Reflective photomask blanks and reflective photomasks

Abstract

The purpose of the present disclosure is to provide a reflective photomask blank and a reflective photomask that maximize the effectiveness of a phase shift effect and that possess high transferability (especially resolution). A reflective photomask blank (100) according to one embodiment of the present disclosure is characterized by: comprising a substrate (11), a reflective layer (12) for reflecting EUV light and having a multilayer film structure formed atop the substrate (11), a protective layer (13) that is formed atop the reflective layer (12) and that protects the reflective layer (12), and an absorption layer (14) for absorbing EUV light and formed atop the protective layer (13); and the absorption layer (14) having a phase difference within a range from 200 degrees to 280 degrees.

Description

[Technical Field]

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

[0002] In the manufacturing process of semiconductor devices, the miniaturization of semiconductor devices has led to increasing demands for miniaturization of photolithography technology. The minimum development dimension of the transferred 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 in the manufacturing process of cutting-edge semiconductor devices is being replaced from the conventional 193 nm wavelength ArF excimer laser light to 13.5 nm wavelength EUV (Extreme Ultraviolet).

[0003] Because most materials have high optical absorption properties for EUV, conventional refractive optical systems that utilize light transmission cannot be used. Therefore, mirrors are used as optical components in exposure machines instead of lenses. Photomasks also change from conventional transmissive to reflective EUV photomasks. Because the incident and reflected light on the EUV photomask cannot be designed to be coaxial, EUV lithography typically employs a technique in which the optical axis is tilted 6° from the perpendicular direction of the EUV photomask, allowing the EUV light to enter the mask and the reflected light reflected at a minus 6° angle is irradiated onto the semiconductor substrate. However, tilting the optical axis causes the EUV light incident on the EUV photomask to cast a shadow on the EUV photomask pattern (the absorber layer pattern), resulting in poor transfer performance. Improving transfer performance will be a key challenge for further miniaturization in the future.

[0004] Current EUV photomasks use a tantalum (Ta)-based film with a thickness of 60 to 90 nm as the light absorption layer. When this EUV photomask is used for pattern transfer exposure, depending on the relationship between the incident direction and the orientation of the mask pattern, there is a risk of a decrease in contrast at the shadowed edge of the mask pattern. This can lead to problems such as increased line edge roughness of the transferred pattern on the semiconductor substrate and inability to form line widths to the targeted dimensions, resulting in a deterioration in transfer performance.

[0005] To address this issue, methods have been proposed that use a material with a high extinction coefficient k in the absorption layer to reduce EUV reflectance (see, for example, Patent Document 1), and that use the phase shift effect (see, for example, Patent Document 2).

[0006] In a reflective phase-shift mask, the reflected light that passes through the absorption layer and is attenuated has a phase difference with the light reflected by the aperture. Similar to a transmissive phase-shift mask, this reflective phase-shift mask can improve the contrast of the optical image on the wafer and the resolution of the transferred pattern by utilizing the phase shift effect.

[0007] For example, a reflective mask using the phase shift effect described in Patent Document 2 has an optimum phase difference of 170 to 190 degrees, which includes the optimum phase difference of 180 degrees for conventional transmissive phase shift masks.

[0008] However, in the case of a reflective mask, EUV light is incident at an angle, so part of the reflected light passes through the edge of the absorber layer pattern. The reflected light that hits the edge is out of phase with the light reflected from the center of the pattern, so the optimal phase difference for the absorber layer is different from 180 degrees. In other words, the inventors discovered that the optimal phase difference for the absorber layer in a reflective mask is a value different from the "180 degrees" used in conventional design concepts. As described above, the reflective phase shift mask according to the prior art has not been able to fully utilize the phase shift effect, and its transferability (particularly resolution) has been insufficient. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] International Publication No. 2018 / 159785 [Patent Document 2] Patent No. 6287099 Summary of the Invention [Problem to be solved by the invention]

[0010] An object of the present disclosure is to provide a reflective photomask blank and a reflective photomask that make maximum use of the phase shift effect and have high transferability (particularly resolution). [Means for solving the problem]

[0011] The present invention has been made to solve the above-mentioned problems, and provides a reflective photomask blank according to one embodiment of the present invention, comprising: a substrate; a reflective layer having a multilayer film structure formed on the substrate and reflecting EUV light; a protective layer formed on the reflective layer and protecting the reflective layer; and an absorbing layer formed on the protective layer and absorbing EUV light, wherein the absorbing layer has a phase difference in the range of 200 degrees or more and 280 degrees or less.

[0012] Furthermore, the absorbing layer in the reflective photomask blank according to one aspect of the present invention may have a phase difference in the range of 215 degrees or more and 270 degrees or less.

[0013] Furthermore, the absorbing layer in the reflective photomask blank according to one aspect of the present invention may have a phase difference in the range of 230 degrees or more and 260 degrees or less.

[0014] Furthermore, in the reflective photomask blank according to one aspect of the present invention, the absorbing layer may have a refractive index n for EUV light that is smaller than 0.93.

[0015] Furthermore, in the reflective photomask blank according to one aspect of the present invention, the absorbing layer may have a refractive index n for EUV light that is smaller than 0.92.

[0016] Furthermore, the absorption layer in the reflective photomask blank according to one embodiment of the present invention may be made of a material containing at least one element selected from the group consisting of Ru, Rh, Mo, Pd, Ag, Pt, Au, Os, Ir, and Re.

[0017] Furthermore, the absorber layer in the reflective photomask blank according to one aspect of the present invention may have a reflectance to EUV light in the range of 2% or more and 20% or less.

[0018] Furthermore, in the reflective photomask blank according to one aspect of the present invention, the absorption layer may be made of a material containing at least one element selected from the group consisting of Pt, Au, Ir, and Re.

[0019] Furthermore, the absorption layer in the reflective photomask blank according to one embodiment of the present invention may be made of a material containing at least one element selected from the group consisting of Mo, W, Nb, Hg, Fe, Ta, V, Bi, Ti, Zr, Hf, C, B, Be, and Al.

[0020] A reflective photomask according to one embodiment of the present invention comprises a substrate, a reflective layer having a multilayer structure formed on the substrate and reflecting EUV light, a protective layer formed on the reflective layer and protecting the reflective layer, and an absorbing pattern layer formed on the protective layer and absorbing EUV light in which a pattern is formed, wherein the absorbing pattern layer has a phase difference in the range of 200 degrees or more and 280 degrees or less.

[0021] Furthermore, in the reflective photomask according to one aspect of the present invention, the absorbing pattern layer may have a phase difference in the range of 215 degrees or more and 270 degrees or less.

[0022] Furthermore, in the reflective photomask according to one aspect of the present invention, the absorbing pattern layer may have a phase difference in the range of 230 degrees or more and 260 degrees or less.

[0023] Furthermore, in the reflective photomask according to one aspect of the present invention, the absorbing pattern layer may have a refractive index n for EUV light that is smaller than 0.93.

[0024] Furthermore, in the reflective photomask according to one aspect of the present invention, the absorbing pattern layer may have a refractive index n for EUV light that is smaller than 0.92.

[0025] Furthermore, the absorption pattern layer in the reflective photomask according to one embodiment of the present invention may be made of a material containing at least one element selected from the group consisting of Ru, Rh, Mo, Pd, Ag, Pt, Au, Os, Ir, and Re.

[0026] Furthermore, in the reflective photomask according to one aspect of the present invention, the absorbing pattern layer may have a reflectance to EUV light in the range of 2% to 20%.

[0027] In addition, in the reflective photomask according to one aspect of the present invention, the absorbing pattern layer may be made of a material containing at least one element selected from the group consisting of Pt, Au, Ir, and Re.

[0028] Furthermore, the absorption pattern layer in the reflective photomask according to one embodiment of the present invention may be made of a material containing at least one element selected from the group consisting of Mo, W, Nb, Hg, Fe, Ta, V, Bi, Ti, Zr, Hf, C, B, Be, and Al. [Effects of the Invention]

[0029] With the reflective photomask blank and reflective photomask according to one embodiment of the present disclosure, a sufficient phase shift effect can be obtained, making it possible to improve wafer transfer performance (particularly resolution). [Brief explanation of the drawings]

[0030] [Figure 1] FIG. 1 is a cross-sectional view showing the structure of a reflective photomask blank according to an embodiment of the present invention. [Figure 2] 1 is a cross-sectional view showing the structure of a reflective photomask according to an embodiment of the present invention. [Figure 3] 1 is a graph showing the optical constants of various metal materials at the wavelength of EUV light. [Figure 4] 1 is a schematic cross-sectional view showing the structure of a reflective photomask blank according to an embodiment of the present invention. [Figure 5] 1A to 1C are schematic cross-sectional views illustrating a manufacturing process of a reflective photomask according to an embodiment of the present invention. [Figure 6] 1A to 1C are schematic cross-sectional views illustrating a manufacturing process of a reflective photomask according to an embodiment of the present invention. [Figure 7] 1A to 1C are schematic cross-sectional views illustrating a manufacturing process of a reflective photomask according to an embodiment of the present invention. [Figure 8] 1 is a schematic cross-sectional view showing the structure of a reflective photomask according to an embodiment of the present invention. [Figure 9] 1 is a graph showing the NILS of a reflective photomask according to an example of the present invention. [Figure 10] 1 is a graph showing a phase difference of a reflective photomask according to an example of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0031] An embodiment of the present disclosure will be described with reference to the drawings. The configurations shown in the drawings are schematic, and the relationship between thickness and planar dimensions, the thickness ratio of each layer, etc., differ from the actual ones. Furthermore, the embodiments shown below are examples of configurations for embodying the technical idea of ​​the present disclosure, and the technical idea of ​​the present disclosure is not limited to the materials, shapes, structures, etc. of the components described below. The technical idea of ​​the present disclosure can be modified in various ways within the technical scope defined by the claims.

[0032] (Configuration of reflective photomask blank and reflective photomask) FIG. 1 is a schematic cross-sectional view showing a reflective photomask blank 100 according to an embodiment of the present invention. As shown in FIG. 1, the reflective photomask blank 100 according to an embodiment of the present invention includes a substrate 11, a reflective layer 12 formed on the substrate 11, a protective layer 13 formed on the reflective layer 12, and an absorbing layer 14 formed on the protective layer 13. FIG. 2 is a schematic cross-sectional view showing a reflective photomask 200 according to an embodiment of the present invention. Here, the reflective photomask 200 according to an embodiment of the present invention shown in FIG. 2 is formed by patterning the absorbing layer 14 of the reflective photomask blank 100 according to an embodiment of the present invention shown in FIG. Each layer will be described in detail below.

[0033] (substrate) The substrate 11 according to the embodiment of the present invention may be, for example, a flat Si substrate, a synthetic quartz substrate, etc. Furthermore, low thermal expansion glass containing titanium may be used for the substrate 11, but the present embodiment is not limited to these as long as the material has a small thermal expansion coefficient. 4, which will be described later, a back surface conductive film 15 can be formed on the surface of the substrate 11 on which the reflective layer 12 is not formed. The back surface conductive film 15 is a film for fixing the reflective photomask 200 by utilizing the principle of an electrostatic chuck when the reflective photomask 200 is placed in an exposure machine.

[0034] (reflective layer) The reflective layer 12 according to the embodiment of the present invention may be any layer that reflects EUV light (extreme ultraviolet light), which is exposure light, and may be a multilayer reflective film made of a combination of materials with significantly different refractive indices for EUV light (i.e., an EUV light reflective film having a multilayer structure). The reflective layer 12 including a multilayer reflective film may be formed by repeatedly stacking layers of a combination of, for example, Mo (molybdenum) and Si (silicon) or Mo (molybdenum) and Be (beryllium) for about 40 periods.

[0035] (protective layer) The protective layer 13 according to the embodiment of the present invention functions as an etching stopper that prevents damage to the reflective layer 12 when the absorbing pattern layer 14a is formed by etching. Note that the protective layer 13 may not be necessary depending on the material of the reflective layer 12 and the etching conditions. The protective layer 13 is formed of a material that is resistant to dry etching that is performed when forming the pattern of the absorbing layer 14. For example, the material of the protective layer 13 may be ruthenium (Ru).

[0036] (Absorbent layer and absorbent pattern layer) As shown in Fig. 1, the absorbing layer 14 is a layer formed on the protective layer 13, and is a layer that absorbs EUV light, which is exposure light. The absorbing layer 14 also forms an absorbing pattern layer (transfer pattern) 14a, which is a fine pattern for transfer. That is, by removing a portion of the absorbing layer 14 of the reflective photomask blank 100, i.e., by patterning the absorbing layer 14, the absorbing pattern (absorbing pattern layer 14a) of the reflective photomask 200 shown in Fig. 2 is formed.

[0037] In the areas where the absorbing layer 14 (absorbent pattern layer 14a) is formed, EUV light is absorbed and a portion of the light is reflected. On the other hand, in the openings of the pattern (areas where the absorbing layer 14 is not present), the EUV light is reflected from the reflective layer 12 via the protective layer 13. The light reflected from the areas where the absorbing layer 14 is formed forms a desired phase difference with the light reflected from the openings.

[0038] In general, the reflectance of the absorbing layer 14 and the phase difference with respect to the opening resulting from patterning are uniquely determined once the optical constants (refractive index n, extinction coefficient k) and film thickness of each layer of the reflective photomask blank and the reflective photomask, and the wavelength of light to be used are determined, and can be calculated based on optical theory (for details, see, for example, Applied Physics and Engineering Selection 3, "Thin Film" by Yoshida Sadafumi, Baifukan, 1990). In other words, the "phase difference" in this embodiment means the difference between the phase of reflected light from the absorbing layer 14 and the phase of reflected light from the reflective layer 12 (at the opening). In the present embodiment, the values of the refractive index n and the extinction coefficient k used for calculating the reflectance and the phase difference were measured values using EUV light.

[0039] The NILS (Normalized Image Logarithmic Slope) of the wafer pattern when transferring the wafer using the reflective photomask 200 depends on the phase difference of the reflective photomask 200. FIG. 9 shows the NILS (Normalized Image Logarithmic Slope) when exposing a 19 nm hole pattern on the wafer under exposure conditions with a numerical aperture NA of 0.33, where the absorption layer 14 (absorption pattern layer 14a) is a single-layer film using a mixed material of rhodium (Rh) and aluminum (Al). The graph was obtained at four levels of film thicknesses of 38 nm, 41 nm, 47 nm, and 54 nm. Since Rh has a refractive index n = 0.875 and an extinction coefficient k = 0.03, and Al has a refractive index n = 1.03 and an extinction coefficient k = 0.03, when changing the composition of RhAl, the refractive index changes within the range of 0.875 < n < 1.03, and the extinction coefficient is approximately constant at k = 0.03. Also, when comparing at the same film thickness, when changing the composition of RhAl, that is, when changing the refractive index n, the phase difference changes. In FIG. 9, the phase difference is taken on the horizontal axis to show the relationship with NILS.

[0040] NILS (Normalized Image Logarithmic Slope) is NILS = w × dln(I) / dx ··· Equation (1) It is a value of contrast obtained by this formula and is an index of the resolution of the wafer pattern when forming the wafer pattern using the reflective photomask 200. Here, "w" represents the line width, and "I" represents the intensity of the energy latent image. Note that the larger the value of NILS, the higher the resolution of the transferred pattern.

[0041] As shown in FIG. 9, there is a relationship between the phase difference and NILS, and NILS becomes maximum when the phase difference is in the vicinity of 230 degrees to 260 degrees. Also, as shown in FIG. 9, when the film thickness is 54 nm and the phase difference of the absorption pattern layer 14a formed of RhAl is 180 degrees, the value of NILS is 2.49. In contrast, the NILS value when the phase difference is 200 degrees is 2.60, and the NILS value when the phase difference is 280 degrees is 2.60, both of which are approximately 5% higher than when the phase difference is 180 degrees. Furthermore, the NILS value when the phase difference is 215 degrees is 2.68, and when the phase difference is 270 degrees is 2.67, both of which are approximately 7% higher than when the phase difference is 180 degrees. Furthermore, the NILS value when the phase difference is 230 degrees is 2.72, and when the phase difference is 260 degrees is 2.71, both of which are approximately 9% higher than when the phase difference is 180 degrees. Furthermore, when the phase difference is 240 degrees, the NILS is maximized at 2.74, which is approximately 10% higher than when the phase difference is 180 degrees.

[0042] In this way, compared to when the phase difference is 180 degrees, the NILS improves by 5% or more when the phase difference is between 200 degrees and 280 degrees, by 7% or more when the phase difference is between 215 degrees and 270 degrees, and by 9% or more when the phase difference is between 230 degrees and 260 degrees.

[0043] Furthermore, as shown in FIG. 9, when the thickness of the absorption pattern layer 14a is 47 nm and the phase difference is 240 degrees, the NILS value is 2.76, which is about 12% higher than when the phase difference is 180 degrees. Furthermore, as shown in FIG. 9, when the thickness of the absorption pattern layer 14a is 41 nm and the phase difference is 240 degrees, the NILS value is 2.78, which is about 13% higher than when the phase difference is 180 degrees. Furthermore, as shown in FIG. 9, when the film thickness of the absorption pattern layer 14a is 38 nm and the phase difference is 240 degrees, the NILS value is 2.71, which is approximately 31% higher than when the phase difference is 180 degrees.

[0044] From these facts, it can be seen that in order to improve resolution, the phase difference of the absorption layer 14 is preferably in the range of 200 degrees or more and 280 degrees or less, more preferably in the range of 215 degrees or more and 270 degrees or less, and most preferably in the range of 230 degrees or more and 260 degrees or less.

[0045] In EUV lithography, EUV light is incident at an angle and reflected by the reflective layer 12, but the absorbing layer 14 (absorbent pattern layer 14a) obstructs the light path, causing a projection effect that can degrade the transfer performance onto the wafer (semiconductor substrate). It is known that this deterioration in transfer performance can be reduced by reducing the thickness of the absorbing layer 14 that absorbs EUV light.

[0046] The thickness of the absorber layer 14 is preferably 60 nm or less. When the thickness of the absorber layer 14 is 60 nm or less, the projection effect can be sufficiently reduced compared to conventional Ta-based absorber films, and transfer performance can be improved.

[0047] FIG. 10 is a graph showing the relationship between the film thickness of the absorbing layer 14 and the phase difference calculated by simulation when the refractive index n of the absorbing layer 14 for EUV light is 0.90, 0.91, 0.92, 0.93, and 0.94. As shown in FIG. 10, the smaller the refractive index n of the absorption layer 14 for EUV light, the thinner the film thickness can be to obtain a desired phase difference. When the refractive index n of the absorption layer 14 for EUV light is 0.93, the minimum film thickness required to obtain a phase difference of 230 to 260 degrees is 60 nm, which is similar to the film thickness of a conventional Ta-based absorption film. Therefore, if the refractive index n of the absorption layer 14 for EUV light is less than 0.93, the film thickness can be made thinner than 60 nm, which is preferable. Furthermore, if the refractive index n of the absorption layer 14 for EUV light is less than 0.92, the minimum film thickness required to obtain a phase difference of 230 to 260 degrees is 50 nm or less, which is even more preferable.

[0048] Figure 3 is a graph showing the optical constants of each metal material for EUV light at a wavelength of 13.5 nm. The horizontal axis of the graph in Figure 3 represents the refractive index n, and the vertical axis represents the extinction coefficient k. Figure 3 shows that the refractive index n of each of Ru, Rh, Mo, Pd, Ag, Pt, Au, Os, Ir, and Re is less than 0.93, so the use of this material group can reduce the projection effect. For convenience, the above-mentioned "Ru, Rh, Mo, Pd, Ag, Pt, Au, Os, Ir, and Re" will be defined as the "first material group" below.

[0049] The material of the absorption layer 14 may be a mixture as long as it contains elements from the first material group. If it is a mixture, the optical constants (refractive index n, extinction coefficient k) of the absorption layer 14 can be controlled by changing the composition, and the desired phase difference and reflectance can be obtained. In other words, it is preferable that the absorption layer 14 be made of a material containing at least one element selected from the group consisting of Ru, Rh, Mo, Pd, Ag, Pt, Au, Os, Ir, and Re.

[0050] In addition to the first material group described above, the material of the absorption layer 14 may further include at least one of tin (Sn), indium (In), tantalum (Ta), aluminum (Al), niobium (Nb), and titanium (Ti). Oxides, nitrides, or oxynitrides of Sn, In, and Ta have high melting points, which can be expected to further improve heat resistance and improve processability in existing etching equipment. Furthermore, Al, Nb, and Ti can be expected to further improve cleaning resistance by forming a passivation film. Here, if the above-mentioned "Sn, In, Ta, Al, Nb, and Ti" are defined as a "second material group" for convenience, the absorption layer 14 may be composed only of elements of the first material group, or may be composed of elements of the first material group and elements of the second material group. Furthermore, the absorption layer 14 may be composed of elements of the first material group and elements other than the elements of the second material group, or may be composed of elements of the first material group, elements of the second material group, and elements other than the elements of the second material group. When the absorption layer 14 is composed of elements of the first material group and elements of the second material group, the content of the elements of the first material group is preferably 70 atomic % or more, more preferably 80 atomic % or more, and even more preferably 90 atomic % or more of the elements in the entire absorption layer 14.

[0051] The material of the absorption layer 14 is preferably composed of a material containing at least one element selected from Pt, Au, Ir, and Re. Among the first material group described above, Pt, Au, Ir, and Re are materials that are expected to improve processability in existing etching equipment and are also highly resistant to hydrogen radicals used in cleaning EUV exposure equipment. Furthermore, because their refractive index n is smaller than 0.92, they are expected to reduce the projection effect. For convenience, the aforementioned "Pt, Au, Ir, and Re" are hereinafter defined as the "third material group."

[0052] The material of the absorber layer 14 may further include at least one of Mo, W, Nb, Hg, Fe, Ta, V, Bi, Ti, Zr, Hf, C, B, Be, and Al in addition to the third material group described above. Here, "Mo, W, Nb, Hg, Fe, Ta, V, Bi, Ti, Zr, Hf, C, B, Be, and Al" are defined as a "fourth material group." If the fourth material group is included, improved processability in existing etching equipment and improved resistance to hydrogen radicals can be expected.

[0053] The absorption layer 14 may be composed only of elements from the third material group, or may be composed of elements from the third material group and elements from the fourth material group. Furthermore, the absorption layer 14 may be composed of elements from the third material group and elements other than elements from the fourth material group, or may be composed of elements from the third material group, elements from the fourth material group, and elements other than elements from the fourth material group. When the absorption layer 14 is composed of elements from the third material group and elements from the fourth material group, it is preferable that the content of elements from the third material group be 20 atomic % or more of the total elements in the absorption layer 14.

[0054] To obtain a sufficient phase shift effect, the reflectance of the absorbing layer 14 is preferably 1% to 30% in absolute reflectance, more preferably 2% to 20%. Here, "absolute reflectance" refers to a value calculated as the ratio of the amount of light reflected by an actual sample to the amount of light directly measured from a light source. In other words, it refers to the reflectance when the intensity of incident light is taken as 100%. The term "absolute reflectance" is used in this embodiment to distinguish it from "relative reflectance," which refers to the ratio of the reflectance (approximately 66%) of the multilayer reflective layer (reflective layer 12) to the reflectance of the absorbing layer 14. Thus, the "absolute reflectance" in this embodiment is a different concept from "relative reflectance."

[0055] A hard mask layer may be provided on the absorption layer 14. The hard mask layer is made of a material that is resistant to dry etching, such as a Cr-based film or a Si-based film.

[0056] [Example] The present disclosure will be explained in more detail below using examples, but the present disclosure is not limited to these examples in any way.

[0057] Example 1 A synthetic quartz substrate with low thermal expansion was used as the substrate shown in Figure 4. On the substrate, 40 layers of a laminated film consisting of a pair of silicon (Si) and molybdenum (Mo) were stacked to form a multilayer reflective film. The film thickness of the multilayer reflective film was 280 nm. Next, a capping layer (protective layer) was formed on the multilayer reflective film using ruthenium (Ru) to a thickness of 3.5 nm, thereby forming a reflective portion on the substrate, which had the multilayer reflective film and the capping layer. An absorber layer containing rhodium (Rh) and aluminum (Al) was formed on the capping layer to a thickness of 47 nm. The atomic ratio of rhodium (Rh) to aluminum (Al) in the absorber layer was measured using XPS (X-ray photoelectron spectroscopy) and found to be 66:34. Furthermore, the crystallinity of the absorber layer was measured using XRD (X-ray diffraction) and found to be amorphous, although slight crystallinity was observed. Next, a back surface conductive film was formed of chromium nitride (CrN) to a thickness of 100 nm on the side of the substrate on which the multilayer reflective film was not formed, thereby producing a reflective photomask blank 100.

[0058] A multi-target sputtering system was used to deposit each film on the substrate, and the thickness of each film was controlled by the sputtering time.

[0059] Next, a method for producing a reflective photomask 200 will be described with reference to Fig. 5 to Fig. 8. As shown in Fig. 5, a positive chemically amplified resist (SEBP9012, manufactured by Shin-Etsu Chemical Co., Ltd.) was applied to a film thickness of 120 nm on the absorption layer 14 of the reflective photomask blank 100 by spin coating, and baked at 110°C for 10 minutes to form a resist film 16. Next, a predetermined pattern was written on the resist film 16 using an electron beam writing machine (JBX3030, manufactured by JEOL Ltd.). Thereafter, a pre-baking treatment was carried out at 110° C. for 10 minutes, and then a development treatment was carried out using a spray developer (SFG3000: manufactured by Sigma Meltec Co., Ltd.), thereby forming a resist pattern 16a as shown in FIG.

[0060] Next, using the resist pattern 16a as an etching mask, the absorbing layer 14 was patterned by dry etching mainly using a chlorine-based gas, thereby forming an absorbing pattern (absorbing pattern layer) 14a in the absorbing layer 14, as shown in FIG. Next, the resist pattern 16a was removed to produce a reflective photomask 200 according to this example, as shown in FIG. In this example, the absorbing pattern 14a formed in the absorbing layer 14 was a 76 nm hole pattern on a reflective photomask 200 for transfer evaluation.

[0061] The refractive index and extinction coefficient of the absorbing layer formed as described above were measured (actually measured) using EUV light with a wavelength of 13.5 nm. As a result, the refractive index n and extinction coefficient k of the absorbing layer of Example 1 were found to be n=0.924 and k=0.03, respectively. In the same manner as in Example 1, the refractive index and extinction coefficient of the absorbing layer were measured (actually measured) for each of the following Examples and Comparative Examples using EUV light with a wavelength of 13.5 nm.

[0062] The absorption layer had an absolute reflectance of 3.4% at a wavelength of 13.5 nm and a phase difference of 205 degrees.

[0063] <Example 2> The composition of the RhAl material of the absorption layer was changed to an atomic ratio of Rh:Al=70:30, and the film was formed to a thickness of 47 nm. A reflective photomask of Example 2 was produced in the same manner as in Example 1.

[0064] The refractive index n and extinction coefficient k of the absorption layer of Example 2 formed as described above at a wavelength of 13.5 nm were n=0.919 and k=0.03, respectively.

[0065] The absorption layer had an absolute reflectance of 3.7% at a wavelength of 13.5 nm and a phase difference of 220 degrees.

[0066] Example 3 The composition of the RhAl material of the absorption layer was changed to an atomic ratio of Rh:Al=75:25, and the film was formed to a thickness of 47 nm. A reflective photomask of Example 3 was produced in the same manner as in Example 1.

[0067] The refractive index n and extinction coefficient k of the absorption layer of Example 3 formed as described above at a wavelength of 13.5 nm were n=0.912 and k=0.03, respectively.

[0068] The absorption layer had an absolute reflectance of 4.3% at a wavelength of 13.5 nm and a phase difference of 240 degrees.

[0069] Example 4 The composition of the RhAl material of the absorption layer was changed so that the atomic ratio was Rh:Al=82:18, and the film was formed to a thickness of 47 nm. A reflective photomask of Example 4 was produced in the same manner as in Example 1.

[0070] The refractive index n and extinction coefficient k of the absorption layer of Example 4 formed as described above at a wavelength of 13.5 nm were n=0.902 and k=0.03, respectively.

[0071] The absorption layer had an absolute reflectance of 5.3% at a wavelength of 13.5 nm and a phase difference of 265 degrees.

[0072] <Example 5> The composition of the RhAl material of the absorption layer was changed so that the atomic ratio was Rh:Al=86:14, and the film was formed to a thickness of 47 nm. A reflective photomask of Example 5 was produced in the same manner as in Example 1.

[0073] The refractive index n and extinction coefficient k of the absorption layer of Example 5 formed as described above at a wavelength of 13.5 nm were n=0.896 and k=0.03, respectively.

[0074] The absorption layer had an absolute reflectance of 5.9% at a wavelength of 13.5 nm and a phase difference of 275 degrees.

[0075] Example 6 The composition of the RhAl material of the absorption layer was changed so that the atomic ratio was Rh:Al=67:33, and the film was formed to a thickness of 54 nm. A reflective photomask of Example 6 was produced in the same manner as in Example 1.

[0076] The refractive index n and extinction coefficient k of the absorption layer of Example 6 formed as described above at a wavelength of 13.5 nm were n=0.923 and k=0.03, respectively.

[0077] The absorption layer had an absolute reflectance of 2.6% at a wavelength of 13.5 nm and a phase difference of 240 degrees.

[0078] Example 7 The composition of the RhAl material of the absorption layer was changed so that the atomic ratio was Rh:Al=84:16, and the film was formed to a thickness of 41 nm. A reflective photomask of Example 7 was produced in the same manner as in Example 1.

[0079] The refractive index n and extinction coefficient k of the absorption layer of Example 7 formed as described above at a wavelength of 13.5 nm were n=0.899 and k=0.03, respectively.

[0080] The absorption layer had an absolute reflectance of 4.4% at a wavelength of 13.5 nm and a phase difference of 240 degrees.

[0081] Example 8 The composition of the RhAl material of the absorption layer was changed so that the atomic ratio was Rh:Al=98:2, and the film was formed to a thickness of 38 nm. A reflective photomask of Example 8 was produced in the same manner as in Example 1.

[0082] The refractive index n and extinction coefficient k of the absorption layer of Example 8 formed as described above at a wavelength of 13.5 nm were n=0.878 and k=0.03, respectively.

[0083] The absorption layer had an absolute reflectance of 9.2% at a wavelength of 13.5 nm and a phase difference of 240 degrees.

[0084] Example 9 A reflective photomask of Example 9 was produced in the same manner as in Example 1, except that the material of the absorbing layer was changed to rhodium (Rh) and the film was formed to a thickness of 33 nm.

[0085] The refractive index n and extinction coefficient k of the absorption layer of Example 9 formed as described above at a wavelength of 13.5 nm were n=0.875 and k=0.03, respectively.

[0086] The absorption layer had an absolute reflectance of 11.0% at a wavelength of 13.5 nm and a phase difference of 240 degrees.

[0087] Example 10 The material of the absorption layer was changed to a homogeneous mixed material (RuNb) of ruthenium (Ru) and niobium (Nb) with an atomic ratio of 85:15, and the film was formed to a thickness of 44 nm. A reflective photomask of Example 10 was fabricated in the same manner as in Example 1.

[0088] The refractive index n and extinction coefficient k of the absorption layer of Example 10 formed as described above at a wavelength of 13.5 nm were n=0.895 and k=0.015, respectively.

[0089] The absorption layer had an absolute reflectance of 17.0% at a wavelength of 13.5 nm and a phase difference of 240 degrees.

[0090] Example 11 The material of the absorption layer was changed to a homogeneous mixed material (RuAl) of ruthenium (Ru) and aluminum (Al) with an atomic ratio of 59:41, and the film was formed to a thickness of 72 nm. A reflective photomask of Example 11 was fabricated in the same manner as in Example 1.

[0091] The refractive index n and extinction coefficient k of the absorption layer of Example 11 formed as described above at a wavelength of 13.5 nm were n=0.940 and k=0.023, respectively.

[0092] The absorption layer had an absolute reflectance of 3.7% at a wavelength of 13.5 nm and a phase difference of 240 degrees.

[0093] Example 12 The material of the absorption layer was changed to a homogeneous mixed material (SnRuO) of tin oxide (SnO) and ruthenium (Ru) with an atomic ratio of 20:80, and the film was formed to a thickness of 42 nm. A reflective photomask of Example 12 was fabricated in the same manner as in Example 1.

[0094] The refractive index n and extinction coefficient k of the absorption layer of Example 12 formed as described above at a wavelength of 13.5 nm were n=0.896 and k=0.03, respectively.

[0095] The absorption layer had an absolute reflectance of 3.1% at a wavelength of 13.5 nm and a phase difference of 240 degrees.

[0096] Example 13 A reflective photomask of Example 13 was produced in the same manner as in Example 12, except that the thickness of the SnRuO absorbing layer was changed to 39 nm.

[0097] The refractive index n and extinction coefficient k of the absorption layer of Example 13 formed as described above at a wavelength of 13.5 nm were n=0.896 and k=0.03, respectively.

[0098] The absorption layer had an absolute reflectance of 8.9% at a wavelength of 13.5 nm and a phase difference of 225 degrees.

[0099] Example 14 The material of the absorption layer was changed to a homogeneous mixed material (InRuO) of indium oxide (InO) and ruthenium (Ru) with an atomic ratio of 15:85, and the film was formed to a thickness of 42 nm. A reflective photomask of Example 14 was fabricated in the same manner as in Example 1.

[0100] The refractive index n and extinction coefficient k of the absorption layer of Example 14 formed as described above at a wavelength of 13.5 nm were n=0.895 and k=0.03, respectively.

[0101] The absorption layer had an absolute reflectance of 3.3% at a wavelength of 13.5 nm and a phase difference of 240 degrees.

[0102] Example 15 A reflective photomask of Example 15 was produced in the same manner as in Example 14, except that the thickness of the InRuO absorbing layer was changed to 39 nm.

[0103] The refractive index n and extinction coefficient k of the absorption layer of Example 15 formed as described above at a wavelength of 13.5 nm were n=0.895 and k=0.03, respectively.

[0104] The absorption layer had an absolute reflectance of 9.3% at a wavelength of 13.5 nm and a phase difference of 225 degrees.

[0105] Example 16 The material of the absorption layer was changed to a homogeneous mixed material (TaTi) of tantalum (Ta) and titanium (Ti) with an atomic ratio of 60:40, and the film was formed to a thickness of 78 nm. A reflective photomask of Example 16 was fabricated in the same manner as in Example 1.

[0106] The refractive index n and extinction coefficient k of the absorption layer of Example 16 formed as described above at a wavelength of 13.5 nm were n=0.947 and k=0.030, respectively.

[0107] The absorption layer had an absolute reflectance of 1.2% at a wavelength of 13.5 nm and a phase difference of 212 degrees.

[0108] Example 17 A reflective photomask of Example 17 was produced in the same manner as in Example 1, except that the material of the absorption layer was changed to titanium (Ti) and the film was formed to a thickness of 80 nm.

[0109] The refractive index n and extinction coefficient k of the absorption layer of Example 17 formed as described above at a wavelength of 13.5 nm were n=0.952 and k=0.014, respectively.

[0110] The absorption layer had an absolute reflectance of 6.5% at a wavelength of 13.5 nm and a phase difference of 212 degrees.

[0111] Example 18 The material of the absorption layer was changed to a homogeneous mixed material (MoPd) of molybdenum (Mo) and palladium (Pd) with an atomic ratio of 40:60, and the film was formed to a thickness of 45 nm. A reflective photomask of Example 18 was fabricated in the same manner as in Example 1.

[0112] The refractive index n and extinction coefficient k of the absorption layer of Example 18 formed as described above at a wavelength of 13.5 nm were n=0.896 and k=0.03, respectively.

[0113] The absorption layer had an absolute reflectance of 6.6% at a wavelength of 13.5 nm and a phase difference of 235 degrees.

[0114] Example 19 A reflective photomask of Example 19 was produced in the same manner as in Example 1, except that the material of the absorption layer was changed to platinum (Pt) and the film was formed to a thickness of 45 nm.

[0115] The refractive index n and extinction coefficient k of the absorption layer of Example 19 formed as described above at a wavelength of 13.5 nm were n=0.890 and k=0.06, respectively.

[0116] The absorption layer had an absolute reflectance of 1.3% at a wavelength of 13.5 nm and a phase difference of 243 degrees.

[0117] Example 20 The material of the absorption layer was changed to a homogeneous mixed material (IrPt) of iridium (Ir) and platinum (Pt) with an atomic ratio of 75:25, and the film was formed to a thickness of 45 nm. A reflective photomask of Example 20 was fabricated in the same manner as in Example 1.

[0118] The refractive index n and extinction coefficient k of the absorption layer of Example 20 formed as described above at a wavelength of 13.5 nm were n=0.902 and k=0.049, respectively.

[0119] The absorption layer had an absolute reflectance of 2.2% at a wavelength of 13.5 nm and a phase difference of 234 degrees.

[0120] <Example 21> The material of the absorption layer was changed to a homogeneous mixed material (IrAu) of iridium (Ir) and gold (Au) with an atomic ratio of 40:60, and the film was formed to a thickness of 45 nm. A reflective photomask of Example 21 was produced in the same manner as in Example 1.

[0121] The refractive index n and extinction coefficient k of the absorption layer of Example 21 formed as described above at a wavelength of 13.5 nm were n=0.901 and k=0.049, respectively.

[0122] The absorption layer had an absolute reflectance of 2.2% at a wavelength of 13.5 nm and a phase difference of 234 degrees.

[0123] <Example 22> The material of the absorption layer was changed to a homogeneous mixed material (RePt) of rhenium (Re) and platinum (Pt) with an atomic ratio of 75:25, and the film was formed to a thickness of 46 nm. A reflective photomask of Example 22 was fabricated in the same manner as in Example 1.

[0124] The refractive index n and extinction coefficient k of the absorption layer of Example 22 formed as described above at a wavelength of 13.5 nm were n=0.909 and k=0.045, respectively.

[0125] The absorption layer had an absolute reflectance of 2.2% at a wavelength of 13.5 nm and a phase difference of 240 degrees.

[0126] Example 23 The material of the absorption layer was changed to a homogeneous mixed material (ReAu) of rhenium (Re) and gold (Au) with an atomic ratio of 40:60, and the film was formed to a thickness of 45 nm. A reflective photomask of Example 23 was fabricated in the same manner as in Example 1.

[0127] The refractive index n and extinction coefficient k of the absorption layer of Example 23 formed as described above at a wavelength of 13.5 nm were n=0.905 and k=0.047, respectively.

[0128] The absorption layer had an absolute reflectance of 2.8% at a wavelength of 13.5 nm and a phase difference of 227 degrees.

[0129] Example 24 The material of the absorption layer was changed to a homogeneous mixed material (PtMo) of platinum (Pt) and molybdenum (Mo) with an atomic ratio of 20:80, and the film was formed to a thickness of 48 nm. A reflective photomask of Example 24 was fabricated in the same manner as in Example 1.

[0130] The refractive index n and extinction coefficient k of the absorption layer of Example 24 formed as described above at a wavelength of 13.5 nm were n=0.918 and k=0.017, respectively.

[0131] The absorption layer had an absolute reflectance of 7.8% at a wavelength of 13.5 nm and a phase difference of 213 degrees.

[0132] Example 25 The material of the absorption layer was changed to a homogeneous mixed material (PtMo) of platinum (Pt) and molybdenum (Mo) with an atomic ratio of 80:20, and the film was formed to a thickness of 45 nm. A reflective photomask of Example 25 was produced in the same manner as in Example 1.

[0133] The refractive index n and extinction coefficient k of the absorption layer of Example 25 formed as described above at a wavelength of 13.5 nm were n=0.898 and k=0.049, respectively.

[0134] The absorption layer had an absolute reflectance of 2.2% at a wavelength of 13.5 nm and a phase difference of 234 degrees.

[0135] Example 26 The material of the absorption layer was changed to a homogeneous mixed material (PtNb) of platinum (Pt) and niobium (Nb) with an atomic ratio of 35:65, and the film was formed to a thickness of 47 nm. A reflective photomask of Example 26 was fabricated in the same manner as in Example 1.

[0136] The refractive index n and extinction coefficient k of the absorption layer of Example 26 formed as described above at a wavelength of 13.5 nm were n=0.919 and k=0.024, respectively.

[0137] The absorption layer had an absolute reflectance of 6% at a wavelength of 13.5 nm and a phase difference of 214 degrees.

[0138] Example 27 The material of the absorption layer was changed to a homogeneous mixed material (PtNb) of platinum (Pt) and niobium (Nb) with an atomic ratio of 80:20, and the film was formed to a thickness of 45 nm. A reflective photomask of Example 27 was produced in the same manner as in Example 1.

[0139] The refractive index n and extinction coefficient k of the absorption layer of Example 27 formed as described above at a wavelength of 13.5 nm were n=0.900 and k=0.049, respectively.

[0140] The absorption layer had an absolute reflectance of 2.2% at a wavelength of 13.5 nm and a phase difference of 234 degrees.

[0141] Example 28 The material of the absorption layer was changed to a homogeneous mixed material (AuMo) of gold (Au) and molybdenum (Mo) with an atomic ratio of 25:75, and the film was formed to a thickness of 49 nm. A reflective photomask of Example 28 was fabricated in the same manner as in Example 1.

[0142] The refractive index n and extinction coefficient k of the absorption layer of Example 28 formed as described above at a wavelength of 13.5 nm were n=0.918 and k=0.018, respectively.

[0143] The absorption layer had an absolute reflectance of 7.6% at a wavelength of 13.5 nm and a phase difference of 209 degrees.

[0144] Example 29 The material of the absorption layer was changed to a homogeneous mixed material (AuMo) of gold (Au) and molybdenum (Mo) with an atomic ratio of 95:5, and the film was formed to a thickness of 39 nm. A reflective photomask of Example 29 was fabricated in the same manner as in Example 1.

[0145] The refractive index n and extinction coefficient k of the absorption layer of Example 29 formed as described above at a wavelength of 13.5 nm were n=0.900 and k=0.050, respectively.

[0146] The absorption layer had an absolute reflectance of 2.7% at a wavelength of 13.5 nm and a phase difference of 228 degrees.

[0147] Example 30 The material of the absorption layer was changed to a homogeneous mixed material (AuNb) of gold (Au) and niobium (Nb) with an atomic ratio of 45:55, and the film was formed to a thickness of 48 nm. A reflective photomask of Example 30 was fabricated in the same manner as in Example 1.

[0148] The refractive index n and extinction coefficient k of the absorption layer of Example 30 formed as described above at a wavelength of 13.5 nm were n=0.918 and k=0.026, respectively.

[0149] The absorption layer had an absolute reflectance of 4.5% at a wavelength of 13.5 nm and a phase difference of 213 degrees.

[0150] Example 31 The material of the absorption layer was changed to a homogeneous mixed material (AuNb) of gold (Au) and niobium (Nb) with an atomic ratio of 90:10, and the film was formed to a thickness of 45 nm. A reflective photomask of Example 31 was fabricated in the same manner as in Example 1.

[0151] The refractive index n and extinction coefficient k of the absorption layer of Example 31 formed as described above at a wavelength of 13.5 nm were n=0.903 and k=0.047, respectively.

[0152] The absorption layer had an absolute reflectance of 2.2% at a wavelength of 13.5 nm and a phase difference of 234 degrees.

[0153] Example 32 The material of the absorption layer was changed to a homogeneous mixed material (AuTi) of gold (Au) and titanium (Ti) with an atomic ratio of 65:35, and the film was formed to a thickness of 47 nm. A reflective photomask of Example 32 was fabricated in the same manner as in Example 1.

[0154] The refractive index n and extinction coefficient k of the absorption layer of Example 32 formed as described above at a wavelength of 13.5 nm were n=0.918 and k=0.039, respectively.

[0155] The absorption layer had an absolute reflectance of 1.3% at a wavelength of 13.5 nm and a phase difference of 225 degrees.

[0156] Example 33 The material of the absorption layer was changed to a homogeneous mixed material (AuTi) of gold (Au) and titanium (Ti) with an atomic ratio of 85:15, and the film was formed to a thickness of 46 nm. A reflective photomask of Example 33 was fabricated in the same manner as in Example 1.

[0157] The refractive index n and extinction coefficient k of the absorption layer of Example 33 formed as described above at a wavelength of 13.5 nm were n=0.907 and k=0.046, respectively.

[0158] The absorption layer had an absolute reflectance of 2.2% at a wavelength of 13.5 nm and a phase difference of 240 degrees.

[0159] Example 34 The material of the absorption layer was changed to a homogeneous mixed material (AuZr) of gold (Au) and zirconium (Zr) with an atomic ratio of 70:30, and the film was formed to a thickness of 51 nm. A reflective photomask of Example 34 was fabricated in the same manner as in Example 1.

[0160] The refractive index n and extinction coefficient k of the absorption layer of Example 34 formed as described above at a wavelength of 13.5 nm were n=0.917 and k=0.038, respectively.

[0161] The absorption layer had an absolute reflectance of 2.1% at a wavelength of 13.5 nm and a phase difference of 218 degrees.

[0162] Example 35 The material of the absorption layer was changed to a homogeneous mixed material (AuZr) of gold (Au) and zirconium (Zr) with an atomic ratio of 90:10, and the film was formed to a thickness of 46 nm. A reflective photomask of Example 35 was produced in the same manner as in Example 1.

[0163] The refractive index n and extinction coefficient k of the absorption layer of Example 35 formed as described above at a wavelength of 13.5 nm were n=0.905 and k=0.047, respectively.

[0164] The absorption layer had an absolute reflectance of 2.5% at a wavelength of 13.5 nm and a phase difference of 248 degrees.

[0165] Example 36 The material of the absorption layer was changed to a homogeneous mixed material (IrMo) of iridium (Ir) and molybdenum (Mo) with an atomic ratio of 30:70, and the film was formed to a thickness of 49 nm. A reflective photomask of Example 36 was fabricated in the same manner as in Example 1.

[0166] The refractive index n and extinction coefficient k of the absorption layer of Example 36 formed as described above at a wavelength of 13.5 nm were n=0.918 and k=0.018, respectively.

[0167] The absorption layer had an absolute reflectance of 7.6% at a wavelength of 13.5 nm and a phase difference of 209 degrees.

[0168] Example 37 The material of the absorption layer was changed to a homogeneous mixed material (IrMo) of iridium (Ir) and molybdenum (Mo) with an atomic ratio of 90:10, and the film was formed to a thickness of 45 nm. A reflective photomask of Example 37 was produced in the same manner as in Example 1.

[0169] The refractive index n and extinction coefficient k of the absorption layer of Example 37 formed as described above at a wavelength of 13.5 nm were n=0.907 and k=0.041, respectively.

[0170] The absorption layer had an absolute reflectance of 3.7% at a wavelength of 13.5 nm and a phase difference of 227 degrees.

[0171] Example 38 The material of the absorption layer was changed to a homogeneous mixed material (IrW) of iridium (Ir) and tungsten (W) with an atomic ratio of 50:50, and the film was formed to a thickness of 47 nm. A reflective photomask of Example 38 was fabricated in the same manner as in Example 1.

[0172] The refractive index n and extinction coefficient k of the absorption layer of Example 38 formed as described above at a wavelength of 13.5 nm were n=0.919 and k=0.039, respectively.

[0173] The absorption layer had an absolute reflectance of 1.3% at a wavelength of 13.5 nm and a phase difference of 225 degrees.

[0174] Example 39 The material of the absorption layer was changed to a homogeneous mixed material (IrW) of iridium (Ir) and tungsten (W) with an atomic ratio of 90:10, and the film was formed to a thickness of 46 nm. A reflective photomask of Example 39 was fabricated in the same manner as in Example 1.

[0175] The refractive index n and extinction coefficient k of the absorption layer of Example 39 formed as described above at a wavelength of 13.5 nm were n=0.908 and k=0.044, respectively.

[0176] The absorption layer had an absolute reflectance of 2.2% at a wavelength of 13.5 nm and a phase difference of 240 degrees.

[0177] <Example 40> The material of the absorption layer was changed to a homogeneous mixed material (IrNb) of iridium (Ir) and niobium (Nb) with an atomic ratio of 50:50, and the film was formed to a thickness of 47 nm. A reflective photomask of Example 40 was produced in the same manner as in Example 1.

[0178] The refractive index n and extinction coefficient k of the absorption layer of Example 40 formed as described above at a wavelength of 13.5 nm were n=0.920 and k=0.025, respectively.

[0179] The absorption layer had an absolute reflectance of 6% at a wavelength of 13.5 nm and a phase difference of 214 degrees.

[0180] <Example 41> The material of the absorption layer was changed to a homogeneous mixed material (IrNb) of iridium (Ir) and niobium (Nb) with an atomic ratio of 90:10, and the film was formed to a thickness of 46 nm. A reflective photomask of Example 41 was produced in the same manner as in Example 1.

[0181] The refractive index n and extinction coefficient k of the absorption layer of Example 41 formed as described above at a wavelength of 13.5 nm were n=0.908 and k=0.041, respectively.

[0182] The absorption layer had an absolute reflectance of 3.1% at a wavelength of 13.5 nm and a phase difference of 237 degrees.

[0183] <Example 42> The material of the absorption layer was changed to a homogeneous mixed material (IrTa) of iridium (Ir) and tantalum (Ta) with an atomic ratio of 85:15, and the film was formed to a thickness of 45 nm. A reflective photomask of Example 42 was fabricated in the same manner as in Example 1.

[0184] The refractive index n and extinction coefficient k of the absorption layer of Example 42 formed as described above at a wavelength of 13.5 nm were n=0.911 and k=0.044, respectively.

[0185] The absorption layer had an absolute reflectance of 2.8% at a wavelength of 13.5 nm and a phase difference of 219 degrees.

[0186] <Example 43> The material of the absorption layer was changed to a homogeneous mixed material (IrTa) of iridium (Ir) and tantalum (Ta) with an atomic ratio of 95:5, and the film was formed to a thickness of 46 nm. A reflective photomask of Example 43 was fabricated in the same manner as in Example 1.

[0187] The refractive index n and extinction coefficient k of the absorption layer of Example 43 formed as described above at a wavelength of 13.5 nm were n=0.907 and k=0.045, respectively.

[0188] The absorption layer had an absolute reflectance of 2.5% at a wavelength of 13.5 nm and a phase difference of 248 degrees.

[0189] <Example 44> The material of the absorption layer was changed to a homogeneous mixed material (IrV) of iridium (Ir) and vanadium (V) with an atomic ratio of 65:35, and the film was formed to a thickness of 45 nm. A reflective photomask of Example 44 was produced in the same manner as in Example 1.

[0190] The refractive index n and extinction coefficient k of the absorption layer of Example 44 formed as described above at a wavelength of 13.5 nm were n=0.918 and k=0.038, respectively.

[0191] The absorption layer had an absolute reflectance of 3.4% at a wavelength of 13.5 nm and a phase difference of 201 degrees.

[0192] Example 45 The material of the absorption layer was changed to a homogeneous mixed material (IrV) of iridium (Ir) and vanadium (V) with an atomic ratio of 90:10, and the film was formed to a thickness of 46 nm. A reflective photomask of Example 45 was produced in the same manner as in Example 1.

[0193] The refractive index n and extinction coefficient k of the absorption layer of Example 45 formed as described above at a wavelength of 13.5 nm were n=0.909 and k=0.043, respectively.

[0194] The absorption layer had an absolute reflectance of 2.2% at a wavelength of 13.5 nm and a phase difference of 240 degrees.

[0195] <Example 46> The material of the absorption layer was changed to a homogeneous mixed material (ReMo) of rhenium (Re) and molybdenum (Mo) with an atomic ratio of 45:55, and the film was formed to a thickness of 48 nm. A reflective photomask of Example 46 was fabricated in the same manner as in Example 1.

[0196] The refractive index n and extinction coefficient k of the absorption layer of Example 46 formed as described above at a wavelength of 13.5 nm were n=0.920 and k=0.021, respectively.

[0197] The absorption layer had an absolute reflectance of 7.8% at a wavelength of 13.5 nm and a phase difference of 213 degrees.

[0198] Example 47 The material of the absorption layer was changed to a homogeneous mixed material (ReMo) of rhenium (Re) and molybdenum (Mo) with an atomic ratio of 90:10, and the film was formed to a thickness of 47 nm. A reflective photomask of Example 47 was fabricated in the same manner as in Example 1.

[0199] The refractive index n and extinction coefficient k of the absorption layer of Example 47 formed as described above at a wavelength of 13.5 nm were n=0.916 and k=0.037, respectively.

[0200] The absorption layer had an absolute reflectance of 2.5% at a wavelength of 13.5 nm and a phase difference of 234 degrees.

[0201] <Example 48> The material of the absorption layer was changed to a homogeneous mixed material (ReW) of rhenium (Re) and tungsten (W) with an atomic ratio of 75:25, and the film was formed to a thickness of 46 nm. A reflective photomask of Example 48 was fabricated in the same manner as in Example 1.

[0202] The refractive index n and extinction coefficient k of the absorption layer of Example 48 formed as described above at a wavelength of 13.5 nm were n=0.920 and k=0.038, respectively.

[0203] The absorption layer had an absolute reflectance of 2.4% at a wavelength of 13.5 nm and a phase difference of 216 degrees.

[0204] <Example 49> The material of the absorption layer was changed to a homogeneous mixed material (ReW) of rhenium (Re) and tungsten (W) with an atomic ratio of 95:5, and the film was formed to a thickness of 46 nm. A reflective photomask of Example 49 was fabricated in the same manner as in Example 1.

[0205] The refractive index n and extinction coefficient k of the absorption layer of Example 49 formed as described above at a wavelength of 13.5 nm were n=0.916 and k=0.040, respectively.

[0206] The absorption layer had an absolute reflectance of 2.8% at a wavelength of 13.5 nm and a phase difference of 227 degrees.

[0207] Example 50 The material of the absorption layer was changed to a homogeneous mixed material (ReNb) of rhenium (Re) and niobium (Nb) with an atomic ratio of 75:25, and the film was formed to a thickness of 48 nm. A reflective photomask of Example 50 was fabricated in the same manner as in Example 1.

[0208] The refractive index n and extinction coefficient k of the absorption layer of Example 50 formed as described above at a wavelength of 13.5 nm were n=0.920 and k=0.031, respectively.

[0209] The absorption layer had an absolute reflectance of 2.5% at a wavelength of 13.5 nm and a phase difference of 213 degrees.

[0210] <Example 51> The material of the absorption layer was changed to a homogeneous mixed material (ReNb) of rhenium (Re) and niobium (Nb) with an atomic ratio of 90:10, and the film was formed to a thickness of 46 nm. A reflective photomask of Example 51 was produced in the same manner as in Example 1.

[0211] The refractive index n and extinction coefficient k of the absorption layer of Example 51 formed as described above at a wavelength of 13.5 nm were n=0.917 and k=0.037, respectively.

[0212] The absorption layer had an absolute reflectance of 4% at a wavelength of 13.5 nm and a phase difference of 224 degrees.

[0213] <Comparative Example 1> In Comparative Example 1, a photomask having a conventional existing film mainly made of tantalum (Ta) was used. In Comparative Example 1, an absorption layer was formed using tantalum nitride (TaN) to a thickness of 58 nm, and an outermost layer was formed using tantalum oxide (TaO) to a thickness of 2 nm to produce a reflective photomask. Otherwise, the reflective photomask of Comparative Example 1 was produced in the same manner as in Example 1.

[0214] The absorption layer of Comparative Example 1 formed as described above had an absolute reflectance of 1.3% at a wavelength of 13.5 nm and a phase difference of 160 degrees.

[0215] <Comparative Example 2> The material of the absorption layer was changed to a homogeneous mixed material (RhAl) of rhodium (Rh) and aluminum (Al) with an atomic ratio of 60:40, and the film was formed to a thickness of 47 nm. A reflective photomask of Comparative Example 2 was fabricated in the same manner as in Example 1.

[0216] The refractive index n and extinction coefficient k of the absorption layer of Comparative Example 2 formed as described above at a wavelength of 13.5 nm were n=0.932 and k=0.03, respectively.

[0217] The absorption layer had an absolute reflectance of 3.1% at a wavelength of 13.5 nm and a phase difference of 180 degrees.

[0218] <Comparative Example 3> The composition of the RhAl material of the absorption layer was changed so that the atomic ratio was Rh:Al=89:11, and the film was formed to a thickness of 47 nm. A reflective photomask of Comparative Example 3 was produced in the same manner as in Example 1.

[0219] The refractive index n and extinction coefficient k of the absorption layer of Comparative Example 3 formed as described above at a wavelength of 13.5 nm were n=0.892 and k=0.03, respectively.

[0220] The absorption layer had an absolute reflectance of 6.3% at a wavelength of 13.5 nm and a phase difference of 285 degrees.

[0221] <Evaluation> The reflective photomasks obtained in Examples 1 to 51 and Comparative Examples 1 to 3 were evaluated for transfer performance by the following method. The transfer performance was confirmed by wafer exposure evaluation. The resolution was evaluated by the NILS (Normalized Image Log-Slope) value.

[0222] Using an EUV exposure system (NXE3300B, manufactured by ASML), the absorption patterns of the reflective photomasks prepared in each example and comparative example were transferred onto a semiconductor wafer coated with an EUV positive chemically amplified resist. The exposure dose was adjusted so that the hole pattern was transferred to 19 nm as designed. The transferred resist pattern was then observed and its line width was measured using an electron beam dimension measuring device to confirm the resolution, which was then evaluated using the following four levels: "◎", "○", "△", and "×". <Evaluation criteria> ◎: NILS value is greater than 2.73 ○: NILS value is 2.48 or more and 2.73 or less △: NILS value is 2.40 or more and less than 2.48 ×: NILS value is less than 2.40 The evaluation results are shown in Table 1.

[0223] Regarding the NILS value, if the evaluation was "○" or higher, there was no problem with the transfer performance and the sample was deemed to have passed.

[0224] [Table 1]

[0225] Table 1 shows the evaluation results of Examples 1 to 51 and Comparative Examples 1 to 3. Comparative Example 1, which had a conventional tantalum (Ta)-based absorption layer with a thickness of 60 nm, had a phase difference of 160 degrees and an NILS of 2.37. When the phase difference of the absorption pattern layer was 200 degrees or more and 280 degrees or less as in Examples 1 to 51, it was found that the NILS was larger than that of Comparative Example 1 and the resolution was improved. Furthermore, compared to Comparative Example 2 in which the phase difference was 180 degrees and Comparative Example 3 in which the phase difference was 285 degrees, Examples 1 to 51 in which the phase difference was 200 degrees or more and 280 degrees or less had large NILS and improved resolution. Hereinafter, the results of comparing the NILS of each example and each comparative example will be described in detail using Table 1 and the graph shown in FIG.

[0226] 9 and Table 1, the NILS value of Comparative Example 2, in which the film thickness is 47 nm and the phase difference of the absorption pattern layer 14a formed of RhAl is 180 degrees, is 2.47. In contrast, the NILS value of Example 1, in which the phase difference is 205 degrees, is 2.66, which is about 7% higher than when the phase difference is 180 degrees (Comparative Example 2). Furthermore, the NILS value of Example 2, in which the phase difference is 220 degrees, is 2.73, which is about 10% higher than when the phase difference is 180 degrees (Comparative Example 2). Furthermore, the NILS value of Example 3, in which the phase difference is 240 degrees, is 2.76, which is about 12% higher than when the phase difference is 180 degrees (Comparative Example 2). Furthermore, the NILS value of Example 4, in which the phase difference is 265 degrees, is 2.67, which is about 8% higher than when the phase difference is 180 degrees (Comparative Example 2). Furthermore, the NILS value of Example 5, in which the phase difference is 275 degrees, is 2.56, which is about 4% higher than when the phase difference is 180 degrees (Comparative Example 2). On the other hand, the NILS value of Comparative Example 3, in which the phase difference is 285 degrees, is 2.46, which is almost the same value as when the phase difference is 180 degrees (Comparative Example 2). Furthermore, as shown in Example 6 in Figure 9 and Table 1, when the film thickness of the absorption pattern layer 14a is 54 nm, the NILS value of Example 6, in which the phase difference is 240 degrees, is 2.74, which is approximately 10% higher than when the phase difference is 180 degrees with the same film thickness. Furthermore, as shown in Example 7 in Figure 9 and Table 1, when the film thickness of the absorption pattern layer 14a is 41 nm, the NILS value of Example 7, in which the phase difference is 240 degrees, is 2.78, which is approximately 13% higher than when the phase difference is 180 degrees with the same film thickness. Furthermore, as shown in Example 8 in Figure 9 and Table 1, when the film thickness of the absorption pattern layer 14a is 38 nm, the NILS value of Example 8, in which the phase difference is 240 degrees, is 2.71, which is approximately 31% higher than when the phase difference is 180 degrees with the same film thickness.

[0227] From these findings, it can be seen that in order to improve resolution, the phase difference is preferably in the range of 200 degrees or more and 280 degrees or less, more preferably in the range of 215 degrees or more and 270 degrees or less, and most preferably in the range of 230 degrees or more and 260 degrees or less. In other words, the suitable range of phase difference for the absorbing layer in a reflective mask is "in the range of 200 degrees or more and 280 degrees or less," which is significantly different from the "range of 170 degrees or more and 190 degrees or less" used in conventional design concepts.

[0228] The NILS of Example 9, which was formed from rhodium (Rh) with a film thickness of 33 nm and had a phase difference of 240 degrees, was 2.53, and the NILS of Example 10, which was formed from a material containing ruthenium (Ru) and niobium (Nb) with a film thickness of 44 nm in an atomic ratio of 85:15 and had a phase difference of 240 degrees, was 2.48.

[0229] In Examples 6 to 10, the reflectances were 2.6%, 4.4%, 9.2%, 11.0%, and 17.0%, respectively, but regardless of the reflectance, better transferability than each comparative example was obtained in all cases. From this, it can be seen that a sufficient phase shift effect can be obtained and resolution can be improved if the reflectance is within the range of 2% to 20%.

[0230] Example 11, which was formed from a material containing ruthenium (Ru) and aluminum (Al) in an atomic ratio of 59:41 with a film thickness of 72 nm and had a phase difference of 240 degrees, had an NILS of 2.73. Since Example 11 had a high refractive index n of 0.94, the film thickness was thicker than the 60 nm conventional film of Comparative Example 1, and the projection effect could not be reduced, but the phase shift effect resulted in a good NILS.

[0231] The NILS of Example 12, which was formed from a material containing tin oxide (SnO) and ruthenium (Ru) with a film thickness of 42 nm at an atomic ratio of 20:80 and had a phase difference of 240 degrees, was 2.78. The NILS of Example 13, which was formed from a material containing tin oxide (SnO) and ruthenium (Ru) with a film thickness of 39 nm at an atomic ratio of 20:80 and had a phase difference of 225 degrees, was 2.65. The NILS of Example 14, which was formed from a material containing indium oxide (InO) and ruthenium (Ru) with a film thickness of 42 nm at an atomic ratio of 15:85 and had a phase difference of 240 degrees, was 2.78. The NILS of Example 15, which was formed from a material containing indium oxide (InO) and ruthenium (Ru) with a film thickness of 39 nm at an atomic ratio of 15:85 and had a phase difference of 225 degrees, was 2.64.

[0232] In this way, even when the absorbing layer 14 (absorbent pattern layer 14a) is formed from a material containing tin (Sn) or indium (In) which has excellent workability, a phase shift effect is obtained and resolution is improved.

[0233] Example 16, which was formed from a material containing tantalum (Ta) and titanium (Ti) in an atomic ratio of 60:40 and had a phase difference of 212 degrees, had a NILS of 2.48, while Example 17, which was formed from titanium (Ti) with a thickness of 80 nm and had a phase difference of 212 degrees, had a NILS of 2.56. Examples 16 and 17 had relatively high refractive indices n of 0.947 and 0.952, respectively, and were thicker than the 60 nm conventional film of Comparative Example 1, and were unable to reduce the projection effect. However, the phase shift effect resulted in good NILS. Furthermore, the reflectivities of Examples 16 and 17 were 1.2% and 6.5%, respectively, and Example 17, whose reflectivity was in the range of 2% to 20%, had a better NILS.

[0234] Example 18, which was formed from a material containing molybdenum (Mo) and palladium (Pd) in an atomic ratio of 40:60 and had a phase difference of 235 degrees, had an NILS of 2.76, while Example 19, which was formed from platinum (Pt) in a thickness of 45 nm and had a phase difference of 243 degrees, had an NILS of 2.72. Both Examples 18 and 19 had good NILS due to the phase shift effect. Furthermore, the reflectivities of Examples 18 and 19 were 6.6% and 1.3%, respectively, and Example 18, whose reflectivity was in the range of 2% to 20%, had a better NILS.

[0235] The NILS of Example 20, which was formed from a material containing iridium (Ir) and platinum (Pt) with a film thickness of 45 nm and an atomic ratio of 75:25, and had a phase difference of 234 degrees, was 2.74; the NILS of Example 21, which was formed from a material containing iridium (Ir) and gold (Au) with a film thickness of 45 nm and an atomic ratio of 40:60, and had a phase difference of 234 degrees, was 2.74; the NILS of Example 22, which was formed from a material containing rhenium (Re) and platinum (Pt) with a film thickness of 46 nm and an atomic ratio of 75:25, and had a phase difference of 240 degrees, was 2.75; and the NILS of Example 23, which was formed from a material containing rhenium (Re) and gold (Au) with a film thickness of 45 nm and an atomic ratio of 40:60, and had a phase difference of 227 degrees, was 2.74.

[0236] In this way, even when an absorption layer 14 (absorption pattern layer 14a) is formed that is composed only of elements from the third material group, which has a small refractive index n and excellent processability and hydrogen resistance, a phase shift effect is obtained and resolution is improved.

[0237] Example 24, which was made of a material containing platinum (Pt) and molybdenum (Mo) in an atomic ratio of 20:80 with a film thickness of 48 nm and had a phase difference of 213 degrees, had an NILS of 2.65, and Example 25, which was made of a material containing platinum (Pt) and molybdenum (Mo) in an atomic ratio of 80:20 with a film thickness of 45 nm and had a phase difference of 234 degrees, had an NILS of 2.74. In addition, Example 26, which was formed from a material containing platinum (Pt) and niobium (Nb) in an atomic ratio of 35:65 with a film thickness of 47 nm and had a phase difference of 214 degrees, had an NILS of 2.68, and Example 27, which was formed from a material containing platinum (Pt) and niobium (Nb) in an atomic ratio of 80:20 with a film thickness of 45 nm and had a phase difference of 234 degrees, had an NILS of 2.74.

[0238] In addition, Example 28, which was formed from a material containing gold (Au) and molybdenum (Mo) in an atomic ratio of 25:75 with a film thickness of 49 nm and had a phase difference of 209 degrees, had an NILS of 2.63, and Example 29, which was formed from a material containing gold (Au) and molybdenum (Mo) in an atomic ratio of 95:5 with a film thickness of 39 nm and had a phase difference of 228 degrees, had an NILS of 2.75. In addition, Example 30, which was formed from a material containing gold (Au) and niobium (Nb) in an atomic ratio of 45:55 with a film thickness of 48 nm and had a phase difference of 213 degrees, had an NILS of 2.71, and Example 31, which was formed from a material containing gold (Au) and niobium (Nb) in an atomic ratio of 90:10 with a film thickness of 45 nm and had a phase difference of 234 degrees, had an NILS of 2.74.

[0239] In addition, Example 32, which was formed from a material containing gold (Au) and titanium (Ti) in an atomic ratio of 65:35 with a film thickness of 47 nm and had a phase difference of 225 degrees, had an NILS of 2.69, and Example 33, which was formed from a material containing gold (Au) and titanium (Ti) in an atomic ratio of 85:15 with a film thickness of 46 nm and had a phase difference of 240 degrees, had an NILS of 2.75. In addition, Example 34, which was formed from a material containing gold (Au) and zirconium (Zr) in an atomic ratio of 70:30 with a film thickness of 51 nm and had a phase difference of 218 degrees, had an NILS of 2.67, and Example 35, which was formed from a material containing gold (Au) and zirconium (Zr) in an atomic ratio of 90:10 with a film thickness of 46 nm and had a phase difference of 248 degrees, had an NILS of 2.74.

[0240] In addition, Example 36, which was formed from a material containing iridium (Ir) and molybdenum (Mo) in an atomic ratio of 30:70 with a film thickness of 49 nm and had a phase difference of 209 degrees, had an NILS of 2.63, and Example 37, which was formed from a material containing iridium (Ir) and molybdenum (Mo) in an atomic ratio of 90:10 with a film thickness of 45 nm and had a phase difference of 227 degrees, had an NILS of 2.74. In addition, Example 38, which was formed from a material containing iridium (Ir) and tungsten (W) in an atomic ratio of 50:50 with a film thickness of 47 nm and had a phase difference of 225 degrees, had an NILS of 2.69, and Example 39, which was formed from a material containing iridium (Ir) and tungsten (W) in an atomic ratio of 90:10 with a film thickness of 46 nm and had a phase difference of 240 degrees, had an NILS of 2.75.

[0241] In addition, Example 40, which was formed from a material containing iridium (Ir) and niobium (Nb) in an atomic ratio of 50:50 with a film thickness of 47 nm and had a phase difference of 214 degrees, had an NILS of 2.68, and Example 41, which was formed from a material containing iridium (Ir) and niobium (Nb) in an atomic ratio of 90:10 with a film thickness of 46 nm and had a phase difference of 237 degrees, had an NILS of 2.76. In addition, Example 42, which was formed from a material containing iridium (Ir) and tantalum (Ta) in an atomic ratio of 85:15 with a film thickness of 45 nm and had a phase difference of 219 degrees, had an NILS of 2.71, and Example 43, which was formed from a material containing iridium (Ir) and tantalum (Ta) in an atomic ratio of 95:5 with a film thickness of 46 nm and had a phase difference of 248 degrees, had an NILS of 2.74.

[0242] In addition, Example 44, which was formed from a material containing iridium (Ir) and vanadium (V) in an atomic ratio of 65:35 with a film thickness of 45 nm and had a phase difference of 201 degrees, had an NILS of 2.6, and Example 45, which was formed from a material containing iridium (Ir) and vanadium (V) in an atomic ratio of 90:10 with a film thickness of 46 nm and had a phase difference of 240 degrees, had an NILS of 2.75. In addition, Example 46, which was formed from a material containing rhenium (Re) and molybdenum (Mo) in an atomic ratio of 45:55 with a film thickness of 48 nm and had a phase difference of 213 degrees, had an NILS of 2.65, and Example 47, which was formed from a material containing rhenium (Re) and molybdenum (Mo) in an atomic ratio of 90:10 with a film thickness of 47 nm and had a phase difference of 234 degrees, had an NILS of 2.75.

[0243] In addition, Example 48, which was formed from a material containing rhenium (Re) and tungsten (W) with a film thickness of 46 nm and an atomic ratio of 75:25, and had a phase difference of 216 degrees, had an NILS of 2.71, and Example 49, which was formed from a material containing rhenium (Re) and tungsten (W) with a film thickness of 46 nm and an atomic ratio of 95:5, and had a phase difference of 227 degrees, had an NILS of 2.74. In addition, Example 50, which was formed from a material containing rhenium (Re) and niobium (Nb) with an atomic ratio of 75:25 and had a phase difference of 213 degrees, had an NILS of 2.7, and Example 51, which was formed from a material containing rhenium (Re) and niobium (Nb) with a thickness of 46 nm and had an atomic ratio of 90:10 and had a phase difference of 224 degrees, had an NILS of 2.74.

[0244] Thus, even when the absorber layer 14 (absorber pattern layer 14a) was formed using a material containing elements from the third material group, which has a low refractive index n, as well as elements from the fourth material group, which has excellent processability and hydrogen resistance, a phase shift effect was obtained and resolution was improved. Furthermore, when the content of elements from the third material group was 20 atomic % or more of the total elements in the absorber layer 14, the NILS was good. Furthermore, when the combination of elements from the third material group and elements from the fourth material group contained in the absorber layer 14 was the same, the higher the content of elements from the third material group, the better the NILS.

[0245] The reflective photomask blank and reflective photomask of the present disclosure are not limited to the above-described embodiments and examples, and various modifications are possible within the scope that does not impair the features of the invention. [Industrial Applicability]

[0246] The reflective photomask blank and reflective photomask 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. [Explanation of symbols]

[0247] 11... Circuit board 12...Reflection layer 13…Protective layer 14...Absorption layer 14a...Absorption pattern (absorption pattern layer) 15...Back conductive film 16...Resist film 16a...Resist pattern 100...Reflective photomask blank 200...Reflective photomask

Claims

1. A substrate; a reflective layer having a multilayer film structure formed on the substrate and reflecting EUV light; a protective layer formed on the reflective layer to protect the reflective layer; and an absorption layer formed on the protective layer and configured to absorb EUV light, the absorbing layer has a phase difference in the range of 200 degrees or more and 280 degrees or less; a reflective photomask blank, characterized in that the absorption layer is made of a material containing RhAl, RuNb, RuAl, SnRuO, InRuO, TaTi, MoPd, IrPt, IrAu, RePt, ReAu, PtMo, PtNb, AuMo, AuNb, AuTi, AuZr, IrMo, IrW, IrNb, IrTa, IrV, ReMo, ReW, or ReNb.

2. 2. The reflective photomask blank according to claim 1, wherein the absorption layer has a phase difference in the range of 215 degrees or more and 270 degrees or less.

3. 2. The reflective photomask blank according to claim 1, wherein the absorbing layer has a phase difference in the range of 230 degrees or more and 260 degrees or less.

4. 2. The reflective photomask blank according to claim 1, wherein the absorbing layer has a refractive index n for EUV light that is smaller than 0.

93.

5. 2. The reflective photomask blank according to claim 1, wherein the absorbing layer has a refractive index n for EUV light that is smaller than 0.

92.

6. 2. The reflective photomask blank according to claim 1, wherein the absorber layer has a reflectance to EUV light in the range of 2% to 20%.

7. 2. The reflective photomask blank according to claim 1, wherein the absorber layer has a reflectance to EUV light in the range of 1.2% or more and 2.4% or less, or a reflectance to EUV light in the range of 11.0% or more and 17.0% or less.

8. A substrate; a reflective layer having a multilayer film structure formed on the substrate and reflecting EUV light; a protective layer formed on the reflective layer to protect the reflective layer; and an absorption pattern layer formed on the protective layer and absorbing EUV light, and having a pattern formed thereon; The absorbing pattern layer has a phase difference in the range of 200 degrees or more and 280 degrees or less, The reflective photomask is characterized in that the absorption pattern layer is made of a material containing RhAl, RuNb, RuAl, SnRuO, InRuO, TaTi, MoPd, IrPt, IrAu, RePt, ReAu, PtMo, PtNb, AuMo, AuNb, AuTi, AuZr, IrMo, IrW, IrNb, IrTa, IrV, ReMo, ReW, or ReNb.

9. 9. The reflective photomask according to claim 8, wherein the absorbing pattern layer has a phase difference in the range of 215 degrees to 270 degrees.

10. 9. The reflective photomask according to claim 8, wherein the absorbing pattern layer has a phase difference in the range of 230 degrees to 260 degrees.

11. 9. The reflective photomask according to claim 8, wherein the patterned absorbing layer has a refractive index n for EUV light that is less than 0.

93.

12. 9. The reflective photomask according to claim 8, wherein the patterned absorbing layer has a refractive index n for EUV light that is less than 0.

92.

13. 9. The reflective photomask according to claim 8, wherein the absorption pattern layer has a reflectance to EUV light in the range of 2% to 20%.

14. 9. The reflective photomask according to claim 8, wherein the absorption pattern layer has a reflectivity for EUV light in the range of 1.2% or more and 2.4% or less, or a reflectivity for EUV light in the range of 11.0% or more and 17.0% or less.

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