Mask blank, reflective mask, and method for producing semiconductor device

Abstract

The present invention provides a mask blank capable of producing a reflective mask that exhibits excellent transfer characteristics when photolithography is performed with an EUV exposure device. The mask blank is one in which a multilayer reflective film and a thin film for pattern formation are installed in this order on the main surface of a substrate. The thin film is made of a metal-containing material, and when the refractive index of the thin film for light with wavelength λL = 13.2 nm is nL, the refractive index of the thin film for light with wavelength λM = 13.5 nm is nM, the refractive index of the thin film for light with wavelength λH = 13.8 nm is nH, and the coefficient P = [(1-nH) / λH-(1-nL) / λL] / [(1-nM) / λM], the absolute value of the coefficient P is 0.09 or less.

Description

Technology Field

[0001] The present invention relates to a mask blank, which is a plate for manufacturing an exposure mask used in the manufacture of semiconductor devices, a reflective mask, and a method for manufacturing a semiconductor device. Background Technology

[0002] Photolithography equipment used in the manufacture of semiconductor devices has evolved by gradually shortening the wavelength of the light source. To realize finer pattern transfer, EUV lithography using extreme ultraviolet light (EUV; sometimes referred to as EUV light) with a wavelength of around 13.5 nm has been developed. In EUV lithography, reflective masks are used because there are few materials that are transparent to EUV light. Representative reflective masks include reflective binary masks and reflective phase shift masks (reflective halftone phase shift masks).

[0003] Technologies related to such reflective masks for EUV lithography and mask blanks for producing them are described in Patent Documents 1 and 2.

[0004] Patent Document 1 discloses a mask for extreme ultraviolet exposure comprising a high-reflection portion formed by a multilayer film formed on a substrate and a low-reflection portion formed by a single layer film formed on a part of the multilayer film. In this mask, the reflected light from the low-reflection portion has a reflectance of 5 to 15% with respect to the reflected light from the high-reflection portion and has a phase difference of 175 to 185 degrees with respect to the reflected light from the high-reflection portion, and the refractive index (1-δ) and decay coefficient β of the single layer film constituting the low-reflection portion with respect to the exposure wavelength are characterized in that they are within the region connecting a predetermined point coordinate (1-δ, β) in a planar coordinate system in which the refractive index (1-δ) and decay coefficient β are the coordinate axes.

[0005] Patent Document 2 discloses a reflective mask blank having, on a substrate, a multilayer reflective film, a protective film, and a phase shift film that shifts the phase of EUV light in this order. This reflective mask blank is characterized in that the reflectance of the surface of the phase shift film is greater than 3% and less than or equal to 20%, and the phase shift film is composed of a material made of an alloy having two or more types of metals, wherein a group of metal elements satisfying k > α*n + β, a refractive index n, and a decay coefficient k is designated as Group A, and a group of metal elements satisfying k < α*n + β, a refractive index n, and a decay coefficient k is designated as Group B, wherein the alloy is composed of one or more metal elements selected from each of Group A and Group B, and the composition ratio is adjusted such that when the film thickness of the phase shift film varies by ±0.5% relative to the set film thickness, the change in the phase difference is within the range of ±2 degrees and the change in reflectance is within the range of ±0.2%. (wherein α: proportionality constant, β: constant.) Prior art literature

[0006] Japanese Patent Publication No. 2006-228766 and Japanese Patent Publication No. 2018-146945 The problem to be solved

[0007] As patterns become finer and the precision of pattern dimensions and positioning increases, the electrical characteristics and performance of semiconductor devices improve, and integration density can be enhanced and chip size reduced. For this reason, EUV lithography requires high-precision and fine-dimensional pattern transfer performance that is one step higher than conventional methods. Currently, there is a demand for ultra-fine and high-precision pattern formation corresponding to the hp 16 nm (half pitch 16 nm) generation. To meet these demands, a reflective mask that utilizes EUV light as an exposure light and a phase-shift effect is required.

[0008] In a reflective mask utilizing such a phase shift effect, at the center wavelength of EUV light, 13.5 nm, a multilayer reflective film is installed on the main surface of a substrate, and a thin film for pattern formation (e.g., an absorber film) installed on the multilayer reflective film is designed to have a phase shift effect.

[0009] In the case of reflective masks, further improvement in exposure transfer characteristics is required. In particular, in the case of a reflective mask having a thin film (e.g., an absorber pattern) having a transfer pattern formed using a phase shift effect, further improvement in the optical properties of this thin film is required.

[0010] Therefore, the present invention aims to provide a mask blank capable of producing a reflective mask that exhibits excellent transfer characteristics when photolithography is performed with an EUV exposure device.

[0011] In addition, the present invention aims to provide a reflective mask capable of exhibiting excellent transfer characteristics when photolithography is performed with an EUV exposure device, and to provide a method for manufacturing a semiconductor device using the reflective mask. means of solving the problem

[0012] To solve the above problem, the present invention has the following configuration.

[0013] (Composition 1)

[0014] A mask blank having a multilayer reflective film and a pattern-forming thin film installed in this order on the main surface of a substrate,

[0015] The above thin film is made of a material containing metal, and

[0016] Wavelength λ of the above thin film L n = the refractive index for light of 13.2 nm L ,

[0017] Wavelength λ of the above thin film M= refractive index for light of 13.5 nm is n M ,

[0018] Wavelength λ of the above thin film H = refractive index for light of 13.8 nm, n H ,

[0019] Coefficient P = [(1-n H ) / λ H -(1-n L ) / λ L ] / [(1-n M ) / λ M When saying ]

[0020] A mask blank characterized in that the absolute value of the coefficient P is 0.09 or less.

[0021] (Composition 2)

[0022] Wavelength λ M The refractive index n of the above thin film with respect to light M A mask blank described in Composition 1, characterized by having a value of 0.96 or less.

[0023] (Composition 3)

[0024] A mask blank described in configuration 1 or 2, characterized in that the thickness of the thin film is less than 100 nm.

[0025] (Composition 4)

[0026] A mask blank described in any one of configurations 1 to 3, characterized by having a protective film between the multilayer reflective film and the thin film.

[0027] (Composition 5)

[0028] The above thin film is, the wavelength λ M A mask blank described in any one of configurations 1 to 4, characterized by generating a phase difference of 130 to 230 degrees between the reflected light from the thin film and the reflected light from the multilayer reflective film with respect to the light.

[0029] (Composition 6)

[0030] A reflective mask in which a multilayer reflective film and a thin film having a transfer pattern formed thereon are installed in this order on the main surface of a substrate,

[0031] The above thin film is made of a material containing metal, and

[0032] Wavelength λ of the above thin film L n = the refractive index for light of 13.2 nm L ,

[0033] Wavelength λ of the above thin film M = refractive index for light of 13.5 nm is n M ,

[0034] Wavelength λ of the above thin film H = refractive index for light of 13.8 nm, n H ,

[0035] Coefficient P = [(1-n H ) / λ H -(1-n L ) / λ L ] / [(1-n M ) / λ M When saying ]

[0036] A reflective mask characterized in that the absolute value of the coefficient P is 0.09 or less.

[0037] (Composition 7)

[0038] Wavelength λ M The refractive index n of the above thin film with respect to light M A reflective mask described in configuration 6, characterized by having a value of 0.96 or less.

[0039] (Composition 8)

[0040] A reflective mask described in configuration 6 or 7, characterized in that the thickness of the thin film is less than 100 nm.

[0041] (Composition 9)

[0042] A reflective mask described in any one of configurations 6 to 8, characterized by having a protective film between the multilayer reflective film and the thin film.

[0043] (Composition 10)

[0044] The above thin film is, the wavelength λ M A reflective mask described in any one of configurations 6 to 9, characterized by generating a phase difference of 130 to 230 degrees between the reflected light from the thin film and the reflected light from the multilayer reflective film with respect to light.

[0045] (Composition 11)

[0046] A method for manufacturing a semiconductor device characterized by using a reflective mask described in any one of configurations 6 to 10 and having a process of photolithographically transferring the transfer pattern onto a resist film on a semiconductor substrate. Effects of the invention

[0047] According to the present invention, a mask blank can be provided that can produce a reflective mask capable of exhibiting excellent transfer characteristics when photolithography is performed with an EUV exposure device.

[0048] In addition, according to the present invention, it is possible to provide a reflective mask capable of exhibiting excellent transfer characteristics when photolithography is performed with an EUV exposure device, a method for manufacturing the same, and a method for manufacturing a semiconductor device using the reflective mask. Brief explanation of the drawing

[0049] FIG. 1 is a schematic cross-sectional view of a main part to explain an example of the schematic configuration of a reflective mask blank of an embodiment of the present invention. FIG. 2 is a schematic cross-sectional view of a major part to explain an example of the schematic configuration of a reflective mask from a reflective mask blank. FIG. 3 is a graph showing the relationship between the reflectance on a multilayer reflective film and the wavelength when EUV light is used as an exposure light in a reflective mask blank of an embodiment of the present invention. Specific details for implementing the invention

[0050] Hereinafter, embodiments of the present invention will be described, but first, the circumstances leading to the present invention will be explained. The inventors have conducted extensive research on means capable of exhibiting excellent transfer characteristics when performing photolithography transfer with an EUV exposure apparatus.

[0051] The inventors believed that by considering wavelength ranges other than the center wavelength of EUV light when selecting the material of the absorber film constituting the thin film for pattern formation, the optical properties of the absorber pattern of the reflective mask can be improved. This is explained using FIG. 3. FIG. 3 is a graph showing the relationship between the reflectance on a multilayer reflective film and the wavelength when EUV light is used as the exposure light in a reflective mask blank of an embodiment of the present invention. As can be seen from the figure, the EUV light incident on the multilayer reflective film in the EUV exposure apparatus has a certain amplitude not only at the center wavelength of 13.5 nm but also in the wavelength range near it. As shown in the figure, the multilayer reflective film has a high reflectance of over 70% at the center wavelength of 13.5 nm, but also has a reflectance that cannot be ignored in the wavelength range near it. For example, in the wavelength range of 13.0 nm to 14.0 nm, it has a reflectance of more than 10%, and in the wavelength range of 13.2 nm to 13.8 nm, it has a reflectance of more than 30%.

[0052] The refractive index n of the film material changes depending on the wavelength of the exposure light. Meanwhile, in the case of a reflective mask, the phase difference φ between the EUV light reflected from the multilayer reflective film and the EUV light reflected from the absorber film can be calculated using the following relationship (1) using the wavelength λ of the light, the refractive index n at that wavelength λ, and the film thickness d (since it is a reflective type, the optical path difference becomes 2d).

[0053] Phase difference φ between EUV light reflected from the multilayer reflective film and EUV light reflected from the absorber film:

[0054] 2π(1-n)×2d / λ=4π(1-n)d / λ… (1)

[0055] It is speculated that the phase difference φ is enhanced as it approaches the same value at each wavelength of the EUV light with a wavelength band (as the deviation Δφ of the phase difference φ at each wavelength of the EUV light with a wavelength band becomes smaller).

[0056] In the above-described equation (1), the film thickness d is constrained from the perspective of optical properties. For this reason, attention was paid to the part of 4π(1-n) / λ excluding the film thickness d in the above-described equation (1).

[0057] As a result of the review, wavelength λ L = 13.2 nm, λ M = 13.5 nm, λ H n = 13.8 nm, where n is the angular refractive index of the thin film for each light. L , n M , n H Let it be, and coefficient A L = 4π×(1-n L ) / λ L , A M = 4π×(1-n M ) / λ M , A H = 4π×(1-n H ) / λ H , coefficient P=(A H -A L ) / A M Assuming that the thin film satisfies the condition |P|≤0.09, when photolithography is performed using an EUV exposure device, the wavelength band λ of the EUV light L = 13.2 nm ~ λ H Phase difference φ at 13.8 nm L ~φ H The deviation Δφ(=φ H -φ LIt was concluded that the magnitude of the (hereinafter referred to simply as "phase difference Δφ") can be suppressed to 20 degrees or less, and excellent transfer characteristics can be exhibited. Here, the coefficient P can be developed as follows.

[0058] Coefficient P = (A H -A L ) / A M

[0059] =[(1-n H ) / λ H -(1-n L ) / λ L ] / [(1-n M ) / λ M ]

[0060] The present invention was made as a result of examining the examples described above. Furthermore, the method for deriving the coefficient P described above does not limit the scope of the rights of the present invention (coefficient A L , A M , A H (is not an essential element of the present invention).

[0061] In this embodiment, the center wavelength λ of the EUV light M Phase difference φ in M It is designed so that this is approximately 1.2π (approximately 216 degrees). This is because, due to the occurrence of double diffraction caused by a reflective optical system, or the influence of the absorber pattern and multilayer film, the effective reflective surface is located further toward the substrate than the interface between the absorber film and the multilayer reflective film. However, the present invention is not limited to this, and for example, the central wavelength λ of EUV light M Phase difference φ in M It is also possible to apply this to thin films for pattern formation designed to be π (180 degrees). Phase difference φ M In the case where this is set to π (180 degrees), the wavelength band of EUV light (λ L ~λ HIn ), by making the absolute value of the coefficient P 0.09 or less, the phase difference Δφ(=φ H -φ L The size of ) can be suppressed to 17 degrees or less.

[0062] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Furthermore, the following embodiments are merely forms for embodying the present invention and do not limit the scope of the present invention. Additionally, in the drawings, identical or equivalent parts are denoted by the same reference numerals, and their descriptions may be simplified or omitted.

[0063] <Composition of reflective mask blank (100) and method of manufacturing the same>

[0064] FIG. 1 is a schematic cross-sectional view of a main part to explain the configuration of a reflective mask blank (100) of the present embodiment. As shown in FIG. 1, the reflective mask blank (100) has a substrate (1), a multilayer reflective film (2), a protective film (3), and an absorber film (4), and has a structure in which these are stacked in this order. The multilayer reflective film (2) is formed on the first main surface (surface side) and reflects EUV light, which is exposure light, with a high reflectivity. The protective film (3) is installed to protect the multilayer reflective film (2) and is formed of a material that is resistant to the etchant and cleaning solution used when patterning the absorber film (4) described later. The absorber film (4) absorbs EUV light and simultaneously has a phase shift function. Also, on the second main surface (back side surface) of the substrate (1), a conductive film (not shown) for an electrostatic chuck is formed. Additionally, an etching mask film may be formed on the absorbent film (4).

[0065] In this specification, the phrase “having a multilayer reflective film (2) on the main surface of the substrate (1)” includes cases where the multilayer reflective film (2) is arranged in contact with the surface of the substrate (1), as well as cases where another film is arranged between the substrate (1) and the multilayer reflective film (2). The same applies to other films. For example, the phrase “having a film B on film A” includes cases where, in addition to meaning that film A and film B are arranged to be in direct contact, another film is arranged between film A and film B. Furthermore, in this specification, for example, the phrase “film A is arranged in contact with the surface of film B” means that film A and film B are arranged to be in direct contact without interposing another film between film A and film B.

[0066] Hereinafter, the present embodiment will be described for each layer.

[0067] <<Board (1)>>

[0068] In order to prevent distortion of the absorber pattern (transfer pattern) (4a) (see FIG. 2) caused by heat during exposure to EUV light, the substrate (1) is preferably used to have a low coefficient of thermal expansion within the range of 0±5 ppb / ℃. For example, materials having a low coefficient of thermal expansion within this range may be used, such as SiO2-TiO2 glass, multi-component glass ceramics, etc.

[0069] The first main surface on the side where the transfer pattern of the substrate (1) (the absorber pattern (4a) described later corresponds to this) is formed is surface-processed to have high flatness at least from the perspective of obtaining pattern transfer precision and positional precision. In the case of EUV exposure, in the 132 mm × 132 mm area of ​​the main surface (first main surface) on the side where the transfer pattern of the substrate (1) is formed, it is preferable that the flatness is 0.1 μm or less, more preferably 0.05 μm or less, and particularly preferably 0.03 μm or less. In addition, the second main surface on the side opposite to the side where the transfer pattern is formed is a surface that is electrostatically chucked when set in the exposure device, and in the 132 mm × 132 mm area, it is preferable that the flatness is 0.1 μm or less, more preferably 0.05 μm or less, and particularly preferably 0.03 μm or less. In addition, the flatness of the second main side of the reflective mask blank (100) is preferably 1 μm or less in the area of ​​142 mm × 142 mm, more preferably 0.5 μm or less, and particularly preferably 0.3 μm or less.

[0070] In addition, the high surface smoothness of the substrate (1) is also an extremely important factor. The surface roughness of the first main surface of the substrate (1) is preferably 0.1 nm or less in root mean square roughness (RMS). In addition, the surface smoothness can be measured using an atomic force microscope.

[0071] In addition, the substrate (1) is preferably to have high rigidity to suppress deformation caused by film stress of a film (multilayer reflective film (2), etc.) formed thereon. In particular, the substrate (1) is preferably to have a high Young's modulus of 65 GPa or higher.

[0072] <<Multilayer reflective film (2)>>

[0073] The multilayer reflective film (2) is a multilayer film in which each layer, composed of elements with different refractive indices, is periodically stacked to provide the function of reflecting EUV light in the reflective mask (200).

[0074] Generally, a multilayer film in which a thin film of a light element or its compound, which is a high refractive index material (high refractive index layer), and a thin film of a heavy element or its compound, which is a low refractive index material (low refractive index layer), are alternately stacked for about 40 to 60 cycles is used as a multilayer reflective film (2). The multilayer film may be stacked in multiple cycles with a stacking structure of a high refractive index layer / low refractive index layer, in which a high refractive index layer and a low refractive index layer are stacked in this order from the substrate (1) side, with one cycle being a stacking structure of a low refractive index layer / high refractive index layer. Also, the multilayer film may be stacked in multiple cycles with a stacking structure of a low refractive index layer / high refractive index layer, in which a low refractive index layer and a high refractive index layer are stacked in this order from the substrate (1) side, with one cycle being a stacking structure of a low refractive index layer / high refractive index layer. In addition, it is preferable that the outermost layer of the multilayer reflective film (2), that is, the surface layer opposite to the substrate (1) of the multilayer reflective film (2), be a high refractive index layer. In the multilayer film described above, when a stacking structure of a high refractive index layer and a low refractive index layer stacked in this order from the substrate (1) side is stacked in multiple cycles, the uppermost layer becomes a low refractive index layer. In this case, if the low refractive index layer constitutes the outermost surface of the multilayer reflective film (2), it oxidizes easily, and the reflectivity of the reflective mask (200) decreases. Therefore, it is preferable to form a high refractive index layer on the uppermost low refractive index layer to form the multilayer reflective film (2). Meanwhile, in the case of the multilayer film described above, when a stacking structure of a low refractive index layer and a high refractive index layer stacked in this order from the substrate (1) side is stacked multiple times with one cycle, the top layer becomes a high refractive index layer, so it may be left as is.

[0075] In this embodiment, a layer containing silicon (Si) is used as the high refractive index layer. As a material containing Si, in addition to Si alone, Si compounds containing boron (B), carbon (C), nitrogen (N), and oxygen (O) in Si can be used. By using a layer containing Si as the high refractive index layer, a reflective mask (200) for EUV lithography with excellent reflectivity of EUV light is obtained. Also, in this embodiment, a glass substrate is preferably used as the substrate (1). Si also has excellent adhesion to the glass substrate. Also, as the low refractive index layer, a metal alone selected from molybdenum (Mo), ruthenium (Ru), rhodium (Rh), and platinum (Pt), or an alloy thereof, is used. For example, as a multilayer reflective film (2) for EUV light with a wavelength of 13 nm to 14 nm, preferably, a Mo / Si periodic stacked film is used in which Mo films and Si films are alternately stacked for about 40 to 60 periods. In addition, the high refractive index layer, which is the uppermost layer of the multilayer reflective film (2), may be formed of silicon (Si).

[0076] The reflectance of the multilayer reflective film (2) alone is typically 65% ​​or more, and the upper limit is typically 73%. In addition, the film thickness and period of each constituent layer of the multilayer reflective film (2) can be appropriately selected according to the exposure wavelength and selected to satisfy the Bragg law of reflection. In the multilayer reflective film (2), there are multiple high-refractive-index layers and low-refractive-index layers, but the film thicknesses of the high-refractive-index layers and the low-refractive-index layers do not have to be the same. Also, the film thickness of the outermost Si layer of the multilayer reflective film (2) can be adjusted within a range that does not reduce the reflectance. The film thickness of the outermost Si layer (high-refractive-index layer) can be in the range of 3 nm to 10 nm.

[0077] The method of forming a multilayer reflective film (2) is known in the art. For example, it can be formed by depositing each layer of the multilayer reflective film (2) by an ion beam sputtering method. In the case of the Mo / Si periodic stacked film described above, for example, by an ion beam sputtering method, a Si film with a thickness of about 4 nm is first deposited on a substrate (1) using a Si target. Then, a Mo film with a thickness of about 3 nm is deposited using a Mo target. With this Si film / Mo film as one period, 40 to 60 periods are stacked to form a multilayer reflective film (2) (the outermost layer is a Si layer). Also, for example, if the multilayer reflective film (2) is made up of 60 periods, the number of process steps increases compared to 40 periods, but the reflectivity for EUV light can be increased. In addition, when forming the multilayer reflective film (2), it is preferable to form the multilayer reflective film (2) by supplying krypton (Kr) ion particles from an ion source and performing ion beam sputtering.

[0078] <<Protective Shield (3)>>

[0079] In the present embodiment, the reflective mask blank (100) preferably has a protective film (3) between the multilayer reflective film (2) and the absorbent film (4).

[0080] In order to protect the multilayer reflective film (2) from dry etching and cleaning during the manufacturing process of the reflective mask (200) described later, a protective film (3) may be formed on the multilayer reflective film (2) or in contact with the surface of the multilayer reflective film (2). The protective film (3) is formed of a material that is resistant to the etchant and cleaning solution used when patterning the absorber film (4). By forming the protective film (3) on the multilayer reflective film (2), damage to the surface of the multilayer reflective film (2) can be suppressed when manufacturing the reflective mask (200) (EUV mask) using a substrate (1) having the multilayer reflective film (2) and the protective film (3). As a result, the reflectance characteristics of the multilayer reflective film (2) with respect to EUV light are improved.

[0081] In the case where the absorbent film (4) in contact with the surface of the protective film (3) is a thin film made of a material containing ruthenium (Ru) (Ru-based material), a material selected from silicon-based materials such as silicon (Si), a material containing silicon (Si) and oxygen (O), a material containing silicon (Si) and nitrogen (N), or a material containing silicon (Si), oxygen (O) and nitrogen (N) can be used as the material of the protective film (3).

[0082] Meanwhile, if the absorbent film (4) in contact with the surface of the protective film (3) is a thin film made of a tantalum-based material or a chromium-based material, it is preferable that the protective film (3) contains ruthenium. The material of the protective film (3) may be a single Ru metal, or a Ru 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), and may also contain nitrogen.

[0083] In EUV lithography, since there are few materials that are transparent to the exposure light, it is not technically simple to use an EUV pellicle to prevent foreign matter from adhering to the mask pattern surface. For this reason, the operation of pellicles that do not use pellicles has become the mainstream. Also, in EUV lithography, exposure contamination occurs, such as carbon film deposition or oxide film growth on the reflective mask due to EUV exposure. Therefore, when the EUV exposure reflective mask (200) is used in the manufacturing of a semiconductor device, it is necessary to frequently clean the mask to remove foreign matter or contamination. For this reason, the EUV exposure reflective mask (200) requires a mask cleaning resistance that is significantly different from that of a transmissive mask for photolithography. By having a protective film (3) on the reflective mask (200), the cleaning resistance to the cleaning solution can be increased.

[0084] The film thickness of the protective film (3) is not particularly limited as long as it can perform the function of protecting the multilayer reflective film (2). In terms of the reflectance of EUV light, the film thickness of the protective film (3) is preferably 1.0 nm or more and 8.0 nm or less, more preferably 1.5 nm or more and 6.0 nm or less.

[0085] As for the method of forming the protective film (3), any method similar to known film forming methods may be adopted without particular limitation. Specific examples include sputtering and ion beam sputtering methods.

[0086] <<Absorbent Membrane>>

[0087] In the reflective mask blank (100) of the present embodiment, an absorbent film (a thin film for pattern formation) (4) is formed on the multilayer reflective film (2) or on the protective film (3) formed on the multilayer reflective film (2). In the state of the reflective mask (200), an absorbent pattern (4a) is formed on the absorbent film (4), and this absorbent pattern (4a) constitutes a transfer pattern.

[0088] In the absorbing film (4), the relative reflectance R of the multilayer reflective film (2) with respect to the reflectance of the EUV exposure light (center wavelength 13.5 nm) is preferably 1% or more, and more preferably 2% or more. In addition, the relative reflectance R is preferably 40% or less. This is to ensure sufficient contrast in the pattern image during exposure transfer while simultaneously ensuring sufficient contrast in the mask inspection for the EUV exposure light.

[0089] In the reflective mask (200) described later in this embodiment, in the portion where the absorber film (4) (absorber pattern (4a)) is installed, EUV light is absorbed and reduced, while some light is reflected at a level that does not adversely affect pattern transfer. Meanwhile, in the opening (the portion where the absorber film (4) is not present), EUV light is reflected from the multilayer reflective film (2) (if there is a protective film (3), from the multilayer reflective film (2) via the protective film (3)). The reflected light from the portion where the absorber film (4) is formed forms a desired phase difference with the reflected light from the opening. The absorber film (4) has a wavelength λ M For light of (= 13.5 nm), the phase difference between the reflected light from the absorbing film (4) and the reflected light from the multilayer reflective film (2) is formed to be 130 to 230 degrees. As light with an inverted phase difference of around 180 degrees or around 220 degrees interferes with each other at the pattern edge, the image contrast of the projected optical image is improved. Along with the improvement in image contrast, the resolution increases, and various margins related to exposure, such as exposure amount margin and focus margin, are expanded.

[0090] The absorbing film (4) is made of a material containing a metal element. This metal element can be a metal element in a broad sense and can be selected from alkali metals, alkaline earth metals, transition metals, and metalloids. The absorbing film (4) can be selected from the metal elements in the broad sense described above as long as it has etching selectivity with the multilayer reflective film (2) (etching selectivity with the protective film (3) if the protective film (3) is formed). For example, chromium (Cr), vanadium (V), palladium (Pd), titanium (Ti), iridium (Ir), Rh (rhodium), tantalum (Ta), niobium (Nb), molybdenum (Mo), ruthenium (Ru), tin (Sn), platinum (Pt), etc. can be used as the metal element contained in the absorbing film (4).

[0091] Additionally, the absorbent membrane (4) may contain at least one selected from oxygen, nitrogen, carbon, and boron within a range that does not deviate from the effects of the present invention.

[0092] The absorbing membrane (4) has a wavelength λ L n = the refractive index for light of 13.2 nm L , wavelength λ M = refractive index for light of 13.5 nm is n M , wavelength λ H = refractive index for light of 13.8 nm, n H , coefficient P=[(1-n H ) / λ H -(1-n L ) / λ L ] / [(1-n M ) / λ M When ], the absolute value of the coefficient P becomes 0.09 or less. By this, when photolithography is performed with an EUV exposure device, wavelength range λ L ~λ H Phase difference Δφ (=φ) in EUV light H -φ L It becomes possible to suppress the size of ) to 20 degrees or less.

[0093] Also, the absorbing film (4) is a wavelength range λ of EUV light L = 13.2 nm ~ λ H At 13.8 nm, if the absolute value of the coefficient P is 0.085 or less, it is desirable in that the phase difference Δφ can be suppressed to within 18 degrees. Also, the absorbing film (4) is of the wavelength range λ of EUV light. L = 13.2 nm ~ λ H At 13.8 nm, if the absolute value of the coefficient P is 0.07 or less, it is more preferable in that the phase difference Δφ can be suppressed to within 15 degrees. In addition, the absorbing film (4) is a wavelength band λ of EUV light L = 13.2 nm ~ λ HAt = 13.8 nm, if the absolute value of the coefficient P is 0.045 or less, it is more desirable in that the phase difference Δφ can be suppressed to within 10 degrees.

[0094] The absorbing membrane (4) has a wavelength λ L n is the refractive index for light of = 13.0 nm L , wavelength λ M = refractive index for light of 13.5 nm is n M , wavelength λ H n is the refractive index for light of = 14.0 nm H , coefficient P=[(1-n H ) / λ H -(1-n L ) / λ L ] / [(1-n M ) / λ M When ], the absolute value of the coefficient P becomes 0.15 or less. By this, when photolithography is performed with an EUV exposure device, wavelength range λ L ~λ H Phase difference Δφ (=φ) in EUV light H -φ L It becomes possible to suppress the size of ) to 35 degrees or less.

[0095] Also, the absorbing film (4) is a wavelength range λ of EUV light L = 13.0 nm ~ λ H At 14.0 nm, if the absolute value of the coefficient P is 0.14 or less, it is desirable in that the phase difference Δφ can be suppressed to within 30 degrees. Also, the absorbing film (4) is of the wavelength range λ of EUV light. L = 13.0 nm ~ λ H In the case of = 14.0 nm, if the absolute value of the coefficient P is 0.11 or less, it is more preferable in that the phase difference Δφ can be suppressed to within 25 degrees. In addition, the absorbing film (4) is a wavelength band λ of EUV light L = 13.0 nm ~ λ HAt = 14.0 nm, if the absolute value of the coefficient P is 0.09 or less, it is more desirable in that the phase difference Δφ can be suppressed to within 20 degrees.

[0096] As for the material of the absorbent membrane (4), as described above, tantalum-based materials or chromium-based materials may be preferably used, although they are not particularly limited. As for the tantalum-based material, in addition to tantalum metal, it is preferable to use a material containing one or more elements selected from nitrogen (N), oxygen (O), boron (B), and carbon (C) in tantalum (Ta). Among these, it is preferable to include at least one element selected from tantalum (Ta) and oxygen (O) and boron (B). Also, when the absorbent membrane (4) is formed from a material containing chromium, in addition to chromium metal, it is preferable to use a material containing one or more elements selected from oxygen (O), nitrogen (N), carbon (C), boron (B), and fluorine (F) in chromium (Cr). In particular, a material containing a chromium (Cr) nitride is preferred.

[0097] Also, the wavelength λ of the absorbing membrane (4) M Refractive index n for light of (=13.5 nm) M It is preferable if the value is 0.960 or lower, and more preferable if it is 0.955 or lower. Also, the refractive index n of the absorbing membrane (4) M It is desirable if it is 0.850 or higher, and more desirable if it is 0.870 or higher.

[0098] Wavelength λ of the absorbing membrane (4) M The decay coefficient k for light M It is preferable if it is 0.10 or less, more preferable if it is 0.08 or less, and even more preferable if it is 0.05 or less. Based on the results of the optical simulation, the light intensity of the reflected light from the multilayer reflective film (2) is stronger than that of the reflected light from the absorbing film (4) for light of wavelength 13.5 nm, and the decay coefficient k of the absorbing film (4) MIt is inferred that as this increases, the reflected light of the absorbing film (4) decreases. Decay coefficient k M It is inferred that by making the above range, the reduction of reflected light of the absorbing film (4) can be suppressed, so it is desirable.

[0099] In order to obtain a phase shift effect, depending on the pattern or exposure conditions, the absolute reflectance of the transfer pattern (absorber pattern (4a)) with respect to EUV light (center wavelength 13.5 nm) is preferably 1% to 30%, and more preferably 2% to 25%.

[0100] The phase difference and reflectance of the absorbing film (4) are the refractive index n in the EUV exposure light. L , n M , n H , decay coefficient k L , k M , k H It is possible to adjust by changing the film thickness d. The film thickness of the absorber film (4) is preferably less than 100 nm, more preferably 98 nm or less, and even more preferably 90 nm or less. The film thickness of the absorber film (4) is preferably 30 nm or more. In addition, when a protective film (3) is provided, the phase difference and reflectance of the absorber film (4) may be adjusted by taking into account the refractive index n, decay coefficient k, and film thickness of the protective film (3).

[0101] The absorber film (4) of the aforementioned predetermined material can be formed by known methods such as sputtering methods including DC sputtering and RF sputtering, and reactive sputtering methods using oxygen gas. The target may include one type of metal, and if the absorber film (4) is composed of two or more types of metals, an alloy target including two or more types of metals (e.g., Ru and Cr) may be used. Also, if the absorber film (4) is composed of two or more types of metals, the thin film constituting the absorber film (4) may be formed by co-sputtering using, for example, a Ru target and a Cr target.

[0102] Additionally, the absorbent membrane (4) may be a multilayer membrane comprising two or more layers. In this case, it is desirable to satisfy the condition that the absolute value of the coefficient P is 0.09 or less in all layers of the absorbent membrane (4).

[0103] <<Etching Mask>>

[0104] An etching mask film (not shown) may be formed on the absorber film (4) or in contact with the surface of the absorber film (4). As the material for the etching mask film, a material such as one that increases the etching selectivity ratio of the absorber film (4) to the etching mask film is used. Here, "etching selectivity ratio of B to A" refers to the ratio of the etching rate between A, which is a layer that does not need to be etched (a layer that serves as a mask), and B, which is a layer that needs to be etched. Specifically, it is determined by the formula "etching selectivity ratio of B to A = etching rate of B / etching rate of A". Also, "high selectivity ratio" means that the value of the selectivity ratio defined above is large relative to the comparison target. The etching selectivity ratio of the absorber film (4) to the etching mask film is preferably 1.5 or higher, and more preferably 3 or higher.

[0105] The thickness of the etching mask film is preferably 2 nm or more in order to obtain the function of an etching mask that forms a transfer pattern on the absorber film (4) with high precision. In addition, the thickness of the etching mask film is preferably 15 nm or less in order to reduce the thickness of the resist film.

[0106] <<Challenge>>

[0107] On the second main surface (this side surface) of the substrate (1) (opposite side to the surface on which the multilayer reflective film (2) is formed), a conductive film (not shown) for an electrostatic chuck is generally formed. The electrical characteristics (sheet resistance) required for the conductive film for the electrostatic chuck are typically 100Ω / □ (Ω / Square) or less. The conductive film can be formed, for example, by magnetron sputtering or ion beam sputtering, using a target of a metal or alloy such as chromium (Cr) and tantalum (Ta).

[0108] The chromium (Cr)-containing material of the conductive film is preferably a Cr compound containing Cr and additionally containing at least one selected from boron (B), nitrogen (N), oxygen (O), and carbon (C).

[0109] As a material containing tantalum (Ta) for a conductive film, it is preferable to use Ta (tantalum), an alloy containing Ta, or a Ta compound containing at least one of boron, nitrogen, oxygen, and carbon in any of these.

[0110] The thickness of the conductive film is not particularly limited as long as it satisfies the function as an electrostatic chuck. The thickness of the conductive film is typically 10 nm to 200 nm. In addition, this conductive film also serves to adjust the stress on the second main side of the mask blank (100). That is, the conductive film balances the stress from various films formed on the first main side, and is adjusted so that a flat reflective mask blank (100) is obtained.

[0111] <Reflective mask (200) and method of manufacturing the same>

[0112] The reflective mask (200) of the present embodiment has a transfer pattern (absorber pattern (4a)) formed on the absorber film (4) of the reflective mask blank (100). The absorber film (4) (absorber pattern (4a)) on which the transfer pattern is formed is the same as the absorber film (4) of the reflective mask blank (100) of the present embodiment described above. By patterning the absorber film (4) of the reflective mask blank (100) of the present embodiment described above, the transfer pattern (absorber pattern (4a)) can be formed. Patterning of the absorber film (4) can be performed using a predetermined dry etching gas. The absorber pattern (4a) of the reflective mask (200) can absorb EUV light and also reflect some of the EUV light with a predetermined phase difference from the aperture (part where the absorber pattern (4a) is not formed). The above-mentioned predetermined dry etching gas may be a mixture of chlorine-based gas and oxygen gas, oxygen gas, and fluorine-based gas. In order to pattern the absorber pattern (4a), an etching mask film may be installed on the absorber pattern (4a) as needed. In that case, the absorber pattern (4a) can be formed by dry etching the absorber film (4) using the etching mask pattern as a mask.

[0113] A method for manufacturing a reflective mask (200) using the reflective mask blank (100) of the present embodiment will be described.

[0114] A reflective mask blank (100) is prepared, and a resist film is formed on the first absorbent film (4) of the same (this step is not required if the reflective mask blank (100) is equipped with a resist film). A desired transfer pattern is drawn (exposed) on this resist film, and a predetermined resist pattern (a resist film having a transfer pattern) is formed by further developing and rinsing.

[0115] Next, using this resist pattern as a mask, the absorber film (4) is etched to form an absorber pattern (4a) (an absorber film (4) having a transfer pattern). After forming the absorber pattern (4a), the remaining resist pattern is removed (if an etching mask film is formed, the etching mask film is etched using the resist pattern as a mask to form an etching mask pattern, the absorber pattern (4a) is formed using this etching mask pattern as a mask, and the etching mask pattern is removed).

[0116] Finally, the reflective mask (200) of the present embodiment is manufactured by performing wet cleaning using an acidic or alkaline aqueous solution.

[0117] <Method for manufacturing a semiconductor device>

[0118] The present embodiment is a method for manufacturing a semiconductor device comprising a process of exposing and transferring a transfer pattern onto a resist film on a semiconductor substrate using the reflective mask (200) described above or a reflective mask (200) manufactured by the method of manufacturing the reflective mask (200) described above. By setting the reflective mask (200) of the present embodiment in an exposure device having an exposure light source of EUV light and transferring the transfer pattern onto a resist film formed on a substrate to be transferred, a semiconductor device can be manufactured. Accordingly, a semiconductor device having a fine and high-precision transfer pattern can be manufactured.

[0119] [Examples and Comparative Examples]

[0120] Examples 1 to 16, Comparative Examples 1 and 2

[0121] Hereinafter, Examples 1 to 16 and Comparative Examples 1 and 2 will be described with reference to the drawings. The present embodiment is not limited to these examples. In addition, in the examples, the same reference numerals are used for similar components, and descriptions are simplified or omitted.

[0122] As Examples 1 to 16 and Comparative Examples 1 and 2, a method for manufacturing a reflective mask blank (100) will be described.

[0123] A SiO2-TiO2 glass substrate, which is a low thermal expansion glass substrate of size 6025 (approx. 152 mm × 152 mm × 6.35 mm) with both main surfaces of the first and second main surfaces polished, was prepared and used as the substrate (1). Polishing was performed, consisting of a rough polishing process, a precision polishing process, a local processing process, and a touch polishing process, in order to obtain a flat and smooth main surface.

[0124] Next, a conductive film made of CrN was formed on the second main surface (secondary surface) of the SiO2-TiO2 glass substrate (1) by magnetron sputtering (reactive sputtering) under the following conditions. The conductive film was formed using a Cr target in a mixed gas atmosphere of argon (Ar) gas and nitrogen (N2) gas to a thickness of 20 nm.

[0125] Next, a multilayer reflective film (2) was formed on the main surface (first main surface) of the substrate (1) opposite to the side where the conductive film was formed. The multilayer reflective film (2) formed on the substrate (1) was made into a periodic stacked reflective film composed of molybdenum (Mo) and silicon (Si) in order to be a multilayer reflective film (2) suitable for EUV light of a wavelength of 13.5 nm. The multilayer reflective film (2) was formed by alternately stacking Mo layers and Si layers on the substrate (1) by using a Mo target and a Si target and an ion beam sputtering method in a krypton (Kr) gas atmosphere. First, a Si film was deposited with a film thickness of 4.2 nm, and then a Mo film was deposited with a film thickness of 2.8 nm. This was done as one cycle, and 40 cycles were stacked in the same manner, and finally, a Si film was deposited with a film thickness of 4.0 nm to form the multilayer reflective film (2).

[0126] Next, a protective film (3) was formed on the surface of a multilayer reflective film (2) by sputtering in an Ar gas atmosphere to a thickness of 3.5 nm. In addition, in the above-described Examples 1 to 16 and Comparative Examples 1 and 2, the material of the protective film (3) was appropriately selected to have etching resistance to the dry etching gas used when patterning the absorber film (4).

[0127] Next, an absorber film (4) was formed on the surface of the protective film (3) by sputtering in an Ar gas atmosphere. In the above-described Examples 1 to 16 and Comparative Examples 1 and 2, the constituent elements of the absorber film (4) are shown in Tables 1-1 and 1-2 below, and a sputtering target suitable for each constituent element was appropriately selected. Furthermore, in the above-described Examples 1 to 16 and Comparative Examples 1 and 2, the absorber film (4) is a central wavelength λ of EUV light M Phase difference φ in M It is designed to be 1.2π (216 degrees).

[0128] After that, a reflective mask blank (100) in Examples 1 to 16 and Comparative Examples 1 and 2 was manufactured by performing a predetermined cleaning treatment, etc.

[0129] Next, regarding the reflective mask blank (100) in Examples 1 to 16 and Comparative Examples 1 and 2, a resist pattern was formed as described in the method for manufacturing the reflective mask (200) described above, and using the resist pattern as a mask, the absorbent film (4) was etched to form an absorbent pattern (4a) (an absorbent film (4) having a transfer pattern), and wet cleaning was performed using an acidic or alkaline aqueous solution to manufacture the reflective mask (200) in Examples 1 to 16 and Comparative Examples 1 and 2.

[0130] In the reflective mask blank (100) and reflective mask (200) of Examples 1 to 16 and Comparative Examples 1 and 2, the constituent elements of the absorber film (4) and the center wavelength λ of EUV lightM Refractive index n at (=13.5 nm) M and decay coefficient k M , wavelength λ L = 13.2 nm, λ M = 13.5 nm, λ H = Coefficient A at 13.8 nm L = 4π×(1-n L ) / λ L , A M = 4π×(1-n M ) / λ M , A H = 4π×(1-n H ) / λ H , film thickness d, EUV light wavelength λ L = 13.2 nm ~ λ H = at 13.8 nm, coefficient P = (A H -A L ) / A M (=[(1-n H ) / λ H -(1-n L ) / λ L ] / [(1-n M ) / λ M ]), and the phase difference Δφ are shown in Table 1-1 and Table 1-2.

[0131] [Table 1-1]

[0132]

[0133] [Table 1-2]

[0134]

[0135] As shown in Tables 1-1 and 1-2, the absorbing film (4) shown in Examples 1 to 16 all have a film thickness of less than 100 nm and a wavelength range λ of EUV light L = 13.2 nm ~ λ H At 13.8 nm, the absolute value of the coefficient P is 0.09 or less, and the phase difference Δφ can be suppressed to within 20 degrees. The absorbing film (4) shown in Examples 1 to 11 and 16 also has a wavelength band λ of EUV light L = 13.2 nm ~ λH At =13.8 nm, the absolute value of the coefficient P is 0.085 or less, and the phase difference Δφ can be suppressed to within 18 degrees. In addition, the absorbing film (4) shown in Examples 1 to 6 and 16 is for the wavelength range λ of EUV light L = 13.2 nm ~ λ H At =13.8 nm, the absolute value of the coefficient P is 0.07 or less, and the phase difference Δφ can be suppressed to within 15 degrees. In addition, the absorbing film (4) shown in Examples 1 to 3 is for the wavelength range λ of EUV light L = 13.2 nm ~ λ H At 13.8 nm, the absolute value of the coefficient P is 0.045 or less, and the phase difference Δφ can be suppressed to within 10 degrees.

[0136] Meanwhile, in Comparative Example 1, the wavelength band λ of EUV light L = 13.2 nm ~ λ H In the case of 13.8 nm, the phase difference Δφ of the absorbing film (4) is 22.49, which is over 20 degrees and has a phase difference Δφ that cannot be ignored. Also, in Comparative Example 2, the film thickness of the absorbing film (4) is 183.31 nm, which is significantly higher than less than 100 nm.

[0137] Also, in Tables 1-1 and 1-2, for Examples 1 to 16 and Comparative Examples 1 and 2, the wavelength band λ of EUV light L = 13.0 nm ~ λ H Coefficient A at =14.0 nm L = 4π×(1-n L ) / λ L , A H = 4π×(1-n H ) / λ H , coefficient P=(A H -A L ) / A M , and the phase difference Δφ is also shown. As shown in Tables 1-1 and 1-2, the absorbing film (4) shown in Examples 1 to 16 is in the wavelength range λ of EUV light. L = 13.0 nm ~ λH At =14.0 nm, the absolute value of the coefficient P is 0.15 or less, and the phase difference Δφ can be suppressed to within 35 degrees. In addition, the absorbing film (4) shown in Examples 1 to 12 and 16 is for the wavelength range λ of EUV light L = 13.0 nm ~ λ H At =14.0 nm, the absolute value of the coefficient P is 0.14 or less, and the phase difference Δφ can be suppressed to within 30 degrees. In addition, the absorbing film (4) shown in Examples 1 to 6 and 16 is for the wavelength range λ of EUV light L = 13.0 nm ~ λ H At 14.0 nm, the absolute value of the coefficient P is 0.11 or less, and the phase difference Δφ can be suppressed to within 25 degrees. In addition, the absorbing film (4) shown in Examples 1 to 5 and 16 is for the wavelength range λ of EUV light L = 13.0 nm ~ λ H At 14.0 nm, the absolute value of the coefficient P is 0.09 or less, and the phase difference Δφ can be suppressed to within 20 degrees.

[0138] Also, in the reflective mask blank (100) and reflective mask (200) of Examples 1 to 16 and Comparative Examples 1 and 2, the constituent elements of the absorbing film (4) and the wavelength λ L = 13.2 nm, λ M = 13.5 nm, λ H = Coefficient E at 13.8 nm L = 4π×(1-k L ) / λ L , E M = 4π×(1-k M ) / λ M , E H = 4π×(1-k H ) / λ H , wavelength band λ of EUV light L = 13.2 nm ~ λ H At =13.8 nm, coefficient F=(E H -E L ) / E M (=[(1-kH ) / λ H -(1-k L ) / λ L ] / [(1-k M ) / λ M Regarding ]), it is shown in Tables 2-1 and 2-2 (k L , k M , k H is, wavelength λ L = 13.2 nm, λ M = 13.5 nm, λ H = is the decay coefficient at 13.8 nm). Also, in Tables 2-1 and 2-2, for Examples 1 to 16 and Comparative Examples 1 and 2, the wavelength band λ of EUV light L = 13.0 nm ~ λ H coefficient E at = 14.0 nm L = 4π×(1-k L ) / λ L , E M = 4π×(1-k M ) / λ M , E H = 4π×(1-k H ) / λ H , wavelength band λ of EUV light L = 13.0 nm ~ λ H At =14.0 nm, coefficient F=(E H -E L ) / E M (=[(1-k H ) / λ H -(1-k L ) / λ L ] / [(1-k M ) / λ M ]) also indicates.

[0139] [Table 2-1]

[0140]

[0141] [Table 2-2]

[0142]

[0143] Regarding the decay coefficient k, no significant difference was found in Examples 1 to 16 and Comparative Examples 1 and 2.

[0144] The reflective mask (200) obtained by Examples 1 to 16 is set in an EUV scanner, and EUV exposure is performed on a wafer having a film to be processed and a resist film formed on a semiconductor substrate, and the exposed resist film is developed so that the film to be processed forms a resist pattern on the semiconductor substrate.

[0145] The reflective mask (200) obtained by Examples 1 to 16 has a center wavelength λ of EUV light. M Phase difference φ in M This is 1.2π, and the wavelength band λ of EUV light L = 13.2 nm ~ λ H At 13.8 nm, an absorber pattern (4a) is provided in which the absolute value of the coefficient P is 0.09 or less. By this, when EUV light is used as exposure light, the wavelength band λ of the EUV light L = 13.2 nm ~ λ H At 13.8 nm, the phase difference Δφ can be suppressed to within 20 degrees, the required fine pattern can be formed with high precision, and a semiconductor device having a fine and high-precision transfer pattern can be manufactured.

[0146] Additionally, by transferring this resist pattern to a workpiece by etching, and by undergoing various processes such as forming an insulating film, forming a conductive film, introducing a dopant, or annealing, it was possible to manufacture a semiconductor device with desired characteristics with a high yield.

[0147] The reflective mask (200) of Comparative Example 1 is a wavelength band λ of EUV light. L = 13.2 nm ~ λ H At 13.8 nm, an absorber pattern (4a) is provided in which the absolute value of the coefficient P exceeds 0.09. As a result, when EUV light is used as exposure light, the wavelength band λ of the EUV light L = 13.2 nm ~ λ HAt 13.8 nm, the phase difference Δφ was 22.49 degrees, which could not be suppressed to within 20 degrees, so the phase shift effect could not be sufficiently obtained. Consequently, the required fine pattern could not be formed with high precision, and thus it was not possible to manufacture a semiconductor device having a fine and high-precision transfer pattern.

[0148] In addition, by transferring this resist pattern to a workpiece by etching and undergoing various processes such as forming an insulating film, forming a conductive film, introducing a dopant, or annealing, it was not possible to manufacture a semiconductor device with desired characteristics with a high yield.

[0149] The reflective mask (200) of Comparative Example 2 has an absorber film (4) composed of SiO2 and does not contain metal elements. As a result, the film thickness of the absorber film (4) is 184.31 nm, which is significantly higher than 100 nm, so good transfer characteristics cannot be obtained, and a semiconductor device having a fine and high-precision transfer pattern cannot be manufactured.

[0150] In addition, by transferring this resist pattern to a workpiece by etching and undergoing various processes such as forming an insulating film, forming a conductive film, introducing a dopant, or annealing, it was not possible to manufacture a semiconductor device with desired characteristics with a high yield. Explanation of the symbols

[0151] 1: Substrate 2: Multilayer reflective film 3: Protective layer 4: Absorbent film (film for pattern formation) 4a: Absorbent pattern (transfer pattern) 100: Reflective mask blank 200: Reflective mask

Claims

Claim 1 A mask blank having a multilayer reflective film and a pattern-forming thin film installed in this order on the main surface of a substrate, wherein the thin film is made of a material containing metal, and the wavelength λ of the thin film L n is the refractive index for light of = 13.0 nm L , wavelength λ of the above thin film M = refractive index for light of 13.5 nm is n M , wavelength λ of the above thin film H n is the refractive index for light of = 14.0 nm H , coefficient P=[(1-n H ) / λ H -(1-n L ) / λ L ] / [(1-n M ) / λ M A mask blank characterized in that, when [it is said], the absolute value of the coefficient P is greater than 0 and less than or equal to 0.

15. Claim 2 In claim 1, the wavelength λ M The refractive index n of the above thin film with respect to light M A mask blank characterized by being greater than 0 and less than or equal to 0.

96. Claim 3 A mask blank according to claim 1, characterized in that the thickness of the thin film is greater than 0 and less than 100 nm. Claim 4 A mask blank according to claim 1, wherein the metal is at least one selected from chromium (Cr), vanadium (V), palladium (Pd), titanium (Ti), iridium (Ir), rhodium (Rh), tantalum (Ta), niobium (Nb), molybdenum (Mo), ruthenium (Ru), tin (Sn), and platinum (Pt). Claim 5 A mask blank according to claim 1, characterized in that the thin film is a multilayer film comprising two or more layers. Claim 6 A mask blank characterized by having a protective film between the multilayer reflective film and the thin film in any one of claims 1 to 5. Claim 7 In any one of claims 1 to 5, the thin film is, the wavelength λ M A mask blank characterized by generating a phase difference of 130 to 230 degrees between the reflected light from the thin film and the reflected light from the multilayer reflective film with respect to light. Claim 8 A reflective mask in which a multilayer reflective film and a thin film having a transfer pattern formed thereon are installed in this order on the main surface of a substrate, wherein the thin film is made of a material containing metal, and the wavelength λ of the thin film L n is the refractive index for light of = 13.0 nm L , wavelength λ of the above thin film M = refractive index for light of 13.5 nm is n M , wavelength λ of the above thin film H n is the refractive index for light of = 14.0 nm H , coefficient P=[(1-n H ) / λ H -(1-n L ) / λ L ] / [(1-n M ) / λ M A reflective mask characterized in that, when [it is said], the absolute value of the coefficient P is greater than 0 and less than or equal to 0.

15. Claim 9 In claim 8, the wavelength λ M The refractive index n of the above thin film with respect to light M A reflective mask characterized by being greater than 0 and less than or equal to 0.

96. Claim 10 A reflective mask according to claim 8, characterized in that the thickness of the thin film is greater than 0 and less than 100 nm. Claim 11 A reflective mask according to claim 8, characterized in that the metal is at least one selected from chromium (Cr), vanadium (V), palladium (Pd), titanium (Ti), iridium (Ir), rhodium (Rh), tantalum (Ta), niobium (Nb), molybdenum (Mo), ruthenium (Ru), tin (Sn), and platinum (Pt). Claim 12 A reflective mask according to claim 8, characterized in that the thin film is a multilayer film comprising two or more layers. Claim 13 A reflective mask characterized by having a protective film between the multilayer reflective film and the thin film in any one of claims 8 to 12. Claim 14 In any one of claims 8 to 12, the thin film is, the wavelength λ M A reflective mask characterized by generating a phase difference of 130 to 230 degrees between the reflected light from the thin film and the reflected light from the multilayer reflective film with respect to light. Claim 15 A method for manufacturing a semiconductor device characterized by using a reflective mask described in any one of claims 8 to 12 and having a process of photolithographically transferring the transfer pattern onto a resist film on a semiconductor substrate.

Images