Reflective mask blank, reflective mask, production method therefor, and semiconductor device production method

Abstract

To provide a reflective mask blank with which it is possible to further reduce a shadowing effect of a reflective mask, and also possible to form a fine and highly accurate phase-shift pattern.SOLUTION: A reflective mask blank has, in the following order on a substrate, a multilayer reflective film and a phase-shift film that shifts a phase of EUV light. The phase-shift film has a thin film composed of a metal-containing material that contains: ruthenium (Ru); and at least one element among chromium (Cr), nickel (Ni), cobalt (Co), aluminum (Al), silicon (Si), titanium (Ti), vanadium (V), germanium (Ge), niobium (Nb), molybdenum (Mo), tin (Sn), tellurium (Te), hafnium (Hf), tungsten (W), and rhenium (Re).SELECTED DRAWING: Figure 1

Description

Technical Field

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

Background Art

[0002] The types of light sources of exposure apparatuses in semiconductor device manufacturing have evolved while gradually shortening the wavelength, such as g-line with a wavelength of 436 nm, i-line with a wavelength of 365 nm, KrF laser with a wavelength of 248 nm, ArF laser with a wavelength of 193 nm, and extreme ultraviolet light (EUV: Extreme Ultra Violet) with a wavelength near 13.5 nm. In order to achieve more fine pattern transfer, EUV lithography using extreme ultraviolet light with a wavelength near 13.5 nm has been developed. In EUV lithography, since there are few materials transparent to EUV light, a reflective mask is used. In this reflective mask, a multilayer reflective film that reflects exposure light is formed on a low thermal expansion substrate, and a mask structure in which a desired transfer pattern is formed is used as a basic structure on a protective film for protecting the multilayer reflective film. Further, from the configuration of the transfer pattern, typical ones include a binary type reflective mask and a phase shift type reflective mask (halftone phase shift type reflective mask). The binary type reflective mask has a relatively thick absorber pattern that sufficiently absorbs EUV light. The phase shift type reflective mask has a relatively thin absorber pattern (phase shift pattern) that attenuates EUV light by light absorption and generates reflected light whose phase is almost inverted (phase inversion of about 180 degrees) with respect to the reflected light from the multilayer reflective film. Similar to the transmissive optical phase shift mask, the phase shift type reflective mask has an effect of improving resolution because a high transfer optical image contrast can be obtained by the phase shift effect. Further, since the film thickness of the absorber pattern (phase shift pattern) of the phase shift type reflective mask is thin, a fine phase shift pattern can be formed with high accuracy.

[0003] In EUV lithography, a projection optical system consisting of a large number of reflectors is used due to the relationship of light transmittance. And EUV light is incident obliquely on the reflective mask so that these multiple reflectors do not block the projection light (exposure light). Currently, the mainstream incident angle is 6 degrees with respect to the plane perpendicular to the reflective mask substrate. Along with the improvement of the numerical aperture (NA) of the projection optical system, studies are underway in the direction of making the incident angle more oblique, about 8 degrees.

[0004] In EUV lithography, since the exposure light is incident obliquely, there is a unique problem called the shadowing effect. The shadowing effect refers to a phenomenon in which when exposure light is incident obliquely on an absorber pattern with a three-dimensional structure, a shadow is formed, and the dimensions and positions of the pattern to be transferred and formed change. The three-dimensional structure of the absorber pattern forms a wall and creates a shadow on the shaded side, changing the dimensions and positions of the pattern to be transferred and formed. For example, when the orientation of the absorber pattern to be arranged is parallel and perpendicular to the direction of the obliquely incident light, there are differences in the dimensions and positions of the two transferred patterns, reducing the transfer accuracy.

[0005] Technologies related to such reflective masks for EUV lithography and mask blanks for fabricating them are disclosed in Patent Documents 1 to 3. Also, Patent Document 1 discloses the shadowing effect. By using a phase shift type reflective mask as a reflective mask for EUV lithography, by making the film thickness of the phase shift pattern relatively thinner than the film thickness of the absorber pattern of the binary type reflective mask, it is possible to suppress the reduction in transfer accuracy due to the shadowing effect.

[0006] [Patent Document 1] Japanese Unexamined Patent Application Publication No. 2010 - 080659 [Patent Document 2] Japanese Unexamined Patent Application Publication No. 2004 - 207593 [Patent Document 3] Japanese Unexamined Patent Application Publication No. 2009 - 206287 [Disclosure of the Invention]

[0007] The finer the pattern and the higher the accuracy of the pattern dimensions and pattern positions, the better the electrical characteristics and performance of the semiconductor device, and the integration density can be increased and the chip size can be reduced. Therefore, EUV lithography is required to have even higher high-precision fine dimension pattern transfer performance than before. Currently, the formation of ultra-fine high-precision patterns corresponding to the hp16nm (half pitch 16nm) generation is required. In response to such requirements, in order to reduce the shadowing effect, it is required to further reduce the film thickness of the absorber film (phase shift film). In particular, in the case of EUV exposure, it is required that the film thickness of the absorber film (phase shift film) be less than 60 nm, preferably 50 nm or less.

[0008] As disclosed in Patent Documents 1 to 3, Ta has been conventionally used as a material for forming the absorber film (phase shift film) of the reflective mask blank. However, the refractive index n of Ta at EUV light (for example, wavelength 13.5 nm) is about 0.943. Therefore, even when utilizing the phase shift effect of Ta, the lower limit of the film thickness of the absorber film (phase shift film) formed only of Ta is 60 nm at the limit. In order to make the film thickness thinner, for example, a metal material with a small refractive index n (large phase shift effect) can be used. As metal materials with a small refractive index n at a wavelength of 13.5 nm, as described in FIG. 7 of Patent Document 1, for example, Mo (n = 0.921) and Ru (n = 0.887) are available. However, Mo is very easily oxidized and there are concerns about its cleaning resistance, and Ru has a low etching rate and is difficult to process and modify.

[0009] In view of the above points, an object of the present invention is to provide a reflective mask blank that can further reduce the shadowing effect of the reflective mask and form a fine and high-precision phase shift pattern, a reflective mask produced thereby, and a method for manufacturing a semiconductor device.

[0010] To solve the above problems, the present invention has the following configuration.

[0011] (Configuration 1) Configuration 1 of the present invention is a reflective mask blank having a multilayer reflective film and a phase shift film for shifting the phase of EUV light on a substrate in this order, wherein the phase shift film is made of a material containing ruthenium (Ru) and a metal containing at least one element selected from chromium (Cr), nickel (Ni), cobalt (Co), aluminum (Al), silicon (Si), titanium (Ti), vanadium (V), germanium (Ge), niobium (Nb), molybdenum (Mo), tin (Sn), tellurium (Te), hafnium (Hf), tungsten (W), and rhenium (Re). It is a reflective mask blank characterized by having a thin film.

[0012] According to Configuration 1 of the present invention, it is possible to obtain a phase shift film in which the film thickness required for the reflected light from the phase shift pattern to obtain a predetermined phase difference is thinner than the reflected light from the opening of the reflective mask pattern. Therefore, in the reflective mask, the shadowing effect caused by the phase shift pattern can be further reduced. Further, according to Configuration 1 of the present invention, a phase shift film with a high relative reflectance (relative reflectance when the EUV light reflected in the portion without the phase shift pattern is set to a reflectance of 100%) can be obtained. As a result, by using the reflective mask manufactured from the reflective mask blank of Configuration 1 of the present invention, the throughput in semiconductor device manufacturing can be improved.

[0013] (Configuration 2) Configuration 2 of the present invention is a reflective mask blank of Configuration 1, characterized in that the crystal structure of the phase shift film is amorphous.

[0014] According to Configuration 2 of the present invention, since the crystal structure of the material constituting the phase shift film is amorphous, the adverse effects of crystal particles such as metals during the formation of the phase shift pattern can be reduced.

[0015] (Configuration 3) According to Configuration 3 of the present invention, the phase shift film is a thin film made of a material containing a metal containing ruthenium (Ru) and at least one element among chromium (Cr), nickel (Ni), and cobalt (Co), and is the reflective mask blank according to Configuration 1 or 2, characterized in that.

[0016] According to Configuration 3 of the present invention, since the etching rate by the dry etching gas when patterning the phase shift film can be increased, the thickness of the resist film can be reduced, which is advantageous for forming a fine pattern of the phase shift film.

[0017] (Configuration 4) According to Configuration 4 of the present invention, the reflective mask blank according to Configuration 3 is characterized in that the composition ratio (Ru:Cr) of the Ru and the Cr is 15:1 to 1:20.

[0018] According to Configuration 4 of the present invention, since the metal used together with Ru is Cr which can be etched by the same etching gas as Ru, and the composition ratio of Ru and Cr is within a predetermined range, good processing characteristics can be obtained, and a phase shift film capable of obtaining a predetermined phase difference can be obtained with a thin film thickness.

[0019] (Configuration 5) According to Configuration 5 of the present invention, the reflective mask blank according to Configuration 3 is characterized in that the composition ratio (Ru:Ni) of the Ru and the Ni is 20:1 to 1:4.

[0020] According to Configuration 5 of the present invention, since the metal used together with Ru is Ni having a large attenuation coefficient, and the composition ratio of Ru and Ni is within a predetermined range, a phase shift film capable of obtaining a predetermined phase difference with a high reflectance can be obtained with a thin film thickness.

[0021] (Configuration 6) According to Configuration 6 of the present invention, the reflective mask blank according to Configuration 3 is characterized in that the composition ratio (Ru:Co) of the Ru and the Co is 20:1 to 1:5.

[0022] According to Configuration 6 of the present invention, since the metal used together with Ru is Co having a large attenuation coefficient and the composition ratio of Ru and Co is within a predetermined range, a phase shift film capable of obtaining a predetermined phase difference with high reflectance at a thin film thickness can be obtained.

[0023] (Configuration 7) Configuration 7 of the present invention further has a protective film between the multilayer reflective film and the phase shift film, and the protective film is a reflective mask blank according to any one of Configurations 1 to 6, characterized in that it is made of a material containing silicon (Si) and oxygen (O).

[0024] According to Configuration 7 of the present invention, since a protective film is formed on the multilayer reflective film, damage to the surface of the multilayer reflective film when manufacturing a reflective mask (EUV mask) using a substrate with a multilayer reflective film can be suppressed, so that the reflectance characteristics with respect to EUV light become good. Since the protective film is made of a material containing silicon (Si) and oxygen (O), it has resistance to the dry etching gas for patterning the phase shift film, so damage to the protective film can be suppressed without etching the protective film.

[0025] (Configuration 8) Configuration 8 of the present invention is a reflective mask characterized in that the phase shift film in any one of Configurations 1 to 7 of the reflective mask blank has a patterned phase shift pattern.

[0026] According to Configuration 8 of the present invention, since the phase shift pattern of the reflective mask absorbs EUV light and can reflect a part of the EUV light with a predetermined phase difference from the opening (the part where the phase shift pattern is not formed), the reflective mask (EUV mask) of the present invention can be manufactured by patterning the phase shift film of the reflective mask blank.

[0027] (Configuration 9) The manufacturing method of the reflective mask according to Configuration 9 of the present invention is characterized in that the phase shift film of any one of Configurations 1 to 7 of the reflective mask blank is patterned with a dry etching gas containing a chlorine-based gas and an oxygen gas to form a phase shift pattern.

[0028] According to Configuration 9 of the present invention, it is possible to reduce the film thickness of the phase shift film, reduce the shadowing effect, and form a fine and highly accurate phase shift pattern with a stable cross-sectional shape having less sidewall roughness, thereby manufacturing a reflective mask.

[0029] (Configuration 10) The manufacturing method of the semiconductor device according to Configuration 10 of the present invention is characterized by having a step of setting the reflective mask of Configuration 8 in an exposure apparatus having an exposure light source that emits EUV light and transferring a transfer pattern onto a resist film formed on a substrate to be transferred.

[0030] According to the manufacturing method of the semiconductor device of Configuration 10 of the present invention, it is possible to reduce the film thickness of the phase shift film, reduce the shadowing effect, and form a fine and highly accurate phase shift pattern with a stable cross-sectional shape having less sidewall roughness, and use the reflective mask for manufacturing the semiconductor device. Therefore, it is possible to manufacture a semiconductor device having a fine and highly accurate transfer pattern.

[0031] According to the reflective mask blank of the present invention (the reflective mask manufactured thereby), it is possible to reduce the film thickness of the phase shift film, reduce the shadowing effect, and form a fine and highly accurate phase shift pattern with a stable cross-sectional shape having less sidewall roughness. Therefore, the reflective mask manufactured using the reflective mask blank of this structure can form the phase shift pattern itself formed on the mask finely and highly accurately, and can prevent the accuracy reduction during transfer due to shadowing. In addition, by performing EUV lithography using this reflective mask, it becomes possible to provide a manufacturing method for a fine and highly accurate semiconductor device.

Brief Description of the Drawings

[0032]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0033] Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings. The following embodiments are one form when embodying the present invention and do not limit the present invention within its scope. In the drawings, the same or corresponding parts may be denoted by the same reference numerals and the description thereof may be simplified or omitted.

[0034] <Configuration and Manufacturing Method of Reflective Mask Blank 100> FIG. 1 is a schematic cross-sectional view of a main part for explaining the configuration of the reflective mask blank 100 of the present embodiment. As shown in FIG. 1, the reflective mask blank 100 has a mask blank substrate 1 (also simply referred to as "substrate 1"), a multilayer reflective film 2, a protective film 3, and a phase shift film 4, which are laminated in this order. The multilayer reflective film 2 reflects EUV light, which is exposure light formed on the first main surface (front surface) side. The protective film 3 is provided to protect the multilayer reflective film 2 and is formed of a material having resistance to an etchant and a cleaning liquid used when patterning the phase shift film 4 described later. The phase shift film 4 absorbs EUV light. Further, a back surface conductive film 5 for an electrostatic chuck is formed on the second main surface (back surface) side of the substrate 1.

[0035] In this specification, "having the multilayer reflective film 2 on the main surface of the substrate 1 for mask blank" means that the multilayer reflective film 2 is disposed in contact with the surface of the substrate 1 for mask blank, and also includes the case where there is another film between the substrate 1 for mask blank and the multilayer reflective film 2. The same applies to other films. For example, "having the film B on the film A" means that the film A and the film B are disposed in direct contact with each other, and also includes the case where there is another film between the film A and the film B. Further, in this specification, for example, "the film A is disposed in contact with the surface of the film B" means that the film A and the film B are disposed in direct contact with each other without another film therebetween.

[0036] In this specification, when the phase shift film 4 is, for example, "a thin film made of a material containing a metal containing ruthenium (Ru) and chromium (Cr)", it means that the phase shift film 4 is a thin film composed of at least a material substantially containing ruthenium (Ru) and chromium (Cr). On the other hand, when the phase shift film 4 is "a thin film composed of ruthenium (Ru) and chromium (Cr)", it may mean that the phase shift film 4 is composed of only ruthenium (Ru) and chromium (Cr). Also, in any case, it includes that inevitable impurities are contained in the phase shift film 4.

[0037] Hereinafter, an explanation will be given for each layer.

[0038] <<Substrate 1>> In order to prevent distortion of the phase shift pattern 4a due to heat during exposure with EUV light, the substrate 1 preferably has a low coefficient of thermal expansion within the range of 0 ± 5 ppb / °C. As a material having a low coefficient of thermal expansion within this range, for example, SiO2-TiO2-based glass, multi-component glass ceramics, etc. can be used.

[0039] The first main surface of the substrate 1 on which the transfer pattern (which is constituted by the phase shift film 4 described later) is formed is surface-treated to have a high flatness from the viewpoints of obtaining at least pattern transfer accuracy and position accuracy. In the case of EUV exposure, in the region of 132 mm × 132 mm on the main surface of the substrate 1 on which the transfer pattern is formed, the flatness is preferably 0.1 μm or less, more preferably 0.05 μm or less, and particularly preferably 0.03 μm or less. Further, the second main surface on the side opposite to the side on which the transfer pattern is formed is the surface that is electrostatically chucked when set in the exposure apparatus, and in the region of 132 mm × 132 mm, the flatness is preferably 0.1 μm or less, more preferably 0.05 μm or less, and particularly preferably 0.03 μm or less. Note that the flatness on the second main surface side of the reflective mask blank 100 is preferably 1 μm or less, more preferably 0.5 μm or less, and particularly preferably 0.3 μm or less in the region of 142 mm × 142 mm.

[0040] Also, the surface smoothness height of the substrate 1 is an extremely important item. The surface roughness of the first main surface of the substrate 1 on which the transfer phase shift pattern 4a is formed is preferably 0.1 nm or less in terms of root mean square roughness (RMS). Note that the surface smoothness can be measured with an atomic force microscope.

[0041] Furthermore, the substrate 1 preferably has high rigidity in order to prevent deformation due to the film stress of the film (such as the multilayer reflective film 2) formed thereon. In particular, it preferably has a high Young's modulus of 65 GPa or more.

[0042] <<Multilayer reflective film 2>> The multilayer reflective film 2 imparts a function of reflecting EUV light in the reflective mask 200, and is a multilayer film in which layers mainly composed of elements with different refractive indices are periodically laminated.

[0043] Generally, a multilayer film in which a thin film of a light element or its compound (high refractive index layer), which is a high refractive index material, and a thin film of a heavy element or its compound (low refractive index layer), which is a low refractive index material, are alternately laminated about 40 to 60 cycles is used as the multilayer reflective film 2. The multilayer film may be laminated with a plurality of cycles with a laminated structure of a high refractive index layer / low refractive index layer in which the high refractive index layer and the low refractive index layer are laminated in this order from the substrate 1 side as one cycle. Also, the multilayer film may be laminated with a plurality of cycles with a laminated structure of a low refractive index layer / high refractive index layer in which the low refractive index layer and the high refractive index layer are laminated in this order from the substrate 1 side as one cycle. Note that the outermost layer of the multilayer reflective film 2, that is, the surface layer on the side opposite to the substrate 1 of the multilayer reflective film 2 is preferably a high refractive index layer. In the above multilayer film, when a plurality of cycles are laminated with a laminated structure of a high refractive index layer / low refractive index layer in which the high refractive index layer and the low refractive index layer are laminated in this order from the substrate 1 as one cycle, the uppermost layer is 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 is easily oxidized and the reflectance of the reflective mask 200 decreases. Therefore, it is preferable to further form a high refractive index layer on the low refractive index layer of the uppermost layer to form the multilayer reflective film 2. On the other hand, in the above multilayer film, when a plurality of cycles are laminated with a laminated structure of a low refractive index layer / high refractive index layer in which the low refractive index layer and the high refractive index layer are laminated in this order from the substrate 1 side as one cycle, since the uppermost layer is a high refractive index layer, it may be left as it is.

[0044] In this embodiment, as the high refractive index layer, a layer containing silicon (Si) is adopted. As the material containing Si, in addition to Si alone, Si compounds containing boron (B), carbon (C), nitrogen (N), and oxygen (O) can be used for Si. By using the Si-containing layer as the high refractive index layer, a reflective mask 200 for EUV lithography excellent in the reflectivity of EUV light can be obtained. Further, in this embodiment, a glass substrate is preferably used as the substrate 1. Si is also excellent in adhesion to the glass substrate. Further, as the low refractive index layer, a single metal selected from molybdenum (Mo), ruthenium (Ru), rhodium (Rh), and platinum (Pt), or an alloy thereof is used. For example, as the multilayer reflective film 2 for EUV light having a wavelength of 13 nm to 14 nm, a Mo / Si periodically laminated film in which a Mo film and a Si film are alternately laminated about 40 to 60 cycles is preferably used. Note that the high refractive index layer, which is the outermost layer of the multilayer reflective film 2, may be formed of silicon (Si).

[0045] The reflectivity of such a multilayer reflective film 2 alone is usually 65% or more, and the upper limit is usually 73%. Note that the film thickness and period of each constituent layer of the multilayer reflective film 2 may be appropriately selected according to the exposure wavelength and are selected to satisfy the Bragg reflection law. In the multilayer reflective film 2, there are a plurality of high refractive index layers and low refractive index layers, respectively, but the film thicknesses of the high refractive index layers and the low refractive index layers do not have to be the same. Further, the film thickness of the Si layer on the outermost surface of the multilayer reflective film 2 can be adjusted within a range that does not reduce the reflectivity. The film thickness of the Si (high refractive index layer) on the outermost surface can be 3 nm to 10 nm.

[0046] The method of forming the multilayer reflective film 2 is known in the art. For example, it can be formed by forming each layer of the multilayer reflective film 2 by the ion beam sputtering method. In the case of the above-described Mo / Si periodic multilayer film, for example, by the ion beam sputtering method, first, a Si film having a thickness of about 4 nm is formed on the substrate 1 using a Si target. Then, a Mo film having a thickness of about 3 nm is formed using a Mo target. Taking this Si film / Mo film as one cycle, 40 to 60 cycles are laminated to form the multilayer reflective film 2 (the outermost layer is a Si layer). Further, 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.

[0047] <<Protective film 3>> In order to protect the multilayer reflective film 2 from dry etching and cleaning in the manufacturing process of the reflective mask 200 described later, a protective film 3 can be formed on or in contact with the surface of the multilayer reflective film 2. It also serves to protect the multilayer reflective film 2 during the black defect correction of the phase shift pattern 4a using an electron beam (EB). Here, FIG. 1 shows the case where the protective film 3 is a single layer, but it can also have a laminated structure of three or more layers. The protective film 3 is formed of a material that is resistant to the etchant and cleaning liquid used when patterning the phase shift film 4. By forming the protective film 3 on the multilayer reflective film 2, damage to the surface of the multilayer reflective film 2 when manufacturing the reflective mask 200 (EUV mask) using the substrate with the multilayer reflective film can be suppressed. Therefore, the reflectance characteristics of the multilayer reflective film 2 with respect to EUV light become good.

[0048] Hereinafter, the case where each of the protective film 3 and the phase shift film 4 is a single layer will be described as an example. When the protective film 3 includes a plurality of layers, in the relationship with the phase shift film 4, the properties of the material of the uppermost layer (the layer in contact with the phase shift film 4) of the protective film 3 become important. When the phase shift film 4 includes a plurality of layers, in the relationship with the protective film 3 (the uppermost layer), the properties of the material of the lowermost layer (the layer in contact with the protective film 3) of the phase shift film 4 become important.

[0049] In the reflective mask blank 100 of the present embodiment, as the material of the protective film 3, a material resistant to the etching gas used for dry-etching for patterning the phase shift film 4 formed on the protective film 3 can be selected.

[0050] For example, when the layer of the phase shift film 4 in contact with the surface of the protective film 3 is a thin film made of a material (a predetermined Ru-based material) containing ruthenium (Ru) and at least one element selected from chromium (Cr), nickel (Ni), cobalt (Co), aluminum (Al), silicon (Si), titanium (Ti), vanadium (V), germanium (Ge), niobium (Nb), molybdenum (Mo), tin (Sn), tellurium (Te), hafnium (Hf), tungsten (W), and rhenium (Re), as the material of the protective film 3, a silicon-based material such as silicon (Si), a material containing silicon (Si) and oxygen (O), a material containing silicon (Si) and nitrogen (N), and a material selected from a chromium-based material containing chromium (Cr) or chromium (Cr) and at least one element selected from oxygen (O), nitrogen (N), and carbon (C) can be used.

[0051] For example, when the layer of the phase shift film 4 in contact with the surface of the protective layer 3 is a thin film made of a material (a predetermined Ru-based material) containing ruthenium (Ru) and at least one element selected from aluminum (Al), silicon (Si), titanium (Ti), niobium (Nb), molybdenum (Mo), tin (Sn), tellurium (Te), hafnium (Hf), tungsten (W), and rhenium (Re), a fluorine-based gas can be used as the dry-etching gas when patterning the phase shift film 4, and the chromium-based material can be selected as the material of the protective film 3.

[0052] For example, when the layer of the phase shift film 4 in contact with the surface of the protective layer 3 is a thin film made of a material (a predetermined Ru-based material) containing ruthenium (Ru) and at least one element among aluminum (Al), silicon (Si), titanium (Ti), germanium (Ge), tin (Sn), and hafnium (Hf), a fluorine-based gas or a chlorine-based gas not containing oxygen can be used as the dry etching gas when patterning the phase shift film 4. In that case, as the material of the protective layer 3, the silicon-based material and the chromium-based material can be selected.

[0053] For example, when the layer of the phase shift film 4 in contact with the surface of the protective film 3 is a material (a predetermined Ru-based material) containing ruthenium (Ru) and at least one element among chromium (Cr), nickel (Ni), and cobalt (Co), or a material (a predetermined Ru-based material) containing ruthenium (Ru) and at least one element among vanadium (V), niobium (Nb), molybdenum (Mo), tungsten (W), and rhenium (Re), a chlorine-based gas containing oxygen can be used as the dry etching gas when patterning the phase shift film 4. In that case, as the material of the protective film 3, a silicon-based material such as silicon (Si), a material containing silicon (Si) and oxygen (O), or a material containing silicon (Si) and nitrogen (N) can be selected. Further, when the phase shift film 4 is composed of a plurality of layers, if the layer of the phase shift film 4 in contact with the surface of the protective film 3 is a thin film other than the predetermined Ru-based material, the material of the protective film 3 can be selected according to the etching characteristics of the material.

[0054] The protective film 3 of the reflective mask blank 100 according to this embodiment is preferably made of a material containing silicon (Si) or a material containing silicon (Si) and oxygen (O) (silicon-based material). A material containing a metal containing ruthenium (Ru) and at least one or more elements among chromium (Cr), nickel (Ni), and cobalt (Co) (predetermined Ru-based material), and a phase shift film 4 of a material containing a metal containing ruthenium (Ru) and at least one or more elements among vanadium (V), niobium (Nb), molybdenum (Mo), tungsten (W), and rhenium (Re) (predetermined ruthenium (Ru)-based material) can be etched by dry etching with a chlorine-based gas containing oxygen or oxygen gas. Silicon-based materials such as silicon (Si), a material containing silicon (Si) and oxygen (O), or a material containing silicon (Si) and nitrogen (N) have resistance to these dry etching gases, and the higher the oxygen content, the greater the resistance. Therefore, the material of the protective film 3 is more preferably silicon oxide (SiO x , 1 ≦ x ≦ 2), even more preferably with a larger x, and particularly preferably SiO2.

[0055] In EUV lithography, since there are few substances transparent to the exposure light, it is not technically easy to use an EUV pellicle to prevent foreign matter from adhering to the mask pattern surface. For this reason, pellicle-free operation without using a pellicle has become mainstream. Also, in EUV lithography, exposure contamination such as carbon film deposition or oxide film growth occurs on the mask due to EUV exposure. Therefore, when an EUV reflective mask is used in the manufacture of semiconductor devices, it is necessary to perform frequent cleaning to remove foreign matter and contamination on the mask. For this reason, EUV reflective masks are required to have mask cleaning resistance far superior to that of transmissive masks for optical lithography. By having the protective film 3 on the reflective mask 200, the cleaning resistance to the cleaning liquid can be increased.

[0056] The film thickness of the protective film 3 is not particularly limited as long as it can fulfill the function of protecting the multilayer reflective film 2. From the viewpoint of the reflectivity of EUV light, the film thickness of the protective film 3 is preferably from 1.0 nm to 8.0 nm, more preferably from 1.5 nm to 6.0 nm.

[0057] As a method for forming the protective film 3, the same as known film formation methods can be adopted without particular limitation. Specific examples include a sputtering method and an ion beam sputtering method.

[0058] <<Phase shift film 4>> On the protective film 3, a phase shift film 4 for shifting the phase of EUV light is formed. In the portion where the phase shift film 4 (phase shift pattern 4a) is formed, while absorbing and reducing the EUV light, a part of the light is reflected at a level that does not adversely affect pattern transfer. On the other hand, in the opening (the portion where the phase shift film 4 is not present), the EUV light is reflected from the multilayer reflective film 2 through the protective film 3. The reflected light from the portion where the phase shift film 4 is formed forms a desired phase difference with the reflected light from the opening. The phase shift film 4 is formed such that the phase difference between the reflected light from the phase shift film 4 and the reflected light from the multilayer reflective film 2 is from 160 degrees to 200 degrees. The light with inverted phase differences near 180 degrees interfere with each other at the pattern edge portion, thereby improving the image contrast of the projection optical image. Along with the improvement of the image contrast, the resolution increases, and various margins related to exposure such as the exposure amount margin and the focus margin expand. Although it depends on the pattern and exposure conditions, generally, the standard of the reflectivity of the phase shift film 4 for obtaining this phase shift effect is 2% or more in relative reflectivity. In order to obtain a sufficient phase shift effect, the reflectivity of the phase shift film 4 is preferably 6% or more in relative reflectivity. Also, when the relative reflectivity is as high as 10% or more, more preferably 15% or more, in order to further improve the contrast, the phase difference can be set to be from 130 degrees to 160 degrees, or from 200 degrees to 230 degrees. Here, the relative reflectivity of the phase shift film 4 (phase shift pattern 4a) is the reflectivity of the EUV light reflected from the phase shift pattern 4a when the reflectivity of the EUV light reflected from the multilayer reflective film 2 (including the multilayer reflective film 2 with the protective film 3) in the portion without the phase shift pattern 4a is set to 100%. In this specification, the relative reflectivity may sometimes be simply referred to as "reflectivity".

[0059] Also, in order to obtain a sufficient phase shift effect, the absolute reflectivity of the phase shift film 4 is preferably 9% or more. Here, the absolute reflectivity of the phase shift film 4 (phase shift pattern 4a) refers to the reflectivity (the ratio of the incident light intensity to the reflected light intensity) of the EUV light reflected from the phase shift film 4 (or the phase shift pattern 4a).

[0060] In order to further improve the resolution and the throughput in manufacturing a semiconductor device, the relative reflectivity of the phase shift pattern 4a is preferably 6% to 40%. More preferably, it is 6 to 35%, still more preferably 15% to 35%, and even more preferably 15% to 25%.

[0061] In order to further improve the resolution and the throughput in manufacturing a semiconductor device, the absolute reflectivity of the phase shift film 4 (or the phase shift pattern 4a) is desirably 4% to 27%, more preferably 10% to 17%.

[0062] The phase shift film 4 of the present embodiment has a thin film made of a material containing a metal containing ruthenium (Ru) and at least one element among chromium (Cr), nickel (Ni), cobalt (Co), aluminum (Al), silicon (Si), titanium (Ti), vanadium (V), germanium (Ge), niobium (Nb), molybdenum (Mo), tin (Sn), tellurium (Te), hafnium (Hf), tungsten (W), and rhenium (Re).

[0063] By using a predetermined material, the phase shift film 4 of the reflective mask blank 100 of the present embodiment can obtain a phase shift pattern 4a having a relative reflectivity of 6% to 40%. By using a predetermined material, the absolute reflectivity of the phase shift film 4 of the reflective mask blank 100 of the present embodiment can be made 4% to 27%. Further, the phase shift film 4 of the reflective mask blank 100 of the present embodiment has a small film thickness necessary for obtaining a predetermined phase difference (the phase difference between the reflected light from the opening and the reflected light from the phase shift pattern 4a). Therefore, in the reflective mask 200, the shadowing effect caused by the phase shift pattern 4a can be further reduced. Further, by using the reflective mask 200 manufactured from the reflective mask blank 100 of the present embodiment, the throughput in manufacturing a semiconductor device can be improved.

[0064] The material of the phase shift film 4 of the reflective mask blank 100 of the present embodiment (hereinafter, may be simply referred to as "predetermined Ru-based material") will be further described.

[0065] The crystal structure of the phase shift film 4 of the reflective mask blank 100 of the present embodiment is preferably amorphous.

[0066] The refractive index n of Ru is n = 0.886 (attenuation coefficient k = 0.017), which is preferable as the material of the high-reflectivity phase shift film 4. However, Ru-based compounds such as RuO tend to have a crystallized structure and also have poor processing characteristics. That is, the crystal grains of the crystallized metal tend to have a large sidewall roughness when forming the phase shift pattern 4a. Therefore, it may have an adverse effect when forming a predetermined phase shift pattern 4a. On the other hand, when the crystal structure of the phase shift film 4 is amorphous, the adverse effect when forming the phase shift pattern 4a can be reduced. By adding a predetermined element (X) to Ru, the crystal structure of the phase shift film 4 can be made amorphous, and at the same time, the etching rate can be increased, the pattern shape can be improved, and the processing characteristics can be improved. As the predetermined element (X), at least one or more of Cr, Ni, Co, Al, Si, Ti, V, Ge, Nb, Mo, Sn, Te, Hf, W, and Re can be selected.

[0067] Note that the refractive index n and attenuation coefficient k of Ni are n = 0.948 and k = 0.073. Also, Co is n = 0.933 and k = 0.066, and Cr is n = 0.932 and k = 0.039. The binary materials (RuCr, RuNi, and RuCo) obtained by adding a predetermined element (X) to Ru can reduce the film thickness of the phase shift film 4 compared to the conventional material RuTa. Also, since Ni and Co have a larger attenuation coefficient k than Cr, selecting Ni and / or Co as the element (X) can reduce the film thickness of the phase shift film 4 more than selecting Cr.

[0068] Also, the refractive index n and extinction coefficient k of Al are n = 1.003 and k = 0.03, the refractive index n and extinction coefficient k of Si are n = 0.999 and k = 0.002, the refractive index n and extinction coefficient k of Ti are n = 0.952 and k = 0.014, the refractive index n and extinction coefficient k of V are n = 0.944 and k = 0.025, the refractive index n and extinction coefficient k of Ge are n = 0.995 and k = 0.032, the refractive index n and extinction coefficient k of Nb are n = 0.933 and k = 0.005, the refractive index n and extinction coefficient k of Mo are n = 0.923 and k = 0.007, the refractive index n and extinction coefficient k of Sn are n = 0.941 and k = 0.074, the refractive index n and extinction coefficient k of Te are n = 0.973 and k = 0.075, the refractive index n and extinction coefficient k of Hf are n = 0.961 and k = 0.035, the refractive index n and extinction coefficient k of W are n = 0.933 and k = 0.033, and the refractive index n and extinction coefficient k of Re are n = 0.914 and k = 0.04.

[0069] Also, Sn, Te, and Re have a larger extinction coefficient k than Cr. Therefore, selecting Sn, Te, and Re as the element (X) makes it possible to reduce the film thickness of the phase shift film 4 compared to selecting Cr.

[0070] In addition, when the phase difference of the phase shift film 4 is in the range of 160 degrees to 200 degrees, the ranges of the refractive index n and the extinction coefficient k are as follows. When the relative reflectance of the phase shift film 4 is 6% to 40% or the absolute reflectance is 4% to 27%, the refractive index n of the material obtained by adding a predetermined element (X) to Ru with respect to EUV light is preferably 0.860 to 0.950, and the extinction coefficient k is preferably 0.008 to 0.095. When the relative reflectance is 6% to 35% or the absolute reflectance is 4% to 23%, the refractive index n of the material obtained by adding a predetermined element (X) to Ru with respect to EUV light is preferably 0.880 to 0.950, and the extinction coefficient k is preferably 0.012 to 0.095. When the relative reflectance is 15% to 35% or the absolute reflectance is 10% to 23%, the refractive index n of the material obtained by adding a predetermined element (X) to Ru with respect to EUV light is preferably 0.880 to 0.950, and the extinction coefficient k is preferably 0.012 to 0.050. When the relative reflectance is 15% to 25% or the absolute reflectance is 10% to 17%, the refractive index n of the material obtained by adding a predetermined element (X) to Ru with respect to EUV light is preferably 0.890 to 0.950, and the extinction coefficient k is preferably 0.020 to 0.050.

[0071] In addition, when the phase difference of the phase shift film 4 is in the range of 130 degrees to 160 degrees, the ranges of the refractive index n and the extinction coefficient k are as follows. When the relative reflectance of the phase shift film 4 is 10% to 40% or the absolute reflectance is 6.7% to 27%, the refractive index n of the material obtained by adding a predetermined element (X) to Ru with respect to EUV light is preferably 0.860 to 0.950, and the extinction coefficient k is preferably 0.009 to 0.095. When the relative reflectance is 15% to 35% or the absolute reflectance is 10% to 23%, the refractive index n of the material obtained by adding a predetermined element (X) to Ru with respect to EUV light is preferably 0.860 to 0.950, and the extinction coefficient k is preferably 0.01 to 0.073.

[0072] In addition, when the phase difference of the phase shift film 4 is in the range of 200 degrees to 230 degrees, the refractive index n and the extinction coefficient k are as follows. When the relative reflectance of the phase shift film 4 is 10% to 40% or the absolute reflectance is 6.7% to 27%, the refractive index n of the material obtained by adding a predetermined element (X) to Ru with respect to EUV light is preferably 0.860 to 0.940, and the extinction coefficient k is preferably 0.008 to 0.057. When the relative reflectance is 15% to 35% or the absolute reflectance is 10% to 23%, the refractive index n of the material obtained by adding a predetermined element (X) to Ru with respect to EUV light is preferably 0.860 to 0.939, and the extinction coefficient k is preferably 0.009 to 0.045.

[0073] The phase difference and reflectance of the phase shift film 4 can be adjusted by changing the refractive index n, the extinction coefficient k, and the film thickness. The film thickness of the phase shift film 4 is preferably 60 nm or less, more preferably 50 nm or less, and even more preferably 40 nm or less. The film thickness of the phase shift film 4 is preferably 25 nm or more. When the protective film 3 is provided, the phase difference and reflectance of the phase shift film 4 can also be adjusted in consideration of the refractive index n, the extinction coefficient k, and the film thickness of the protective film 3.

[0074] The binary materials (RuCr, RuNi, and RuCo) obtained by adding a predetermined element (X) to Ru have better processing characteristics than the conventional material RuTa. When Ta is oxidized, it is difficult to etch with chlorine-based gas and oxygen gas. In particular, RuCr has excellent processing characteristics.

[0075] The binary materials (RuCr, RuNi, and RuCo) obtained by adding a predetermined element (X) to Ru have an amorphous structure and can be easily etched with a mixed gas of chlorine-based gas and oxygen gas. In addition, these materials can be etched with oxygen gas. The same is considered to be true for ternary materials (RuCrNi, RuCrCo, and RuNiCo) and quaternary materials (RuCrNiCo).

[0076] In addition to the above binary materials, binary materials (RuV, RuNb, RuMo, RuW, and RuRe) obtained by adding V, Nb, Mo, W, or Re to Ru have better workability than the conventional material RuTa. Similar to RuCr, RuW and RuMo are particularly excellent in processing characteristics.

[0077] Moreover, binary materials (RuV, RuNb, RuMo, RuW, and RuRe) obtained by adding a predetermined element (X) to Ru have an amorphous structure and can be easily etched with a mixed gas of a chlorine-based gas and oxygen gas. Also, these materials can be etched with oxygen gas. The same is considered to be true for ternary and quaternary materials.

[0078] Next, the mixing ratio of Ru and a predetermined element (X) in a predetermined Ru-based material, which is the material of the phase shift film 4 of the present embodiment, will be described.

[0079] The relative reflectivity and absolute reflectivity of the specified Ru-based material increase as the Ru content increases. Also, the reflected light of the phase shift film 4 is the superposition of the surface reflected light from the surface of the phase shift film 4 and the back surface reflected light at the back surface of the phase shift film 4 (the interface between the phase shift film 4 and the protective film 3 or the multilayer reflection film 2) that has passed through the phase shift film 4. Therefore, the intensity of the reflected light of the phase shift film 4 has a periodic structure that depends on the film thickness of the phase shift film 4. As a result, as shown by an example in FIG. 3, the reflectivity and phase difference of the phase shift film 4 also exhibit a periodic structure that depends on the film thickness. Note that FIG. 3 shows the relationship between the film thickness of the phase shift film 4, the relative reflectivity of EUV light, and the phase difference when the phase shift film 4 is a RuCr film and the atomic ratio of Ru to Cr is Ru:Cr = 56:44. This periodic structure is affected by the refractive index n and extinction coefficient k of the material of the phase shift film 4. On the other hand, the reflected light from the phase shift pattern 4a needs to have a predetermined phase difference (for example, a phase difference of 180 degrees) with respect to the reflected light from the opening. Considering the above comprehensively, as a result of examining the relationship between the relative reflectivity of the phase shift film 4, the composition and film thickness of the specified Ru-based material, as described below, for the composition and film thickness of the specified Ru-based material, a preferable range can be shown according to the relative reflectivity of the phase shift film 4. As shown in FIG. 3, when the phase shift film 4 is formed of a RuCr film (Ru:Cr = 56:44), the film thickness is 32.6 nm, the relative reflectivity with respect to the multilayer reflection film (with a protective film) is 20%, and the phase difference is about 180 degrees. In the above description, the relative reflectivity of the phase shift film 4 can be read as the absolute reflectivity. In FIG. 3, when the phase shift film 4 is formed of a RuCr film (Ru:Cr = 56:44), the film thickness is 32.6 nm, the absolute reflectivity is 13.3%, and the phase difference is about 180 degrees.

[0080] When the material of the phase shift film 4 of the reflective mask blank 100 of the present embodiment contains Ru and Cr, the composition ratio (Ru:Cr) of Ru and Cr is preferably 15:1 to 1:20.

[0081] Specifically, when the material of the phase shift film 4 contains Ru and Cr, the relationships among the relative reflectance of the phase shift film 4, the absolute reflectance of the phase shift film 4, the composition (atomic ratio) of a predetermined Ru-based material, and the film thickness are as follows. That is, when the relative reflectance of the phase shift film 4 is 6% or more (the absolute reflectance is 4% or more), Cr is 20 or less and the film thickness is 50 nm or less when the atomic ratio of Ru is 1. When the relative reflectance of the phase shift film 4 is 15% or more (the absolute reflectance is 10% or more), Cr is 4 or less and the film thickness is 45 nm or less when the atomic ratio of Ru is 1. When the relative reflectance of the phase shift film 4 is 25% or less (the absolute reflectance is 17% or less), Ru is 5 or less and the film thickness is 30 nm or more when the atomic ratio of Cr is 1. When the relative reflectance of the phase shift film 4 is 40% or less (the absolute reflectance is 27% or less), Ru is 15 or less and the film thickness is 25 nm or more when the atomic ratio of Cr is 1.

[0082] When the material of the phase shift film 4 of the reflective mask blank 100 of the present embodiment contains Ru and Ni, the composition ratio (Ru:Ni) of Ru and Ni is preferably 20:1 to 1:4.

[0083] Specifically, when the material of the phase shift film 4 contains Ru and Ni, the relationships among the relative reflectance of the phase shift film 4, the absolute reflectance of the phase shift film 4, the composition (atomic ratio) of a predetermined Ru-based material, and the film thickness are as follows. That is, when the relative reflectance of the phase shift film 4 is 6% or more (the absolute reflectance is 4% or more), Ni is 4 or less and the film thickness is 45 nm or less when the atomic ratio of Ru is 1. When the relative reflectance of the phase shift film 4 is 15% or more (the absolute reflectance is 10% or more), Ni is 1 or less and the film thickness is 45 nm or less when the atomic ratio of Ru is 1. When the relative reflectance of the phase shift film 4 is 25% or less (the absolute reflectance is 17% or less), Ru is 10 or less and the film thickness is 30 nm or more when the atomic ratio of Ni is 1. When the relative reflectance of the phase shift film 4 is 40% or less (the absolute reflectance is 27% or less), Ru is 20 or less and the film thickness is 25 nm or more when the atomic ratio of Ni is 1.

[0084] When the material of the phase shift film 4 of the reflective mask blank 100 of the present embodiment contains Ru and Co, the composition ratio (Ru:Co) of Ru and Co is preferably 20:1 to 1:5.

[0085] Specifically, when the material of the phase shift film 4 contains Ru and Co, the relationship between the relative reflectance of the phase shift film 4, the absolute reflectance of the phase shift film 4, the composition (atomic ratio) of a predetermined Ru-based material, and the film thickness is as follows. That is, when the relative reflectance of the phase shift film 4 is 6% or more (the absolute reflectance is 4% or more), Co is 5 or less when the atomic ratio of Ru is 1, and the film thickness is 40 nm or less. When the relative reflectance of the phase shift film 4 is 15% or more (the absolute reflectance is 10% or more), Co is 1.5 or less when the atomic ratio of Ru is 1, and the film thickness is 40 nm or less. When the relative reflectance of the phase shift film 4 is 25% or less (the absolute reflectance is 17% or less), Ru is 10 or less when the atomic ratio of Co is 1, and the film thickness is 30 nm or more. When the relative reflectance of the phase shift film 4 is 40% or less (the absolute reflectance is 27% or less), Ru is 20 or less when the atomic ratio of Co is 1, and the film thickness is 25 nm or more.

[0086] As described above, when the composition (atomic ratio) of Ru and Cr, Ni, and Co is within a predetermined range, a phase shift film 4 having a high reflectance and a predetermined phase difference can be obtained at a thin film thickness.

[0087] Also, when the phase shift film 4 contains Ru and Al, when it contains Ru and Si, when it contains Ru and Ti, when it contains Ru and V, when it contains Ru and Ge, when it contains Ru and Nb, when it contains Ru and Mo, when it contains Ru and Sn, when it contains Ru and Te, when it contains Ru and Hf, when it contains Ru and W, and when it contains Ru and Re, the relationship between the relative reflectance of the phase shift film 4, the absolute reflectance of the phase shift film 4, the composition (atomic ratio) of a predetermined Ru-based material, and the film thickness is as follows.

[0088] When the material of the phase shift film 4 of the reflective mask blank 100 of the present embodiment contains Ru and Al, the composition ratio of Ru and Al (Ru:Al) is preferably 20:1 to 4:5.

[0089] When the relative reflectivity of the phase shift film 4 is 6% or more (the absolute reflectivity is 4% or more), when the atomic ratio of Ru is 4, Al is 5 or less, and the film thickness is 67 nm or less. When the relative reflectivity of the phase shift film 4 is 15% or more (the absolute reflectivity is 10% or more), when the atomic ratio of Ru is 13, Al is 7 or less, and the film thickness is 50 nm or less. When the relative reflectivity of the phase shift film 4 is 25% or less (the absolute reflectivity is 17% or less), when the atomic ratio of Al is 1, Ru is 4 or less, and the film thickness is 36 nm or more. When the relative reflectivity of the phase shift film 4 is 40% or less (the absolute reflectivity is 27% or less), Ru is 20 or less when the atomic ratio of Al is 1, and the film thickness is 30 nm or more.

[0090] When the material of the phase shift film 4 of the reflective mask blank 100 of the present embodiment contains Ru and Si, the composition ratio of Ru and Si (Ru:Si) is preferably 20:1 to 1:1.

[0091] When the relative reflectivity of the phase shift film 4 is 15% or more (the absolute reflectivity is 10% or more), when the atomic ratio of Ru is 1, Si is 1 or less, and the film thickness is 70 nm or less. When the relative reflectivity of the phase shift film 4 is 40% or less (the absolute reflectivity is 27% or less), Ru is 20 or less when the atomic ratio of Si is 1, and the film thickness is 30 nm or more.

[0092] When the material of the phase shift film 4 of the reflective mask blank 100 of the present embodiment contains Ru and Ti, the composition ratio of Ru and Ti (Ru:Ti) is preferably 20:1 to 1:20.

[0093] When the relative reflectance of the phase shift film 4 is 15% or more (absolute reflectance is 10%), when the atomic ratio of Ru is 1, Ti is 20 or less and the film thickness is 66 nm or less. When the relative reflectance of the phase shift film 4 is 25% or less (absolute reflectance is 17% or less), when the atomic ratio of Ti is 6, Ru is 4 or less and the film thickness is 45 nm or more. When the relative reflectance of the phase shift film 4 is 40% or less (absolute reflectance is 27% or less), when the atomic ratio of Ti is 1, Ru is 20 or less and the film thickness is 30 nm or more.

[0094] When the material of the phase shift film 4 of the reflective mask blank 100 of the present embodiment contains Ru and V, the composition ratio of Ru and V (Ru:V) is preferably 20:1 to 1:20.

[0095] When the relative reflectance of the phase shift film 4 is 6% or more, when the atomic ratio of Ru is 1, V is 20 or less and the film thickness is 55 nm or less. When the relative reflectance of the phase shift film 4 is 15% or more, when the atomic ratio of Ru is 2, V is 7 or less and the film thickness is 47 nm or less. When the relative reflectance of the phase shift film 4 is 25% or less, when the atomic ratio of V is 9, Ru is 11 or less and the film thickness is 37 nm or more. When the relative reflectance of the phase shift film 4 is 40% or less, when the atomic ratio of V is 1, Ru is 20 or less and the film thickness is 30 nm or more.

[0096] When the material of the phase shift film 4 of the reflective mask blank 100 of the present embodiment contains Ru and Ge, the composition ratio of Ru and Ge (Ru:Ge) is preferably 20:1 to 1:1.

[0097] When the relative reflectance of the phase shift film 4 is 6% or more (the absolute reflectance is 4% or more), when the atomic ratio of Ru is 1, Ge is 1 or less and the film thickness is 66 nm or less. When the relative reflectance of the phase shift film 4 is 15% or more (the absolute reflectance is 10% or more), when the atomic ratio of Ru is 7, Ge is 3 or less and the film thickness is 46 nm or less. When the relative reflectance of the phase shift film 4 is 25% or less (the absolute reflectance is 17% or less), when the atomic ratio of Ge is 1, Ru is 5 or less and the film thickness is 38 nm or more. When the relative reflectance of the phase shift film 4 is 40% or less (the absolute reflectance is 27% or less), when the atomic ratio of Ge is 1, Ru is 20 or less and the film thickness is 31 nm or more.

[0098] When the material of the phase shift film 4 of the reflective mask blank 100 of the present embodiment contains Ru and Nb, the composition ratio of Ru and Nb (Ru:Nb) is preferably 20:1 to 5:1.

[0099] When the relative reflectance of the phase shift film 4 is 15% or more (the absolute reflectance is 10% or more), when the atomic ratio of Ru is 20, Nb is 1 or more and the film thickness is 30 nm or more. When the relative reflectance of the phase shift film 4 is 40% or less (the absolute reflectance is 27% or less), when the atomic ratio of Nb is 1, Ru is 5 or more and the film thickness is 32 nm or less.

[0100] When the material of the phase shift film 4 of the reflective mask blank 100 of the present embodiment contains Ru and Mo, the composition ratio of Ru and Mo (Ru:Mo) is preferably 20:1 to 4:1.

[0101] When the relative reflectance of the phase shift film 4 is 15% or more (the absolute reflectance is 10% or more), when the atomic ratio of Ru is 20, Mo is 1 or more and the film thickness is 30 nm or more. When the relative reflectance of the phase shift film 4 is 40% or less (the absolute reflectance is 27% or less), when the atomic ratio of Mo is 1, Ru is 4 or more and the film thickness is 33 nm or less.

[0102] When the material of the phase shift film 4 of the reflective mask blank 100 of the present embodiment contains Ru and Sn, the composition ratio of Ru and Sn (Ru:Sn) is preferably 20:1 to 3:2.

[0103] When the relative reflectivity of the phase shift film 4 is 6% or more (the absolute reflectivity is 4% or more), when the atomic ratio of Ru is 3, Sn is 2 or less, and the film thickness is 39 nm or less. When the relative reflectivity of the phase shift film 4 is 15% or more (the absolute reflectivity is 10% or more), when the atomic ratio of Ru is 4, Sn is 1 or less, and the film thickness is 33 nm or less. When the relative reflectivity of the phase shift film 4 is 25% or less (the absolute reflectivity is 17% or less), when the atomic ratio of Sn is 2, Ru is 23 or less, and the film thickness is 31 nm or more. When the relative reflectivity of the phase shift film 4 is 40% or less (the absolute reflectivity is 27% or less), when the atomic ratio of Sn is 1, Ru is 20 or less, and the film thickness is 30 nm or more.

[0104] When the material of the phase shift film 4 of the reflective mask blank 100 of the present embodiment contains Ru and Te, the composition ratio of Ru and Te (Ru:Te) is preferably 20:1 to 3:1.

[0105] When the relative reflectivity of the phase shift film 4 is 6% or more (the absolute reflectivity is 4% or more), when the atomic ratio of Ru is 3, Te is 1 or less, and the film thickness is 40 nm or less. When the relative reflectivity of the phase shift film 4 is 15% or more (the absolute reflectivity is 10% or more), when the atomic ratio of Ru is 8, Te is 1 or less, and the film thickness is 33 nm or less. When the relative reflectivity of the phase shift film 4 is 25% or less (the absolute reflectivity is 17% or less), when the atomic ratio of Te is 1, Ru is 15 or less, and the film thickness is 31 nm or more. When the relative reflectivity of the phase shift film 4 is 40% or less (the absolute reflectivity is 27% or less), when the atomic ratio of Te is 1, Ru is 20 or less, and the film thickness is 30 nm or more.

[0106] When the material of the phase shift film 4 of the reflective mask blank 100 of the present embodiment contains Ru and Hf, the composition ratio of Ru and Hf (Ru:Hf) is preferably 20:1 to 1:2.

[0107] When the relative reflectance of the phase shift film 4 is 6% or more (the absolute reflectance is 4% or more), when the atomic ratio of Ru is 1, Hf is 2 or less and the film thickness is 58 nm or less. When the relative reflectance of the phase shift film 4 is 15% or more (the absolute reflectance is 10% or more), when the atomic ratio of Ru is 16, Hf is 9 or less and the film thickness is 40 nm or less. When the relative reflectance of the phase shift film 4 is 25% or less (the absolute reflectance is 17% or less), when the atomic ratio of Hf is 9, Ru is 41 or less and the film thickness is 32 nm or more. When the relative reflectance of the phase shift film 4 is 40% or less (the absolute reflectance is 27% or less), when the atomic ratio of Hf is 1, Ru is 20 or less and the film thickness is 30 nm or more.

[0108] When the material of the phase shift film 4 of the reflective mask blank 100 of the present embodiment contains Ru and W, the composition ratio of Ru and W (Ru:W) is preferably 20:1 to 1:20.

[0109] When the relative reflectance of the phase shift film 4 is 6% or more (the absolute reflectance is 4% or more), when the atomic ratio of Ru is 1, W is 20 or less and the film thickness is 46 nm or less. When the relative reflectance of the phase shift film 4 is 15% or more (the absolute reflectance is 10% or more), when the atomic ratio of Ru is 17, W is 33 or less and the film thickness is 39 nm or less. When the relative reflectance of the phase shift film 4 is 25% or less (the absolute reflectance is 17% or less), when the atomic ratio of W is 7, Ru is 13 or less and the film thickness is 32 nm or more. When the relative reflectance of the phase shift film 4 is 40% or less (the absolute reflectance is 27% or less), when the atomic ratio of W is 1, Ru is 20 or less and the film thickness is 30 nm or more.

[0110] When the material of the phase shift film 4 of the reflective mask blank 100 of the present embodiment contains Ru and Re, the composition ratio of Ru and Re (Ru:Re) is preferably 20:1 to 1:20.

[0111] When the relative reflectance of the phase shift film 4 is 6% or more (absolute reflectance is 4% or more), when the atomic ratio of Ru is 1, Re is 20 or less and the film thickness is 38 nm or less. When the relative reflectance of the phase shift film 4 is 15% or more (absolute reflectance is 10% or more), when the atomic ratio of Ru is 9, Re is 16 or less and the film thickness is 33 nm or less. When the relative reflectance of the phase shift film 4 is 25% or less (absolute reflectance is 17% or less), when the atomic ratio of Re is 9, Ru is 16 or less and the film thickness is 32 nm or more. When the relative reflectance of the phase shift film 4 is 40% or less (absolute reflectance is 27% or less), when the atomic ratio of Re is 1, Ru is 20 or less and the film thickness is 29 nm or more.

[0112] As described above, by having the composition (atomic ratio) of Ru and Al, Si, Ti, V, Ge, Nb, Mo, Sn, Te, Hf, W or Re within a predetermined range, a phase shift film 4 with high reflectance and a predetermined phase difference can be obtained at a thin film thickness.

[0113] In the above description, mainly, a predetermined Ru-based binary system material was described. However, ternary system materials (for example, RuCrNi, RuCrCo, RuNiCo, and RuCrW) and quaternary system materials (for example, RuCrNiCo and RuCrCoW) also have the same properties as the predetermined Ru-based binary system material. Therefore, ternary system or quaternary system materials can be used as the predetermined Ru-based material.

[0114] A predetermined Ru-based material, which is the material of the phase shift film 4, can contain Ru, at least one element selected from Cr, Ni, Co, Al, Si, Ti, V, Ge, Nb, Mo, Sn, Te, Hf, W, and Re, and still other elements, as long as it does not significantly affect the refractive index and extinction coefficient. The predetermined Ru-based material can contain elements such as nitrogen (N), oxygen (O), carbon (C), or boron (B). For example, when nitrogen (N) is added to the predetermined Ru-based material, oxidation of the phase shift film 4 can be suppressed, so that the properties of the phase shift film 4 can be stabilized. Also, when nitrogen (N) is added to the predetermined Ru-based material, it is possible to easily make the crystal state amorphous regardless of the film formation conditions of sputtering. In this case, the nitrogen content is preferably 1 atomic % or more, more preferably 3 atomic % or more. Also, the nitrogen content is preferably 10 atomic % or less. For oxygen (O), carbon (C), boron (B), etc., they can be added to the material of the phase shift film 4 as long as they do not significantly affect the refractive index and extinction coefficient for the purpose of stabilizing the phase shift film 4 or the like. When the material of the phase shift film 4 contains Ru, at least one element selected from Cr, Ni, Co, Al, Si, Ti, V, Ge, Nb, Mo, Sn, Te, Hf, W, and Re, and still other elements, the content of the still other elements is preferably 10 atomic % or less, more preferably 5 atomic % or less.

[0115] The above-mentioned phase shift film 4 of the predetermined Ru-based material can be formed by a known method such as a magnetron sputtering method such as a DC sputtering method and an RF sputtering method. Also, as the target, an alloy target of Ru and at least one element selected from Cr, Ni, Co, Al, Si, Ti, V, Ge, Nb, Mo, Sn, Te, Hf, W, and Re can be used.

[0116] Further, as targets, a Ru target and a Cr target, Ni target, Co target, Al target, Si target, Ti target, V target, Ge target, Nb target, Mo target, Sn target, Te target, Hf target, W target, and / or Re target are used, whereby film formation can be performed as coarse patterning. Coarse patterning has the advantage of easily adjusting the composition ratio of metal elements. However, compared with an alloy target, the crystal state of the film may easily become a columnar structure. By forming a film so as to contain nitrogen (N) in the film during sputtering, the crystal state can be made amorphous.

[0117] The phase shift film 4 may be a single-layer film containing only a film of a predetermined Ru-based material, or may be a multilayer film composed of two or more films. In the case of a single-layer film, there is a feature that the number of steps during mask blank manufacturing can be reduced and the production efficiency is increased. When the phase shift film 4 is a single-layer film that substantially does not contain oxygen, such as a film of a predetermined Ru-based material, a natural oxide film is formed on the surface layer when the formed phase shift film 4 is exposed to the atmosphere. In this case, it is preferable to remove the natural oxide film with a fluorine-based gas and then perform etching with a chlorine-based gas.

[0118] Further, since EUV light has a short wavelength, the film thickness dependencies of the phase difference and reflectance tend to be large. Therefore, stability of the phase difference and reflectance with respect to film thickness variations of the phase shift film 4 is required. However, as shown in FIG. 3, the phase difference and reflectance each show an oscillatory structure with respect to the film thickness of the phase shift film 4. Since the oscillatory structures of the phase difference and reflectance are different, it is difficult to set the film thickness that simultaneously stabilizes the phase difference and reflectance.

[0119] Therefore, even when the film thickness of the phase shift film 4 fluctuates slightly with respect to the design value (for example, within a range of ±0.5% with respect to the designed film thickness), for the phase difference, the variation in the phase difference between surfaces is within a range of a predetermined phase difference of ±2 degrees (for example, when the phase difference is 180 degrees, within a range of 180 degrees ±2 degrees), and for the reflectance, the variation in the reflectance between surfaces is within a range of a predetermined reflectance of ±0.2% (for example, when the relative reflectance is 6%, within a range of 6% ±0.2%). When the phase shift film 4 is a multilayer film, it becomes easier to control the variation in the phase difference and the reflectance between surfaces within a predetermined range. Thus, by forming the phase shift film 4 as a multilayer film, it becomes possible to add various functions to each layer.

[0120] When the phase shift film 4 is formed by an uppermost layer and a lower layer other than the uppermost layer, by suppressing the reflected light of EUV light from the surface of the uppermost layer, it becomes possible to smooth the vibration structure and obtain a stable phase difference and reflectance with respect to film thickness variation. As such a material for the uppermost layer, a silicon compound or a tantalum compound having a refractive index larger than that of the lower layer of the phase shift film 4 is preferable. Examples of the silicon compound include materials containing Si and at least one element selected from N, O, C, and H, preferably SiO2, SiON, and Si3N4. Examples of the tantalum compound include materials containing Ta and at least one element selected from N, O, C, H, and B, preferably materials containing Ta and O. The film thickness of the uppermost layer is preferably 10 nm or less, more preferably 1 to 6 nm, and even more preferably 3 to 5 nm. When the lower layer is a RuCr film, for example, the uppermost layer can be an SiO2 film or a Ta2O5 film.

[0121] The phase shift film 4 of a predetermined ruthenium (Ru)-based material, which is a material containing a metal including Ru and at least one element among Cr, Ni, Co, V, Nb, Mo, W, and Re, can be etched by dry etching using a chlorine-based gas containing oxygen or oxygen gas. Further, the phase shift film 4 of a predetermined ruthenium (Ru)-based material, which is a material containing a metal including Ru and at least one element among Al, Si, Ti, Ge, Sn, and Hf, can be etched by dry etching using a chlorine-based gas not containing oxygen. As the chlorine-based gas, Cl2, SiCl4, CHCl3, CCl4, BCl3, etc. can be used. These etching gases can contain an inert gas such as He and / or Ar as necessary.

[0122] Furthermore, the phase shift film 4 of a predetermined ruthenium (Ru)-based material, which is a metal containing Ru and at least one element among Al, Si, Ti, Nb, Mo, Sn, Te, Hf, W, and Re, can be dry-etched with a fluorine-based gas. As the fluorine-based gas, CF4, CHF3, C2F6, C3F6, C4F6, C4F8, CH2F2, C3F8, and / or SF6, etc. can be used. These etching gases may be used alone or may be a mixed gas of two or more selected from the above fluorine-based gases. Also, as necessary, they can contain an inert gas such as He and / or Ar or O2 gas.

[0123] <<Etching mask film>> An etching mask film can be formed on the phase shift film 4 or in contact with the surface of the phase shift film 4. As the material of the etching mask film, a material is used such that the etching selectivity of the phase shift film 4 with respect to the etching mask film becomes high. Here, the "etching selectivity of B with respect to A" refers to the ratio of the etching rates of A, which is the layer that is not desired to be etched (the masking layer), and B, which is the layer that is desired to be etched. Specifically, it is specified by the formula "etching selectivity of B with respect to A = etching rate of B / etching rate of A". Also, "high selectivity" means that the value of the selectivity defined above is large with respect to the comparison target. The etching selectivity of the phase shift film 4 with respect to the etching mask film is preferably 1.5 or more, and more preferably 3 or more.

[0124] The phase shift film 4 of a predetermined ruthenium (Ru)-based material, which is a material containing a metal containing Ru and at least one element among Cr, Ni, Co, V, Nb, Mo, W, and Re, can be etched by dry etching with a chlorine-based gas containing oxygen or oxygen gas. As a material having a high etching selectivity of the phase shift film 4 of the predetermined ruthenium (Ru)-based material with respect to the etching mask film, a material of silicon or a silicon compound, or a tantalum (Ta)-based material can be used.

[0125] Examples of the silicon compound that can be used for the etching mask film include materials containing Si and at least one element selected from N, O, C, and H, and materials such as metal silicon (metal silicide) or metal silicon compound (metal silicide compound) containing a metal in silicon or a silicon compound. Examples of the metal silicon compound include materials containing a metal and Si and at least one element selected from N, O, C, and H.

[0126] Examples of tantalum (Ta)-based materials that can be used as an etching mask film include materials containing tantalum (Ta) and one or more elements selected from oxygen (O), nitrogen (N), carbon (C), boron (B), and hydrogen (H). Among these, it is particularly preferable to use a material containing tantalum (Ta) and oxygen (O) as the material for the etching mask film. Specific examples of such materials include tantalum oxide (TaO), tantalum oxynitride (TaON), tantalum borate oxide (TaBO), and tantalum borate oxynitride (TaBON).

[0127] In addition, a phase shift film 4 of a predetermined ruthenium (Ru)-based material, which is a material containing Ru and at least one element selected from Al, Si, Ti, Ge, Sn, and Hf, can be etched by dry etching with a chlorine-based gas that does not contain oxygen. As a material having a high etching selectivity of the phase shift film 4 of the predetermined ruthenium (Ru)-based material with respect to the etching mask film, a material of silicon or a silicon compound can be used. Examples of silicon-based compounds include materials containing Si and at least one element selected from N, O, C, and H, and materials such as metal silicon (metal silicide) or metal silicon compound (metal silicide compound) containing a metal in silicon or a silicon compound. Examples of metal silicon compounds include materials containing a metal and Si and at least one element selected from N, O, C, and H.

[0128] Furthermore, a phase shift film 4 of a predetermined ruthenium (Ru)-based material, which is a metal containing Ru and at least one element selected from Al, Si, Ti, Nb, Mo, Sn, Te, Hf, W, and Re, can be dry-etched with a fluorine-based gas.

[0129] Also, when the phase shift film 4 is composed of multiple layers and the uppermost layer of the phase shift film 4 is etched with a fluorine-based gas, a material of chromium or a chromium compound can be used as the material for the etching mask film. Examples of chromium compounds include materials containing Cr and at least one element selected from N, O, C, and H.

[0130] The film thickness of the etching mask film is desirably 3 nm or more from the viewpoint of obtaining the function as an etching mask for accurately forming a transfer pattern on the phase shift film 4. Further, the film thickness of the etching mask film is desirably 15 nm or less from the viewpoint of reducing the film thickness of the resist film 11.

[0131] <<Backside conductive film 5>> On the second main surface (back surface) side of the substrate 1 (the side opposite to the multilayer reflection film 2 formation surface), generally, a backside conductive film 5 for an electrostatic chuck is formed. The electrical property (sheet resistance) required for the backside conductive film 5 for an electrostatic chuck is usually 100 Ω / □ (Ω / Square) or less. The backside conductive film 5 can be formed, for example, by a magnetron sputtering method or an ion beam sputtering method using a target of a metal and an alloy such as chromium and tantalum.

[0132] The material containing chromium (Cr) of the backside conductive film 5 is preferably a Cr compound containing Cr and further containing at least one selected from boron, nitrogen, oxygen, and carbon. Examples of the Cr compound include CrN, CrON, CrCN, CrCO, CrCON, CrBN, CrBON, CrBCN, and CrBOCN.

[0133] As the material containing tantalum (Ta) of the backside conductive film 5, 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. Examples of the Ta compound include TaB, TaN, TaO, TaON, TaCON, TaBN, TaBO, TaBON, TaBCON, TaHf, TaHfO, TaHfN, TaHfON, TaHfCON, TaSi, TaSiO, TaSiN, TaSiON, and TaSiCON.

[0134] As the material containing tantalum (Ta) or chromium (Cr), it is preferable that the nitrogen (N) present on its surface layer is less. Specifically, the nitrogen content in the surface layer of the back surface conductive film 5 of the material containing tantalum (Ta) or chromium (Cr) is preferably less than 5 atomic%, and more preferably contains substantially no nitrogen in the surface layer. This is because in the back surface conductive film 5 of the material containing tantalum (Ta) or chromium (Cr), the lower the nitrogen content in the surface layer, the higher the wear resistance.

[0135] The back surface conductive film 5 is preferably made of a material containing tantalum and boron. By making the back surface conductive film 5 made of a material containing tantalum and boron, a back surface conductive film 5 having wear resistance and chemical solution resistance can be obtained. When the back surface conductive film 5 contains tantalum (Ta) and boron (B), the B content is preferably 5 to 30 atomic%. The ratio (Ta:B) of Ta and B in the sputtering target used for forming the back surface conductive film 5 is preferably 95:5 to 70:30.

[0136] The thickness of the back surface conductive film 5 is not particularly limited as long as it satisfies the function as an electrostatic chuck. The thickness of the back surface conductive film 5 is usually from 10 nm to 200 nm. Further, this back surface conductive film 5 also serves to adjust the stress on the second main surface side of the mask blank 100, and is adjusted so as to balance the stress from various films formed on the first main surface side to obtain a flat reflective mask blank 100.

[0137] <Reflective mask 200 and method for manufacturing the same> This embodiment is a reflective mask 200 having a phase shift pattern 4a in which the phase shift film 4 of the above-described reflective mask blank 100 is patterned. The phase shift pattern 4a can be formed by patterning the phase shift film 4 of the above-described reflective mask blank 100 with a predetermined dry etching gas (for example, a dry etching gas containing a chlorine-based gas and an oxygen gas). The phase shift pattern 4a of the reflective mask 200 can absorb EUV light and reflect a part of the EUV light with a predetermined phase difference (for example, 180 degrees) from the opening (the portion where the phase shift pattern is not formed). As the predetermined dry etching gas, a chlorine-based gas and an oxygen gas, a chlorine-based gas, a fluorine-based gas and an oxygen gas, etc. can be used. In order to pattern the phase shift film 4, an etching mask film may be provided on the phase shift film 4 as necessary, and the phase shift film 4 may be dry-etched using the etching mask film pattern as a mask to form the phase shift pattern 4a.

[0138] A method for manufacturing the reflective mask 200 using the reflective mask blank 100 of this embodiment will be described. Here, only an outline description will be given, and it will be described in detail with reference to the drawings in the examples later.

[0139] Prepare the reflective mask blank 100, and form a resist film 11 on the phase shift film 4 on the first main surface thereof (not necessary if the resist film 11 is provided as the reflective mask blank 100). A desired pattern is drawn (exposed) on this resist film 11, and a predetermined resist pattern 11a is formed by further developing and rinsing.

[0140] In the case of the reflective mask blank 100, the phase shift film 4 is etched using this resist pattern 11a as a mask to form the phase shift pattern 4a, and the resist pattern 11a is removed by ashing or a resist stripping solution, etc., whereby the phase shift pattern 4a is formed. Finally, wet cleaning using an acidic or alkaline aqueous solution is performed.

[0141] The etching gas for the phase shift film 4 is appropriately selected according to a predetermined Ru-based material. For example, when the material of the phase shift film 4 is a material containing Ru and at least one element among Cr, Ni, Co, V, Nb, Mo, W, and Re, as the etching gas for the phase shift film 4, a chlorine-based gas containing oxygen or oxygen gas is used. Since the protective film 3 is made of silicon (Si) or a material containing silicon (Si) and oxygen (O), the surface of the protective film 3 does not become rough during the etching of the phase shift film 4.

[0142] Also, when the material of the phase shift film 4 is a material containing Ru and at least one element among Al, Si, Ti, Ge, Sn, and Hf, as the etching gas for the phase shift film 4, a fluorine-based gas or a chlorine-based gas not containing oxygen gas is used. In this case, by appropriately selecting the material of the protective film 3 from silicon-based materials such as silicon (Si), materials containing silicon (Si) and oxygen (O), or materials containing silicon (Si) and nitrogen (N), and chromium (Cr) or chromium-based materials containing at least one element among oxygen (O), nitrogen (N), and carbon (C), the surface of the protective film 3 does not become rough during the etching of the phase shift film 4.

[0143] Through the above steps, a reflective mask 200 having a high-precision fine pattern with less shadowing effect and less sidewall roughness can be obtained.

[0144] <Method for manufacturing a semiconductor device> This embodiment is a method for manufacturing a semiconductor device. By setting the reflective mask 200 of this embodiment in an exposure apparatus having an EUV light exposure light source and transferring a transfer pattern to a resist film formed on a substrate to be transferred, a semiconductor device can be manufactured.

[0145] Specifically, by performing EUV exposure using the reflective mask 200 of the present embodiment, a desired transfer pattern based on the phase shift pattern 4a on the reflective mask 200 can be formed on the semiconductor substrate while suppressing a decrease in transfer dimension accuracy due to the shadowing effect. Further, since the phase shift pattern 4a is a fine and highly accurate pattern with little sidewall roughness, a desired pattern can be formed on the semiconductor substrate with high dimension accuracy. In addition to this lithography process, a semiconductor device having a desired electronic circuit formed thereon can be manufactured by going through various processes such as etching of the film to be processed, formation of insulating and conductive films, introduction of dopants, and annealing.

[0146] More specifically, the EUV exposure apparatus is composed of a laser plasma light source that generates EUV light, an illumination optical system, a mask stage system, a reduction projection optical system, a wafer stage system, and a vacuum facility, etc. The light source is equipped with a debris trap function, a cut filter that cuts light with wavelengths other than the exposure light, and facilities for vacuum differential exhaust, etc. The illumination optical system and the reduction projection optical system are composed of reflective mirrors. The reflective mask 200 for EUV exposure is electrostatically adsorbed by the back surface conductive film 5 formed on its second main surface and placed on the mask stage.

[0147] The light from the EUV light source is irradiated onto the reflective mask 200 at an angle inclined from 6 degrees to 8 degrees with respect to the vertical plane of the reflective mask 200 through the illumination optical system. The reflected light from the reflective mask 200 with respect to this incident light is reflected (specular reflection) in the opposite direction to the incident direction and at the same angle as the incident angle, and is usually guided to a reflective projection optical system having a reduction ratio of 1 / 4, and exposure is performed on the resist on the wafer (semiconductor substrate) placed on the wafer stage. During this time, at least the places where EUV light passes are evacuated. Also, in this exposure, scanning exposure in which the mask stage and the wafer stage are scanned in synchronization at a speed corresponding to the reduction ratio of the reduction projection optical system and exposure is performed through a slit is the mainstream. By developing this exposed resist film, a resist pattern can be formed on the semiconductor substrate. In the present embodiment, a mask having a thin film with a small shadowing effect and a high-precision phase shift pattern with little sidewall roughness is used. For this reason, the resist pattern formed on the semiconductor substrate becomes a desired one with high dimensional accuracy. By using this resist pattern as a mask and performing etching or the like, for example, a predetermined wiring pattern can be formed on the semiconductor substrate. Through such an exposure process, a processed film processing process, a formation process of an insulating film or a conductive film, a dopant introduction process, or an annealing process or other necessary processes, a semiconductor device is manufactured.

[0148] According to the method for manufacturing a semiconductor device of the present embodiment, the thickness of the phase shift film 4 can be made thin, the shadowing effect can be reduced, and a fine and high-precision phase shift pattern 4a can be formed in a stable cross-sectional shape with little sidewall roughness. The reflective mask 200 can be used for manufacturing a semiconductor device. Therefore, a semiconductor device having a fine and high-precision transfer pattern can be manufactured.

Example

[0149] Hereinafter, examples will be described with reference to the drawings. The present embodiment is not limited to these examples. Note that the same reference numerals are used for the same components in the examples, and the description is simplified or omitted.

[0150] [Example 1] FIG. 2 is a schematic cross-sectional view of a main part showing the process of manufacturing the reflective mask 200 from the reflective mask blank 100.

[0151] The reflective mask blank 100 includes a back surface conductive film 5, a substrate 1, a multilayer reflective film 2, a protective film 3, and a phase shift film 4. The phase shift film 4 of Example 1 is made of a material containing RuCr. Then, as shown in FIG. 2(a), a resist film 11 is formed on the phase shift film 4.

[0152] First, the reflective mask blank 100 of Example 1 will be described.

[0153] A SiO2-TiO2-based glass substrate with a size of 6025 (about 152 mm × 152 mm × 6.35 mm) and both main surfaces of the first main surface and the second main surface polished was prepared as the substrate 1. Polishing consisting of a rough polishing process, a precision polishing process, a local processing process, and a touch polishing process was performed so as to obtain a flat and smooth main surface.

[0154] On the second main surface (back surface) of the SiO2-TiO2-based glass substrate 1, a back surface conductive film 5 made of a CrN film was formed under the following conditions by magnetron sputtering (reactive sputtering). Formation conditions of the back surface conductive film 5: Cr target, mixed gas atmosphere of Ar and N2 (Ar: 90%, N: 10%), film thickness 20 nm.

[0155] Next, a multilayer reflective film 2 was formed on the main surface (first main surface) of the substrate 1 on the side opposite to the side where the back conductive film 5 was formed. The multilayer reflective film 2 formed on the substrate 1 was a periodic multilayer reflective film composed of Mo and Si in order to be a multilayer reflective film 2 suitable for EUV light with a wavelength of 13.5 nm. The multilayer reflective film 2 was formed by alternately laminating Mo layers and Si layers on the substrate 1 by an ion beam sputtering method in an Ar gas atmosphere using a Mo target and a Si target. First, a Si film was formed to a film thickness of 4.2 nm, and then a Mo film was formed to a film thickness of 2.8 nm. This was taken as one cycle, and in the same manner, 40 cycles were laminated. Finally, a Si film was formed to a film thickness of 4.0 nm to form the multilayer reflective film 2. Here, 40 cycles were used, but it is not limited to this, and for example, 60 cycles may be used. When 60 cycles are used, the number of processes increases compared to 40 cycles, but the reflectivity for EUV light can be increased.

[0156] Subsequently, in an Ar gas atmosphere, a protective film 3 made of a SiO2 film was formed to a film thickness of 2.5 nm on the surface of the multilayer reflective film 2 by an RF sputtering method using a SiO2 target.

[0157] Next, a phase shift film 4 made of a RuCr film was formed by a DC magnetron sputtering method. The RuCr film was formed to a film thickness of 45.0 nm in an Ar gas atmosphere using a RuCr target. The content ratio (atomic ratio) of the RuCr film was Ru:Cr = 7:93. When the crystal structure of the RuCr film was measured by an X-ray diffractometer (XRD), the RuCr film had an amorphous structure.

[0158] The refractive index n and extinction coefficient (imaginary part of the refractive index) k of the RuCr film of Example 1 formed as described above at a wavelength of 13.5 nm were as follows. RuCr film: n = 0.929, k = 0.037

[0159] The relative reflectance of the phase shift film 4 made of the above RuCr film at a wavelength of 13.5 nm was 6% (the absolute reflectance was 4%). Also, the film thickness of the phase shift film 4 was 45.0 nm. This film thickness is the film thickness corresponding to a phase difference of 180 degrees when the phase shift film 4 is patterned. It was possible to make it approximately 31% thinner than the film thickness of 65 nm of the TaN film as the phase shift film 4 in Comparative Example 1 described later.

[0160] Next, using the above reflective mask blank 100, a reflective mask 200 was manufactured.

[0161] As described above, a resist film 11 was formed with a thickness of 100 nm on the phase shift film 4 of the reflective mask blank 100 (Fig. 2(a)). Then, a desired pattern was drawn (exposed) on this resist film 11, and a predetermined resist pattern 11a was formed by further developing and rinsing (Fig. 2(b)). Next, using the resist pattern 11a as a mask, dry etching of the RuCr film (phase shift film 4) was performed using a mixed gas of Cl2 gas and O2 gas (gas flow rate ratio Cl2:O2 = 4:1) to form a phase shift pattern 4a (Fig. 2(c)).

[0162] Thereafter, the resist pattern 11a was removed with ashing or a resist stripper solution. Finally, wet cleaning using pure water (DIW) was performed to manufacture the reflective mask 200 (Fig. 2(d)). Note that, if necessary, mask defect inspection can be performed after wet cleaning, and mask defect correction can be appropriately performed.

[0163] In the reflective mask 200 of Example 1, since the phase shift film 4 is made of a RuCr material, the processability with a mixed gas of Cl2 gas and O2 gas is good, and the phase shift pattern 4a could be formed with high precision. Also, the film thickness of the phase shift pattern 4a was 45.0 nm, which could be made thinner than the absorber film formed of a conventional Ta-based material, and the shadowing effect could be reduced compared to Comparative Example 1.

[0164] In addition, the reflective mask 200 fabricated in Example 1 had high transfer accuracy with little LER and in-plane dimensional variation of the transferred resist pattern because the sidewall roughness of the phase shift pattern 4a was small and the cross-sectional shape was stable. Moreover, as described above, since the relative reflectance of the phase shift surface (reflectance with respect to the reflectance of the multilayer reflective film surface with a protective film) was 6% (absolute reflectance was 4%), a sufficient phase shift effect was obtained, and EUV exposure with a high exposure margin and focus margin could be performed.

[0165] The reflective mask 200 fabricated in Example 1 was set in an EUV scanner, and EUV exposure was performed on a wafer on which a film to be processed and a resist film were formed on a semiconductor substrate. Then, by developing the exposed resist film, a resist pattern was formed on the semiconductor substrate on which the film to be processed was formed. This resist pattern was transferred to the film to be processed by etching, and a semiconductor device having desired characteristics could be manufactured through various processes such as formation of an insulating film and a conductive film, introduction of a dopant, and annealing.

[0166] [Example 2] Example 2 is an example in which the material of the phase shift film 4 is an RuNi film and the film thickness is adjusted to achieve a 180-degree phase difference, and the rest is the same as in Example 1.

[0167] That is, in Example 2, a phase shift film 4 made of an RuNi film was formed on the protective film 3 made of an SiO2 film by DC magnetron sputtering. The RuNi film was formed to a film thickness of 38.2 nm in an Ar gas atmosphere using an RuNi target. The content ratio (atomic ratio) of the RuNi film was Ru:Ni = 45:55. When the crystal structure of the RuNi film was measured by an X-ray diffractometer (XRD), the RuNi film had an amorphous structure.

[0168] The refractive index n and extinction coefficient (imaginary part of the refractive index) k of the RuNi film of Example 2 formed as described above at a wavelength of 13.5 nm were as follows. RuNi film: n = 0.917, k = 0.045

[0169] The relative reflectance of the phase shift film 4 made of the above RuNi film at a wavelength of 13.5 nm was 6% (the absolute reflectance was 4%). Also, the film thickness of the phase shift film 4 was 38.2 nm. This film thickness is the film thickness corresponding to a phase difference of 180 degrees when the phase shift film 4 is patterned. It was possible to make it approximately 41% thinner than the film thickness of 65 nm of the TaN film as the phase shift film 4 in Comparative Example 1 described later.

[0170] Next, in the same manner as in Example 1, a reflective mask 200 was manufactured using the above reflective mask blank 100.

[0171] In the reflective mask 200 of Example 2, since the phase shift film 4 is made of a RuNi material, the processability in a mixed gas of Cl2 gas and O2 gas is good, and the phase shift pattern 4a could be formed with high precision. Also, the film thickness of the phase shift pattern 4a was 38.2 nm, which could be made thinner than the absorber film formed of a conventional Ta-based material, and the shadowing effect could be reduced as compared with Comparative Example 1.

[0172] Also, the reflective mask 200 fabricated in Example 2 had high transfer accuracy with little LER and in-plane dimensional variation of the transferred resist pattern because the sidewall roughness of the phase shift pattern 4a was small and the cross-sectional shape was stable. In addition, as described above, since the relative reflectance of the phase shift surface was 6% (the absolute reflectance was 4%), a sufficient phase shift effect was obtained, and EUV exposure with a high exposure margin and focus margin could be performed.

[0173] Similar to the case of Example 1, a semiconductor device having desired characteristics could be manufactured using the reflective mask 200 fabricated in Example 2.

[0174] [Example 3] Example 3 is an example in which the material of the phase shift film 4 is a RuCo film and the film thickness is adjusted so as to have a phase difference of 180 degrees, and the rest is the same as in Example 1.

[0175] That is, in Example 3, a phase shift film 4 made of a RuCo film was formed on the protective film 3 made of a SiO2 film by DC magnetron sputtering. The RuCo film was formed to a film thickness of 37.9 nm in an Ar gas atmosphere using a RuCo target. The content ratio (atomic ratio) of the RuCo film was Ru:Co = 36:64. When the crystal structure of the RuCo film was measured by an X-ray diffractometer (XRD), the RuCo film had an amorphous structure.

[0176] The refractive index n and extinction coefficient (imaginary part of the refractive index) k of the RuCo film of Example 3 formed as described above at a wavelength of 13.5 nm were as follows. RuCo film: n = 0.914, k = 0.046

[0177] The relative reflectance of the phase shift film 4 made of the above RuCo film at a wavelength of 13.5 nm was 6% (absolute reflectance was 4%). Also, the film thickness of the phase shift film 4 was 37.9 nm. This film thickness is the film thickness corresponding to a phase difference of 180 degrees when the phase shift film 4 is patterned. It could be made about 42% thinner than the film thickness of 65 nm of the TaN film used as the phase shift film 4 in Comparative Example 1 described later, and the shadowing effect could be reduced.

[0178] Next, in the same manner as in Example 1, a reflective mask 200 was manufactured using the above reflective mask blank 100.

[0179] In the reflective mask 200 of Example 3, since the phase shift film 4 is made of a RuCo material, the processability in a mixed gas of Cl2 gas and O2 gas is good, and a phase shift pattern 4a could be formed with high accuracy. Also, the film thickness of the phase shift pattern 4a was 37.9 nm, which could be made thinner than the absorber film formed of a conventional Ta-based material, and the shadowing effect could be reduced compared to Comparative Example 1.

[0180] In addition, the reflective mask 200 fabricated in Example 3 had a small sidewall roughness of the phase shift pattern 4a and a stable cross-sectional shape, resulting in a high transfer accuracy with little LER and in-plane dimensional variation of the transferred resist pattern. In addition, as described above, since the relative reflectivity of the phase shift surface was 6% (absolute reflectivity was 4%), a sufficient phase shift effect was obtained, and EUV exposure with a high exposure margin and focus margin could be performed.

[0181] Similar to the case of Example 1, a semiconductor device having desired characteristics could be manufactured using the reflective mask 200 fabricated in Example 3.

[0182] [Example 4] Example 4 is an example in which the relative reflectivity of the phase shift film 4 is set to 15% (absolute reflectivity is 10%) and the film thickness is adjusted to obtain a 180-degree phase difference. Otherwise, including the material (RuCr film), it is the same as Example 1.

[0183] That is, in Example 4, a phase shift film 4 made of a RuCr film was formed on the protective film 3 made of a SiO2 film by DC magnetron sputtering. The RuCr film was formed to a film thickness of 37.9 nm in an Ar gas atmosphere using a RuCr target. The content ratio (atomic ratio) of the RuCr film was Ru:Cr = 39:61. When the crystal structure of the RuCr film was measured by an X-ray diffractometer (XRD), the RuCr film had an amorphous structure.

[0184] The refractive index n and extinction coefficient (imaginary part of the refractive index) k of the RuCr film of Example 4 formed as described above at a wavelength of 13.5 nm were as follows. RuCr film: n = 0.913, k = 0.030

[0185] The relative reflectance of the phase shift film 4 made of the above RuCr film at a wavelength of 13.5 nm was 15% (the absolute reflectance was 10%). Further, the film thickness of the phase shift film 4 was 37.9 nm. This film thickness is the film thickness corresponding to a phase difference of 180 degrees when the phase shift film 4 is patterned. It was possible to make it approximately 42% thinner than the film thickness of 65 nm of the phase shift film 4 of the TaN film in Comparative Example 1 described later.

[0186] Next, in the same manner as in Example 1, a reflective mask 200 was manufactured using the above reflective mask blank 100.

[0187] In the reflective mask 200 of Example 4, since the phase shift film 4 is made of a RuCr material, the processability with a mixed gas of Cl2 gas and O2 gas is good, and the phase shift pattern 4a can be formed with high accuracy. Further, the film thickness of the phase shift pattern 4a was 37.9 nm, which could be made thinner than the absorber film formed of a conventional Ta-based material, and the shadowing effect could be reduced more than in Example 1.

[0188] Further, the reflective mask 200 manufactured in Example 4 had a high transfer accuracy with little LER and in-plane dimensional variation of the transferred resist pattern because the sidewall roughness of the phase shift pattern 4a was small and the cross-sectional shape was stable. In addition, as described above, since the relative reflectance of the phase shift surface was 15% (the absolute reflectance was 10%), a sufficient phase shift effect was obtained, and EUV exposure with a high exposure margin and focus margin could be performed.

[0189] In the same manner as in the case of Example 1, a semiconductor device having desired characteristics could be manufactured using the reflective mask 200 manufactured in Example 4. At that time, since the reflectance of the phase shift surface was 15%, the throughput could be increased more than in Example 1.

[0190] [Example 5] Example 5 is an example in which the material of the phase shift film 4 is a RuNi film, the relative reflectance of the phase shift film 4 is set to 15% (the absolute reflectance is 10%), and the film thickness is adjusted so as to have a phase difference of 180 degrees, and the rest is the same as in Example 1.

[0191] That is, in Example 5, a phase shift film 4 made of a RuNi film was formed on the protective film 3 made of a SiO2 film by DC magnetron sputtering. The RuNi film was formed to a film thickness of 32.2 nm in an Ar gas atmosphere using a RuNi target. The content ratio (atomic ratio) of the RuNi film was Ru:Ni = 67:33. When the crystal structure of the RuNi film was measured by an X-ray diffractometer (XRD), the RuNi film had an amorphous structure.

[0192] The refractive index n and extinction coefficient (imaginary part of the refractive index) k of the RuNi film of Example 5 formed as described above at a wavelength of 13.5 nm were as follows. RuNi film: n = 0.904, k = 0.033

[0193] The relative reflectance of the phase shift film 4 made of the above RuNi film at a wavelength of 13.5 nm was 15% (the absolute reflectance was 10%). Also, the film thickness of the phase shift film 4 was 32.2 nm. This film thickness is the film thickness corresponding to a phase difference of 180 degrees when the phase shift film ④ is patterned. It was possible to make it about 50% thinner than the film thickness of 65 nm of the phase shift film 4 of the TaN film in Comparative Example 1 described later.

[0194] Next, in the same manner as in Example 1, a reflective mask 200 was manufactured using the above reflective mask blank 100.

[0195] In the reflective mask 200 of Example 5, since the phase shift film 4 is made of a RuNi material, it has good processability with a mixed gas of Cl2 gas and O2 gas, and the phase shift pattern 4a could be formed with high precision. Also, the film thickness of the phase shift pattern 4a was 32.2 nm, which could be made thinner than the absorber film formed of a conventional Ta-based material, and the shadowing effect could be reduced more than in Example 2.

[0196] Moreover, the reflective mask 200 fabricated in Example 5 had few roughnesses on the sidewalls of the phase shift pattern 4a and a stable cross-sectional shape, so it had high transfer accuracy with little LER and in-plane dimensional variations in the transferred resist pattern. In addition, as described above, since the relative reflectance of the phase shift surface was 15% (absolute reflectance was 10%), a sufficient phase shift effect was obtained, and EUV exposure with a high exposure margin and focus margin could be performed.

[0197] Similar to the case of Example 1, a semiconductor device having desired characteristics could be manufactured using the reflective mask 200 fabricated in Example 5. At that time, since the relative reflectance of the phase shift surface was 15% (absolute reflectance was 10%), the throughput could be increased more than in Example 2.

[0198] [Example 6] Example 6 is an example in which the material of the phase shift film 4 is a RuCo film, the relative reflectance of the phase shift film 4 is set to 15% (absolute reflectance is 10%), and the film thickness is adjusted so as to have a 180-degree phase difference, and other than that, it is the same as Example 1.

[0199] That is, in Example 6, a phase shift film 4 made of a RuCo film was formed on the protective film 3 made of a SiO2 film by DC magnetron sputtering. The RuCo film was formed to a film thickness of 31.9 nm in an Ar gas atmosphere using a RuCo target. The content ratio (atomic ratio) of the RuCo film was Ru:Co = 61:39. When the crystal structure of the RuCo film was measured with an X-ray diffractometer (XRD), the RuCo film had an amorphous structure.

[0200] The refractive index n and extinction coefficient (imaginary part of the refractive index) k of the RuCo film of Example 6 formed as described above at a wavelength of 13.5 nm were as follows respectively. RuCo film: n = 0.902, k = 0.034

[0201] The relative reflectance of the phase shift film 4 made of the above RuCo film at a wavelength of 13.5 nm was 15% (absolute reflectance was 10%). Also, the film thickness of the phase shift film 4 was 31.9 nm. This film thickness is the film thickness corresponding to a phase difference of 180 degrees when the phase shift film 4 is patterned. It was possible to make it about 51% thinner than the film thickness of 65 nm of the TaN film used as the phase shift film 4 in Comparative Example 1 described later.

[0202] Next, in the same manner as in Example 1, a reflective mask 200 was manufactured using the above reflective mask blank 100.

[0203] In the reflective mask 200 of Example 6, since the phase shift film 4 is made of a RuCo material, the processability with a mixed gas of Cl2 gas and O2 gas is good, and the phase shift pattern 4a can be formed with high accuracy. Also, the film thickness of the phase shift pattern 4a is 31.9 nm, which can be made thinner than the absorber film formed of a conventional Ta-based material, and the shadowing effect can be reduced more than in Example 3.

[0204] Also, the reflective mask 200 created in Example 6 had a small sidewall roughness of the phase shift pattern 4a and a stable cross-sectional shape, so it had high transfer accuracy with little LER and in-plane dimensional variation of the transferred resist pattern. In addition, as described above, since the relative reflectance of the phase shift surface is 15% (absolute reflectance is 10%), a sufficient phase shift effect was obtained, and EUV exposure with a high exposure margin and focus margin could be performed.

[0205] Similar to the case of Example 1, a semiconductor device having desired characteristics could be manufactured using the reflective mask 200 fabricated in Example 6. At this time, since the relative reflectivity of the phase shift surface was 15% (absolute reflectivity was 10%), the throughput could be increased compared to Example 3.

[0206] [Example 7] Example 7 is an example in which the relative reflectivity of the phase shift film 4 was set to 20% (absolute reflectivity was 13.3%) and the film thickness was adjusted to provide a phase difference of 180 degrees. Otherwise, including the material (RuCr film), it was the same as Example 1.

[0207] That is, in Example 7, a phase shift film 4 made of a RuCr film was formed on the protective film 3 made of a SiO2 film by DC magnetron sputtering. The RuCr film was formed to a film thickness of 32.6 nm in an Ar gas atmosphere using a RuCr target. The content ratio (atomic ratio) of the RuCr film was Ru:Cr = 56:44. When the crystal structure of the RuCr film was measured by an X-ray diffractometer (XRD), the RuCr film had an amorphous structure.

[0208] The refractive index n and extinction coefficient (imaginary part of the refractive index) k of the RuCr film of Example 7 formed as described above at a wavelength of 13.5 nm were as follows. RuCr film: n = 0.905, k = 0.026

[0209] The relative reflectivity of the phase shift film 4 made of the above RuCr film at a wavelength of 13.5 nm was 20% (absolute reflectivity was 13.3%). Also, the film thickness of the phase shift film 4 was 32.6 nm. This film thickness was the film thickness corresponding to a phase difference of 180 degrees when the phase shift film 4 was patterned. It could be made approximately 50% thinner than the film thickness of 65 nm of the TaN film used as the phase shift film 4 in Comparative Example 1 described later.

[0210] Next, similar to Example 1, a reflective mask 200 was manufactured using the above reflective mask blank 100.

[0211] In the reflective mask 200 of Example 7, since the phase shift film 4 is made of a RuCr material, it has good processability with a mixed gas of Cl2 gas and O2 gas, and the phase shift pattern 4a could be formed with high precision. Also, the film thickness of the phase shift pattern 4a was 32.6 nm, which could be made thinner than the absorber film formed of a conventional Ta-based material, and the shadowing effect could be reduced more than in Example 4.

[0212] In addition, the reflective mask 200 fabricated in Example 7 had few sidewall roughnesses of the phase shift pattern 4a and a stable cross-sectional shape, so it had high transfer accuracy with little LER and in-plane dimensional variation of the transferred resist pattern. Moreover, as described above, since the relative reflectance of the phase shift surface was 20% (absolute reflectance was 13.3%), a sufficient phase shift effect was obtained, and EUV exposure with high exposure margin and focus margin could be performed.

[0213] Similar to the case of Example 1, a semiconductor device having desired characteristics could be manufactured using the reflective mask 200 fabricated in Example 7. At that time, since the relative reflectance of the phase shift surface was 20% (absolute reflectance was 13.3%), the throughput could be increased more than in Example 4.

[0214] [Example 8] Example 8 is an example in which the material of the phase shift film 4 is an RuNi film, the relative reflectance of the phase shift film 4 is set to 20% (absolute reflectance is 13.3%), and the film thickness is adjusted so as to have a 180-degree phase difference, and otherwise it is the same as Example 1.

[0215] That is, in Example 8, a phase shift film 4 made of an RuNi film was formed on the protective film 3 made of an SiO2 film by DC magnetron sputtering. The RuNi film was formed to a film thickness of 31.8 nm in an Ar gas atmosphere using an RuNi target. The content ratio (atomic ratio) of the RuNi film was Ru:Ni = 73:27. When the crystal structure of the RuNi film was measured by an X-ray diffractometer (XRD), the RuNi film had an amorphous structure.

[0216] The refractive index n and extinction coefficient (the imaginary part of the complex refractive index) k of the RuNi film of Example 8 formed as described above at a wavelength of 13.5 nm were as follows, respectively. RuNi film: n = 0.900, k = 0.030

[0217] The relative reflectance of the phase shift film 4 made of the above RuNi film at a wavelength of 13.5 nm was 20% (the absolute reflectance was 13.3%). Also, the film thickness of the phase shift film 4 was 31.8 nm. This film thickness is the film thickness corresponding to a phase difference of 180 degrees when the phase shift film 4 is patterned. It could be made approximately 51% thinner than the film thickness of 65 nm of the TaN film as the phase shift film 4 in Comparative Example 1 described later.

[0218] Next, in the same manner as in Example 1, a reflective mask 200 was manufactured using the above reflective mask blank 100.

[0219] In the reflective mask 200 of Example 8, since the phase shift film 4 is made of RuNi material, the processability with a mixed gas of Cl2 gas and O2 gas is good, and the phase shift pattern 4a could be formed with high precision. Also, the film thickness of the phase shift pattern 4a was 31.8 nm, which could be made thinner than the absorber film formed of a conventional Ta-based material, and the shadowing effect could be reduced to the same extent as in Example 5.

[0220] Also, the reflective mask 200 fabricated in Example 8 had high transfer accuracy with little LER and in-plane dimensional variation of the transferred resist pattern because the sidewall roughness of the phase shift pattern 4a was small and the cross-sectional shape was stable. In addition, as described above, since the relative reflectance of the phase shift surface was 20% (the absolute reflectance was 13.3%), a sufficient phase shift effect was obtained, and EUV exposure with a high exposure margin and focus margin could be performed.

[0221] Similar to the case of Example 1, a semiconductor device having desired characteristics could be manufactured using the reflective mask 200 fabricated in Example 8. At that time, since the relative reflectance of the phase shift surface was 20% (the absolute reflectance was 13.3%), the throughput could be increased compared to Example 5.

[0222] [Example 9] Example 9 is an example in which the material of the phase shift film 4 is a RuCo film, the relative reflectance of the phase shift film 4 is set to 20% (the absolute reflectance is 13.3%), and the film thickness is adjusted so as to have a phase difference of 180 degrees, and the rest is the same as Example 1.

[0223] That is, in Example 9, a phase shift film 4 made of a RuCo film was formed on the protective film 3 made of a SiO2 film by DC magnetron sputtering. The RuCo film was formed to a film thickness of 31.6 nm in an Ar gas atmosphere using a RuCo target. The content ratio (atomic ratio) of the RuCo film was Ru:Co = 69:31. When the crystal structure of the RuCo film was measured by an X-ray diffractometer (XRD), the RuCo film had an amorphous structure.

[0224] The refractive index n and extinction coefficient (imaginary part of refractive index) k of the RuCo film of Example 9 formed as described above at a wavelength of 13.5 nm were as follows. RuCo film: n = 0.899, k = 0.030

[0225] The relative reflectance of the phase shift film 4 made of the above RuCo film at a wavelength of 13.5 nm was 20% (the absolute reflectance was 13.3%). Also, the film thickness of the phase shift film 4 was 31.6 nm. This film thickness is the film thickness corresponding to a phase difference of 180 degrees when the phase shift film 4 is patterned. It could be made approximately 51% thinner than the film thickness of 65 nm of the phase shift film 4 of the TaN film in Comparative Example 1 described later.

[0226] Next, in the same manner as in Example 1, a reflective mask 200 was manufactured using the above reflective mask blank 100.

[0227] In the reflective mask 200 of Example 9, since the phase shift film 4 is made of a RuCo material, it has good processability in a mixed gas of Cl2 gas and O2 gas, and the phase shift pattern 4a could be formed with high precision. Also, the film thickness of the phase shift pattern 4a was 31.6 nm, which could be made thinner than the absorber film formed of a conventional Ta-based material, and the shadowing effect could be reduced to the same extent as in Example 6.

[0228] Moreover, the reflective mask 200 fabricated in Example 9 had high transfer accuracy with little LER and in-plane dimensional variation of the transferred resist pattern because the sidewall roughness of the phase shift pattern 4a was small and the cross-sectional shape was stable. In addition, as described above, since the relative reflectance of the phase shift surface was 20% (absolute reflectance was 13.3%), a sufficient phase shift effect was obtained, and EUV exposure with a high exposure margin and focus margin could be performed.

[0229] Similar to the case of Example 1, a semiconductor device having desired characteristics could be manufactured using the reflective mask 200 fabricated in Example 9. At that time, since the relative reflectance of the phase shift surface was 20% (absolute reflectance was 13.3%), the throughput could be increased compared to Example 6.

[0230] [Example 10] Example 10 is an example in which the material of the phase shift film 4 is a RuNb film and the film thickness is adjusted to have a 180-degree phase difference, and the rest is the same as in Example 1. That is, a phase shift film 4 made of a RuNb film was formed on a substrate with a multilayer reflective film on which a protective film 3 made of a SiO2 film was formed by DC magnetron sputtering. The RuNb film was formed to a film thickness of 30.3 nm in an Ar gas atmosphere using a RuNb target. The content ratio (atomic ratio) of the RuNb film was Ru:Nb = 20:1. When the crystal structure of the RuNb film was measured by an X-ray diffractometer (XRD), the RuNb film had an amorphous structure.

[0231] The refractive index n and extinction coefficient (imaginary part of refractive index) k of the RuNb film of Example 10 formed as described above at a wavelength of 13.5 nm were as follows respectively. RuNb film: n = 0.888, k = 0.017

[0232] The relative reflectance of the phase shift film 4 made of the above RuNb film at a wavelength of 13.5 nm was 39.7% (absolute reflectance was 26.5%). Also, the film thickness of the phase shift film 4 was 30.3 nm. This film thickness is the film thickness corresponding to a phase difference of 180 degrees when the phase shift film 4 is patterned. It was possible to make it about 53% thinner than the film thickness of 65 nm of the phase shift film 4 of the TaN film in Comparative Example 1 described later.

[0233] Next, under the same conditions as in Example 1, a reflective mask 200 was manufactured using the above reflective mask blank 100. In the reflective mask 200 of Example 10, since the phase shift film 4 is made of RuNb material, it has good processability with a mixed gas of Cl2 gas and O2 gas, and the phase shift pattern 4a could be formed with high precision. Also, the film thickness of the phase shift pattern 4a was 30.3 nm, which could be made thinner than the absorber film formed of a conventional Ta-based material, and the shadowing effect could be reduced compared to Comparative Example 1.

[0234] Also, the reflective mask 200 fabricated in Example 10 had high transfer accuracy with little LER and in-plane dimensional variation of the transferred resist pattern because the sidewall roughness of the phase shift pattern 4a was small and the cross-sectional shape was stable. In addition, as described above, since the relative reflectance of the phase shift surface was 39.7% (absolute reflectance was 26.5%), a sufficient phase shift effect was obtained, and EUV exposure with a high exposure margin and focus margin could be performed.

[0235] Similar to the case of Example 1, a semiconductor device having desired characteristics could be manufactured using the reflective mask 200 fabricated in Example 10.

[0236] [Example 11] Example 11 is an example in which the material of the phase shift film 4 is a RuV film and the film thickness is adjusted to achieve a phase difference of 180 degrees, and is otherwise the same as Example 1. That is, a phase shift film 4 made of a RuV film was formed on a substrate with a multilayer reflective film on which a protective film 3 made of a SiO2 film was formed by DC magnetron sputtering. The RuV film was formed to a film thickness of 39.7 nm in an Ar gas atmosphere using a RuV target. The content ratio (atomic ratio) of the RuV film was Ru:V = 40:60. When the crystal structure of the RuV film was measured by an X-ray diffractometer (XRD), the RuV film had an amorphous structure.

[0237] The refractive index n and extinction coefficient (imaginary part of the refractive index) k of the RuV film of Example 10 formed as described above at a wavelength of 13.5 nm were as follows. RuV film: n = 0.921, k = 0.022

[0238] The relative reflectance of the phase shift film 4 made of the above RuV film at a wavelength of 13.5 nm was 18.8% (the absolute reflectance was 12.5%). Also, the film thickness of the phase shift film 4 was 39.7 nm. This film thickness is the film thickness corresponding to a phase difference of 180 degrees when the phase shift film 4 is patterned. It could be made approximately 39% thinner than the film thickness of 65 nm of the TaN film used as the phase shift film 4 in Comparative Example 1 described later.

[0239] Next, a reflective mask 200 was manufactured using the above reflective mask blank 100 under the same conditions as in Example 1. In the reflective mask 200 of Example 11, since the phase shift film 4 is a RuV material, the processability in a mixed gas of Cl2 gas and O2 gas is good, and a phase shift pattern 4a could be formed with high precision. Also, the film thickness of the phase shift pattern 4a was 39.7 nm, which could be made thinner than the absorber film formed of a conventional Ta-based material, and the shadowing effect could be reduced compared to Comparative Example 1.

[0240] In addition, the reflective mask 200 fabricated in Example 11 had high transfer accuracy with less LER and in-plane dimensional variations of the transferred resist pattern because the sidewall roughness of the phase shift pattern 4a was small and the cross-sectional shape was stable. In addition, as described above, since the relative reflectance of the phase shift surface was 18.8% (absolute reflectance was 12.5%), a sufficient phase shift effect was obtained, and EUV lithography with a high exposure margin and focus margin could be performed.

[0241] Similar to the case of Example 1, a semiconductor device having desired characteristics could be manufactured using the reflective mask 200 fabricated in Example 11.

[0242] [Example 12] Example 12 is an example in which the material of the phase shift film 4 is an RuHf film and the film thickness is adjusted to provide a 180-degree phase difference, and is otherwise the same as Example 1. That is, a phase shift film 4 made of an RuHf film was formed by DC magnetron sputtering on a substrate with a multilayer reflective film on which a protective film 3 made of an SiO2 film was formed. The RuHf film was formed to a thickness of 45.2 nm in an Ar gas atmosphere using an RuHf target. The content ratio (atomic ratio) of the RuHf film was Ru:Hf = 56:44. When the crystal structure of the RuHf film was measured with an X-ray diffractometer (XRD), the RuHf film had an amorphous structure.

[0243] The refractive index n and extinction coefficient (imaginary part of the refractive index) k of the RuHf film of Example 12 formed as described above at a wavelength of 13.5 nm were as follows. RuHf film: n = 0.928, k = 0.027

[0244] The relative reflectance of the phase shift film 4 made of the above RuHf film at a wavelength of 13.5 nm was 12.3% (the absolute reflectance was 8.2%). Further, the film thickness of the phase shift film 4 was 45.2 nm. This film thickness is the film thickness at which the phase difference corresponds to 180 degrees when the phase shift film 4 is patterned. It was possible to make it approximately 30% thinner than the film thickness of 65 nm of the phase shift film 4 of the TaN film in Comparative Example 1 described later.

[0245] Next, a reflective mask 200 was manufactured using the above reflective mask blank 100 under the same conditions as in Example 1 except that the dry etching gas was changed to Cl2 gas. In the reflective mask 200 of Example 11, since the phase shift film 4 is made of a RuHf material, Cl2 gas was used. Although the dry etching time was slightly longer than that in Example 1, the processability was good, and the phase shift pattern 4a could be formed with high accuracy. Further, the film thickness of the phase shift pattern 4a was 45.2 nm, which could be made thinner than the absorber film formed of a conventional Ta-based material, and the shadowing effect could be reduced as compared with Comparative Example 1.

[0246] Further, the reflective mask 200 manufactured in Example 12 had high transfer accuracy with less LER and in-plane dimensional variation of the transferred resist pattern because the sidewall roughness of the phase shift pattern 4a was small and the cross-sectional shape was stable. In addition, as described above, since the relative reflectance of the phase shift surface was 12.3% (the absolute reflectance was 8.2%), a sufficient phase shift effect was obtained, and EUV exposure with a high exposure margin and focus margin could be performed.

[0247] Similar to the case of Example 1, a semiconductor device having desired characteristics could be manufactured using the reflective mask 200 manufactured in Example 12.

[0248] [Example 13] Example 13 is an example in which the material of the phase shift film 4 is a RuSn film and the film thickness is adjusted to provide a phase difference of 180 degrees, and is otherwise the same as Example 1. That is, a phase shift film 4 made of a RuSn film was formed on a substrate with a multilayer reflective film on which a protective film 3 made of a SiO2 film was formed by DC magnetron sputtering. The RuSn film was formed to a film thickness of 32.2 nm in an Ar gas atmosphere using a RuSn target. The content ratio (atomic ratio) of the RuSn film was Ru:Sn = 80:20. When the crystal structure of the RuSn film was measured by an X-ray diffractometer (XRD), the RuSn film had an amorphous structure.

[0249] The refractive index n and extinction coefficient (imaginary part of the refractive index) k of the RuSn film of Example 13 formed as described above at a wavelength of 13.5 nm were as follows. RuSn film: n = 0.904, k = 0.036

[0250] The relative reflectance of the phase shift film 4 made of the above RuSn film at a wavelength of 13.5 nm was 12.8% (the absolute reflectance was 8.5%). Also, the film thickness of the phase shift film 4 was 32.2 nm. This film thickness is the film thickness corresponding to a phase difference of 180 degrees when the phase shift film 4 is patterned. It was possible to make it approximately 50% thinner than the film thickness of 65 nm of the TaN film used as the phase shift film 4 in Comparative Example 1 described later.

[0251] Next, a reflective mask 200 was manufactured using the above reflective mask blank 100 under the same conditions as in Example 1 except that the dry etching gas was changed to Cl2 gas. In the reflective mask 200 of Example 13, since the phase shift film 4 is a RuSn material, Cl2 gas was used. Although the dry etching time was slightly longer than that in Example 1, the processability was good and the phase shift pattern 4a could be formed with high accuracy. Also, the film thickness of the phase shift pattern 4a was 32.2 nm, which could be made thinner than the absorber film formed of a conventional Ta-based material, and the shadowing effect could be reduced as compared with Comparative Example 1.

[0252] In addition, the reflective mask 200 fabricated in Example 13 had a high transfer accuracy with less LER and in-plane dimensional variations of the transferred resist pattern because the sidewall roughness of the phase shift pattern 4a was small and the cross-sectional shape was stable. In addition, as described above, since the relative reflectance of the phase shift surface was 12.8% (absolute reflectance was 8.5%), a sufficient phase shift effect was obtained, and EUV lithography with a high exposure margin and focus margin could be performed.

[0253] Similar to the case of Example 1, a semiconductor device having desired characteristics could be manufactured using the reflective mask 200 fabricated in Example 13.

[0254] [Example 14] Example 14 is an example in which the material of the phase shift film 4 is a RuSi film and the film thickness is adjusted to provide a phase difference of 180 degrees, and is otherwise the same as Example 1. That is, a phase shift film 4 made of a RuSi film was formed by DC magnetron sputtering on a substrate with a multilayer reflective film on which a protective film 3 made of a SiO2 film was formed. The RuSi film was formed to a film thickness of 34.1 nm in an Ar gas atmosphere using a RuSi target. The content ratio (atomic ratio) of the RuSi film was Ru:Si = 86:14. When the crystal structure of the RuSi film was measured by an X-ray diffractometer (XRD), the RuSi film had an amorphous structure.

[0255] The refractive index n and extinction coefficient (imaginary part of the refractive index) k of the RuSi film of Example 14 formed as described above at a wavelength of 13.5 nm were as follows. RuSi film: n = 0.907, k = 0.014

[0256] The relative reflectance of the phase shift film 4 made of the above RuSi film at a wavelength of 13.5 nm was 34.1% (the absolute reflectance was 22.7%). Also, the film thickness of the phase shift film 4 was 34.1 nm. This film thickness is the film thickness corresponding to a phase difference of 180 degrees when the phase shift film 4 is patterned. It was possible to make it approximately 48% thinner than the film thickness of 65 nm of the TaN film as the phase shift film 4 in Comparative Example 1 described later.

[0257] Next, a reflective mask 200 was manufactured using the above reflective mask blank 100 under the same conditions as in Example 1 except that the dry etching gas was changed to Cl2 gas. In the reflective mask 200 of Example 14, since the phase shift film 4 is a RuSi material, Cl2 gas was used. Although the dry etching time became slightly longer compared to Example 1, the processability was good, and the phase shift pattern 4a could be formed with high accuracy. Also, the film thickness of the phase shift pattern 4a was 34.1 nm, which could be made thinner than the absorber film formed of a conventional Ta-based material, and the shadowing effect could be reduced compared to Comparative Example 1.

[0258] Also, the reflective mask 200 fabricated in Example 14 had a high transfer accuracy with less LER and in-plane dimensional variations of the transferred resist pattern because the sidewall roughness of the phase shift pattern 4a was small and the cross-sectional shape was stable. In addition, as described above, since the relative reflectance of the phase shift surface was 34.1% (the absolute reflectance was 22.7%), a sufficient phase shift effect was obtained, and EUV exposure with a high exposure margin and focus margin could be performed.

[0259] Similar to the case of Example 1, a semiconductor device having desired characteristics could be manufactured using the reflective mask 200 fabricated in Example 14.

[0260] [Example 15] Example 15 is an example in which the material of the phase shift film 4 is a RuTi film and the film thickness is adjusted to provide a phase difference of 180 degrees, and is otherwise the same as Example 1. That is, a phase shift film 4 made of a RuTi film was formed on a substrate with a multilayer reflective film on which a protective film 3 made of a SiO2 film was formed by DC magnetron sputtering. The RuTi film was formed to a film thickness of 45.7 nm in an Ar gas atmosphere using a RuTi target. The content ratio (atomic ratio) of the RuTi film was Ru:Ti = 40:60. When the crystal structure of the RuTi film was measured by an X-ray diffractometer (XRD), the RuTi film had an amorphous structure.

[0261] The refractive index n and extinction coefficient (imaginary part of the refractive index) k of the RuTi film of Example 15 formed as described above at a wavelength of 13.5 nm were as follows. RuTi film: n = 0.930, k = 0.015

[0262] The relative reflectance of the phase shift film 4 made of the above RuTi film at a wavelength of 13.5 nm was 29.0% (absolute reflectance was 19.3%). Also, the film thickness of the phase shift film 4 was 45.7 nm. This film thickness is the film thickness corresponding to a phase difference of 180 degrees when the phase shift film 4 is patterned. It was possible to make it approximately 30% thinner than the film thickness of 65 nm of the TaN film used as the phase shift film 4 in Comparative Example 1 described later.

[0263] Next, a reflective mask 200 was manufactured using the above reflective mask blank 100 under the same conditions as in Example 1 except that the dry etching gas was changed to Cl2 gas. In the reflective mask 200 of Example 15, since the phase shift film 4 is a RuTi material, Cl2 gas was used. Although the dry etching time was slightly longer than that of Example 1, the processability was good and the phase shift pattern 4a could be formed with high accuracy. Also, the film thickness of the phase shift pattern 4a was 45.7 nm, which could be made thinner than the absorber film formed of a conventional Ta-based material, and the shadowing effect could be reduced as compared with Comparative Example 1.

[0264] In addition, the reflective mask 200 fabricated in Example 15 had a high transfer accuracy with little LER and in-plane dimensional variation of the transferred resist pattern because the sidewall roughness of the phase shift pattern 4a was small and the cross-sectional shape was stable. Moreover, as described above, since the relative reflectivity of the phase shift surface was 29.0% (absolute reflectivity: 19.3%), a sufficient phase shift effect was obtained, and EUV lithography with a large exposure margin and focus margin could be performed.

[0265] Similar to the case of Example 1, a semiconductor device having desired characteristics could be manufactured using the reflective mask 200 fabricated in Example 15.

[0266] [Example 16] Example 16 is an example in which the material of the phase shift film 4 is an RuV film and the film thickness is adjusted to provide a 180-degree phase difference. The reflective mask blank 100 of Example 16 is the same as that of Example 1, except that the protective film 3 is a CrOC film and a phase shift film 4 made of an RuV film is formed.

[0267] That is, in Example 16, similar to Example 1, a backside conductive film 5 made of a CrN film was formed on the second main surface (back surface) of the SiO2-TiO2-based glass substrate 1, a multilayer reflective film 2 was formed on the main surface (first main surface) of the opposite substrate 1, and a protective film 3 made of a CrOC film was formed by DC magnetron sputtering. The CrOC film was formed to a thickness of 2.5 nm by reactive sputtering in a mixed gas atmosphere of Ar gas, CO2 gas, and He gas using a Cr target. The content ratio (atomic ratio) of the CrOC film was Cr:O:C = 71:15:14.

[0268] Next, a phase shift film 4 made of a RuV film was formed on the protective film 3 by DC magnetron sputtering. The RuV film was formed to a film thickness of 33.0 nm in an Ar gas atmosphere using a RuV target. The content ratio (atomic ratio) of the RuV film was Ru:V = 60:40. When the crystal structure of the RuV film was measured by an X-ray diffractometer (XRD), the RuV film had an amorphous structure.

[0269] The refractive index n and extinction coefficient (imaginary part of refractive index) k of the RuV film of Example 16 formed as described above at a wavelength of 13.5 nm were as follows. RuV film: n = 0.906, k = 0.024

[0270] The relative reflectance of the phase shift film 4 made of the above RuV film at a wavelength of 13.5 nm was 21.1% (absolute reflectance was 14.1%). Also, the film thickness of the phase shift film 4 was 33.0 nm. This film thickness is the film thickness corresponding to a phase difference of 180 degrees when the phase shift film 4 is patterned. It was possible to make it approximately 49% thinner than the film thickness of 65 nm of the phase shift film 4 of the TaN film in Comparative Example 1 described later.

[0271] Next, a reflective mask 200 was manufactured using the above reflective mask blank 100.

[0272] First, a resist film 11 was formed to a thickness of 100 nm on the phase shift film 4 of the reflective mask blank 100. Then, a desired pattern was drawn (exposed) on this resist film 11, and further developed and rinsed to form a predetermined resist pattern 11a. Next, using the resist pattern 11a as a mask, dry etching of the RuV film (phase shift film 4) was performed using a mixed gas of CF4 gas and O2 gas (gas flow rate ratio CF4:O2 = 1:1) to form a phase shift pattern 4a.

[0273] Thereafter, the resist pattern was removed using ashing or a resist stripper. Finally, wet cleaning using pure water (DIW) was performed to fabricate the reflective mask 200. Note that mask defect inspection can be performed after wet cleaning as necessary, and mask defect correction can be appropriately performed.

[0274] In the reflective mask 200 of Example 16, since the phase shift film is a RuV material, it has good processability with fluorine-based gases and can form a phase shift pattern with high precision. Also, the film thickness of the phase shift pattern was 33.0 nm, which could be made thinner than the absorber film formed of a conventional Ta-based material.

[0275] Also, the reflective mask 200 fabricated in Example 16 had high transfer accuracy with little LER and in-plane dimensional variation of the transferred resist pattern because the sidewall roughness of the phase shift pattern 4a was small and the cross-sectional shape was stable. In addition, as described above, since the relative reflectance of the phase shift surface (reflectance with respect to the reflectance of the multilayer reflective film with a protective film) was 21.1% (absolute reflectance was 14.1%), a sufficient phase shift effect was obtained, and EUV exposure with a high exposure margin and focus margin could be performed.

[0276] The reflective mask 200 fabricated in Example 16 was set in an EUV scanner, and EUV exposure was performed on a wafer on which a film to be processed and a resist film were formed on a semiconductor substrate. Then, by developing this exposed resist film, a resist pattern was formed on the semiconductor substrate on which the film to be processed was formed. This resist pattern was transferred to the film to be processed by etching, and a semiconductor device having desired characteristics could be manufactured through various processes such as formation of an insulating film and a conductive film, introduction of a dopant, and annealing.

[0277] [Example 17] Example 17 is an example in which the relative reflectance of the phase shift film 4 is set to 27% (absolute reflectance is 18%) and the film thickness is adjusted to have a phase difference of 220 degrees, and other than that, including the material (RuCr film), it is the same as Example 1.

[0278] That is, in Example 17, a phase shift film 4 made of a RuCr film was formed on a substrate with a multilayer reflective film on which a protective film 3 made of a SiO2 film was formed by DC magnetron sputtering. The RuCr film was formed to a film thickness of 38.6 nm in an Ar gas atmosphere using a RuCr target. The content ratio (atomic ratio) of the RuCr film was Ru:Cr = 85:15. When the crystal structure of the RuCr film was measured by an X-ray diffractometer (XRD), the RuCr film had an amorphous structure.

[0279] The refractive index n and extinction coefficient (imaginary part of the refractive index) k of the RuCr film of Example 17 formed as described above at a wavelength of 13.5 nm were as follows. RuCr film: n = 0.895, k = 0.020

[0280] The relative reflectance of the phase shift film 4 made of the above RuCr film at a wavelength of 13.5 nm was 27% (absolute reflectance was 18%). Also, the film thickness of the phase shift film 4 was 38.6 nm. This film thickness is the film thickness corresponding to a phase difference of 220 degrees when the phase shift film 4 is patterned. It could be made approximately 41% thinner than the film thickness of 65 nm of the TaN film used as the phase shift film 4 in Comparative Example 1 described later.

[0281] Next, a reflective mask 200 was fabricated using the above reflective mask blank 100 under the same conditions as in Example 1. Also, the film thickness of the phase shift pattern 4a was 38.6 nm, which could be made thinner than the absorber film formed of a conventional Ta-based material, and the shadowing effect could be reduced compared to Comparative Example 1. Also, compared with a reflective mask fabricated by adjusting with the same material as in Example 17 so that the relative reflectance is 27% (absolute reflectance is 18%) and the phase difference is 180 degrees, the contrast was improved by 1.3 times.

[0282] Similar to the case of Example 1, a semiconductor device having desired characteristics could be manufactured using the reflective mask 200 fabricated in Example 17.

[0283] [Example 18] Example 18 is an example in which the relative reflectance of the phase shift film 4 is set to 20% (absolute reflectance is 13.3%) and the film thickness is adjusted so as to obtain a phase difference of 140 degrees. Otherwise, including the material (RuCr film), it is the same as Example 1.

[0284] That is, in Example 18, on a substrate with a multilayer reflective film on which a protective film 3 made of SiO2 film was formed, a phase shift film 4 made of RuCr film was formed by DC magnetron sputtering method. The RuCr film was formed to a film thickness of 30.4 nm in an Ar gas atmosphere using a RuCr target. The content ratio (atomic ratio) of the RuCr film was Ru:Cr = 66:34. When the crystal structure of the RuCr film was measured by an X-ray diffractometer (XRD), the RuCr film had an amorphous structure.

[0285] The refractive index n and extinction coefficient (imaginary part of refractive index) k of the RuCr film of Example 18 formed as described above at a wavelength of 13.5 nm were as follows. RuCr film: n = 0.916, k = 0.031

[0286] The relative reflectance of the phase shift film 4 made of the above RuCr film at a wavelength of 13.5 nm was 20% (absolute reflectance was 13.3%). Also, the film thickness of the phase shift film 4 was 30.4 nm. This film thickness is the film thickness corresponding to a phase difference of 140 degrees when the phase shift film 4 is patterned. It could be made approximately 53% thinner than the film thickness of 65 nm of the phase shift film 4 of the TaN film in Comparative Example 1 described later.

[0287] Next, under the same conditions as in Example 1, a reflective mask 200 was fabricated using the above reflective mask blank 100. Also, the film thickness of the phase shift pattern 4a was 30.4 nm, which could be made thinner than the absorber film formed of a conventional Ta-based material, and the shadowing effect could be reduced as compared with Comparative Example 1. Further, compared with a reflective mask fabricated by adjusting to have a relative reflectance of 20% (absolute reflectance: 13.3%) and a phase difference of 180 degrees using the same materials as in Example 18, the contrast was improved by 1.5 times.

[0288] Similar to the case of Example 1, a semiconductor device having desired characteristics could be manufactured using the reflective mask 200 fabricated in Example 18.

[0289] [Example 19] Example 19 is an example in which the film thickness of the protective film was changed, the material of the phase shift film 4 was a RuCrN film, and the film thickness was adjusted to have a phase difference of 180 degrees, and other than that, it was the same as in Example 1.

[0290] That is, in Example 18, on a substrate with a multilayer reflective film on which a protective film 3 made of a SiO2 film with a film thickness of 3.2 nm was formed, a phase shift film 4 made of a RuCrN film was formed by DC magnetron sputtering. The RuCrN film was formed to have a film thickness of 34.6 nm in an atmosphere of Ar gas and N2 gas using a Ru target and a Cr target. The content ratio (atomic ratio) of the RuCrN film was Ru:Cr:N = 55:38:7. When the crystal structure of the RuCrN film was measured by an X-ray diffractometer (XRD), the RuCrN film had an amorphous structure.

[0291] The refractive index n and extinction coefficient (imaginary part of the refractive index) k of the RuCrN film of Example 19 formed as described above at a wavelength of 13.5 nm were as follows. RuCr film: n = 0.905, k = 0.025

[0292] The relative reflectance of the phase shift film 4 made of the above RuCrN film at a wavelength of 13.5 nm was 16% (the absolute reflectance was 10.7%). Also, the film thickness of the phase shift film 4 was 34.6 nm. This film thickness is the film thickness corresponding to a phase difference of 180 degrees when the phase shift film 4 is patterned. It was possible to make it about 47% thinner than the film thickness of 65 nm of the TaN film as the phase shift film 4 in Comparative Example 1 described later.

[0293] Next, under the same conditions as in Example 1, a reflective mask 200 was fabricated using the above reflective mask blank 100. Also, the film thickness of the phase shift pattern 4a was 34.6 nm, which could be made thinner than the absorber film formed of a conventional Ta-based material, and the shadowing effect could be reduced as compared with Comparative Example 1.

[0294] Similar to the case of Example 1, a semiconductor device having desired characteristics could be manufactured using the reflective mask 200 fabricated in Example 19.

[0295] [Comparative Example 1] In Comparative Example 1, an Ru film was used as the protective film 3, and a single-layer TaN film was used as the phase shift film 4. The reflective mask blank 100 and the reflective mask 200 were manufactured by the same structure and method as in Example 1, and a semiconductor device was manufactured by the same method as in Example 1.

[0296] The Ru film (protective film 3) was formed on the multilayer reflective film 2 of the mask blank structure of Example 1. This Ru film was formed to a film thickness of 2.5 nm by an ion beam sputtering method in an Ar gas atmosphere using Ru as a target. The single-layer TaN film was formed on the Ru film. The TaN film was formed by performing reactive sputtering in a mixed gas atmosphere of Xe gas and N2 gas using Ta as a target. The film thickness of the TaN film was 65 nm, and the elemental ratio of this film was 88 atomic% Ta and 12 atomic% N.

[0297] The refractive index n and the extinction coefficient (the imaginary part of the refractive index) k of the TaN film formed as described above at a wavelength of 13.5 nm were as follows, respectively. TaN film: n = 0.949, k = 0.032

[0298] The phase difference of the phase shift film 4 made of the above single-layer TaN film at a wavelength of 13.5 nm is 180 degrees. The relative reflectance with respect to the two surfaces of the multilayer reflective film 2 was 1.7%. Also, the absolute reflectance of the phase shift film 4 was 1.1%.

[0299] Thereafter, in the same manner as in Example 1, a resist film 11 was formed on the phase shift film 4 made of a single-layer TaN film, and desired pattern drawing (exposure), development, and rinsing were performed to form a resist pattern 11a. Then, using this resist pattern 11a as a mask, the phase shift film 4 made of a TaN single-layer film was dry-etched using chlorine gas to form a phase shift pattern 4a. Removal of the resist pattern 11a and mask cleaning were also performed in the same manner as in Example 1 to manufacture a reflective mask 200.

[0300] The film thickness of the phase shift pattern 4a was 65 nm, and the shadowing effect could not be reduced. In addition, as described above, since the relative reflectance of the phase shift surface was 1.7% (absolute reflectance was 1.1%), a sufficient phase shift effect could not be obtained, and EUV exposure with a high exposure margin and focus margin could not be performed.

[0301] As described above, the total film thickness of the phase shift films 4 of Examples 1 to 19 could be made about 30% thinner than the film thickness of 65 nm of the phase shift film 4 of Comparative Example 1. Therefore, it became clear that the shadowing effect could be reduced in the reflective masks 200 of Examples 1 to 19.

Explanation of Reference Numerals

[0302] 1 Substrate 2 Multilayer reflective film 3 Protective film 4 Phase shift film 4a Phase shift pattern 5 Backside conductive film 11 Resist film 11a Resist pattern 100 Reflective mask blank 200 Reflective mask

Claims

1. A reflective mask blank having, in this order, a multilayer reflective film and a phase shift film for shifting the phase of EUV light on a substrate, wherein the phase shift film has a thin film made of a material containing a metal containing ruthenium (Ru) and at least one element selected from chromium (Cr), nickel (Ni), cobalt (Co), aluminum (Al), silicon (Si), titanium (Ti), vanadium (V), germanium (Ge), niobium (Nb), molybdenum (Mo), tin (Sn), tellurium (Te), hafnium (Hf), tungsten (W), and rhenium (Re). The reflective mask blank is characterized by this.

2. The reflective mask blank according to claim 1, wherein the crystal structure of the phase shift film is amorphous.

3. The reflective mask blank according to claim 1 or 2, wherein the phase shift film is a thin film made of a material containing a metal containing ruthenium (Ru) and at least one element selected from chromium (Cr), nickel (Ni), and cobalt (Co).

4. The reflective mask blank according to claim 3, wherein the composition ratio (Ru:Cr) of the Ru and the Cr is 15:1 to 1:

20.

5. The reflective mask blank according to claim 3, wherein the composition ratio (Ru:Ni) of the Ru and the Ni is 20:1 to 1:

4.

6. The reflective mask blank according to claim 3, wherein the composition ratio (Ru:Co) of the Ru and the Co is 20:1 to 1:

5.

7. The reflective mask blank further has a protective film between the multilayer reflective film and the phase shift film, wherein the protective film is made of a material containing silicon (Si) and oxygen (O). The reflective mask blank according to any one of claims 1 to 6 is characterized by this.

8. A reflective mask having a phase shift pattern in which the phase shift film in the reflective mask blank according to any one of claims 1 to 7 is patterned.

9. A method for manufacturing a reflective mask, characterized by patterning the phase shift film in the reflective mask blank according to any one of claims 1 to 7 with a dry etching gas containing a chlorine-based gas and an oxygen gas to form a phase shift pattern.

10. A method for manufacturing a semiconductor device, comprising the step of setting the reflective mask according to claim 8 in an exposure apparatus having an exposure light source that emits EUV light, and transferring a transfer pattern onto a resist film formed on a substrate to be transferred.

Images