Reflective photomask blanks and reflective photomasks

Abstract

To provide a reflective photomask blank with excellent resistance to hydrogen radicals. [Solution] A reflective photomask blank and a reflective photomask made using the same, comprising a substrate, a reflective layer disposed on the substrate that reflects EUV light, a protective layer disposed on the reflective layer that protects the reflective layer, and an absorbing layer disposed on the protective layer that absorbs EUV light, wherein the absorbing layer comprises a first absorbing layer and a second absorbing layer, and each of the first absorbing layer and the second absorbing layer contains 40 at% or more of a metal element having a positive hydrogen dissolution energy Es.

Description

Technical Field

[0001] The present disclosure relates to a reflective photomask blank and a reflective photomask.

Background Art

[0002] In the manufacturing process of semiconductor devices, along with the miniaturization of semiconductor devices, demands for the miniaturization of photolithography technology are increasing. The minimum resolution dimension of a transferred pattern in photolithography greatly depends on the wavelength of the exposure light source, and the shorter the wavelength is, the smaller the minimum resolution dimension can be. For this reason, the exposure light source has been replaced from the conventional ArF excimer laser light with a wavelength of 193 nm to light in the EUV (Extreme Ultra Violet) region with a wavelength of 13.5 nm. Light in the EUV region is absorbed by most materials at a high rate, so in lithography using EUV light, a reflective photomask is used as a photomask for EUV exposure (EUV mask). As a reflective photomask blank that reduces errors caused by charging when measuring pattern dimensions using a CD-SEM, for example, Patent Document 1 discloses a reflective photomask blank obtained by forming a reflective layer composed of a multilayer film in which Mo (molybdenum) layers and Si (silicon) layers are alternately laminated on a glass substrate, forming a light absorption layer mainly containing Ta (tantalum) thereon, and forming a pattern in this light absorption layer.

[0003] Further, in EUV exposure apparatuses, the LPP (Laser Produced Plasma) method is mainly adopted for generating EUV light. The LPP method is a method in which plasma is generated by irradiating a tin (Sn) droplet with a CO2 laser, and EUV light is condensed by a multilayer reflective mirror. In EUV exposure apparatuses, cleaning with hydrogen radicals is performed to prevent contamination inside the chamber caused by scattered tin (Sn) debris (fragments). That is, since reflective photomasks are exposed to a hydrogen radical environment, it has been necessary to form them using materials having resistance to hydrogen radicals. Furthermore, as mentioned above, EUV lithography cannot use refractive optics that utilize light transmission, so the optical components of the exposure machine are reflective (mirror) rather than lenses. This presents a problem in that the incident and reflected light to the reflective photomask (EUV mask) cannot be designed to be coaxial. Typically, EUV lithography employs a method in which the optical axis is tilted 6 degrees from the perpendicular direction of the EUV mask, and the reflected light, which is reflected at a -6 degree angle, is guided to the semiconductor substrate.

[0004] As a reflective photomask blank and reflective photomask having high transferability (especially resolution) and sufficient hydrogen radical resistance, for example, Patent Document 2 discloses a reflective photomask blank for making a reflective photomask for pattern transfer using extreme ultraviolet light as a light source, comprising a substrate, a reflective layer including a multilayer film formed on the substrate, and an absorption layer formed on the reflective layer, wherein the absorption layer is a laminated structure in which an absorption control film and a phase control film are laminated, the absorption layer has a phase difference in the range of 188 degrees to 268 degrees, the total thickness of the absorption layer is 60 nm or less, and the absorption control film is made of a material containing a total of 70 atomic percent or more of tin (Sn) and oxygen (O), and tantalum (Ta) in the range of 5 atomic percent to 20 atomic percent. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Patent No. 5418293 [Patent Document 2] Japanese Patent Publication No. 2024-069789 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] In conventional reflective photomasks, tantalum (Ta) has been used as the main material due to its wide process margin in terms of etchability and cleaning resistance. However, there have been concerns that reflective photomasks equipped with conventional tantalum (Ta) absorption layers may experience delamination between the absorption layer and the protective layer due to hydrogen penetration and accumulation within the absorption layer after prolonged exposure to EUV. In the reflective photomask disclosed in Patent Document 2 mentioned above, there is a need for further improvement in hydrogen radical resistance and the development of a reflective photomask that is less prone to film peeling even after long-term exposure. This disclosure has been made in view of the above-mentioned problems, and one embodiment of this disclosure aims to solve the problem of providing a reflective photomask blank that can obtain a reflective photomask with excellent hydrogen radical resistance. Another embodiment of this disclosure aims to solve the problem of providing a reflective photomask with excellent hydrogen radical resistance. [Means for solving the problem]

[0007] As a result of diligent research, the inventors have discovered that using a metal element with a positive hydrogen dissolution energy Es as the absorption layer improves the hydrogen radical resistance of the resulting reflective photomask, leading to this disclosure. The means for solving the above problems include the following embodiments.

[0008] <1> circuit board and A reflective layer that reflects EUV light is placed on the substrate, A protective layer disposed on the reflective layer to protect the reflective layer, The protective layer comprises an absorbing layer that absorbs EUV light, The absorbent layer comprises a first absorbent layer and a second absorbent layer. A reflective photomask blank in which the first absorption layer and the second absorption layer each contain 40 at% or more of a metallic element having a positive hydrogen dissolution energy Es. <2> The metallic element having a positive hydrogen dissolution energy Es is at least one metallic element selected from the following first group of materials and the following second group of materials. <1> Reflective photomask blank as described; First group of materials: Molybdenum (Mo), tungsten (W), and chromium (Cr); The second group of materials: platinum (Pt), ruthenium (Ru), and iridium (Ir). <3> The first absorption layer comprises at least one metal element selected from the first group of materials, and the second absorption layer comprises at least one metal element selected from the second group of materials. <1> or <2> A reflective photomask blank as described above. <4> The first absorption layer comprises at least one metal element selected from the second group of materials, and the second absorption layer comprises at least one metal element selected from the first group of materials. <1> ~ <3> A reflective photomask blank as described in one of the following. <5> circuit board and A reflective layer that reflects EUV light is placed on the substrate, A protective layer placed on the reflective layer to protect the reflective layer, The protective layer comprises an absorbing layer that absorbs EUV light, The absorption layer is a reflective photomask blank containing 40 at% or more of a metallic element having a positive hydrogen dissolution energy Es. <6> The metal element having a positive hydrogen dissolution energy Es is at least one metal element selected from the following first group of materials or the following second group of materials. <5> Reflective photomask blank as described; First group of materials: Molybdenum (Mo), tungsten (W), and chromium (Cr); The second group of materials: platinum (Pt), ruthenium (Ru), and iridium (Ir). <7> The metal element having a positive hydrogen dissolution energy Es is at least one metal element selected from the first material group and the second material group. <5> or <6> A reflective photomask blank as described above. <8> circuit board and a reflective layer disposed on said substrate that reflects EUV light; a protective layer disposed on said reflective layer that protects the reflective layer; a buffer layer disposed on said protective layer; and an absorption layer disposed on said buffer layer that absorbs EUV light, wherein said absorption layer contains 40 at% or more of a metal element having a positive hydrogen dissolution energy Es; and this is a reflective photomask blank. <9> The reflective photomask blank according to <8>, wherein the metal element having a positive hydrogen dissolution energy Es is at least one metal element selected from the following first material group or second material group; First material group: molybdenum (Mo), tungsten (W), and chromium (Cr); Second material group: platinum (Pt), ruthenium (Ru), and iridium (Ir). <10> The reflective photomask blank according to <8> or <9>, wherein the metal element having a positive hydrogen dissolution energy Es is at least one metal element selected from said first material group and said second material group. <11> The reflective photomask blank according to any one of <8> to <10>, wherein said buffer layer contains tantalum (Ta) or chromium (Cr). <12> A reflective photomask produced using the reflective photomask blank according to any one of <1> to <11>. Effects of the Invention

[0009] According to an embodiment of the present disclosure, a reflective photomask blank capable of obtaining a reflective photomask excellent in hydrogen radical resistance can be provided. Further, according to an embodiment of the present disclosure, a reflective photomask excellent in hydrogen radical resistance can be provided. Brief Description of Drawings

[0010] [Figure 1] FIG. 1 is a cross-sectional view showing an example of the reflective photomask blank according to the first embodiment of the present disclosure. [Figure 2] Fig. 2 is a cross-sectional view showing an example of a reflective photomask blank according to a second embodiment of the present disclosure. [Figure 3] Fig. 3 is a cross-sectional view showing an example of a reflective photomask blank according to a third embodiment of the present disclosure. [Figure 4] Fig. 4 is a cross-sectional view showing an example of a conventional reflective photomask and a reflective photomask according to a second embodiment of the present disclosure. [Figure 5] Fig. 5 is a cross-sectional view showing an example of a reflective photomask according to a first embodiment of the present disclosure. [Figure 6] Fig. 6 is a cross-sectional view showing an example of a reflective photomask according to a third embodiment of the present disclosure. [Figure 7] Fig. 7 is a cross-sectional view showing the manufacturing process of the reflective photomask used in an example of the present disclosure. [Figure 8] Fig. 8 is a cross-sectional view showing the manufacturing process of the reflective photomask used in an example of the present disclosure. [Figure 9] Fig. 9 is a cross-sectional view showing the manufacturing process of the reflective photomask used in an example of the present disclosure. [Figure 10] Fig. 10 is a plan view showing an example of a conventional reflective photomask. [Figure 11] Fig. 11 is a schematic diagram showing the change in potential energy from when hydrogen adsorbs on a metal surface to when it penetrates into the interior of the metal. MODE FOR CARRYING OUT THE INVENTION

[0011] Hereinafter, embodiments of the present disclosure will be described. Descriptions of constituent features below may be made based on representative embodiments of the present disclosure, but the present disclosure is not limited to such embodiments. Here, the members shown in each drawing are conceptual, and the relative relationships such as the relationship between thickness and planar dimension, the ratio of thicknesses of respective layers, and the sizes between members are not limited thereto. In addition, members or portions having similar functions are given the same reference numerals throughout all the drawings, and the description thereof may be omitted. Furthermore, the embodiments shown below illustrate configurations for realizing the technical concept of this disclosure, and the technical concept of this disclosure is not limited to the materials, shapes, structures, etc., of the components described below. The technical concept of this disclosure can be modified in various ways, such as by referring to prior art, as long as it does not exceed the technical scope defined by this disclosure.

[0012] (Reflective photomask blank according to the first embodiment) A reflective photomask blank according to the first embodiment of this disclosure will be described with reference to the drawings. The reflective photomask blank according to this disclosure comprises a substrate, a reflective layer disposed on the substrate that reflects EUV light, a protective layer disposed on the reflective layer that protects the reflective layer, and an absorbing layer disposed on the protective layer that absorbs EUV light, wherein the absorbing layer comprises a first absorbing layer and a second absorbing layer, and each of the first absorbing layer and the second absorbing layer contains 40 at% or more of a metallic element having a positive hydrogen dissolution energy Es.

[0013] (Conventional reflective photomask configuration) Before describing the configuration of the reflective photomask blank according to the first embodiment of this disclosure, the basic configuration of a conventional reflective photomask will be described using Figures 4 and 10. Figure 4 is a cross-sectional view showing an example of a conventional reflective photomask (200a). As shown in Figure 4, in the conventional reflective photomask (200a), a reflective layer (13), a protective layer (12), and an absorption pattern layer (101) are stacked in this order on one side of the substrate (14). The absorption pattern layer (101) is formed by patterning the absorption layer (10), which will be described later. In addition, a conductive film (15) may be formed on the other side of the substrate (14) of the conventional reflective photomask (200a).

[0014] Figure 10 is an example of a plan view of a conventional reflective photomask (200a). A single reflective photomask (200a) has one or more main pattern regions (20) formed on it for forming semiconductor integrated circuit patterns on a silicon wafer, and each main pattern region (20) is demarcated by a peripheral region (21) that does not contribute to the formation of the semiconductor integrated circuit pattern. The peripheral region (21) is covered with an absorption layer (10) to demarcate chips on the silicon wafer, except for some accessory patterns, and the peripheral region (21) does not contribute to the transfer. Furthermore, a light-shielding band (22) is formed at the outermost edge of the peripheral region (21) at the edge of the desired exposure region.

[0015] A reflective photomask blank (100a) and a reflective photomask (200b) according to the first embodiment of this disclosure will be described with reference to Figures 1 and 5. Figure 1 is a cross-sectional view showing an example of a reflective photomask blank (100a) according to the first embodiment of the present disclosure. In the reflective photomask blank (100a) according to the first embodiment of the present disclosure, a reflective layer (13), a protective layer (12), and an absorbent layer (10) are laminated in contact with one side of a substrate (14) in that order. The absorbent layer (10) is laminated on the protective layer (12) in the order of a first absorbent layer (10a) and a second absorbent layer (10b). The absorbent layer (10) comprises at least one pair of the first absorbent layer (10a) and the second absorbent layer (10b). Furthermore, in the reflective photomask blank (100a) according to the first embodiment, a conductive film (15) may be formed on the other surface of the substrate (14). Figure 5 is a cross-sectional view showing an example of a reflective photomask (200b) according to the first embodiment described above. The reflective photomask (200b) is obtained by patterning the absorption layer (10) of the reflective photomask blank (100a) using a method described later. The following describes in detail each layer of the reflective photomask blank (100a).

[0016] (substrate) The substrate (14) is a layer that serves as the base material for the reflective photomask blank (100a). There are no particular restrictions on the substrate (14), and for example, a flat Si substrate or a synthetic quartz substrate can be used. In addition, a titanium-doped low thermal expansion glass can be used for the substrate (14), but this disclosure is not limited to these materials as long as the material has a low coefficient of thermal expansion.

[0017] (Conductive film) The reflective photomask blank (100a) may have a conductive film (15) formed on the side of the substrate (14) that does not have a reflective layer (13). The conductive film (15) is a film used to fix the reflective photomask (200b) when it is placed in the exposure machine using the principle of an electrostatic chuck. The conductive film (15) is generally made of CrN, but any material made of a conductive material is acceptable.

[0018] (reflective layer) The reflective layer (13) is a reflective layer placed on the substrate (14) that reflects EUV light. The reflective layer (13) is a layer provided in the reflective photomask blank (100a) to reflect EUV light (extreme ultraviolet light), which is the exposure light. The reflective layer (13) is preferably a multilayer structure (i.e., composed of multiple reflective films) made up of materials with significantly different refractive indices for EUV light. The reflective layer (13) may be a layer in which layers of combinations of elements such as Mo (molybdenum) and Si (silicon), or Mo (molybdenum) and Be (beryllium) are repeatedly stacked for about 40 periods.

[0019] (protective layer) The protective layer (12) is a layer that protects the reflective layer (13) and is placed on the reflective layer (13). The protective layer (12) functions as an etching stopper to prevent damage to the reflective layer (13) when the absorption pattern layer (101) is formed by etching. Preferably, the protective layer (12) is made of a material that is resistant to dry etching performed when the pattern of the absorption layer (10) is formed. Examples of materials for the protective layer include ruthenium (Ru), zirconium (Zr), rhodium (Rh), and niobium (Nb).

[0020] (Absorption layer) The absorption layer (10) is a layer placed on the protective layer (12). The absorption layer (10) is a layer that absorbs EUV light, which is the exposure light, in the reflective photomask blank (100a). Furthermore, the absorption layer (10) is a layer on which an absorption pattern layer (101), which is a fine pattern for transferring the pattern on the photomask to the photoresist on the silicon wafer, is formed when the portion of the absorption layer (10) that has been removed reflects EUV light. The absorption layer (10) is preferably a film thickness that provides sufficient light shielding in order to absorb EUV light.

[0021] Figure 5 is a cross-sectional view showing an example of a reflective photomask (200b) fabricated using a reflective photomask blank according to the first embodiment. By removing a portion of the absorption layer (10) in the reflective photomask blank (100a) (i.e., patterning the absorption layer (10)), a reflective photomask (200b) with an absorption pattern layer (101) formed on it is obtained, as shown in Figure 5.

[0022] (First absorption layer and second absorption layer) The absorption layer (10) according to the first embodiment of the present disclosure comprises a first absorption layer (10a) and a second absorption layer (10b), wherein the first absorption layer (10a) and the second absorption layer (10b) each contain 40 at% or more of a metallic element having a positive hydrogen dissolution energy Es. The content (at%: atomic percent) of metal elements whose hydrogen dissolution energy Es is positive is the ratio of the number of atoms of metal elements whose hydrogen dissolution energy Es is positive to the total number of atoms contained in the first absorption layer (10a) or the second absorption layer (10b). The hydrogen dissolution energy Es is the energy required for hydrogen to dissolve in a metal, and it is a value that indicates the affinity between hydrogen and the metal. The hydrogen dissolution energy Es can be calculated using an Arrhenius plot obtained by electrochemical permeation, etc., but in this disclosure, the value described in Y. Fukai, The Metal-Hydrogen System, Springer, (1993) was used.

[0023] From the viewpoint of excellent resistance to hydrogen radicals, the content of the above-mentioned metal elements in the first absorption layer (10a) and the second absorption layer (10b) is preferably 40 to 100 at%. The content of metal elements having a positive hydrogen dissolution energy Es is determined by the measurement method described in the examples below. The metal element having a positive hydrogen dissolution energy Es may be a single element or two or more elements may be used in combination.

[0024] If the absorption layer (10) contains two or more metal elements whose hydrogen dissolution energy Es is positive, the content ratio of the metal elements in the first absorption layer (10a) and the second absorption layer (10b) may be different, provided that the total content of the metal elements with positive hydrogen dissolution energy Es in the absorption layer (10) is 40 at% or more. Furthermore, the value of the hydrogen dissolution energy Es mentioned above is not particularly limited as long as it has a positive value.

[0025] The mechanism by which the hydrogen radical resistance of the resulting reflective photomask is improved by using a metal element with a positive hydrogen dissolution energy Es as the absorption layer (first absorption layer (10a) and second absorption layer (10b)) in the reflective photomask blank according to this disclosure is not clear, but it can be explained based on the schematic diagram shown in Figure 11. As shown in Figure 11, in the EUV exposure apparatus, after hydrogen is adsorbed onto the metal surface used in the absorption layer (10), it receives energy greater than the hydrogen dissolution energy Es inherent to the metal element, causing the hydrogen atoms to dissociate into a radical state or the like, penetrate into the metal, and form a solid solution. If the hydrogen dissolution energy Es of the metal element is negative, the hydrogen dissolution energy Es is lower than the adsorption energy of the hydrogen atoms, allowing hydrogen to easily penetrate into the metal. Also, if the hydrogen dissolution energy Es of the metal element is positive, hydrogen needs to receive energy from the outside in order to penetrate into the metal. We hypothesize that hydrogen that penetrates the metal accumulates in traps such as metal interfaces and lattice defects, and that when exposed to prolonged EUV exposure, film delamination occurs in the photomask. The reflective photomask blank according to the embodiment of this disclosure includes an absorption layer (10) containing a metal element having a positive hydrogen dissolution energy Es. Because the penetration of hydrogen into the metal forming the absorption layer (10) is suppressed, the reflective photomask obtained from this reflective photomask blank has excellent hydrogen radical resistance. Conventional absorption layers (10) used in reflective photomasks primarily use tantalum (Ta). Since the hydrogen dissolution energy Es of tantalum (Ta) is -0.4 eV / atom, which is a negative value, tantalum (Ta) is a material that allows hydrogen to easily penetrate into the metal interior.

[0026] Examples of metallic elements with a positive hydrogen dissolution energy Es include silver (Ag), aluminum (Al), gold (Au), cobalt (Co), chromium (Cr), copper (Cu), iron (Fe), iridium (Ir), molybdenum (Mo), nickel (Ni), platinum (Pt), rhodium (Rh), ruthenium (Ru), and tungsten (W). Among these, chromium (Cr), iridium (Ir), molybdenum (Mo), platinum (Pt), ruthenium (Ru), and tungsten (W) are preferred as metallic elements with a positive hydrogen dissolution energy Es, from the viewpoint of widening the process margin in the fabrication of reflective photomasks (i.e., having excellent processability and cleaning resistance).

[0027] It is more preferable that the metal element having a positive hydrogen dissolution energy Es contains at least one metal element selected from the first group of materials, molybdenum (Mo), tungsten (W), and chromium (Cr), in either the first absorption layer (10a) or the second absorption layer (10b), and the other absorption layer contains at least one metal element selected from the second group of materials, platinum (Pt), ruthenium (Ru), and iridium (Ir). When the absorption layer (10) contains a metal element from the first material group, etching becomes easier. Furthermore, when the absorption layer (10) contains a metal element from the second material group, it exhibits superior cleaning resistance.

[0028] Furthermore, the absorption layer (10) may also contain nonmetallic elements such as oxygen (O), nitrogen (N), and boron (B), in addition to the metal elements having a positive Es value. The content of nonmetallic elements in the absorption layer (10) is preferably 5 to 50 at%, and more preferably 5 to 30 at%, relative to the total number of atoms in the absorption layer.

[0029] If the absorption layer (10) contains 40 at% or more of metal elements having a positive hydrogen dissolution energy Es, the absorption layer (10) may further contain metal elements having a negative hydrogen dissolution energy Es. Examples of metallic elements with negative hydrogen dissolution energy Es include tantalum (Ta), niobium (Nb), and titanium (Ti). The content of metal elements having a negative hydrogen dissolution energy Es in the absorption layer (10) is preferably 5 to 60 at%, and more preferably 5 to 20 at%, relative to the total number of atoms in the absorption layer.

[0030] The film thickness of the first absorption layer (10a) and the second absorption layer (10b) is preferably 10 to 50 nm, and more preferably 20 to 30 nm. The film density of the first absorption layer (10a) and the second absorption layer (10b) is preferably 4.0 g / cm³. 3 That's all. The film thickness and film density of the first absorption layer (10a) and the second absorption layer (10b) may be the same or different.

[0031] (Hard mask layer) The reflective photomask blank (100a) according to the first embodiment may further comprise a hard mask layer on top of the absorption layer (10). The material used to constitute the hard mask layer is preferably one that is resistant to dry etching, such as chromium (Cr) or silicon (Si). By using a material that is resistant to dry etching for the hard mask layer, the process margin when patterning the absorption layer (10) can be widened. The thickness of the hard mask layer is preferably 2 to 30 nm, and more preferably 5 to 10 nm or less. Furthermore, the hard mask layer is ultimately peeled off during the manufacturing process of the reflective photomask (200a), and therefore does not remain on the reflective photomask (200a).

[0032] The reflective photomask blank relating to this disclosure may further include layers other than the reflective layer, protective layer, absorption layer, hard mask layer, and buffer layer described later (hereinafter sometimes referred to as "other layers") as needed.

[0033] (Light-blocking strip) The reflective photomask (200b) according to the first embodiment may have a light-shielding band (22) pattern formed thereon. In the formation of semiconductor integrated circuit patterns, multiple exposures are typically performed using a single reflective photomask when exposing a silicon wafer. The reflectivity of EUV light on the absorption layer (10) is approximately 0.5 to 2%. Therefore, from the viewpoint of preventing photosensitivity of the outer edge of the chip due to multiple exposures, it is preferable to provide a light-shielding band (22) with higher EUV light-shielding capabilities than the normal absorption layer (10) on the outer edge of the chip on the mask for mass production of semiconductor integrated circuits by EUV lithography. The light-shielding band (22) in the reflective photomask (200b) is formed by patterning the reflective layer (13).

[0034] The photomask blank relating to this disclosure can be obtained by forming each of the above layers using a known film deposition method. Examples of film deposition methods include CVD (chemical vapor deposition) and sputtering. Among these, sputtering is preferred because it offers good controllability and makes it easy to form films with desired properties. Examples of sputtering methods include DC (direct current) sputtering, RF (radio frequency) sputtering, and ion beam sputtering, but ion beam sputtering is preferred.

[0035] The gas used for film deposition (sputtering) can be appropriately selected depending on the components contained in the film to be formed. Examples of gases used for sputtering include noble gases such as helium (He), neon (Ne), and argon (Ar); and nitrogen oxide gases such as oxygen (O2), nitrogen (N2), nitric oxide (NO), and nitrogen dioxide (NO2). These gases can be used in appropriate combinations. Furthermore, the gas flow rate during film deposition can be set appropriately to achieve the desired composition, and is usually between 0.1 and 100 sccm. The pressure during film formation should be set appropriately considering film stress, chemical resistance, and washing resistance, and is usually 0.01 Pa or higher, preferably 0.03 Pa or higher, and usually 1 Pa or lower, preferably 0.3 Pa or lower.

[0036] In the manufacturing of the reflective photomask blank according to this disclosure, a cleaning process may be performed to remove particles present on the surface of the substrate or absorption layer. The cleaning can be performed using either or both ultrapure water and functional water, which is ultrapure water containing ozone gas, hydrogen gas, etc. Alternatively, cleaning may be performed with water containing a surfactant, followed by further cleaning with either or both ultrapure water and functional water. The cleaning can be performed while irradiating with ultrasound as needed, and UV light irradiation may also be combined with the cleaning.

[0037] (Reflective photomask blank according to the second embodiment) A reflective photomask blank according to a second embodiment of the present disclosure comprises a substrate, a reflective layer disposed on the substrate that reflects EUV light, a protective layer disposed on the reflective layer, and an absorbing layer disposed on the protective layer that absorbs EUV light, wherein the absorbing layer contains 40 at% or more of a metallic element having a positive hydrogen dissolution energy Es.

[0038] The configuration of the reflective photomask blank (100b) according to the second embodiment of this disclosure will be explained with reference to Figure 2. Figure 2 is a cross-sectional view showing an example of a reflective photomask blank (100b) according to a second embodiment of the present disclosure. In the reflective photomask blank (100b) according to the second embodiment of the present disclosure, a reflective layer (13), a protective layer (12), and an absorption layer (10) are laminated in this order on one side of the substrate (14). A conductive film (15) may also be formed on the other side of the substrate (14).

[0039] In the reflective photomask blank according to the second embodiment of this disclosure, the substrate (14), reflective layer (13), protective layer (12), absorption layer (10), and conductive film (15) are the same as those in the reflective photomask blank according to the first embodiment described above, and the preferred embodiments are also the same.

[0040] The absorption layer (10) contains 40 at% or more of a metal element having a positive hydrogen dissolution energy Es. The absorption layer (10) is preferably formed as a single layer. The content of metal elements having a positive hydrogen dissolution energy Es is preferably 40 to 100 at%. The content of metal elements having a positive hydrogen dissolution energy Es is determined by the measurement method described in the examples below.

[0041] The metal element having a positive hydrogen dissolution energy Es may be a single element or two or more elements may be used in combination. If the absorption layer (10) contains two or more metal elements having a positive hydrogen dissolution energy Es, it is sufficient that the total content of metal elements having a positive hydrogen dissolution energy Es in the absorption layer (10) is 40 at% or more, and the content ratios of the above metal elements in the absorption layer (10) may be different.

[0042] From the viewpoint of widening the process margin in the fabrication of a reflective photomask, preferred metal elements with positive hydrogen dissolution energy Es in the absorption layer (10) are chromium (Cr), iridium (Ir), molybdenum (Mo), platinum (Pt), ruthenium (Ru), and tungsten (W). Furthermore, it is more preferable that the metallic element in the absorption layer (10) having a positive hydrogen dissolution energy Es is at least one metallic element selected from the first group of materials, which consists of molybdenum (Mo), tungsten (W), and chromium (Cr), or the second group of materials, which consists of platinum (Pt), ruthenium (Ru), and iridium (Ir). If the absorption layer (10) contains a metal element from the first material group, etching becomes easier. Furthermore, if the absorption layer (10) contains a metal element from the second material group, it exhibits superior cleaning resistance.

[0043] If the absorption layer (10) contains 40 at% or more of metal elements having a positive hydrogen dissolution energy Es, the absorption layer (10) may further contain metal elements having a negative hydrogen dissolution energy Es. The metal elements having a negative hydrogen dissolution energy Es are the same as the metal elements having a negative hydrogen dissolution energy Es in the reflective photomask blank according to the first embodiment described above, and the preferred embodiment is also the same.

[0044] The thickness of the absorption layer (10) is preferably 30 to 70 nm, and more preferably 40 to 60 nm. The film density of the absorption layer (10) is preferably 4.0 g / cm³. 3 That's all.

[0045] The reflective photomask blank according to the second embodiment may further include a hard mask layer on top of the absorption layer (10). The hard mask layer is the same as the hard mask layer in the reflective photomask blank according to the first embodiment described above, and the preferred embodiment is the same.

[0046] (Light-blocking strip) The reflective photomask (200b) according to the second embodiment may have a light-shielding band (22) pattern formed thereon. The light-shielding band (22) is the same as the light-shielding band (22) in the reflective photomask blank according to the first embodiment described above, and the preferred embodiment is the same.

[0047] (Reflective photomask blank according to the third embodiment) A reflective photomask blank according to a third embodiment of the present disclosure comprises a substrate, a reflective layer disposed on the substrate that reflects EUV light, a protective layer disposed on the reflective layer, a buffer layer disposed on the protective layer, and an absorbing layer disposed on the buffer layer that absorbs EUV light, wherein the absorbing layer contains 40 at% or more of a metallic element having a positive hydrogen dissolution energy Es. A reflective photomask blank (100c) according to the third embodiment of this disclosure will be described with reference to Figure 3. Figure 3 is a cross-sectional view illustrating an example configuration of a reflective photomask blank (100c) according to a third embodiment of the present disclosure. In the reflective photomask blank (100c) according to the third embodiment of the present disclosure, a reflective layer (13), a protective layer (12), a buffer layer (11), and an absorption layer (10) are laminated in this order on one side of the substrate (14). A conductive film (15) may also be formed on the other side of the substrate (14).

[0048] In the third embodiment of the reflective photomask blank, the substrate (14), reflective layer (13), protective layer (12), absorption layer (10), and conductive film (15) are the same as those in the first embodiment of the reflective photomask blank described above, and the preferred embodiments are also the same.

[0049] <buffer layer> The buffer layer (11) is a film that protects the protective layer (12) and the reflective film (13) when forming the absorption layer pattern using dry etching or the like in the photomask manufacturing process. For example, if the etching time is long when patterning the absorption layer (10), the protective layer (12) may become thinner than the desired thickness due to over-etching. By placing a buffer layer (11) with a short etching time between the absorption layer (10) and the protective layer (12), it is possible to reduce damage to the protective layer (12) due to over-etching. Furthermore, damage to the protective layer (12) can be prevented by placing a buffer layer between the absorption layer (10) and the protective layer (12) that can be etched with an etching gas different from the one used for the protective layer (11).

[0050] The buffer layer (11) is preferably a layer containing at least one element selected from the group consisting of tantalum (Ta), chromium (Cr), and niobium (Nb), and more preferably a layer containing tantalum (Ta) or chromium (Cr). The elemental content ratios constituting the buffer layer (11) are not particularly limited and can be set appropriately considering optical, physical, and chemical properties.

[0051] There are no particular restrictions on the method for forming the buffer layer (11), and known formation methods can be used. For example, the buffer layer (11) can be fabricated by using at least one element selected from the group consisting of tantalum (Ta), chromium (Cr), and niobium (Nb) as a sputtering target, and performing sputtering in a mixed gas atmosphere of argon and oxygen while controlling the power or current value of each target.

[0052] The thickness of the buffer layer (11) is preferably 3 to 20 nm, and more preferably 3 to 10 nm.

[0053] The absorption layer (10) placed on the buffer layer (11) contains 40 at% or more of a metal element having a positive hydrogen dissolution energy Es. The content of the metal element having a positive hydrogen dissolution energy Es is preferably 40 to 100 at%. The content of metal elements whose hydrogen dissolution energy Es is positive can be determined by the measurement method described in the examples below.

[0054] The metal element having a positive hydrogen dissolution energy Es may be a single element or two or more elements may be used in combination. If the absorption layer (10) contains two or more metal elements whose hydrogen dissolution energy Es is positive, it is sufficient that the total amount of metal elements with positive hydrogen dissolution heat Es contained in the absorption layer (10) is 40 at% or more, and the ratios of the above metal elements contained in the absorption layer (10) may be different.

[0055] From the viewpoint of widening the process margin in the fabrication of a reflective photomask, preferred metal elements with positive hydrogen dissolution energy Es in the absorption layer (10) are chromium (Cr), iridium (Ir), molybdenum (Mo), platinum (Pt), ruthenium (Ru), and tungsten (W). Furthermore, it is more preferable that the absorption layer (10) includes at least one metal element selected from the first group of materials, which consists of molybdenum (Mo), tungsten (W), and chromium (Cr), or the second group of materials, which consists of platinum (Pt), ruthenium (Ru), and iridium (Ir), as the metal element having a positive hydrogen dissolution energy Es. If the absorption layer (10) contains a metal element from the first material group, etching becomes easier. Furthermore, if the absorption layer (10) contains a metal element from the second material group, it exhibits superior cleaning resistance.

[0056] If the absorption layer (10) contains 40 at% or more of metal elements having a positive hydrogen dissolution energy Es, the absorption layer (10) may further contain metal elements having a negative hydrogen dissolution energy Es. The metal elements having a negative hydrogen dissolution energy Es are the same as the metal elements having a negative hydrogen dissolution energy Es in the reflective photomask blank according to the first embodiment described above, and the preferred embodiment is also the same.

[0057] The film thickness and film density of the absorption layer (10) are the same as those of the absorption layer (10) in the reflective photomask blank according to the second embodiment described above, and the same applies to the preferred embodiment.

[0058] The reflective photomask blank according to the third embodiment may further include a hard mask layer on top of the absorption layer (10). The hard mask layer is the same as the hard mask layer in the reflective photomask blank according to the second embodiment described above, and the preferred embodiment is the same. Furthermore, the reflective photomask blank according to the third embodiment may optionally include layers other than the reflective layer, protective layer, absorption layer, buffer layer, and hard mask layer (other layers).

[0059] (Light-blocking strip) The reflective photomask (200c) according to the third embodiment may have a light-shielding band (22) pattern formed thereon. The light-shielding band (22) is the same as the light-shielding band (22) in the reflective photomask blank according to the first embodiment described above, and the preferred embodiment is the same.

[0060] (Reflective photomask) The reflective photomask relating to this disclosure is manufactured using the above-mentioned reflective photomask blank. Since the reflective photomask according to this disclosure is manufactured using the above-mentioned reflective photomask blank, it has a sufficient process margin in patterning using light of wavelengths in the extreme ultraviolet region as a light source, and also has excellent resistance to hydrogen radicals, making it possible to use it for a long period of time in a hydrogen radical environment.

[0061] The method for manufacturing the reflective photomask described herein can be explained with reference to Figures 7 to 9. For example, first, a resist film (16) is formed on the absorption layer (10) (resist film formation step). Next, the resist film (16) is patterned to form a resist pattern (resist pattern formation step). Next, the absorbance layer (10) is patterned by dry etching using the resist pattern as an etching mask to form an absorption pattern layer (101) (pattern formation step). Finally, the remaining resist pattern is removed (exfoliation step) to obtain a reflective photomask. Furthermore, if necessary, a light-shielding band (22) (not shown) can be formed on the absorption pattern layer (101).

[0062] When exposing the resist film (16) to perform patterning, there are no particular restrictions on the exposure conditions (e.g., power output, time, etc.) and development process (e.g., developer solution, development time, etc.), and these can be set appropriately according to the composition of the resist film (16), the shape of the desired resist pattern, etc. Furthermore, dry etching using a fluorine-based gas and / or a chlorine-based gas is preferred. The patterning of the absorption layer (10) in the reflective photomask according to this disclosure is not limited to dry etching, and for example, the patterning of the absorption layer (10) may be performed using atomic layer etching (ALE).

[0063] Here, the resist film (16) can be formed from a known resist material used for the fabrication of reflective photomasks. Examples of resist materials include electron beam resists used for drawing with electron beams, photoresists used for drawing with light, and chemically amplified resists. The resist material may be either a positive-type or negative-type resist. Among these, chemically amplified resists are preferred, and positive-type chemically amplified resists are more preferred. Examples of chemically amplified resists include those containing a hydroxystyrene-based resin or a (meth)acrylic acid-based resin and an acid generator, with the addition of crosslinking agents, quenchers, surfactants, etc., as needed. The resist material may be synthesized or it may be a commercially available product. Examples of commercially available positive-type chemically amplified resists include "SEBP9012" from Shin-Etsu Chemical Co., Ltd. and "XFP-355" from Fujifilm Electronic Materials Corporation.

[0064] The thickness of the resist film (16) can be appropriately set to obtain a photomask pattern with a good shape. The thickness of the resist film (16) is preferably 50 nm or more, more preferably 70 nm or more, preferably 200 nm or less, and more preferably 150 nm or less.

[0065] There are no particular restrictions on the method for forming the resist film (16), and known formation methods can be used. For example, spin coating is preferred. [Examples]

[0066] The following will provide a detailed explanation based on examples, but this disclosure is not limited to these examples.

[0067] (Example 1) <Fabrication of reflective photomask blank (100a)> First, as shown in Figure 1, a reflective layer (13) was formed by stacking 40 laminated films of silicon (Si) and molybdenum (Mo) in pairs on a synthetic quartz substrate (14) with titanium (Ti) doping and low thermal expansion properties, using an ion beam sputtering method. The thickness of the reflective layer (13) was 280 nm. Next, a protective layer (12) made of ruthenium (Ru) was deposited on the reflective layer (13) to a thickness of 3.5 nm. Next, while flowing argon (Ar) and nitrogen (N2) into the chamber, sputtering of chromium (Cr) was performed to deposit a chromium nitride (CrN) film with a thickness of 14 nm as the first absorption layer (10a) on top of the protective layer (12). A compositional analysis of the first absorption layer (10a) was performed using a Rutherford Back Scattering (RBS) instrument (manufactured by Kobe Steel, Ltd., model number: HRBS500). The compositional content of chromium (Cr) with a positive hydrogen dissolution energy Es in the first absorption layer (10a) was found to be 54 at%. Subsequently, by performing binary sputtering of ruthenium (Ru) and chromium (Cr) while introducing argon (Ar), a second absorption layer (10b) of ruthenium (Ru) and chromium (Cr) alloy film with a thickness of 45 nm was deposited on the first absorption layer (10a). Next, a conductive film (15) made of chromium nitride (CrN) was deposited to a thickness of 100 nm on the side of the substrate (14) where the reflective film (13) was not formed, and a reflective photomask blank (100) was fabricated. Similar to the compositional analysis of the first absorption layer (10a), the compositional analysis of the second absorption layer (10b) was performed using a Rutherford backscattering (RBS) instrument. The total content of metallic elements (ruthenium (Ru) and chromium (Cr)) with positive hydrogen dissolution heat Es in the second absorption layer (10b) was found to be 100 at%.

[0068] <Fabrication of reflective photomasks> Next, the method for fabricating a reflective photomask will be explained using Figures 5 and 7 to 9. As shown in Figure 7, a positive-type chemically amplified resist (product name: XFP-355: manufactured by Fujifilm Electronic Materials Corporation) was applied by spin coating to the exposed surface of the second absorption layer (10b) of the reflective photomask blank prepared above to a thickness of 100 nm, and baked at 110°C for 10 minutes to form a resist film (16) (Figure 7). Next, using known lithography techniques, a predetermined pattern was drawn on the resist film (16) using an electron beam lithography system (model number: EBM7500T, manufactured by Newflare Technology Co., Ltd.), and patterning was performed on the main pattern area by alkaline development, obtaining the resist pattern shown in Figure 8. Subsequently, the absorption layer (10) was patterned by dry etching using a fluorine-based gas and a chlorine-based gas, with the resist pattern as an etching mask. As a result, an absorption pattern layer (101) was formed in the main pattern region (20) (not shown), as shown in Figure 9. Next, after removing the resist by peeling, a light-shielding band (22) (not shown) was formed on the absorption pattern layer (101) using known lithography techniques to obtain a reflective photomask (200b) as shown in Figure 5.

[0069] <Rating> The reflective photomasks fabricated as described above were evaluated for etching properties, cleaning resistance, hydrogen radical resistance, and modification properties using the following methods. During the fabrication of the reflective photomask, the etching time for forming the absorption pattern layer (101) was 110 seconds. Furthermore, the change in reflectivity of the reflective photomask, measured using the method described below, was 0.4%. The evaluation results are shown in Table 1.

[0070] [Etching properties] The etching time was measured when forming the absorption pattern layer (101) during the fabrication of a reflective photomask, and the etchability was evaluated according to the following evaluation criteria. If the etchability evaluation is "A" or "B", it can be determined that the processability is excellent. -Evaluation Criteria- "A": The etching time was less than 120 seconds, indicating good etching performance. "B": The etching time was between 120 seconds and 240 seconds, indicating that etching was possible. "C": The etching time was 240 seconds or more, indicating that the etching process was difficult.

[0071] [Wash resistance] The reflective photomasks prepared as described above were treated with sulfuric acid hydrogen peroxide solution (SPM) at 70°C for 10 minutes, then washed with ultrapure water, treated with ammonia hydrogen peroxide solution (APM) at 25°C for 10 minutes, and then washed with ultrapure water. This washing process constituted one set, and 10 sets were treated for the reflective photomasks (200b) prepared as described above. The reflectance of reflective photomasks before and after cleaning was measured using a reflectometer, and the change in reflectance was determined. The cleaning resistance of the reflectance changes was evaluated according to the following evaluation criteria. If the wash resistance rating is "A" or "B", it can be determined that the material has excellent wash resistance. -Evaluation Criteria- "A": The change in reflectance before and after cleaning, as measured by a reflectometer, was less than 0.8%, indicating good cleaning resistance. "B": The change in reflectivity was between 0.8% and 1.6%, indicating practically acceptable cleaning resistance. "C": The change in reflectivity was 1.6% or more, which was an unacceptable level for practical use.

[0072] [Hydrogen radical resistance] The reflective photomask (200b) prepared as described above was treated by flowing 50 sccm of hydrogen gas through it using a 2.45 GHz microwave plasma device. After 4 hours of treatment, the appearance of the reflective photomask was visually observed, and its hydrogen radical resistance was evaluated based on the following evaluation criteria. If the hydrogen radical resistance rating is "A", it can be determined that the product has excellent hydrogen radical resistance. -Evaluation Criteria- "A": No change was observed in the appearance of the reflective photomask. "B": Delamination of the film was observed between the absorption layer (10) and the protective layer (12).

[0073] [Correction workability] Using an electron beam correction machine (MeRiT: manufactured by Carl Zeiss), the etching rate of the absorption layer (10) was calculated by etching the absorption layer (10) at three different processing times. Similarly, the etching rate of the protective layer (12) was calculated by etching the protective layer (12) at three different processing times. The etching rate of the absorption layer (10), based on the etching rate of the protective layer (12), was used as the selection ratio, and the processability for correction was evaluated based on the following evaluation criteria. A larger selection ratio indicates a greater difference in etching rates between the protective layer and the absorption layer, and a greater tolerance for the settings during correction (i.e., a better correction margin). If the evaluation of the processability for correction is "A" or "B", it can be said that correction is possible because the damage to the protective layer has been suppressed. -Evaluation Criteria- "A": The selection ratio was 2 or higher, and the correction margin was good. "B": The selection ratio was between 1 and 2, and it was correctable. "C": The selection ratio was less than 1, so it could not be corrected.

[0074] (Example 2) A reflective photomask blank (100) and a reflective photomask (200b) were prepared in the same manner as in Example 1, except that a first absorption layer (10a) was deposited on a protective layer (12) by binary sputtering of molybdenum (Mo) and tantalum (Ta) while introducing argon (Ar) to form an alloy film with a thickness of 20 nm, and a second absorption layer (10b) was deposited on the first absorption layer (10a) by binary sputtering of platinum (Pt) and tantalum (Ta) while introducing argon (Ar) to form an alloy film with a thickness of 40 nm. At this time, when the content of metal elements having a positive hydrogen dissolution energy Es was measured using the same measurement method as in Example 1, the content of metal elements having a positive hydrogen dissolution energy Es in the first absorption layer (10a) was 50 at%, and the content of metal elements having a positive hydrogen dissolution energy Es in the second absorption layer (10b) was 40 at%. The etching time for forming the absorption pattern layer (101) during photomask fabrication was 105 seconds. Etching properties, cleaning resistance, hydrogen radical resistance, and modification properties were evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0075] (Example 3) A reflective photomask blank (100) and a reflective photomask (200b) were prepared in the same manner as in Example 1, except that a first absorption layer (10a) was deposited on a protective layer (12) by performing binary sputtering of tungsten (W) and tantalum (Ta) while introducing argon (Ar) to achieve a thickness of 40 nm for the alloy film, and a second absorption layer (10b) was deposited on the first absorption layer (10a) by performing binary sputtering of iridium (Ir) and tantalum (Ta) while introducing argon (Ar) to achieve a thickness of 22 nm for the alloy film. At this time, when the content of metal elements having a positive hydrogen dissolution energy Es was measured in the same manner as in Example 1, the content of metal elements having a positive hydrogen dissolution energy Es in the first absorption layer (10a) was 40 at%, and the content of metal elements having a positive hydrogen dissolution energy Es in the second absorption layer (10b) was 50 at%. The etching time for forming the absorption pattern layer (101) during photomask fabrication was 115 seconds. Furthermore, the obtained reflective photomasks were evaluated for etching processability, cleaning resistance, hydrogen radical resistance, and modification processability in the same manner as in Example 1. The results are shown in Table 1.

[0076] (Example 4) A reflective photomask blank (100) and a reflective photomask (200b) were prepared in the same manner as in Example 1, except that a first absorption layer (10a) was deposited on a protective layer (12) by binary sputtering of aluminum (Al) and tantalum (Ta) while introducing argon (Ar) to achieve a thickness of 30 nm for the alloy film, and a second absorption layer (10b) was deposited on the first absorption layer (10a) by binary sputtering of platinum (Pt) and tantalum (Ta) while introducing argon (Ar) to achieve a thickness of 30 nm for the alloy film. When the content of metal elements with a positive hydrogen dissolution energy Es was measured using the same method as in Example 1, the content of metal elements with a positive hydrogen dissolution energy Es in the first absorption layer (10a) was 40 at%, and the content of metal elements with a positive hydrogen dissolution energy Es in the second absorption layer (10b) was also 40 at%. Furthermore, the obtained reflective photomask (200b) was evaluated for etching processability, cleaning resistance, hydrogen radical resistance, and modification processability in the same manner as in Example 1. The results are shown in Table 1. The etching time for forming the absorption pattern layer (101) during photomask fabrication was 140 seconds.

[0077] (Example 5) A reflective photomask blank (100) and a reflective photomask (200b) were obtained in the same manner as in Example 1, except that a first absorption layer (10a) was formed on a protective layer (12) by binary sputtering of platinum (Pt) and tantalum (Ta) while introducing argon (Ar) to form an alloy film with a thickness of 22 nm, and a second absorption layer (10b) was formed on the first absorption layer (10a) by sputtering chromium (Cr) while flowing argon (Ar) and nitrogen (N2) to form a second absorption layer (10b) of chromium nitride (CrN) with a thickness of 35 nm. At this time, when the content of metal elements having a positive hydrogen dissolution energy Es was measured using the same measurement method as in Example 1, the content of metal elements having a positive hydrogen dissolution energy Es in the first absorption layer (10a) was 40 at%, and the content of metal elements having a positive hydrogen dissolution energy Es in the second absorption layer (10b) was 54 at%. The etching time for forming the absorption pattern layer (101) during photomask fabrication was 95 seconds. Etching properties, cleaning resistance, hydrogen radical resistance, and modification properties were evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0078] (Example 6) A reflective photomask blank (100) and a reflective photomask (200b) were obtained in the same manner as in Example 1, except that a first absorption layer (10a) was deposited on a protective layer (12) by binary sputtering of ruthenium (Ru) and chromium (Cr) while introducing argon (Ar) to achieve an alloy film thickness of 15 nm, and a second absorption layer (10b) was deposited on the first absorption layer (10a) by binary sputtering of molybdenum (Mo) and tantalum (Ta) to achieve an alloy film thickness of 40 nm. At this time, the content of metal elements with a positive hydrogen dissolution energy Es was measured in the same manner as in Example 1, and the content of metal elements with a positive hydrogen dissolution energy Es in the first absorption layer (10a) was 100 at%, and the content of metal elements with a positive hydrogen dissolution energy Es in the second absorption layer (10b) was 40 at%. The etching time for forming the absorption pattern layer (101) during photomask fabrication was 90 seconds. The obtained reflective photomask (200b) was evaluated for etching processability, cleaning resistance, hydrogen radical resistance, and modification processability in the same manner as in Example 1. The results are shown in Table 1.

[0079] (Example 7) A reflective photomask blank (100) and a reflective photomask (200b) were obtained in the same manner as in Example 1, except that a first absorption layer (10a) was deposited on a protective layer (12) by binary sputtering of iridium (Ir) and tantalum (Ta) while introducing argon (Ar) to achieve a thickness of 20 nm for the alloy film, and a second absorption layer (10b) was deposited on the first absorption layer (10a) by binary sputtering of tungsten (W) and tantalum (Ta) while introducing argon (Ar) to achieve a thickness of 35 nm for the alloy film. At this time, when the content of metal elements with a positive hydrogen dissolution energy Es was measured using the same measurement method as in Example 1, the content of metal elements with a positive hydrogen dissolution energy Es in the first absorption layer (10a) was 50 at%, and the content of metal elements with a positive hydrogen dissolution energy Es in the second absorption layer (10b) was 40 at%. The etching time for forming the absorption pattern layer (101) during photomask fabrication was 85 seconds. The obtained reflective photomask (200b) was evaluated for etching processability, cleaning resistance, hydrogen radical resistance, and modification processability in the same manner as in Example 1. The results are shown in Table 1.

[0080] (Example 8) A reflective photomask blank (100) and a reflective photomask (200b) were obtained in the same manner as in Example 1, except that a first absorption layer (10a) was formed on a protective layer (12) by binary sputtering of molybdenum (Mo) and tantalum (Ta) while introducing argon (Ar) to form an alloy film with a thickness of 20 nm, and a second absorption layer (10b) was formed on the first absorption layer (10a) by binary sputtering of chromium (Cr) and tantalum (Ta) while introducing argon (Ar) to form an alloy film with a thickness of 40 nm. At this time, the content of metal elements with a positive hydrogen dissolution energy Es was measured using the same measurement method as in Example 1, and the content of metal elements with a positive hydrogen dissolution energy Es in the first absorption layer (10a) was 50 at%, and the content of metal elements with a positive hydrogen dissolution energy Es in the second absorption layer (10b) was 40 at%. The etching time for forming the absorption pattern layer (101) during photomask fabrication was 85 seconds. The obtained reflective photomask (200b) was evaluated for etching processability, cleaning resistance, hydrogen radical resistance, and modification processability in the same manner as in Example 1. The results are shown in Table 1.

[0081] (Example 9) A reflective photomask blank (100) and a reflective photomask (200b) were obtained in the same manner as in Example 1, except that a first absorption layer (10a) was deposited on a protective layer (12) by binary sputtering of iridium (Ir) and tantalum (Ta) while introducing argon (Ar) to achieve an alloy film thickness of 20 nm, and a second absorption layer (10b) was deposited on the first absorption layer (10a) by binary sputtering of platinum (Pt) and tantalum (Ta) to achieve an alloy film thickness of 40 nm. At this time, the content of metal elements with a positive hydrogen dissolution energy Es was measured in the same manner as in Example 1, and the content of metal elements with a positive hydrogen dissolution energy Es in the first absorption layer (10a) was 50 at%, and the content of metal elements with a positive hydrogen dissolution energy Es in the second absorption layer (10b) was 40 at%. The etching time for forming the absorption pattern layer (101) during photomask fabrication was 180 seconds. The obtained reflective photomask (200b) was evaluated for etching processability, cleaning resistance, hydrogen radical resistance, and modification processability in the same manner as in Example 1. The results are shown in Table 1.

[0082] (Example 10) A reflective photomask blank (100) and a reflective photomask (200b) were obtained in the same manner as in Example 1, except that a first absorption layer (10a) was deposited on a protective layer (12) by binary sputtering of ruthenium (Ru) and molybdenum (Mo) while introducing argon (Ar) to achieve an alloy film thickness of 20 nm, and a second absorption layer (10b) was deposited on the first absorption layer (10a) by binary sputtering of rhodium (Rh) and tantalum (Ta) to achieve an alloy film thickness of 40 nm. At this time, the content of metal elements with positive hydrogen dissolution energy Es was measured in the same manner as in Example 1, and the content of metal elements with positive hydrogen dissolution energy Es in the first absorption layer (10a) was 100 at%, and the content of metal elements with positive hydrogen dissolution energy Es in the second absorption layer (10b) was 40 at%. The etching time for forming the absorption pattern layer (101) during photomask fabrication was 190 seconds. The obtained reflective photomask (200b) was evaluated for etching processability, cleaning resistance, hydrogen radical resistance, and modification processability in the same manner as in Example 1. The results are shown in Table 1.

[0083] (Example 11) <Fabrication of reflective photomask blank (100b)> As shown in Figure 2, a reflective layer (13) was formed by stacking 40 layers of silicon (Si) and molybdenum (Mo) in pairs on a synthetic quartz substrate (14) with titanium (Ti) doping and low thermal expansion properties, using ion beam sputtering deposition. The thickness of the reflective layer (13) was 280 nm. Next, a protective layer (12) made of ruthenium (Ru) was deposited on the reflective layer (13) to a thickness of 3.5 nm. Next, by introducing argon (Ar) into the chamber and performing binary sputtering of iridium (Ir) and tungsten (W), an absorption layer (10) was deposited on the alloy film to a thickness of 60 nm. A compositional analysis of the absorption layer (10) using a Rutherford backscattering (RBS) instrument (manufactured by Kobe Steel, Ltd., model number: HRBS500) revealed that the content of metal elements with positive hydrogen dissolution energy Es was 100 at%. Next, a conductive film (15) made of chromium nitride (CrN) was deposited to a thickness of 100 nm on the side of the substrate (14) where the reflective layer (13) was not formed, and a reflective photomask blank (100b) was fabricated.

[0084] <Fabrication of reflective photomasks> A reflective photomask (200a) as shown in Figure 4 was obtained using known lithography techniques in the same manner as in Example 1, except that a reflective photomask blank (100b) was used. The etching time for forming the absorption pattern layer (101) during photomask fabrication was 90 seconds. Etching properties, cleaning resistance, hydrogen radical resistance, and modification properties were evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0085] (Example 12) A reflective photomask blank (100b) and a reflective photomask (200a) were obtained in the same manner as in Example 11, except that an absorption layer (10) was formed on a protective layer (12) by binary sputtering of ruthenium (Ru) and chromium (Cr) while introducing argon (Ar) so that the thickness of the alloy film was 50 nm. At this time, the content of metal elements with a positive hydrogen dissolution energy Es was measured in the same manner as in Example 1, and the content of metal elements with a positive hydrogen dissolution energy Es in the absorption layer (10) was found to be 100 at%. The etching time for forming the absorption pattern layer (101) during photomask fabrication was 80 seconds. Furthermore, the obtained reflective photomasks were evaluated for etching processability, cleaning resistance, hydrogen radical resistance, and modification processability in the same manner as in Example 1. The results are shown in Table 1.

[0086] (Example 13) A reflective photomask blank (100b) and a reflective photomask (200a) were obtained in the same manner as in Example 11, except that an absorption layer (10) was formed on a protective layer (12) by binary sputtering of platinum (Pt) and molybdenum (Mo) while introducing argon (Ar) so that the thickness of the alloy film was 55 nm. At this time, the content of metal elements with a positive hydrogen dissolution energy Es was measured in the same manner as in Example 1, and the content of metal elements with a positive hydrogen dissolution energy Es in the absorption layer (10) was found to be 100 at%. The etching time for forming the absorption pattern layer (101) during photomask fabrication was 85 seconds. Furthermore, etching properties, cleaning resistance, hydrogen radical resistance, and modification properties were evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0087] (Example 14) A reflective photomask blank (100b) and a reflective photomask (200a) were obtained in the same manner as in Example 11, except that an absorption layer (10) was formed on a protective layer (12) by performing binary sputtering of molybdenum (Mo) and tantalum (Ta) while introducing argon (Ar) so that the thickness of the alloy film was 60 nm. At this time, the content of metal elements with a positive hydrogen dissolution energy Es was measured in the same manner as in Example 1, and the content of metal elements with a positive hydrogen dissolution energy Es in the absorption layer (10) was found to be 50 at%. The etching time for forming the absorption pattern layer (101) during photomask fabrication was 80 seconds. Furthermore, the obtained reflective photomasks were evaluated for etching processability, cleaning resistance, hydrogen radical resistance, and modification processability in the same manner as in Example 1. The results are shown in Table 1.

[0088] (Example 15) A reflective photomask blank (100b) and a reflective photomask (200a) were obtained in the same manner as in Example 11, except that an absorption layer (10) was formed on a protective layer (12) by performing binary sputtering of ruthenium (Ru) and tantalum (Ta) while introducing argon (Ar) so that the thickness of the alloy film was 60 nm. At this time, the content of metal elements with a positive hydrogen dissolution energy Es was measured in the same manner as in Example 1, and the content of metal elements with a positive hydrogen dissolution energy Es in the absorption layer (10) was found to be 40 at%. The etching time for forming the absorption pattern layer (101) during photomask fabrication was 130 seconds. Furthermore, the obtained reflective photomasks were evaluated for etching processability, cleaning resistance, hydrogen radical resistance, and modification processability in the same manner as in Example 1. The results are shown in Table 1.

[0089] (Example 16) A reflective photomask blank (100b) and a reflective photomask (200a) were obtained in the same manner as in Example 11, except that an absorption layer (10) was formed on a protective layer (12) by performing binary sputtering of aluminum (Al) and tantalum (Ta) while introducing argon (Ar) so that the thickness of the alloy film was 58 nm. At this time, the content of metal elements with a positive hydrogen dissolution energy Es was measured in the same manner as in Example 1, and the content of metal elements with a positive hydrogen dissolution energy Es in the absorption layer (10) was found to be 40 at%. The etching time for forming the absorption pattern layer (101) during photomask fabrication was 140 seconds. Furthermore, the obtained reflective photomasks were evaluated for etching processability, cleaning resistance, hydrogen radical resistance, and modification processability in the same manner as in Example 1. The results are shown in Table 1.

[0090] (Example 17) A reflective photomask blank (100b) and a reflective photomask (200a) were obtained in the same manner as in Example 11, except that an absorption layer (10) was formed on a protective layer (12) by binary sputtering of platinum (Pt) and ruthenium (Ru) while introducing argon (Ar) so that the thickness of the alloy film was 60 nm. At this time, the content of metal elements with a positive hydrogen dissolution energy Es was measured in the same manner as in Example 1, and the content of metal elements with a positive hydrogen dissolution energy Es in the absorption layer (10) was found to be 100 at%. The etching time for forming the absorption pattern layer (101) during photomask fabrication was 130 seconds. Furthermore, the obtained reflective photomasks were evaluated for etching processability, cleaning resistance, hydrogen radical resistance, and modification processability in the same manner as in Example 1. The results are shown in Table 1.

[0091] (Example 18) A reflective photomask blank (100b) and a reflective photomask (200a) were obtained in the same manner as in Example 11, except that an absorption layer (10) was formed on a protective layer (12) by performing binary sputtering of molybdenum (Mo) and chromium (Cr) while introducing argon (Ar) so that the thickness of the alloy film was 60 nm. At this time, the content of metal elements with a positive hydrogen dissolution energy Es was measured in the same manner as in Example 1, and the content of metal elements with a positive hydrogen dissolution energy Es in the absorption layer (10) was found to be 100 at%. The etching time for forming the absorption pattern layer (101) during photomask fabrication was 80 seconds. Furthermore, the obtained reflective photomasks were evaluated for etching processability, cleaning resistance, hydrogen radical resistance, and modification processability in the same manner as in Example 1. The results are shown in Table 1.

[0092] (Example 19) <Fabrication of reflective photomask blank (100c)> As shown in Figure 3, a reflective layer (13) was formed by stacking 40 layers of silicon (Si) and molybdenum (Mo) in pairs on a synthetic quartz substrate (14) with titanium (Ti) doping and low thermal expansion properties, using ion beam sputtering deposition. The thickness of the reflective layer (13) was 280 nm. Next, a protective layer (12) made of ruthenium (Ru) was deposited on the reflective layer (13) to a thickness of 3.5 nm. Next, a TaON buffer layer (11) was formed on the protective layer (12) by sputtering tantalum (Ta) while flowing argon (Ar), oxygen (O2), and nitrogen (N2) over it, so that the film thickness was 10 nm. Next, an absorption layer (10) was deposited on the buffer layer (11) by performing binary sputtering of platinum (Pt) and molybdenum (Mo) while introducing argon (Ar) into the chamber, so that the alloy film thickness was 60 nm. A compositional analysis of the absorption layer (10) was performed using a Rutherford backscattering (RBS) instrument (manufactured by Kobe Steel, Ltd., model number: HRBS500). The compositional content of metal elements with positive hydrogen dissolution energy Es in the absorption layer (10) was found to be 100 at%. Next, a conductive film (15) made of chromium nitride (CrN) was deposited to a thickness of 100 nm on the side of the substrate (14) where the reflective layer (13) was not formed, and a reflective photomask blank (100b) was fabricated.

[0093] <Fabrication of reflective photomasks> A reflective photomask (200c) as shown in Figure 6 was obtained using known lithography techniques in the same manner as in Example 1, except that a reflective photomask blank (100b) was used. The etching time for forming the absorption pattern layer (101) during photomask fabrication was 95 seconds. Etching properties, cleaning resistance, hydrogen radical resistance, and modification properties were evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0094] (Example 20) A reflective photomask blank (100b) and a reflective photomask (200c) were obtained in the same manner as in Example 19, except that an absorption layer (10) was formed on a buffer layer (11) by performing binary sputtering of molybdenum (Mo) and tantalum (Ta) while introducing argon (Ar) so that the thickness of the alloy film was 60 nm. At this time, the content of metal elements with a positive hydrogen dissolution energy Es was measured in the same manner as in Example 1, and the content of metal elements with a positive hydrogen dissolution energy Es in the absorption layer (10) was found to be 50 at%. The etching time for forming the absorption pattern layer (101) during photomask fabrication was 95 seconds. Furthermore, etching properties, cleaning resistance, hydrogen radical resistance, and modification properties were evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0095] (Example 21) A reflective photomask blank (100b) and a reflective photomask (200c) were obtained in the same manner as in Example 19, except that an absorption layer (10) was formed on a buffer layer (11) by performing binary sputtering of ruthenium (Ru) and tantalum (Ta) while introducing argon (Ar) so that the thickness of the alloy film was 60 nm. At this time, the content of metal elements with a positive hydrogen dissolution energy Es was measured in the same manner as in Example 1, and the content of metal elements with a positive hydrogen dissolution energy Es in the absorption layer (10) was found to be 40 at%. The etching time for forming the absorption pattern layer (101) during photomask fabrication was 125 seconds. Furthermore, etching properties, cleaning resistance, hydrogen radical resistance, and modification properties were evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0096] (Example 22) A reflective photomask blank (100b) and a reflective photomask (200c) were obtained in the same manner as in Example 19, except that an absorption layer (10) was formed on a buffer layer (11) by performing binary sputtering of ruthenium (Ru) and iridium (Ir) while introducing argon (Ar) so that the thickness of the alloy film was 60 nm. At this time, the content of metal elements with a positive hydrogen dissolution energy Es was measured in the same manner as in Example 1, and the content of metal elements with a positive hydrogen dissolution energy Es in the absorption layer (10) was found to be 100 at%. The etching time for forming the absorption pattern layer (101) during photomask fabrication was 140 seconds. Furthermore, etching properties, cleaning resistance, hydrogen radical resistance, and modification properties were evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0097] (Comparative Example 1) A reflective photomask blank (100b) and a reflective photomask (200b) were obtained in the same manner as in Example 1, except that a first absorption layer (10a) was formed on a protective layer (12) by sputtering tantalum (Ta) while introducing argon (Ar) and nitrogen (N2) to form a nitride film (TaN) with a thickness of 50 nm, and a second absorption layer (10b) was formed on the first absorption layer (10a) by sputtering tantalum (Ta) while introducing argon (Ar) and oxygen (O2) to form an oxide film (TaO) with a thickness of 10 nm. At this time, the content of metal elements with a positive hydrogen dissolution energy Es was measured in the same manner as in Example 1, and the content of metal elements with a positive hydrogen dissolution energy Es in the first absorption layer (10a) and the second absorption layer (10b) was 0 at%. The etching time for forming the absorption pattern layer (101) during photomask fabrication was 80 seconds. Furthermore, etching properties, cleaning resistance, hydrogen radical resistance, and modification properties were evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0098] (Comparative Example 2) A reflective photomask blank (100b) and a reflective photomask (200b) were obtained in the same manner as in Example 1, except that a first absorption layer (10a) was formed on a protective layer (12) by sputtering tantalum (Ta) while introducing argon (Ar) and nitrogen (N2) to form a nitride film (TaN) with a thickness of 30 nm, and a second absorption layer (10b) was formed on the first absorption layer (10a) by binary sputtering of ruthenium (Ru) and tantalum (Ta) while introducing argon (Ar) to form an alloy film with a thickness of 30 nm. At this time, the content of metal elements with a positive hydrogen dissolution energy Es was measured in the same manner as in Example 1, and the content of metal elements with a positive hydrogen dissolution energy Es in the first absorption layer (10a) was 0 at%, and the content of metal elements with a positive hydrogen dissolution energy Es in the second absorption layer (10b) was 30 at%. The etching time for forming the absorption pattern layer (101) during photomask fabrication was 90 seconds. Furthermore, etching properties, cleaning resistance, hydrogen radical resistance, and modification properties were evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0099] (Comparative Example 3) A reflective photomask blank (100b) and a reflective photomask (200b) were obtained in the same manner as in Example 1, except that a first absorption layer (10a) was formed on a protective layer (12) by binary sputtering of ruthenium (Ru) and tantalum (Ta) while introducing argon (Ar) to form an oxide film (TaO) with a thickness of 25 nm, and a second absorption layer (10b) was formed on the first absorption layer (10a) by sputtering of tantalum (Ta) while introducing argon (Ar) and nitrogen (N2) to form a nitride film (TaN) with a thickness of 35 nm. At this time, the content of metal elements with a positive hydrogen dissolution energy Es was measured in the same manner as in Example 1, and the content of metal elements with a positive hydrogen dissolution energy Es in the first absorption layer (10a) was 30 at%, and the content of metal elements with a positive hydrogen dissolution energy Es in the second absorption layer (10b) was 0 at%. The etching time for forming the absorption pattern layer (101) during photomask fabrication was 85 seconds. Furthermore, etching properties, cleaning resistance, hydrogen radical resistance, and modification properties were evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0100] (Comparative Example 4) A reflective photomask blank (100b) and a reflective photomask (200b) were obtained in the same manner as in Example 1, except that a first absorption layer (10a) was deposited on a protective layer (12) by binary sputtering of ruthenium (Ru) and tantalum (Ta) while introducing argon (Ar) to form an alloy film with a thickness of 20 nm, and a second absorption layer (10b) was deposited on the first absorption layer (10a) by binary sputtering of platinum (Pt) and tantalum (Ta) while introducing argon (Ar) to form an alloy film with a thickness of 30 nm. At this time, when the content of metal elements with a positive hydrogen dissolution energy Es was measured in the same manner as in Example 1, the content of metal elements with a positive hydrogen dissolution energy Es in the first absorption layer (10a) was 30 at%, and the content of metal elements with a positive hydrogen dissolution energy Es in the second absorption layer (10b) was also 30 at%. The etching time for forming the absorption pattern layer (101) during photomask fabrication was 130 seconds. Furthermore, etching properties, cleaning resistance, hydrogen radical resistance, and modification properties were evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0101] (Comparative Example 5) A reflective photomask blank (100b) and a reflective photomask (200a) were obtained in the same manner as in Example 11, except that an absorption layer (10) was formed on a protective layer (12) by sputtering tantalum (Ta) while introducing argon (Ar) and oxygen (O2) to form an oxide film (TaO) with a thickness of 50 nm. At this time, the content of metal elements with a positive hydrogen dissolution energy Es was measured in the same manner as in Example 1, and the content of metal elements with a positive hydrogen dissolution energy Es in the absorption layer (10) was found to be 0 at%. The etching time for forming the absorption pattern layer (101) during photomask fabrication was 85 seconds. Furthermore, etching properties, cleaning resistance, hydrogen radical resistance, and modification properties were evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0102] (Comparative Example 6) A reflective photomask blank (100b) and a reflective photomask (200a) were obtained in the same manner as in Example 11, except that an absorption layer (10) was formed on a protective layer (12) by performing binary sputtering of ruthenium (Ru) and tantalum (Ta) while introducing argon (Ar) to achieve an alloy film thickness of 46 nm. At this time, the content of metal elements with a positive hydrogen dissolution energy Es was measured in the same manner as in Example 1, and the content of metal elements with a positive hydrogen dissolution energy Es in the absorption layer (10) was found to be 30 at%. The etching time for forming the absorption pattern layer (101) during photomask fabrication was 140 seconds. Furthermore, etching properties, cleaning resistance, hydrogen radical resistance, and modification properties were evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0103] (Comparative Example 7) A reflective photomask blank (100b) and a reflective photomask (200c) were obtained in the same manner as in Example 19, except that an absorption layer (10) was formed on a buffer layer (11) by performing binary sputtering of ruthenium (Ru) and tantalum (Ta) while introducing argon (Ar) so that the thickness of the alloy film was 55 nm. At this time, the content of metal elements with a positive hydrogen dissolution energy Es was measured in the same manner as in Example 1, and the content of metal elements with a positive hydrogen dissolution energy Es in the absorption layer (10) was found to be 30 at%. The etching time for forming the absorption pattern layer (101) during photomask fabrication was 95 seconds. Furthermore, etching properties, cleaning resistance, hydrogen radical resistance, and modification properties were evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0104] [Table 1]

[0105] In the first embodiment, the reflective photomask blanks of Examples 1 to 10 have an absorption layer (10) which is formed by laminating at least one pair of absorption layers (10a) and a second absorption layer (10b). Since each of the first absorption layer (10a) and the second absorption layer (10b) contains at least 40 at% of one or more metal elements having a positive hydrogen dissolution energy Es, it can be seen that the hydrogen radical resistance of the resulting reflective photomask is improved compared to the reflective photomask blanks of Comparative Examples 1 to 4. In the first absorption layer (10a) and the second absorption layer (10b), it is preferable to include 40 at% or more of any of the following metal elements having a positive hydrogen dissolution energy Es: molybdenum (Mo), tungsten (W), and chromium (Cr) from the first material group, or platinum (Pt), ruthenium (Ru), and iridium (Ir) from the second material group. This is preferable from the viewpoint of widening the process margin in photomask manufacturing, such as etching processability and cleaning resistance. More preferably, the process margin in photomask manufacturing can be widened by having the first absorption layer (10a) contain either the first or second material group, and the second absorption layer (10b) contain 40 at% or more of the other material group.

[0106] The reflective photomask blanks of Examples 11 to 18 according to the second embodiment show improved hydrogen radical resistance of the resulting reflective photomasks compared to the reflective photomask blanks of Comparative Examples 5 and 6, due to the absorption layer (10) containing 40 at% or more of a metal element having a positive hydrogen dissolution energy Es. It is preferable that the absorption layer (10) contains 40 at% or more of any of the first material group consisting of molybdenum (Mo), tungsten (W), and chromium (Cr) or the second material group consisting of platinum (Pt), ruthenium (Ru), and iridium (Ir) as metal elements having a positive hydrogen dissolution energy Es, from the viewpoint of widening the process margin in photomask manufacturing, such as etching processability and cleaning resistance. It is even more preferable that the absorption layer (10) contains at least one metal element from each of the first and second material groups as metal elements having a positive hydrogen dissolution energy Es, from the viewpoint of widening the margin in the photomask manufacturing process.

[0107] The reflective photomask blanks of Examples 19 to 22 according to the third embodiment show that the resulting reflective photomasks have superior hydrogen radical resistance compared to the reflective photomask blank of Comparative Example 7, because the absorption layer (10) placed on the buffer layer (11) contains 40 at% or more of a metal element having a positive hydrogen dissolution energy Es. It is preferable that the absorption layer (10) contains 40 at% or more of any of the first material group molybdenum (Mo), tungsten (W), and chromium (Cr) or the second material group platinum (Pt), ruthenium (Ru), and iridium (Ir) as metal elements having a positive hydrogen dissolution energy Es, from the viewpoint of widening the process margin in photomask manufacturing, such as etching processability and cleaning resistance. It is even more preferable that the absorption layer (10) contains at least one metal element from each of the first and second material groups as a metal element having a positive hydrogen dissolution energy Es, from the viewpoint of widening the process margin in photomask manufacturing. Furthermore, in the reflective photomask blank according to the third embodiment, it is preferable that the buffer layer contains tantalum (Ta) or chromium (Cr) from the viewpoint of widening the process margin. In the reflective photomask blanks of Comparative Examples 1 to 7, the content of metal elements with positive hydrogen dissolution energy Es in the absorption layer (10) is less than 40 at%, so it is thought that hydrogen radicals generated by the microwave plasma device penetrate and accumulate inside the absorption layer, causing film delamination around the protective layer. [Industrial applicability]

[0108] The reflective photomask blanks and reflective photomasks fabricated using the reflective photomask blanks described herein can be suitably used for pattern formation by EUV exposure in the manufacturing process of semiconductor integrated circuits and the like. [Explanation of Symbols]

[0109] 10. Absorption layer 10a...First absorption layer 10b...Second absorption layer 11. Buffer layer 12...protective layer 13...Reflection layer 14... Circuit board 15. Conductive film 16. Resist film 100, 100a, 100b, 100c... Reflective photomask blanks 101, 101a, 101b... Absorption pattern layer 102...Buffer layer 20...Main pattern area 21... Peripheral area 22. Shading band 23...outer area 200a, 200b, 200c... Reflective photomasks

Claims

1. circuit board and A reflective layer that reflects EUV light is disposed on the substrate, A protective layer disposed on the reflective layer to protect the reflective layer, The protective layer comprises an absorbing layer that absorbs EUV light, The absorbent layer comprises a first absorbent layer and a second absorbent layer. A reflective photomask blank in which the first absorption layer and the second absorption layer each contain 40 at% or more of a metallic element having a positive hydrogen dissolution energy Es.

2. The reflective photomask blank according to claim 1, wherein the metallic element having a positive hydrogen dissolution energy Es is at least one metallic element selected from the following first group of materials and the following second group of materials; First group of materials: molybdenum (Mo), tungsten (W), and chromium (Cr); The second group of materials: platinum (Pt), ruthenium (Ru), and iridium (Ir).

3. The reflective photomask blank according to claim 2, wherein the first absorption layer comprises at least one metallic element selected from the first group of materials, and the second absorption layer comprises at least one metallic element selected from the second group of materials.

4. The reflective photomask blank according to claim 2, wherein the first absorption layer comprises at least one metallic element selected from the second group of materials, and the second absorption layer comprises at least one metallic element selected from the first group of materials.

5. circuit board and A reflective layer that reflects EUV light is disposed on the substrate, A protective layer placed on the reflective layer to protect the reflective layer, The protective layer comprises an absorbing layer that absorbs EUV light, The absorption layer is a reflective photomask blank containing 40 at% or more of a metallic element having a positive hydrogen dissolution energy Es.

6. The reflective photomask blank according to claim 5, wherein the metallic element having a positive hydrogen dissolution energy Es is at least one metallic element selected from the following first group of materials or the following second group of materials; First group of materials: molybdenum (Mo), tungsten (W), and chromium (Cr); The second group of materials: platinum (Pt), ruthenium (Ru), and iridium (Ir).

7. The reflective photomask blank according to claim 6, wherein the metallic element having a positive hydrogen dissolution energy Es is at least one metallic element selected from the first material group and the second material group.

8. circuit board and A reflective layer that reflects EUV light is disposed on the substrate, A protective layer placed on the reflective layer to protect the reflective layer, A buffer layer disposed on the protective layer, The buffer layer comprises an absorption layer that absorbs EUV light, The absorption layer is a reflective photomask blank containing 40 at% or more of a metallic element having a positive hydrogen dissolution energy Es.

9. The reflective photomask blank according to claim 8, wherein the metallic element having a positive hydrogen dissolution energy Es is at least one metallic element selected from the following first group of materials or second group of materials; First group of materials: molybdenum (Mo), tungsten (W), and chromium (Cr); The second group of materials: platinum (Pt), ruthenium (Ru), and iridium (Ir).

10. The reflective photomask blank according to claim 9, wherein the metallic element having a positive hydrogen dissolution energy Es is at least one metallic element selected from the first material group and the second material group.

11. The reflective photomask blank according to claim 8, wherein the buffer layer comprises tantalum (Ta) or chromium (Cr).

12. A reflective photomask fabricated using a reflective photomask blank according to any one of claims 1 to 11.

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