Substrate with multilayer reflective film for EUV mask blank, method for manufacturing the same, and EUV mask blank

Abstract

SOLUTION: A substrate with a multilayer reflection film for an EUV mask blank includes a substrate, and a multilayer reflection film formed on the substrate. The multilayer reflection film includes a Si / Mo laminated portion, in which Si layers and Mo layers are alternately laminated, and a protection layer containing Ru formed on the Si / Mo laminated portion and in contact with the Si / Mo laminated portion, as the uppermost layer of the multilayer reflection film. The protection layer includes the two layers of a lower layer formed in contact with the Si / Mo laminated portion, and an upper layer formed at the side remotest from the substrate. The lower layer is composed of Ru, and the upper layer is composed of a material containing Ru and at least one selected from the group consisting of metals other than Ru, and metalloids.EFFECT: This invention achieves a substrate with a multilayer reflection film for an EUV mask blank, and an EUV mask blank, which offer necessary etching resistance and high reflectance, and have reduced susceptibility to reflectance loss under heat.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an EUV mask blank serving as a material for an EUV mask used in the manufacture of semiconductor devices such as LSIs, a substrate with a multilayer reflective film for an EUV mask blank used in the manufacture of an EUV mask blank, and a method for manufacturing the same.

Background Art

[0002] In the manufacturing process of semiconductor devices (semiconductor devices), photolithography technology is repeatedly used in which exposure light is irradiated onto a transfer mask, and the circuit pattern formed on the mask is transferred onto a semiconductor substrate (semiconductor wafer) through a reduction projection optical system. Conventionally, the wavelength of the exposure light has been mainly 193 nm using argon fluoride (ArF) excimer laser light, and by adopting a process called multi-patterning in which a plurality of exposure processes and processing processes are combined, ultimately, patterns with dimensions smaller than the exposure wavelength have been formed.

[0003] However, due to the continuous miniaturization of device patterns, the formation of further fine patterns has been required, and thus EUV (Extreme UltraViolet) lithography technology using EUV light with a wavelength shorter than that of ArF excimer laser light has been developed. EUV light is light with a wavelength of, for example, about 10 to 20 nm, more specifically, light with a wavelength near 13.5 nm. Since this EUV light has extremely low permeability to substances and cannot use conventional transmissive projection optical systems or masks, reflective optical elements are used. Therefore, reflective masks for pattern transfer have also been proposed. A reflective mask is one in which a multilayer reflective film that reflects EUV light is formed on a substrate, and an absorber film that absorbs EUV light is formed in a pattern on the multilayer reflective film. On the other hand, the state before patterning the absorber film (including the state in which a resist layer is formed) is called a reflective mask blank, and this is used as a material for the reflective mask. Generally, a reflective mask and a reflective mask blank that reflect EUV light are called an EUV mask and an EUV mask blank, respectively.

[0004] The EUV mask blank has a basic structure including a substrate with low thermal expansion, a multilayer reflective film formed thereon that reflects EUV light, and an absorber film formed thereon that absorbs EUV light. As the multilayer reflective film, usually, a Mo / Si multilayer reflective film that obtains the necessary reflectivity for EUV light by alternately laminating a molybdenum (Mo) film and a silicon (Si) film is used. Further, as a protective film for protecting the multilayer reflective film, a ruthenium (Ru) film or a film made of a mixture of Ru and niobium (Nb) or zirconium (Zr) is formed on the outermost layer of the multilayer reflective film. On the other hand, as the absorber film, a material mainly composed of tantalum (Ta) or chromium (Cr) having a relatively large attenuation coefficient value for EUV light is used.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] For the protective layer formed as the outermost layer of the multilayer reflective film, in combination with the Si / Mo laminated portion, it is required to obtain a high reflectivity for EUV light as the multilayer reflective film. Generally, if the protective layer is made thinner, the reflectivity can be increased. However, when the protective layer is made thinner, when heat is applied to the multilayer reflective film during the mask processing process or during exposure with EUV light using the mask, oxygen in the atmosphere diffuses into the protective layer and reaches the Si / Mo laminated portion. In particular, when the outermost layer of the Si / Mo laminated portion is a Si layer, silicon oxide is formed, resulting in a decrease in reflectivity. Also, in such a case, the protective layer may expand and peel off due to oxidation.

[0007] In addition, the protective layer is required to have resistance in etching the absorber film formed on the protective layer and in etching for removing the hard mask film formed as needed as an etching mask when etching the absorber film. For example, in the case of a Ta-based absorber film, dry etching using Cl2 gas is used, and in the case of a Cr-based hard mask film, dry etching using a mixture of Cl2 gas and O2 gas is used. On the other hand, Ru is etched by dry etching using an etching gas containing O2 gas. Therefore, the protective layer is made of a mixture of Ru and Nb or Zr to ensure resistance to dry etching using an etching gas containing O2 gas. However, in a material obtained by adding Nb or Zr to Ru, since Nb or Zr is easily oxidized, the surface of the protective layer is likely to be rough, and since oxygen in the atmosphere easily diffuses into the protective layer, the above-described problems are likely to occur. Therefore, it has been difficult to make such a protective layer thin.

[0008] The present invention has been made to solve the above problems, and an object thereof is to provide a substrate with a multilayer reflective film for an EUV mask blank having a multilayer reflective film that has necessary etching resistance and high reflectivity and is difficult to reduce in reflectivity even when heat is applied, a method for manufacturing the same, and an EUV mask blank.

Means for Solving the Problems

[0009] As a result of intensive studies to solve the above problems, the inventors configured the multilayer reflective film used for the EUV mask blank to have a Si / Mo stacked portion in which Si layers and Mo layers are alternately stacked, and a protective layer containing Ru formed in contact with the Si / Mo stacked portion as the uppermost layer of the multilayer reflective film. This protective layer is composed of a lower layer formed of Ru and provided in contact with the Si / Mo stacked portion, and an upper layer formed of a material containing Ru and one or more metals or semimetals different from Ru and provided on the side farthest from the substrate. Preferably, by making the layer in contact with the protective layer of the Si / Mo stacked portion a Mo layer, an EUV mask blank substrate with a multilayer reflective film having necessary etching resistance and high reflectivity, and an EUV mask blank that is less likely to have a decrease in reflectivity even when heat is applied were found.

[0010] Then, when forming the multilayer reflective film of such an EUV mask blank substrate and EUV mask blank by sputtering, after forming the Si / Mo stacked portion, it was found that forming the protective layer without bringing the gas that reacts with the Si / Mo stacked portion into contact with the Si / Mo stacked portion is extremely important for achieving high reflectivity, and thus the present invention was completed.

[0011] Therefore, the present invention provides the following EUV mask blank substrate with a multilayer reflective film, its manufacturing method, and an EUV mask blank. 1. A substrate and a multilayer reflective film provided on the substrate, the multilayer reflective film having a Si / Mo stacked portion in which Si layers and Mo layers are alternately stacked, and a protective layer containing Ru formed in contact with the Si / Mo stacked portion as the uppermost layer of the multilayer reflective film. The protective layer is composed of two layers, a lower layer provided in contact with the Si / Mo stacked portion and an upper layer provided on the side farthest from the substrate. The lower layer is formed only of Ru, and the upper layer is formed of a material containing Ru and one or more metals or semimetals different from Ru. Between any one or more of the Si layer and the Mo layer in the Si / Mo laminated portion, a layer containing Si and N is formed in contact with both the Si layer and the Mo layer. The uppermost part of the multilayer reflective film is composed of, from the side away from the substrate, the protective layer, the Mo layer, the layer containing Si and N, and the Si layer. At the uppermost part of the multilayer reflective film composed of, from the side away from the substrate, the protective layer, the Mo layer, the layer containing Si and N, and the Si layer, the thickness of the protective layer is 4 nm or less, the thickness of the Mo layer is 1 nm or less, the thickness of the layer containing Si and N is 2 nm or less, and the thickness of the Si layer is 4 nm or less. A substrate with a multilayer reflective film for an EUV mask blank, characterized in that. 2. The substrate with a multilayer reflective film for an EUV mask blank according to 1, characterized in that the metal different from Ru is a transition metal having a standard oxidation-reduction potential lower than that of Ru. 3. The substrate with a multilayer reflective film for an EUV mask blank according to 1 or 2, characterized in that the upper layer is formed of a material containing Ru and one or more selected from Nb, Zr, Ti, Cr, and Si. 4. The substrate with a multilayer reflective film for an EUV mask blank according to any one of 1 to 3, characterized in that the upper layer is formed of a material containing Ru and one or more metals or semimetals having an etching rate slower than that of Ru in dry etching using an etching gas containing O2 gas and Cl2 gas. 5. The substrate with a multilayer reflective film for an EUV mask blank according to any one of 1 to 4, characterized in that the upper layer is formed of a material composed of Ru and one or more metals or semimetals different from Ru. 6. The substrate with a multilayer reflective film for an EUV mask blank according to any one of 1 to 4, characterized in that the upper layer further contains oxygen. 7. Upper The upper layer is formed of a material composed of Ru and one or more selected from Nb, Zr, and Cr. According to any one of 1 to 4 A substrate with a multilayer reflective film for an EUV mask blank. 8. In the Si / Mo laminated portion, from the substrate side, a three-layer laminated structure unit composed of a Si layer, a layer containing Si and N formed in contact with the Si layer, and a Mo layer formed in contact with the layer containing Si and N, or from the substrate side, a three-layer laminated structure unit composed of a Mo layer, a layer containing Si and N formed in contact with the Mo layer, and a Si layer formed in contact with the layer containing Si and N contains 30 or more, characterized in that it is 1 to 7 The substrate with a multilayer reflective film for an EUV mask blank according to any one of 9 . In the Si / Mo laminated portion, from the substrate side, a Si layer, a layer containing Si and N formed in contact with the Si layer, a Mo layer formed in contact with the layer containing Si and N, and a layer containing Si and N formed in contact with the Mo layer A four-layer laminated structure unit composed of contains 30 or more, characterized in that it is 1 to 7 The substrate with a multilayer reflective film for an EUV mask blank according to any one of 10 . The peak reflectivity of the multilayer reflective film at an incident angle of 6° of EUV light in the wavelength range of 13.4 to 13.6 nm is 65% or more, characterized in that it is 1 to 9 The substrate with a multilayer reflective film for an EUV mask blank according to any one of 11 . 1 to 10 A method for manufacturing a substrate with a multilayer reflective film for an EUV mask blank according to any one of (A) A step of forming the Si / Mo laminated portion by sputtering including, the sputtering One or more Mo targets and Si targets can be mounted respectively, Power can be applied to the Mo target and the Si target separately, The arrangement of the substrate and each target is an offset arrangement, It does not have a member that shields between each target and the substrate, The substrate can be rotated along the main surface, and A nitrogen-containing gas can be introduced A method for manufacturing a substrate with a multilayer reflective film for an EUV mask blank, characterized by being carried out using a magnetron sputtering apparatus equipped with a chamber. 12 .1 to 10 A method for manufacturing a substrate with a multilayer reflective film for an EUV mask blank according to any one of the above, (B) A step of forming the protective layer by sputtering including, and the sputtering is One or more Ru targets and one or more targets containing one or more metals or semimetals different from Ru can be mounted respectively, Power can be applied separately to the Ru target and the target containing one or more metals or semimetals different from Ru, The arrangement of the substrate and each target is an offset arrangement, It has no member for shielding between each target and the substrate, The substrate can be rotated along the main surface, and An oxygen-containing gas can be introduced A method for manufacturing a substrate with a multilayer reflective film for an EUV mask blank, characterized by being carried out using a magnetron sputtering apparatus equipped with a chamber. 13 .1 to 10 An EUV mask blank, characterized in that on the multilayer reflective film of the substrate with a multilayer reflective film for an EUV mask blank according to any one of the above, in contact with the protective layer, it has an absorber film containing Ta or Cr. 14 .1 to 10 An EUV mask blank, characterized in that on the multilayer reflective film of the substrate with a multilayer reflective film for an EUV mask blank according to any one of the above, in contact with the protective layer, it has an absorber film containing Ta and not containing Cr, and on the absorber film, it has a hard mask film containing Cr and functioning as an etching mask when dry-etching the absorber film. Further, the present invention is related to the following substrate with a multilayer reflective film for an EUV mask blank, its manufacturing method and EUV mask blank. [1]. A substrate having a multilayer reflective film provided thereon, the multilayer reflective film having a Si / Mo stacked portion in which Si layers and Mo layers are alternately stacked, and on the Si / Mo stacked portion, a protective layer containing Ru formed in contact with the Si / Mo stacked portion as the uppermost layer of the multilayer reflective film, the protective layer having a lower layer provided in contact with the Si / Mo stacked portion and an upper layer provided on the side farthest from the substrate, the lower layer being formed of a material containing Ru, and the upper layer being formed of a material containing Ru and one or more metals or semimetals different from Ru. A substrate with a multilayer reflective film for an EUV mask blank, characterized in that. [2]. The substrate with a multilayer reflective film for an EUV mask blank according to [1], characterized in that the metal different from Ru is a transition metal having a standard oxidation-reduction potential lower than that of Ru. [3]. The substrate with a multilayer reflective film for an EUV mask blank according to [1] or [2], characterized in that the upper layer is formed of a material containing Ru and one or more selected from Nb, Zr, Ti, Cr, and Si. [4]. The substrate with a multilayer reflective film for an EUV mask blank according to any one of [1] to [3], characterized in that the upper layer is formed of a material containing Ru and one or more metals or semimetals having an etching rate slower than that of Ru in dry etching using an etching gas containing O2 gas and Cl2 gas. [5]. The substrate with a multilayer reflective film for an EUV mask blank according to any one of [1] to [4], characterized in that the upper layer has a gradient composition in which the content of the metal or semimetal continuously increases toward the side away from the substrate in the thickness direction of the upper layer, or is composed of two or more sublayers, and the content of the metal or semimetal in each sublayer has a gradient composition that increases stepwise toward the side away from the substrate in the thickness direction of the upper layer. [6]. The substrate with a multilayer reflective film for an EUV mask blank according to any one of [1] to [5], characterized in that the upper layer further contains oxygen. [7]. The substrate with a multilayer reflective film for an EUV mask blank according to any one of [1] to [6], wherein a layer containing Si and N is formed in contact with both the Si layer and the Mo layer among any one or more between the Si layer and the Mo layer of the Si / Mo stacked portion. [8]. The substrate with a multilayer reflective film for an EUV mask blank according to [7], wherein the thickness of the layer containing Si and N is 2 nm or less. [9]. The substrate with a multilayer reflective film for an EUV mask blank according to any one of [1] to [8], wherein the layer in contact with the protective layer of the Si / Mo stacked portion is a Mo layer.

[10] . The substrate with a multilayer reflective film for an EUV mask blank according to [9], wherein the uppermost portion of the multilayer reflective film is composed of, from the side away from the substrate, the protective layer, the Mo layer, the layer containing Si and N, and the Si layer.

[11] . The substrate with a multilayer reflective film for an EUV mask blank according to

[10] , wherein at the uppermost portion, the thickness of the protective layer is 4 nm or less, the thickness of the Mo layer is 1 nm or less, the thickness of the layer containing Si and N is 2 nm or less, and the thickness of the Si layer is 4 nm or less.

[12] . The substrate with a multilayer reflective film for an EUV mask blank according to any one of [1] to

[11] , wherein in the Si / Mo stacked portion, from the substrate side, a three-layer stacked structure unit composed of a Si layer, a layer containing Si and N formed in contact with the Si layer, and a Mo layer formed in contact with the layer containing Si and N, or a three-layer stacked structure unit composed of a Mo layer, a layer containing Si and N formed in contact with the Mo layer, and a Si layer formed in contact with the layer containing Si and N is included in 30 or more.

[13] . The substrate with a multilayer reflective film for an EUV mask blank according to any one of [1] to

[11] , wherein in the Si / Mo stacked portion, from the substrate side, a four-layer stacked structure unit composed of a Si layer, a layer containing Si and N formed in contact with the Si layer, a Mo layer formed in contact with the layer containing Si and N, and a layer containing Si and N formed in contact with the Mo layer is included in 30 or more.

[14] . The substrate with a multilayer reflective film for an EUV mask blank according to any one of [1] to

[13] , wherein the peak reflectivity of the multilayer reflective film at an incident angle of 6° of EUV light in the wavelength range of 13.4 to 13.6 nm is 65% or more.

[15] . A method for manufacturing a substrate with a multilayer reflective film for an EUV mask blank according to any one of [1] to

[14] , comprising: (A) a step of forming the Si / Mo stacked portion by sputtering including performing the sputtering in a magnetron sputtering apparatus equipped with one or more Mo targets and one or more Si targets respectively, applying power separately to the Mo target and the Si target, wherein the arrangement of the substrate and each target is an offset arrangement, having no member for shielding between each target and the substrate, being able to rotate the substrate along the main surface, and being able to introduce a nitrogen-containing gas characterized in that it is carried out in a magnetron sputtering apparatus.

[16] . A method for manufacturing a substrate with a multilayer reflective film for an EUV mask blank according to any one of [1] to

[14] , comprising: (B) a step of forming the protective layer by sputtering including performing the sputtering in a magnetron sputtering apparatus equipped with one or more Ru targets and one or more targets containing one or more metals or semimetals different from Ru respectively, applying power separately to the Ru target and the target containing one or more metals or semimetals different from Ru, wherein the arrangement of the substrate and each target is an offset arrangement, having no member for shielding between each target and the substrate, being able to rotate the substrate along the main surface, and being able to introduce an oxygen-containing gas A method for manufacturing a substrate with a multilayer reflective film for an EUV mask blank, characterized by being carried out using a magnetron sputtering apparatus equipped with a chamber.

[17] . A method for manufacturing a substrate with a multilayer reflective film for an EUV mask blank, which has a substrate and a multilayer reflective film provided on the substrate, and the multilayer reflective film has a Si / Mo stacked portion in which Si layers and Mo layers are alternately stacked, and on the Si / Mo stacked portion, a protective layer containing Ru formed in contact with the Si / Mo stacked portion, comprising: (A) A step of forming the Si / Mo stacked portion by sputtering, and (B) A step of forming the protective layer by sputtering and including: After the step (A), the step (B) is carried out without bringing a gas that reacts with the Si / Mo stacked portion into contact with the Si / Mo stacked portion formed in the step (A). A method for manufacturing a substrate with a multilayer reflective film for an EUV mask blank, characterized by this.

[18] . The manufacturing method according to

[17] , characterized in that the step (A) is carried out in one sputtering chamber, and the substrate on which the Si / Mo stacked portion is formed is moved from the one sputtering chamber to another sputtering chamber, and the step (B) is carried out in the other sputtering chamber.

[19] . A transfer chamber that can communicate with each sputtering chamber individually or both sputtering chambers simultaneously is provided between the one and the other sputtering chambers, and the substrate on which the Si / Mo stacked portion is formed is moved from the one sputtering chamber to the other sputtering chamber via the transfer chamber. The manufacturing method according to

[18] , characterized by this.

[20] . The manufacturing method according to

[19] , characterized in that both the movement from the one sputtering chamber to the transfer chamber and the movement from the transfer chamber to the other sputtering chamber are carried out under vacuum.

[21] . An EUV mask blank, characterized by having an absorber film containing Ta or Cr on the multilayer reflective film of the substrate with a multilayer reflective film for an EUV mask blank according to any one of [1] to

[14] . On the multilayer reflective film of the substrate with a multilayer reflective film for an EUV mask blank according to any one of [1] to

[14] in

[22] , there is an absorber film containing Ta and not containing Cr, and on the absorber film, there is a hard mask film containing Cr and functioning as an etching mask when dry-etching the absorber film. The EUV mask blank is characterized by this.

Effect of the Invention

[0012] According to the present invention, it is possible to provide a substrate with a multilayer reflective film for an EUV mask blank and an EUV mask blank having a multilayer reflective film that has necessary etching resistance and high reflectivity and is difficult for the reflectivity to decrease even when heat is applied.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiment for Carrying Out the Invention

[0014] Hereinafter, the present invention will be described in more detail. The substrate with a multilayer reflective film for an EUV mask blank of the present invention has a substrate and a multilayer reflective film formed on the substrate (on one main surface (the front surface)), specifically, a multilayer reflective film that reflects exposure light, that is, a multilayer reflective film that reflects EUV light. The multilayer reflective film may be provided in contact with one main surface of the substrate, or an underlayer film may be provided between the substrate and the multilayer reflective film. The wavelength of EUV light used in EUV lithography using EUV light as exposure light is 13 to 14 nm, and usually, it is light having a wavelength of about 13.5 nm (for example, 13.4 to 13.6 nm).

[0015] FIG. 1 is a cross-sectional view of an example of a substrate with a multilayer reflective film for an EUV mask blank of the present invention with intermediate portions omitted. This substrate 10 with a multilayer reflective film for an EUV mask blank has a multilayer reflective film 2 formed in contact with one main surface on one main surface of the substrate 1.

[0016] The substrate preferably has low thermal expansion characteristics for EUV light exposure. For example, the coefficient of thermal expansion is within ±2×10 -8 / °C, preferably within the range of ±5×10 -9 / °C. It is also preferable to use a substrate with a sufficiently planarized surface. The surface roughness of the main surface of the substrate is preferably 0.5 nm or less, particularly 0.2 nm or less, in terms of RMS value. Such surface roughness can be obtained by polishing the substrate or the like.

[0017] The multilayer reflective film is a film that reflects EUV light, which is the exposure light, in an EUV mask. In the present invention, the multilayer reflective film has a Si / Mo stacked portion composed of a multilayer in which Si (silicon) layers and Mo (molybdenum) layers are alternately stacked. In this Si / Mo stacked portion, a layer of Si, which is a material having a relatively high refractive index with respect to EUV light, and a layer of Mo, which is a material having a relatively low refractive index with respect to EUV light, are periodically stacked. Here, the Si layer and the Mo layer are each a layer formed of single silicon and single molybdenum, respectively. The number of stacked layers of the Si layer and the Mo layer is preferably 40 cycles or more (40 layers or more for each), and preferably 60 cycles or less (60 layers or less for each). The thicknesses of the Si layer and the Mo layer in the Si / Mo stacked portion are appropriately set according to the exposure wavelength. The thickness of the Si layer is preferably 5 nm or less, and the thickness of the Mo layer is preferably 4 nm or less. The lower limit of the thickness of the Si layer is not particularly limited, but is usually 1 nm or more, and the lower limit of the thickness of the Mo layer is not particularly limited, but is usually 1 nm or more. The thicknesses of the Si layer and the Mo layer may be set so as to obtain a high reflectivity with respect to EUV light. Also, the thickness of each of the Si layer and the Mo layer may be constant or different in each layer. The total thickness of the Si / Mo stacked portion is usually about 250 to 450 nm.

[0018] In the present invention, in the Si / Mo stacked portion, it is preferable that a layer containing Si and N is formed in contact with both the Si layer and the Mo layer in any one or more of the interfaces between the Si layer and the Mo layer. The layer containing Si and N preferably does not contain oxygen. Specifically, a SiN layer (here, SiN means that the constituent elements consist only of Si and N) is suitable as the layer containing Si and N. The N content of the layer containing Si and N is preferably 1 atomic % or more, particularly preferably 5 atomic % or more, and preferably 60 atomic % or less, particularly preferably 57 atomic % or less. Also, the thickness of the layer containing Si and N is preferably 2 nm or less, and more preferably 1 nm or less. The lower limit of the thickness of the layer containing Si and N is not particularly limited, but is preferably 0.1 nm or more.

[0019] The layer containing Si and N is preferably provided at at least one location between the Si layer and the Mo layer that constitute the Si / Mo laminate. The layer containing Si and N may be provided at a part or all of the substrate side (lower side) of the Mo layer, or at a part or all of the side (upper side) spaced apart from the substrate of the Mo layer, but it is particularly preferable to provide it at all locations between the Si layer and the Mo layer that constitute the Si / Mo laminate.

[0020] In particular, from the viewpoint of obtaining a high reflectivity, in the Si / Mo laminate, from the substrate side, a three-layer laminate structural unit composed of a Si layer, a layer containing Si and N formed in contact with the Si layer, and a Mo layer formed in contact with the layer containing Si and N, or from the substrate side, a three-layer laminate structural unit composed of a Mo layer, a layer containing Si and N formed in contact with the Mo layer, and a Si layer formed in contact with the layer containing Si and N is preferably contained 30 or more, particularly 40 or more. Further, in the Si / Mo laminate, from the substrate side, a four-layer laminate structural unit composed of a Si layer, a layer containing Si and N formed in contact with the Si layer, a Mo layer formed in contact with the layer containing Si and N, and a layer containing Si and N formed in contact with the Mo layer is more preferably contained 30 or more, particularly 40 or more. The upper limit of both the three-layer laminate structural unit and the four-layer laminate structural unit is preferably 60 or less.

[0021] In the present invention, specific examples of the Si / Mo laminated portion include, for example, those shown in FIG. 1. In the multilayer reflective film 2 of the substrate 10 with the multilayer reflective film for EUV mask blank shown in FIG. 1, a Si / Mo laminated portion 21 is formed in contact with the substrate 1. In the Si / Mo laminated portion 21, Si layers 211 and Mo layers 212 are alternately laminated. In this case, the Si layer 211 is on the side closest to the substrate 1, and the Mo layer 212 is on the side farthest from the substrate 1. And, between all of the Si layer 211 and the Mo layer 212, a layer 213 containing Si and N is formed in contact with both the Si layer 211 and the Mo layer 212. Therefore, in this case, a three-layer laminated structure unit of the Si layer 211, the layer 213 containing Si and N, and the Mo layer 212 is included from the substrate side, and also, a three-layer laminated structure unit of the Mo layer 212, the layer 213 containing Si and N, and the Si layer 211 is included from the substrate side. Furthermore, a four-layer laminated structure unit of the Si layer 211, the layer 213 containing Si and N, the Mo layer 212, and the layer 213 containing Si and N is included from the substrate side.

[0022] The Si / Mo laminated portion of the multilayer reflective film is formed by alternately laminating Si layers and Mo layers. FIG. 2 is a partially cut-away cross-sectional view for explaining a substrate with a multilayer reflective film for EUV mask blank having an ideal Si / Mo laminated portion and a protective layer, with intermediate portions omitted. FIG. 3 is a partially cut-away cross-sectional view showing a substrate with a multilayer reflective film for EUV mask blank having a conventional Si / Mo laminated portion and a protective layer, with intermediate portions omitted. When the Si / Mo laminated portion 21 of the multilayer reflective film 2 of the substrate 10 with the multilayer reflective film for EUV mask blank is formed by directly alternately laminating Si layers and Mo layers on the substrate 1, it is ideal that a state is formed in which the Si / Mo laminated portion 21 composed only of the Si layer 211 and the Mo layer 212, where the Si layer and the Mo layer are in contact, as shown in FIG. 2. With such a Si / Mo laminated portion 21, the theoretical reflectance by the Si / Mo laminated portion composed only of the Si layer and the Mo layer can be obtained.

[0023] However, although it is not impossible in principle to form a Si / Mo stacked portion with such a configuration, when it is formed by a practical method, in reality, as shown in FIG. 3, at the portion where the Si layer 211 and the Mo layer 212 are in contact, Si and Mo are mixed, and an interdiffusion layer 21a composed of Si and Mo is unintentionally formed at this portion. When such an interdiffusion layer composed of Si and Mo is formed, the reflectance decreases from the theoretical value obtained in the Si / Mo stacked portion composed only of the Si layer and the Mo layer. Furthermore, when heat is applied to the multilayer reflective film during the mask processing process or exposure with EUV light using a mask, etc., the interdiffusion layer composed of Si and Mo becomes thicker or the interdiffusion layer composed of Si and Mo changes, resulting in a further decrease in reflectance.

[0024] On the other hand, if a layer containing Si and N is formed in contact with both the Si layer and the Mo layer between the Si layer and the Mo layer, the formation of an interdiffusion layer composed of Si and Mo that causes a decrease in reflectance is suppressed between the Si layer and the Mo layer. Therefore, the decrease in reflectance from the theoretical value obtained in the Si / Mo stacked portion composed only of the Si layer and the Mo layer is suppressed, and a higher reflectance is achieved compared to the conventional case. Usually, an interdiffusion layer composed of Si and Mo as described above is formed in contact with both the Si layer and the Mo layer between the Si layer and the Mo layer where the layer containing Si and N is not formed. However, in the Si / Mo stacked portion of the multilayer reflective film of the present invention, the formation of the interdiffusion layer composed of Si and Mo is suppressed between the Si layer and the Mo layer where the layer containing Si and N is formed. Therefore, compared with the conventional multilayer reflective film in which the interdiffusion layer composed of Si and Mo is formed throughout between the Si layer and the Mo layer, the reduction in reflectance due to heat is suppressed. From this perspective, the layer containing Si and N may be formed in part between the Si layer and the Mo layer, but it is more advantageous if it is formed in a larger portion between the Si layer and the Mo layer, and it is particularly advantageous if it is formed throughout between the Si layer and the Mo layer.

[0025] In the present invention, the multilayer reflective film has a protective layer in contact with the Si / Mo laminated portion as the uppermost layer of the multilayer reflective film. When the outermost layer of the multilayer reflective film is a Si layer or a Mo layer, it will be etched by dry etching using a gas containing fluorine. Therefore, it is effective to provide a protective layer on the Si / Mo laminated portion. The protective layer is also called a capping layer and functions as an etching stopper when forming an absorber pattern from the absorber film formed thereon. Therefore, a material having etching characteristics different from those of the absorber film is used for the protective layer. Further, the protective layer is preferably also effective for protecting the multilayer reflective film when correcting the absorber pattern.

[0026] In the present invention, the protective layer has a lower layer provided in contact with the Si / Mo laminated portion and an upper layer provided on the side farthest from the substrate. Specifically, as the protective layer, for example, those shown in FIG. 1 can be mentioned. In the multilayer reflective film 2 of the substrate 10 with the multilayer reflective film for EUV mask blank shown in FIG. 1, a protective layer 22 is formed in contact with the Si / Mo laminated portion 21, and the protective layer 22 is composed of a lower layer 221 and an upper layer 222 from the substrate 1 side.

[0027] As the material of the protective layer, a material containing ruthenium (Ru) is used. The lower layer is a layer formed of Ru (Ru layer), and the upper layer is a layer formed of a material containing Ru and one or more metals or semimetals different from Ru. By doing so, it is possible to suppress the diffusion of oxygen from the protective layer to the Si / Mo laminated portion, improve the etching characteristics, and impart washing resistance. The metal different from Ru in the upper layer has a standard oxidation-reduction potential of Ru 2+ +2e -It is preferably a metal having a standard redox potential lower than that of Ru (in particular, a metal that forms oxides more easily than Ru when mixed with Ru), and more preferably a transition metal. As metals different from Ru, Nb, Zr, Ti, Cr, etc. are preferable, and as metalloids, Si, etc. is preferable. The layer formed of a material containing one or more metals or metalloids different from Ru preferably contains these one or more together with Ru. By doing so, when the protective layer is oxidized from the side away from the Si / Mo laminated portion, the metalloid contained in the upper layer or the metal having a standard redox potential lower than that of Ru is oxidized first, thereby protecting the lower layer formed of Ru in the upper layer, preventing oxygen from reaching the lower layer, suppressing the oxidation of the lower layer, and further suppressing the diffusion of oxygen to the Si / Mo laminated portion formed in contact with the protective layer (lower layer).

[0028] The content (atomic %) of one or more metals or metalloids different from Ru in the upper layer is preferably the same as or less than the content of Ru. Also, the lower limit of the content (atomic %) of one or more metals or metalloids different from Ru in the upper layer is not particularly limited, but is preferably 0.1 atomic % or more, and more preferably 1 atomic % or more. The upper layer may further contain other elements other than metals or metalloids. In particular, since the metalloid in the upper layer and the metal having a standard redox potential lower than that of Ru are stabilized by being oxidized, the upper layer may contain oxygen.

[0029] The upper layer is preferably formed of a material containing Ru and one or more metals or metalloids with an etching rate slower than that of Ru in dry etching using an etching gas containing O2 gas, particularly dry etching using an etching gas containing O2 gas and Cl2 gas. When the protective layer is a Ru layer, it will be etched in dry etching using a gas containing oxygen gas as the etching gas. In contrast, if the protective layer is a layer of a mixture of Ru and Nb or Zr, it is possible to ensure resistance to dry etching using an etching gas containing O2 gas, particularly dry etching using an etching gas containing O2 gas and Cl2 gas, which is commonly used for etching materials containing chromium, and resistance to O3 gas used in mask manufacturing processes and the like. However, in materials with Nb or Zr added to Ru, since Nb and Zr are easily oxidized, the surface of the protective layer is likely to become rough, and since oxygen in the atmosphere easily diffuses into the protective layer, oxygen reaches the Si / Mo laminated portion. In particular, when the top layer of the Si / Mo laminated portion is a Si layer, silicon oxide is formed, resulting in a decrease in reflectivity. Also, in such cases, the protective layer may expand and peel off due to oxidation. Furthermore, since a high reflectivity is required for the multilayer reflective film, it is advantageous for the thickness of the protective layer formed of a material containing Ru with a large attenuation coefficient to be thin. However, with respect to the above-described oxygen diffusion, it is preferable for the thickness of the protective layer to be thick. Therefore, when using only a material with Nb or Zr added to Ru, there is a limit to reducing the overall thickness of the protective layer.

[0030] In the present invention, on the side of the protective layer farthest from the substrate, a layer formed of a material containing Ru and one or more metals or semimetals having an etching rate slower than that of Ru in dry etching using an etching gas containing O2 gas, particularly dry etching using an etching gas containing O2 gas and Cl2 gas, which is commonly used for etching a material containing chromium, is disposed. On the side of the protective layer in contact with the Si / Mo stacked portion, a lower layer formed of Ru is disposed. In the upper layer, while ensuring resistance to dry etching using an etching gas containing O2 gas, particularly dry etching using an etching gas containing O2 gas and Cl2 gas, and resistance to O3 gas used in a mask manufacturing process or the like, the upper layer containing a metal that is more likely to form an oxide than Ru suppresses the arrival of oxygen to the lower layer. Also, by bringing the lower layer formed of Ru into contact with the Si / Mo stacked portion, diffusion of oxygen from the protective layer to the Si / Mo stacked portion can be suppressed. As a result, the multilayer reflective film has the required etching resistance and high reflectivity.

[0031] The thickness of the protective layer is preferably usually 5 nm or less, particularly 4 nm or less. The lower limit of the thickness of the protective layer is usually 2 nm or more. Among them, the thickness of the lower layer is preferably 0.5 nm or more, particularly 1 nm or more and 2 nm or less, particularly 1.5 nm or less, and the thickness of the upper layer is preferably 0.5 nm or more, particularly 1 nm or more and 3 nm or less, particularly 2 nm or less.

[0032] The upper layer of the protective layer of the present invention may each be a layer having a single composition (a composition whose composition does not change in the thickness direction), a layer having a gradient composition in which the content of a metal or semimetal continuously increases toward the side away from the substrate in the thickness direction, or a layer composed of two or more sub-layers, and the content of the metal or semimetal in each sub-layer has a gradient composition that increases stepwise toward the side away from the substrate in the thickness direction. However, it is preferably a layer having a gradient composition. When it is composed of two or more sub-layers, the types of metals or semimetals contained in each sub-layer can be made different.

[0033] The Si / Mo stacked layer may have the layer closest to the substrate of the multilayer reflective film as either an Si layer or an Mo layer. On the other hand, the layer farthest from the substrate may be either an Si layer or an Mo layer, but it is preferably an Mo layer, and it is preferable that the layer in contact with the protective layer of the Si / Mo stacked layer is an Mo layer.

[0034] When the layer in contact with the protective layer of the Si / Mo stacked layer is an Si layer, if a protective layer of a material containing Ru is directly laminated on the Si / Mo stacked layer, it is ideal that, as shown in FIG. 2, the Si layer 211 of the Si / Mo stacked layer 21 and the protective layer 22 are in contact with each other. In such a state, the decrease in the reflectivity of the multilayer reflective film 2 due to the protective layer 22 is limited, and a high reflectivity can be obtained.

[0035] However, although it is not impossible in principle to achieve such a state, when formed by a practical method, in reality, as shown in FIG. 3, at the portion where the Si layer 211 and the protective layer 22 are in contact, Si and Ru are mixed, and an interdiffusion layer 21b composed of Si and Ru is inadvertently formed at this portion. When such an interdiffusion layer composed of Si and Ru is formed, the reflectivity decreases due to the interdiffusion layer 21b composed of Si and Ru. Furthermore, when heat is applied to the multilayer reflective film during a mask processing process or exposure with EUV light using a mask, etc., the interdiffusion layer composed of Si and Ru becomes thicker, the interdiffusion layer composed of Si and Ru changes, and furthermore, when the protective layer of the material containing Ru is exposed to the atmosphere, not only the protective layer but also the Si layer is oxidized, resulting in a further decrease in reflectivity.

[0036] On the other hand, as shown in FIG. 1, when the layer in contact with the protective layer 22 of the Si / Mo stacked layer 21 is the Mo layer 212, an interdiffusion layer composed of Si and Ru that causes a decrease in reflectivity is not formed between the Si / Mo stacked layer and the protective layer of the material containing Ru. Therefore, a higher reflectivity is achieved compared to the case where the layer in contact with the protective layer of the Si / Mo stacked layer is an Si layer, and at the same time, the crystallinity of the Ru layer in contact with Mo is improved, and a dense Ru layer can be obtained.

[0037] When the layer in contact with the protective layer of the Si / Mo stacked portion is a Mo layer, it is preferable that a layer containing Si and N is formed in contact with both the Si layer closest to this Mo layer and the Mo layer in contact with the protective layer. Specifically, it is preferable that the uppermost part of the multilayer reflective film is composed of, from the side spaced apart from the substrate, a protective layer, a Mo layer, a layer containing Si and N, and a Si layer. The region between the Si layer closest to the Mo layer in contact with the protective layer of the Si / Mo stacked portion and the Mo layer in contact with the protective layer is easily affected by the protective layer, and when heat is applied to the multilayer reflective film, it is most easily affected by the heat. Therefore, an interdiffusion layer composed of Si and Mo is most likely to be formed. Therefore, forming a layer containing Si and N between the uppermost Si layer and Mo layer of the multilayer reflective film is particularly effective for obtaining a high reflectivity.

[0038] In this case, when forming a layer containing Si and N, even if the Mo layer in contact with the protective layer formed of a material containing Ru is formed thinly, if a protective layer formed of a material containing Ru is formed thereon, even if the protective layer formed of a material containing Ru is a relatively thin film, the protective layer formed of a material containing Ru, particularly the lower layer, becomes a stable state having a crystalline and dense structure. Therefore, the thickness of the Mo layer in contact with the protective layer formed of a material containing Ru is preferably 2 nm or less, and more preferably 1 nm or less. In particular, when the uppermost part of the multilayer reflective film is composed of, from the side spaced apart from the substrate, a protective layer, a Mo layer, a layer containing Si and N, and a Si layer, the thickness of the protective layer is preferably 4 nm or less, the thickness of the Mo layer is preferably 1 nm or less, the thickness of the layer containing Si and N is preferably 2 nm or less, and the thickness of the Si layer is preferably 4 nm or less.

[0039] In the present invention, the reflectivity of the multilayer reflective film can be set to 65% or more as the peak reflectivity at an incident angle of 6° of EUV light in the wavelength range of 13.4 to 13.6 nm. Even if a heat treatment, for example, a heat treatment at 200 °C for 10 minutes in an air atmosphere, is performed on the multilayer reflective film, the change (decrease) in reflectivity is small, and the peak reflectivity can be maintained at 65% or more even after the heat treatment.

[0040] As a method for forming the Si / Mo laminated portion, there are a sputtering method in which power is supplied to a target, an atmospheric gas is plasmaized (ionized) by the supplied power, and sputtering is performed, and an ion beam sputtering method in which an ion beam is irradiated onto the target. As the sputtering method, there are a DC sputtering method in which a DC voltage is applied to the target and an RF sputtering method in which a high-frequency voltage is applied to the target. The sputtering method is a film-forming method in which a sputtering gas is introduced into a chamber, a voltage is applied to the target, the gas is ionized, and the sputtering phenomenon by gas ions is utilized. In particular, the magnetron sputtering method is advantageous in terms of productivity. The power applied to the target may be DC or RF. In the case of DC, pulsed sputtering in which a negative bias applied to the target is inverted for a short time to prevent charge-up of the target is also included.

[0041] The Si / Mo laminated portion can be formed, for example, by a sputtering method using a sputtering apparatus capable of mounting a plurality of targets. Specifically, a silicon (Si) target for forming a Si layer and a layer containing Si and N, and a molybdenum (Mo) target for forming a Mo layer are used. As the sputtering gas, when forming the Si layer and the Mo layer, noble gases such as helium (He) gas, argon (Ar) gas, krypton (Kr) gas, and xenon (Xe) gas are used. When forming a layer containing Si and N, a nitrogen-containing gas such as nitrogen gas (N2 gas) is used together with the noble gas. The arrangement of the substrate and each target is an offset arrangement (an arrangement in which the vertical line passing through the center of the sputtering surface of each target does not coincide with the vertical line passing through the center of the film-forming surface of the substrate). By sequentially sputtering the Si target and the Mo target, the Si layer, the layer containing Si and N, and the Mo layer can be sequentially formed. Sputtering is preferably performed while rotating the substrate along the main surface. In this case, it is preferable not to provide a member such as a shutter in the chamber that shields between the target and the substrate. Note that the layer containing Si and N may be formed by reactive sputtering using a nitrogen-containing gas or by using a silicon compound target such as a silicon nitride target for the target.

[0042] The Si / Mo laminated portion (A) can be formed by a method including the step of forming the Si / Mo laminated portion by sputtering. In this case, in particular, this sputtering can be performed by mounting one or more Mo targets and Si targets respectively, power can be applied to the Mo target and the Si target separately, the arrangement of the substrate and each target is an offset arrangement, there is no member for shielding between each target and the substrate, the substrate can be rotated along the main surface, and it is preferably carried out in a magnetron sputtering apparatus provided with a chamber into which a nitrogen-containing gas can be introduced.

[0043] The protective layer can be formed by a sputtering method such as an ion beam sputtering method or a magnetron sputtering method in the same manner as the Si / Mo laminated portion. However, like the Si / Mo laminated portion, the magnetron sputtering method is advantageous.

[0044] The protective layer can be formed by a sputtering method using, for example, a sputtering apparatus capable of mounting a plurality of targets. Specifically, a ruthenium (Ru) target, a target of a metal or metalloid other than ruthenium (Ru) (for example, niobium (Nb), zirconium (Zr), titanium (Ti), chromium (Cr), silicon (Si), etc.), a target composed of ruthenium (Ru) and a metal or metalloid other than ruthenium (Ru) (for example, niobium (Nb), zirconium (Zr), titanium (Ti), chromium (Cr), silicon (Si), etc.) are used. As the sputtering gas, noble gases such as helium (He) gas, argon (Ar) gas, krypton (Kr) gas, xenon (Xe) gas, and, if necessary, reactive gases such as oxygen-containing gas, nitrogen-containing gas, carbon-containing gas are used. By setting the arrangement of the substrate and each target as an offset arrangement, sputtering can be performed with a single target or a plurality of targets can be sputtered simultaneously. The sputtering is preferably performed while rotating the substrate along the main surface.

[0045] For example, the lower layer can be formed by sputtering using a Ru target and a noble gas as a sputtering gas. On the other hand, the upper layer can be formed by sputtering using a Ru target and a target containing one or more metals or semimetals different from ruthenium (Ru), and a noble gas as a sputtering gas. In particular, when simultaneously sputtering a plurality of targets, a layer having a gradient composition can be formed by continuously or stepwise changing the ratio of the power applied to each target.

[0046] When the upper layer of the protective layer is further formed of a compound containing an element other than a metal or a semimetal, it can be formed by reactive sputtering using a reactive gas such as an oxygen-containing gas, a nitrogen-containing gas, or a carbon-containing gas together with a noble gas as a sputtering gas. In particular, when forming a layer containing oxygen, it is preferable to use oxygen gas (O2 gas). Also, the target may be a compound.

[0047] The protective layer (B) A step of forming the protective layer by sputtering can be formed by a method including this. In this case, in particular, this sputtering can be carried out with one or more Ru targets and one or more targets containing one or more metals or semimetals different from Ru, and power can be applied separately to the Ru target and the targets containing one or more metals or semimetals different from Ru. The arrangement of the substrate and each target is an offset arrangement, there is no member for shielding between each target and the substrate, the substrate can be rotated along the main surface, and it is preferably carried out in a magnetron sputtering apparatus provided with a chamber into which an oxygen-containing gas can be introduced.

[0048] Thus, the multilayer reflective film (A) A step of forming the Si / Mo laminated portion by sputtering, and (B) A step of forming the protective layer by sputtering It can be preferably formed thereby. In this case, for example, the step (A) is carried out in one sputtering chamber, and the substrate on which the Si / Mo laminated portion is formed is moved from one sputtering chamber to another sputtering chamber, and the step (B) can be carried out in the other sputtering chamber. However, when shifting from the step (A) to the step (B), if the Si / Mo laminated portion is exposed to an atmosphere containing oxygen such as in the air, an unnecessary oxide layer may be formed between the Si / Mo laminated portion and the protective layer, resulting in a decrease in reflectivity and peeling between layers. Therefore, when shifting from the step (A) to the step (B) after the step (A), it is preferable to shift to the step (B) without bringing the Si / Mo laminated portion formed in the step (A) into contact with a gas that reacts with the Si / Mo laminated portion, particularly a gas containing oxygen such as oxygen gas (O2 gas) (more specifically, exposing it to the air), and carry out the step (B).

[0049] As a method of carrying out the step (B) without bringing the Si / Mo laminated portion formed in the step (A) into contact with a gas that reacts with the Si / Mo laminated portion, specifically, the step (A) is carried out in one sputtering chamber, and when the substrate on which the Si / Mo laminated portion is formed is moved from one sputtering chamber to another sputtering chamber and the step (B) is carried out in the other sputtering chamber, a transfer chamber that can communicate with each sputtering chamber individually or both sputtering chambers simultaneously is provided between the first and second sputtering chambers, and the substrate on which the Si / Mo laminated portion is formed is moved from one sputtering chamber to the other sputtering chamber via the transfer chamber. At this time, it is preferable to carry out both the movement from the first sputtering chamber to the transfer chamber and the movement from the transfer chamber to the other sputtering chamber under an inert gas atmosphere or in a vacuum at normal pressure (atmospheric pressure) or reduced pressure (lower pressure than atmospheric pressure).

[0050] FIG. 4 is a conceptual diagram showing an example of a sputtering apparatus suitable for forming the multilayer reflective film of the present invention. This sputtering apparatus 100 includes a sputtering chamber 101 for forming a Si / Mo laminated portion by sputtering, a sputtering chamber 102 for forming a protective layer by sputtering, a transfer chamber 103 connected to both of the sputtering chambers 101 and 102, and a load lock chamber 104 connected to the transfer chamber 103. An opening / closing partition wall (not shown) is provided between the transfer chamber 103 and the load lock chamber 104, and opening / closing partition walls can be provided as needed between the sputtering chambers 101 and 102 and the transfer chamber 103, respectively.

[0051] When forming a multilayer reflective film with such a sputtering apparatus, for example, first, a substrate is introduced into the load lock chamber 104. After evacuating the load lock chamber 104, the partition wall is opened, and the substrate is moved to the sputtering chamber 101 via the transfer chamber 103 to form a Si / Mo laminated portion in the sputtering chamber 101. Next, the substrate with the Si / Mo laminated portion formed thereon is moved from the sputtering chamber 101 to the sputtering chamber 102 via the transfer chamber 103 to form a protective layer in the sputtering chamber 102. Next, the substrate with the Si / Mo laminated portion and the protective layer (multilayer reflective film) formed thereon is moved from the sputtering chamber 102 to the load lock chamber 104 via the transfer chamber 103, the partition wall is closed, the inside of the load lock chamber 104 is returned to normal pressure, and the substrate with the multilayer reflective film formed thereon is taken out, then a substrate with a multilayer reflective film for EUV mask blank can be obtained. By forming the multilayer reflective film in this way, step (B) can be carried out without bringing the gas that reacts with the Si / Mo laminated portion into contact with the Si / Mo laminated portion formed in step (A).

[0052] The substrate with a multilayer reflective film for EUV mask blank becomes an EUV mask blank by forming an absorber film on the multilayer reflective film.

[0053] The EUV mask blank of the present invention has an absorber film that absorbs exposure light formed on the multilayer reflective film of a substrate with a multilayer reflective film for EUV mask blanks. Specifically, it has an absorber film that absorbs EUV light and reduces the reflectivity. The absorber film is preferably provided in contact with a protective layer. The EUV mask blank may further have a hard mask film on the absorber film that functions as an etching mask when dry-etching the absorber film. On the other hand, under the other main surface (the back surface), which is the surface opposite to one main surface of the substrate, preferably in contact with the other main surface, a conductive film may be provided for electrostatically chucking the EUV mask to an exposure apparatus. In the present invention, one main surface of the substrate is defined as the front surface and the upper side, and the other main surface is defined as the back surface and the lower side. However, the front and back, and the upper and lower of the two are defined for convenience. One main surface and the other main surface are any of the two main surfaces (film-forming surfaces) of the substrate, and the front and back, and the upper and lower are interchangeable.

[0054] An EUV mask (mask for EUV exposure) having an absorber pattern (pattern of the absorber film) formed by patterning the absorber film is manufactured from an EUV mask blank (mask blank for EUV exposure). The EUV mask blank and the EUV mask are reflective mask blanks and reflective masks.

[0055] The absorber film is formed on the multilayer reflective film and is a film that absorbs EUV light, which is the exposure light, and reduces the reflectivity of the exposure light. In the EUV mask, a transfer pattern is formed by the difference in reflectivity between the portion where the absorber film is formed and the portion where the absorber film is not formed.

[0056] As the material of the absorber film, there is no limitation as long as it can absorb EUV light and is capable of pattern processing. Examples of the material of the absorber film include materials containing tantalum (Ta) or chromium (Cr). Further, the materials containing Ta or Cr may contain oxygen (O), nitrogen (N), carbon (C), boron (B), etc. Examples of the materials containing Ta include tantalum compounds such as Ta alone, TaO, TaN, TaON, TaC, TaCN, TaCO, TaCON, TaB, TaOB, TaNB, TaONB, TaCB, TaCNB, TaCOB, TaCONB. Specific examples of the materials containing Cr include chromium compounds such as Cr alone, CrO, CrN, CrON, CrC, CrCN, CrCO, CrCON, CrB, CrOB, CrNB, CrONB, CrCB, CrCNB, CrCOB, CrCONB.

[0057] The absorber film can be formed by sputtering, and magnetron sputtering is preferably used for sputtering. Specifically, it can be formed by sputtering using a metal target such as a chromium (Cr) target or a tantalum (Ta) target, or a metal compound target such as a chromium compound target or a tantalum compound target (a target containing a metal such as Cr or Ta and oxygen (O), nitrogen (N), carbon (C), boron (B), etc.), and using a noble gas such as helium (He) gas, argon (Ar) gas, krypton (Kr) gas, xenon (Xe) gas as the sputtering gas, or by reactive sputtering using a reactive gas such as an oxygen-containing gas, a nitrogen-containing gas, or a carbon-containing gas together with the noble gas.

[0058] On the side spaced apart from the substrate on the absorber film, preferably in contact with the absorber film, a hard mask film (etching mask film for the absorber film) having different etching characteristics from the absorber film may be provided. This hard mask film is a film that functions as an etching mask when dry-etching the absorber film. After forming the absorber pattern, this hard mask film may be left as a reflectivity reduction layer for reducing the reflectivity at the wavelength of light used in inspections such as pattern inspection, and also be removed so as not to remain on the EUV mask as part of the absorber film. Examples of the material of the hard mask film include materials containing chromium (Cr). The hard mask film formed of a material containing Cr is particularly suitable when the absorber film is formed of a material containing Ta and not containing Cr. When forming a layer (reflectivity reduction layer) mainly responsible for the function of reducing the reflectivity at the wavelength of light used in inspections such as pattern inspection on the absorber film, the hard mask film can be formed on the reflectivity reduction layer of the absorber film. The hard mask film can be formed, for example, by magnetron sputtering. The film thickness of the hard mask film is not particularly limited, but is usually about 5 to 20 nm.

[0059] The conductive film preferably has a sheet resistance of 100 Ω / sq or less, and there is no particular limitation on the material. Examples of the material of the conductive film include materials containing tantalum (Ta) or chromium (Cr). Also, the material containing Ta or Cr may contain oxygen (O), nitrogen (N), carbon (C), boron (B), etc. Examples of the material containing Ta include tantalum compounds such as Ta alone, TaO, TaN, TaON, TaC, TaCN, TaCO, TaCON, TaB, TaOB, TaNB, TaONB, TaCB, TaCNB, TaCOB, TaCONB. Specific examples of the material containing Cr include chromium compounds such as Cr alone, CrO, CrN, CrON, CrC, CrCN, CrCO, CrCON, CrB, CrOB, CrNB, CrONB, CrCB, CrCNB, CrCOB, CrCONB.

[0060] The film thickness of the conductive film only needs to function as an electrostatic chuck and is not particularly limited, but is usually about 5 to 100 nm. The film thickness of the conductive film is preferably formed so that the film stress is balanced with the multilayer reflective film and the absorber pattern after being formed as an EUV mask, that is, after the absorber pattern is formed. The conductive film may be formed before forming the multilayer reflective film, or may be formed after forming all the films on the multilayer reflective film side of the substrate. Alternatively, after forming a part of the films on the multilayer reflective film side of the substrate, the conductive film may be formed, and then the remaining films on the multilayer reflective film side of the substrate may be formed. The conductive film can be formed, for example, by a magnetron sputtering method.

[0061] Furthermore, the EUV mask blank may have a resist film formed on the side farthest from the substrate. The resist film is preferably an electron beam (EB) resist.

Example

[0062] Hereinafter, the present invention will be specifically described with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0063] [Example 1] A multilayer reflective film composed of a Si / Mo laminated portion and a protective layer containing Ru was formed on a substrate made of a low thermal expansion material with a thermal expansion coefficient in the range of ±5.0×10 -9 / °C, a surface roughness of the main surface of 0.1 nm or less in RMS value, and a flatness of the main surface of 100 nm in TIR value.

[0064] The Si / Mo laminated part was formed by magnetron sputtering using a Si target and a Mo target as targets and Ar gas and N2 gas as sputtering gases. One Si target and one Mo target were each mounted on a magnetron sputtering apparatus, and the arrangement of the substrate and each target was an offset arrangement, and the substrate was rotated during formation. First, only Ar gas was flowed into the sputtering chamber, and only the Si target was discharged to form a Si layer with a set thickness of 3.5 nm. Next, Ar gas and N2 gas were flowed into the sputtering chamber, and only the Si target was discharged to form a SiN layer with a set thickness of 0.5 nm. Next, only Ar gas was flowed into the sputtering chamber, and only the Mo target was discharged to form a Mo layer with a set thickness of 3.0 nm. The formation of these Si layer, SiN layer, and Mo layer was defined as one cycle, and the formation of these three layers was repeated a total of 40 cycles. Thereafter, Ar gas and N2 gas were flowed into the sputtering chamber, and only the Si target was discharged to form a SiN layer with a set thickness of 0.5 nm. Next, only Ar gas was flowed into the sputtering chamber, and only the Si target was discharged to form a Si layer with a set thickness of 2.3 nm. Next, Ar gas and N2 gas were flowed into the sputtering chamber, and only the Si target was discharged to form a SiN layer with a set thickness of 0.5 nm. Next, only Ar gas was flowed into the sputtering chamber, and only the Mo target was discharged to form a Mo layer with a set thickness of 0.5 nm, resulting in the Si / Mo laminated part.

[0065] The protective layer was formed by magnetron sputtering using a Ru target and a Nb target as targets and Ar gas as a sputtering gas. One Ru target and one Nb target were each mounted on a magnetron sputtering apparatus different from the magnetron sputtering apparatus that formed the Si / Mo laminated portion. The arrangement of the substrate and each target was an offset arrangement, and it was formed while rotating the substrate. The movement of the substrate with the Si / Mo laminated portion formed from the magnetron sputtering apparatus that formed the Si / Mo laminated portion to the magnetron sputtering apparatus that forms the protective layer was carried out under vacuum via a transfer chamber communicating with both sputtering chambers. First, Ar gas was flowed into the sputtering chamber, and only the Ru target was discharged to form a Ru layer with a thickness of 2.0 nm as the lower layer. Next, Ar gas was flowed into the sputtering chamber, and the Ru target and the Nb target were simultaneously discharged to form a RuNb mixed layer with a thickness of 0.5 nm as the upper layer, resulting in a protective layer composed of two layers.

[0066] When the cross-section of the obtained multilayer reflective film was observed with a transmission electron microscope (TEM), on the upper part of the multilayer reflective film, in order from the surface side (the side away from the substrate), a RuNb mixed layer with a thickness of 0.5 nm, a Ru layer with a thickness of 2.0 nm, a Mo layer with a thickness of 0.5 nm, a SiN layer with a thickness of 0.5 nm, a Si layer with a thickness of 2.3 nm, a SiN layer with a thickness of 0.5 nm, a Mo layer with a thickness of 3.0 nm, and a SiN layer with a thickness of 0.5 nm were observed. Also, for the multilayer reflective film obtained by the same method, heat treatment was carried out in an air atmosphere at 200 °C for 10 minutes, and when the cross-section of the multilayer reflective film was observed in the same manner, it was the same as before the heat treatment. Further, when the peak reflectivity at an incident angle of 6° of EUV light in the wavelength range of 13.4 to 13.6 nm was measured before and after the heat treatment, it was 67% before the heat treatment and 65% after the heat treatment, and both were high reflectivities of 65% or more.

[0067] [Example 2] The coefficient of thermal expansion is ±5.0×10 -9A multilayer reflective film composed of a Si / Mo laminated portion and a protective layer containing Ru was formed on a substrate made of a low thermal expansion material within the range of / °C, with the surface roughness of the main surface being 0.1 nm or less in RMS value and the flatness of the main surface being 100 nm in TIR value.

[0068] The Si / Mo laminated portion was formed by magnetron sputtering using a Si target and a Mo target as targets and Ar gas and N2 gas as sputtering gases. One Si target and one Mo target were each mounted on a magnetron sputtering apparatus, and the arrangement of the substrate and each target was an offset arrangement, and the substrate was formed while rotating. First, only Ar gas was flowed into the sputtering chamber, and only the Si target was discharged to form a Si layer with a set thickness of 3.5 nm. Next, Ar gas and N2 gas were flowed into the sputtering chamber, and only the Si target was discharged to form a SiN layer with a set thickness of 0.5 nm. Next, only Ar gas was flowed into the sputtering chamber, and only the Mo target was discharged to form a Mo layer with a set thickness of 3.0 nm. The formation of these Si layer, SiN layer, and Mo layer was defined as one cycle, and the formation of these three layers was repeated a total of 40 cycles. Thereafter, Ar gas and N2 gas were flowed into the sputtering chamber, and only the Si target was discharged to form a SiN layer with a set thickness of 0.5 nm. Next, only Ar gas was flowed into the sputtering chamber, and only the Si target was discharged to form a Si layer with a set thickness of 2.3 nm. Next, Ar gas and N2 gas were flowed into the sputtering chamber, and only the Si target was discharged to form a SiN layer with a set thickness of 0.5 nm. Next, only Ar gas was flowed into the sputtering chamber, and only the Mo target was discharged to form a Mo layer with a set thickness of 0.5 nm to form the Si / Mo laminated portion.

[0069] The protective layer was formed by magnetron sputtering using a Ru target and a Nb target as targets and Ar gas as a sputtering gas. One Ru target and one Nb target were each mounted on a magnetron sputtering apparatus different from the magnetron sputtering apparatus that formed the Si / Mo laminated portion, and the arrangement of the substrate and each target was an offset arrangement, and it was formed while rotating the substrate. The movement of the substrate on which the Si / Mo laminated portion was formed from the magnetron sputtering apparatus that formed the Si / Mo laminated portion to the magnetron sputtering apparatus that formed the protective layer was carried out under vacuum via a transfer chamber communicating with both sputtering chambers. First, Ar gas was flowed into the sputtering chamber, and only the Ru target was discharged to form a Ru layer with a thickness of 1.0 nm as the lower layer. Next, Ar gas was flowed into the sputtering chamber, and the Ru target and the Nb target were discharged simultaneously. At this time, the power applied to the Nb target was gradually increased to form a gradient composition in which the Nb content continuously increased toward the side away from the substrate in the thickness direction, and a RuNb mixed layer with a thickness of 1.5 nm was formed as the upper layer to form a protective layer composed of two layers.

[0070] When the cross-section of the obtained multilayer reflective film was observed with a transmission electron microscope (TEM), on the upper part of the multilayer reflective film, in order from the surface side (the side away from the substrate), a RuNb mixed layer with a thickness of 1.5 nm, a Ru layer with a thickness of 1.0 nm, a Mo layer with a thickness of 0.5 nm, a SiN layer with a thickness of 0.5 nm, a Si layer with a thickness of 2.3 nm, a SiN layer with a thickness of 0.5 nm, a Mo layer with a thickness of 3.0 nm, and a SiN layer with a thickness of 0.5 nm were observed. Further, the multilayer reflective film obtained by the same method was heat-treated in an air atmosphere at 200 °C for 10 minutes, and the cross-section of the multilayer reflective film was observed in the same manner. As a result, it was the same as before the heat treatment. Also, when the peak reflectance at an incident angle of 6° of EUV light in the wavelength range of 13.4 to 13.6 nm was measured before and after the heat treatment, it was 67% before the heat treatment and 65% after the heat treatment, and both were high reflectances of 65% or more.

[0071] [Example 3] The coefficient of thermal expansion is ±5.0×10 -9A multilayer reflective film composed of a Si / Mo laminated portion and a protective layer containing Ru was formed on a substrate made of a low thermal expansion material within the range of / °C, with the surface roughness of the main surface being 0.1 nm or less in RMS value and the flatness of the main surface being 100 nm in TIR value.

[0072] For the Si / Mo laminated portion, a Si target and a Mo target were used as targets, and Ar gas and N2 gas were used as sputtering gases, and it was formed by magnetron sputtering. One Si target and one Mo target were each mounted on a magnetron sputtering apparatus, and the arrangement of the substrate and each target was set as an offset arrangement, and it was formed while rotating the substrate. First, only Ar gas was flowed into the sputtering chamber, and only the Si target was discharged to form a Si layer with a set thickness of 3.5 nm. Next, Ar gas and N2 gas were flowed into the sputtering chamber, and only the Si target was discharged to form a SiN layer with a set thickness of 0.5 nm. Next, only Ar gas was flowed into the sputtering chamber, and only the Mo target was discharged to form a Mo layer with a set thickness of 3.0 nm. The formation of these Si layer, SiN layer, and Mo layer was defined as one cycle, and the formation of these three layers was repeated 40 cycles in total. Thereafter, Ar gas and N2 gas were flowed into the sputtering chamber, and only the Si target was discharged to form a SiN layer with a set thickness of 0.5 nm. Next, only Ar gas was flowed into the sputtering chamber, and only the Si target was discharged to form a Si layer with a set thickness of 2.3 nm. Next, Ar gas and N2 gas were flowed into the sputtering chamber, and only the Si target was discharged to form a SiN layer with a set thickness of 0.5 nm. Next, only Ar gas was flowed into the sputtering chamber, and only the Mo target was discharged to form a Mo layer with a set thickness of 0.5 nm to form the Si / Mo laminated portion.

[0073] The protective layer was formed by magnetron sputtering using a Ru target and a Nb target as targets, and Ar gas and O2 gas as sputtering gases. One Ru target and one Nb target were each mounted on a magnetron sputtering apparatus different from the magnetron sputtering apparatus that formed the Si / Mo laminate. The arrangement of the substrate and each target was an offset arrangement, and the substrate was formed while rotating. The movement of the substrate with the Si / Mo laminate formed from the magnetron sputtering apparatus for forming the Si / Mo laminate to the magnetron sputtering apparatus for forming the protective layer was carried out under vacuum via a transfer chamber communicating with both sputtering chambers. First, only Ar gas was flowed into the sputtering chamber, and only the Ru target was discharged to form a Ru layer with a thickness of 1.0 nm as the lower layer. Next, Ar gas and O2 gas were flowed into the sputtering chamber, and the Ru target and the Nb target were discharged simultaneously. At this time, the power applied to the Nb target was gradually increased to form a gradient composition in which the Nb content continuously increased toward the side away from the substrate in the thickness direction. As the upper layer, a RuNbO mixed layer with a thickness of 1.5 nm was formed to obtain a protective layer composed of two layers.

[0074] When the cross-section of the obtained multilayer reflective film was observed with a transmission electron microscope (TEM), on the upper part of the multilayer reflective film, in order from the surface side (the side away from the substrate), a RuNbO mixed layer with a thickness of 1.5 nm, a Ru layer with a thickness of 1.0 nm, a Mo layer with a thickness of 0.5 nm, a SiN layer with a thickness of 0.5 nm, a Si layer with a thickness of 2.3 nm, a SiN layer with a thickness of 0.5 nm, a Mo layer with a thickness of 3.0 nm, and a SiN layer with a thickness of 0.5 nm were observed. Also, the multilayer reflective film obtained by the same method was heat-treated in an air atmosphere at 200 °C for 10 minutes, and the cross-section of the multilayer reflective film was observed in the same manner. The result was the same as before the heat treatment. Further, when the peak reflectance at an incident angle of 6° of EUV light in the wavelength range of 13.4 to 13.6 nm was measured before and after the heat treatment, it was 67% before the heat treatment and 65% after the heat treatment, and both had a high reflectance of 65% or more.

[0075] [Comparative Example 1] The coefficient of thermal expansion is ±5.0×10 -9A multilayer reflective film composed of a Si / Mo laminated portion and a protective layer containing Ru was formed on a substrate made of a low thermal expansion material within the range of / °C, with the surface roughness of the main surface being 0.1 nm or less in RMS value and the flatness of the main surface being 100 nm in TIR value.

[0076] The Si / Mo laminated portion was formed by magnetron sputtering using a Si target and a Mo target as targets and Ar gas as a sputtering gas. One Si target and one Mo target were each mounted on a magnetron sputtering apparatus, the arrangement of the substrate and each target was an offset arrangement, and it was formed while rotating the substrate. First, Ar gas was flowed into the sputtering chamber, and only the Si target was discharged to form a Si layer with a set thickness of 4.0 nm. Next, Ar gas was flowed into the sputtering chamber, and only the Mo target was discharged to form a Mo layer with a set thickness of 3.0 nm. The formation of these Si layer and Mo layer was defined as one cycle, and the formation of these two layers was repeated 40 cycles in total. Then, Ar gas was flowed into the sputtering chamber, and only the Si target was discharged to form a Si layer with a set thickness of 3.0 nm, resulting in the Si / Mo laminated portion.

[0077] The protective layer was formed by magnetron sputtering using a Ru target and a Nb target as targets and Ar gas as a sputtering gas. One Ru target and one Nb target were each mounted on a magnetron sputtering apparatus different from the magnetron sputtering apparatus that formed the Si / Mo laminated portion, the arrangement of the substrate and each target was an offset arrangement, and it was formed while rotating the substrate. The transfer of the substrate with the Si / Mo laminated portion formed from the magnetron sputtering apparatus that formed the Si / Mo laminated portion to the magnetron sputtering apparatus that formed the protective layer was carried out under vacuum via a transfer chamber communicating with both sputtering chambers. Ar gas was flowed into the sputtering chamber, and the Ru target and the Nb target were discharged simultaneously to form a RuNb mixed layer with a set thickness of 3.5 nm as the protective layer.

[0078] When the cross-section of the obtained multilayer reflective film was observed with a transmission electron microscope (TEM), on the upper part of the multilayer reflective film, in order from the surface side (the side away from the substrate), a RuNb mixed layer with a thickness of 2.5 nm, an interdiffusion layer in which Si and Ru with a thickness of 1.5 nm were mixed, a Si layer with a thickness of 2.5 nm, an interdiffusion layer in which Si and Mo with a thickness of 0.5 nm were mixed, a Mo layer with a thickness of 2.5 nm, and an interdiffusion layer in which Si and Mo with a thickness of 1.5 nm were mixed were observed. Also, for the multilayer reflective film obtained by the same method, heat treatment was carried out at 200 °C for 10 minutes in an air atmosphere, and when the cross-section of the multilayer reflective film was observed in the same way, on the upper part of the multilayer reflective film, in order from the surface side (the side away from the substrate), a RuNb mixed layer with a thickness of 2 nm, a SiO layer with a thickness of 2 nm, a RuNbSi mixed layer with a thickness of 2 nm, a Si layer with a thickness of 1.0 nm, an interdiffusion layer in which Si and Mo with a thickness of 0.5 nm were mixed, a Mo layer with a thickness of 2.0 nm, and an interdiffusion layer in which Si and Mo with a thickness of 2.0 nm were mixed were observed, and a SiO layer formed by oxygen in the air permeating through the RuNb mixed layer and reacting with the Si layer was formed. Also, when the peak reflectivity at an incident angle of 6° of EUV light in the wavelength range of 13.4 to 13.6 nm was measured before and after the heat treatment, it was 64% before the heat treatment and 60% after the heat treatment, and both were low reflectivities of less than 65%.

[0079] [Comparative Example 2] A multilayer reflective film composed of a Si / Mo laminated part and a protective layer containing Ru was formed on a substrate made of a low thermal expansion material with a thermal expansion coefficient in the range of ±5.0×10 -9 / °C, a surface roughness of the main surface of 0.1 nm or less in RMS value, and a flatness of the main surface of 100 nm in TIR value.

[0080] The Si / Mo stacked layer was formed by magnetron sputtering using a Si target and a Mo target as targets and Ar gas as a sputtering gas. One Si target and one Mo target were each mounted on a magnetron sputtering apparatus, and the arrangement of the substrate and each target was an offset arrangement, and it was formed while rotating the substrate. First, Ar gas was flowed into the sputtering chamber, and only the Si target was discharged to form a Si layer with a set thickness of 4.0 nm. Next, Ar gas was flowed into the sputtering chamber, and only the Mo target was discharged to form a Mo layer with a set thickness of 3.0 nm. The formation of these Si layer and Mo layer was defined as one cycle, and the formation of these two layers was repeated 40 cycles in total. Then, Ar gas was flowed into the sputtering chamber, and only the Si target was discharged to form a Si layer with a set thickness of 4.0 nm. Next, Ar gas was flowed into the sputtering chamber, and only the Mo target was discharged to form a Mo layer with a set thickness of 1.0 nm, thereby forming a Si / Mo stacked layer.

[0081] The protective layer was formed by magnetron sputtering using a Ru target and a Nb target as targets and Ar gas as a sputtering gas. One Ru target and one Nb target were each mounted on a magnetron sputtering apparatus different from the magnetron sputtering apparatus that formed the Si / Mo stacked layer, and the arrangement of the substrate and each target was an offset arrangement, and it was formed while rotating the substrate. The movement of the substrate on which the Si / Mo stacked layer was formed from the magnetron sputtering apparatus that formed the Si / Mo stacked layer to the magnetron sputtering apparatus that formed the protective layer was carried out under vacuum via a transfer chamber communicating with both sputtering chambers. Ar gas was flowed into the sputtering chamber, and the Ru target and the Nb target were simultaneously discharged to form a RuNb mixed layer with a set thickness of 2.0 nm as a protective layer.

[0082] When the cross-section of the obtained multilayer reflective film was observed with a transmission electron microscope (TEM), on the upper part of the multilayer reflective film, in order from the surface side (the side away from the substrate), a RuNb mixed layer with a thickness of 2.0 nm, a Mo layer with a thickness of 1.0 nm, an interdiffusion layer in which Si and Mo with a thickness of 1.5 nm were mixed, a Si layer with a thickness of 3.5 nm, an interdiffusion layer in which Si and Mo with a thickness of 0.5 nm were mixed, and a Mo layer with a thickness of 2.5 nm were observed, and no interdiffusion layer was formed between the RuNb mixed layer and the Mo layer. Further, for the multilayer reflective film obtained by the same method, heat treatment was carried out at 200 °C for 10 minutes in an air atmosphere, and when the cross-section of the multilayer reflective film was observed in the same manner, on the upper part of the multilayer reflective film, in order from the surface side (the side away from the substrate), a RuNb mixed layer with a thickness of 2 nm, a SiO layer with a thickness of 2 nm, an interdiffusion layer in which Si and Mo with a thickness of 1.0 nm were mixed, a Si layer with a thickness of 1.5 nm, an interdiffusion layer in which Si and Mo with a thickness of 0.5 nm were mixed, a Mo layer with a thickness of 2.5 nm, and an interdiffusion layer in which Si and Mo with a thickness of 1.5 nm were mixed were observed, and a SiO layer formed by the reaction of oxygen in the air passing through the RuNb mixed layer and reacting with the Si layer was formed. Further, when the peak reflectance at an incident angle of 6° of EUV light in the wavelength range of 13.4 to 13.6 nm was measured before and after the heat treatment, it was 64% before the heat treatment and 62% after the heat treatment, and both were low reflectances of less than 65%.

[0083] [Comparative Example 3] A multilayer reflective film composed of a Si / Mo laminated portion and a protective layer containing Ru was formed on a substrate made of a low thermal expansion material with a thermal expansion coefficient in the range of ±5.0×10 -9 / °C, the surface roughness of the main surface being 0.1 nm or less in RMS value and the flatness of the main surface being 100 nm in TIR value.

[0084] The Si / Mo stacked layer was formed by magnetron sputtering using a Si target and a Mo target as targets and Ar gas as a sputtering gas. One Si target and one Mo target were each mounted on a magnetron sputtering apparatus, and the substrate and each target were arranged in an offset configuration, and the substrate was rotated during formation. First, Ar gas was flowed into the sputtering chamber, and only the Si target was discharged to form a Si layer with a set thickness of 4.0 nm. Next, Ar gas was flowed into the sputtering chamber, and only the Mo target was discharged to form a Mo layer with a set thickness of 3.0 nm. The formation of these Si layer and Mo layer was defined as one cycle, and the formation of these two layers was repeated 40 cycles in total. Thereafter, Ar gas was flowed into the sputtering chamber, and only the Si target was discharged to form a Si layer with a set thickness of 3.0 nm. Next, Ar gas was flowed into the sputtering chamber, and only the Mo target was discharged to form a Mo layer with a set thickness of 1.0 nm to obtain the Si / Mo stacked layer.

[0085] The protective layer was formed by magnetron sputtering using a Ru target as a target and Ar gas as a sputtering gas. One Ru target was mounted on a magnetron sputtering apparatus different from the magnetron sputtering apparatus that formed the Si / Mo stacked layer, and the substrate and the target were arranged to face each other, and the substrate was rotated during formation. The movement of the substrate on which the Si / Mo stacked layer was formed from the magnetron sputtering apparatus that formed the Si / Mo stacked layer to the magnetron sputtering apparatus that formed the protective layer was carried out under vacuum via a transfer chamber communicating with both sputtering chambers. Ar gas was flowed into the sputtering chamber, and the Ru target was discharged to form a Ru layer with a set thickness of 2.5 nm as the protective layer.

[0086] When the cross-section of the obtained multilayer reflective film was observed with a transmission electron microscope (TEM), on the upper part of the multilayer reflective film, in order from the surface side (the side away from the substrate), a Ru layer with a thickness of 2.5 nm, an interdiffusion layer in which Si and Mo with a thickness of 1.2 nm were mixed, a Si layer with a thickness of 2.8 nm, an interdiffusion layer in which Si and Mo with a thickness of 0.5 nm were mixed, a Mo layer with a thickness of 2.7 nm, and an interdiffusion layer in which Si and Mo with a thickness of 1.3 nm were mixed were observed. Also, for the multilayer reflective film obtained by the same method, heat treatment was carried out in an air atmosphere at 200 °C for 10 minutes, and when the cross-section of the multilayer reflective film was observed in the same manner, on the upper part of the multilayer reflective film, in order from the surface side (the side away from the substrate), a Ru layer with a thickness of 2.5 nm, an interdiffusion layer in which Si and Mo with a thickness of 1.6 nm were mixed, a Si layer with a thickness of 2.6 nm, an interdiffusion layer in which Si and Mo with a thickness of 0.5 nm were mixed, a Mo layer with a thickness of 2.6 nm, and an interdiffusion layer in which Si and Mo with a thickness of 1.6 nm were mixed were observed. Further, when the peak reflectance at an incident angle of 6° of EUV light in the wavelength range of 13.4 to 13.6 nm was measured before and after the heat treatment, it was 65% before the heat treatment and 62% after the heat treatment, and after the heat treatment, the reflectance was low, less than 65%.

Explanation of symbols

[0087] 1 Substrate 10 Substrate with multilayer reflective film for EUV mask blank 2 Multilayer reflective film 21 Si / Mo laminated part 211 Si layer 212 Mo layer 213 Layer containing Si and N 21a Interdiffusion layer composed of Si and Mo 21b Interdiffusion layer composed of Si and Ru 22 Protective layer 221 Lower layer 222 Upper layer 100 Sputtering apparatus 101, 102 Sputtering chambers 103 Conveying chamber 104 Load lock chamber

Claims

1. A substrate and a multilayer reflective film provided on the substrate, the multilayer reflective film having a Si / Mo stacked portion in which Si layers and Mo layers are alternately stacked, and on the Si / Mo stacked portion, a protective layer containing Ru formed in contact with the Si / Mo stacked portion as the uppermost layer of the multilayer reflective film, the protective layer being composed of two layers, a lower layer provided in contact with the Si / Mo stacked portion and an upper layer provided on the side farthest from the substrate, the lower layer being formed of only Ru, and the upper layer being formed of a material containing Ru and one or more metals or semimetals different from Ru, A layer containing Si and N is formed in contact with both the Si layer and the Mo layer at any one or more of the interfaces between the Si layer and the Mo layer in the Si / Mo stacked portion, The uppermost part of the multilayer reflective film is composed of, from the side away from the substrate, the protective layer, the Mo layer, the layer containing Si and N, and the Si layer, At the uppermost part of the multilayer reflective film composed of, from the side away from the substrate, the protective layer, the Mo layer, the layer containing Si and N, and the Si layer, the thickness of the protective layer is 4 nm or less, the thickness of the Mo layer is 1 nm or less, the thickness of the layer containing Si and N is 2 nm or less, and the thickness of the Si layer is 4 nm or less. A substrate with a multilayer reflective film for an EUV mask blank, characterized by the above.

2. The substrate with a multilayer reflective film for an EUV mask blank according to claim 1, characterized in that the metal different from Ru is a transition metal having a standard redox potential lower than that of Ru.

3. The substrate with a multilayer reflective film for an EUV mask blank according to claim 1 or 2, characterized in that the upper layer is formed of a material containing Ru and one or more selected from Nb, Zr, Ti, Cr, and Si.

4. wherein the upper layer contains Ru, O 2 gas, and Cl 2 The substrate with a multilayer reflective film for an EUV mask blank according to any one of claims 1 to 3, characterized in that it is formed of a material containing one or more metals or semimetals having an etching rate slower than that of Ru in dry etching using an etching gas containing Ru, O

5. The substrate with a multilayer reflective film for an EUV mask blank according to any one of claims 1 to 4, characterized in that the upper layer is formed of a material composed of Ru and one or more metals or semimetals different from Ru.

6. The substrate with a multilayer reflective film for an EUV mask blank according to any one of claims 1 to 4, characterized in that the upper layer further contains oxygen.

7. The substrate with a multilayer reflective film for an EUV mask blank according to any one of claims 1 to 4, characterized in that the upper layer is formed of a material composed of Ru and one or more selected from Nb, Zr, and Cr.

8. In the Si / Mo laminated portion, from the substrate side, a three-layer laminated structure unit composed of a Si layer, a layer containing Si and N formed in contact with the Si layer, and a Mo layer formed in contact with the layer containing Si and N, or from the substrate side, a three-layer laminated structure unit composed of a Mo layer, a layer containing Si and N formed in contact with the Mo layer, and a Si layer formed in contact with the layer containing Si and N. The EUV mask blank substrate with a multilayer reflective film according to any one of claims 1 to 7, characterized in that 30 or more such three-layer laminated structure units are included.

9. In the Si / Mo laminated portion, from the substrate side, a four-layer laminated structure unit composed of a Si layer, a layer containing Si and N formed in contact with the Si layer, a Mo layer formed in contact with the layer containing Si and N, and a layer containing Si and N formed in contact with the Mo layer. The EUV mask blank substrate with a multilayer reflective film according to any one of claims 1 to 7, characterized in that 30 or more such four-layer laminated structure units are included.

10. The EUV mask blank substrate with a multilayer reflective film according to any one of claims 1 to 9, characterized in that the peak reflectivity of the multilayer reflective film at an incident angle of 6° of EUV light in the wavelength range of 13.4 to 13.6 nm is 65% or more.

11. A method for manufacturing an EUV mask blank substrate with a multilayer reflective film according to any one of claims 1 to 10, (A) A step of forming the Si / Mo laminated portion by sputtering is included, and the sputtering is carried out using one or more Mo targets and one or more Si targets, applying power to the Mo target and the Si target separately, with the arrangement of the substrate and each target being an offset arrangement, having no member for shielding between each target and the substrate, being able to rotate the substrate along the main surface, and being able to introduce a nitrogen-containing gas The method for manufacturing an EUV mask blank substrate with a multilayer reflective film is characterized by being carried out in a magnetron sputtering apparatus equipped with a chamber.

12. A method for manufacturing an EUV mask blank substrate with a multilayer reflective film according to any one of claims 1 to 10, including (B) a step of forming the protective layer by sputtering and the sputtering is carried out One or more Ru targets and one or more targets containing one or more metals or metalloids different from Ru can be mounted respectively. Power can be applied separately to the Ru target and the target containing one or more metals or metalloids different from Ru. The arrangement of the substrate and each target is an offset arrangement. It does not have a member that shields between each target and the substrate. The substrate can be rotated along the main surface, and an oxygen-containing gas can be introduced. A method for manufacturing a substrate with a multilayer reflective film for an EUV mask blank, which is carried out in a magnetron sputtering apparatus provided with a chamber.

13. An EUV mask blank, characterized in that on the multilayer reflective film of the substrate with a multilayer reflective film for an EUV mask blank according to any one of Claims 1 to 10, in contact with the protective layer, there is an absorber film containing Ta or Cr.

14. An EUV mask blank, characterized in that on the multilayer reflective film of the substrate with a multilayer reflective film for an EUV mask blank according to any one of Claims 1 to 10, in contact with the protective layer, there is an absorber film containing Ta and not containing Cr, and on the absorber film, there is a hard mask film containing Cr and functioning as an etching mask when dry-etching the absorber film.

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