing method of the reflective mask 200 will be explained with reference to Figure 4.

[0114] First, as shown in Figure 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) onto this resist film 8, and a predetermined resist pattern 8a was formed by developing and rinsing (Figure 4(c)). Next, using the resist pattern 8a as a mask, the absorber film 7 (TaBN film) was dry-etched with Cl2 gas to form an absorber pattern 7a (Figure 4(d)). The protective film 6 made of Ru has extremely high resistance to dry etching with Cl2 gas and serves as a sufficient etching stopper. After that, the resist pattern 8a was removed by ashing or a resist stripping solution (Figure 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 on which the workpiece film and resist film had been formed on the semiconductor substrate. Then, by developing this exposed resist film, a resist pattern was formed on the semiconductor substrate on which the workpiece film had been formed.

[0116] By transferring this resist pattern to the workpiece through etching, and then going through various processes such as forming insulating films and conductive films, introducing dopants, or annealing, we were able to manufacture semiconductor devices with desired properties with a high yield.

[0117] [Table 1]

[0118] [Table 2]

[0119] [Table 3] [Explanation of Symbols]

[0120] 1 circuit board 2. Conductive film on the back surface 5 Multilayer reflective film 6 Protective film 7 Absorbent membrane 7a Absorber pattern 8. Resist film 8a Resist Pattern 100 Reflective Mask Blanks 110 Multilayer reflective substrate 200 Reflective Masks

Claims

1. A substrate with a multilayer reflective film, comprising a substrate and a multilayer reflective film for reflecting exposure light, which is made of a multilayer film in which low refractive index layers and high refractive index layers are alternately stacked on the substrate, The aforementioned multilayer reflective film contains hydrogen (H), The low refractive index layer contains molybdenum (Mo), The aforementioned high refractive index layer contains silicon (Si), The peak intensity in X-ray diffraction of the aforementioned multilayer reflective film by in-plane measurement is 0.694 ≤ I （１１０） / (I （１１０） +I （２００） ) ≤ 0.88, I （１１０） This shows the peak intensity of the (110) plane of Mo, and I （２００） A multilayer reflective substrate characterized by exhibiting peak intensity on the (200) plane of Mo.

2. The substrate with a multilayer reflective film according to Claim 1, characterized in that the atomic number density of hydrogen (H) in the multilayer reflective film is 0.50 atoms / nm³ or less.

3. The substrate with a multilayer reflective film according to claim 1 or 2, characterized in that a protective film is provided on the multilayer reflective film.

4. A reflective mask blank characterized by having an absorbent film on the multilayer reflective film of the multilayer reflective film substrate according to claim 1 or 2, or on the protective film of the multilayer reflective film substrate according to claim 3.

5. A reflective mask characterized by comprising an absorbent pattern obtained by patterning the absorbent membrane of the reflective mask blank described in claim 4.

6. A method for manufacturing a semiconductor device, characterized by comprising the step of performing a lithography process using an exposure apparatus with a reflective mask as described in claim 5 to form a transfer pattern on a transfer object.

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