Reflective photomask

Abstract

The present application aims to provide a reflective photomask having excellent hydrogen radical resistance, capable of reducing deterioration of transferability caused by phase difference of a reflection portion, and capable of improving adhesion of a cover layer and a protective layer (interlayer adhesion). The reflective mask (10) according to the present embodiment includes a substrate (1), a multilayer reflection film (2), a cover layer (3), an absorption portion (4), and a protective layer (5) formed on the cover layer (3), on the absorption portion (4), and on the side surface of the absorption portion (4), the absorption portion (4) has an extinction coefficient k of 0.04 or more for EUV light, the cover layer (3) and the protective layer (5) are formed of the same material, the reflectance of a reflection portion, which is a region of the cover layer (3) where the absorption portion (4) is not formed, with respect to EUV light is 50% or more, the total film thickness of the cover layer (3) and the protective layer (5) is 3 nm or more, and the cover layer (3) and the protective layer (5) have hydrogen radical resistance.

Description

Technical Field

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

[0002] In semiconductor device manufacturing processes, as semiconductor devices become increasingly miniaturized, the requirements for miniaturization in photolithography technology also increase. The minimum resolution size of the transferred pattern in photolithography is highly dependent on the wavelength of the exposure light source; the shorter the wavelength, the smaller the minimum resolution size can be. Therefore, the exposure light source has been replaced from the previous 193nm ArF excimer laser to light in the EUV (Extreme Ultra Violet) region with a wavelength of 13.5nm.

[0003] In the EUV region, light is absorbed by most materials at a high proportion. Therefore, reflective photomasks are used as photomasks for EUV exposure (e.g., see Patent Document 1). Patent Document 1 discloses an EUV photomask that is obtained by forming a reflective layer on a glass substrate, consisting of alternating layers of molybdenum (Mo) and silicon (Si), forming a light-absorbing layer with tantalum (Ta) as the main component on the reflective layer, and forming a pattern on the light-absorbing layer.

[0004] Furthermore, as mentioned earlier, EUV lithography cannot use refractive optical systems that utilize light transmission. Therefore, the optical system components of the exposure machine are not lenses, but reflective (mirrors). Consequently, there is a problem that the incident light incident on the reflective photomask (EUV mask) and the reflected light reflected at the EUV mask cannot be designed to be coaxial. Typically, in EUV lithography, the following method is used: the light is incident with its axis tilted 6 degrees from the vertical direction of the EUV mask, and the reflected light, which is reflected at a negative 6-degree angle, is guided to the semiconductor substrate.

[0005] Thus, in EUV lithography, due to the tilting of the optical axis by the mirror, a problem sometimes occurs known as the "projection effect," in which EUV light incident on the EUV mask casts shadows on the mask pattern (patterned light-absorbing layer) of the EUV mask.

[0006] In existing EUV mask preforms, a tantalum (Ta)-based film with a thickness of 60-90 nm is used as the light-absorbing layer. When using an EUV mask fabricated using this preform for pattern transfer exposure, 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 edges where the mask pattern becomes shadowed. This can sometimes lead to increased edge roughness of the transferred pattern on the semiconductor substrate and the inability to achieve the target line width, resulting in deteriorated transfer performance.

[0007] Therefore, research has been conducted on reflective photomask preforms in which the light-absorbing layer is changed from tantalum (Ta) to a material with high absorption (extinction coefficient) for EUV light, or by incorporating a material with high absorption into tantalum (Ta). For example, Patent Document 1 describes a reflective photomask preform in which the light-absorbing layer is composed of a material containing at least 50 atomic percent (at%) Ta as the main component and 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.

[0008] Furthermore, to protect the multilayer film, a cover film is provided on the reflective layer composed of the multilayer film. As shown in Patent Document 2, the cover film is usually a film that is nearly transparent to EUV light, such as Ru, in order to prevent a decrease in EUV reflectivity. With such a configuration, although the reflective layer is protected during pattern formation, the Ru of the cover layer itself is damaged, and since it is formed as a thin film, most of it only leaves 1 to 2 nm of film. When using a photomask in this state, there is a possibility of device contamination due to peeling off of the cover film and damage to the reflective layer due to exposure of the reflective layer.

[0009] Furthermore, it is known that mirrors can be contaminated by byproducts (such as Sn) and carbon caused by EUV irradiation. As these contaminants accumulate on the mirror, the reflectivity of the mirror surface decreases, thereby reducing the throughput of the photolithography apparatus. To address this problem, Patent Document 3 discloses a method for removing contaminants from the mirror by generating hydrogen radicals within the apparatus and reacting these hydrogen radicals with the contaminants. As mentioned earlier, the materials used for reflective photomask preforms and reflective photomasks require high resistance to hydrogen radicals.

[0010] However, among materials with high absorption of EUV light, there are also materials with low resistance to hydrogen radicals. Reflective masks formed from materials with low resistance to hydrogen radicals have the problem of not being able to withstand long-term use.

[0011] It should be noted that, in order to protect the absorption layer (light absorption layer) and the cover layer, as shown in Patent Document 4, the method of using a coating film to cover the processed mask pattern is considered effective.

[0012] However, in methods that use a coating to cover a mask pattern, if the cover layer and the protective layer of the reflective part are made of different materials, the phase difference may adversely affect the transfer performance. Furthermore, due to the presence of material interfaces, hydrogen may accumulate at the interfaces, potentially causing peeling. Moreover, forming a protective film made of different materials on a damaged film (cover layer) may result in peeling depending on the adhesion between the materials.

[0013] Existing technical documents Patent documents Patent Document 1: Japanese Patent No. 4926523 Patent Document 2: Japanese Patent No. 5803919 Patent Document 3: Japanese Patent Application Publication No. 2011-530823 Patent Document 4: Japanese Patent Application Publication No. 2021-071685 Summary of the Invention

[0014] Technical issues The object of this invention is to protect the capping layer, which may be damaged, while improving resistance to hydrogen radicals by forming a protective film during the fabrication of a reflective photomask. Furthermore, by forming both the capping and protective layers from the same material, the adverse effects of phase difference in the reflective portion on transferability are suppressed, and problems such as adhesion issues caused by forming films from different materials are resolved. In other words, the object of this invention is to provide a reflective photomask that exhibits excellent resistance to hydrogen radicals, reduces the deterioration of transferability caused by phase difference in the reflective portion, and improves the adhesion (interlayer adhesion) between the capping and protective layers.

[0015] Technical solution According to one aspect of the present invention, a reflective photomask comprises: a substrate; a reflective layer formed on the substrate and comprising a multilayer film that reflects EUV light; a capping layer formed on the reflective layer; an absorber formed on a portion of the capping layer and absorbing EUV light; and a protective layer formed on the capping layer, on the absorber, and on the side surface of the absorber, wherein the absorber 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 of the capping layer where the absorber is not formed has a reflectivity of 50% or more for EUV light, the total film thickness of the capping layer and the protective layer is 3 nm or more, and the capping layer and the protective layer are resistant to hydrogen radicals.

[0016] Technical effect According to one aspect of the present invention, a reflective photomask with high hydrogen radical resistance and sufficient EUV reflectivity of the reflective portion can be provided. More specifically, according to one aspect of the present invention, a reflective photomask with excellent hydrogen radical resistance, capable of reducing the deterioration of transferability caused by phase difference of the reflective portion, and capable of improving the adhesion (interlayer adhesion) between the capping layer and the protective layer can be provided. Attached Figure Description

[0017] Figure 1 This is a schematic cross-sectional view showing the structure of a reflective mask according to an embodiment of the present invention.

[0018] Figure 2 It is a chart showing the optical constants of various metals at the wavelength of EUV light.

[0019] Figure 3 This is a conceptual diagram illustrating the hydrogen radical tolerance evaluation method according to this embodiment.

[0020] Figure 4 This is a graph showing the EUV reflectivity of the reflective portion of a reflective mask according to an embodiment of the present invention.

[0021] Figure 5 This is a schematic cross-sectional view illustrating the manufacturing process of a reflective mask according to an embodiment of the present invention.

[0022] Figure 6 This is a schematic cross-sectional view illustrating the manufacturing process of a reflective mask according to an embodiment of the present invention.

[0023] Figure 7 This is a schematic cross-sectional view illustrating the manufacturing process of a reflective mask according to an embodiment of the present invention.

[0024] Figure 8 This is a schematic cross-sectional view showing the structure of a reflective mask according to an embodiment of the present invention.

[0025] Symbol Explanation 1...Substrate 2…Multi-layer reflective film (reflective layer) 3...Covering layer 4… Absorption section 5…protective layer 10…Reflective Mask 11...Substrate 12… Multilayer reflective film (reflective layer) 13...overlay 14…Absorption section 14a…Absorbing section pattern 15... Backside conductive film 16…Reflective section (reflective layer) 17…Resist film 17a…Resist pattern 18…protective layer 100…reflective mask 300... chambers 301...electrode 302...sample Detailed Implementation

[0026] Hereinafter, the structure of a reflective mask according to an embodiment of the present invention will be described with reference to the accompanying drawings.

[0027] (Overall structure) Figure 1 This is a schematic cross-sectional view showing the structure of a reflective photomask (hereinafter also referred to as "reflective mask") 10 with a coating.

[0028] The reflective photomask 10 is a reflective photomask for pattern transfer using extreme ultraviolet (EUV) light as a light source. It comprises: a substrate 1; a reflective layer 2 formed on the substrate 1 and including a multilayer film reflecting 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 and absorbing EUV light; and a protective layer 5 formed on the capping layer 3, the absorbing portion 4, and the sides of the absorbing portion 4. Furthermore, the extinction coefficient k of the absorbing portion 4 for EUV light is 0.04 or higher. Additionally, the capping layer 3 and the protective layer 5 are formed of the same material, have a total film thickness of 3 nm or more, and are resistant to hydrogen radicals. Moreover, the reflective portion of the capping layer 3 where the absorbing portion 4 is not formed has a reflectivity of 50% or higher for EUV light.

[0029] The layers constituting the reflective mask 10 will be described in detail below.

[0030] (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. Furthermore, a low thermal expansion glass with added titanium can be used as the substrate. Thus, the substrate is not limited to any material with a low coefficient of thermal expansion.

[0031] (Multi-layer 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 used to reflect EUV light (extreme ultraviolet light) as exposure light, and is, for example, a multilayer reflective film formed by combining materials with significantly different refractive indices for EUV light. As the multilayer reflective film 2, a preferred example is a film formed by repeatedly stacking a layer containing Mo (molybdenum) and a layer containing Si (silicon), or a layer containing Mo (molybdenum) and a layer containing Be (beryllium) for approximately 40 cycles.

[0032] (Covering layer) According to this embodiment, the cover layer 3 is a layer formed on the multilayer reflective film 2. The cover layer 3 is formed of a material resistant to dry etching during the formation of the absorption portion 4. That is, when the absorption layer is etched to form a transfer pattern (absorption portion 4), the cover layer 3 functions as an etching barrier layer to prevent damage to the multilayer reflective film 2.

[0033] The capping layer 3 is a layer formed of the same material as the protective layer 5 described later; it can be a layer formed of a compound material that has hydrogen radical resistance and an extinction coefficient k of 0.035 or less. Therefore, as... Figure 2 As shown, the capping layer 3 is preferably a layer formed by, for example, containing at least one of ruthenium (Ru), yttrium (Y), niobium (Nb), titanium (Ti), zirconium (Zr), molybdenum (Mo), vanadium (V), tungsten (W), silicon oxide (SiO2), yttrium oxide (Y2O3), niobium oxide (Nb2O5), titanium oxide (TiO2), zirconium oxide (ZrO2), molybdenum oxide (MoO3), vanadium oxide (V2O5), silicon oxide (SiO), and tungsten oxide (WO3), and more preferably a layer 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).

[0034] Furthermore, the capping layer 3 preferably contains 50% or more of the aforementioned elements in terms of atomic percentage. If the capping layer 3 contains 50% or more of the aforementioned elements in terms of atomic percentage, it is easy to set the extinction coefficient k of the capping layer 3 for EUV to be 0.035 or less.

[0035] It should be noted that the extinction coefficient k of the capping layer 3 can be adjusted by appropriately adjusting the content ratio of the material forming the capping layer 3.

[0036] In this embodiment, "materials with hydrogen radical resistance" refers to, for example, materials using... Figure 3 The apparatus shown is used to generate a compound material with a film loss of less than 1 nm under hydrogen radical conditions excited by a hydrogen free radical environment with a hydrogen flow rate of 100 sscm and a distance of 18 mm between electrodes 301 using a 2.45 GHz Micro Wave Plasma (MWP). Furthermore, "a film (layer) resistant to hydrogen free radicals" refers to a film (layer) with a film loss of less than 1 nm under the aforementioned hydrogen free radical environment.

[0037] Furthermore, the extinction coefficient k of the cover layer 3 for EUV light is preferably 0.035 or less. If the extinction coefficient k of the cover layer 3 for EUV light is 0.035 or less, sufficient transparency can be obtained, and the deterioration of transferability caused by the phase difference of the reflective part can be reduced.

[0038] Furthermore, in order to protect the multilayer reflective film 2, the thickness of the cover layer 3 is preferably 1.0 nm or more, and more preferably 1.5 nm or more, in the state of the residual film after the absorption part 4 is formed.

[0039] Furthermore, in order to suppress the film thickness of the absorption portion 4, the film thickness of the cover layer 3 before patterning, i.e., the film thickness of the cover layer 3 in the photomask blank, is preferably 4.5 nm or less, more preferably 3.5 nm or less. In addition, in order to reduce the damage caused by patterning to the multilayer reflective film 2, it is even more preferable that the residual film of the cover layer 3 is 1.5 nm or more.

[0040] (Absorption section) To reduce the projection effect, the absorber 4 according to this embodiment is preferably formed of a material with high EUV absorptivity, and more preferably of an element or compound containing at least one material with k=0.040 or higher. As the material forming the absorber 4, it is preferably composed of one or more elements or compounds selected from Te, Sb, Pt, I, Bi, Ir, Os, W, Re, Sn, In, Pd, Fe, Au, Hg, Ta, Ga, and Ni, and may also contain non-metallic materials such as oxygen, nitrogen, and hydrogen.

[0041] Furthermore, the material forming the absorber 4 preferably contains 50% or more of the aforementioned metal element in terms of atomic percentage. If the absorber 4 contains 50% or more of the aforementioned metal element in terms of atomic percentage, the extinction coefficient k of the absorber 4 for EUV can be easily set to 0.04 or more.

[0042] It should be noted that the extinction coefficient k of the absorption section 4 can be adjusted by appropriately adjusting the content ratio of the material forming the absorption section 4.

[0043] The film thickness of the absorber 4 can be in the range of 10 nm or more and 50 nm or less, more preferably in the range of 20 nm or more and 40 nm or less, and even more preferably in the range of 25 nm or more and 35 nm or less. If the film thickness of the absorber 4 is within the above-mentioned range, EUV light can be effectively absorbed, and the absorber 4 can be thinned.

[0044] Furthermore, in order to improve the pattern resolution of the absorption portion 4, one or more hard masks (not shown) may be provided on the absorption portion 4. The material of the hard mask is preferably a material containing at least one of the elements such as Cr, Si, and Ta.

[0045] (Protective layer) The protective layer 5 is a layer formed of a material resistant to hydrogen free radicals, and is a film formed on the surface and sides of the absorbent portion 4, on the capping layer 3. Furthermore, the protective layer 5 is a layer formed of the same material as the capping layer 3.

[0046] In the case of the reflective mask 10 according to this embodiment, since the protective layer 5 is the outermost layer of the reflective mask 10, it is preferable that the protective layer 5 does not obstruct the optical paths of the incident light and the reflected light. In order to prevent resolution degradation caused by projection effect, the extinction coefficient k of the outermost protective layer 5 is preferably 0.035 or less. Furthermore, in order to ensure uniform film formation on the exposed surfaces of the cover layer 3 and the exposed surfaces of the absorption portion 4 (surface and side surfaces) and resistance to hydrogen radicals, the film thickness of the protective layer 5 is preferably 2.0 nm or more, and more preferably 2.5 nm or more.

[0047] Therefore, the total film thickness of the capping layer 3 and the protective layer 5 is preferably 3.0 nm or more.

[0048] Furthermore, if the total film thickness of the capping layer 3 and the protective layer 5 increases, the decrease in EUV light reflectivity of the reflective portion and the influence of the projection effect of the absorbing portion 4 become greater. Therefore, the total film thickness of the capping layer 3 and the protective layer 5 is preferably 10 nm or less, more preferably 8 nm or less. It should be noted that... Figure 4 The figure shows the result that the EUV light reflectivity at the reflective part decreases as the total film thickness of the cover layer 3 and the protective layer 5 increases.

[0049] Furthermore, in order to maintain a contrast that allows for pattern transfer, the OD value of the absorption portion 4 and the protective layer 5 as a whole is preferably set to 1 or higher.

[0050] Thus, as the material forming the protective layer 5, a compound material with hydrogen radical resistance and an extinction coefficient k of 0.035 or less is preferred. Therefore, as... Figure 2 As shown, the protective layer 5 is preferably a layer formed from at least one of ruthenium (Ru), yttrium (Y), niobium (Nb), titanium (Ti), zirconium (Zr), molybdenum (Mo), vanadium (V), tungsten (W), silicon oxide (SiO2), yttrium oxide (Y2O3), niobium oxide (Nb2O5), titanium oxide (TiO2), zirconium oxide (ZrO2), molybdenum oxide (MoO3), vanadium oxide (V2O5), silicon oxide (SiO), and tungsten oxide (WO3), and more preferably a layer formed from 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).

[0051] Furthermore, the protective layer 5 preferably contains 50% or more of the aforementioned elements in terms of atomic percentage. If the protective layer 5 contains 50% or more of the aforementioned elements in terms of atomic percentage, the extinction coefficient k of the protective layer 5 for EUV can be easily set to 0.035 or less.

[0052] It should be noted that the extinction coefficient k of the protective layer 5 can be adjusted by appropriately adjusting the content ratio of the materials forming the protective layer 5.

[0053] It should be noted that, although in Figure 1 Although not shown in the figure, in the reflective mask 10 according to this embodiment, a back conductive film can be formed on the side of the substrate 1 opposite to the side where the multilayer reflective film 2 is formed. The back conductive film is a film used to fix the reflective mask 10 using the principle of an electrostatic chuck when it is placed in the exposure machine.

[0054] (Methods for forming the protective layer) When manufacturing the reflective mask 10 according to this embodiment, the protective layer 5 can 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).

[0055] Atomic layer deposition (ALD) can form thin films on an atomic layer basis. Therefore, the protective layer 5 formed by this method has high film thickness uniformity and high shape followability.

[0056] Furthermore, the reflective portion, where the covering layer 3 and the protective layer 5 are stacked, has a reflectivity of 50% or more for EUV light. Excellent transfer properties can be obtained if the reflectivity of this reflective portion for EUV light is 50% or more.

[0057] As mentioned above, to prevent deterioration of transferability caused by the protective layer 5, the permissible film thickness of the protective layer 5, formed in a manner covering the exposed surfaces of the capping layer 3 and the absorber 4, is limited, requiring the formed protective layer 5 to have a uniform film thickness. Therefore, by forming the protective layer 5 using an atomic layer deposition method with excellent film thickness uniformity and shape following, a reflective mask 10 with high hydrogen radical resistance can be manufactured without deterioration of pattern transferability. Here, "uniform film thickness" means that, relative to the average thickness of the protective layer 5 formed on the capping layer 3, the surface of the absorber 4, and the side surface, the thinnest portion is within -2 nm, and the thickest portion is within +2 nm. That is, in this embodiment, the film thickness of the protective layer 5 formed on the surface of the absorber 4 is within ±2 nm relative to its average thickness. Furthermore, the film thickness of the protective layer 5 formed on the side surface of the absorber 4 is within ±2 nm relative to its average thickness. Moreover, the film thickness of the protective layer 5 formed on the capping layer 3 is within ±2 nm relative to its average thickness.

[0058] Thus, in the reflective mask 10 according to this embodiment, a protective layer 5 with high hydrogen radical resistance is formed on the capping layer 3, the surface of the absorption portion 4, and its sides by atomic layer deposition. Furthermore, the capping layer 3 is also formed of a material with high hydrogen radical resistance. Therefore, the reflective mask 10 can withstand long-term use.

[0059] Furthermore, since the capping layer 3 and the protective layer 5 are uniformly formed from materials with high EUV transmittance, the deterioration of transferability caused by the formation of the capping layer 3 and the protective layer 5 can be suppressed. Therefore, even when using an absorbent layer material with low hydrogen radical resistance, high pattern transfer accuracy can be achieved.

[0060] Furthermore, since the protective layer 5 is formed of the same material as the cover layer 3, it is possible to reduce the deterioration of the transfer properties caused by the phase difference of the area on the cover layer 3 where the absorption portion 4 is not formed, i.e., the reflective portion.

[0061] Furthermore, since the protective layer 5 is formed of the same material as the cover layer 3, the adhesion between the cover layer 3 and the protective layer 5 (interlayer adhesion) can be improved.

[0062] [Example 1] Hereinafter, a reflective mask according to an embodiment of the present invention will be described using figures and tables.

[0063] like Figure 5 As shown, a multilayer reflective film 12 is formed on a synthetic quartz substrate 11 with low thermal expansion by stacking 40 layers of silicon (Si) and molybdenum (Mo) as a pair. The thickness of the multilayer reflective film 12 is 280 nm.

[0064] Next, a ruthenium (Ru) capping layer 13 is formed on the multilayer reflective film 12 as an intermediate film with a thickness of 2.5 nm. Thus, a reflective layer (reflective portion) 16 having the multilayer reflective film 12 and the capping layer 13 is formed on the substrate 11.

[0065] An absorber 14 made of platinum (Pt) is formed on the capping layer 13 with a film thickness of 26 nm. It should be noted that the extinction coefficient k of the material of the absorber 14, namely platinum (Pt), is 0.04 or higher, which is higher than the extinction coefficient k of tantalum (Ta).

[0066] Next, on the side of the substrate 11 where the multilayer reflective film 12 is not formed, a back conductive film 15 made of chromium nitride (CrN) is formed with a thickness of 100 nm.

[0067] A multi-element sputtering apparatus was used to form the various films on the substrate 11. The thickness of each film was controlled by the sputtering time.

[0068] Next, a positive chemical amplification resist (SEBP9012: manufactured by Shin-Etsu Chemical Co., Ltd.) is spin-coated onto the absorber 14 to form a film with a thickness of 120 nm, and then baked at 110 degrees for 10 minutes to form a resist film 17.

[0069] Next, the predetermined pattern is drawn on the positive chemical amplification resist using an electron beam patterning machine (JBX3030: manufactured by Nippon Electron Co., Ltd.).

[0070] Then, a baking process is performed at 110 degrees Celsius for 10 minutes, followed by spray development (SFG3000: manufactured by SIGMAMELTEC). Thus, as... Figure 6 As shown, a resist pattern 17a is formed.

[0071] Next, the resist pattern is used as an etching mask, and the absorption part 14 is patterned by dry etching with chlorine gas as the main component, forming the absorption part pattern 14a.

[0072] Next, the remaining resist pattern 17a is stripped. Thus, as... Figure 7 As shown, the absorption pattern 14a is exposed on the surface and side of the absorption portion 14.

[0073] In this embodiment, the absorption pattern 14a is an LS (line and space) pattern with a linewidth of 64nm.

[0074] It should be noted that the thickness of the capping layer 13, which is 2.5 nm thick, is reduced by 1.5 nm through the above-described patterning process, and the thickness of the patterned capping layer 13 is 1 nm. The film thickness was measured using a scanning probe microscope.

[0075] Next, a protective layer 18 made of ruthenium (Ru) was formed on the exposed surface and sides of the absorber 14 and on the reflective layer 16 (capping layer 13) using atomic layer deposition with a ruthenium (Ru) gas. The thickness of the protective layer 18 was adjusted such that the total thickness of the capping layer 13 and the protective layer 18 was 3 nm, i.e., the thickness of the protective layer 18 was 2 nm. The formed protective layer 18 has a refractive index n of 0.886 and an extinction coefficient k of 0.017.

[0076] In this way, it was made like Figure 8 The reflective photomask (hereinafter also simply referred to as "reflective mask") 100 according to Embodiment 1 is shown.

[0077] Next, for the absorption section 14 of Example 1, the reflectance Rm of the multilayer reflective film region and the reflectance Ra of the absorption film region were measured using an EUV-based reflectance measuring device. The results are shown in Table 1, indicating that the EUV reflectance in the multilayer reflective film region was manufactured to be 64.7%.

[0078] [Example 2] Forming using the same method as in Example 1 Figure 7 The absorption section pattern 14a is shown.

[0079] Next, a protective layer 18 made of ruthenium (Ru) was formed on the exposed surface and sides of the absorber 14 and on the reflective layer 16 (capping layer 13) using atomic layer deposition of a ruthenium (Ru) gas. The thickness of the protective layer 18 was adjusted such that the total thickness of the capping layer 13 and the protective layer 18 was 10 nm. The formed protective layer 18 has a refractive index n of 0.886 and an extinction coefficient k of 0.017.

[0080] In this way, it was made like Figure 8 The reflective photomask (hereinafter also simply referred to as "reflective mask") 100 according to Embodiment 2 is shown.

[0081] Next, for the absorption section 14 of Example 2, the reflectance Rm of the multilayer reflective film region and the reflectance Ra of the absorption film region were measured using an EUV-based reflectance measuring device. The results are shown in Table 1, indicating that the EUV reflectance in the multilayer reflective film region was made to be 50.6%.

[0082] [Example 3] Forming using the same method as in Example 1 Figure 7 The absorption section pattern 14a is shown.

[0083] Next, a protective layer 18 made of ruthenium (Ru) was formed on the exposed surface and sides of the absorber 14 and on the reflective layer 16 (capping layer 13) using atomic layer deposition of a ruthenium (Ru) gas. The thickness of the protective layer 18 was adjusted to achieve a total thickness of 12 nm for both the capping layer 13 and the protective layer 18. The formed protective layer 18 has a refractive index n of 0.886 and an extinction coefficient k of 0.017.

[0084] In this way, it was made like Figure 8 The reflective photomask (hereinafter also simply referred to as "reflective mask") 100 according to Embodiment 3 is shown.

[0085] Next, for the absorption section 14 of Example 3, the reflectance Rm of the multilayer reflective film region and the reflectance Ra of the absorption film region were measured using an EUV-based reflectance measuring device. The results are shown in Table 1, indicating that the EUV reflectance in the multilayer reflective film region was made to be 50.0%.

[0086] [Example 4] Except for using yttrium (Y) to form the capping layer 13, it is formed by the same method as in Example 1. Figure 7 The absorption section pattern 14a is shown.

[0087] Next, a protective layer 18 made of yttrium (Y) was formed on the exposed surface and sides of the absorber 14 and on the reflective layer 16 (capping layer 13) using atomic layer deposition with a gas containing yttrium (Y). The thickness of the protective layer 18 was adjusted such that the total thickness of the capping layer 13 and the protective layer 18 was 4 nm. The formed protective layer 18 has a refractive index n of 0.974 and an extinction coefficient k of 0.003.

[0088] In this way, it was made like Figure 8 The reflective photomask (hereinafter also simply referred to as "reflective mask") 100 according to Embodiment 4 is shown.

[0089] Next, for the absorption section 14 of Example 4, the reflectance Rm of the multilayer reflective film region and the reflectance Ra of the absorption film region were measured using an EUV-based reflectance measuring device. The results are shown in Table 1, indicating that the EUV reflectance in the multilayer reflective film region was made to be 63.0%.

[0090] [Example 5] Except for using yttrium (Y) to form the capping layer 13, it is formed by the same method as in Example 1. Figure 7 The absorption section pattern 14a is shown.

[0091] Next, a protective layer 18 made of yttrium (Y) was formed on the exposed surface and sides of the absorber 14 and on the reflective layer 16 (capping layer 13) using atomic layer deposition with a gas containing yttrium (Y). The thickness of the protective layer 18 was adjusted such that the total thickness of the capping layer 13 and the protective layer 18 was 10 nm. The formed protective layer 18 has a refractive index n of 0.974 and an extinction coefficient k of 0.003.

[0092] In this way, it was made like Figure 8 The reflective photomask (hereinafter also simply referred to as "reflective mask") 100 according to Embodiment 5 is shown.

[0093] Next, for the absorption section 14 of Example 5, the reflectance Rm of the multilayer reflective film region and the reflectance Ra of the absorption film region were measured using an EUV-based reflectance measuring device. The results are shown in Table 1, indicating that the EUV reflectance in the multilayer reflective film region was made to be 60.9%.

[0094] [Example 6] Except for using yttrium (Y) to form the capping layer 13, it is formed by the same method as in Example 1. Figure 7 The absorption section pattern 14a is shown.

[0095] Next, a protective layer 18 made of yttrium (Y) was formed on the exposed surface and sides of the absorber 14 and on the reflective layer 16 (capping layer 13) using atomic layer deposition with a gas containing yttrium (Y). The thickness of the protective layer 18 was adjusted such that the total thickness of the capping layer 13 and the protective layer 18 was 13 nm. The formed protective layer 18 has a refractive index n of 0.974 and an extinction coefficient k of 0.003.

[0096] In this way, it was made like Figure 8 The reflective photomask (hereinafter also simply referred to as "reflective mask") 100 according to Embodiment 6 is shown.

[0097] Next, for the absorption section 14 of Example 6, the reflectance Rm of the multilayer reflective film region and the reflectance Ra of the absorption film region were measured using an EUV-based reflectance measuring device. The results are shown in Table 1, indicating that the EUV reflectance in the multilayer reflective film region was made to be 58.5%.

[0098] [Example 7] Except for using niobium (Nb) to form the capping layer 13, it is formed by the same method as in Example 1. Figure 7 The absorption section pattern 14a is shown.

[0099] Next, a protective layer 18 made of niobium (Nb) was formed on the exposed surface and sides of the absorber 14 and on the reflective layer 16 (capping layer 13) using atomic layer deposition with a niobium (Nb) gas. The thickness of the protective layer 18 was adjusted such that the total thickness of the capping layer 13 and the protective layer 18 was 4 nm. The formed protective layer 18 has a refractive index n of 0.934 and an extinction coefficient k of 0.005.

[0100] In this way, it was made like Figure 8 The reflective photomask (hereinafter also simply referred to as "reflective mask") 100 according to Embodiment 7 is shown.

[0101] Next, for the absorption section 14 of Example 7, the reflectance Rm of the multilayer reflective film region and the reflectance Ra of the absorption film region were measured using an EUV-based reflectance measuring device. The results are shown in Table 1, indicating that the EUV reflectance in the multilayer reflective film region was manufactured to be 64.5%.

[0102] [Example 8] Except for using niobium (Nb) to form the capping layer 13, it is formed by the same method as in Example 1. Figure 7 The absorption section pattern 14a is shown.

[0103] Next, a protective layer 18 made of niobium (Nb) was formed on the exposed surface and sides of the absorber 14 and on the reflective layer 16 (capping layer 13) using atomic layer deposition with a niobium (Nb) gas. The thickness of the protective layer 18 was adjusted to achieve a total thickness of 12 nm for both the capping layer 13 and the protective layer 18. The formed protective layer 18 has a refractive index n of 0.934 and an extinction coefficient k of 0.005.

[0104] In this way, it was made like Figure 8 The reflective photomask (hereinafter also simply referred to as "reflective mask") 100 according to Embodiment 8 is shown.

[0105] Next, for the absorption section 14 of Example 8, the reflectance Rm of the multilayer reflective film region and the reflectance Ra of the absorption film region were measured using an EUV-based reflectance measuring device. The results are shown in Table 1, indicating that the EUV reflectance in the multilayer reflective film region was made to be 59.5%.

[0106] [Example 9] Except for the use of niobium oxide (Nb2O5) to form the capping layer 13, it is formed by the same method as in Example 1. Figure 7 The absorption section pattern 14a is shown.

[0107] Next, a protective layer 18 made of niobium oxide (Nb₂O₅) was formed on the exposed surface and sides of the absorber 14 and on the reflective layer 16 (capping layer 13) using atomic layer deposition (ALD) with a gas containing niobium (Nb) and oxygen (O). The thickness of the protective layer 18 was adjusted to a total thickness of 3 nm for both the capping layer 13 and the protective layer 18. The formed protective layer 18 has a refractive index n of 0.954 and an extinction coefficient k of 0.010.

[0108] In this way, it was made like Figure 8 The reflective photomask (hereinafter also simply referred to as "reflective mask") 100 according to Embodiment 9 is shown.

[0109] Next, for the absorption section 14 of Example 9, the reflectance Rm of the multilayer reflective film region and the reflectance Ra of the absorption film region were measured using an EUV-based reflectance measuring device. The results are shown in Table 1, indicating that the EUV reflectance in the multilayer reflective film region was manufactured to be 64.7%.

[0110] [Example 10] Except for the use of niobium oxide (Nb2O5) to form the capping layer 13, it is formed by the same method as in Example 1. Figure 7 The absorption section pattern 14a is shown.

[0111] Next, a protective layer 18 made of niobium oxide (Nb₂O₅) was formed on the exposed surface and sides of the absorber 14 and on the reflective layer 16 (capping layer 13) using atomic layer deposition (ALD) with a gas containing niobium (Nb) and oxygen (O). The thickness of the protective layer 18 was adjusted to a total thickness of 12 nm for both the capping layer 13 and the protective layer 18. The formed protective layer 18 has a refractive index n of 0.954 and an extinction coefficient k of 0.010.

[0112] In this way, it was made like Figure 8 The reflective photomask (hereinafter also simply referred to as "reflective mask") 100 according to Embodiment 10 is shown.

[0113] Next, for the absorption section 14 of Example 10, the reflectivity Rm of the multilayer reflective film region (reflective section) and the reflectivity Ra of the absorption film region (absorption section) were measured using an EUV-based reflectivity measuring device. The results are shown in Table 1, and it can be seen that the EUV light reflectivity of the area on the cover layer 13 where the absorption section 14 is not formed, i.e., the reflective section, was made to be 51.7%.

[0114] [Example 11] Except for using vanadium (V) to form the capping layer 13, it is formed by the same method as in Example 1. Figure 7 The absorption section pattern 14a is shown.

[0115] Next, a protective layer 18 made of vanadium (V) is formed on the exposed surface and sides of the absorber 14 and on the reflective layer 16 (capping layer 13) using atomic layer deposition with a vanadium (V) gas. The thickness of the protective layer 18 is adjusted such that the total thickness of the capping layer 13 and the protective layer 18 is 4 nm. The formed protective layer 18 has a refractive index n of 0.943 and an extinction coefficient k of 0.025.

[0116] In this way, it was made like Figure 8 The reflective photomask (hereinafter also simply referred to as "reflective mask") 100 according to Embodiment 11 is shown.

[0117] Next, for the absorption section 14 of Example 11, the reflectance Rm of the multilayer reflective film region and the reflectance Ra of the absorption film region were measured using an EUV-based reflectance measuring device. The results are shown in Table 1, indicating that the EUV reflectance of the reflective section was manufactured to be 56.7%.

[0118] [Example 12] Except for using chromium (Cr) to form the coating layer 13, it is formed by the same method as in Example 1. Figure 7 The absorption section pattern 14a is shown.

[0119] Next, a protective layer 18 made of chromium (Cr) is formed on the exposed surface and sides of the absorber 14 and on the reflective layer 16 (capping layer 13) using atomic layer deposition with a chromium (Cr) gas. The thickness of the protective layer 18 is adjusted such that the total thickness of the capping layer 13 and the protective layer 18 is 3 nm. The formed protective layer 18 has a refractive index n of 0.933 and an extinction coefficient k of 0.039.

[0120] In this way, it was made like Figure 8 The reflective photomask (hereinafter also simply referred to as "reflective mask") 100 according to Embodiment 12 is shown.

[0121] Next, for the absorption section 14 of Example 12, the reflectance Rm of the multilayer reflective film region and the reflectance Ra of the absorption film region were measured using an EUV-based reflectance measuring device. The results are shown in Table 1, indicating that the EUV reflectance of the reflective section was manufactured to be 59.0%.

[0122] [Example 13] Except for the use of chromium oxide (Cr2O3) to form the capping layer 13, it is formed by the same method as in Example 1. Figure 7 The absorption section pattern 14a is shown.

[0123] Next, a protective layer 18 made of chromium oxide (Cr2O3) was formed on the exposed surface and sides of the absorber 14 and on the reflective layer 16 (capping layer 13) using atomic layer deposition (ALD) with a gas containing chromium (Cr) and oxygen (O). The thickness of the protective layer 18 was adjusted to a total thickness of 4 nm for both the capping layer 13 and the protective layer 18. The formed protective layer 18 has a refractive index n of 0.928 and an extinction coefficient k of 0.036.

[0124] In this way, it was made like Figure 8 The reflective photomask (hereinafter also simply referred to as "reflective mask") 100 according to Embodiment 13 is shown.

[0125] Next, for the absorption section 14 of Example 13, the reflectivity Rm of the multilayer reflective film region and the reflectivity Ra of the absorption film region were measured using an EUV-based reflectivity measuring device. The results are shown in Table 1, indicating that the EUV reflectivity of the reflective section was manufactured to be 54.2%.

[0126] [Example 14] Except for the use of silicon oxide (SiO2) to form the capping layer 13, it is formed by the same method as in Example 1. Figure 7 The absorption section pattern 14a is shown.

[0127] Next, a protective layer 18 made of silicon oxide (SiO2) is formed on the exposed surface and side surfaces of the absorber 14 and on the reflective layer 16 (capping layer 13) using atomic layer deposition (ALD) with a gas containing silicon (Si) and oxygen (O). The thickness of the protective layer 18 is adjusted such that the total thickness of the capping layer 13 and the protective layer 18 is 3 nm. The formed protective layer 18 has a refractive index n of 0.974 and an extinction coefficient k of 0.013.

[0128] In this way, it was made like Figure 8 The reflective photomask (hereinafter also simply referred to as "reflective mask") 100 shown according to Embodiment 14.

[0129] Next, for the absorption section 14 of Example 14, the reflectivity Rm of the multilayer reflective film region and the reflectivity Ra of the absorption film region were measured using an EUV-based reflectivity measuring device. The results are shown in Table 1, indicating that the EUV reflectivity of the reflective section was manufactured to be 61.5%.

[0130] [Example 15] Except for the use of silicon oxide (SiO2) to form the capping layer 13, it is formed by the same method as in Example 1. Figure 7 The absorption section pattern 14a is shown.

[0131] Next, a protective layer 18 made of silicon oxide (SiO2) is formed on the exposed surface and side surfaces of the absorber 14 and on the reflective layer 16 (capping layer 13) using atomic layer deposition (ALD) with a gas containing silicon (Si) and oxygen (O). The thickness of the protective layer 18 is adjusted such that the total thickness of the capping layer 13 and the protective layer 18 is 10 nm. The formed protective layer 18 has a refractive index n of 0.974 and an extinction coefficient k of 0.013.

[0132] In this way, it was made like Figure 8 The reflective photomask (hereinafter also simply referred to as "reflective mask") 100 according to Embodiment 15 is shown.

[0133] Next, for the absorption section 14 of Example 15, the reflectance Rm of the multilayer reflective film region and the reflectance Ra of the absorption film region were measured using an EUV-based reflectance measuring device. The results are shown in Table 1, indicating that the EUV reflectance of the reflective section was manufactured to be 52.0%.

[0134] [Comparative Example 1] Forming using the same method as in Example 1 Figure 7 The absorption section pattern 14a is shown.

[0135] Next, a protective layer 18 made of ruthenium (Ru) was formed on the exposed surface and sides of the absorber 14 and on the reflective layer 16 (capping layer 13) using atomic layer deposition with a gas containing ruthenium (Ru). The thickness of the protective layer 18 was adjusted such that the total thickness of the capping layer 13 and the protective layer 18 was 2 nm. The formed protective layer 18 has a refractive index n of 0.886 and an extinction coefficient k of 0.017.

[0136] In this way, it was made like Figure 8 The reflective photomask 100 shown is based on Comparative Example 1 (hereinafter also simply referred to as "reflective mask").

[0137] Next, for the absorption section 14 of Comparative Example 1, the reflectance Rm of the multilayer reflective film region and the reflectance Ra of the absorption film region were measured using an EUV-based reflectance measuring device. The results are shown in Table 1, indicating that the EUV reflectance of the reflective section was manufactured to be 64.2%.

[0138] [Comparative Example 2] Except for the use of niobium oxide (Nb2O5) to form the capping layer 13, it is formed by the same method as in Example 1. Figure 7 The absorption section pattern 14a is shown.

[0139] Next, a protective layer 18 made of niobium oxide (Nb₂O₅) was formed on the exposed surface and sides of the absorber 14 and on the reflective layer 16 (capping layer 13) using atomic layer deposition (ALD) with a gas containing niobium (Nb) and oxygen (O). The thickness of the protective layer 18 was adjusted such that the total thickness of the capping layer 13 and the protective layer 18 was 2 nm. The formed protective layer 18 has a refractive index n of 0.954 and an extinction coefficient k of 0.010.

[0140] In this way, it was made like Figure 8 The reflective photomask (hereinafter also simply referred to as "reflective mask") 100 according to Comparative Example 2 is shown.

[0141] Next, for the absorption section 14 of Comparative Example 2, the reflectance Rm of the multilayer reflective film region and the reflectance Ra of the absorption film region were measured using an EUV-based reflectance measuring device. The results are shown in Table 1, indicating that the EUV reflectance of the reflective section was manufactured to be 63.2%.

[0142] [Comparative Example 3] Except for using vanadium (V) to form the capping layer 13, it is formed by the same method as in Example 1. Figure 7 The absorption section pattern 14a is shown.

[0143] Next, a protective layer 18 made of vanadium (V) is formed on the exposed surface and sides of the absorber 14 and on the reflective layer 16 (capping layer 13) using atomic layer deposition with a vanadium (V) gas. The thickness of the protective layer 18 is adjusted such that the total thickness of the capping layer 13 and the protective layer 18 is 11 nm. The formed protective layer 18 has a refractive index n of 0.943 and an extinction coefficient k of 0.025.

[0144] In this way, it was made like Figure 8 The reflective photomask (hereinafter also simply referred to as "reflective mask") 100 according to Comparative Example 3 is shown.

[0145] Next, for the absorption section 14 of Comparative Example 3, the reflectance Rm of the multilayer reflective film region and the reflectance Ra of the absorption film region were measured using an EUV-based reflectance measuring device. The results are shown in Table 1, indicating that the EUV reflectance of the reflective section was manufactured to be 42.0%.

[0146] [Comparative Example 4] Except for the use of chromium oxide (Cr2O3) to form the capping layer 13, it is formed by the same method as in Example 1. Figure 7 The absorption section pattern 14a is shown.

[0147] Next, a protective layer 18 made of chromium oxide (Cr2O3) was formed on the exposed surface and sides of the absorber 14 and on the reflective layer 16 (capping layer 13) using atomic layer deposition (ALD) with a gas containing chromium (Cr) and oxygen (O). The thickness of the protective layer 18 was adjusted to a total thickness of 7 nm for both the capping layer 13 and the protective layer 18. The formed protective layer 18 has a refractive index n of 0.928 and an extinction coefficient k of 0.036.

[0148] In this way, it was made like Figure 8 The reflective photomask (hereinafter also simply referred to as "reflective mask") 100 shown is based on Comparative Example 4.

[0149] Next, for the absorption section 14 of Comparative Example 4, the reflectance Rm of the multilayer reflective film region and the reflectance Ra of the absorption film region were measured using an EUV-based reflectance measuring device. The results are shown in Table 1, indicating that the EUV reflectance of the reflective section was manufactured to be 37.3%.

[0150] [Comparative Example 5] Except for using chromium (Cr) to form the coating layer 13, it is formed by the same method as in Example 1. Figure 7 The absorption section pattern 14a is shown.

[0151] Next, a protective layer 18 made of chromium (Cr) is formed on the exposed surface and sides of the absorber 14 and on the reflective layer 16 (capping layer 13) using atomic layer deposition with a chromium (Cr) gas. The thickness of the protective layer 18 is adjusted such that the total thickness of the capping layer 13 and the protective layer 18 is 7 nm. The formed protective layer 18 has a refractive index n of 0.933 and an extinction coefficient k of 0.039.

[0152] In this way, it was made like Figure 8 The reflective photomask (hereinafter also simply referred to as "reflective mask") 100 shown is based on Comparative Example 5.

[0153] Next, for the absorber section 14 of Comparative Example 5, the reflectance Rm of the multilayer reflective film region and the reflectance Ra of the absorber section were measured using an EUV-based reflectance measuring device. The results are shown in Table 1, indicating that the EUV reflectance of the reflective section was manufactured to be 35.8%.

[0154] In the embodiments and comparative examples described above, the thicknesses of the cover layer 13 and the protective layer 18 were measured by transmission electron microscopy.

[0155] [EUV reflectance] In this embodiment, if the EUV reflectance is above 50%, it has sufficient transferability and is therefore qualified.

[0156] [Hydrogen radical resistance] Hydrogen was excited using a 2.45 GHz Microwave Plasma (MWP) flux of 100 sscm, and a reflective photomask was fabricated on one of the electrodes at an inter-electrode distance of 18 mm. The thickness variation of the absorption film after hydrogen radical treatment was confirmed using atomic force microscopy (AFM) and evaluated using a scale of ◎, 〇, and ×. It should be noted that measurements were performed using an LS pattern with a linewidth of 200 nm.

[0157] In addition, in this embodiment, "◎" and "〇" are qualified.

[0158] <Evaluation Criteria> ◎: Regarding the case where no change in film thickness was observed due to hydrogen free radicals. 〇: Regarding the observation of minute film thickness changes related to hydrogen free radicals. ×: Regarding the observed film thickness changes related to hydrogen free radicals. The evaluation results are shown in Table 1.

[0159] [Table 1]

[0160] [Seamless fit (interlayer tightness)] In this embodiment, the cover layer 13 and the protective layer 18 are formed of the same material. Therefore, the cover layer 13 and the protective layer 18 have a degree of adhesion that can be regarded as a single layer (monolayer).

[0161] Therefore, the adhesion (interlayer adhesion) between the cover layer 13 and the protective layer 18 in this embodiment is not a problem in use, and is therefore qualified.

[0162] As shown in Table 1, based on the evaluation results of Examples 1 to 15 and Comparative Examples 1 to 5, if the extinction coefficient k of the absorber 14 for EUV is 0.04 or more, the cover layer 13 and the protective layer 18 are formed of the same material, the reflectivity of EUV light in the area of ​​the cover layer 13 where the absorber 14 is not formed, i.e., the reflective part (multilayer reflective film area), is 50% or more, and the total film thickness of the cover layer 13 and the protective layer 18 is 3 nm or more, and the cover layer 13 and the protective layer 18 are resistant to hydrogen radicals, then a reflective photomask with excellent hydrogen radical resistance, capable of reducing the deterioration of transferability caused by the phase difference of the reflective part, and capable of improving the adhesion (interlayer adhesion) between the cover layer 13 and the protective layer 18 can be provided.

[0163] Furthermore, for example, the present invention may be configured as follows. (1) A reflective photomask, which has the following characteristics: substrate; A reflective layer, which is formed on the substrate and comprises a multilayer film that reflects EUV light; A cover layer is formed on the reflective layer; An absorption portion, which is formed on a portion of the covering layer and absorbs EUV light; and A protective layer is formed on the cover layer, the absorbent portion, and the side surface of the absorbent portion. The extinction coefficient k of the absorber for EUV light is 0.04 or higher. The covering layer and the protective layer are formed of the same material. The area on the cover layer where the absorption portion is not formed, i.e., the reflective portion, has a reflectivity of more than 50% for EUV light. The total thickness of the capping layer and the protective layer is 3 nm or more. The capping layer and the protective layer are resistant to hydrogen radicals. (2) According to the reflective photomask described in (1) above, the extinction coefficient k of the cover layer and the protective layer for EUV light is 0.035 or less. (3) According to the reflective photomask described in (1) or (2) above, the total film thickness of the cover layer and the protective layer is less than 10 nm. (4) According to any one of (1) to (3) above, the reflective photomask, wherein the cover layer and the protective layer are formed of a metal or metal oxide film comprising at least one of ruthenium (Ru), silicon (Si), yttrium (Y), niobium (Nb), titanium (Ti), zirconium (Zr), molybdenum (Mo), vanadium (V) and tungsten (W).

[0168] Industrial applicability The reflective mask according to the present invention can be used in the manufacturing process of semiconductor integrated circuits and the like to form fine patterns by EUV exposure.

Claims

1. A reflective photomask, comprising: substrate; A reflective layer, which is formed on the substrate and comprises a multilayer film that reflects EUV light; A cover layer is formed on the reflective layer; An absorption portion, which is formed on a portion of the covering layer and absorbs EUV light; and A protective layer is formed on the cover layer, the absorbent portion, and the side surface of the absorbent portion. The extinction coefficient k of the absorber for EUV light is 0.04 or higher. The covering layer and the protective layer are formed of the same material. The area on the cover layer where the absorption portion is not formed, i.e., the reflective portion, has a reflectivity of more than 50% for EUV light. The total thickness of the capping layer and the protective layer is 3 nm or more. The capping layer and the protective layer are resistant to hydrogen radicals.

2. The reflective photomask according to claim 1, wherein, The extinction coefficient k of the capping layer and the protective layer for EUV light is less than 0.

035.

3. The reflective photomask according to claim 1, wherein, The total thickness of the cover layer and the protective layer is less than 10 nm.

4. The reflective photomask according to any one of claims 1 to 3, wherein, The capping layer and the protective layer are respectively 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).

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