Reflective photomask

Abstract

The objective of the present invention is to provide a reflective photomask that can have excellent hydrogen radical resistance as well as less deterioration in transferability caused by phase differences in a reflective portion, while also allowing for improved adhesion (interlayer adhesion) between a capping layer and a protective layer. A reflective mask (10) according to the present embodiment comprises a substrate (1), a multilayer reflective film (2), a capping layer (3), an absorptive portion (4), and a protective layer (5) formed on top of the capping layer (3), on top of the absorptive portion (4), and on lateral surfaces of the absorptive portion (4), wherein the absorptive portion (4) has an extinction coefficient k of 0.04 or greater with respect to EUV light, the capping layer (3) and the protective layer (5) are formed using the same material, a reflective portion, which is the region on top of the capping layer (3) where the absorptive portion (4) is not formed, has a reflectance of 50% or greater with respect to EUV light, the combined thickness of the capping layer (3) and the protective layer (5) is 3 nm or greater, and the capping layer (3) and the protective layer (5) are resistant to hydrogen radicals.

Description

Reflective Photomask

[0001] The present invention relates to a reflective photomask used in the manufacture of semiconductor devices and the like.

[0002] In the manufacturing process of semiconductor devices, the miniaturization of semiconductor devices has led to an increasing demand for miniaturization of photolithography technology. The minimum resolution dimension of a transfer pattern in photolithography is highly dependent on the wavelength of the exposure light source, and the shorter the wavelength, the smaller the minimum resolution dimension. For this reason, the exposure light source has been replaced from the conventional 193 nm wavelength ArF excimer laser light to light in the EUV (Extreme Ultra Violet) region with a wavelength of 13.5 nm.

[0003] Since light in the EUV region is absorbed at a high rate by most materials, a reflective photomask is used as a photomask for EUV exposure (EUV mask) (see, for example, Patent Document 1). Patent Document 1 discloses an EUV photomask obtained by forming a reflective layer made of a multilayer film in which molybdenum (Mo) layers and silicon (Si) layers are alternately stacked on a glass substrate, forming a light absorbing layer mainly composed of tantalum (Ta) thereon, and forming a pattern on this light absorbing layer.

[0004] Furthermore, as mentioned above, EUV lithography cannot use refractive optical systems that utilize the transmission of light, and therefore the optical components of the exposure machine are reflective (mirrors) rather than lenses. This poses the problem that the light incident on the reflective photomask (EUV mask) and the light reflected from the EUV mask cannot be designed to be coaxial. Normally, 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 reflected at an angle of minus 6 degrees is guided onto the semiconductor substrate.

[0005] As described above, in EUV lithography, the optical axis is tilted via a mirror, which can cause a problem known as the "shadow effect," in which the EUV light incident on the EUV mask casts a shadow on the mask pattern (patterned light-absorbing layer) of the EUV mask. Current EUV mask blanks use a tantalum (Ta)-based film with a thickness of 60 to 90 nm as the light-absorbing layer. When pattern transfer exposure is performed using an EUV mask fabricated using this mask blank, depending on the relationship between the incident direction of the EUV light and the orientation of the mask pattern, a decrease in contrast may occur at the edge portions of the mask pattern that are shadowed. This can lead to problems such as increased line edge roughness of the transferred pattern on the semiconductor substrate and an inability to form the desired line width, resulting in a deterioration in transfer performance.

[0006] Therefore, studies have been conducted on a reflective photomask blank in which the light absorption layer is changed from tantalum (Ta) to a material having a high absorbency (extinction coefficient) for EUV light, or a material with high absorbency is added to tantalum (Ta). For example, Patent Document 1 describes a reflective photomask blank in which the light absorption layer is made of a material containing 50 atomic % (at %) or more of Ta as a main component and further containing at least one element selected from Te, Sb, Pt, I, Bi, Ir, Os, W, Re, Sn, In, Po, Fe, Au, Hg, Ga, and Al.

[0007] Furthermore, a capping film is provided on the reflective layer, which is made of a multilayer film, to protect the multilayer film. As described in Patent Document 2, a film that is nearly transparent to EUV light, such as Ru, is typically used for the capping film so as not to reduce the EUV reflectivity. With this configuration, the reflective layer is protected during pattern formation, but the Ru capping layer itself is damaged, and because it is formed as a thin film, often only a film of 1 to 2 nm remains. If a photomask is used in this state, peeling of the capping film may lead to contamination of the device or exposure of the reflective layer, which may damage the reflective layer.

[0008] Furthermore, it is known that mirrors are contaminated by by-products (e.g., Sn) and carbon caused by EUV irradiation. Accumulation of contaminants on the mirror reduces the reflectivity of the mirror surface, lowering the throughput of the lithography apparatus. To address this problem, Patent Document 3 discloses a method for generating hydrogen radicals within the apparatus, causing the hydrogen radicals to react with the contaminants, and removing the contaminants from the mirror. As described above, materials used for reflective photomask blanks and reflective photomasks are required to have high resistance to hydrogen radicals.

[0009] However, some materials that are highly absorptive of EUV light have low resistance to hydrogen radicals, and there has been a problem that reflective masks made of materials with low resistance to hydrogen radicals cannot withstand long-term use. In addition, a method of covering the processed mask pattern with a coating film, as described in Patent Document 4, is considered to be effective in protecting the absorbing portion (light absorbing layer) and the capping layer.

[0010] However, in the case of covering the mask pattern with a coating film, if the capping layer and protective layer in the reflective area are made of different materials, the phase difference may adversely affect the transferability. Furthermore, the presence of an interface between the materials may cause hydrogen to accumulate at the interface, which may lead to peeling. Furthermore, forming a protective film made of a different material on a damaged film (capping layer) may cause peeling depending on the adhesion between the materials.

[0011] Japanese Patent No. 4926523 Japanese Patent No. 5803919 Japanese Patent Application Laid-Open No. 2011-530823 Japanese Patent Application Laid-Open No. 2021-071685

[0012] The present invention aims to improve resistance to hydrogen radicals by forming a protective film when manufacturing a reflective photomask, while at the same time protecting a potentially damaged capping layer. Furthermore, by forming the capping layer and the protective layer from the same material, adverse effects on transferability due to the phase difference in the reflective area are suppressed, and problems such as adhesion caused by depositing different materials are also resolved. In other words, the present invention aims to provide a reflective photomask that has excellent hydrogen radical resistance, reduces deterioration in transferability due to the phase difference in the reflective area, and can improve adhesion (interlayer adhesion) between the capping layer and the protective layer.

[0013] a capping layer formed on the reflective layer; an absorbing portion formed on a portion of the capping layer and absorbing EUV light; and a protective layer formed on the capping layer, on the absorbing portion, and on side surfaces of the absorbing portion, wherein the absorbing portion has an extinction coefficient k of 0.04 or more for EUV light, the capping layer and the protective layer are formed of the same material, the reflective portion, which is a region on the capping layer where the absorbing portion is not formed, has a reflectivity of 50% or more for EUV light, the capping layer and the protective layer have a total film thickness of 3 nm or more, and the capping layer and the protective layer are resistant to hydrogen radicals.

[0014] According to one aspect of the present invention, a reflective mask having high hydrogen radical resistance and sufficient EUV reflectivity in the reflective portion can be provided. More specifically, according to one aspect of the present invention, a reflective photomask having excellent hydrogen radical resistance, reducing deterioration of transferability due to retardation in the reflective portion, and improving adhesion (interlayer adhesion) between the capping layer and the protective layer can be provided.

[0015] FIG. 1 is a schematic cross-sectional view showing the structure of a reflective mask according to an embodiment of the present invention. FIG. 2 is a graph showing the optical constants of each metal at the wavelength of EUV light. FIG. 3 is a conceptual diagram showing a hydrogen radical resistance evaluation method according to the present embodiment. FIG. 4 is a graph showing the EUV reflectivity of a reflective portion of a reflective mask according to an embodiment of the present invention. FIG. 5 is a schematic cross-sectional view showing the manufacturing process of a reflective mask according to an embodiment of the present invention. FIG. 6 is a schematic cross-sectional view showing the manufacturing process of a reflective mask according to an embodiment of the present invention. FIG. 7 is a schematic cross-sectional view showing the structure of a reflective mask according to an embodiment of the present invention.

[0016] The structure of a reflective mask according to an embodiment of the present invention will be described below with reference to the drawings. (Overall Structure) Fig. 1 is a schematic cross-sectional view showing the configuration of a coated reflective photomask (hereinafter simply referred to as a "reflective mask") 10. The reflective mask 10 is a reflective photomask for pattern transfer using extreme ultraviolet light as a light source. It includes a substrate 1, a reflective layer 2 formed on the substrate 1 and including a multilayer film that reflects EUV light, a capping layer 3 formed on the reflective layer 2, an absorbing portion 4 formed on a portion of the capping layer 3 that absorbs EUV light, and a protective layer 5 formed on the capping layer 3, the absorbing portion 4, and the side surfaces of the absorbing portion 4. The extinction coefficient k of the absorbing portion 4 for EUV light is 0.04 or greater. The capping layer 3 and the protective layer 5 are made of the same material, have a total thickness of 3 nm or greater, and are resistant to hydrogen radicals. The reflectivity of the reflective portion, which is the region of the capping layer 3 where the absorbing portion 4 is not formed, for EUV light is 50% or greater.

[0017] Each layer constituting the reflective mask 10 will be described in detail below. (Substrate) The substrate 1 according to this embodiment is, for example, a substrate with low thermal expansion. Specifically, a flat Si substrate, a synthetic quartz substrate, or the like can be used as the substrate. Alternatively, low thermal expansion glass with added titanium can be used as the substrate. As such, the substrate can be made of any material with a low thermal expansion coefficient, and is not limited to these materials.

[0018] (Multilayer Reflective Film) The multilayer reflective film (reflective layer) 2 according to this embodiment is a film (layer) formed on the substrate 1. This multilayer reflective film 2 is a film for reflecting EUV light (extreme ultraviolet light), which is exposure light, and is, for example, a multilayer reflective film formed by combining materials whose refractive indices for EUV light are significantly different from each other. As the multilayer reflective film 2, for example, a laminated film in which a layer containing Mo (molybdenum) and a layer containing Si (silicon) are laminated, or a film formed by repeatedly laminating a layer containing Mo (molybdenum) and a layer containing Be (beryllium) for about 40 periods is preferable.

[0019] (Capping Layer) The capping layer 3 according to this embodiment is a layer formed on the multilayer reflective film 2. The capping layer 3 is made of a material that is resistant to the dry etching that is performed when forming the absorbing portion 4. In other words, the capping layer 3 functions as an etching stopper that prevents damage to the multilayer reflective film 2 when the absorbing layer is etched to form the transfer pattern (absorbing portion 4).

[0020] The capping layer 3 is preferably formed of the same material as the protective layer 5 described later, and is a compound material that has hydrogen radical resistance and an extinction coefficient k of 0.035 or less. Therefore, as shown in FIG. 2, the capping layer 3 may be formed of, for example, ruthenium (Ru), yttrium (Y), niobium (Nb), titanium (Ti), zirconium (Zr), molybdenum (Mo), vanadium (V), tungsten (W), silicon oxide (SiO ２ ), yttrium oxide (Y ２ O ３ ), niobium oxide (Nb ２ O ５ ), titanium oxide (TiO ２ ), zirconium oxide (ZrO ２ ), molybdenum oxide (MoO ３ ), vanadium oxide (V ２ O ５ ), silicon oxide (SiO), tungsten oxide (WO ３), and more preferably a layer formed of a metal or metal oxide film containing at least one of ruthenium (Ru), silicon (Si), yttrium (Y), niobium (Nb), titanium (Ti), zirconium (Zr), molybdenum (Mo), vanadium (V), and tungsten (W).

[0021] Furthermore, the capping layer 3 preferably contains the above-mentioned elements at an atomic ratio of 50% or more. If the capping layer 3 contains the above-mentioned elements at an atomic ratio of 50% or more, the extinction coefficient k of the capping layer 3 for EUV can be easily set to 0.035 or less. The extinction coefficient k of the capping layer 3 may be adjusted by appropriately adjusting the content ratio of the materials forming the capping layer 3.

[0022] In this embodiment, the term "material having resistance to hydrogen radicals" refers to a compound material that undergoes a film loss of 1 nm or less in an environment of excited hydrogen radicals under conditions set to a distance of 18 mm using, for example, the apparatus shown in Fig. 3, a hydrogen flow rate of 100 sscm, and a 2.45 GHz MWP (Microwave Plasma), with the distance between electrodes 301 set to 18 mm. Also, the term "film (layer) having resistance to hydrogen radicals" refers to a film (layer) that undergoes a film loss of 1 nm or less in the above-mentioned hydrogen radical environment.

[0023] Furthermore, the extinction coefficient k of the capping layer 3 is preferably 0.035 or less for EUV light. If the extinction coefficient k of the capping layer 3 is 0.035 or less for EUV light, sufficient transparency can be obtained and deterioration of transferability due to retardation in the reflective portion can be reduced. Furthermore, in order to protect the multilayer reflective film 2, the thickness of the capping layer 3 as a remaining film after the formation of the absorbing portion 4 is preferably 1.0 nm or more, and more preferably 1.5 nm or more.

[0024] Furthermore, the film thickness of the capping layer 3 before patterning, i.e., the film thickness of the capping layer 3 in the photomask blank, is preferably 4.5 nm or less, and more preferably 3.5 nm or less, in order to suppress the film thickness of the absorbing portion 4. Furthermore, in order to reduce damage to the multilayer reflective film 2 due to patterning, it is more preferable that the remaining film thickness of the capping layer 3 be 1.5 nm or more.

[0025] (Absorbing Portion) The absorbing portion 4 according to this embodiment is desirably formed of a material with high EUV absorption rate in order to reduce the projection effect, and is desirably formed of an element or compound containing at least one material with k=0.040 or higher. The material forming the absorbing portion 4 is desirably, for example, an element or compound containing one or more elements selected from Te, Sb, Pt, I, Bi, Ir, Os, W, Re, Sn, In, Pd, Fe, Au, Hg, Ta, Ga, and Ni, and may contain non-metallic materials such as oxygen, nitrogen, and hydrogen.

[0026] Furthermore, it is preferable that the material forming the absorber 4 contains the above-mentioned metal elements at an atomic ratio of 50% or more. If the absorber 4 contains the above-mentioned metal elements at an atomic ratio of 50% or more, the extinction coefficient k of the absorber 4 can be easily set to 0.04 or more for EUV. Note that the extinction coefficient k of the absorber 4 may be adjusted by appropriately adjusting the content ratio of the materials forming the absorber 4.

[0027] The film thickness of the absorbing portion 4 may be in the range of 10 nm to 50 nm, more preferably in the range of 20 nm to 40 nm, and even more preferably in the range of 25 nm to 35 nm. If the film thickness of the absorbing portion 4 is within the above numerical range, EUV light can be effectively absorbed and the absorbing portion 4 can be made thin.

[0028] Furthermore, for the purpose of improving the pattern resolution of the absorbing portion 4, one or more layers of a hard mask (not shown) may be provided on the absorbing portion 4. The material of the hard mask is preferably a material containing at least one element such as Cr, Si, or Ta.

[0029] (Protective Layer) The protective layer 5 is a layer made of a material resistant to hydrogen radicals, and is a film formed on the capping layer 3 and on the surface and side surfaces of the absorbing part 4. The protective layer 5 is also made of the same material as the capping layer 3.

[0030] In the case of the reflective mask 10 according to this embodiment, the protective layer 5 is the outermost layer of the reflective mask 10, and therefore preferably does not obstruct the optical paths of the incident light and the reflected light. To prevent degradation of resolution due to the projection effect, the extinction coefficient k of the protective layer 5, which is the outermost layer, is preferably 0.035 or less. Furthermore, the thickness of the protective layer 5 is preferably 2.0 nm or more, more preferably 2.5 nm or more, in order to ensure uniform film formation on the exposed surface (surface) of the capping layer 3 and the exposed surfaces (surface and side surfaces) of the absorbing portion 4 and resistance to hydrogen radicals. Therefore, the total thickness of the capping layer 3 and the protective layer 5 is preferably 3.0 nm or more.

[0031] Furthermore, as the total thickness of the capping layer 3 and the protective layer 5 increases, the EUV light reflectivity of the reflective portion decreases and the influence of the projection effect of the absorbing portion 4 increases, so the total thickness is preferably 10 nm or less, and more preferably 8 nm or less. Note that Fig. 4 shows the result of the decrease in EUV light reflectivity of the reflective portion as the total thickness of the capping layer 3 and the protective layer 5 increases. Furthermore, in order to maintain a contrast that allows pattern transfer, it is preferable that the OD value of the absorbing portion 4 and the protective layer 5 as a whole is set to be 1 or more.

[0032] As described above, a compound material having hydrogen radical resistance and an extinction coefficient k of 0.035 or less is preferable as the material for forming the protective layer 5. Therefore, as shown in FIG. 2, the protective layer 5 is preferably made of, for example, ruthenium (Ru), yttrium (Y), niobium (Nb), titanium (Ti), zirconium (Zr), molybdenum (Mo), vanadium (V), tungsten (W), silicon oxide (SiO ２ ), yttrium oxide (Y ２ O ３ ), niobium oxide (Nb ２ O ５ ), titanium oxide (TiO ２ ), zirconium oxide (ZrO ２), molybdenum oxide (MoO ３ ), vanadium oxide (V ２ O ５ ), silicon oxide (SiO), tungsten oxide (WO ３ It is preferable that the layer is formed by containing at least one of ruthenium (Ru), silicon (Si), yttrium (Y), niobium (Nb), titanium (Ti), zirconium (Zr), molybdenum (Mo), vanadium (V), and tungsten (W), and it is more preferable that the layer is formed by a metal or metal oxide film containing at least one of ruthenium (Ru), silicon (Si), yttrium (Y), niobium (Nb), titanium (Ti), zirconium (Zr), molybdenum (Mo), vanadium (V), and tungsten (W).

[0033] Furthermore, the protective layer 5 preferably contains the above-mentioned elements at an atomic ratio of 50% or more. If the protective layer 5 contains the above-mentioned elements at an atomic ratio of 50% or more, the extinction coefficient k of the protective layer 5 with respect to EUV can be easily set to 0.035 or less. The extinction coefficient k of the protective layer 5 may be adjusted by appropriately adjusting the content ratio of the materials forming the protective layer 5.

[0034] 1, in the reflective mask 10 according to this embodiment, a back conductive film can be formed on the surface of the substrate 1 opposite to the surface on which the multilayer reflective film 2 is formed. The back conductive film is a film for fixing the reflective mask 10 by utilizing the principle of an electrostatic chuck when the mask is placed in an exposure machine.

[0035] (Method of Forming Protective Layer) When manufacturing the reflective mask 10 according to this embodiment, the protective layer 5 may be formed by atomic layer deposition using a gas containing at least one of ruthenium (Ru), silicon (Si), yttrium (Y), niobium (Nb), titanium (Ti), zirconium (Zr), molybdenum (Mo), vanadium (V), and tungsten (W). Atomic layer deposition allows for the formation of thin films in atomic layer units. Therefore, the protective layer 5 formed by this method has high film thickness uniformity and high shape conformability.

[0036] Furthermore, the reflectance of EUV light at the reflective portion, which is the region where the capping layer 3 and the protective layer 5 are stacked, is 50% or more. If the reflectance of EUV light at the reflective portion is 50% or more, excellent transferability can be obtained.

[0037] The protective layer 5 formed to cover the exposed surfaces of the capping layer 3 and the absorber 4 has a limited allowable thickness to prevent deterioration of transferability due to the protective layer 5, as described above, and the formed protective layer 5 is required to have a uniform thickness. Therefore, by forming the protective layer 5 using atomic layer deposition, which has excellent thickness uniformity and shape conformality, it is possible to manufacture a reflective mask 10 with high hydrogen radical resistance without deterioration of pattern transferability. Here, "uniform thickness" means that the thickness of the thinnest portion of the protective layer 5 formed on the capping layer 3 and on the surface and side surfaces of the absorber 4 is within a range of -2 nm and the thickness of the thickest portion is within a range of +2 nm of the average thickness of the protective layer 5 formed on the capping layer 3 and on the surface and side surfaces of the absorber 4. That is, in this embodiment, the thickness of the protective layer 5 formed on the surface of the absorber 4 is within a range of ±2 nm from the average thickness. Furthermore, the thickness of the protective layer 5 formed on the side surfaces of the absorber 4 is within a range of ±2 nm from the average thickness. Furthermore, the thickness of the protective layer 5 formed on the capping layer 3 is within a range of ±2 nm from the average thickness.

[0038] As described above, in the reflective mask 10 according to this embodiment, the protective layer 5, which has high hydrogen radical resistance, is formed by atomic layer deposition on the capping layer 3 and on the surfaces and side surfaces of the absorbing portion 4. The capping layer 3 is also made of a material that has high hydrogen radical resistance. Therefore, the reflective mask 10 can withstand long-term use.

[0039] Furthermore, the capping layer 3 and the protective layer 5 are each uniformly formed from a material with high EUV transmittance, which can suppress deterioration of transferability due to the formation of the capping layer 3 and the protective layer 5. Therefore, even when an absorber layer material with low hydrogen radical resistance is used, high pattern transfer accuracy can be achieved.

[0040] Furthermore, since the protective layer 5 is made of the same material as the capping layer 3, it is possible to reduce deterioration in transferability due to retardation in the reflective portion, which is an area on the capping layer 3 where the absorbing portion 4 is not formed. Furthermore, since the protective layer 5 is made of the same material as the capping layer 3, it is possible to improve adhesion (interlayer adhesion) between the capping layer 3 and the protective layer 5.

[0041] [Example 1] A reflective mask according to an example of the present invention will be described below with reference to figures and tables. As shown in Figure 5, a multilayer reflective film 12 was formed by stacking 40 layers of films each consisting of a pair of silicon (Si) and molybdenum (Mo) on a synthetic quartz substrate 11 having low thermal expansion. The thickness of the multilayer reflective film 12 was 280 nm.

[0042] Next, a capping layer 13 made of ruthenium (Ru) was deposited on the multilayer reflective film 12 as an intermediate film to a thickness of 2.5 nm. This resulted in a reflective layer (reflective portion) 16 comprising the multilayer reflective film 12 and the capping layer 13 being formed on the substrate 11. An absorbing portion 14 made of platinum (Pt) was deposited on the capping layer 13 to a thickness of 26 nm. Note that platinum (Pt), the material of the absorbing portion 14, has an extinction coefficient k of 0.04 or greater, which is higher than the extinction coefficient k of tantalum (Ta). Next, a backside conductive film 15 made of chromium nitride (CrN) was deposited to a thickness of 100 nm on the side of the substrate 11 where the multilayer reflective film 12 was not formed. A multi-target sputtering system was used to deposit each film on the substrate 11. The film thickness of each film was controlled by the sputtering time.

[0043] Next, a positive chemically amplified resist (SEBP9012, manufactured by Shin-Etsu Chemical Co., Ltd.) was formed on the absorbing portion 14 by spin coating to a film thickness of 120 nm, and baked at 110° C. for 10 minutes to form a resist film 17. Next, a predetermined pattern was written on the positive chemically amplified resist using an electron beam lithography machine (JBX3030, manufactured by JEOL Ltd.).

[0044] Thereafter, the resist was baked at 110° C. for 10 minutes, and then spray-developed (SFG3000, manufactured by Sigma Meltec Co., Ltd.) to form a resist pattern 17a as shown in FIG.

[0045] Next, using the resist pattern as an etching mask, the absorbing portion 14 was patterned by dry etching mainly using a chlorine-based gas to form an absorbing portion pattern 14a. Next, the remaining resist pattern 17a was peeled off. In this way, as shown in FIG. 7, an absorbing portion pattern 14a was formed in which the surface and side surfaces of the absorbing portion 14 were exposed. In this example, the absorbing portion pattern 14a was a line-and-space (LS) pattern with a line width of 64 nm.

[0046] The capping layer 13, which had a thickness of 2.5 nm, was reduced in thickness by 1.5 nm by the above-described patterning, so that the thickness of the capping layer 13 after patterning was 1 nm. A scanning probe microscope was used to measure the thickness.

[0047] Next, a protective layer 18 made of ruthenium (Ru) was formed on the exposed surface and side surfaces of the absorbing portion 14 and on the reflective layer 16 (capping layer 13) by atomic layer deposition using a gas containing ruthenium (Ru). The thickness of the protective layer 18 was adjusted so that the total thickness of the capping layer 13 and the protective layer 18 was 3 nm, i.e., so that the thickness of the protective layer 18 was 2 nm. The refractive index n of the formed protective layer 18 was 0.886, and the extinction coefficient k was 0.017. In this way, a reflective photomask 100 according to Example 1 (hereinafter also simply referred to as a "reflective mask") as shown in FIG. 8 was fabricated.

[0048] Next, the reflectance Rm of the multilayer reflective film region and the reflectance Ra of the absorbing film region were measured using a reflectance measuring device using EUV light for the absorbing portion 14 of Example 1. As a result, as shown in Table 1, it was found that the EUV reflectance of the multilayer reflective film region was set to 64.7%.

[0049] Example 2 An absorbing portion pattern 14a shown in FIG. 7 was formed using a method similar to that of Example 1. Next, a protective layer 18 made of ruthenium (Ru) was formed on the exposed surface and side surfaces of the absorbing portion 14 and on the reflective layer 16 (capping layer 13) by atomic layer deposition using a gas containing ruthenium (Ru). The thickness of the protective layer 18 was adjusted so that the total thickness of the capping layer 13 and the protective layer 18 was 10 nm. The refractive index n of the formed protective layer 18 was 0.886, and the extinction coefficient k was 0.017. In this way, a reflective photomask 100 according to Example 2 (hereinafter also simply referred to as a "reflective mask") as shown in FIG. 8 was fabricated.

[0050] Next, the reflectance Rm of the multilayer reflective film region and the reflectance Ra of the absorbing film region were measured using a reflectance measuring device using EUV light for the absorbing portion 14 of Example 2. As a result, as shown in Table 1, it was found that the EUV reflectance of the multilayer reflective film region was set to 50.6%.

[0051] Example 3 An absorbing portion pattern 14a shown in FIG. 7 was formed using a method similar to that of Example 1. Next, a protective layer 18 made of ruthenium (Ru) was formed on the exposed surface and side surfaces of the absorbing portion 14 and on the reflective layer 16 (capping layer 13) by atomic layer deposition using a gas containing ruthenium (Ru). The thickness of the protective layer 18 was adjusted so that the total thickness of the capping layer 13 and the protective layer 18 was 12 nm. The refractive index n of the formed protective layer 18 was 0.886, and the extinction coefficient k was 0.017. In this way, a reflective photomask 100 according to Example 3 (hereinafter also simply referred to as a "reflective mask") as shown in FIG. 8 was fabricated.

[0052] Next, the reflectance Rm of the multilayer reflective film region and the reflectance Ra of the absorbing film region were measured using a reflectance measuring device using EUV light for the absorbing portion 14 of Example 3. As a result, as shown in Table 1, it was found that the EUV reflectance of the multilayer reflective film region was set to 50.0%.

[0053] Example 4 An absorbing portion pattern 14a shown in FIG. 7 was formed in the same manner as in Example 1, except that the capping layer 13 was formed of yttrium (Y).

[0054] Next, a protective layer 18 made of yttrium (Y) was formed on the exposed surface and side surfaces of the absorbing portion 14 and on the reflective layer 16 (capping layer 13) by atomic layer deposition using a gas containing yttrium (Y). The thickness of the protective layer 18 was adjusted so that the total thickness of the capping layer 13 and the protective layer 18 was 4 nm. The refractive index n of the formed protective layer 18 was 0.974, and the extinction coefficient k was 0.003. In this way, a reflective photomask 100 according to Example 4 (hereinafter also simply referred to as a "reflective mask") as shown in FIG. 8 was fabricated.

[0055] Next, the reflectance Rm of the multilayer reflective film region and the reflectance Ra of the absorbing film region were measured using a reflectance measuring device using EUV light for the absorbing portion 14 of Example 4. As a result, as shown in Table 1, it was found that the EUV reflectance of the multilayer reflective film region was set to 63.0%.

[0056] Example 5 An absorbing portion pattern 14a shown in FIG. 7 was formed in the same manner as in Example 1, except that the capping layer 13 was formed of yttrium (Y).

[0057] Next, a protective layer 18 made of yttrium (Y) was formed on the exposed surface and side surfaces of the absorbing portion 14 and on the reflective layer 16 (capping layer 13) by atomic layer deposition using a gas containing yttrium (Y). The thickness of the protective layer 18 was adjusted so that the total thickness of the capping layer 13 and the protective layer 18 was 10 nm. The refractive index n of the formed protective layer 18 was 0.974, and the extinction coefficient k was 0.003. In this way, a reflective photomask 100 according to Example 5 (hereinafter also simply referred to as a "reflective mask") as shown in FIG. 8 was fabricated.

[0058] Next, the reflectance Rm of the multilayer reflective film region and the reflectance Ra of the absorbing film region were measured using a reflectance measuring device using EUV light for the absorbing portion 14 of Example 5. As a result, as shown in Table 1, it was found that the EUV reflectance of the multilayer reflective film region was set to 60.9%.

[0059] Example 6 An absorbing portion pattern 14a shown in FIG. 7 was formed in the same manner as in Example 1, except that the capping layer 13 was formed of yttrium (Y).

[0060] Next, a protective layer 18 made of yttrium (Y) was formed on the exposed surface and side surfaces of the absorbing portion 14 and on the reflective layer 16 (capping layer 13) by atomic layer deposition using a gas containing yttrium (Y). The thickness of the protective layer 18 was adjusted so that the total thickness of the capping layer 13 and the protective layer 18 was 13 nm. The refractive index n of the formed protective layer 18 was 0.974, and the extinction coefficient k was 0.003. In this way, a reflective photomask 100 according to Example 6 (hereinafter also simply referred to as a "reflective mask") as shown in FIG. 8 was fabricated.

[0061] Next, the reflectance Rm of the multilayer reflective film region and the reflectance Ra of the absorbing film region were measured using a reflectance measuring device using EUV light for the absorbing portion 14 of Example 6. As a result, as shown in Table 1, it was found that the EUV reflectance of the multilayer reflective film region was set to 58.5%.

[0062] Example 7 An absorbing portion pattern 14a shown in FIG. 7 was formed in the same manner as in Example 1, except that the capping layer 13 was formed of niobium (Nb).

[0063] Next, a protective layer 18 made of niobium (Nb) was formed on the exposed surface and side surfaces of the absorbing portion 14 and on the reflective layer 16 (capping layer 13) by atomic layer deposition using a gas containing niobium (Nb). The thickness of the protective layer 18 was adjusted so that the total thickness of the capping layer 13 and the protective layer 18 was 4 nm. The refractive index n of the formed protective layer 18 was 0.934, and the extinction coefficient k was 0.005. In this way, a reflective photomask 100 according to Example 7 (hereinafter also simply referred to as a "reflective mask") as shown in FIG. 8 was fabricated.

[0064] Next, the reflectance Rm of the multilayer reflective film region and the reflectance Ra of the absorbing film region were measured using a reflectance measuring device using EUV light for the absorbing portion 14 of Example 7. As a result, as shown in Table 1, it was found that the EUV reflectance of the multilayer reflective film region was set to 64.5%.

[0065] Example 8 The absorbing portion pattern 14a shown in FIG. 7 was formed in the same manner as in Example 1, except that the capping layer 13 was formed of niobium (Nb).

[0066] Next, a protective layer 18 made of niobium (Nb) was formed on the exposed surface and side surfaces of the absorbing portion 14 and on the reflective layer 16 (capping layer 13) by atomic layer deposition using a gas containing niobium (Nb). The thickness of the protective layer 18 was adjusted so that the total thickness of the capping layer 13 and the protective layer 18 was 12 nm. The refractive index n of the formed protective layer 18 was 0.934, and the extinction coefficient k was 0.005. In this way, a reflective photomask 100 according to Example 8 (hereinafter also simply referred to as a "reflective mask") as shown in FIG. 8 was fabricated.

[0067] Next, the reflectance Rm of the multilayer reflective film region and the reflectance Ra of the absorbing film region were measured using a reflectance measuring device using EUV light for the absorbing portion 14 of Example 8. As a result, as shown in Table 1, it was found that the EUV reflectance of the multilayer reflective film region was set to 59.5%.

[0068] Example 9: The capping layer 13 is made of niobium oxide (Nb ２ O ５7 was formed in the same manner as in Example 1, except that the absorbing portion pattern 14a shown in FIG.

[0069] Next, niobium oxide (Nb) is deposited on the exposed surface and side surfaces of the absorber 14 and the reflective layer 16 (capping layer 13) by atomic layer deposition using a gas containing niobium (Nb) and oxygen (O). ２ O ５ ) was deposited. At this time, the thickness of the protective layer 18 was adjusted so that the total thickness of the capping layer 13 and the protective layer 18 was 3 nm. The refractive index n of the deposited protective layer 18 was 0.954, and the extinction coefficient k was 0.010. In this way, a reflective photomask 100 according to Example 9 (hereinafter also simply referred to as a "reflective mask") as shown in FIG. 8 was produced.

[0070] Next, the reflectance Rm of the multilayer reflective film region and the reflectance Ra of the absorbing film region were measured using a reflectance measuring device using EUV light for the absorbing portion 14 of Example 9. As a result, as shown in Table 1, it was found that the EUV reflectance of the multilayer reflective film region was set to 64.7%.

[0071] Example 10: The capping layer 13 is made of niobium oxide (Nb ２ O ５ 7 was formed in the same manner as in Example 1, except that the absorbing portion pattern 14a shown in FIG.

[0072] Next, niobium oxide (Nb) is deposited on the exposed surface and side surfaces of the absorber 14 and the reflective layer 16 (capping layer 13) by atomic layer deposition using a gas containing niobium (Nb) and oxygen (O). ２ O ５ ) was deposited. At this time, the thickness of the protective layer 18 was adjusted so that the total thickness of the capping layer 13 and the protective layer 18 was 12 nm. The refractive index n of the deposited protective layer 18 was 0.954, and the extinction coefficient k was 0.010. In this way, a reflective photomask 100 according to Example 10 (hereinafter also simply referred to as a "reflective mask") as shown in FIG. 8 was produced.

[0073] Next, the reflectance Rm of the multilayer reflective film region (reflective portion) and the reflectance Ra of the absorbing film region (absorbing portion) were measured using a reflectance measurement device using EUV light for the absorbing portion 14 of Example 10. As a result, as shown in Table 1, it was found that the EUV light reflectance of the reflective portion, which is the region on the capping layer 13 where the absorbing portion 14 is not formed, was set to 51.7%.

[0074] Example 11 An absorbing portion pattern 14a shown in FIG. 7 was formed in the same manner as in Example 1, except that the capping layer 13 was formed of vanadium (V).

[0075] Next, a protective layer 18 made of vanadium (V) was formed on the exposed surface and side surfaces of the absorbing portion 14 and on the reflective layer 16 (capping layer 13) by atomic layer deposition using a gas containing vanadium (V). The thickness of the protective layer 18 was adjusted so that the total thickness of the capping layer 13 and the protective layer 18 was 4 nm. The refractive index n of the formed protective layer 18 was 0.943, and the extinction coefficient k was 0.025. In this way, a reflective photomask 100 according to Example 11 (hereinafter also simply referred to as a "reflective mask") as shown in FIG. 8 was fabricated.

[0076] Next, the reflectance Rm of the multilayer reflective film region and the reflectance Ra of the absorbing film region were measured using a reflectance measuring device using EUV light for the absorbing portion 14 of Example 11. As a result, as shown in Table 1, it was found that the EUV reflectance of the reflective portion was set to 56.7%.

[0077] Example 12 The absorbing portion pattern 14a shown in FIG. 7 was formed in the same manner as in Example 1, except that the capping layer 13 was formed of chromium (Cr).

[0078] Next, a protective layer 18 made of chromium (Cr) was formed on the exposed surface and side surfaces of the absorbing portion 14 and on the reflective layer 16 (capping layer 13) by atomic layer deposition using a gas containing chromium (Cr). The thickness of the protective layer 18 was adjusted so that the total thickness of the capping layer 13 and the protective layer 18 was 3 nm. The refractive index n of the formed protective layer 18 was 0.933, and the extinction coefficient k was 0.039. In this way, a reflective photomask 100 according to Example 12 (hereinafter also simply referred to as a "reflective mask") as shown in FIG. 8 was fabricated.

[0079] Next, the reflectance Rm of the multilayer reflective film region and the reflectance Ra of the absorbing film region were measured using a reflectance measuring device using EUV light for the absorbing portion 14 of Example 12. As a result, as shown in Table 1, it was found that the EUV reflectance of the reflective portion was set to 59.0%.

[0080] Example 13: The capping layer 13 was formed using chromium oxide (Cr ２ O ３ 7 was formed in the same manner as in Example 1, except that the absorbing portion pattern 14a shown in FIG.

[0081] Next, chromium oxide (CrO) is deposited on the exposed surface and side surfaces of the absorber 14 and the reflective layer 16 (capping layer 13) by atomic layer deposition using a gas containing chromium (Cr) and oxygen (O). ２ O ３ ) was deposited. At this time, the thickness of the protective layer 18 was adjusted so that the total thickness of the capping layer 13 and the protective layer 18 was 4 nm. The refractive index n of the deposited protective layer 18 was 0.928, and the extinction coefficient k was 0.036. In this way, a reflective photomask 100 according to Example 13 (hereinafter also simply referred to as a "reflective mask") as shown in FIG. 8 was produced.

[0082] Next, the reflectance Rm of the multilayer reflective film region and the reflectance Ra of the absorbing film region were measured using a reflectance measuring device using EUV light for the absorbing portion 14 of Example 13. As a result, as shown in Table 1, it was found that the EUV reflectance of the reflective portion was set to 54.2%.

[0083] Example 14: The capping layer 13 was formed using silicon oxide (SiO ２ 7 was formed in the same manner as in Example 1, except that the absorbing portion pattern 14a shown in FIG.

[0084] Next, silicon oxide (SiO ) was deposited on the exposed surface and side surfaces of the absorber 14 and the reflective layer 16 (capping layer 13) by atomic layer deposition using a gas containing silicon (Si) and oxygen (O). ２ ) was deposited. At this time, the thickness of the protective layer 18 was adjusted so that the total thickness of the capping layer 13 and the protective layer 18 was 3 nm. The refractive index n of the deposited protective layer 18 was 0.974, and the extinction coefficient k was 0.013. In this way, a reflective photomask 100 according to Example 14 (hereinafter also simply referred to as a "reflective mask") as shown in FIG. 8 was produced.

[0085] Next, the reflectance Rm of the multilayer reflective film region and the reflectance Ra of the absorbing film region were measured using a reflectance measuring device for EUV light for the absorbing portion 14 of Example 14. As a result, as shown in Table 1, it was found that the EUV reflectance of the reflective portion was set to 61.5%.

[0086] Example 15: The capping layer 13 was formed using silicon oxide (SiO ２ 7 was formed in the same manner as in Example 1, except that the absorbing portion pattern 14a shown in FIG.

[0087] Next, silicon oxide (SiO ) was deposited on the exposed surface and side surfaces of the absorber 14 and the reflective layer 16 (capping layer 13) by atomic layer deposition using a gas containing silicon (Si) and oxygen (O). ２ ) was deposited. At this time, the thickness of the protective layer 18 was adjusted so that the total thickness of the capping layer 13 and the protective layer 18 was 10 nm. The refractive index n of the deposited protective layer 18 was 0.974, and the extinction coefficient k was 0.013. In this way, a reflective photomask 100 according to Example 15 (hereinafter also simply referred to as a "reflective mask") as shown in FIG. 8 was produced.

[0088] Next, the reflectance Rm of the multilayer reflective film region and the reflectance Ra of the absorbing film region were measured using a reflectance measuring device using EUV light for the absorbing portion 14 of Example 15. As a result, as shown in Table 1, it was found that the EUV reflectance of the reflective portion was set to 52.0%.

[0089] Comparative Example 1 The absorbing portion pattern 14a shown in FIG.

[0090] Next, a protective layer 18 made of ruthenium (Ru) was formed on the exposed surface and side surfaces of the absorbing portion 14 and on the reflective layer 16 (capping layer 13) by atomic layer deposition using a gas containing ruthenium (Ru). The thickness of the protective layer 18 was adjusted so that the total thickness of the capping layer 13 and the protective layer 18 was 2 nm. The refractive index n of the formed protective layer 18 was 0.886, and the extinction coefficient k was 0.017. In this way, a reflective photomask 100 according to Comparative Example 1 (hereinafter also simply referred to as a "reflective mask") as shown in FIG. 8 was fabricated.

[0091] Next, the reflectance Rm of the multilayer reflective film region and the reflectance Ra of the absorbing film region were measured using a reflectance measuring device using EUV light for the absorbing portion 14 of Comparative Example 1. As a result, as shown in Table 1, it was found that the EUV reflectance of the reflective portion was set to 64.2%.

[0092] Comparative Example 2: The capping layer 13 was formed using niobium oxide (Nb ２ O ５ 7 was formed in the same manner as in Example 1, except that the absorbing portion pattern 14a shown in FIG.

[0093] Next, niobium oxide (Nb) is deposited on the exposed surface and side surfaces of the absorber 14 and the reflective layer 16 (capping layer 13) by atomic layer deposition using a gas containing niobium (Nb) and oxygen (O). ２ O ５) was deposited. At this time, the thickness of the protective layer 18 was adjusted so that the total thickness of the capping layer 13 and the protective layer 18 was 2 nm. The refractive index n of the deposited protective layer 18 was 0.954, and the extinction coefficient k was 0.010. In this way, a reflective photomask 100 according to Comparative Example 2 (hereinafter also simply referred to as a "reflective mask") as shown in FIG. 8 was produced.

[0094] Next, the reflectance Rm of the multilayer reflective film region and the reflectance Ra of the absorbing film region were measured using a reflectance measuring device using EUV light for the absorbing portion 14 of Comparative Example 2. As a result, as shown in Table 1, it was found that the EUV reflectance of the reflective portion was set to 63.2%.

[0095] Comparative Example 3 An absorbing portion pattern 14a shown in FIG. 7 was formed in the same manner as in Example 1, except that the capping layer 13 was formed of vanadium (V).

[0096] Next, a protective layer 18 made of vanadium (V) was formed on the exposed surface and side surfaces of the absorbing portion 14 and on the reflective layer 16 (capping layer 13) by atomic layer deposition using a gas containing vanadium (V). The thickness of the protective layer 18 was adjusted so that the total thickness of the capping layer 13 and the protective layer 18 was 11 nm. The refractive index n of the formed protective layer 18 was 0.943, and the extinction coefficient k was 0.025. In this way, a reflective photomask 100 according to Comparative Example 3 (hereinafter also simply referred to as a "reflective mask") as shown in FIG. 8 was produced.

[0097] Next, the reflectance Rm of the multilayer reflective film region and the reflectance Ra of the absorbing film region were measured using a reflectance measuring device using EUV light for the absorbing portion 14 of Comparative Example 3. As a result, as shown in Table 1, it was found that the EUV reflectance of the reflective portion was set to 42.0%.

[0098] Comparative Example 4: The capping layer 13 was formed using chromium oxide (Cr ２ O ３ 7 was formed in the same manner as in Example 1, except that the absorbing portion pattern 14a shown in FIG.

[0099] Next, chromium oxide (CrO) is deposited on the exposed surface and side surfaces of the absorber 14 and the reflective layer 16 (capping layer 13) by atomic layer deposition using a gas containing chromium (Cr) and oxygen (O). ２ O ３ ) was deposited. At this time, the thickness of the protective layer 18 was adjusted so that the total thickness of the capping layer 13 and the protective layer 18 was 7 nm. The refractive index n of the deposited protective layer 18 was 0.928, and the extinction coefficient k was 0.036. In this way, a reflective photomask 100 according to Comparative Example 4 (hereinafter also simply referred to as a "reflective mask") as shown in FIG. 8 was produced.

[0100] Next, the reflectance Rm of the multilayer reflective film region and the reflectance Ra of the absorbing film region were measured using a reflectance measuring device using EUV light for the absorbing portion 14 of Comparative Example 4. As a result, as shown in Table 1, it was found that the EUV reflectance of the reflective portion was set to 37.3%.

[0101] Comparative Example 5 An absorbing portion pattern 14a shown in FIG. 7 was formed in the same manner as in Example 1, except that the capping layer 13 was formed of chromium (Cr).

[0102] Next, a protective layer 18 made of chromium (Cr) was formed on the exposed surface and side surfaces of the absorbing portion 14 and on the reflective layer 16 (capping layer 13) by atomic layer deposition using a gas containing chromium (Cr). The thickness of the protective layer 18 was adjusted so that the total thickness of the capping layer 13 and the protective layer 18 was 7 nm. The refractive index n of the formed protective layer 18 was 0.933, and the extinction coefficient k was 0.039. In this way, a reflective photomask 100 according to Comparative Example 5 (hereinafter also simply referred to as a "reflective mask") as shown in FIG. 8 was produced.

[0103] Next, the reflectance Rm of the multilayer reflective film region and the reflectance Ra of the absorbing film region were measured using a reflectance measuring device using EUV light for the absorbing portion 14 of Comparative Example 5. As a result, as shown in Table 1, it was found that the EUV reflectance of the reflective portion was set to 35.8%.

[0104] In the above-described examples and comparative examples, the thickness of each of the capping layer 13 and the protective layer 18 was measured using a transmission electron microscope.

[0105] [EUV Reflectance] In this example, if the EUV reflectance was 50% or more, it was determined to be acceptable since it had sufficient transferability.

[0106] [Hydrogen Radical Resistance] Using a 2.45 GHz MWP (Microwave Plasma), hydrogen was excited at a flow rate of 100 sscm, and the prepared reflective photomask was placed on one of the electrodes with an inter-electrode distance of 18 mm. The change in thickness of the absorbing film after hydrogen radical treatment was confirmed using an atomic force microscope (AFM) and evaluated using the following three levels: ◎, ○, and ×. The measurement was performed using a LS pattern with a line width of 200 nm. In this example, "◎" and "○" were considered to be acceptable.

[0107] <Evaluation criteria> ⊚: No change in film thickness was observed due to hydrogen radicals ◯: A slight change in film thickness was observed due to hydrogen radicals ×: A change in film thickness was observed due to hydrogen radicals The above evaluation results are shown in Table 1.

[0108]

[0109] [Adhesion (Interlayer Adhesion)] In this example, the capping layer 13 and the protective layer 18 are formed of the same material. Therefore, the capping layer 13 and the protective layer 18 have such adhesion that they can be considered to be one layer (single layer). Therefore, the adhesion (interlayer adhesion) between the capping layer 13 and the protective layer 18 in this example does not pose any problems in use, and was therefore evaluated as passed.

[0110] As shown in Table 1, from the evaluation results of Examples 1 to 15 and Comparative Examples 1 to 5, a reflective photomask in which the extinction coefficient k of the absorbing portion 14 is 0.04 or more for EUV, the capping layer 13 and the protective layer 18 are formed of the same material, the reflectivity of the reflective portion (multilayer reflective film region) on the capping layer 13 where the absorbing portion 14 is not formed is 50% or more, and further the total film thickness of the capping layer 13 and the protective layer 18 is 3 nm or more, and the capping layer 13 and the protective layer 18 are resistant to hydrogen radicals, can provide a reflective photomask that has excellent hydrogen radical resistance, reduces deterioration of transferability due to phase difference in the reflective portion, and can improve adhesion (interlayer adhesion) between the capping layer 13 and the protective layer 18.

[0111] For example, the present invention can be configured as follows: (1) A reflective photomask comprising: a substrate; a reflective layer formed on the substrate and including a multilayer film that reflects EUV light; a capping layer formed on the reflective layer; an absorbing portion formed on a portion of the capping layer that absorbs EUV light; and a protective layer formed on the capping layer, on the absorbing portion, and on side surfaces of the absorbing portion, wherein the absorbing portion has an extinction coefficient k of 0.04 or more for EUV light, the capping layer and the protective layer are formed of the same material, a reflective portion that is a region on the capping layer where the absorbing portion is not formed has a reflectivity of 50% or more for EUV light, the capping layer and the protective layer have a total film thickness of 3 nm or more, and the capping layer and the protective layer are resistant to hydrogen radicals. (2) The reflective photomask according to (1) above, wherein the capping layer and the protective layer each have an extinction coefficient k of 0.035 or less for EUV light. (3) The reflective photomask according to (1) or (2), wherein the total thickness of the capping layer and the protective layer is 10 nm or less. (4) The reflective photomask according to any one of (1) to (3), wherein the capping layer and the protective layer are each formed of a metal or metal oxide film containing at least one of ruthenium (Ru), silicon (Si), yttrium (Y), niobium (Nb), titanium (Ti), zirconium (Zr), molybdenum (Mo), vanadium (V), and tungsten (W).

[0112] The reflective mask according to the present invention can be suitably used to form fine patterns by EUV exposure in the manufacturing process of semiconductor integrated circuits and the like.

[0113] DESCRIPTION OF SYMBOLS 1...Substrate 2...Multilayer reflective film (reflective layer) 3...Capping layer 4...Absorbing portion 5...Protective layer 10...Reflective mask 11...Substrate 12...Multilayer reflective film (reflective layer) 13...Capping layer 14...Absorbing portion 14a...Absorbing portion pattern 15...Back surface conductive film 16...Reflecting portion (reflective layer) 17...Resist film 17a...Resist pattern 18...Protective layer 100...Reflective mask 300...Chamber 301...Electrode 302...Sample

Claims

1. A reflective photomask comprising a substrate, a reflective layer formed on the substrate and including a multilayer film that reflects EUV light, a capping layer formed on the reflective layer, an absorption portion formed on a part of the capping layer and absorbing EUV light, and a protective layer formed on the capping layer, on the absorption portion, and on the side surface of the absorption portion, wherein an attenuation coefficient k of the absorption portion is 0.04 or more with respect to EUV light, the capping layer and the protective layer are formed of the same material, a reflectance of EUV light of a reflective portion, which is a region where the absorption portion is not formed on the capping layer, is 50% or more, a total film thickness of the capping layer and the protective layer is 3 nm or more, and the capping layer and the protective layer have resistance to hydrogen radicals.

2. The reflective photomask according to claim 1, wherein an attenuation coefficient k of each of the capping layer and the protective layer is 0.035 or less with respect to EUV light.

3. The reflective photomask according to claim 1, wherein a total film thickness of the capping layer and the protective layer is 10 nm or less.

4. The reflective photomask according to any one of claims 1 to 3, wherein the capping layer and the protective layer are each formed of a metal or a metal oxide film containing at least one of ruthenium (Ru), silicon (Si), yttrium (Y), niobium (Nb), titanium (Ti), zirconium (Zr), molybdenum (Mo), vanadium (V), and tungsten (W).

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