Substrate with Reflective Film, Mask Blank, Reflective Mask, and Method of Manufacturing Semiconductor Device

Abstract

To provide a substrate with reflection film which can suppress generation of a blister on a reflection film formed on an end face of a substrate.SOLUTION: The substrate with reflection film consists of: a substrate having opposing two main surfaces and an end face connected to outer edges of the two main surfaces; and a reflection film formed at least on one of the main surfaces and a part of the end face. The reflection film on the main surface has a structure in which a low refractive index layer and a high refractive index layer are alternatively laminated. The reflection film on the end face has a single layer structure containing an element having the largest content in the low refractive index layer and an element having the largest content in the high refractive index layer.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a substrate with a reflective film used in EUV lithography, a mask blank, a reflective mask, and a method for manufacturing a semiconductor device.

Background Art

[0002] Generally, in the manufacturing process of semiconductor devices, a fine pattern is formed using a photolithography method. Further, for the formation of this fine pattern, a transfer mask called a photomask is usually used in several sheets. This transfer mask is generally a transparent glass substrate provided with a fine pattern made of a metal thin film or the like, and a photolithography method is also used in the manufacture of this transfer mask.

[0003] In recent years, in the semiconductor industry, with the high integration of semiconductor devices, there has been a need for fine patterns that exceed the transfer limit of the conventional photolithography method using ultraviolet light. In order to enable such fine pattern formation, EUV lithography, an exposure technique using extreme ultraviolet (hereinafter referred to as "EUV") light, has been regarded as promising. Here, EUV light refers to light in the wavelength band of the soft X-ray region or the vacuum ultraviolet region, specifically light having a wavelength of about 0.2 to 100 nm. As a mask used in this EUV lithography, a reflective mask has been proposed. Such a reflective mask is formed with a multilayer reflective film that reflects exposure light on a substrate, and an absorber film that absorbs exposure light is formed in a pattern on the multilayer reflective film (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In recent years, due to the increasing requirements for miniaturization in the lithography process, the problems in the lithography process have become prominent. One of them is the problem of contamination adhesion to the mirrors and masks of the exposure machine due to EUV light irradiation in the EUV lithography process.

[0006] In order to solve this problem, technologies such as making the inside of the exposure chamber into a hydrogen atmosphere such as hydrogen radicals to suppress contamination adhesion during EUV exposure, and cleaning methods for removing contamination by hydrogen plasma have begun to be used.

[0007] However, when the above technologies are applied, hydrogen penetrates into the mask film and aggregates, resulting in the so-called "blister" where the film bulges, which has become a new problem. When such a film bulges and ruptures, it causes contamination inside the exposure chamber due to dust generation. It has been found that the hydrogen that penetrates into the film is easily trapped at the interface with other films depending on the film material, and blisters are likely to occur at the interface between the two stacked films.

[0008] By the way, the reflective mask used in EUV lithography has a reflective film for reflecting exposure light (EUV light) formed on a substrate. This reflective film is a multilayer film with a structure in which a low refractive index layer and a high refractive index layer are alternately laminated, and is formed on one main surface of the substrate using, for example, a sputtering method. In this case, not only is it formed on one main surface of the substrate, but the film also wraps around the end face of the substrate and deposits. If the film deposited on this end face has a multilayer film structure similar to the film formed on the main surface, the risk of blister generation at the interface of the multilayer film increases.

[0009] Therefore, the object of the present invention is, firstly, to provide a substrate with a reflective film and a mask blank that can suppress the generation of blisters in the reflective film formed particularly on the end face of the substrate, and secondly, to provide a reflective mask that can suppress the generation of blisters in the reflective film formed particularly on the end face of the substrate by using this mask blank. It is also an object of the present invention to provide a method for manufacturing a semiconductor device using this reflective mask.

Means for Solving the Problems

[0010] In order to solve the above problems, the present inventor focused particularly on the structure of the film that adhered by wrapping around even on the end face of the substrate when forming a reflective film on the main surface of the substrate, and as a result of continuous intensive studies, completed the present invention. That is, in order to solve the above problems, the present invention has the following configuration.

[0011] (Configuration 1) A substrate with a reflective film, comprising a substrate having two opposing main surfaces and end faces connecting to the outer edges of the two main surfaces, and a reflective film formed on at least a part of one of the main surfaces and the end faces. The reflective film on the main surface has a structure in which a low refractive index layer and a high refractive index layer are alternately laminated, and the reflective film on the end face has a single-layer structure containing the element with the highest content in the low refractive index layer and the element with the highest content in the high refractive index layer. A substrate with a reflective film, characterized in that.

[0012] (Configuration 2) The ratio of the content [atomic%] of the element with the highest content in the low refractive index layer to the total content [atomic%] of the element with the highest content in the low refractive index layer and the element with the highest content in the high refractive index layer contained in the reflective film formed on the end face is less than 0.4. The substrate with a reflective film according to Configuration 1, characterized in that. (Configuration 3) The film thickness of the portion of the reflective film formed on the end face is thinner than the film thickness of the portion of the reflective film formed on the main surface. The substrate with a reflective film according to Configuration 1 or 2, characterized in that.

[0013] (Configuration 4) The element with the highest content in the low refractive index layer is molybdenum, and the element with the highest content in the high refractive index layer is silicon. The substrate with a reflective film according to any one of Configurations 1 to 3, characterized in that. (Configuration 5) The surface roughness (root mean square roughness) Rq of the reflective film formed on the end face is 1.5 nm or more. The substrate with a reflective film according to any one of Configurations 1 to 4, characterized in that.

[0014] (Configuration 6) A mask blank, comprising a substrate having two opposing main surfaces and end faces connecting to the outer edges of the two main surfaces, a reflective film formed on at least a part of one of the main surfaces and on the end faces, and a thin film for pattern formation formed on the reflective film. The reflective film on the main surface has a structure in which a low refractive index layer and a high refractive index layer are alternately laminated. The reflective film on the end face has a single-layer structure containing the element with the highest content in the low refractive index layer and the element with the highest content in the high refractive index layer. A mask blank, characterized in that.

[0015] (Configuration 7) The ratio of the content [atomic%] of the element with the highest content in the low refractive index layer contained in the reflective film formed on the end face to the total content [atomic%] of the element with the highest content in the low refractive index layer and the element with the highest content in the high refractive index layer is less than 0.4. The mask blank according to Configuration 6, characterized in that. (Configuration 8) The film thickness of the portion of the reflective film formed on the end face is thinner than the film thickness of the portion of the reflective film formed on the main surface. The mask blank according to Configuration 6 or 7, characterized in that.

[0016] (Configuration 9) The element with the highest content in the low refractive index layer is molybdenum, and the element with the highest content in the high refractive index layer is silicon. The mask blank according to any one of Configurations 6 to 8, characterized in that. (Configuration 10) The surface roughness (root mean square roughness) Rq of the reflective film formed on the end face is 1.5 nm or more, and the mask blank according to any one of Configurations 6 to 9 is characterized thereby.

[0017] (Configuration 11) A reflective mask including: a substrate having two opposing main surfaces and end faces connecting to the outer edges of the two main surfaces; a reflective film formed on at least a part of one of the main surfaces and on the end faces; and a thin film formed on the reflective film and having a transfer pattern, wherein the reflective film on the main surface has a structure in which a low refractive index layer and a high refractive index layer are alternately laminated, and the reflective film on the end face has a single-layer structure including the element having the highest content in the low refractive index layer and the element having the highest content in the high refractive index layer.

[0018] (Configuration 12) The ratio of the content [atomic%] of the element having the highest content in the low refractive index layer to the total content [atomic%] of the element having the highest content in the low refractive index layer and the element having the highest content in the high refractive index layer included in the reflective film formed on the end face is less than 0.4, and the reflective mask according to Configuration 11 is characterized thereby. (Configuration 13) The film thickness of the portion of the reflective film formed on the end face is thinner than the film thickness of the portion of the reflective film formed on the main surface, and the reflective mask according to Configuration 11 or 12 is characterized thereby.

[0019] (Configuration 14) The element having the highest content in the low refractive index layer is molybdenum, and the element having the highest content in the high refractive index layer is silicon, and the reflective mask according to any one of Configurations 11 to 13 is characterized thereby. (Configuration 15) The surface roughness (root mean square roughness) Rq of the reflective film formed on the end face is 1.5 nm or more, and the reflective mask according to any one of Configurations 11 to 14 is characterized thereby.

[0020] (Configuration 16) A method for manufacturing a semiconductor device, comprising a step of exposing and transferring a transfer pattern onto a resist film on a semiconductor substrate using a reflective mask according to any one of Configurations 11 to 15.

Effects of the Invention

[0021] According to the present invention, since the reflective film on the end face has a single-layer structure containing the element with the highest content in the low refractive index layer and the element with the highest content in the high refractive index layer, it is possible to provide a substrate with a reflective film and a mask blank that can suppress the generation of blisters in the reflective film formed particularly on the end face of the substrate.

[0022] Further, according to the present invention, it is possible to provide a reflective mask that can suppress the generation of blisters in the reflective film formed particularly on the end face of the substrate by using this mask blank. Further, according to the present invention, it is possible to provide a method for manufacturing a semiconductor device using this reflective mask.

Brief Description of the Drawings

[0023]

Figure 1

Figure 2

Figure 3

Figure 4

Modes for Carrying Out the Invention

[0024] Hereinafter, embodiments of the present invention will be described in detail. [Substrate with Reflective Film] First, the substrate with a reflective film according to the present invention will be described. FIG. 1 is a cross-sectional view showing the configuration of an embodiment of a substrate with a reflective film of the present invention. As shown in FIG. 1, a substrate 10 with a reflective film according to an embodiment of the present invention includes a substrate 1 and a reflective film 2. The substrate 1 has two opposing main surfaces 1a, 1b and end faces 1c, 1d connecting to the outer edges of the two main surfaces 1a, 1b.

[0025] Since the substrate 1 used in the present invention is entirely rectangular, it has four end faces connecting to the outer edges of the two main surfaces 1a, 1b. In the present invention, the "end face" refers to these four end faces. In the cross-sectional view of FIG. 1, of the four end faces, two end faces 1c, 1d opposing each other on the left and right of the substrate are shown, but it also has the other two end faces opposing each other in the front and back of the substrate. Therefore, with respect to the other two end faces not shown in FIG. 1, the reflective film 2 is also formed at least partially thereon. In the following description of this embodiment, for the sake of convenience of explanation, the two end faces 1c, 1d will be described, but the same applies to the other two opposing end faces not shown in FIG. 1.

[0026] The reflective film 2 is formed at least partially on one main surface 1a and on the end faces 1c, 1d.

[0027] As shown in FIG. 2, the reflective film 2a formed on the main surface 1a has a multilayer film structure in which a low refractive index layer 21 and a high refractive index layer 22 are alternately laminated. In this specification, the low refractive index and the high refractive index are based on the refractive index with respect to the wavelength of EUV light. In addition, the reflective films 2c, 2d formed on the end faces 1c, 1d have a single layer structure containing the element with the highest content in the low refractive index layer 21 and the element with the highest content in the high refractive index layer 22.

[0028] Here, the element with the highest content in the low refractive index layer 21 preferably has a content exceeding 50 atomic %, more preferably 70 atomic % or more, and even more preferably 90 atomic % or more. Similarly, the element with the highest content in the high refractive index layer 22 preferably has a content exceeding 50 atomic %, more preferably 70 atomic % or more, and even more preferably 90 atomic % or more.

[0029] On the other hand, the reflective films 2c and 2d formed on the end faces 1c and 1d may have a single-layer structure containing a material in which the constituent elements of the main component of the low refractive index layer 21 and the constituent elements of the main component of the high refractive index layer 22 are mixed.

[0030] Here, the "constituent elements of the main component" of the low refractive index layer 21 (high refractive index layer 22) refer to the constituent elements excluding the elements with a content of less than 5 atomic % in the layer of the low refractive index layer 21 (high refractive index layer 22). That is, the total content of the "constituent elements of the main component" in the low refractive index layer 21 (high refractive index layer 22) in this case is 95 atomic % or more. Therefore, even if the formed reflective film contains, for example, impurity components contained in the target material or impurity components derived from structures such as shields in the film formation chamber, such components are not the constituent elements of the main component of the low refractive index layer or the high refractive index layer.

[0031] For EUV exposure, as the substrate 1, in order to prevent pattern distortion due to heat during exposure, it preferably has a low coefficient of thermal expansion within the range of 0 ± 1.0×10 -7 / °C, more preferably within the range of 0 ± 0.3×10 -7 / °C. As a material having a low coefficient of thermal expansion within this range, for example, SiO 2 -TiO 2 -based glass, multi-component glass ceramics, etc. can be used.

[0032] When using the glass substrate as the substrate 1, the main surface on the side where the transfer pattern of the glass substrate is formed is surface-treated to have a high flatness from the viewpoint of obtaining at least pattern transfer accuracy and position accuracy. In the case of EUV exposure, in the region of 132 mm × 132 mm or 142 mm × 142 mm on the main surface on the side where the transfer pattern of the glass substrate is formed, the flatness is preferably 0.1 μm or less, particularly preferably 0.05 μm or less. Further, the main surface on the side opposite to the side where the transfer pattern is formed is the surface that is electrostatically chucked when set in the exposure apparatus, and in the region of 142 mm × 142 mm, the flatness is 1 μm or less, preferably 0.5 μm or less.

[0033] In addition, the reflective film 2 is a multilayer film in which a low refractive index layer 21 and a high refractive index layer 22 are alternately laminated. Generally, a multilayer film in which a thin film of a heavy element or its compound and a thin film of a light element or its compound are alternately laminated about 40 to 60 cycles is used. For example, as a reflective film for EUV light with a wavelength of 13 to 14 nm, a Mo / Si periodic multilayer film in which a Mo film (low refractive index layer) and a Si film (high refractive index layer) are alternately laminated for 40 cycles or more is preferably used. In addition, as multilayer reflective films used in the EUV light region, there are Ru / Si periodic multilayer films, Mo / Be periodic multilayer films, Mo compound / Si compound periodic multilayer films, Si / Nb periodic multilayer films, Si / Mo / Ru periodic multilayer films, Si / Mo / Ru / Mo periodic multilayer films, Si / Ru / Mo / Ru periodic multilayer films, and the like. The reflective film 2 may be appropriately selected in terms of material according to the exposure wavelength. The reflective film 2 can be formed, for example, by an ion beam sputtering method or an atomic layer deposition method (ALD: Atomic Layer Deposition).

[0034] In order to solve the above-described problems, the inventor of the present invention has conducted intensive studies, paying particular attention to the structure of the film that wraps around and adheres to the end face of the substrate when forming a reflective film on the main surface of the substrate. As a result, it has been found that the reflective film adhering to the end face of the substrate has no need for a reflection function with respect to exposure light, and thus there is no need to adopt a multilayer film structure like the reflective film formed on the main surface of the substrate. Furthermore, from the viewpoint of suppressing the generation of blisters, it has been found that a single-layer film having no interface in the film leads to the solution of the problem.

[0035] In the substrate 10 with a reflective film according to the embodiment described above, when the reflective film 2 is formed on the main surface of the substrate 1, the reflective film 2c (or 2d) formed by wrapping around the end face 1c (or 1d) of the substrate 1 has a single-layer structure containing the element with the highest content (for example, molybdenum) in the low refractive index layer 21 and the element with the highest content (for example, silicon) in the high refractive index layer 22. This reflective film 2c (or 2d) is formed by mixing and diffusing at least the element with the highest content in the low refractive index layer 21 and the element with the highest content in the high refractive index layer 22. Such a reflective film 2c (or 2d) becomes a single-layer film having no distinct interface. Further, the reflective film 2c (or 2d) becomes a single-layer film having no interface by mixing and diffusing the constituent element (for example, molybdenum) of the main component of the low refractive index layer 21, which is the film constituent material of the reflective film 2, and the constituent element (for example, silicon) of the main component of the high refractive index layer 22. Therefore, even when a technique for suppressing contamination adhesion by hydrogen radicals or hydrogen plasma is applied during EUV exposure using a mask blank and a reflective mask, which will be described later, and which are manufactured using the substrate 10 with a reflective film of the present embodiment, it is possible to greatly reduce the risk of blister generation.

[0036] On the other hand, as described above, the reflective film 2c (or 2d) can also be a film having a single-layer structure without an interface by mixing and diffusing the constituent elements (e.g., molybdenum) of the main component of the low refractive index layer 21, which is the film constituent material of the reflective film 2, and the constituent elements (e.g., silicon) of the main component of the high refractive index layer 22. Even when a technique for suppressing contamination adhesion by hydrogen radicals or hydrogen plasma is applied to the substrate 10 with the reflective film in this case during EUV exposure using the mask blank and the reflective mask, which will be described later, and which are manufactured using this, the risk of blister generation can be significantly reduced.

[0037] As shown in FIG. 1, the film configuration of the substrate with the reflective film according to the present invention only needs to be configured to have at least a reflective film 2 that reflects exposure light (e.g., EUV light) on the substrate 1, and may further have other films such as an underlayer, which will be described later, and a protective film formed on the reflective film 2.

[0038] In the substrate 1 according to the present embodiment shown in FIG. 1, the end faces connecting to the outer edges of the two opposing main surfaces 1a and 1b are surfaces substantially perpendicular to these two main surfaces, but the substrate end face may have a chamfered surface. That is, when the end face of the substrate has side surfaces substantially perpendicular to the two main surfaces and two chamfered surfaces connecting the side surfaces to the outer edges of the two main surfaces, and the reflective film 2 is formed on at least a part of these side surfaces and chamfered surfaces, the "reflective film on the end face" refers to the reflective film formed on at least a part of these side surfaces and chamfered surfaces.

[0039] Similarly, in the substrate 10 with a reflective film of the present embodiment, the element having the highest content in the low refractive index layer 21 included in the reflective film 2c (or 2d) formed on the end face 1c (or 1d) (the constituent element of the main component of the low refractive index layer 21. For example, molybdenum.) and the element having the highest content in the high refractive index layer 22 (the constituent element of the main component of the high refractive index layer 22. For example, silicon.), the ratio of the content [atomic%] of the element having the highest content in the low refractive index layer 21 (the constituent element of the main component of the low refractive index layer 21) to the total content [atomic%] (hereinafter referred to as the L / [L + H] ratio) is preferably less than 0.4. The reflective film 2a formed on the main surface 1a of the substrate 1 preferably has a thickness ratio of the low refractive index layer to the high refractive index layer of 4:6 from the viewpoint of reflectance (that is, the L / [L + H] ratio of the entire reflective film 2a formed on the main surface 1a is 0.4).

[0040] In contrast, the reflective film 2c (or 2d) formed on the end face 1c (or 1d) of the present embodiment is a single-layer film containing the element with the highest content in the low refractive index layer 21 and the element with the highest content in the high refractive index layer 22. Or, the reflective film 2c (or 2d) is a single-layer film in which the constituent elements of the main component of the low refractive index layer 21 and the constituent elements of the main component of the high refractive index layer 22 are mixed. Also, the element with the highest content in the low refractive index layer 21 (the constituent element of the main component of the low refractive index layer 21) is often a transition metal (for example, molybdenum). The element with the highest content in the low refractive index layer 21 (the constituent element of the main component of the low refractive index layer 21) has lower chemical resistance than the element with the highest content in the high refractive index layer 22 (the constituent element of the main component of the high refractive index layer 22) and is likely to elute from the single-layer film. From this perspective, it can be said that the L / [L + H] ratio of the reflective film 2c (or 2d) formed on the end face 1c (or 1d) is preferably smaller than the L / [L + H] ratio of the entire reflective film 2a formed on the main surface 1a. The L / [L + H] ratio of the reflective film 2c (or 2d) formed on the end face 1c (or 1d) is preferably 0.33 or less, and more preferably 0.3 or less. In particular, when the element with the highest content in the low refractive index layer 21 (the constituent element of the main component of the low refractive index layer) is a transition metal and the element with the highest content in the high refractive index layer 22 (the constituent element of the main component of the high refractive index layer) is silicon, the chemical resistance is improved when the content of the transition metal is less than the stoichiometrically stable ratio of transition metal:silicon = 1:2 for transition metal silicide-based materials.

[0041] Also, the film thickness of the portion of the reflective film 2 formed on the end face (the film thickness of the reflective film 2c (or 2d)) is preferably thinner than the film thickness of the portion of the reflective film 2 formed on the main surface (the film thickness of the reflective film 2a). If the film thickness of the portion of the reflective film 2 formed on the end face is thick, the risk of dust generation due to film peeling at the substrate end face increases. Also, the possibility of forming an interface in the film increases. The ratio of the film thickness of the reflective film 2c (or 2d) to the film thickness of the reflective film 2a is preferably 0.4 or less, and more preferably 0.3 or less.

[0042] Further, the surface roughness (root mean square roughness) Rq of the reflective film 2c (or 2d) formed on the end face 1c (or 1d) is, for example, 1.5 nm or more. Note that the surface roughness (root mean square roughness) Rq of the reflective film 2c (or 2d) is preferably 2 nm or more. On the other hand, the surface roughness (root mean square roughness) Rq of the reflective film 2c (or 2d) is preferably 3 nm or less.

[0043] As described above, according to the substrate 10 with a reflective film according to this embodiment, when the reflective film 2 is formed on the main surface of the substrate 1, the reflective film 2c (or 2d) formed by wrapping around the end face 1c (or 1d) of the substrate 1 has a single-layer structure containing the element with the highest content (for example, molybdenum) in the low refractive index layer 21 and the element with the highest content (for example, silicon) in the high refractive index layer 22. This reflective film 2c (or 2d) is a film having a single-layer structure without a distinct interface. Further, according to the substrate 10 with a reflective film according to this embodiment, when the reflective film 2 is formed on the main surface of the substrate 1, the reflective film 2c (or 2d) formed by wrapping around the end face 1c (or 1d) of the substrate 1 is a film having a single-layer structure in which the constituent elements (for example, molybdenum) of the main component of the low refractive index layer, which is the film constituent material of the reflective film 2, and the constituent elements (for example, silicon) of the main component of the high refractive index layer are mixed and diffused and do not have an interface. Therefore, even when a technique for suppressing contamination adhesion by hydrogen radicals or hydrogen plasma is applied during EUV exposure using a reflective mask manufactured using the substrate 10 with a reflective film of this embodiment, the risk of blister generation can be significantly reduced.

[0044] [Mask blank] Next, the mask blank according to the present invention will be described. The mask blank according to the present invention comprises a substrate having two opposing main surfaces and end faces connecting to the outer edges of the two main surfaces, a reflective film formed on at least a part of one of the main surfaces and on the end faces, and a thin film for pattern formation formed on the reflective film. The reflective film on the main surface has a structure in which a low refractive index layer and a high refractive index layer are alternately laminated. The reflective film on the end face has a single-layer structure containing the element with the highest content in the low refractive index layer and the element with the highest content in the high refractive index layer. It is a mask blank characterized by this.

[0045] Alternatively, the mask blank according to the present invention comprises a substrate, a reflective film, and a thin film for pattern formation. The substrate has two opposing main surfaces and end faces connecting to the outer edges of the two main surfaces. The reflective film is formed on at least a part of one of the main surfaces and on the end faces. The reflective film on the main surface has a structure in which a low refractive index layer and a high refractive index layer are alternately laminated. The reflective film on the end face has a single-layer structure containing a material in which the constituent elements of the main component of the low refractive index layer and the constituent elements of the main component of the high refractive index layer are mixed. The thin film for pattern formation is formed on the reflective film. It is a mask blank characterized by this.

[0046] The film configuration of the mask blank according to the present invention may be a configuration having at least a reflective film that reflects exposure light (for example, EUV light) and a thin film for pattern formation on the substrate, and may also be a configuration having other films such as an underlayer described later, a protective film formed on the reflective film, and an etching mask film formed on the thin film for pattern formation. The thin film for pattern formation may be an absorber film that absorbs EUV light. Further, the thin film for pattern formation may be a phase shift film having a function of transmitting EUV light at a predetermined transmittance and a function of generating a predetermined phase difference between the EUV light transmitted through the thin film, reflected at the interface with the reflective film, and emitted again from the thin film, and the EUV light directly reflected by the reflective film passing through the vacuum.

[0047] Also in the mask blank according to the present invention, the reflective film is formed on at least a part of one of the main surfaces and the end surfaces. The reflective film on the main surface has a structure in which a low refractive index layer and a high refractive index layer are alternately laminated. The reflective film on the end surface has a single-layer structure containing a material in which constituent elements of the main component of the low refractive index layer and constituent elements of the main component of the high refractive index layer are mixed. Such features have been described in detail in the above-mentioned "substrate with reflective film", so duplicate explanations are omitted here.

[0048] Also, regarding the mask blank according to the present invention, the following matters are the same as those in the case of the above-mentioned "substrate with reflective film", so the explanations are omitted here. (1) The ratio (L / [L + H] ratio) of the content [atomic%] of the element with the highest content in the low refractive index layer (constituent element of the main component of the low refractive index layer) contained in the reflective film formed on the end surface to the total content [atomic%] of the element with the highest content in the high refractive index layer (constituent element of the main component of the high refractive index layer) is less than 0.4. (2) The film thickness of the portion of the reflective film formed on the end surface is thinner than the film thickness of the portion formed on the main surface of the reflective film. (3) The low refractive index layer is made of a material containing, for example, molybdenum, and the high refractive index layer is made of a material containing, for example, silicon. (4) The surface roughness (root mean square roughness) Rq of the reflective film formed on the end surface is 1.5 nm or more. (5) Other matters related to (1) to (4).

[0049] FIG. 3 is a cross-sectional view showing the configuration of an embodiment of the mask blank of the present invention. In FIG. 3, the same reference numerals are given to the portions equivalent to those in FIG. 1 described above. In the mask blank 20 according to an embodiment of the present invention shown in FIG. 3, a substrate 1, a reflective film 2 formed on the substrate 1 and reflecting, for example, EUV light, a protective film 3, and a thin film 4 for pattern formation are provided. In the present embodiment, the case where the thin film 4 for pattern formation is an absorber film that absorbs exposure light (for example, EUV light) will be described.

[0050] Details of the substrate 1 and the reflective film 2 are as described above.

[0051] In the case of EUV exposure, as the substrate 1, as described above, a glass substrate having a low coefficient of thermal expansion such as SiO 2 -TiO 2 -based glass is preferably used. However, it may be difficult for such a glass substrate to achieve a high smoothness of, for example, 0.1 nm or less in terms of surface roughness (root mean square roughness) by precision polishing. Therefore, for the purpose of reducing the surface roughness of the glass substrate or reducing defects on the surface of the glass substrate, it is preferable to form an underlayer (not shown) on the surface of the glass substrate (the substrate 1). As a material for such an underlayer, it is not necessary to have translucency to exposure light, and a material that can obtain high smoothness when the surface of the underlayer is precision polished and has good defect quality is preferably selected. For example, Si or a silicon compound containing Si (for example, SiO 2 , SiON, etc.) is preferably used because high smoothness can be obtained when precision polished and the defect quality is good. As the material of the underlayer, Si is particularly preferable.

[0052] The surface of such an underlayer is preferably a surface that has been precisely polished to achieve the smoothness required for a substrate for a mask blank. The surface of the underlayer is desirably precisely polished so that the root mean square roughness (Rq) is 0.15 nm or less, particularly preferably 0.1 nm or less. Further, considering the influence on the surface of the reflective film 2 formed on the underlayer, in relation to the maximum surface roughness (Rmax), it is preferable that Rmax / Rq is 2 to 10, and particularly preferably, it is precisely polished so as to be 2 to 8. The film thickness of the underlayer is preferably in the range of, for example, 75 nm to 300 nm.

[0053] Normally, for the purpose of protecting the reflective film 2 when patterning or pattern-correcting the thin film 4 for pattern formation, it is desirable to provide a protective film 3 between the reflective film 2 and the thin film 4 for pattern formation as in the present embodiment.

[0054] The protective film 3 is formed on the reflective film 2 in order to protect the reflective film 2 from dry etching and cleaning in the manufacturing process of the reflective mask 30. Also, the reflective film 2 can be protected by the protective film 3 during the correction of black defects (EB defect correction) of the transferred pattern using an electron beam (EB). The protective film 3 can have a laminated structure of three or more layers. For example, the lowermost layer and the uppermost layer of the protective film 3 can be layers made of a substance containing Ru, and a structure can be adopted in which a metal other than Ru or an alloy of a metal other than Ru is interposed between the lowermost layer and the uppermost layer. The material of the protective film 3 is constituted by, for example, a material mainly containing ruthenium. As the material mainly containing ruthenium, Ru metal alone or a Ru alloy containing metals such as titanium (Ti), niobium (Nb), molybdenum (Mo), zirconium (Zr), yttrium (Y), boron (B), lanthanum (La), cobalt (Co), and / or rhenium (Re) can be used. Further, these materials of the protective film 3 can further contain nitrogen. The protective film 3 is effective when patterning the thin film 4 for pattern formation by dry etching with a Cl-based gas.

[0055] The thickness of the protective film 3 is not particularly limited as long as it can perform its function as the protective film 3. From the perspective of the reflectivity of EUV light, the thickness of the protective film 3 is preferably from 1.0 nm to 8.0 nm, more preferably from 1.5 nm to 6.0 nm.

[0056] The protective film 3 may be provided on the reflective film 2c (or 2d) formed on the end face 1c (or 1d), but it is not essential to provide it. The reflective film 2c (or 2d) on the end face 1c (or 1d) often does not have the thin film 4 for pattern formation provided thereon and is less affected by dry etching or EB defect correction. Further, the reflective film 2c (or 2d) is a single-layer film containing the element with the highest content in the low refractive index layer and the element with the highest content in the high refractive index layer, or a single-layer film formed of a material in which the constituent elements of the main component of the low refractive index layer and the constituent elements of the main component of the high refractive index layer are mixed, and has high resistance to these, including chemical resistance. For these reasons, the necessity of providing the protective film 3 on the reflective film 2c (or 2d) is low. Note that the surface layer of the reflective film 2c (or 2d) (for example, a region within 5 nm from the surface) may have a composition in which the constituent elements of the protective film 3 are also mixed.

[0057] Also, in the mask blank 20 of the present embodiment, the thin film 4 for pattern formation may be a single-layer film or a multilayer film composed of a plurality of films. In the case of a single-layer film, there is a feature that the number of steps in mask blank manufacturing can be reduced and the production efficiency can be increased. In the case of a multilayer film, the optical constants and film thickness can be appropriately set so that the upper thin film becomes an antireflection film during mask pattern defect inspection using light. As a result, the inspection sensitivity during mask pattern defect inspection using light is improved. Further, when a film to which oxygen (O), nitrogen (N), etc. that improve oxidation resistance are added is used for the upper thin film, the stability over time is improved.

[0058] As the material of the thin film 4 for pattern formation, there is no particular limitation as long as it has a function of absorbing EUV light and can be processed by etching or the like (preferably, it can be etched by dry etching with a chlorine (Cl) and / or fluorine (F)-based gas). As a material having such a function, tantalum (Ta) alone or a material containing Ta can be preferably used.

[0059] Examples of the material containing Ta include a material containing Ta and B, a material containing Ta and N, a material containing Ta, B, and at least one of O and N, a material containing Ta and Si, a material containing Ta, Si, and N, a material containing Ta and Ge, a material containing Ta, Ge, and N, a material containing Ta and Pd, a material containing Ta and Ru, and a material containing Ta and Ti.

[0060] The thin film 4 for pattern formation can be formed of a material containing at least one selected from the group consisting of, for example, Ni alone, a material containing Ni, Cr alone, a material containing Cr, Ru alone, a material containing Ru, Pd alone, a material containing Pd, Mo alone, and a material containing Mo.

[0061] The thin film 4 for pattern formation can be formed by, for example, a sputtering method. The film thickness of the thin film 4 for pattern formation is preferably in the range of, for example, 25 nm to 70 nm.

[0062] Also, an etching mask film may be provided on the thin film 4 for pattern formation. By having the etching mask film, when patterning the thin film 4 for pattern formation, the resist film formed on the absorber film can be thinned, so that a fine pattern can be formed on the thin film 4 for pattern formation with high precision.

[0063] Such an etching mask film is formed of a material having etching selectivity with respect to the thin film 4 for pattern formation. When the absorber film is formed of the above tantalum-based material, the etching mask film is preferably formed of, for example, a chromium-based material. Examples of the chromium-based material include chromium (Cr) alone or chromium compounds (such as chromium oxide, chromium nitride, chromium oxynitride, and chromium carbide). The above etching mask film can be formed, for example, by a sputtering method. Further, the film thickness of the above etching mask film is preferably in the range of, for example, 5 nm to 15 nm.

[0064] The mask blank 20 according to the present embodiment as shown in FIG. 3 described above can be manufactured by sequentially forming the reflection film 2, the protective film 3, and the thin film 4 for pattern formation on the substrate 1. Further, if necessary, an underlayer (not shown) can be formed between the substrate 1 and the reflection film 2. Further, if necessary, an etching mask film (not shown) can be formed on the thin film 4 for pattern formation.

[0065] Also in the mask blank 20 according to the present embodiment described above, when the reflection film 2 is formed on the main surface of the substrate 1, the film formed on the end surface of the substrate 1 is a single-layer film in which, for example, Si and Mo, which are the film constituent materials of the reflection film 2, are mixed and diffused and have no interface. Therefore, even if a technique for suppressing contamination adhesion by hydrogen radicals or hydrogen plasma is used during EUV exposure, it is possible to greatly reduce the risk of blister generation.

[0066] [Reflective mask] The present invention also provides a reflective mask. The reflective mask according to the present invention is a reflective mask characterized in that a transfer pattern is provided in the thin film for pattern formation of the mask blank having the above-described configuration. FIG. 4 is a cross-sectional configuration diagram of a reflective mask manufactured using the mask blank of the present invention. In FIG. 4, the same reference numerals are given to the portions equivalent to those in FIG. 1 or FIG. 3 described above. FIG. 4 shows a reflective mask 30 including a transferred pattern 4a obtained by patterning a thin film 4 for pattern formation in the mask blank 20 shown in FIG. 3 described above.

[0067] For example, the method of patterning the thin film 4 for pattern formation in the mask blank 20 described above is most preferably a photolithography method. That is, in order to obtain the reflective mask of the present invention, a step of forming a resist film on the surface of the mask blank 20 using the mask blank 20 described above, a step of forming a resist pattern by electron beam lithography and development on this resist film, and using the formed resist pattern as a mask and patterning the thin film 4 for pattern formation by dry etching are preferably included in the manufacturing method.

[0068] Also in the reflective mask 30 according to the embodiment described above, as described above, when the reflective film 2 is formed on the main surface of the substrate 1, the film formed on the end surface of the substrate 1 is a single-layer film in which, for example, Si and Mo, which are the film constituent materials of the reflective film 2, are mixed and diffused and have no interface. Therefore, even if a technique for suppressing contamination adhesion by hydrogen radicals or hydrogen plasma is applied during EUV exposure using this reflective mask 30, it is possible to suppress the generation of blisters and greatly reduce the risk of blister generation.

[0069] [Method for manufacturing a semiconductor device] The present invention also provides a method for manufacturing a semiconductor device, which includes a step of exposing and transferring a transferred pattern onto a resist film on a semiconductor substrate using the reflective mask described above. By using the reflective mask according to the present invention, even if a technique for suppressing contamination adhesion by hydrogen radicals or hydrogen plasma is used during EUV exposure, it is possible to greatly reduce the risk of blister generation. Therefore, according to the present invention, good pattern transfer can be performed, and a high-quality semiconductor device in which a highly accurate device pattern is formed can be manufactured. [Examples]

[0070] Hereinafter, embodiments of the present invention will be described more specifically with reference to examples. (Example 1) Using a double-sided polishing apparatus, polishing was performed stepwise with cerium oxide abrasive grains or colloidal silica abrasive grains, and the surface of the substrate was surface-treated with a low-concentration hydrofluoric acid to obtain SiO 2 -TiO 2 A system glass substrate (size: about 152.4 mm × about 152.4 mm, thickness: about 6.35 mm) was prepared. The surface roughness of the obtained glass substrate 1 was 0.20 nm in terms of root mean square roughness (Rq). The surface roughness was measured with an atomic force microscope (AFM), and the measurement area was 1 μm × 1 μm.

[0071] Next, on the main surface 1b of this glass substrate 1 (the main surface facing the main surface 1a on the side where the reflective film 2 is provided), a conductive back film (not shown) having a laminated structure of a lower layer made of CrON and an upper layer made of CrN was formed. The lower layer (CrON layer) was formed to a thickness of 15 nm by reactive sputtering (DC magnetron sputtering) in a mixed gas atmosphere of Ar gas, N 2 gas and O 2 gas. The upper layer (CrN layer) was formed to a thickness of 180 nm by reactive sputtering (DC magnetron sputtering) in a mixed gas atmosphere of Ar gas and N 2 gas. When the composition (atomic %) of the CrN layer was measured by X-ray photoelectron spectroscopy (XPS), the atomic ratio was 91 atomic % of chromium (Cr) and 9 atomic % of nitrogen (N).

[0072] Next, on the main surface 1a of this glass substrate 1, using an ion beam sputtering apparatus, a Si film (film thickness: 2.8 nm) of a high refractive index layer and a Mo film (film thickness: 4.2 nm) of a low refractive index layer were stacked 40 cycles with one cycle as a reflection film 2 (total film thickness 280 nm) composed of a multilayer film. Specifically, the conductive back surface film of the glass substrate 1 was fixed to the stage of the ion beam sputtering apparatus with an electrostatic chuck, and sputtering particles (Si particles and Mo particles) were incident from an oblique direction onto the main surface 1a of the glass substrate, and deposited on the main surface 1a and the end faces 1c and 1d respectively, thereby forming the reflection film 2. During this film formation, the end faces 1c and 1d of the glass substrate were not masked with a shield or the like. Through the above steps, the substrate with a reflection film of Example 1 was obtained.

[0073] In addition, the above reflection film was formed not only on the main surface 1a of the glass substrate but also so as to wrap around the end faces of the glass substrate (four end faces including 1c and 1d). The reflection film on the end face of this glass substrate was analyzed using a transmission electron microscope (TEM). As a result, it was confirmed that the film thickness of the portion formed on the end face of the reflection film was thinner than the film thickness of the portion formed on the main surface of the reflection film (about 40 nm). It was also confirmed that the reflection film on the end face of the glass substrate has a single-layer structure instead of a multilayer structure. Therefore, the reflection film on the end face of the glass substrate does not have a reflection function for the exposure light. Further, as a result of analyzing the composition of the reflection film on the end face of the glass substrate with an energy dispersive transmission electron microscope (TEM-EDX), it was confirmed that the above Si and Mo were contained. That is, when the above reflection film was formed on the main surface of the glass substrate, the film that adhered by wrapping around the end face of the glass substrate was a single-layer film in which Si and Mo, which are the film constituent materials of the above reflection film, were mixed and diffused and had no interface.

[0074] In addition, the ratio obtained by dividing the content [atomic %] of Mo, which is a constituent element of the low refractive index layer contained in the reflective film formed on the end face of the substrate, by the total content [atomic %] of Mo, which is a constituent element of the low refractive index layer, and Si, which is a constituent element of the high refractive index layer, was 0.25. Further, the surface roughness (root mean square roughness) Rq of the reflective film formed on the end face was 2 nm or more.

[0075] Next, in exactly the same manner as above, a conductive back film was formed on the main surface 1b of the glass substrate 1, and a reflective film composed of a multilayer film was formed by laminating a Si film and a Mo film 40 times on the main surface 1a to obtain a substrate with a reflective film. Next, using a DC magnetron sputtering apparatus, a protective film made of Ru (film thickness: 2.5 nm), and an absorber film composed of a laminated film of a TaN film (film thickness: 48 nm, composition Ta:N = 70 atomic %: 30 atomic %) and a TaO film (film thickness: 11 nm, composition Ta:O = 35 atomic %: 65 atomic %) were formed on the reflective film of this substrate with a reflective film. Each composition was measured by X-ray photoelectron spectroscopy (XPS). As described above, a mask blank (reflective mask blank) was fabricated.

[0076] Next, a reflective mask was fabricated using this mask blank. First, an electron beam lithography positive resist film was formed as a resist film on the surface of the absorber film of the above mask blank to a film thickness of 80 nm. The resist film was formed by spin coating using a spinner (rotary coating apparatus).

[0077] Next, after a predetermined mask pattern was drawn on the above resist film using an electron beam lithography machine, development was performed to form a resist pattern.

[0078] Next, using this resist pattern as a mask, the TaO film of the above absorber film was etched away with a fluorine-based gas (CF 4 gas), and the TaN film was etched away with a chlorine-based gas (Cl 2 gas) to form an absorber film pattern. Furthermore, the resist pattern remaining on the absorber film pattern was removed with hot sulfuric acid to obtain a reflective mask for EUV lithography in Example 1. When observing the reflective films 2c and 2d on the end faces 1c and 1d of the reflective mask of Example 1, it was confirmed that there was no noticeable film reduction.

[0079] When the reflective mask obtained as described above is set in an EUV exposure apparatus and pattern transfer is performed onto a semiconductor substrate on which a resist film is formed, as described above, in order to suppress contamination adhesion to the mirrors and masks of the exposure machine during EUV exposure, for example, it is desirable to make the inside of the exposure chamber into a hydrogen atmosphere such as hydrogen radicals. In the case of the reflective mask according to this example, as described above, when the reflective film is formed on the main surface of the glass substrate, the film formed on the end face of the glass substrate is not a multilayer film structure, but a single-layer film structure in which Si and Mo, which are the film constituent materials of the reflective film, are mixed and diffused and have no interface. Therefore, even if a technique for suppressing contamination adhesion by hydrogen radicals or hydrogen plasma is used during EUV exposure, the risk of blister generation can be greatly reduced. Therefore, according to the present invention, good pattern transfer can be performed.

[0080] (Comparative Example) Similar to Example 1, a double-sided polishing apparatus was used, and stepwise polishing was performed with cerium oxide abrasive grains and colloidal silica abrasive grains, and the surface of the substrate was surface-treated with a low-concentration hydrofluoric acid to obtain a SiO 2 -TiO 2 -based glass substrate (size: approximately 152.4 mm × approximately 152.4 mm, thickness: approximately 6.35 mm) was prepared. The surface roughness of the obtained glass substrate 1 was 0.25 nm in root mean square roughness (Rq). The surface roughness was measured with an atomic force microscope (AFM), and the measurement area was 1 μm × 1 μm.

[0081] Next, in the same procedure as in Example 1, a conductive back film (not shown) having a laminated structure of a lower layer made of CrON and an upper layer made of CrN was formed on the main surface 1b of the glass substrate 1.

[0082] Next, on the main surface 1a of this glass substrate 1, using an ALD (Atomic Layer Deposition) apparatus (a film-forming apparatus using atomic layer deposition method), a Si film (film thickness: 2.8 nm) of a high refractive index layer and a Mo film (film thickness: 4.2 nm) of a low refractive index layer were stacked 40 cycles as one cycle to form a reflective film (total film thickness 280 nm) composed of a multilayer film. By respectively irradiating Si particles and Mo particles from an oblique direction onto the main surface 1a of the glass substrate and depositing them on the main surface 1a and end faces 1c, 1d, a reflective film 2 was formed. Note that during this film formation, the end faces 1c, 1d of the glass substrate were not masked with a shield or the like. Through the above steps, a substrate with a reflective film of the comparative example was obtained.

[0083] Note that the reflective film was formed not only on the main surface of the glass substrate but also so as to wrap around the end faces of the glass substrate. The structure of the reflective film on the end face of this glass substrate was analyzed using a transmission electron microscope (TEM). As a result, it was confirmed that the reflective film on the end face of the glass substrate had a multilayer film structure in which Si films and Mo films similar to those formed on the main surface were alternately stacked. That is, when the reflective film was formed on the main surface of the glass substrate, the film that wrapped around and adhered to the end face of the glass substrate was a film with a multilayer film structure having an interface.

[0084] Next, in exactly the same manner as above, a conductive back film was formed on the main surface 1b of the glass substrate 1, and a reflective film composed of a multilayer film with Si films and Mo films stacked 40 cycles was formed on the main surface 1a to obtain a substrate with a reflective film. Next, in the same manner as in Example 1 described above, a protective film made of Ru and an absorber film composed of a stacked film of a TaN film and a TaO film were formed on the reflective film of this substrate with a reflective film to fabricate a mask blank (reflective mask blank) of the comparative example.

[0085] Next, using this mask blank, a reflective mask for EUV lithography of the comparative example was fabricated in the same manner as in Example 1 described above.

[0086] When the reflective mask obtained as described above is set in an EUV exposure apparatus and pattern transfer is performed onto a semiconductor substrate on which a resist film is formed, it is desirable to apply a technique for suppressing contamination adhesion by hydrogen radicals or hydrogen plasma during EUV exposure. However, in the case of the reflective mask according to this comparative example, as described above, the film formed on the end face of the glass substrate has a multilayer film structure and has an interface between each layer. Therefore, when a technique for suppressing contamination adhesion by hydrogen radicals or hydrogen plasma is used during EUV exposure, the risk of blister generation in the film on the substrate end face becomes high, which may cause contamination inside the exposure chamber, for example, and it becomes difficult to perform good pattern transfer.

Explanation of Signs

[0087] 1 Substrate 1a, 1b Main surface 1c, 1d End face 2 Reflective film 2a Reflective film on the main surface of the substrate 2c, 2d Reflective film on the end face of the substrate 21 Low refractive index layer 22 High refractive index layer 3 Protective film 4 Thin film for pattern formation 4a Transfer pattern 10 Substrate with reflective film 20 Mask blank 30 Reflective mask

Claims

1. A substrate with a reflective film, comprising: a substrate having two opposing main surfaces and end faces connecting to the outer edges of the two main surfaces; a reflective film formed on at least a part of one of the main surfaces and on the end faces, wherein the reflective film on the main surface has a structure in which a low refractive index layer and a high refractive index layer are alternately laminated; the reflective film on the end face has a single-layer structure containing the element with the highest content in the low refractive index layer and the element with the highest content in the high refractive index layer, a single-layer film having no interface containing the element with the highest content in the low refractive index layer and the element with the highest content in the high refractive index layer, or a single-layer film in which the element with the highest content in the low refractive index layer and the element with the highest content in the high refractive index layer are mixed or diffused; A substrate with a reflective film, characterized in that the ratio of the content [atomic%] of the element with the highest content in the low refractive index layer to the total content [atomic%] of the element with the highest content in the low refractive index layer and the element with the highest content in the high refractive index layer contained in the reflective film formed on the end face is less than 0.

4.

2. The substrate with a reflective film according to claim 1, characterized in that the L / [L + H] ratio of the content [atomic%] of the element with the highest content in the low refractive index layer to the total content [atomic%] of the element with the highest content in the low refractive index layer and the element with the highest content in the high refractive index layer contained in the reflective film formed on the end face is smaller than the L / [L + H] ratio of the entire reflective film on the main surface.

3. The substrate with a reflective film according to claim 1 or 2, characterized in that the film thickness of the portion of the reflective film formed on the end face is thinner than the film thickness of the portion of the reflective film formed on the main surface.

4. The substrate with a reflective film according to any one of claims 1 to 3, characterized in that the element with the highest content in the low refractive index layer is molybdenum, and the element with the highest content in the high refractive index layer is silicon.

5. The substrate with a reflective film according to any one of claims 1 to 4, characterized in that the surface roughness (root mean square roughness) Rq of the reflective film formed on the end face is 1.5 nm or more.

6. A mask blank, comprising: a substrate having two opposing main surfaces and end faces connecting to the outer edges of the two main surfaces; a reflective film formed on at least a part of one of the main surfaces and on the end faces; a thin film for pattern formation formed on the reflective film. The reflective film on the main surface has a structure in which a low refractive index layer and a high refractive index layer are alternately laminated. The reflective film on the end face has a single-layer structure containing the element with the highest content in the low refractive index layer and the element with the highest content in the high refractive index layer, a film having a single-layer structure without an interface containing the element with the highest content in the low refractive index layer and the element with the highest content in the high refractive index layer, or a film having a single-layer structure in which the element with the highest content in the low refractive index layer and the element with the highest content in the high refractive index layer are mixed or diffused. The mask blank is characterized in that the ratio of the content [atomic%] of the element with the highest content in the low refractive index layer to the total content [atomic%] of the element with the highest content in the low refractive index layer and the element with the highest content in the high refractive index layer contained in the reflective film formed on the end face is less than 0.

4.

7. The mask blank according to claim 6, characterized in that the L / [L + H] ratio of the content [atomic%] of the element with the highest content in the low refractive index layer to the total content [atomic%] of the element with the highest content in the low refractive index layer and the element with the highest content in the high refractive index layer contained in the reflective film formed on the end face is smaller than the L / [L + H] ratio of the entire reflective film on the main surface.

8. The mask blank according to claim 6 or 7, characterized in that the film thickness of the portion of the reflective film formed on the end face is thinner than the film thickness of the portion of the reflective film formed on the main surface.

9. The mask blank according to any one of claims 6 to 8, characterized in that the element with the highest content in the low refractive index layer is molybdenum, and the element with the highest content in the high refractive index layer is silicon.

10. The mask blank according to any one of claims 6 to 9, characterized in that the surface roughness (root mean square roughness) Rq of the reflective film formed on the end face is 1.5 nm or more.

11. A reflective mask, comprising: a substrate having two opposing main surfaces and end faces connecting to the outer edges of the two main surfaces; a reflective film formed on at least a part of one of the main surfaces and the end faces; a thin film formed on the reflective film and provided with a transfer pattern, wherein the reflective film on the main surface has a structure in which a low refractive index layer and a high refractive index layer are alternately laminated. The reflective film on the end face has a single-layer structure containing the element with the highest content in the low refractive index layer and the element with the highest content in the high refractive index layer, a film with a single-layer structure having no interface containing the element with the highest content in the low refractive index layer and the element with the highest content in the high refractive index layer, or a film with a single-layer structure in which the element with the highest content in the low refractive index layer and the element with the highest content in the high refractive index layer are mixed or diffused. The reflective mask is characterized in that the ratio of the content [atomic%] of the element with the highest content in the low refractive index layer to the total content [atomic%] of the element with the highest content in the low refractive index layer and the element with the highest content in the high refractive index layer contained in the reflective film formed on the end face is less than 0.

4.

12. The reflective mask according to claim 11, characterized in that the L / [L + H] ratio of the content [atomic%] of the element with the highest content in the low refractive index layer to the total content [atomic%] of the element with the highest content in the low refractive index layer and the element with the highest content in the high refractive index layer contained in the reflective film formed on the end face is smaller than the L / [L + H] ratio of the entire reflective film on the main surface.

13. The reflective mask according to claim 11 or 12, characterized in that the film thickness of the portion of the reflective film formed on the end face is thinner than the film thickness of the portion of the reflective film formed on the main surface.

14. The reflective mask according to any one of claims 11 to 13, characterized in that the element with the highest content in the low refractive index layer is molybdenum, and the element with the highest content in the high refractive index layer is silicon.

15. The reflective mask according to any one of claims 11 to 14, characterized in that the surface roughness (root mean square roughness) Rq of the reflective film formed on the end face is 1.5 nm or more.

16. A method for manufacturing a semiconductor device, comprising the step of exposing and transferring a transfer pattern to a resist film on a semiconductor substrate using the reflective mask according to any one of claims 11 to 15.

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