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

Abstract

Provided is a substrate with a multilayer reflective film, which enables highly accurate management of defect coordinates without increasing reference mark measurement time.　The substrate with a multilayer reflective film comprises a substrate and a multilayer reflective film disposed on the substrate. The substrate with a multilayer reflective film is characterized in that one or a plurality of marks are formed outside a transfer pattern formation region on said substrate, and there are a plurality of reference points extracted from these marks in a 460x460 μm region.

Description

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

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

[0002] In recent years, with the increasing integration density of semiconductor devices in the semiconductor industry, there has been a demand for finer patterns that exceed the transfer limit of conventional photolithography using ultraviolet light. To enable the formation of such fine patterns, EUV lithography, an exposure technology using extreme ultraviolet (EUV) light, has been developed. Here, EUV light refers to light in the wavelength range of the soft X-ray or vacuum ultraviolet region, specifically light with a wavelength of approximately 0.2 to 100 nm. A reflective mask is a transfer mask used in EUV lithography. Such a reflective mask has a multilayer reflective film formed on a substrate that reflects exposure light, and an absorber film formed on the multilayer reflective film that absorbs exposure light. A transfer pattern is formed in the absorber film.

[0003] In a reflective mask that uses EUV light as exposure light, it is particularly important to accurately identify the location of a defect on the multilayer reflective film, because defects present in the multilayer reflective film are almost impossible to correct and can result in serious phase defects in the transferred pattern.

[0004] Furthermore, a technology (Defect Mitigation Technology, referred to in this specification as "DM technology") is used in which writing data is corrected based on defect data and device pattern data of the mask blank so that an absorber pattern is formed where a defect exists, thereby mitigating the effect of the defect. In the DM technology, for example, in a reflective mask blank in which an absorber film is formed on a multilayer reflective film, when a pattern is written on a resist film formed on the absorber film using an electron beam writing apparatus, the electron beam writing apparatus also detects reference marks (fiducial marks or alignment marks) with an electron beam. In the DM technology, a pattern is written on the resist film based on writing data corrected and modified based on the reference points detected by the electron beam writing apparatus.

[0005] For example, Patent Documents 1 and 2 describe examples of substrates with reflective films that are provided with reference marks for DM technology.

[0006] Patent Document 1 describes an example of a substrate with a reflective layer, which has a substrate and a reflective layer on the substrate that reflects EUV light, and in which at least three marks are formed on the surface of the reflective layer. The requirements are that each of these marks has a sphere-equivalent diameter of 30 to 100 nm, and that the three marks do not lie on the same imaginary straight line on the deposition surface.

[0007] Furthermore, Patent Document 2 describes an example in which 28 fiducial marks are formed outside a 132 mm × 132 mm pattern formation area on a multilayer reflective film-coated substrate having a substrate and a multilayer reflective film on the substrate that reflects EUV light. In this example, the number of fiducial marks is determined by the following procedure: First, a conversion coefficient is calculated for coordinate conversion from the coordinate system of a defect inspection device (first coordinate system) to the coordinate system of a coordinate measuring device (second coordinate system). Next, the calculated conversion coefficient is used to convert first defect coordinates acquired by the defect inspection device into third defect coordinates based on the second coordinate system of the coordinate measuring device. Then, the number of fiducial marks is determined so that the deviation 3σ between the second defect coordinates actually acquired by the coordinate measuring device and the converted third defect coordinates is less than 50 nm.

[0008] International Publication No. WO 2008 / 129914 International Publication No. WO 2020 / 095959

[0009] In the above-described DM technique, it is necessary to convert defect coordinates acquired by a defect inspection device into the coordinate system of an electron beam lithography device. A coordinate measuring device is used to convert the coordinate system of the defect inspection device into the coordinate system of the electron beam lithography device. Therefore, if the alignment accuracy between the defect inspection device and the coordinate measuring device is poor, the coordinate system of the defect inspection device cannot be converted into the coordinate system of the electron beam lithography device with high accuracy. Furthermore, if the accuracy of this conversion is poor, the problem arises that when the DM technique is implemented, it is not possible to perform high-accuracy correction and modification of the lithography data.

[0010] As with the technology described in Patent Document 2, the more reference marks there are on the film-forming surface of the substrate, the more accurate the coordinate measurement can be achieved by statistical correction processing such as the least squares method. However, if an excessively large number of reference marks are arranged over a wide area on the substrate, another problem arises in that it takes a long time to detect the reference marks.

[0011] Therefore, an object of the present invention is to provide a substrate with a multilayer reflective film, a reflective mask blank, and a reflective mask that can control defect coordinates with high precision without increasing the measurement time of fiducial marks. Another object of the present invention is to provide a method for manufacturing a high-quality semiconductor device that eliminates the influence of defects in the transfer pattern by using a reflective mask in which defect coordinates are controlled with high precision.

[0012] In order to solve the above problems, the present invention has the following configuration.

[0013] (Configuration 1) Configuration 1 is a multilayer reflective film-coated substrate having a substrate and a multilayer reflective film disposed on the substrate, in which one or more marks are formed outside a transfer pattern formation area on the multilayer reflective film-coated substrate, and a plurality of reference points extracted from the one or more marks are present within any area surrounded by 460 μm × 460 μm.

[0014] (Configuration 2) Configuration 2 is the multilayer reflective film-coated substrate of configuration 1, in which the number of the reference points extracted in any region surrounded by 460 μm×460 μm is 3 or more and 50 or less.

[0015] (Configuration 3) Configuration 3 is the multilayer reflective film coated substrate of configuration 1 or 2, in which at least one reference point is extracted based on the positional relationship between two or more of the marks.

[0016] (Configuration 4) Configuration 4 is the multilayer reflective film-coated substrate of any one of Configurations 1 to 3, wherein at least one of the marks includes a cross pattern or a composite pattern of a plurality of cross patterns.

[0017] (Configuration 5) Configuration 5 is the multilayer reflective film-coated substrate of any one of configurations 1 to 3, wherein at least one of the marks includes a cross pattern, and the other marks include a polygonal, circular, or elliptical pattern.

[0018] (Configuration 6) Configuration 6 is a reflective mask blank having a substrate, a multilayer reflective film disposed on the substrate, and a thin film for transfer pattern formation disposed on the multilayer reflective film, wherein one or more marks are formed outside a transfer pattern formation region on the reflective mask blank, and a plurality of reference points extracted from the one or more marks are present within any region surrounded by 460 μm × 460 μm.

[0019] (Configuration 7) Configuration 7 is the reflective mask blank of configuration 6, wherein the number of the reference points extracted in any region surrounded by 460 μm×460 μm is 3 or more and 50 or less.

[0020] (Configuration 8) Configuration 8 is the reflective mask blank of configuration 6 or 7, in which at least one reference point is extracted based on the positional relationship between two or more of the marks.

[0021] (Configuration 9) Configuration 9 is the reflective mask blank of any one of configurations 6 to 8, wherein at least one of the marks includes a cross pattern or a composite pattern of a plurality of cross patterns.

[0022] (Configuration 10) Configuration 10 is the reflective mask blank of any one of configurations 6 to 8, wherein at least one of the marks includes a cross pattern, and the other marks include a polygonal, circular, or elliptical pattern.

[0023] (Configuration 11) Configuration 11 is a reflective mask in which a transfer pattern is formed on the thin film of the reflective mask blank.

[0024] (Configuration 12) Configuration 12 is a method for manufacturing a semiconductor device, comprising a step of transferring a pattern onto a semiconductor substrate using the reflective mask of configuration 11.

[0025] According to the present invention, it is possible to provide a multilayer reflective film coated substrate, a reflective mask blank, and a reflective mask that can control defect coordinates with high precision without increasing the measurement time of the reference marks. Furthermore, according to the present invention, it is possible to provide a method for manufacturing a high-quality semiconductor device that eliminates the influence of defects in the transfer pattern by using a reflective mask in which defect coordinates are controlled with high precision.

[0026] FIG. 1 is a cross-sectional view schematically illustrating an example of a multilayer reflective film coated substrate. FIG. 2 is a cross-sectional view schematically illustrating another example of a multilayer reflective film coated substrate. FIG. 3 is a plan view of a multilayer reflective film coated substrate according to an embodiment, and an enlarged view of a fiducial mark. FIG. 4 is a cross-sectional view schematically illustrating a fiducial mark of a cross pattern. FIG. 5 is a cross-sectional view schematically illustrating a fiducial mark of a cross composite pattern. FIG. 6 is a polygonal pattern view schematically illustrating a fiducial mark having two quadrangular patterns. FIG. 7 is a cross-sectional view schematically illustrating a fiducial mark having five quadrangular patterns. FIG. 8 is a cross-sectional view schematically illustrating an example of a reflective mask blank. FIG. 9 is a cross-sectional view schematically illustrating another example of a reflective mask blank. FIG. 10 is a cross-sectional view schematically illustrating an example of a method for manufacturing a reflective mask. FIG. 11 is a cross-sectional view schematically illustrating an example of an EUV exposure apparatus. FIG. 12 is a cross-sectional view schematically illustrating a shape pattern of a fiducial mark according to an example. FIG. 13 is a cross-sectional view schematically illustrating a shape pattern of a fiducial mark according to a comparative example.

[0027] Hereinafter, embodiments of the present invention will be described in detail. Note that the following embodiments are provided for the purpose of specifically explaining the present invention, and are not intended to limit the scope of the present invention.

[0028] In this specification, the term "reflective mask blank" refers to a master used to manufacture a reflective mask 200 (see FIGS. 9 and 10).

[0029] In this specification, "thin film B is disposed (formed) on thin film A (or substrate)" not only means that thin film B is disposed (formed) in contact with the surface of thin film A (or substrate), but also means that another thin film C is present between thin film A (or substrate) and thin film B. Furthermore, in this specification, for example, "thin film B is disposed in contact with the surface of thin film A (or substrate)" means that thin film A (or substrate) and thin film B are disposed so as to be in direct contact with each other, without any other thin film interposed between them. Furthermore, in this specification, "on" does not necessarily mean the upper side in the vertical direction. "on" merely indicates the relative positional relationship between the thin film, the substrate, etc.

[0030] <Substrate with Multilayer Reflective Film> First, the substrate with multilayer reflective film 90 of this embodiment will be described.

[0031] Fig. 1 is a cross-sectional schematic diagram showing an example of a multilayer reflective film-coated substrate 90 of the present embodiment. The multilayer reflective film-coated substrate 90 of the embodiment shown in Fig. 1 has a substrate 1 and a multilayer reflective film 2 disposed on the substrate 1 on one main surface of the substrate 1. As shown in Fig. 1, the multilayer reflective film-coated substrate 90 of the present embodiment can further include a back surface conductive film 5 on the other main surface of the substrate 1.

[0032] Fig. 2 is a cross-sectional schematic diagram showing another example of a multilayer reflective film-coated substrate 90 of this embodiment. The multilayer reflective film-coated substrate 90 shown in Fig. 1 includes, on one main surface of the substrate 1, a substrate 1, a multilayer reflective film 2 disposed on the substrate 1, and a protective film 3 disposed on the multilayer reflective film 2. As shown in Fig. 2, the multilayer reflective film-coated substrate 90 of this embodiment can further include a back surface conductive film 5 on the other main surface of the substrate 1.

[0033] <<Substrate>> The substrate 1 is preferably made of a material having a low thermal expansion coefficient within the range of 0±5 ppb / °C in order to prevent distortion of the transferred pattern due to heat during exposure to EUV light. Examples of materials having a low thermal expansion coefficient within this range include SiO ２ -TiO ２ Glasses, multi-component glass ceramics, etc. can be used.

[0034] The main surface (first main surface) of the substrate 1 on which a transfer pattern (the absorber pattern 4a described below) is formed is preferably processed to increase its flatness. Increasing the flatness of the main surface of the substrate 1 can improve the positional accuracy and transfer accuracy of the pattern. For example, in the case of EUV exposure, in a 132 mm × 132 mm area of ​​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. Furthermore, the second main surface (rear surface) opposite the side on which the transfer pattern is formed is the surface fixed to the exposure apparatus by an electrostatic chuck. In a 142 mm × 142 mm area of ​​the rear surface, the flatness is 0.1 μm or less, more preferably 0.05 μm or less, and particularly preferably 0.03 μm or less. In this specification, flatness is a value representing the warpage (deformation amount) of the surface indicated by TIR (Total Indicated Reading). The flatness (TIR) ​​is the absolute value of the difference in height between the highest point on the surface of substrate 1 above the focal plane, which is determined by the least squares method using the surface of substrate 1 as a reference, and the lowest point on the surface of substrate 1 below this focal plane.

[0035] In the case of EUV exposure, the surface roughness of the main surface of the substrate 1 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 1 preferably has high rigidity to prevent deformation due to film stress of the thin films (such as the multilayer reflective film 2) formed thereon. In particular, it is preferable that the substrate 1 has a high Young's modulus of 65 GPa or more.

[0037] <<Multilayer reflective film>>

[0038] The multilayer reflective film coated substrate 90 of the embodiment includes a multilayer reflective film 2. The multilayer reflective film 2 provides the reflective mask 200 with the function of reflecting EUV light. The multilayer reflective film 2 is a multilayer film in which layers each containing elements with different refractive indices as main components are periodically stacked.

[0039] Generally, the multilayer reflective film 2 is a multilayer film in which thin films of high refractive index materials, i.e., light elements or compounds thereof (high refractive index layers), and thin films of low refractive index materials, i.e., heavy elements or compounds thereof (low refractive index layers), are alternately stacked in approximately 40 to 60 cycles.

[0040] The multilayer film used as the multilayer reflective film 2 can have a structure in which multiple periods of a high-refractive-index layer / low-refractive-index layer stacked in this order from the substrate 1 side are stacked. Alternatively, the multilayer film can have a structure in which multiple periods of a low-refractive-index layer / high-refractive-index layer stacked in this order from the substrate 1 side are stacked. The topmost layer of the multilayer reflective film 2, i.e., the surface layer of the multilayer reflective film 2 opposite the substrate 1 side, is preferably a high-refractive-index layer. In the above-described multilayer film, when multiple periods of a high-refractive-index layer / low-refractive-index layer stacked in this order from the substrate 1 side are stacked, the topmost layer is the low-refractive-index layer. In this case, if the low-refractive-index layer constitutes the topmost surface of the multilayer reflective film 2, it will be easily oxidized, thereby reducing the reflectivity of the reflective mask 200. Therefore, it is preferable to form the multilayer reflective film 2 by further forming a high-refractive-index layer on the topmost low-refractive-index layer. On the other hand, in the above-mentioned multilayer film, when a low-refractive index layer / high-refractive index layer stack structure in which a low-refractive index layer and a high-refractive index layer are stacked in this order from the substrate 1 side is defined as one cycle, and multiple cycles are stacked, the uppermost layer is the high-refractive index layer, and therefore, in this case, there is no need to form an additional high-refractive index layer.

[0041] The high-refractive index layer can be a layer containing silicon (Si). Examples of materials containing Si include elemental Si and Si compounds containing boron (B), carbon (C), nitrogen (N), oxygen (O), and / or hydrogen (H). By using a high-refractive index layer containing Si, a reflective mask 200 with excellent reflectivity for EUV light can be obtained. The low-refractive index layer can be a metal element selected from molybdenum (Mo), ruthenium (Ru), rhodium (Rh), and platinum (Pt), or an alloy thereof. These metal elements or alloys may also be doped with boron (B), carbon (C), nitrogen (N), oxygen (O), and / or hydrogen (H). In the multilayer reflective film-coated substrate 90 of this embodiment, the low-refractive index layer is preferably a molybdenum (Mo) layer, and the high-refractive index layer is preferably a silicon (Si) layer. For example, a Mo / Si periodic stacked film in which Mo layers and Si layers are alternately stacked for approximately 40 to 60 periods can be preferably used as the multilayer reflective film 2 for reflecting EUV light with a wavelength of 13 nm to 14 nm (e.g., 13.5 nm). Furthermore, in the multilayer reflective film-coated substrate 90 of this embodiment, the low refractive index layers are preferably ruthenium (Ru) layers, and the high refractive index layers are preferably silicon (Si) layers. For example, a Ru / Si periodic stacked film in which Ru layers and Si layers are alternately stacked for approximately 30 to 40 periods can be preferably used as the multilayer reflective film 2 for reflecting EUV light with a wavelength of 13 nm to 14 nm (e.g., 13.5 nm).

[0042] The reflectance of the multilayer reflective film 2 alone is usually 65% ​​or more, with the upper limit usually being 73%. The film thickness and period of each constituent layer of the multilayer reflective film 2 can be appropriately selected depending on the exposure wavelength. Specifically, the film thickness and period of each constituent layer of the multilayer reflective film 2 can be selected so as to satisfy the law of Bragg reflection. The multilayer reflective film 2 has a plurality of high refractive index layers and a plurality of low refractive index layers, but the film thicknesses of the high refractive index layers and the low refractive index layers do not necessarily have to be the same.

[0043] Methods for forming the multilayer reflective film 2 are known in the art. The multilayer reflective film 2 can be formed by depositing each layer by, for example, ion beam sputtering. In the case of the Mo / Si periodic multilayer film described above, for example, an Si film having a thickness of about 4 nm is first deposited on the substrate 1 using a Si target by ion beam sputtering or magnetron sputtering, and then an Mo film having a thickness of about 3 nm is deposited using a Mo target. This constitutes one period, and 40 to 60 periods are stacked to form the multilayer reflective film 2 (the outermost layer is a Si film). Note that, although 60 periods requires more steps than 40 periods, the reflectivity for EUV light can be increased.

[0044] <<Protective Film>> The multilayer reflective film-coated substrate 90 of this embodiment preferably has a protective film 3 on the multilayer reflective film 2. The protective film 3 is disposed in contact with the surface of the multilayer reflective film 2 opposite to the substrate 1.

[0045] In the multilayer reflective film coated substrate 90 of this embodiment, the presence of the protective film 3 on the multilayer reflective film 2 makes it possible to suppress damage to the surface of the multilayer reflective film 2 when manufacturing a reflective mask 200 (EUV mask) using the reflective mask blank 100. As a result, the resulting reflective mask 200 has good reflectance characteristics for EUV light.

[0046] The protective film 3 preferably contains at least one selected from ruthenium (Ru), rhodium (Rh), and iridium (Ir). The protective film 3 more preferably contains at least one selected from ruthenium (Ru) and rhodium (Rh). The protective film 3 may further contain an additive element in addition to the above elements. The additive element contained in the protective film 3 is preferably one or more elements selected from Tl, Hf, Ti, Zr, Mn, In, Ga, Cd, Bi, Ta, Pb, Ag, Al, V, Nb, Sn, Zn, Hg, Cr, Fe, Sb, W, Mo, and Cu.

[0047] The Ru content of the protective film 3 is 50 atomic % or more and less than 100 atomic %, preferably 80 atomic % or more and less than 100 atomic %, and more preferably 95 atomic % or more and less than 100 atomic %. The Rh content is 10 atomic % or more and less than 70 atomic %, preferably 20 atomic % or more and less than 60 atomic %, and more preferably 30 atomic % or more and less than 50 atomic %. In this case, the protective film 3 can be provided with sufficient reflectivity for EUV light, mask cleaning resistance, an etching stopper function when the absorber film 4 is etched, and a function of preventing deterioration of the multilayer reflective film 2 over time.

[0048] The protective film 3 may also have a laminated structure of two or more layers.

[0049] Furthermore, in the multilayer reflective film coated substrate 90 of this embodiment, an underlayer may be formed between the substrate 10 and the multilayer reflective film 2. The underlayer can be formed for the purposes of improving the smoothness of the main surface of the substrate 10, reducing defects, enhancing the reflectivity of the multilayer reflective film 2, and correcting stress in the multilayer reflective film 2.

[0050] <<Back Surface Conductive Film>> The multilayer reflective film-coated substrate 90 of this embodiment may have a back surface conductive film 5 for use in an electrostatic chuck. The back surface conductive film 5 may be formed on the second main surface (back surface) of the substrate 1 (the surface opposite to the surface on which the multilayer reflective film 2 is formed, and on the intermediate layer if an intermediate layer such as a hydrogen penetration suppression film is formed on the substrate 1). The sheet resistance required for the back surface conductive film 5 for use in an electrostatic chuck is typically 100 Ω / □ (Ω / square) or less. The back surface conductive film 5 may be formed, for example, by magnetron sputtering or ion beam sputtering using a target made of a metal such as chromium or tantalum, or an alloy thereof. The chromium (Cr)-containing material of the back surface conductive film 5 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 tantalum (Ta)-containing material of the backside conductive film 5 is preferably Ta (tantalum), a Ta-containing alloy, 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. The thickness of the backside conductive film 5 is not particularly limited as long as it satisfies the function required for an electrostatic chuck, but is typically 10 nm to 200 nm.

[0051] The back surface conductive film 5 also functions to adjust the stress on the second main surface side of the reflective mask blank 100. That is, the back surface conductive film 5 is adjusted to achieve a balance with the stress from the various films formed on the first main surface side, so that a flat reflective mask blank 100 can be obtained.

[0052] It should be noted that the multilayer reflective film coated substrate 90 does not necessarily need to include the rear surface conductive film 5. For example, the rear surface conductive film 5 can be formed as needed on a reflective mask blank 100 on which an absorber film 4 described below has been formed.

[0053] <<Marks>> The marks 20 used in this embodiment include AMs (alignment marks) or FMs (fiducial marks) as reference marks in DM (defect mitigation) technology. In this embodiment, the marks 20 refer to minute concave or convex portions formed on the surface of a reflective mask 200 used in photolithography. The marks 20 can also be formed on a reflective mask blank 100 used to manufacture the reflective mask 200. The marks 20 on the reflective mask blank 100 can be formed by transferring marks 20 formed on a multilayer reflective film-coated substrate 90. A reflective mask 200 having a predetermined mark 20 can be obtained by using a reflective mask blank 100 having the mark 20.

[0054] In the following description, the mark 20 formed on the multilayer reflective film coated substrate 90 will be described as an example.

[0055] The mark 20 formed on the multilayer reflective film coated substrate 90 of this embodiment can be a reference mark 20. The reference mark 20 can also be used as an alignment mark (AM). The AM is a mark that can be used as a reference for defect coordinates when defects on the multilayer reflective film 2 are inspected using a defect inspection device. Therefore, the AM must have a high enough contrast to be detectable by the defect inspection device. Examples of defect inspection devices include the "MAGICSM7360" mask substrate / blank defect inspection device for EUV exposure manufactured by Lasertec Corporation, which has an inspection light source wavelength of 266 nm, the "Teron600 series" EUV mask / blank defect inspection device (e.g., "Teron610") manufactured by KLA-Tencor, which has an inspection light source wavelength of 193 nm, and an ABI (actinic blank inspection) device, which has an inspection light source wavelength of 13.5 nm, the same as the exposure light source wavelength.

[0056] When an AM is formed on the multilayer reflective film 2, an FM can be formed on the absorber film 4 on the multilayer reflective film 2. The AM transferred to the absorber film 4 must be detectable by a defect inspection device and a coordinate measuring device. The FM must be detectable by a coordinate measuring device and an electron beam lithography device. By managing the relative coordinates between the AM and FM, it is possible to manage defect coordinates with high precision. It is also possible to remove a portion of the absorber film 4 on the AM so that the AM is exposed. As the coordinate measuring device, the coordinate measuring device "LMS-IPRO4" manufactured by KLA-Tencor, which performs coordinate measurement using a laser with a wavelength of 365 nm, or the coordinate measuring device "PROVE" manufactured by Carl Zeiss, which performs coordinate measurement using a laser with a wavelength of 193 nm, can be used.

[0057] In the following description, an example will be given in which the mark 20 is used as a reference mark 20 on a multilayer reflective film coated substrate 90. The mark 20 can be used as an FM (fiducial mark). In this case, the FM can also function as the AM described above. In addition, an example will be given in which the mark 20 is formed on the protective film 3 of the multilayer reflective film coated substrate 90.

[0058] 3 is a plan view of a multilayer reflective film-coated substrate 90 according to an embodiment of the present invention. As shown in FIG. 3, marks 20 used as references for defect coordinates are formed near the four corners of the substantially rectangular multilayer reflective film-coated substrate 90.

[0059] 3, the region inside the dashed line A (a 132 mm×132 mm region) is a pattern formation region where the absorber pattern 4a (see FIG. 11E) is formed when the reflective mask 200 is manufactured. The region outside the dashed line A is a region where the absorber pattern 4a is not formed when the reflective mask 200 is manufactured. The marks 20 are preferably formed in the regions outside the dashed line A where the absorber pattern 4a is not formed, particularly at the four corners of the substrate 90.

[0060] In the multilayer reflective film-coated substrate 90 of this embodiment, when the cross section of the multilayer reflective film-coated substrate 90 (a cross section perpendicular to the main surface of the multilayer reflective film-coated substrate 90) is viewed, the mark 20 is formed in a concave or convex shape on the surface of the protective film 3. The term "concave" as used herein means that when the cross section of the multilayer reflective film-coated substrate 90 is viewed, the mark 20 is formed so as to be recessed, for example, in a stepped or curved shape, downward relative to the protective film 3. The term "convex" as used herein means that when the cross section of the multilayer reflective film-coated substrate 90 is viewed, the mark 20 is formed so as to be raised, for example, in a stepped or curved shape, upward relative to the protective film 3.

[0061] A single mark 20 can be recognized as a linear groove or ridge (line), or as an area (section or dot) enclosed by the edge of the groove or ridge. The edge of the groove or ridge has an inclination angle, which causes an intensity difference in the read signal during defect inspection with a defect inspection device relative to the surrounding film-forming surface (protective film 3 in this embodiment). By detecting this intensity difference in the read signal (contrast relative to the inspection light of the defect inspection device) and performing image processing, the shape pattern and coordinate position of the mark 20 can be recognized. The contrast relative to the inspection light of the defect inspection device is preferably 0.05 or more, more preferably 0.1 or more, and even more preferably 0.2 or more. The contrast varies depending on the shape of the edge of the mark 20, the depth of the mark 20, and / or the surface roughness of the mark 20, etc. Furthermore, based on the recognized pattern and position of the mark 20, a reference coordinate (reference point) in the defect coordinate system can be measured.

[0062] Furthermore, in the multilayer reflective film-coated substrate 90 of this embodiment, a plurality of reference points extracted from one or more marks 20 exist within a 460 μm×460 μm area indicated by the dashed line B in FIG. 3 . This 460 μm×460 μm area corresponds to the field of view of a defect inspection device. This 460 μm×460 μm area is selected at an arbitrary position outside the pattern formation area. A method for extracting reference points at defect coordinates based on the shape patterns of the one or more marks 20 described above will be described later.

[0063] The shape pattern of the mark 20 used in this embodiment will be described. The outline of the mark 20 shown in the drawings referred to in this specification is simplified to facilitate understanding of the shape of the mark 20. The outline of the mark 20 depicted in these drawings specifically corresponds to the ridgeline (i.e., the line connecting the centers of the inclined surfaces of the edge portions) along the peak at which the contrast of the read signal is maximized. The dashed lines in Figures 4 and 5 illustrate an area of ​​460 μm × 460 μm (corresponding to area B shown in Figure 3).

[0064] In one embodiment, the mark 20 may be a cross pattern 210 as exemplified in Fig. 4. The cross pattern 210 has a shape in which a vertical line portion 211 extending in the Y-axis direction intersects with a horizontal line portion 212 extending in the X-axis direction. The positions at which the vertical line portion 211 and the horizontal line portion 212 intersect may or may not be the centers of each other.

[0065] In this specification, the "center" of the pattern of the mark 20 may also refer to the geometric center of the shape of the mark 20. The geometric center of the shape is understood as the center of gravity in a two-dimensional plane.

[0066] From the mark 20 of the cross pattern 210, the point where the vertical line portion 211 and the horizontal bar portion 212 intersect can be extracted as the reference point RPx. That is, as shown by the dashed dotted line in Fig. 4, the intersection point between the center of the width Wv of the vertical line portion 211 (center in the X direction) and the center of the width Wh of the horizontal bar portion 212 (center in the Y direction) can be extracted as the reference point RPx. RPx: Point where the vertical line portion 211 and the horizontal bar portion 212 intersect

[0067] For example, in the embodiment of FIG. 4, four reference points RPx, RPx, RPx, RPx can be extracted from the four marks 20.

[0068] In this embodiment, the length Lv of the vertical line portion 211 is preferably 1.5 μm to 2000 μm, and more preferably 100 μm to 1000 μm. The width Wv of the vertical line portion 211 is preferably 0.5 μm to 10 μm, more preferably 0.7 μm to 5.0 μm, and even more preferably 1.0 μm to 3.0 μm. The length Lh of the horizontal line portion 212 is preferably 1.5 μm to 2000 μm, and more preferably 100 μm to 1000 μm. The width Wh of the horizontal line portion 212 is preferably 0.5 μm to 10 μm, more preferably 0.7 μm to 5.0 μm, and even more preferably 1.0 μm to 3.0 μm.

[0069] In another embodiment, the mark 20 may be a composite pattern 220 of multiple crosses, as illustrated in Fig. 5A. That is, the composite pattern 220 of crosses is a mark pattern having two or more intersections. The composite pattern 220 illustrated in Fig. 5A is a pattern obtained by combining three crosses, and has a shape in which one horizontal line portion 222 intersects with three vertical line portions 221.

[0070] For example, in the embodiment of Fig. 5A, three reference points RPx, RPx, and RPx can be extracted from one mark 20. RPx: a point where the vertical line portion 221 and the horizontal line portion 222 intersect.

[0071] In this embodiment, the preferred ranges for the length and width of the vertical line portion 221 are the same as the length Lv and width Wv of the vertical line portion 211 described above. The length Lh of the horizontal line portion 222 is preferably 1.5 μm to 2000 μm, and more preferably 100 μm to 1000 μm. The preferred range for the width of the horizontal line portion 222 is the same as the width Wh of the horizontal line portion 212 described above.

[0072] Furthermore, the cross-shaped composite pattern 220 is not limited to this form, and the number of intersecting line segments may be any number. Although not shown, the cross-shaped composite pattern 220 may have a shape in which a plurality of vertical line segments 221 intersect with a plurality of horizontal line segments 222. For example, in the case of five vertical line segments 221 and five horizontal line segments 222, a maximum of 41 reference points can be extracted, including 25 points where the five vertical line segments 221 intersect with the five horizontal line segments 222 and 16 points formed in the area surrounded by two adjacent vertical line segments 221 and two adjacent horizontal line segments 222.

[0073] In this case, the preferred ranges for the length and width of the vertical line portion 221 are the same as the length Lv and width Wv of the vertical line portion 211 described above. The preferred ranges for the length and width of the horizontal line portion 222 are the same as the length Lh and width Wh of the horizontal line portion 212 described above. The spacing between adjacent vertical line portions 221 is preferably 1.5 μm to 50 μm, and more preferably 5.0 μm to 30 μm. The spacing between adjacent horizontal line portions 222 is preferably 1.5 μm to 50 μm, and more preferably 5.0 μm to 30 μm.

[0074] Furthermore, the composite pattern 220 of multiple crosses may have a form such as that shown in Fig. 5B. Four reference points RPx, RPx, RPf, and RPf can be extracted from one mark 20 illustrated in Fig. 5B. RPx: point where the vertical line portion 221 and the horizontal line portion 222 intersect. RPf: point where the vertical line portion 221 and the horizontal line portion 222 bend.

[0075] In still other embodiments, the mark 20 may be a circular or elliptical pattern. Even such a dot-like pattern can be used as a reference point in the defect coordinate system as long as it has a contrast of 0.1 or more.

[0076] In an embodiment in which the shape of the mark 20 is a circular pattern, its diameter Dd is preferably 0.5 μm to 10 μm, and more preferably 1.0 μm to 5.0 μm. Furthermore, in an embodiment in which the shape of the mark 20 is an elliptical pattern, its major axis Ld is preferably 0.5 μm to 10 μm, and more preferably 1.0 μm to 5.0 μm. Furthermore, its minor axis Wd is preferably 0.5 μm to 10 μm, and more preferably 1.0 μm to 5.0 μm. By using such sizes for the circular and elliptical pattern marks 20, sufficient contrast can be obtained for reading the mark 20, and sufficient measurement accuracy of the reference point can be ensured.

[0077] In yet another embodiment, the mark 20 may be a polygonal pattern 250. For example, the polygonal pattern 250 may be a triangle, a square, a pentagon, a hexagon, etc. Additionally, the polygonal pattern 250 may or may not be a regular polygon.

[0078] From the mark 20 of the polygonal pattern 250, the geometric center can be extracted as the reference point RPc.

[0079] In the embodiment where polygonal pattern 250 is a regular polygon, for example as shown in FIG. 6A, its size Dp can be defined as twice the distance Rp between the center and corner of the polygon (Dp=2×Rp).

[0080] In embodiments where polygonal pattern 250 is not a regular polygon, the size of the pattern can be defined by a length Lp and a width Wp. For example, as shown in Figure 6B, the length Lp of polygonal pattern 250 can be defined as twice the distance Rpmax from the center of the polygon to the farthest corner (Lp = 2 x Rpmax). The width Wp of polygonal pattern 250 can be defined as twice the distance Rpmin from the center of the polygon to the nearest side (Wp = 2 x Rpmin).

[0081] In an embodiment in which the polygonal pattern 250 is a regular polygon, the size Dp of the polygonal pattern 250 is preferably 0.5 μm to 10 μm, and more preferably 1.0 μm to 5.0 μm. In an embodiment in which the polygonal pattern 250 is not a regular polygon, the length Lp of the polygonal pattern 250 is preferably 0.5 μm to 10 μm, and more preferably 1.0 μm to 5.0 μm. Furthermore, the width Wp of the polygonal pattern 250 is preferably 0.5 μm to 10 μm, and more preferably 1.0 μm to 5.0 μm. By making the mark 20 of the polygonal pattern 250 such a size, sufficient contrast can be obtained for reading the mark 20, and sufficient measurement accuracy of the reference point can be ensured.

[0082] In the multilayer reflective film coated substrate 90 of this embodiment, a plurality of marks 20 may be formed within the region B (460 μm×460 μm region) shown in Fig. 3. This makes it possible to extract at least one reference point based on the positional relationship between these marks.

[0083] For example, in an embodiment in which two marks 20, 20 are formed side by side as shown in Fig. 7, at least two reference points RPc, RPc can be extracted. RPc: Center of the mark

[0084] 8, in which five marks 20, 20, ... are drawn in a single stroke, at least nine reference points can be extracted, including reference points RPc, RPc, ... at the centers of each mark and reference points RPm, RPm, ... at the midpoint between two marks. The spacing between the vertical lines of adjacent marks 20 is preferably 1.5 μm to 50 μm, and more preferably 5.0 μm to 30 μm. The spacing between the horizontal lines of adjacent marks 20 is preferably 1.5 μm to 50 μm, and more preferably 5.0 μm to 30 μm.

[0085] In the case of a pattern in which multiple marks 20 can be drawn with a single stroke, it is possible to reduce the processing time for creating the marks 20. Similarly, the fewer the number of reference marks that are formed, the more likely it is that the mark processing time will be reduced.

[0086] In the multilayer reflective film coated substrate 90 of this embodiment, at least two reference points extracted from one or more marks 20 are present in, for example, a 460 μm×460 μm area indicated by dashed line B in Fig. 3. The number of reference points extracted in any area surrounded by 460 μm×460 μm is preferably 3 to 50. Furthermore, the any area can be an area surrounded by 200 μm×200 μm, an area surrounded by 100 μm×100 μm, or an area surrounded by 50 μm×50 μm.

[0087] To further improve the accuracy of aligning defect coordinates, the number of reference points present in any one of the above regions is preferably 4 or more, and more preferably 9 or more. Furthermore, since it is better to have a larger number of reference points when the contrast is low, the number of reference points can be more than 40 when the contrast is less than 0.1, and can be more than 9 when the contrast is less than 0.2.

[0088] Furthermore, from the viewpoint of the processing time of the mark 20, the number of reference points present in the above-mentioned arbitrary region is preferably 45 or less, and more preferably 30 or less. Furthermore, when the contrast is high, the number of reference points can be reduced, so when the contrast is 0.1 or more, the number of reference points can be 40 or less, and when the contrast is 0.2 or more, the number of reference points can be 9 or less.

[0089] It should be noted that it is sufficient that a predetermined number of reference points that can be recognized by a defect inspection device are present in the above-mentioned arbitrary region of, for example, 460 μm × 460 μm, and it is not a requirement that all of the reference marks for extracting the reference points are present in their entirety in the 460 μm × 460 μm region. In other words, as long as a predetermined number of reference points are present in the arbitrary region of 460 μm × 460 μm, for example, some of the reference marks may be formed outside this region.

[0090] Furthermore, as long as a pattern such as the cross-shaped composite pattern 220 allows for extraction of multiple reference points from one mark 20, an embodiment in which one mark 20 is formed in any of the above-mentioned regions may be adopted.

[0091] Furthermore, as long as a predetermined number of reference points are present in any of the above-mentioned regions, the multiple marks 20 may be an embodiment of a combination of two or more patterns selected from the above-mentioned cross pattern 210, cross composite pattern 220, circular pattern, elliptical pattern, and polygonal pattern 250.

[0092] Furthermore, the multiple marks 20 present in the given region do not have to be the same size, but can be different sizes. At least one of the multiple marks 20 can be larger than the other marks 20 in at least one of the width, length, depth, and height. The width, length, depth, or height of at least one of the multiple marks 20 can be 2 to 10 times larger than those of the other marks 20. For example, in FIG. 4, the width Wv of the vertical line portion 211 and the width Wh of the horizontal bar portion 212 of at least one cross-shaped pattern 210 can be larger than the width Wv of the vertical line portion 211 and the width Wh of the horizontal bar portion 212 of the other cross-shaped patterns 210. For example, the diameter Dd of at least one circular pattern in FIG. 13D can be larger than the diameter Dd of the other circular patterns. This allows the marks 20 to be readable by different electron beam lithography systems, for example, single-beam and multi-beam systems.

[0093] The method for forming the mark 20 is not particularly limited. The mark 20 can be formed by, for example, a laser beam, a focused ion beam (FIB), photolithography, processing marks created by scanning with a diamond needle, or embossing by an imprinting method. The mark 20 can be formed, for example, by laser processing on the surface of the protective film 3. The type of laser is a laser with a wavelength in the ultraviolet to visible light range, and for example, a semiconductor laser with a wavelength of 405 nm can be used. The mark 20 having a predetermined cross-sectional profile can be formed by changing the laser output, scanning speed, frequency, and / or focus.

[0094] The laser used in laser processing the mark 20 may be a continuous wave or a pulse wave. When a pulse wave is used, it is possible to make the width W of the mark 20 smaller than when a continuous wave is used, even if the depth D of the mark 20 is approximately the same. Furthermore, when a pulse wave is used, it is possible to control the shape of the edge of the mark 20, for example by increasing the inclination angle of the edge, compared to when a continuous wave is used. Therefore, when a pulse wave is used, it is possible to form a mark 20 having a predetermined cross-sectional profile that has greater contrast and is easier to detect using a defect inspection device or an electron beam lithography device, compared to when a continuous wave is used.

[0095] In the embodiment of the multilayer reflective film coated substrate 90 described above, the depth of the reference mark 20 is preferably 10 to 80 nm (0.01 to 0.08 μm), and more preferably 30 to 80 nm (0.03 to 0.08 μm). By having the depth of the mark 20 within the predetermined range, a sufficiently high contrast can be obtained that can be read by a defect inspection device.

[0096] According to this embodiment, by performing defect inspection on a substrate 90 with a multilayer reflective film using a defect inspection device, the position of the defect can be obtained based on the coordinates of multiple reference points measured based on the above-mentioned mark 20, and defect information can be recorded.

[0097] The above description has been given taking the case where the mark 20 is formed on the protective film 3 of the multilayer reflective film coated substrate 90 as an example, but the same applies to the case where the mark 20 is formed on the multilayer reflective film 2 .

[0098] <Reflective Mask Blank> Next, the reflective mask blank 100 of this embodiment will be described. In the reflective mask blank 100 of this embodiment, the thin film for pattern formation preferably includes at least one selected from an absorber film 4, an etching mask film 6, and a resist film 11. When the thin film of the reflective mask blank 100 of this embodiment includes a predetermined thin film, a reflective mask 200 can be manufactured using the mask blank.

[0099] As described above, the mark 20 formed on the multilayer reflective film 2 of the multilayer reflective film-coated substrate 90 is also transferred to the thin film for pattern formation (at least one selected from the absorber film 4, the etching mask film 6, and the resist film 11) when a thin film for pattern formation is formed on the multilayer reflective film-coated substrate 90. Therefore, "the surface of the reflective mask blank has at least one concave or convex mark 20" includes not only the case where the mark 20 is formed in the thin film for pattern formation on the surface of the reflective mask blank, but also the case where a mark 20 formed in a thin film (or the substrate 1) below the thin film for pattern formation is transferred to the thin film for pattern formation.

[0100] 9 and 10 are schematic diagrams showing a cross section of a reflective mask blank 100 of this embodiment. The reflective mask blank 100 of this embodiment can be manufactured by forming an absorber film 4 that absorbs EUV light on the multilayer reflective film 2 or on the protective film 3 of the multilayer reflective film-coated substrate 90 described above.

[0101] The reflective mask blank 100 of this embodiment has a mark 20 similar to the mark 20 of the multilayer reflective film-coated substrate 90. The mark 20 of the reflective mask blank 100 of this embodiment can be formed by transferring the mark 20 formed on the multilayer reflective film-coated substrate 90 to the absorber film 4. By forming an absorber film 4 on the surface of the multilayer reflective film-coated substrate 90 having the mark 20, the mark 20 formed on the multilayer reflective film-coated substrate 90 can be transferred to the absorber film 4. Furthermore, the mark 20 of the reflective mask blank 100 of this embodiment can be formed by forming an absorber film 4 on the multilayer reflective film-coated substrate 90 on which no mark 20 has been formed, and then using a method similar to the method of forming the mark 20 on the multilayer reflective film-coated substrate 90 described above.

[0102] The absorber film 4 has the function of absorbing EUV light, which is exposure light. That is, the difference between the reflectance of the multilayer reflective film 2 for EUV light and the reflectance of the absorber film 4 for EUV light is equal to or greater than a predetermined value. For example, the reflectance of the absorber film 4 for EUV light is equal to or greater than 0.1% and equal to or less than 40%. There may be a predetermined phase difference between the light reflected by the multilayer reflective film 2 and the light reflected by the absorber film 4. In this case, the absorber film 4 in the reflective mask blank 100 is sometimes called a phase shift film.

[0103] The absorber film 4 preferably has a function of absorbing EUV light and is removable by etching or the like. The absorber film 4 is preferably etchable by dry etching using a chlorine (Cl)-based gas or a fluorine (F)-based gas. As long as the absorber film 4 has such a function, the material of the absorber film 4 is not particularly limited.

[0104] The absorber film 4 may be a single layer or may have a laminated structure. When the absorber film 4 has a laminated structure, multiple films made of the same material may be laminated, or multiple films made of different materials may be laminated. When the absorber film 4 has a laminated structure, the material or composition may change stepwise and / or continuously in the thickness direction of the film.

[0105] The material of the absorber film 4 is not particularly limited as long as it has the function of absorbing EUV light, can be processed by etching or the like (preferably can be etched 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 3. 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), an alloy containing two or more metals, or a compound thereof can be preferably used. The compound may contain oxygen (O), nitrogen (N), carbon (C), and / or boron (B) in addition to the above metal or alloy.

[0106] The thickness of the absorber film 4 is preferably 30 nm to 100 nm.

[0107] The absorber film 4 can be formed by a known method, such as magnetron sputtering or ion beam sputtering.

[0108] In the reflective mask blank 100 of this embodiment, a resist film 11 may be formed on the absorber film 4. This aspect is shown in Fig. 11A. A pattern is written and exposed on the resist film 11 using an electron beam lithography device, and then a development step is performed to form a resist pattern 11a. A pattern (absorber pattern 4a) can be formed in the absorber film 4 by dry etching the absorber film 4 using this resist pattern 11a as a mask.

[0109] As shown in FIG. 10 , the reflective mask blank 100 of this embodiment can have an etching mask film 6. When the reflective mask blank 100 of this embodiment has a resist film 11, the etching mask film 6 can be disposed between the absorber film 4 and the resist film 11. The etching mask film 6 is used as a mask when patterning the absorber film 4. The etching mask film 6 is formed of a material that has etching selectivity with respect to the absorber film 4. The material of the etching mask film 6 preferably contains a chromium compound, a tantalum compound, or a silicon compound. The chromium compound contains Cr and at least one selected from the group consisting of N, O, C, and H. The tantalum compound contains Ta and at least one selected from the group consisting of N, O, B, and H. The silicon compound contains Si and at least one selected from the group consisting of N, O, C, and H.

[0110] The reference marks 20 transferred or formed on the absorber film 4, etching mask film 6, and resist film 11 must have high enough contrast to be detectable by an electron beam lithography system. The resist film 11 above the reference marks 20 may be locally removed so that the concave or convex reference marks 20 transferred to the surface of the reflective mask blank 100 can be easily detected by an electron beam lithography system. The manner of removal is not particularly limited. Alternatively, for example, the absorber film 4, etching mask film 6, and resist film 11 above the reference marks 20 may be removed.

[0111] According to this embodiment, the coordinate system of the defect inspection device can be converted with high precision into the coordinate system of the electron beam lithography device by detecting the reference mark 20 formed on the reflective mask blank 100 with a coordinate measuring device and calculating the position of the reference point. As a result, the reflective mask blank 100 of this embodiment can manage defect coordinates with high precision.

[0112] <Reflection Mask> The reflective mask blank 100 of this embodiment can be used to manufacture the reflective mask 200 of this embodiment. The reflective mask 200 of this embodiment is a type of transfer mask. A method for manufacturing the reflective mask 200 will be described below.

[0113] 11A to 11E are schematic diagrams showing a method for manufacturing a reflective mask 200. Note that the marks 20 are omitted from the illustration of FIGS.

[0114] First, a reflective mask blank 100 is prepared, which includes a substrate 1, a multilayer reflective film 2 formed on the substrate 1, a protective film 3 formed on the multilayer reflective film 2, an absorber film 4 formed on the protective film 3, and an etching mask film 6 formed on the absorber film 4. Next, as shown in Fig. 11A, a resist film 11 is formed on the etching mask film 6. A pattern is written on the resist film 11 using an electron beam lithography device, and a developing and rinsing process is performed to form a resist pattern 11a (Fig. 11B).

[0115] When a pattern is written by the electron beam lithography system, the coordinates of the mark 20 (reference mark 20) ​​on the etching mask film 6 measured using a coordinate measuring device can be used as a reference. By using the mark 20 (reference mark 20) ​​as an FM (fiducial mark) that is a reference for the defect position, it is possible to convert from the coordinate system of the defect inspection system to the coordinate system of the coordinate measuring device. Then, the above-mentioned mark 20 (reference mark 20) ​​is detected by the electron beam lithography system. A single beam or multiple beams can be used to detect the mark 20 (reference mark 20) ​​by the electron beam lithography system.

[0116] Using the resist pattern 11a as a mask, the etching mask film 6 is dry-etched, whereby the portions of the etching mask film 6 that are not covered by the resist pattern 11a are etched, and an etching mask pattern 6a is formed (FIG. 11C).

[0117] Using the etching mask pattern 6a as a mask, the absorber film 4 is dry-etched, whereby the portions of the absorber film 4 that are not covered by the etching mask pattern 6a are etched, and absorber patterns 4a are formed (FIG. 11D).

[0118] The etching gas is, for example, Cl ２ , SiCl ４ , CHCl３ , and CCl ４ Chlorine-based gases such as these, and O ２ a mixed gas containing a chlorine-based gas and He at a predetermined ratio, a mixed gas containing a chlorine-based gas and Ar at a predetermined ratio, CF ４ , CHF ３ , C ２ F ６ , C ３ F ６ , C ４ F ６ , C ４ F ８ , C.H. ２ F ２ , C.H. ３ F, C ３ F ８ , SF ６ fluorine-based gases such as F, and fluorine-based gases and O ２ in a predetermined ratio, a mixed gas containing a fluorine-based gas and He in a predetermined ratio, a mixed gas containing a fluorine-based gas and Ar in a predetermined ratio, etc. can be used.

[0119] After the absorber pattern 4a is formed, the etching mask pattern 6a is removed by dry etching. After the etching mask pattern 6a is removed, a wet cleaning process using an acidic or alkaline aqueous solution is performed to obtain the reflective mask 200 of this embodiment (FIG. 11E).

[0120] <Method of Manufacturing Semiconductor Device> A method of manufacturing a semiconductor device according to this embodiment will be described using the reflective mask 200 according to this embodiment as an example.

[0121] The method for manufacturing a semiconductor device according to this embodiment includes a step of performing a lithography process using the above-described reflective mask 200 with an EUV exposure apparatus 50 to transfer a pattern onto a semiconductor substrate 60, which is a transfer target. Fig. 12 is a schematic diagram showing an example of the EUV exposure apparatus 50.

[0122] A transfer pattern can be formed on a semiconductor substrate 60 (transfer receiving body) 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 the semiconductor substrate 60 using the reflective mask 200, a semiconductor device can be manufactured.

[0123] A method for transferring a pattern onto a semiconductor substrate 60 with a resist by using EUV light will be described with reference to FIG.

[0124] 12 shows a schematic configuration of an EUV exposure apparatus 50, which is an apparatus for transferring a transfer pattern onto a resist film formed on a semiconductor substrate 60. The EUV exposure apparatus 50 includes an EUV light generation unit 51, an irradiation optical system 56, a reticle stage 58, a projection optical system 57, and a wafer stage 59, which are precisely arranged along the optical path axis of the EUV light. The container of the EUV exposure apparatus 50 is filled with hydrogen gas.

[0125] The EUV light generation unit 51 has a laser light source 52, a tin droplet generation unit 53, a capture unit 54, and a collector 55. When the high-power carbon dioxide laser from the laser light source 52 irradiates the tin droplets emitted from the tin droplet generation unit 53, the tin droplets are converted into plasma, and EUV light is generated. The generated EUV light is collected by the collector 55 and passes through an irradiation optical system 56 to be incident on a reflective mask 200 set on a reticle stage 58. The EUV light generation unit 51 generates EUV light with a wavelength of, for example, 13.53 nm.

[0126] The EUV light reflected by the reflective mask 200 is reduced by the projection optical system 57 to a pattern image light, typically about one-fourth the original size, and projected onto the semiconductor substrate 60 (transferred substrate). As a result, a given circuit pattern is transferred onto a resist film on the semiconductor substrate 60. A resist pattern can be formed on the semiconductor substrate 60 by developing the exposed resist film. An integrated circuit pattern can be formed on the semiconductor substrate 60 by etching the semiconductor substrate 60 using the resist pattern as a mask. A semiconductor device is manufactured through these and other necessary processes.

[0127] The method for manufacturing a semiconductor device according to this embodiment uses the reflective mask 200 according to this embodiment. In the reflective mask 200 according to this embodiment, defect coordinates are managed with high precision. Therefore, the reflective mask 200 according to this embodiment is less affected by defects and is a high-performance reflective mask 200. Therefore, by using the reflective mask 200 according to this embodiment, semiconductor devices with higher performance and quality can be manufactured with a good yield.

[0128] The present invention will be specifically explained below with reference to examples, but the present invention is not limited to these examples.

[0129] As examples and comparative examples, multilayer reflective film-coated substrates 90 were fabricated in which a multilayer reflective film 2 and a protective film 3 were formed on the first main surface of a substrate 1. Marks 20 (reference marks 20) were formed on the multilayer reflective film-coated substrates 90 of the examples and comparative examples under the conditions shown in Table 1.

[0130] The multilayer reflective film coated substrates 90 of the examples and comparative examples were fabricated as follows.

[0131] A SiO 6025 size (approximately 152 mm x 152 mm x 6.35 mm) low thermal expansion glass substrate 1 with both the first and second main surfaces polished. ２ -TiO ２ A glass substrate 1 was prepared as the substrate 1. To obtain a flat and smooth main surface, polishing was carried out through a rough polishing process, a precision polishing process, a local polishing process, and a touch polishing process.

[0132] SiO ２ -TiO ２ A back surface conductive film 5 made of a TaB film was formed by magnetron sputtering (reactive sputtering) on ​​the second main surface (back surface) of the glass substrate 1. The back surface conductive film 5 was formed to a thickness of 70 nm using a TaB target in an argon (Ar) gas atmosphere.

[0133] Next, a multilayer reflective film 2 was formed on the main surface (first main surface) of the substrate 1 opposite the side on which the back surface conductive film 5 was formed. The multilayer reflective film 2 formed on the substrate 1 was a periodic multilayer reflective film made of molybdenum (Mo) and silicon (Si) to be suitable for EUV light with a wavelength of 13.5 nm. The multilayer reflective film 2 was formed by alternately stacking Mo layers and Si layers on the substrate 1 by ion beam sputtering using a Mo target and a Si target in a krypton (Kr) gas atmosphere. First, a Si film was formed to a thickness of 4.2 nm, followed by a Mo film to a thickness of 2.8 nm. This constitutes one cycle, and 40 cycles were similarly stacked. Finally, a Si film was formed to a thickness of 4.0 nm to form the multilayer reflective film 2.

[0134] Next, a protective film 3 containing a Ru compound was formed on the multilayer reflective film 2. Specifically, using a RuNb target (Ru: 80 atomic %, Nb: 20 atomic %), the protective film 3 made of a RuNb film was formed on the multilayer reflective film 2 by DC magnetron sputtering in an Ar gas atmosphere. The thickness of the protective film 3 was 2.5 nm.

[0135] As described above, the multilayer reflective film coated substrates 90 of the example and comparative example were fabricated.

[0136] Next, a reference mark 20 was formed as a mark 20 on the protective film 3 of the multilayer reflective film coated substrate 90 of the example and the comparative example.

[0137] A fiducial mark 20 was formed by laser processing on the protective film 3 of the multilayer reflective film-coated substrate 90 of Examples 1 to 8 and the Comparative Example. Figures 13A to 13H show the shape patterns of the fiducial marks 20 of Examples 1 to 8. Figure 13I shows the shape pattern of the fiducial mark of the Comparative Example. The dashed lines in Figures 13A to 13I indicate a 460 μm × 460 μm area, which is the field of view of a defect inspection device (ABI, manufactured by Lasertec Corporation).

[0138] The processing conditions for the examples and comparative examples are shown in Table 1 and are as follows: Laser type: semiconductor laser with a wavelength of 405 nm Laser output: 10 mW to 100 mW (pulse wave) Frequency: 50 to 500 kHz Spot size: 430 nmφ

[0139] In Example 1, five marks 20 each having a cross pattern of the same size as shown in FIG. 13A were formed. In Example 2, one mark 20 each having a cross-shaped composite pattern as shown in FIG. 13B was formed. In Example 3, two marks 20 each having a cross-shaped composite pattern as shown in FIG. 13C were formed. In Example 4, six marks 20 each having a circular pattern of the same size as shown in FIG. 13D were formed. In Example 5, 25 marks 20 each having a square pattern of the same size as shown in FIG. 13E were formed. In Example 6, five square marks 20 were formed by combining lines in the X direction and lines in the Y direction as shown in FIG. 13F. In Example 7, a pattern including a cross mark 20 and three circular dot marks 20 as shown in FIG. 13G was formed. In Example 8, a pattern including a cross mark 20 and six square dot marks 20 as shown in FIG. 13H was formed. In the comparative example, a cross mark as shown in FIG. 13I was formed. The number and size of the marks in the examples and comparative examples are shown in Table 1.

[0140] Next, a defect inspection device (ABI, manufactured by Lasertec Corporation) was used to extract reference points present in an area of ​​460 μm × 460 μm from one or more marks formed on the multilayer reflective film-coated substrate 90 of the example and comparative example, and their positions were measured. Table 1 shows the number of extracted reference points. The measurement time was the same for the example and comparative example.

[0141] Furthermore, a defect inspection was carried out using this defect inspection device. In the defect inspection, the position of the defect was recorded based on the coordinates of the measured reference point.

[0142] Next, an absorber film 4 was formed on the surface (surface of the protective film 3) of the multilayer reflective film 2 of each of the examples and comparative examples on which the above-mentioned marks 20 were formed.

[0143] Specifically, the absorber film 4 made of a laminated film of TaBN (thickness 56 nm) and TaBO (thickness 14 nm) was formed by DC magnetron sputtering. The TaBN film was formed using a TaB target and Ar gas and N ２The TaBO film was formed by reactive sputtering in a mixed gas atmosphere of Ar gas and O gas. ２ The marks 20 on the multilayer reflective film-coated substrate 90 were transferred onto the absorber film 4.

[0144] Next, an etching mask film 6 was formed on the surface (surface of the absorber film 4) of the reflective mask blank 100 of the example and comparative example to which the above-mentioned mark 20 had been transferred, thereby producing a reflective mask blank 100 with an etching mask film 6.

[0145] Specifically, a CrON film was formed as the etching mask film 6 in the examples and comparative examples. The CrON film (etching mask film 6) was formed using a Cr target in a gas mixture of argon (Ar) gas at a flow rate of 20 sccm and oxygen (O ２ ) gas and nitrogen (N ２ ) gas mixture was introduced and the etching was performed by DC magnetron sputtering (reactive sputtering) at a power of 1300 W. The thickness of the etching mask film 6 was 6 nm. The marks 20 on the multilayer reflective film-coated substrate 90 were transferred to the etching mask film 6.

[0146] The reference mark 20 formed on the reflective mask blank 100 was detected by a coordinate measuring device (PROVE, manufactured by Carl Zeiss), and the position of the reference point was calculated. The evaluation results of the alignment accuracy between the ABI device and PROVE are shown in Table 1.

[0147]

[0148] From the above, it can be said that by using the multilayer reflective film coated substrate 90 and reflective mask blank 100 of the embodiment on which the specified mark 20 is formed, it is possible to manage defect coordinates with higher accuracy when the measurement time is the same.

[0149] Next, a reflective mask 200 was fabricated using the reflective mask blank 100 of the above-described example.

[0150] First, as shown in Fig. 11A, a resist film 11 was formed on the etching mask film 6 of the reflective mask blank 100 of the example. A predetermined pattern was then drawn (exposed) on this resist film 11, and the resist film 11 was further developed and rinsed to form a resist pattern 11a (Fig. 11B).

[0151] When writing a pattern using an electron beam lithography system, the coordinates of the above-mentioned mark 20 (reference mark 20) ​​on the etching mask film 6, measured using a coordinate measuring instrument (PROVE, manufactured by Carl Zeiss), were used as a reference. By using the mark 20 (reference mark 20) ​​as an FM (fiducial mark) that serves as a reference for the defect position, the defect coordinates based on the defect inspection system were converted to defect coordinates based on the coordinate measuring instrument. Thereafter, the FM on the resist film 11 was detected using the electron beam lithography system. A multi-beam system was used to detect the FM. The position of the defect was identified using the FM as a reference, and the position of the resist pattern 11a was adjusted so that the defect would not adversely affect the reflective mask 200.

[0152] Next, the etching mask film 6 was dry-etched using the resist pattern 11a as a mask to form an etching mask pattern 6a (FIG. 11C). ２ Gas and O ２ The etching mask film 6 (CrON film) was dry-etched using a mixed gas of the gas.

[0153] Next, the absorber film 4 was dry-etched using the etching mask pattern 6a as a mask to form the absorber pattern 4a (FIG. 11D). Specifically, in this example, a fluorine-based gas (CF ４ After dry etching the upper TaBO film with a chlorine-based gas (Cl ２ The underlying TaBN film was dry-etched using a gas.

[0154] Thereafter, the etching mask pattern 6a was removed by dry etching (FIG. 11E). ２ Gas and O ２The etching mask pattern 6a (CrON film) was dry-etched using a mixed gas of the CrON gas, thereby removing the etching mask pattern 6a.

[0155] In this manner, the reflective mask 200 of the example was fabricated.

[0156] In the reflective mask 200 according to the example of this embodiment, the defect coordinates are managed with high precision. Therefore, the reflective mask 200 according to the example of this embodiment is less affected by defects and can be said to be a high-performance reflective mask 200.

[0157] When the reflective mask 200 obtained in this manner is set in an exposure device and a pattern is transferred onto a semiconductor substrate on which a resist film has been formed, good pattern transfer can be performed without any defects in the transferred pattern caused by the reflective mask 200.

[0158] REFERENCE SIGNS LIST 1 substrate 2 multilayer reflective film 3 protective film 4 absorber film 4a absorber pattern 5 backside conductive film 6 etching mask film 6a etching mask pattern 11 resist film 11a resist pattern 20 mark (reference mark) 50 EUV exposure device 51 EUV light generation unit 52 laser light source 53 tin droplet generation unit 54 capture unit 55 collector 56 irradiation optical system 57 projection optical system 58 reticle stage 59 wafer stage 60 semiconductor substrate 90 substrate with multilayer reflective film 100 reflective mask blank 200 reflective mask 210 cross pattern 220 cross composite pattern 250 polygonal pattern RPc, RPm, RPf, RPx reference point

Claims

1. A multilayer reflective film-coated substrate having a substrate and a multilayer reflective film disposed on the substrate, wherein one or more marks are formed outside a transfer pattern formation area on the multilayer reflective film-coated substrate, and a plurality of reference points extracted from the one or more marks are present within any area surrounded by 460 μm x 460 μm.

2. A substrate with a multilayer reflective film according to claim 1, wherein the number of reference points extracted in any area surrounded by 460 μm×460 μm is 3 or more and 50 or less.

3. The multilayer reflective film coated substrate according to claim 1 or 2, wherein at least one reference point is extracted based on the positional relationship between two or more of said marks.

4. The multilayer reflective film coated substrate according to claim 1 or 2, wherein at least one of the marks includes a cross pattern or a composite pattern of a plurality of cross patterns.

5. The multilayer reflective film coated substrate according to claim 1 or 2, wherein at least one of the marks includes a cross pattern, and the other marks include a polygonal, circular, or elliptical pattern.

6. A reflective mask blank having a substrate, a multilayer reflective film disposed on the substrate, and a thin film for forming a transfer pattern disposed on the multilayer reflective film, wherein one or more marks are formed outside the transfer pattern formation area on the reflective mask blank, and a plurality of reference points extracted from the one or more marks are present within any area surrounded by 460 μm x 460 μm.

7. A reflective mask blank according to claim 6, wherein the number of reference points extracted in any area surrounded by 460 μm×460 μm is 3 or more and 50 or less.

8. A reflective mask blank according to claim 6 or 7, wherein at least one reference point is extracted based on the positional relationship between two or more of said marks.

9. The reflective mask blank according to claim 6 or 7, wherein at least one of the marks includes a cross pattern or a composite pattern of a plurality of cross patterns.

10. The reflective mask blank according to claim 6 or 7, wherein at least one of the marks includes a cross pattern, and the other of the marks includes a polygonal, circular, or elliptical pattern.

11. A reflective mask having a substrate, a multilayer reflective film disposed on the substrate, and a thin film on which a transfer pattern is formed on the multilayer reflective film, wherein one or more marks are formed outside the transfer pattern formation area on the reflective mask, and a plurality of reference points extracted from the one or more marks are present within any area surrounded by 460 μm x 460 μm.

12. The reflective mask according to claim 11, wherein the number of reference points extracted in any area surrounded by 460 μm×460 μm is 3 or more and 50 or less.

13. The reflective mask according to claim 11 or 12, wherein at least one of said marks comprises a cross pattern or a composite pattern of a plurality of cross patterns.

14. The reflective mask according to claim 11 or 12, wherein at least one reference point is extracted based on the positional relationship between two or more of said marks.

15. A reflective mask according to claim 11 or 12, wherein at least one of said marks comprises a cross pattern and other of said marks comprise polygonal, circular or elliptical patterns.

16. A method for manufacturing a semiconductor device, comprising the step of transferring a pattern onto a semiconductor substrate using the reflective mask according to claim 11 or 12.

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