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

Abstract

To provide a substrate with a multilayer reflection film, a reflective mask blank, a method for manufacturing a reflective mask, and a method for manufacturing a semiconductor device, capable of preventing film peeling of the multilayer reflection film due to cleaning or the like in a mask manufacturing process and during use of the mask, and capable of reducing occurrence of defects on an absorber film caused by the film peeling of the multilayer reflection film.SOLUTION: The substrate with a multilayer reflective film 10 includes a substrate 10 and a multilayer reflective film 12 formed on a main surface of the substrate 10. The multilayer reflective film 12 has a structure in which a high refractive index layer and a low refractive index layer are alternately laminated. The high refractive index layer is made of a material containing Si. The low refractive index layer is made of a material containing a transition metal. The outermost peripheral portion 60 of the multilayer reflective film 12 is made of a compound containing Si and a transition metal. The ratio of the content (atomic%) of Si to the total content (atomic%) of Si and the transition metal in the compound is 0.50 or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] In recent years, with the increasing demand for higher density and precision in VLSI devices, EUV lithography, an exposure technology using extreme ultraviolet (EUV) light, is seen as a promising option. EUV light refers to light in the wavelength range of soft X-rays or vacuum ultraviolet light, specifically light with a wavelength of approximately 0.2 to 100 nm.

[0003] A reflective mask has a multilayer reflective film formed on a substrate to reflect exposure light, and an absorber pattern, which is a patterned absorber film formed on the multilayer reflective film to absorb the exposure light. Light incident on the reflective mask mounted on an exposure machine for transferring a pattern onto a semiconductor substrate is absorbed in the areas with the absorber pattern and reflected by the multilayer reflective film in areas without the absorber pattern. The light image reflected by the multilayer reflective film is transferred onto a semiconductor substrate such as a silicon wafer through a reflection optical system.

[0004] Generally, a multilayer reflective film is used in which elements with different refractive indices are periodically stacked. For example, a Mo / Si periodic stacked film in which Mo films and Si films are alternately stacked for about 40 periods is preferably used as a multilayer reflective film for EUV light with a wavelength of 13 to 14 nm.

[0005] Patent Document 1 describes a reflective mask blank for EUV lithography that includes a substrate, a multilayer reflective film formed on the surface of the substrate, a protective film formed on the multilayer reflective film, and an absorbing film formed on the protective film. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2016-122751 DISCLOSURE OF THE INVENTION

[0007] A reflective mask blank generally has a structure in which a multilayer reflective film that reflects exposure light (EUV light) is formed on one main surface of a substrate, and an absorber film that absorbs exposure light (EUV light) is formed on this multilayer reflective film.

[0008] When manufacturing a reflective mask using a reflective mask blank, first a resist film for electron beam lithography is formed on the surface of the reflective mask blank. Next, a desired pattern is written on this resist film with an electron beam and the pattern is developed to form a resist pattern. Next, using this resist pattern as a mask, the absorber film is dry-etched to form an absorber pattern (transfer pattern). In this way, a reflective mask can be manufactured in which an absorber pattern is formed on the multilayer reflective film.

[0009] In recent years, the demand for quality in reflective masks has increased, and defects caused by the multilayer reflective film in multilayer reflective film coated substrates and reflective mask blanks, which were not a problem in the past, have become a problem.

[0010] The multilayer reflective film in a reflective mask blank is usually formed on the main surface of the substrate using an ion beam sputtering device or a magnetron sputtering device. The multilayer reflective film may be formed so as to wrap around the edge surface of the substrate. Alternatively, the multilayer reflective film may be formed so as not to wrap around the edge surface of the substrate. When the substrate is held using an electrostatic chuck device during formation of the multilayer reflective film, the multilayer reflective film is usually formed so as to wrap around the edge surface of the substrate. On the other hand, when the substrate is held using a mechanical chuck device (e.g., the chuck device described in JP 2005-77845 A) during formation of the multilayer reflective film, the peripheral portion of the main surface of the substrate is covered by the upper plate of the chuck device. Therefore, the multilayer reflective film is usually formed so as not to wrap around the edge surface of the substrate. The resist film is then formed on the entire surface of the reflective mask blank. In order to prevent dust generation due to peeling of the resist film from the peripheral edge of the substrate, the resist film is usually removed from the peripheral edge of the substrate where the mask pattern is not formed (edge ​​rinse).

[0011] When a reflective mask is manufactured as described above using a reflective mask blank in which the resist film has been removed from the peripheral edge of the substrate (in other words, no resist film is formed on the peripheral edge of the substrate), no resist film is formed on the peripheral edge of the substrate. Therefore, the exposed absorber film is removed by etching, exposing the multilayer reflective film underneath the absorber film. Typically, in the manufacturing process of a reflective mask, after forming the absorber pattern, wet cleaning is performed using an acidic or alkaline aqueous solution (chemical solution) to remove the resist pattern. Also, in the manufacturing of semiconductor devices, wet cleaning using chemical solutions is performed to remove foreign matter that has adhered to the reflective mask during exposure. These cleaning processes are performed at least multiple times. A Mo / Si periodic stacked film, in which Mo and Si films are alternately stacked in approximately 40 cycles, is preferably used as a multilayer reflective film for EUV light with a wavelength of 13 to 14 nm. This cleaning can damage the exposed multilayer reflective film on the peripheral edge of the substrate, causing film peeling. Such film peeling of the multilayer reflective film may cause serious pattern defects.

[0012] In the multilayer reflective film-coated substrate and reflective mask blank described in Patent Document 1, a modified region is formed in the peripheral region of the multilayer reflective film. This modified region is formed from a compound of the material of the high refractive index layer and the material of the low refractive index layer that constitute the multilayer reflective film. By forming such a modified region, it is possible to reduce the occurrence of defects caused by film peeling of the multilayer reflective film or the absorber film. A material containing silicon (Si) is used as the material for the high refractive index layer. A material containing molybdenum (Mo) is used as the material for the low refractive index layer.

[0013] According to the multilayer reflective film coated substrate and reflective mask blank described in Patent Document 1, a modified region is formed in the outer peripheral region of the multilayer reflective film, thereby improving the chemical resistance of the outer peripheral edge of the multilayer reflective film and reducing peeling of the multilayer reflective film. However, since the modified region contains Si, and a silicide film with a high Si content has high compressive stress, there has been a problem in that peeling of the multilayer reflective film and defects on the absorber film caused by peeling cannot be sufficiently reduced.

[0014] The present invention has been made to solve the above-mentioned problems, and aims to provide a multilayer reflective film-coated substrate, a reflective mask blank, a method for manufacturing a reflective mask, and a method for manufacturing a semiconductor device, which are capable of preventing peeling of the multilayer reflective film due to cleaning or the like during the mask manufacturing process and when the mask is used, and reducing the occurrence of defects on the multilayer reflective film or absorber film caused by peeling of the multilayer reflective film.

[0015] In order to solve the above problems, the present invention has the following configuration.

[0016] (Configuration 1) A multilayer reflective film coated substrate including a substrate and a multilayer reflective film formed on a main surface of the substrate, the multilayer reflective film has a structure in which high refractive index layers and low refractive index layers are alternately stacked, the high-refractive-index layer is made of a material containing Si, and the low-refractive-index layer is made of a material containing a transition metal, the outermost periphery of the multilayer reflective film is made of a compound containing Si and a transition metal, The multilayer reflective film-coated substrate is characterized in that the ratio of the content (atomic %) of Si to the total content (atomic %) of Si and the transition metal in the compound is 0.50 or less.

[0017] (Configuration 2) 2. The multilayer reflective film coated substrate according to configuration 1, wherein the compound contains oxygen.

[0018] (Configuration 3) 3. The multilayer reflective film coated substrate according to configuration 2, wherein the content of oxygen in the compound is 0.5 atomic % or more and 75 atomic % or less.

[0019] (Configuration 4) 4. The multilayer reflective film coated substrate according to any one of configurations 1 to 3, wherein a protective film is formed on the multilayer reflective film.

[0020] (Configuration 5) A reflective mask blank having a multilayer reflective film formed on a main surface of a substrate, the multilayer reflective film being formed by alternately stacking high refractive index layers and low refractive index layers, and an absorber film, the high-refractive-index layer in the multilayer reflective film is made of a material containing Si, and the low-refractive-index layer is made of a material containing a transition metal, an outermost portion of the multilayer reflective film formed on the main surface is made of a compound containing Si and a transition metal; A reflective mask blank characterized in that the ratio of the content (atomic %) of Si to the total content (atomic %) of Si and the transition metal in the compound is 0.50 or less.

[0021] (Configuration 6) 6. The reflective mask blank according to claim 5, wherein the compound contains oxygen.

[0022] (Configuration 7) 7. The reflective mask blank according to structure 6, wherein the oxygen content in the compound is 0.5 atomic % or more and 75 atomic % or less.

[0023] (Configuration 8) 8. The reflective mask blank according to any one of structures 5 to 7, wherein a protective film made of a material having an etching selectivity different from that of the absorber film is formed between the multilayer reflective film and the absorber film.

[0024] (Configuration 9) 9. The reflective mask blank according to any one of structures 5 to 8, wherein a resist film is formed on the absorber film.

[0025] (Configuration 10) 10. The reflective mask blank according to configuration 9, wherein the outer edge of the resist film is located above the outermost periphery of the multilayer reflective film made of the compound.

[0026] (Configuration 11) A method for producing a reflective mask, comprising preparing a reflective mask blank according to Configuration 9 or 10, and patterning the absorber film to form an absorber pattern on the multilayer reflective film.

[0027] (Configuration 12) 12. A method for manufacturing a semiconductor device, comprising the step of transferring an absorber pattern onto a resist film on a semiconductor substrate using a reflective mask obtained by the method for manufacturing a reflective mask according to claim 11.

[0028] According to the present invention, it is possible to provide a substrate with a multilayer reflective film, a reflective mask blank, a method for manufacturing a reflective mask, and a method for manufacturing a semiconductor device, which are capable of preventing peeling of the multilayer reflective film due to cleaning during the mask manufacturing process and when using the mask, and reducing the occurrence of defects on the multilayer reflective film or on the absorber film caused by peeling of the multilayer reflective film. [Brief explanation of the drawings]

[0029] [Figure 1] 1 is a cross-sectional view schematically illustrating an example of a multilayer reflective film-coated substrate according to the present embodiment. [Figure 2]FIG. 1 is a cross-sectional view schematically illustrating an example of a reflective mask blank according to an embodiment of the present invention. [Figure 3] FIG. 2 is a cross-sectional view schematically illustrating another example of a reflective mask blank according to the present embodiment. [Figure 4a-f] 1A to 1C are schematic diagrams showing an example of a method for manufacturing a reflective mask. [Figure 5] FIG. 1 is a schematic diagram showing a pattern transfer device. [Figure 6] FIG. 2 is an enlarged schematic cross-sectional view of the outermost periphery of the multilayer reflective film. [Figure 7] FIG. 1 is a schematic diagram showing an example of an ion beam sputtering apparatus used to form a multilayer reflective film. [Figure 8] FIG. 1 is a schematic diagram showing an example of an ion beam sputtering apparatus used to form a multilayer reflective film. DETAILED DESCRIPTION OF THE INVENTION

[0030] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that the following embodiments are intended to specifically explain the present invention, and are not intended to limit the scope of the present invention.

[0031] Fig. 1 is a cross-sectional view schematically illustrating an example of a multilayer reflective film-coated substrate 100 according to this embodiment. The multilayer reflective film-coated substrate 100 illustrated in Fig. 1 includes a substrate 10 and a multilayer reflective film 12 formed on the substrate 10. A protective film 14 may be formed on the multilayer reflective film 12. A back surface conductive film 22 for electrostatic chuck use may be formed on the back surface of the substrate 10 (the surface opposite to the side on which the multilayer reflective film 12 is formed).

[0032] In this specification, "on" a substrate or a film includes not only cases where it is in contact with the upper surface of the substrate or film, but also cases where it is not in contact with the upper surface of the substrate or film. In other words, "on" a substrate or a film includes cases where a new film is formed above the substrate or film, or cases where another film is interposed between the substrate or film. Furthermore, "on" does not necessarily mean the upper side in the vertical direction. "On" merely indicates the relative positional relationship of the substrate, film, etc.

[0033] <Substrate> To prevent distortion of the transferred pattern due to heat during exposure to EUV light, the substrate 10 preferably has a low thermal expansion coefficient within the range of 0±5 ppb / ° C. Materials having a low thermal expansion coefficient within this range include, for example, SiO2-TiO2-based glass and multi-component glass ceramics.

[0034] The main surface of the substrate 10 on which a transfer pattern (an absorber pattern, described later) is formed is preferably processed to improve its flatness. By improving the flatness of the main surface of the substrate 10, the positional accuracy and transfer accuracy of the pattern can be improved. For example, in the case of EUV exposure, the flatness in a 132 mm × 132 mm area of ​​the main surface of the substrate 10 on which the transfer pattern is formed is preferably 0.1 μm or less, more preferably 0.05 μm or less, and particularly preferably 0.03 μm or less. Furthermore, the main surface opposite the side on which the transfer pattern is formed (the back surface) is the surface fixed to the exposure apparatus by an electrostatic chuck. In a 142 mm × 142 mm area of ​​the back surface, the flatness is 0.1 μm or less, more preferably 0.05 μm or less, and particularly preferably 0.03 μm or less. Note that, in this specification, flatness is a value representing the warpage (deformation) of the surface, as indicated by TIR (Total Indicated Reading). Specifically, the flatness is the absolute value of the difference in height between the highest point on the substrate surface above the focal plane, which is determined by the least squares method using the substrate surface as a reference, and the lowest point on the substrate surface below this focal plane.

[0035] In the case of EUV exposure, the surface roughness of the main surface of the substrate 10 on which the transfer pattern is formed is preferably 0.1 nm or less in terms of root mean square roughness (Rq). The surface roughness can be measured using an atomic force microscope.

[0036] The substrate 10 preferably has high rigidity to prevent deformation due to film stress of the films (such as the multilayer reflective film 12) formed thereon, and particularly preferably has a high Young's modulus of 65 GPa or more.

[0037] <Multilayer reflective film> The multilayer reflective film 12 has a structure in which a plurality of layers whose main components are elements with different refractive indices are periodically laminated. Generally, the multilayer reflective film 12 is made of a multilayer film in which thin films (high refractive index layers) of light elements or their compounds, which are high refractive index materials, and thin films (low refractive index layers) of heavy elements or their compounds, which are low refractive index materials, are alternately laminated for about 40 to 60 periods. To form the multilayer reflective film 12, high refractive index layers and low refractive index layers may be laminated in this order multiple times from the substrate 10 side. In this case, one laminate structure (high refractive index layer / low refractive index layer) constitutes one period.

[0038] It is preferable that the top layer of the multilayer reflective film 12, i.e., the surface layer of the multilayer reflective film 12 opposite the substrate 10, be a high refractive index layer. When a high refractive index layer and a low refractive index layer are stacked in this order from the substrate 10 side, the top layer will be a low refractive index layer. However, if a low refractive index layer is the surface of the multilayer reflective film 12, the low refractive index layer will be easily oxidized, reducing the reflectance of the surface of the multilayer reflective film. Therefore, it is preferable to form a high refractive index layer on the low refractive index layer. On the other hand, when a low refractive index layer and a high refractive index layer are stacked in this order from the substrate 10 side, the top layer will be a high refractive index layer. In that case, the top high refractive index layer will be the surface of the multilayer reflective film 12.

[0039] The high refractive index layer included in the multilayer reflective film 12 is a layer made of a material containing Si. The high refractive index layer may contain elemental Si or a Si compound. The Si compound may contain Si and at least one element selected from the group consisting of B, C, N, O, and H. By using a layer containing Si as the high refractive index layer, a multilayer reflective film with excellent reflectance for EUV light can be obtained.

[0040] The low refractive index layer included in the multilayer reflective film 12 is a layer made of a material containing a transition metal. The transition metal included in the low refractive index layer is preferably at least one transition metal selected from the group consisting of Mo, Ru, Rh, and Pt. The low refractive index layer is more preferably a layer made of a material containing Mo.

[0041] For example, as the multilayer reflective film 12 for EUV light with a wavelength of 13 to 14 nm, a Mo / Si multilayer film in which Mo films and Si films are alternately stacked in about 40 to 60 periods can be preferably used.

[0042] The reflectance of such a single multilayer reflective film 12 is, for example, 65% or more. The upper limit of the reflectance of the multilayer reflective film 12 is, for example, 73%. The thickness and period of the layers included in the multilayer reflective film 12 can be selected so as to satisfy Bragg's law.

[0043] The multilayer reflective film 12 can be formed by a known method, for example, ion beam sputtering.

[0044] For example, when the multilayer reflective film 12 is a Mo / Si multilayer film, a Mo film having a thickness of about 3 nm is formed on the substrate 10 by ion beam sputtering using a Mo target. Next, a Si film having a thickness of about 4 nm is formed using a Si target. By repeating this process, the multilayer reflective film 12 can be formed in which 40 to 60 periods of Mo / Si films are stacked. In this case, the surface layer of the multilayer reflective film 12 on the side opposite to the substrate 10 is a layer containing Si (Si film). The thickness of one period of the Mo / Si film is 7 nm.

[0045] In the multilayer reflective film-coated substrate 100 of this embodiment, the outermost periphery of the multilayer reflective film 12 contains a compound containing Si contained in the high-refractive-index layer and a transition metal contained in the low-refractive-index layer. In such a compound, the ratio of the Si content (atomic %) to the total content (atomic %) of Si and the transition metal is 0.50 or less, preferably 0.45 or less, and more preferably 0.40 or less. Furthermore, the ratio of the Si content (atomic %) to the total content (atomic %) of Si and the transition metal is preferably 0.10 or more. By adjusting the proportions of Si and the transition metal contained in the compound within this range, compressive stress in the compound is reduced, thereby preventing peeling of the multilayer reflective film during mask manufacturing processes and cleaning during mask use. As a result, the occurrence of defects on the multilayer reflective film or absorber film due to peeling of the multilayer reflective film can be reduced. Note that the above conditions do not need to be satisfied throughout the entire compound; cases in which the above conditions are satisfied in at least a portion of the compound are also within the scope of the present invention.

[0046] The compound contained in the outermost peripheral portion of the multilayer reflective film 12 preferably further contains oxygen. When the compound contains oxygen, the chemical resistance of the outermost peripheral portion of the multilayer reflective film 12 is improved. In addition, the reflectance of the outermost peripheral portion of the multilayer reflective film 12, which does not contribute to pattern transfer, to exposure light (EUV light) can be reduced, which further improves the pattern transfer accuracy during exposure.

[0047] The oxygen content in the compound contained in the outermost peripheral portion of the multilayer reflective coating 12 is preferably 0.5 atomic % or more and 75 atomic % or less, more preferably 5 atomic % or more and 60 atomic % or less, and even more preferably 5 atomic % or more and 40 atomic % or less. By adjusting the oxygen content in the compound within this range, the chemical resistance of the outermost peripheral portion of the multilayer reflective coating 12 is further improved. The compound contained in the outermost peripheral portion of the multilayer reflective coating 12 can be made to contain oxygen by temporarily removing the multilayer reflective coating-coated substrate from the chamber to the atmosphere after the multilayer reflective coating 12 is formed, and then forming the protective film 14 discontinuously with the formation of the multilayer reflective coating 12. The oxygen content in the compound can also be adjusted by adjusting the conditions for cleaning and heat treatment of the multilayer reflective coating-coated substrate.

[0048] When the transition metal contained in the low-refractive-index layer is molybdenum (Mo) and the material contained in the high-refractive-index layer is silicon (Si), the outermost periphery of the multilayer reflective film 12 is formed of metal silicide (specifically, molybdenum silicide). Molybdenum is eluted by sulfuric acid used in SPM cleaning, but metal silicide (specifically, molybdenum silicide) is less likely to be eluted by sulfuric acid. This improves chemical resistance during the mask blank manufacturing process, mask manufacturing process, and mask use, thereby preventing film peeling due to elution of the multilayer reflective film 12. As a result, the occurrence of defects on the multilayer reflective film or absorber film due to film peeling of the multilayer reflective film 12 can be reduced.

[0049] In this specification, the outermost peripheral portion of the multilayer reflective film 12 is preferably within a range of 20 mm from the outermost end of the multilayer reflective film 12 toward the inside, more preferably within a range of 10 mm, and even more preferably within a range of 6 mm.

[0050] The proportions of Si and transition metals in the compounds contained in the outermost periphery of the multilayer reflective film 12 can be adjusted, for example, by the incident angle and energy of sputtered particles when depositing the high refractive index layer and the low refractive index layer. The incident angle and energy of sputtered particles when depositing the high refractive index layer and the low refractive index layer can be adjusted by the angle of the substrate and the angle of the sputtering target when depositing the high refractive index layer and the low refractive index layer.

[0051] In this specification, "substrate angle" refers to the angle formed by lines L1 and L2 in Figure 7. Line L1 is a line connecting the center P1 of the main surface of substrate 10 and the center of the surface of sputtering target TG. Line L2 is a line (normal line) that passes through center P1 of the main surface of substrate 10 and is perpendicular to the main surface of substrate 10. In Figure 7, the direction in which substrate 10 is rotated clockwise is considered to be a positive angle.

[0052] In this specification, "angle of the sputtering target" refers to the angle formed by lines L3 and L4 in Figure 8. Line L3 is a line connecting the center P2 of the surface of the sputtering target TG and the center of the surface of the beam grid BG of the ion beam source BS. Line L4 is a line (normal) that passes through the center P2 of the surface of the sputtering target TG and is perpendicular to the surface of the sputtering target TG. In Figure 8, the direction in which the sputtering target TG is rotated clockwise is considered to be a positive angle.

[0053] The ratio of Si and transition metal in the compound contained in the outermost periphery of the multilayer reflective film 12 can be adjusted by adjusting the angle of the substrate and the angle of the sputtering target. More specifically, when forming a low refractive index layer, the angle of the substrate is preferably 20 degrees or more and 45 degrees or less, and the angle of the sputtering target is preferably 45 degrees or more and 65 degrees or less. When forming a high refractive index layer, the angle of the substrate is preferably 20 degrees or more and 45 degrees or less, and the angle of the sputtering target is preferably 45 degrees or more and 65 degrees or less.

[0054] <Protective film> The multilayer reflective film coated substrate 100 of this embodiment may have a protective film 14 on the multilayer reflective film 12. The protective film 14 has a function of protecting the multilayer reflective film 12 from dry etching and cleaning in the manufacturing process of the reflective mask 200, which will be described later. The protective film 14 also has a function of protecting the multilayer reflective film 12 when repairing opacity defects in a transfer pattern using an electron beam (EB). By forming the protective film 14 on the multilayer reflective film 12, damage to the surface of the multilayer reflective film 12 during manufacturing of the reflective mask 200 can be suppressed. As a result, the reflectivity characteristics of the multilayer reflective film 12 for EUV light are improved.

[0055] The protective film 14 can be formed by a known method. Examples of methods for forming the protective film 14 include ion beam sputtering, magnetron sputtering, reactive sputtering, chemical vapor deposition (CVD), and vacuum deposition. The protective film 14 may be formed by ion beam sputtering continuously after the formation of the multilayer reflective film 12.

[0056] The protective film 14 can be formed of a material with etching selectivity different from that of the absorber film 24 (described later). Examples of materials that can be used for the protective film 14 include Ru, Ru—(Nb, Rh, Zr, Y, B, Ti, La, Mo), Si—(Ru, Rh, Cr, B), Rh, Si, Zr, Nb, La, and B. Among these, using a material containing ruthenium (Ru) improves the reflectivity characteristics of the multilayer reflective film 12. Specifically, Ru and Ru—(Nb, Rh, Zr, Y, B, Ti, La, Mo) are preferred. Such a protective film 14 is particularly effective when the absorber film 24 is made of a Ta-based material and patterned by dry etching with a Cl-based gas.

[0057] Fig. 2 is a cross-sectional schematic diagram showing an example of a reflective mask blank 110 of this embodiment. The reflective mask blank 110 shown in Fig. 2 has an absorber film 24 for absorbing EUV light on the protective film 14 of the above-mentioned multilayer reflective film coated substrate 100. The reflective mask blank 110 can further have another thin film, such as a resist film 26, on the absorber film 24.

[0058] 3 is a cross-sectional schematic view showing another example of the reflective mask blank 110 of this embodiment. As shown in FIG. 3, the reflective mask blank 110 may further have an etching mask film 28 between the absorber film 24 and the resist film 26.

[0059] When a resist film 26 is formed on an absorber film 24, the resist film 26 is usually removed from the peripheral edge of the substrate where no mask pattern is formed (edge ​​rinse). When the peripheral edge of the resist film 26 is removed, the underlying absorber film 24 is exposed. In the mask manufacturing process, the exposed absorber film 24 is removed by etching, exposing the multilayer reflective film 12 underlying the absorber film 24. If the multilayer reflective film 12 is exposed, the multilayer reflective film 12 may be damaged during the mask manufacturing process and cleaning during use of the mask. For this reason, it is preferable that the outer edge of the resist film 26 after removal by edge rinse is located above the outermost periphery of the multilayer reflective film 12. This configuration more effectively prevents the multilayer reflective film 12 from being damaged and peeling off during the mask manufacturing process and cleaning during use of the mask.

[0060] <Absorbent membrane> The absorber film 24 of the reflective mask blank 110 of this embodiment is formed on the protective film 14. The basic function of the absorber film 24 is to absorb EUV light. The absorber film 24 may be an absorber film 24 designed to absorb EUV light, or an absorber film 24 with a phase shift function that also takes into account the phase difference of EUV light. The absorber film 24 with a phase shift function absorbs EUV light and reflects a portion of it to shift its phase. That is, in a reflective mask 200 patterned with an absorber film 24 with a phase shift function, the absorber film 24 absorbs and attenuates EUV light in the region where it is formed, while reflecting a portion of the light at a level that does not adversely affect pattern transfer. Furthermore, in the region (field portion) where the absorber film 24 is not formed, the EUV light is reflected by the multilayer reflective film 12 via the protective film 14. Therefore, a desired phase difference is generated between the light reflected from the absorber film 24 with a phase shift function and the light reflected from the field portion. The absorber film 24 having a phase shift function is preferably formed so that the phase difference between the light reflected from the absorber film 24 and the light reflected from the multilayer reflective film 12 is 170 to 260 degrees. Light beams with an inverted phase difference of approximately 180 degrees interfere with each other at the pattern edge, improving the image contrast of the projected optical image. This improvement in image contrast increases the resolution and makes it possible to increase various exposure latitudes, such as exposure dose latitude and focus latitude.

[0061] The absorber film 24 may be a single-layer film or a multilayer film consisting of multiple films (e.g., a lower-layer absorber film and an upper-layer absorber film). In the case of a single-layer film, the number of steps in mask blank manufacturing can be reduced, improving production efficiency. In the case of a multilayer film, the optical constants and film thickness of the upper-layer absorber film can be appropriately set so that it serves as an anti-reflection film during optical mask pattern defect inspection. This improves inspection sensitivity during optical mask pattern defect inspection. Furthermore, using a film containing oxygen (O) or nitrogen (N), which improves oxidation resistance, as the upper-layer absorber film improves stability over time. Thus, by forming the absorber film 24 into a multilayer film, various functions can be added to the absorber film 24. When the absorber film 24 has a phase shift function, forming it into a multilayer film can widen the range of optical adjustment, making it easier to obtain a desired reflectance.

[0062] The material of the absorber film 24 is not particularly limited as long as it has the function of absorbing EUV light, can be processed by etching or the like (preferably by dry etching with a chlorine (Cl)-based gas and / or a fluorine (F)-based gas), and has a high etching selectivity relative to the protective film 14. As a material having such a function, at least one metal selected from palladium (Pd), silver (Ag), platinum (Pt), gold (Au), iridium (Ir), tungsten (W), chromium (Cr), cobalt (Co), manganese (Mn), tin (Sn), tantalum (Ta), vanadium (V), nickel (Ni), hafnium (Hf), iron (Fe), copper (Cu), tellurium (Te), zinc (Zn), magnesium (Mg), germanium (Ge), aluminum (Al), rhodium (Rh), ruthenium (Ru), molybdenum (Mo), niobium (Nb), titanium (Ti), zirconium (Zr), yttrium (Y), and silicon (Si), or a compound thereof, can be preferably used.

[0063] The absorber film 24 can be formed by magnetron sputtering such as DC sputtering and RF sputtering. For example, the absorber film 24 made of a tantalum compound or the like can be formed by reactive sputtering using a target containing tantalum and boron and argon gas to which oxygen or nitrogen is added.

[0064] The tantalum compound for forming the absorber film 24 includes an alloy of Ta and the above-mentioned metals. When the absorber film 24 is a Ta alloy, the crystalline state of the absorber film 24 is preferably an amorphous or microcrystalline structure in terms of smoothness and flatness. If the surface of the absorber film 24 is not smooth or flat, the edge roughness of the absorber pattern 24a may increase, resulting in poor dimensional accuracy of the pattern. The surface roughness of the absorber film 24 is preferably 0.5 nm or less, more preferably 0.4 nm or less, and even more preferably 0.3 nm or less, in root-mean-square roughness (Rms).

[0065] Examples of tantalum compounds for forming the absorber film 24 include compounds containing Ta and B, compounds containing Ta and N, compounds containing Ta, O and N, compounds containing Ta and B and further containing at least one of O and N, compounds containing Ta and Si, compounds containing Ta, Si and N, compounds containing Ta and Ge, and compounds containing Ta, Ge and N.

[0066] Ta has a large absorption coefficient for EUV light and is a material that can be easily dry-etched with a chlorine-based gas or a fluorine-based gas. Therefore, Ta can be said to be a material with excellent processability for the absorber film 24. Furthermore, by adding B, Si, and / or Ge, etc. to Ta, an amorphous material can be easily obtained. As a result, the smoothness of the absorber film 24 can be improved. Furthermore, by adding N and / or O to Ta, the resistance of the absorber film 24 to oxidation is improved, thereby improving stability over time.

[0067] <Etching mask film> An etching mask film 28 may be formed on the absorber film 24. The material of the etching mask film 28 is preferably one that has a high etching selectivity of the absorber film 24 to the etching mask film 28. The etching selectivity of the absorber film 24 to the etching mask film 28 is preferably 1.5 or more, and more preferably 3 or more.

[0068] The reflective mask blank 110 of this embodiment preferably has an etching mask film 28 containing chromium (Cr) on the absorber film 24. Chromium or a chromium compound is preferably used as the material for the etching mask film 28. Examples of chromium compounds include materials containing Cr and at least one element selected from N, O, C, and H. The etching mask film 28 more preferably contains CrN, CrO, CrC, CrON, CrOC, CrCN, or CrOCN, and further preferably is a CrO-based film containing chromium and oxygen (a CrO film, a CrON film, a CrOC film, or a CrOCN film).

[0069] Tantalum or a tantalum compound is preferably used as the material of the etching mask film 28. Examples of tantalum compounds include a material containing Ta and at least one element selected from N, O, B, and H. More preferably, the etching mask film 28 contains TaN, TaO, TaON, TaBN, TaBO, or TaBON.

[0070] Silicon or a silicon compound is preferably used as the material for the etching mask film 28. Examples of silicon compounds include a material containing Si and at least one element selected from N, O, C, and H, as well as metal silicon (metal silicide) and metal silicon compound (metal silicide compound) in which silicon and silicon compounds contain a metal. Examples of metal silicon compounds include a material containing a metal, Si, and at least one element selected from N, O, C, and H.

[0071] The thickness of the etching mask film 28 is preferably 3 nm or more in order to form a pattern with high precision in the absorber film 24. Moreover, the thickness of the etching mask film 28 is preferably 15 nm or less in order to make the thickness of the resist film 26 thin.

[0072] <Backside conductive film> A backside conductive film 22 for electrostatic chuck may be formed on the backside of the substrate 100 (the surface opposite to the surface on which the multilayer reflective film 12 is formed). The sheet resistance required for the backside conductive film 22 for electrostatic chuck use is typically 100 Ω / □ (Ω / square) or less. The backside conductive film 22 can be formed, for example, by magnetron sputtering or ion beam sputtering using a target of a metal such as chromium or tantalum, or an alloy thereof. The material for the backside conductive film 22 is preferably a material containing chromium (Cr) or tantalum (Ta). For example, the material for the backside conductive film 22 is preferably a Cr compound containing Cr and at least one element selected from boron, nitrogen, oxygen, and carbon. Examples of Cr compounds include CrN, CrON, CrCN, CrCON, CrBN, CrBON, CrBCN, and CrBOCN. The material of the back surface conductive film 22 is preferably 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 Ta compounds include TaB, TaN, TaO, TaON, TaCON, TaBN, TaBO, TaBON, TaBCON, TaHf, TaHfO, TaHfN, TaHfON, TaHfCON, TaSi, TaSiO, TaSiN, TaSiON, and TaSiCON.

[0073] The thickness of the back surface conductive film 22 is not particularly limited as long as it functions as a film for an electrostatic chuck, but is, for example, 10 nm to 200 nm.

[0074] <Method of manufacturing a reflective mask> The reflective mask blank 110 of this embodiment can be used to manufacture the reflective mask 200 of this embodiment. An example of a method for manufacturing a reflective mask will now be described.

[0075] 4a-f are schematic diagrams showing an example of a method for manufacturing a reflective mask 200. As shown in FIGS. 4a-f, first, a reflective mask blank 110 is prepared, which includes a substrate 10, a multilayer reflective film 12 formed on the front surface of the substrate 10, a protective film 14 formed on the multilayer reflective film 12, an absorber film 24 formed on the protective film 14, and a back surface conductive film 22 formed on the back surface of the substrate 10 (FIG. 4a). Next, a resist film 26 is formed on the absorber film 24 (FIG. 4b). To prevent dust generation due to peeling of the resist film 26 from the peripheral edge 27 of the substrate, the resist film 26 from the peripheral edge 27 of the substrate is removed with a solvent that dissolves the resist film 26 (edge ​​rinse) (FIG. 4c). A pattern is written on the resist film 26 using an electron beam lithography system, and a resist pattern 26a is formed by further undergoing a development and rinsing process (FIG. 4d).

[0076] Using the resist pattern 26a as a mask, the absorber film 24 is dry-etched, whereby the portions of the absorber film 24 that are not covered by the resist pattern 26a are etched, and an absorber pattern 24a is formed (FIG. 4e).

[0077] The etching gas for the absorber film 24 may be, for example, a fluorine-based gas and / or a chlorine-based gas. Examples of the fluorine-based gas include CF4, CHF3, C2F6, C3F6, C4F6, C4F8, CH2F2, CH3F, C3F8, SF6, and F2. Examples of the chlorine-based gas include Cl2, SiCl4, CHCl3, CCl4, and BCl3. Alternatively, a mixed gas containing a fluorine-based gas and / or a chlorine-based gas and O2 at a predetermined ratio may be used. These etching gases may further contain an inert gas such as He and / or Ar, as necessary.

[0078] After the absorber pattern 24a is formed, the resist pattern 26a is removed with a resist remover. After the resist pattern 26a is removed, a wet cleaning process is performed using an acidic or alkaline aqueous solution, thereby obtaining the reflective mask 200 of this embodiment (FIG. 4f).

[0079] In addition, when a reflective mask blank 110 in which an etching mask film 28 is formed on the absorber film 24 is used, an additional process is performed in which a pattern (etching mask pattern) is formed on the etching mask film 28 using the resist pattern 26a as a mask, and then a pattern is formed on the absorber film 24 using the etching mask pattern as a mask.

[0080] The reflective mask 200 thus obtained has a structure in which a multilayer reflective film 12, a protective film 14, and an absorber pattern 24a are laminated on a substrate 10.

[0081] An area 30 where the multilayer reflective film 12 (including the protective film 14) is exposed has the function of reflecting EUV light. An area 32 where the multilayer reflective film 12 (including the protective film 14) is covered with the absorber pattern 24a has the function of absorbing EUV light. According to the reflective mask 200 of this embodiment, the thickness of the absorber pattern 24a can be made thinner than conventional so that the reflectance becomes, for example, 2.5% or less, and therefore a finer pattern can be transferred to a transfer target object.

[0082] <Method of manufacturing a semiconductor device> A transfer pattern can be formed on a semiconductor substrate by lithography using the reflective mask 200 of this embodiment. This transfer pattern has a shape that is the result of transferring the pattern of the reflective mask 200. By forming a transfer pattern on a semiconductor substrate using the reflective mask 200, a semiconductor device can be manufactured.

[0083] A method for transferring a pattern onto a semiconductor substrate 56 with a resist by using EUV light will be described with reference to FIG.

[0084] 5 shows a pattern transfer apparatus 50. The pattern transfer apparatus 50 includes a laser plasma X-ray source 52, a reflective mask 200, and a reduction optical system 54. An X-ray reflection mirror is used as the reduction optical system 54.

[0085] The pattern reflected by the reflective mask 200 is reduced, typically to about 1 / 4, by the reduction optical system 54. For example, a wavelength band of 13 to 14 nm is used as the exposure wavelength, and the optical path is preset to be in a vacuum. Under these conditions, EUV light generated by the laser plasma X-ray source 52 is made incident on the reflective mask 200. The light reflected by the reflective mask 200 is transferred onto a semiconductor substrate 56 with a resist via the reduction optical system 54.

[0086] Light reflected by the reflective mask 200 enters the reduction optical system 54. The light that enters the reduction optical system 54 forms a transfer pattern on the resist film on the resist-coated semiconductor substrate 56. By developing the exposed resist film, a resist pattern can be formed on the resist-coated semiconductor substrate 56. By etching the semiconductor substrate 56 using the resist pattern as a mask, it is possible to form, for example, a predetermined wiring pattern on the semiconductor substrate. A semiconductor device can be manufactured through these and other necessary steps. [Example]

[0087] Examples 1 to 5 and Comparative Example 1 will be described below with reference to the drawings.

[0088] (Substrate 100 with multilayer reflective film) First, a substrate 10 having a polished main surface and a size of 6025 (approximately 152 mm × 152 mm × 6.35 mm) was prepared. This substrate 10 was made of low-thermal expansion glass (SiO2-TiO2-based glass). The main surface of the substrate 10 was polished through a rough polishing process, a precision polishing process, a local polishing process, and a touch polishing process.

[0089] Next, a multilayer reflective film 12 was formed on the main surface of the substrate 10. The multilayer reflective film 12 formed on the substrate 10 was a periodic multilayer reflective film 12 made of Mo and Si to be suitable for EUV light with a wavelength of 13.5 nm. The multilayer reflective film 12 was formed by alternately stacking Mo and Si films on the substrate 10 using an ion beam sputtering method with a Mo target and a Si target and krypton (Kr) as the process gas. First, a Si film was deposited to a thickness of 4.2 nm, followed by a Mo film to a thickness of 2.8 nm. This constitutes one cycle, and after 40 cycles were similarly stacked, a Si film was finally deposited to a thickness of 4.0 nm. When forming the multilayer reflective film 12 by ion beam sputtering, the substrate angle and sputtering target angle were set as shown in Table 1 below.

[0090] [Table 1]

[0091] Furthermore, in Comparative Example 1, laser light was irradiated onto the outermost peripheral portion of the multilayer reflective film 12. A CO2 laser (CW, wavelength 10.6 μm, output 3 W) was used for the laser light irradiation. The laser light was irradiated under the condition of an irradiation time of 300 ms by scanning a focused beam so that the irradiation beam diameter of the laser light was φ200 μm. The laser light was irradiated within a range of 6 mm from the outermost edge of the multilayer reflective film 12.

[0092] In Examples 1 to 3, after the formation of the multilayer reflective film 12, a Ru protective film 14 (thickness: 2.5 nm) was further formed continuously on the multilayer reflective film 12 by ion beam sputtering. When the Ru protective film 14 was formed by ion beam sputtering, the angle of incidence of Ru sputtered particles with respect to the normal to the main surface of the substrate 10 was set to 40 degrees, and the gas flow rate of the ion source was set to 8 sccm. In Examples 4 and 5, after the formation of the multilayer reflective film 12, the substrate with the multilayer reflective film was temporarily removed from the chamber into the atmosphere, and the Ru protective film 14 was formed discontinuously with the formation of the multilayer reflective film 12. The Ru protective film 14 was formed to a thickness of 2.5 nm by DC magnetron sputtering using a Ru target in an Ar gas atmosphere.

[0093] In the above-described Examples 1 to 5 and Comparative Example 1, when forming the multilayer reflective film 12 and the protective film 14, the substrate 10 was held using a mechanical chuck device to form the multilayer reflective film 12. Therefore, the multilayer reflective film 12 formed on the main surface of the substrate 10 did not wrap around to the end face of the substrate 10, and was not formed on the outer periphery of the main surface of the substrate 10.

[0094] In this manner, the multilayer reflective film coated substrates 100 of Examples 1 to 5 and Comparative Example 1 were produced.

[0095] (Reflective mask blank 110) Next, a reflective mask blank 110 was produced using the above-mentioned multilayer reflective film coated substrate 100. A method for producing the reflective mask blank 110 will be described below.

[0096] An absorber film 24 was formed on the protective film 14 of the multilayer reflective film-coated substrate 100 by DC magnetron sputtering. The absorber film 24 was a laminated film consisting of two layers: a TaN film serving as an absorption layer and a TaO film serving as a low-reflection layer. A TaN film was formed as an absorption layer on the surface of the protective film 14 of the multilayer reflective film-coated substrate 100 by DC magnetron sputtering. This TaN film was formed by reactive sputtering in a mixed gas atmosphere of Ar gas and N gas, with the multilayer reflective film-coated substrate 100 facing a Ta target. Next, a TaO film (low-reflection layer) was formed on the TaN film by DC magnetron sputtering. Like the TaN film, this TaO film was formed by reactive sputtering in a mixed gas atmosphere of Ar and O2, with the multilayer reflective film-coated substrate 100 facing a Ta target.

[0097] The composition (atomic ratio) of the TaN film was Ta:N=70:30, and the thickness was 48 nm.The composition (atomic ratio) of the TaO film was Ta:O=35:65, and the thickness was 11 nm.

[0098] Next, a back surface conductive film 22 made of CrN was formed on the back surface of the substrate 10 by magnetron sputtering (reactive sputtering) under the following conditions. Conditions for forming the back surface conductive film 22: Cr target, mixed gas atmosphere of Ar and N2 (Ar: 90 atomic %, N: 10 atomic %), film thickness 20 nm.

[0099] When forming the absorber film 24 and the back surface conductive film 22 described above, the absorber film 24 and the back surface conductive film 22 were formed while shielding a part of the outer periphery of the substrate 10 so that the absorber film 24 and the back surface conductive film 22 would not wrap around the edge face of the substrate 10.

[0100] In this manner, the reflective mask blanks 110 of Examples 1 to 5 and Comparative Example 1 were produced.

[0101] (Evaluation of reflective mask blank 110) The cross section of the outermost peripheral portion of the multilayer reflective film 12 of the reflective mask blank 110 produced in Examples 1 to 5 was observed by TEM. FIG. 6 is a schematic diagram showing an enlarged cross section of the outermost peripheral portion 60 of the multilayer reflective film 12 of the reflective mask blank 110. As shown in FIG. 6, the interface between the Mo layer and the Si layer was absent in the outermost peripheral portion 60 of the multilayer reflective film 12. It was also confirmed that a compound made of molybdenum silicide was formed in the outermost peripheral portion 60 of the multilayer reflective film 12. It was also confirmed that the thickness of the outermost peripheral portion 60 of the multilayer reflective film 12 gradually decreased from the center of the substrate 10 toward the outside.

[0102] For the reflective mask blanks 110 of Examples 1 to 5 and Comparative Example 1, the compositions of the outermost periphery 60 of the multilayer reflective film 12 were analyzed by TEM-EDX, and the results are shown in Table 2 below.

[0103] [Table 2]

[0104] SPM cleaning was performed on the reflective mask blanks 110 of Examples 1 to 5 and Comparative Example 1. The cleaning conditions were as follows. Cleaning solution: H2SO4:H2O2 = 2:1 (weight ratio) Washing temperature: 120℃ Washing time: 10 minutes

[0105] The reflective mask blanks 110 of Examples 1 to 5 and Comparative Example 1 after cleaning were subjected to defect inspection in a 132 mm × 132 mm area on the surface of the absorber film 24 using a high-sensitivity defect inspection device with an inspection light source wavelength of 355 nm ("MAGICS series" manufactured by Lasertec Corporation). As a result, no defects were detected in the reflective mask blanks 110 of Examples 1 to 5 and Comparative Example 1.

[0106] Next, a resist film 26 was formed on the absorber film 24 in the reflective mask blanks 110 of Examples 1 to 5 and Comparative Example 1. Thereafter, the resist film 26 on the periphery of the substrate was removed with a solvent that dissolves the resist film 26, thereby producing a reflective mask blank from which the resist film 26 on the periphery of the substrate had been removed.

[0107] Next, defects caused by peeling of the multilayer reflective film due to cleaning during the mask manufacturing process and during mask use were evaluated.

[0108] For the reflective mask blank from which the resist film 26 on the peripheral edge of the substrate was removed, the absorber film 24 was removed by etching using the resist film 24 as a mask. Specifically, using the resist film 24 as a mask, the exposed region of the absorber film 24 was removed by etching.

[0109] After that, the SPM cleaning was carried out under the same conditions as above.

[0110] As described above, the reflective mask blanks of Examples 1 to 5 and Comparative Example 1 after cleaning were subjected to defect inspection in a 132 mm x 132 mm area on the surface of the absorber film 24 using a highly sensitive defect inspection device ("MAGICS Series" manufactured by Lasertec Corporation) with an inspection light source wavelength of 355 nm.

[0111] As a result of the defect inspection, the number of detected defects was 2 in the reflective mask blank 110 of Example 1. The number of detected defects was 0 in the reflective mask blanks 110 of Examples 2 to 5. In contrast, the number of detected defects was 20 in the reflective mask blank 110 of Comparative Example 1.

[0112] In the reflective mask blank 110 of Comparative Example 1, more defects were detected on the surface of the absorber film 24 than in Examples 1 to 5. The reason for this result is thought to be that the reflective mask blank 110 of Comparative Example 1 had a higher Si content in the outermost peripheral portion 60 of the multilayer reflective coating 12. That is, a silicide film with a high Si content has a high compressive stress, which is thought to be the cause of more film peeling of the multilayer reflective coating and defects on the absorber film caused by film peeling. In contrast, in the reflective mask blanks 110 of Examples 1 to 5, the Si content in the outermost peripheral portion 60 of the multilayer reflective coating 12 was low, which reduced the compressive stress in the outermost peripheral portion 60, and it is thought that this reduced the occurrence of defects on the absorber film 24 caused by film peeling of the multilayer reflective coating 12.

[0113] Therefore, when a reflective mask 200 is produced using the reflective mask blanks 110 of Examples 1 to 5, it is possible to reduce the occurrence of defects on the multilayer reflective film or absorber film caused by peeling of the multilayer reflective film 12 during the mask manufacturing process or cleaning during mask use. On the other hand, in the case of Comparative Example 1, peeling of the multilayer reflective film occurs during the mask manufacturing process or cleaning during mask use, and it is thought that many defects on the multilayer reflective film or absorber film caused by peeling of the multilayer reflective film occur.

[0114] (Fabrication of the reflective mask 200) In addition to the reflective mask blanks used to evaluate defects caused by peeling of the multilayer reflective film described above, reflective mask blanks 110 of Examples 1 to 5 and Comparative Example 1 were prepared. Next, a resist film 26 was formed on the absorber film 24 of the reflective mask blank 110, and then the resist film 26 on the periphery of the substrate was removed. Next, a pattern was written and developed on the resist film 26 using an electron beam lithography device to form a resist pattern 20a. Thereafter, the absorber film 24 was dry-etched using the resist pattern 20a as a mask to form an absorber pattern 24a. In this manner, a reflective mask 200 was produced.

[0115] The reflective mask 200 thus obtained was subjected to mask cleaning by SPM cleaning. The reflective mask 200 was subjected to defect inspection using a highly sensitive defect inspection device capable of detecting defects with a sphere equivalent volume diameter (SEVD) of 21.5 nm. No defects due to film peeling of the multilayer reflective film 12 were detected on the multilayer reflective film 12 of the reflective mask 200 or on the absorber pattern 24a.

[0116] On the other hand, when a defect inspection was performed on a reflective mask manufactured using the reflective mask blank of Comparative Example 1, 14 defects caused by film peeling of the multilayer reflective film 12 were detected on the multilayer reflective film 12 and on the absorber pattern 24a. [Explanation of symbols]

[0117] 10 Substrate 12 Multilayer reflective film 14 Protective film 22 Backside conductive film 24 absorber membrane 26 Resist film 28 Etching mask film 60 outermost part 100 Multilayer reflective film substrate 110 Reflective mask blank 200 Reflective Mask

Claims

1. A multilayer reflective film coated substrate including a substrate and a multilayer reflective film formed on a main surface of the substrate, the multilayer reflective film has a structure in which high refractive index layers and low refractive index layers are alternately stacked, the high-refractive-index layer is made of a material containing Si, and the low-refractive-index layer is made of a material containing a transition metal, the outermost periphery of the multilayer reflective film is made of a compound containing Si and a transition metal, The multilayer reflective film-coated substrate is characterized in that the ratio of the content (atomic %) of Si to the total content (atomic %) of Si and the transition metal in the compound is 0.50 or less.

2. 2. The substrate with a multilayer reflective film according to claim 1, wherein the compound contains oxygen.

3. 3. The multilayer reflective film coated substrate according to claim 2, wherein the content of said oxygen in said compound is 0.5 atomic % or more and 75 atomic % or less.

4. 4. The multilayer reflective film coated substrate according to claim 1, wherein a protective film is formed on the multilayer reflective film.

5. A reflective mask blank having a multilayer reflective film formed on a main surface of a substrate, the multilayer reflective film being formed by alternately stacking high refractive index layers and low refractive index layers, and an absorber film, the high-refractive-index layer in the multilayer reflective film is made of a material containing Si, and the low-refractive-index layer is made of a material containing a transition metal, an outermost periphery of the multilayer reflective film formed on the main surface is made of a compound containing Si and a transition metal; A reflective mask blank, wherein the ratio of the content (atomic %) of Si to the total content (atomic %) of Si and the transition metal in the compound is 0.50 or less.

6. 6. The reflective mask blank according to claim 5, wherein the compound contains oxygen.

7. 7. The reflective mask blank according to claim 6, wherein the content of said oxygen in said compound is 0.5 atomic % or more and 75 atomic % or less.

8. 8. The reflective mask blank according to claim 5, wherein a protective film made of a material having an etching selectivity different from that of the absorber film is formed between the multilayer reflective film and the absorber film.

9. 9. The reflective mask blank according to claim 5, wherein a resist film is formed on the absorber film.

10. 10. The reflective mask blank according to claim 9, wherein an outer peripheral edge of the resist film is located above the outermost peripheral portion of the multilayer reflective film made of the compound.

11. A method for manufacturing a reflective mask, comprising: preparing a reflective mask blank according to claim 9; and patterning the absorber film to form an absorber pattern on the multilayer reflective film.

12. 12. A method for manufacturing a semiconductor device, comprising the step of transferring an absorber pattern onto a resist film on a semiconductor substrate using a reflective mask obtained by the method for manufacturing a reflective mask according to claim 11.

Images