Method for manufacturing semiconductor device, and substrate

Abstract

To increase an amount of light of exposure with respect to a photoresist film.SOLUTION: A method for manufacturing a semiconductor device includes the step a) and the step b). The step a) includes depositing on a substrate a multilayer film where a first film containing a first material and a second film containing a second material whose index of refraction with respect to light used for exposure is lower than that of the first material are laminated alternately. The step b) includes depositing a photoresist film on an upper part of the multilayer film in the substrate.SELECTED DRAWING: Figure 15

Description

[Technical field]

[0001] Various aspects and embodiments of the present disclosure relate to a method for manufacturing a semiconductor device, and a substrate. [Background technology]

[0002] The following Patent Document 1 discloses a technique for laminating a multi-layer stack containing silicon and a non-metal on a substrate. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] US Patent Application Publication No. 2021 / 116799 Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides a method for manufacturing a semiconductor device, and a substrate, that can increase the amount of light exposed to a photoresist film. [Means for solving the problem]

[0005] A method for manufacturing a semiconductor device according to an embodiment of the present disclosure includes steps a) and b). In step a), a multilayer film is formed on a substrate, in which a first film containing a first material and a second film containing a second material having a lower refractive index for light used for exposure than the first material are alternately stacked. In step b), a photoresist film is formed on the upper part of the multilayer film on the substrate. Effect of the Invention

[0006] According to the present disclosure, the amount of light to be exposed to a photoresist film can be increased. [Brief description of the drawings]

[0007] [Figure 1A] FIG. 1A is a diagram illustrating an example of a conventional substrate. [Figure 1B] FIG. 1B is a diagram showing an example of changes in the transmittance and reflectance of the substrate shown in FIG. 1A. [Diagram 2] FIG. 2 is a diagram illustrating candidates for the first material and the second material that constitute the multilayer film. [Figure 3A] FIG. 3A is a diagram illustrating an example of a substrate according to an embodiment. [Figure 3B] FIG. 3B is a diagram showing an example of changes in the transmittance and reflectance of the substrate shown in FIG. 3A. [Figure 4A] FIG. 4A is a diagram illustrating an example of a substrate according to an embodiment. [Figure 4B] FIG. 4B is a diagram showing an example of changes in the transmittance and reflectance of the substrate shown in FIG. 4A. [Figure 5A] FIG. 5A is a diagram illustrating an example of a substrate according to an embodiment. [Figure 5B] FIG. 5B is a diagram showing an example of changes in the transmittance and reflectance of the substrate shown in FIG. 5A. [Figure 6A] FIG. 6A is a diagram illustrating an example of a substrate according to an embodiment. [Figure 6B] FIG. 6B is a diagram showing an example of changes in the transmittance and reflectance of the substrate shown in FIG. 6A. [Figure 7A] FIG. 7A is a diagram illustrating an example of a substrate according to an embodiment. [Figure 7B] FIG. 7B is a diagram showing an example of changes in the transmittance and reflectance of the substrate shown in FIG. 7A. [Figure 8A] FIG. 8A is a diagram illustrating an example of a substrate according to an embodiment. [Figure 8B] FIG. 8B is a diagram showing an example of changes in the transmittance and reflectance of the substrate shown in FIG. 8A. [Figure 9A] FIG. 9A is a diagram illustrating an example of a substrate according to an embodiment. [Figure 9B] FIG. 9B is a diagram showing an example of changes in the transmittance and reflectance of the substrate shown in FIG. 9A. [Figure 10A] FIG. 10A is a diagram illustrating an example of a substrate according to an embodiment. [Figure 10B]FIG. 10B is a diagram showing an example of a change in reflectance depending on the film thickness of one pair of substrates shown in FIG. 10A. [Figure 10C] FIG. 10C is a diagram showing an example of changes in the transmittance and reflectance of the substrate shown in FIG. 10A when the film thickness d is 7.0 nm. [Figure 10D] FIG. 10D is a diagram showing an example of the change in reflectance of the substrate shown in FIG. 10A when the film thickness d is 7.1 nm. [Figure 10E] FIG. 10E is a diagram showing an example of the change in reflectance of the substrate shown in FIG. 10A when the film thickness d is 7.15 nm. [Figure 11A] FIG. 11A is a diagram illustrating an example of a substrate according to an embodiment. [Figure 11B] FIG. 11B is a diagram showing an example of a change in reflectance depending on the film thickness of one pair of substrates shown in FIG. 11A. [Figure 12A] FIG. 12A is a diagram illustrating an example of a flow of exposure to a substrate according to an embodiment. [Figure 12B] FIG. 12B is a diagram illustrating an example of a flow of exposure of a substrate according to an embodiment. [Figure 12C] FIG. 12C is a diagram illustrating an example of a flow of exposure of a substrate according to an embodiment. [Figure 13A] FIG. 13A is a diagram showing an example of a change in reflectance due to a change in roughness of a substrate according to an embodiment. [Figure 13B] FIG. 13B is a diagram showing an example of a change in reflectance due to a change in roughness of the substrate according to the embodiment. [Figure 14A] FIG. 14A is a diagram showing an example of a change in reflectance due to a change in thickness of a photoresist film on a substrate according to an embodiment. [Figure 14B] FIG. 14B is a diagram showing an example of a change in reflectance due to a change in thickness of the SOG film of the substrate according to the embodiment. [Figure 15] FIG. 15 is a flowchart showing an example of a method for manufacturing a semiconductor device according to the embodiment. [Figure 16]FIG. 16 is a diagram illustrating an example of a flow of patterning included in the method for manufacturing a semiconductor device according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, embodiments of the method for manufacturing a semiconductor device and the substrate disclosed in the present application will be described in detail with reference to the drawings. Note that the method for manufacturing a semiconductor device and the substrate disclosed in the present application are not limited to the embodiments.

[0009] In the manufacture of semiconductor devices, a pattern is formed on a substrate such as a semiconductor wafer by a lithography process. In the lithography process, for example, a photoresist film is formed on a substrate, the formed photoresist film is selectively exposed through a mask on which a predetermined pattern is formed, and a development process is performed to form a pattern of a predetermined shape in the photoresist film.

[0010] In recent years, along with the miniaturization of semiconductor devices, lithography technology has also become more miniaturized. One method of miniaturization is shortening the wavelength of the exposure light source. In recent years, exposure has been performed using KrF excimer lasers and ArF excimer lasers. In addition, EUV lithography technology, which uses EUV (extreme ultraviolet) light with a shorter wavelength than these excimer lasers, is also being studied.

[0011] However, as semiconductor devices become finer, the width of the exposed portion of the photoresist film becomes smaller, and the amount of light imparted to the photoresist film decreases, resulting in an insufficient amount of exposure light.

[0012] Therefore, the present disclosure provides a technique for increasing the amount of light exposed to a photoresist film.

[0013] [Embodiment] An embodiment will be described. First, an example of conventional lithography will be described in brief with reference to FIG. 1A. FIG. 1A is a diagram for explaining an example of a conventional substrate W1. FIG. 1A shows the substrate W1. The substrate W1 has a silicon thermal oxide film 2, a metal hard mask 3, a SiO film 4, a SOC (Spin On Carbon) film 5, and a SOG (Spin on Glass) film 6 laminated in this order on a silicon substrate 1. The silicon thermal oxide film 2 has a thickness of, for example, 100 nm. The SiO film 4 has a thickness of, for example, 150 nm. The SOC film 5 has a thickness of, for example, 140 nm. The SOG film 6 has a thickness of, for example, 35 nm. The SOC film 5 can be, for example, an amorphous carbon film formed by spin coating. The SOG film 6 can be, for example, a SiO film formed by spin coating. Note that the configuration of the substrate W1 shown in FIG. 1A is merely an example, and is not limited thereto. When a semiconductor device is manufactured, films necessary for the manufacture of the semiconductor device are formed on the silicon substrate 1 as required.

[0014] A pattern is formed on such a substrate W1 by a lithography process. In the lithography process, a photoresist (PR) film 7 is formed on the substrate W1, and the formed photoresist film 7 is selectively exposed through a mask on which a predetermined pattern is formed, and then developed to form a pattern of a predetermined shape in the photoresist film 7. An example of the photoresist film 7 is a CH2 film. The thickness of the photoresist film 7 is, for example, 40 nm.

[0015] Incidentally, with the miniaturization of semiconductor devices, EUV exposure is being considered. In EUV exposure, the photoresist film 7 is exposed to light with a wavelength of 13.53 nm.

[0016] However, when the light with a wavelength of 13.53 nm used in EUV exposure is irradiated onto the substrate W1, most of the light does not contribute to the exposure of the photoresist film 7 and is absorbed by the substrate W1.

[0017] Here, in the embodiment, the transmittance and reflectance of EUV exposure light (light with a wavelength of 13.53 nm) were calculated for substrates of various configurations.

[0018] Fig. 1B is a diagram showing an example of changes in transmittance and reflectance of the substrate W1 shown in Fig. 1A. Fig. 1B shows changes in absorption A and reflectance R of the substrate W1 with respect to the incidence angle θ [deg] of light with a wavelength of 13.53 nm. As shown in Fig. 1B, the substrate W1 has a very high absorption A and a reflectance R of almost zero at any incidence angle θ.

[0019] Therefore, the present inventor has found a technique for increasing the amount of light for exposure to the photoresist film 7 by providing a multilayer film below the photoresist film 7 and reflecting light with the multilayer film. The multilayer film is formed by alternately laminating a first film containing a first material and a second film containing a second material having a lower refractive index than the first material for the light used for exposure. For example, the multilayer film is formed by alternately depositing a first film made of a first material having a relatively high refractive index for the light used for exposure and a second film made of a second material having a relatively low refractive index.

[0020] Candidates for the first and second materials constituting the multilayer film will be explained. Figure 2 is a diagram for explaining candidates for the first and second materials constituting the multilayer film. In Figure 2, each material is plotted according to the extinction coefficient k and the refractive index n of each material for light with a wavelength of 13.53 nm used for EUV exposure.

[0021] When the light used for exposure is light with a wavelength of 13.53 nm used for EUV exposure, the first material is preferably a material with an extinction constant k smaller than 0.035 and a refractive index n larger than 0.945. The first material is preferably a material surrounded by an ellipse C1 in FIG. 2. For example, the first material may be any of Si, SiC, B4C, BN, and Ti. Even when Si, SiC, B4C, BN, and Ti become oxides or nitrides, the extinction constant k and refractive index n are approximately the same. Therefore, the first material may be any of oxides or nitrides of Si, SiC, B4C, BN, and Ti.

[0022] The second material is preferably a material having an extinction constant k smaller than 0.035 and a refractive index n smaller than 0.938. The second material is preferably a material surrounded by an ellipse C2 in FIG. 2. For example, any of Rh, Ru, Mo, and Nb can be used as the second material. Even when Rh, Ru, Mo, and Nb are in the form of an oxide or nitride, the extinction constant k and the refractive index n are approximately the same. Therefore, any of oxides or nitrides of Rh, Ru, Mo, and Nb can be used as the second material.

[0023] For example, in the case of the substrate W1 shown in FIG. 1A, the multilayer film is provided between the photoresist film 7 and the SOG film 6, or between the SOG film 6 and the SOC film 5.

[0024] 3A is a diagram for explaining an example of a substrate W2 according to an embodiment. In FIG. 3A, the substrate W2 is shown. The substrate W2 shows a case where a multilayer film 10 is provided between the photoresist film 7 and the SOG film 6 of the substrate W1 shown in FIG. 1A. The substrate W2 has a silicon thermal oxide film 2, a metal hard mask 3, a SiO film 4, a SOC film 5, a SOG film 6, a multilayer film 10, and a photoresist film 7 laminated in this order on a silicon substrate 1. In FIG. 3A, the multilayer film 10 is formed by using Si as the first material and Nb as the second material, and 20 pairs are formed, with one Si film and one Nb film as one pair.

[0025] For the substrate W2, the transmittance and reflectance were calculated when the thickness of the Si film was set to 4 nm, the thickness of the Nb film was set to 3 nm, and the thickness of the pair of the Si film and the Nb film was set to 7 nm. Figure 3B is a diagram showing an example of the change in the transmittance and reflectance of the substrate W2 shown in Figure 3A. Figure 3B shows the change in the absorption A and reflectance R of the substrate W2 with respect to the incident angle θ [deg] of light with a wavelength of 13.53 nm.

[0026] As shown in FIG. 3B, the reflectance R of the substrate W2 is increased by providing the multilayer film 10 between the photoresist film 7 and the SOG film 6, and a reflectance R of about 45% is obtained when the incident angle θ is about 0 to 8°.

[0027] In this way, by providing the multilayer film 10 between the photoresist film 7 and the SOG film 6, the substrate W2 can reflect light by the multilayer film 10, so that the amount of light exposed to the photoresist film 7 can be increased.

[0028] 4A is a diagram for explaining an example of a substrate W3 according to an embodiment. In FIG. 4A, the substrate W3 is shown. The substrate W3 shows a case where a multilayer film 10 is provided between the SOG film 6 and the SOC film 5 of the substrate W1 shown in FIG. 1A. The substrate W3 has a silicon thermal oxide film 2, a metal hard mask 3, a SiO film 4, a SOC film 5, a multilayer film 10, a SOG film 6, and a photoresist film 7 laminated in this order on a silicon substrate 1. In FIG. 4A, the multilayer film 10 is formed by using Si as the first material and Nb as the second material, and 20 pairs are formed, with one Si film and one Nb film as one pair.

[0029] For the substrate W3, the transmittance and reflectance were calculated when the thickness of the Si film was set to 4 nm, the thickness of the Nb film was set to 3 nm, and the thickness of the pair of the Si film and the Nb film was set to 7 nm. Figure 4B is a diagram showing an example of the change in the transmittance and reflectance of the substrate W3 shown in Figure 4A. Figure 4B shows the change in the absorption A and reflectance R of the substrate W3 with respect to the incident angle θ [deg] of light with a wavelength of 13.53 nm.

[0030] As shown in FIG. 4B, the reflectance R of the substrate W3 is increased by providing the multilayer film 10 between the SOG film 6 and the SOC film 5, and a reflectance R of about 27% is obtained when the incident angle θ is about 0 to 10°.

[0031] In this manner, by providing the multilayer film 10 between the SOG film 6 and the SOC film 5, the substrate W3 can reflect light by the multilayer film 10, and therefore the amount of light to be exposed to the photoresist film 7 can be increased.

[0032] Next, an example in which the materials to be laminated in the multilayer film 10 and the number of pairs to be laminated are changed will be described.

[0033] FIG. 5A is a diagram for explaining an example of the substrate W4 according to the embodiment. FIG. 5A shows the substrate W4. The substrate W4 shows a case where a multilayer film 10 is provided between the SOG film 6 and the SOC film 5 of the substrate W1 shown in FIG. 1A. The substrate W4 has a silicon thermal oxide film 2, a metal hard mask 3, a SiO film 4, an SOC film 5, a multilayer film 10, an SOG film 6, and a photoresist film 7 laminated in this order on a silicon substrate 1. In FIG. 5A, the multilayer film 10 is formed by using Si as the first material and Ru as the second material, and 40 pairs are formed, each pair consisting of one Si film and one Ru film. In FIG. 5A, the thickness of the SOG film 6 is, for example, 5 nm.

[0034] For the substrate W4, the transmittance and reflectance were calculated when the thickness of the Si film was set to 4 nm, the thickness of the Ru film was set to 3 nm, and the thickness of the pair of the Si film and the Ru film was set to 7 nm. Figure 5B is a diagram showing an example of the change in the transmittance and reflectance of the substrate W4 shown in Figure 5A. Figure 5B shows the change in the absorption A and reflectance R of the substrate W4 with respect to the incident angle θ [deg] of light with a wavelength of 13.53 nm.

[0035] As shown in FIG. 5B, substrate W4 has an increased reflectance R due to an increased number of pairs in multilayer film 10, and a reflectance R of about 50% can be obtained when the angle of incidence θ is about 0 to 8°.

[0036] In this manner, by providing the multilayer film 10 between the SOG film 6 and the SOC film 5, the substrate W4 can reflect light by the multilayer film 10, and therefore the amount of light to which the photoresist film 7 is exposed can be increased.

[0037] Fig. 6A is a diagram illustrating an example of a substrate W5 according to an embodiment. Substrate W5 is shown in Fig. 6A. Substrate W5 shows a case where the number of pairs in the multilayer film 10 of substrate W4 is 10 pairs.

[0038] For the substrate W5, the transmittance and reflectance were calculated when the thickness of the Si film was set to 4 nm, the thickness of the Ru film was set to 3 nm, and the thickness of the pair of the Si film and the Ru film was set to 7 nm. Figure 6B is a diagram showing an example of the change in the transmittance and reflectance of the substrate W5 shown in Figure 6A. Figure 6B shows the change in the absorption A and reflectance R of the substrate W5 with respect to the incident angle θ [deg] of light with a wavelength of 13.53 nm.

[0039] As shown in FIG. 6B, although the reflectance R of substrate W5 is reduced by reducing the number of pairs in multilayer film 10 to 10, a reflectance R of about 35% is obtained when the incident angle θ is about 0 to 8°.

[0040] Fig. 7A is a diagram illustrating an example of a substrate W6 according to an embodiment. Substrate W5 is shown in Fig. 7A. Substrate W6 shows a case where the number of pairs in the multilayer film 10 of substrate W4 is five.

[0041] For the substrate W6, the transmittance and reflectance were calculated when the thickness of the Si film was set to 4 nm, the thickness of the Ru film was set to 3 nm, and the thickness of the pair of the Si film and the Ru film was set to 7 nm. Figure 7B is a diagram showing an example of the change in the transmittance and reflectance of the substrate W6 shown in Figure 7A. Figure 7B shows the change in the absorption A and reflectance R of the substrate W6 with respect to the incident angle θ [deg] of light with a wavelength of 13.53 nm.

[0042] As shown in FIG. 7B, although the reflectance R of substrate W6 is reduced by reducing the number of pairs in multilayer film 10 to five pairs, a reflectance R of about 15% can be obtained over a wide range of incident angles θ.

[0043] In this way, since the multilayer film 10 can reflect light even when the number of pairs is small, the amount of light to be exposed to the photoresist film 7 can be increased.

[0044] The multilayer film 10 reflects light at the interface between the first film made of the first material and the second film made of the second material. Therefore, if the multilayer film 10 has at least one pair of the first film and the second film laminated thereon, the amount of light to be exposed to the photoresist film 7 can be increased. Even if the number of pairs of the multilayer film 10 is increased, the increase in reflectance is saturated. Therefore, in order to obtain a high reflectance while suppressing the film thickness of the multilayer film 10, the number of pairs of the multilayer film 10 is preferably 1 to 60, and more preferably 5 to 40. In addition, the multilayer film 10 may have the first film and the second film laminated alternately, and the number of layers of the first film and the second film may not be the same. For example, the multilayer film 10 may have a configuration in which the first film and the second film are laminated alternately so that either the first film or the second film is the uppermost surface or the lowermost surface of the laminate.

[0045] Next, an example in which the laminated materials of the multilayer film 10 are changed will be described.

[0046] FIG. 8A is a diagram for explaining an example of a substrate W7 according to an embodiment. FIG. 8A shows the substrate W7. The substrate W7 shows a case where a multilayer film 10 is provided between the SOG film 6 and the SOC film 5 of the substrate W1 shown in FIG. 1A. The substrate W7 has a silicon thermal oxide film 2, a metal hard mask 3, a SiO film 4, an SOC film 5, a multilayer film 10, an SOG film 6, and a photoresist film 7 laminated in this order on a silicon substrate 1. In FIG. 8A, the multilayer film 10 is formed by using B4C as the first material and Ru as the second material, and 40 pairs are formed, each pair consisting of one B4C film and one Ru film. In FIG. 8A, the thickness of the SOG film 6 is, for example, 5 nm.

[0047] For the substrate W7, the transmittance and reflectance were calculated when the thickness of the Ru film was 3.09 nm, the thickness of the B4C film was 4.11 nm, and the thickness of the pair of the Ru film and the B4C film was 7.2 nm. Figure 8B is a diagram showing an example of the change in the transmittance and reflectance of the substrate W7 shown in Figure 8A. Figure 8B shows the change in the absorption A and reflectance R of the substrate W7 with respect to the incident angle θ [deg] of light with a wavelength of 13.53 nm.

[0048] As shown in FIG. 8B, even when the first material of the multilayer film 10 is B4C and the second material is Ru, the reflectance R of the substrate W7 is increased by the multilayer film 10, and a reflectance R of about 35% is obtained when the incident angle θ is about 0 to 8°.

[0049] In this way, even when the first material of the multilayer film 10 is B4C and the second material is Ru, the substrate W7 can reflect light by the multilayer film 10, so that the amount of light exposed to the photoresist film 7 can be increased.

[0050] FIG. 9A is a diagram for explaining an example of a substrate W8 according to an embodiment. FIG. 9A shows the substrate W8. The substrate W8 shows a case where a multilayer film 10 is provided between the SOG film 6 and the SOC film 5 of the substrate W1 shown in FIG. 1A. The substrate W8 has a silicon thermal oxide film 2, a metal hard mask 3, a SiO film 4, an SOC film 5, a multilayer film 10, an SOG film 6, and a photoresist film 7 laminated in this order on a silicon substrate 1. In FIG. 8A, the multilayer film 10 is formed by using BN as the first material and Ru as the second material, with 40 pairs of one BN film and one Ru film as one pair. In FIG. 9A, the thickness of the SOG film 6 is, for example, 5 nm.

[0051] For the substrate W8, the transmittance and reflectance were calculated when the thickness of the Ru film was 3.09 nm, the thickness of the BN film was 4.11 nm, and the thickness of the pair of the Ru film and the BN film was 7.2 nm. Figure 9B is a diagram showing an example of the change in the transmittance and reflectance of the substrate W8 shown in Figure 9A. Figure 9B shows the change in the absorption A and reflectance R of the substrate W8 with respect to the incident angle θ [deg] of light with a wavelength of 13.53 nm.

[0052] As shown in FIG. 9B, even when the first material of the multilayer film 10 is BN and the second material is Ru, the reflectance R of the substrate W8 is increased by the multilayer film 10, and a reflectance R of about 30% is obtained when the incident angle θ is about 0 to 7°.

[0053] In this way, even when the first material of the multilayer film 10 is BN and the second material is Ru, the substrate W8 can reflect light by the multilayer film 10, so that the amount of light exposed to the photoresist film 7 can be increased.

[0054] Here, the multilayer film 10 is configured by alternately laminating the first material and the second material, and the reflectance also changes depending on the film thickness of a pair of the first film made of the first material and the second film made of the second material. The reflectance of the multilayer film 10 also changes depending on the ratio of the film thicknesses of the first film and the second film for a pair of the first film made of the first material and the second film made of the second material. In the above-mentioned embodiment, the ratio of the film thicknesses of the first film and the second film for a pair of the multilayer film 10 is set to a ratio that provides the highest reflectance, and the reflectance is calculated.

[0055] Next, an example will be described in which the film thickness of one pair of the first film made of the first material and the second film made of the second material in the multilayer film 10 is changed.

[0056] FIG. 10A is a diagram for explaining an example of a substrate W9 according to an embodiment. FIG. 10A shows the substrate W9. The substrate W9 shows a case where a multilayer film 10 is provided between the SOG film 6 and the SOC film 5 of the substrate W1 shown in FIG. 1A. The substrate W9 has a silicon thermal oxide film 2, a metal hard mask 3, a SiO film 4, an SOC film 5, a multilayer film 10, an SOG film 6, and a photoresist film 7 laminated in this order on a silicon substrate 1. In FIG. 10A, the multilayer film 10 is formed by using Si as the first material and Mo as the second material, and 20 pairs are formed, with one Si film and one Mo film as one pair. In FIG. 10A, the thickness of the SOG film 6 is, for example, 5 nm.

[0057] For the substrate W9, the transmittance and reflectance were calculated by changing the film thickness of one pair of the Si film and Mo film of the multilayer film 10. FIG. 10B is a diagram showing an example of the change in reflectance according to the film thickness of one pair of the substrate W9 shown in FIG. 10A. In FIG. 10B, the vertical axis is the film thickness d of one pair of the Si film and Mo film of the multilayer film 10, and the vertical axis is the incident angle θ [deg] of light with a wavelength of 13.53 nm, and the reflectance corresponding to the incident angle θ is shown by a line with the same reflectance value. FIG. 10B shows the reflectance value corresponding to the incident angle θ when the film thickness of one pair is 7.0 to 7.3 nm. For example, when the film thickness d of one pair is 7.0 nm, a reflectance of 43.3% (=0.433) or more is obtained when the incident angle θ is about 0 to 11°. In FIG. 10B, cases where the film thickness of one pair is less than 7.0 nm or more than 7.3 nm are omitted, but when the incident angle θ is in the range of 0 to 5°, the film thickness of one pair is preferably 6.0 to 8.0 nm, and more preferably 6.67 to 7.34 nm in order to obtain a reflectance of 5% or more.

[0058] Fig. 10C is a diagram showing an example of changes in transmittance and reflectance of the substrate W9 shown in Fig. 10A when the film thickness d is 7.0 nm. Fig. 10C shows changes in absorption A and reflectance R with respect to the incident angle θ [deg] of light with a wavelength of 13.53 nm for the substrate W9 when the film thickness d is 7.0 nm.

[0059] Fig. 10D is a diagram showing an example of a change in reflectance of the substrate W9 shown in Fig. 10A when the film thickness d is 7.1 nm. Fig. 10D shows a change in reflectance R with respect to the incident angle θ [deg] of light with a wavelength of 13.53 nm for the substrate W9 when the film thickness d is 7.1 nm.

[0060] Fig. 10E is a diagram showing an example of a change in reflectance of the substrate W9 shown in Fig. 10A when the film thickness d is 7.15 nm. Fig. 10E shows a change in reflectance R with respect to the incident angle θ [deg] of light with a wavelength of 13.53 nm for the substrate W9 when the film thickness d is 7.15 nm.

[0061] As shown in Fig. 10C, when the film thickness d is 7.0 nm, a reflectance of about 45% is obtained when the incident angle θ is about 0 to 8°. On the other hand, as shown in Fig. 10D, when the film thickness d is 7.1 nm, the reflectance is higher when the incident angle θ is near 10° than when the incident angle θ is 0°. Also, as shown in Fig. 10E, when the film thickness d is 7.15 nm, the reflectance is higher when the incident angle θ is near 10 to 12° than when the incident angle θ is 0°.

[0062] FIG. 11A is a diagram for explaining an example of a substrate W10 according to an embodiment. FIG. 11A shows the substrate W10. The substrate W10 shows a case where a multilayer film 10 is provided between the SOG film 6 and the SOC film 5 of the substrate W1 shown in FIG. 1A. The substrate W10 has a silicon thermal oxide film 2, a metal hard mask 3, a SiO film 4, an SOC film 5, a multilayer film 10, an SOG film 6, and a photoresist film 7 laminated in this order on a silicon substrate 1. In FIG. 11A, the multilayer film 10 is formed by using Ti as the first material and Ru as the second material, and 20 pairs are formed, each pair consisting of one Ti film and one Ru film. In FIG. 11A, the thickness of the SOG film 6 is, for example, 5 nm.

[0063] For the substrate W10, the transmittance and reflectance were calculated by changing the film thickness of one pair of Ti and Ru films of the multilayer film 10. FIG. 11B is a diagram showing an example of the change in reflectance according to the film thickness of one pair of the substrate W10 shown in FIG. 11A. In FIG. 11B, the vertical axis is the film thickness d of one pair of Ti and Ru films of the multilayer film 10, and the vertical axis is the incident angle θ [deg] of light with a wavelength of 13.53 nm, and the reflectance corresponding to the incident angle θ is shown by a line with the same reflectance value. FIG. 11B shows the value of the reflectance corresponding to the incident angle θ when the film thickness of one pair is 7.0 to 9.0 nm. For example, when the film thickness d of one pair is 7.4 nm, a reflectance of 15.7% (=0.157) or more is obtained when the incident angle θ is about 0 to 12°.

[0064] In this way, the reflectance of the multilayer film 10 changes depending on the film thickness of one pair of the first film made of the first material and the second film made of the second material. Also, the reflectance of the multilayer film 10 with respect to the incident angle θ changes depending on the film thickness of one pair. By adjusting the film thickness of one pair of the multilayer film 10, it is possible to control which light at which incident angle θ is reflected more and which is absorbed more. This allows fine exposure to be achieved.

[0065] For example, FIG. 11A shows the incidence angle θ [deg] of light when exposing the substrate W10. In the lithography process, light is incident from above the substrate W10 to expose the photoresist film 7. As semiconductor devices become finer, the numerical aperture (NA) of the exposure tool increases, and the incidence angle θ of light to the substrate W10 also becomes wider. For example, in an EUV exposure tool manufactured by ASML in the Netherlands, when the numerical aperture is 0.33, the incidence angle θ is 19.3°, and when the numerical aperture is 0.55, the incidence angle θ is 33.4°. In addition, it is planned to further increase the numerical aperture of the EUV exposure tool, and when the numerical aperture is 0.7, the incidence angle θ is 44.4°.

[0066] 12A to 12C are diagrams for explaining an example of the flow of exposure to the substrate W10 according to the embodiment. FIG. 12A shows EUV light incident on the substrate W10. The numerical aperture of the exposure apparatus has increased, and the incidence angle θ has also become wider. Here, for example, the film thickness of one pair of the multilayer film 10 is adjusted so as to reflect a large amount of EUV light incident on the substrate W10 from a vertical direction (incident angle θ=0°). For example, the film thickness of one pair is adjusted to a film thickness at which the reflectance of light incident on the substrate W10 from a vertical direction is high, and the reflectance decreases as the incident angle from the vertical direction increases. For example, when mainly reflecting EUV light incident vertically, the film thickness of one pair is preferably 7.0 to 7.6 nm, more preferably 7.1 to 7.4 nm.

[0067] FIG. 12B shows the EUV light reflected by the multilayer film 10. This increases the amount of EUV light at the center of the exposed portion of the photoresist film 7. Also, diffusion of the EUV light incident at a large incidence angle θ can be suppressed. FIG. 12C shows an area 7A exposed by the incident and reflected EUV light. The photoresist film 7 is exposed to a large amount of EUV light in the area 7A that is hit by the EUV light incident from a vertical direction. This allows fine exposure of the photoresist film 7 to be achieved in accordance with the mask.

[0068] In the above embodiment, the transmittance and reflectance are calculated without considering the influence of roughness at the interface between the multilayer film 10 and the upper layer (photoresist film 7 or SOG film 6) and between the first film and the second film laminated in the multilayer film 10. Therefore, an example in which the transmittance and reflectance are calculated while considering the influence of roughness at the interface between the multilayer film 10 and the upper layer and between the first film and the second film laminated in the multilayer film 10 will be described.

[0069] For the substrate W10 shown in FIG. 11A, the reflectance was calculated by changing the roughness of the interface between the multilayer film 10 and the SOG film 6. The reflectance was calculated under the conditions that the thickness of the Ru film was 3.49 nm, the thickness of the Ti film was 3.86 nm, and light with a wavelength of 13.53 nm was incident at an incident angle θ=10°. FIG. 13A is a diagram showing an example of the change in reflectance due to the change in roughness of the substrate W10 according to the embodiment. FIG. 13A shows the change in reflectance R with respect to the roughness of the interface between the multilayer film 10 and the SOG film 6 when light with a wavelength of 13.53 nm is incident on the substrate W10 at an incident angle θ=10°.

[0070] In addition, for the substrate W10 shown in FIG. 11A, the reflectance was calculated by changing the roughness of the interface between the Ti film and the Ru film stacked on the multilayer film 10. The reflectance was calculated under the conditions that the thickness of the Ru film was 3.49 nm, the thickness of the Ti film was 3.86 nm, and light with a wavelength of 13.53 nm was incident at an incident angle θ=10°. FIG. 13B is a diagram showing an example of the change in reflectance due to the change in roughness of the substrate W10 according to the embodiment. FIG. 13B shows the change in reflectance R with respect to the roughness of the interface between the Ti film and the Ru film stacked on the multilayer film 10 when light with a wavelength of 13.53 nm is incident on the substrate W10 at an incident angle θ=10°.

[0071] As shown in FIG. 13A, the reflectance R decreases as the roughness of the interface between the multilayer film 10 and the SOG film 6 increases. Also, as shown in FIG. 13B, the reflectance R decreases as the roughness of the interface between the Ti film and the Ru film stacked on the multilayer film 10 increases. Therefore, it is preferable to reduce the roughness of the interface between the multilayer film 10 and the SOG film 6 and the interface between the Ti film and the Ru film stacked on the multilayer film 10. For example, the roughness of the interface between the multilayer film 10 and the SOG film 6 and the interface between the Ti film and the Ru film stacked on the multilayer film 10 is preferably 1 nm or less, more preferably 0.5 nm or less. In order to suppress the roughness, a nitrided layer, an oxide layer, or a barrier layer made of B4C having a low relative dielectric constant may be provided at the interface between the multilayer film 10 and the SOG film 6 and the interface between the Ti film and the Ru film stacked on the multilayer film 10.

[0072] Incidentally, the multilayer film 10 may have an interference effect with the upper layers (photoresist film 7, SOG film 6), and the reflectance may change depending on the film thickness of the upper layer. Therefore, an example will be described in which the transmittance and reflectance are calculated by taking into account the interference effect between the multilayer film 10 and the upper layers.

[0073] For the substrate W10 shown in FIG. 11A, the film thickness of the photoresist film 7 was changed and the reflectance was calculated. The reflectance was calculated under the conditions that the Ru film was 3.49 nm thick, the Ti film was 3.86 nm thick, and light with a wavelength of 13.53 nm was incident at an incident angle θ=10°. FIG. 14A is a diagram showing an example of the change in reflectance due to the change in film thickness of the photoresist film 7 of the substrate W10 according to the embodiment. FIG. 14A shows the change in reflectance R with respect to the film thickness of the photoresist film 7 when light with a wavelength of 13.53 nm is incident on the substrate W10 at an incident angle θ=0°.

[0074] In addition, the reflectance was calculated by changing the thickness of the SOG film 6 for the substrate W10 shown in FIG. 11A. The reflectance was calculated under the conditions that the thickness of the Ru film was 3.49 nm, the thickness of the Ti film was 3.86 nm, and light with a wavelength of 13.53 nm was incident at an incident angle θ=0°. FIG. 14B is a diagram showing an example of the change in reflectance due to the change in the thickness of the SOG film 6 of the substrate W10 according to the embodiment. FIG. 14B shows the change in reflectance R with respect to the thickness of the SOG film 6 when light with a wavelength of 13.53 nm is incident on the substrate W10 at an incident angle θ=0°.

[0075] As shown in FIG. 14A, when the thickness of the photoresist film 7 increases, the reflectance tends to decrease overall while repeating periodic increases and decreases due to the interference effect. Also, as shown in FIG. 14B, when the thickness of the SOG film 6 increases, the reflectance tends to decrease overall while repeating periodic increases and decreases due to the interference effect. Therefore, it is preferable that the photoresist film 7 and the SOG film 6 are thin. For example, the photoresist film 7 is preferably 40 nm or less. The SOG film 6 is also preferably 40 nm or less. Also, the thicknesses of the photoresist film 7 and the SOG film 6 are preferably such that the reflectance increases in the periodic increase and decrease of the reflectance due to the interference effect. For example, the thicknesses of the photoresist film 7 and the SOG film 6 are preferably such that the reflectance becomes maximum in the periodic increase and decrease of the reflectance due to the interference effect.

[0076] Next, an example of a method for manufacturing a semiconductor device according to an embodiment will be described. First, as a part of the method for manufacturing a semiconductor device, a flow of forming each layer on a substrate will be described. Fig. 15 is a flow chart showing an example of a flow of film formation included in the method for manufacturing a semiconductor device according to an embodiment.

[0077] A thermal oxidation process is performed on the silicon substrate 1 to form a silicon thermal oxide film 2 on the silicon substrate 1 (step S10). Next, a metal hard mask 3 is formed on the silicon substrate 1 by, for example, PVD (Physical Vapor Deposition) or the like (step S11). As a result, the metal hard mask 3 is formed on the silicon thermal oxide film 2.

[0078] Next, the SOC film 5 is formed on the silicon substrate 1 (step S12). For example, an amorphous carbon film is formed as the SOC film 5 by spin coating. In this way, the SOC film 5 is formed on the metal hard mask 3. Note that, when the SiO film 4 is provided between the metal hard mask 3 and the SOC film 5, the SiO film 4 is formed on the silicon substrate 1 between steps S11 and S12.

[0079] Next, the multilayer film 10 is formed on the silicon substrate 1 (step S13). For example, the multilayer film 10 is formed by alternately forming a first film containing a first material and a second film containing a second material whose refractive index n for light used for exposure is lower than that of the first material by PVD film formation or ALD (Atomic Layer Deposition) on the silicon substrate 1. For example, when forming the Ru / Si multilayer film 10 by PVD film formation, the film is formed at a pressure of about 0.1 to 10 Pa using a process gas such as Ar. The film formation time, input power, etc. are adjusted to adjust the designed film thickness. It is also effective to add nitrogen or oxygen during film formation and perform reactive sputtering. For example, interlayer diffusion can be controlled by slightly nitrifying the Si upper layer. Also, for example, when forming the Ru / Si multilayer film 10 by ALD, a precursor appropriate for the film formation of Ru / Si is selected. Also, the number of cycles of ALD for each of Ru / Si is adjusted so that the film thickness of Ru / Si becomes the designed film thickness. Then, the ALD film formation is alternately performed with the adjusted number of Ru / Si cycles to form the Ru / Si multilayer film 10. In this way, the multilayer film 10 is formed on the SOC film 5. In step S13, in order to suppress roughness at the interface between the first film and the second film stacked in the multilayer film 10, a nitrided layer, an oxide layer, or a barrier layer made of a material with a low dielectric constant (e.g., B4C) may be formed between the first film and the second film.

[0080] Next, an SOG film 6 is formed on the silicon substrate 1 (step S14). For example, a SiO film is formed as the SOG film 6 by spin coating. In this way, the SOG film 6 is formed on the multilayer film 10. In order to suppress a decrease in reflectance, the thickness of the SOG film 6 is preferably 40 nm or less. In step S14, it is also preferable to form the SOG film 6 with a thickness that increases the reflectance in the periodic increase and decrease in reflectance due to the interference effect.

[0081] Next, a photoresist film 7 is formed on the silicon substrate 1 by, for example, spin coating (step S15). As a result, the photoresist film 7 is formed on the SOG film 6. In order to suppress a decrease in reflectance, the thickness of the photoresist film 7 is preferably 40 nm or less. In addition, in step S15, it is preferable to form the photoresist film 7 with a thickness that increases the reflectance in the periodic increase and decrease in reflectance due to the interference effect. In addition, in step S15, in order to suppress roughness at the interface between the SOG film 6 and the photoresist film 7, any of a nitrided layer, an oxide layer, and a barrier layer made of a material with a low relative dielectric constant (for example, B4C) may be formed between the SOG film 6 and the photoresist film 7.

[0082] In addition, when the multilayer film 10 is provided between the photoresist film 7 and the SOG film 6 as in the case of the substrate W2 shown in FIG. 3A, the processing order of steps S13 and S14 is reversed.

[0083] Next, as a part of the semiconductor device manufacturing method, a flow of patterning a substrate including a lithography process will be described. FIG. 16 is a diagram for explaining an example of a flow of patterning included in the semiconductor device manufacturing method according to the embodiment. FIG. 16 shows a flow of patterning a substrate W11 in (A) to (I). As shown in FIG. 16(A), the substrate W11 is formed by sequentially stacking a silicon thermal oxide film 2, a metal hard mask 3, an SOC film 5, a multilayer film 10, an SOG film 6, and a photoresist film 7 on a silicon substrate 1. Since the SiO film 4 is etched when the SOC film 5 is etched, the SiO film 4 is not shown in FIG. 16 and is collectively shown as the SOC film 5. In FIG. 16, the multilayer film 10 is formed in a plurality of pairs, with the first material being Si and the second material being Ru, with one Si film and one Ru film being one pair. The substrate W11 may be configured to have a SiN film or a SiC film stacked instead of the SOG film 6. In addition, when the adhesion of the photoresist film 7 to the substrate W11 is an issue, the SOG film 6 may be configured to be a combination of a SiO film and a SiC film, a SiO film and a SiN film, or a SiC film and a SiN film.

[0084] In the manufacture of a semiconductor device, the substrate W11 is exposed by EUV exposure. As a result, in the substrate W11, the region 7A of the photoresist film 7 is exposed by the incident and reflected EUV light as shown in FIG. 16(B). After the exposure, the substrate W11 is pre-baked (PEB) and the photoresist film 7 is developed. The exposed region 7A of the photoresist film 7 is removed by the development, and a resist pattern 7b of the photoresist film 7 is formed as shown in FIG. 16(C). Using the resist pattern 7b as a mask, the SOG film 6 is etched as shown in FIG. 16(D). The SOG film 6 can be etched by, for example, a fluorine-containing gas. Then, using the SOG film 6 as a mask, the multilayer film 10 is etched as shown in FIG. 16(E). The Si film of the multilayer film 10 can be etched by, for example, Cl gas, O2 gas, or the like. The Ru film of the multilayer film 10 can be etched by, for example, Cl gas, or the like. The multilayer film 10 can be etched by alternately repeating etching of the Si film and the Ru film.

[0085] Then, the SOC film 5 is etched using the multilayer film 10 as a mask, as shown in FIG. 16(F). Then, the multilayer film 10 is removed, and the metal hard mask 3 is etched using the SOC film 5 as a mask, as shown in FIG. 16(G). The multilayer film 10 may be removed together with the etching gas for the metal hard mask 3. Also, for example, when a metal hard mask such as IGZO that is resistant to Cl gas or O2 gas is used as the metal hard mask 3, the multilayer film 10 may be etched and removed after the patterning of the metal hard mask 3 is completed. IGZO is an oxide semiconductor made of indium (In), gallium (Ga), and zinc (Zn).

[0086] Then, using the metal hard mask 3 as a mask, the silicon thermal oxide film 2 is etched as shown in FIG. 16(H). Then, as shown in FIG. 16(I), the metal hard mask 3 is removed. By patterning the substrate W11 in this manner, the pattern formed in the photoresist film 7 by EUV exposure can be transferred to the silicon thermal oxide film 2. Note that, although FIG. 16 shows an example in which a pattern is formed in the silicon thermal oxide film 2, this silicon thermal oxide film 2 may be a TEOS (CVD SiO2), SiN, or low-k film.

[0087] In order to obtain a high reflectance, it is preferable that the refractive indexes n of the first and second materials alternately stacked in the multilayer film 10 are far apart. For example, the multilayer film 10 can obtain a high reflectance by using Si as the first material and Ru as the second material, and stacking Si films and Ru films alternately. In addition, in consideration of processing, it is preferable that the multilayer film 10 is configured to use Si as the first material and Mo as the second material, and stack Si films and Mo films alternately. The multilayer film 10 configured to stack Si films and Mo films alternately can be etched with Cl2 gas with good selectivity to the mask of the SOG film 6.

[0088] In addition, in the patterning of semiconductor devices, a metal oxide resist (Metal Ox Resist) may be used as a mask instead of the SOG film 6 and the photoresist film 7. When using a metal oxide resist, it is preferable that the multilayer film 10 is configured to have a first material of Si or Mo and a second material of Ru, with Si or Mo films and Ru films alternately laminated. The multilayer film 10 configured to have Si or Mo films and Ru films alternately laminated can be etched with Cl2 gas at a good selectivity with respect to the metal oxide resist mask. The metal oxide resist can be removed with HBr gas.

[0089] The above describes the embodiment. As described above, the method for manufacturing a semiconductor device in the above embodiment includes step a) (e.g., step S13) and step b) (e.g., step S15). In step a, a multilayer film 10 is formed on a substrate W (general term for substrates W2 to W11) by alternately stacking a first film containing a first material and a second film containing a second material whose refractive index n to light used for exposure is lower than that of the first material. In step b), a photoresist film 7 is formed on an upper portion of the multilayer film 10 on the substrate W. This allows light to be reflected by the multilayer film 10, so that the amount of light for exposure to the photoresist film 7 can be increased.

[0090] Moreover, the light used for exposure is light of a wavelength used for EUV exposure. The first material is a material having an extinction constant k smaller than 0.035 and a refractive index larger than 0.945 with respect to the EUV exposure light. The second material is a material having an extinction constant k smaller than 0.035 and a refractive index smaller than 0.938 with respect to the EUV exposure light. This allows the multilayer film 10 to reflect the EUV exposure light, thereby increasing the amount of EUV exposure light for the photoresist film 7.

[0091] The first material is any one of Si, SiC, B4C, BN, Ti, any oxide, or any nitride. The second material is any one of Rh, Ru, Mo, Nb, any oxide, or any nitride. This allows the multilayer film 10 to reflect the EUV exposure light, so the amount of EUV exposure light for the photoresist film 7 can be increased.

[0092] In addition, the substrate W has an SOG film 6 formed on its upper surface. In step a), a multilayer film 10 is formed on the SOG film 6. In step b), a photoresist film 7 is formed on the multilayer film 10. This allows light to be reflected by the multilayer film 10, so that the amount of light exposed to the photoresist film 7 can be increased.

[0093] Further, the substrate W has an SOC film 5 formed on its upper surface. In step a), a multilayer film 10 is formed on the SOC film 5. The method for manufacturing a semiconductor device in the above-described embodiment further includes step c) (e.g., step S14). In step c), an SOG film 6 is formed on the multilayer film 10 of the substrate W. In step b), a photoresist film 7 is formed on the SOG film 6. This allows light to be reflected by the multilayer film 10, thereby increasing the amount of light exposed to the photoresist film 7.

[0094] Moreover, the thickness of each pair of the first film and the second film alternately stacked in the multilayer film 10 is 6.0 to 8.0 nm, which makes it possible to increase the reflectance of the multilayer film 10.

[0095] Moreover, the thickness of each pair of the first and second films alternately stacked in the multilayer film 10 is set to have a high reflectance for light incident perpendicularly to the substrate W, and a decrease in reflectance as the angle of incidence from the perpendicular direction increases. This allows a large amount of light incident perpendicularly to be reflected, thereby realizing fine exposure of the photoresist film 7 in accordance with the mask.

[0096] The first material is Ti. The second material is Ru. The thickness of each pair of the first and second films alternately stacked in the multilayer film 10 is 7.0 to 7.6 nm. This allows a large amount of light incident from a vertical direction to be reflected, thereby achieving fine exposure of the photoresist film 7 in accordance with the mask.

[0097] In addition, in step a), a nitrided layer, an oxide layer, or a barrier layer made of a material with a low relative dielectric constant is formed between the first film and the second film, which can suppress roughness between the first film and the second film, thereby suppressing a decrease in the reflectance of the multilayer film 10.

[0098] Moreover, the manufacturing method of the semiconductor device in the above-mentioned embodiment further includes a step d) (e.g., step S15). In the step d), any one of a nitrided layer, an oxide layer, and a barrier layer made of a material with a low relative dielectric constant is formed on the SOG film 6 of the substrate W. In the step b), a photoresist film 7 is formed on any one of the nitrided layer, the oxide layer, and the barrier layer. This makes it possible to suppress roughness between the SOG film 6 and the photoresist film 7, thereby suppressing a decrease in reflectance.

[0099] In step b), the photoresist film 7 is formed to a thickness of 40 nm or less. In step c), the SOG film 6 is formed to a thickness of 40 nm or less. This makes it possible to suppress a decrease in reflectance.

[0100] In step b), a photoresist film 7 is formed to a thickness that increases the reflectance when the reflectance periodically increases and decreases due to the interference effect. In step c), an SOG film 6 is formed to a thickness that increases the reflectance when the reflectance periodically increases and decreases due to the interference effect. This makes it possible to suppress a decrease in reflectance. The SOG (Spin on Glass) film may be a SiO2 film, and may be SiO2 formed by CVD (Chemical Vapor Deposition) or ALD (Atomic Layer Deposition).

[0101] The first material is Si, and the second material is Ru, so that the multilayer film 10 has a high reflectance.

[0102] The first material is Si or Mo. The second material is Ru. The photoresist film 7 is a metal oxide resist. This allows the multilayer film 10 and the metal oxide resist mask to be etched with good selectivity by Cl2 gas.

[0103] [others] It should be noted that the technology disclosed in the present application is not limited to the above-described embodiment, and various modifications are possible within the scope of the gist thereof.

[0104] For example, in the above embodiment, EUV exposure has been described as an example, but the amount of light for exposure to a photoresist film can also be increased in the case of exposure using a KrF excimer laser or an ArF excimer laser.

[0105] It should be noted that the embodiments disclosed herein are illustrative in all respects and should not be construed as limiting. Indeed, the above-described embodiments may be embodied in various forms. Furthermore, the above-described embodiments may be omitted, substituted, or modified in various forms without departing from the scope and spirit of the appended claims.

[0106] In addition, the following supplementary notes are disclosed regarding the above embodiment.

[0107] (Appendix 1) a) forming a multilayer film on a substrate by alternately laminating a first film including a first material and a second film including a second material having a refractive index with respect to light used for exposure lower than that of the first material; b) depositing a photoresist film on the substrate over the multilayer film; A method for manufacturing a semiconductor device comprising the steps of:

[0108] (Appendix 2) The light used for exposure is light of a wavelength used for EUV (Extreme ultraviolet lithography) exposure, the first material has an extinction constant smaller than 0.035 and a refractive index larger than 0.945 with respect to the EUV exposure light, The second material has an extinction constant smaller than 0.035 and a refractive index smaller than 0.938 with respect to the EUV exposure light. 2. A method for manufacturing the semiconductor device according to claim 1.

[0109] (Appendix 3) The first material is any one of Si, SiC, B4C, BN, and Ti, any oxide thereof, or any nitride thereof; The second material is any one of Rh, Ru, Mo, and Nb, any oxide thereof, or any nitride thereof. 3. A method for manufacturing the semiconductor device according to claim 2.

[0110] (Appendix 4) The substrate has a SiO2 film formed on the upper surface thereof, Step a) comprises forming the multilayer film on the SiO2 film; Step b) is forming the photoresist film on the multilayer film. A method for manufacturing a semiconductor device according to any one of claims 1 to 3.

[0111] (Appendix 5) The substrate has a SOC (Spin On Carbon) film formed on the upper surface thereof, Step a) comprises forming the multilayer film on the SOC film; Step c) further comprises the step of forming a SiO2 film on the multilayer film of the substrate; Step b) comprises forming the photoresist film on the SiO2 film; Step c) is carried out after step a) and before step b). A method for manufacturing a semiconductor device according to any one of claims 1 to 3.

[0112] (Appendix 6) The thickness of each pair of the first film and the second film alternately stacked in the multilayer film is 6.0 to 8.0 nm. 4. A method for manufacturing a semiconductor device according to claim 2 or 3.

[0113] (Appendix 7) The thickness of each pair of the first film and the second film alternately stacked in the multilayer film is such that the reflectance of light incident on the substrate from a direction perpendicular to the substrate is high, and the reflectance decreases as the angle of incidence from the perpendicular direction increases. 7. A method for manufacturing a semiconductor device according to any one of claims 2, 3, and 6.

[0114] (Appendix 8) the first material is Ti; the second material is Ru; The thickness of each pair of the first film and the second film alternately stacked in the multilayer film is 7.0 to 7.6 nm. A method for manufacturing a semiconductor device according to any one of claims 2, 3, 6, and 7.

[0115] (Appendix 9) In step a), a nitrided layer, an oxide layer, or a barrier layer made of a material having a low relative dielectric constant is formed between the first film and the second film. A method for manufacturing a semiconductor device according to any one of claims 1 to 8.

[0116] (Appendix 10) d) forming any one of a nitrided layer, an oxide layer, and a barrier layer made of a material having a low dielectric constant on the SiO2 film of the substrate; Step b) is to deposit the photoresist film on the nitrided layer, the oxide layer, or the barrier layer. A method for manufacturing a semiconductor device according to any one of claims 1 to 9.

[0117] (Appendix 11) Step b) is to form the photoresist film having a thickness of 40 nm or less. 11. A method for manufacturing a semiconductor device according to any one of claims 1 to 10.

[0118] (Appendix 12) Step c) is to form the SiO2 film having a thickness of 40 nm or less. A method for manufacturing the semiconductor device according to claim 5.

[0119] (Appendix 13) In step b), the photoresist film is formed to a thickness such that the reflectance increases in response to the periodic increase and decrease in reflectance due to the interference effect. 13. A method for manufacturing a semiconductor device according to any one of claims 1 to 12.

[0120] (Appendix 14) In step c), the SiO2 film is formed to a thickness such that the reflectance increases in response to the periodic increase and decrease in reflectance due to the interference effect, and the film formation method is one of spin on, CVD, and ALD. 13. A method for manufacturing the semiconductor device according to claim 5 or 12.

[0121] (Appendix 15) the first material is Si; The second material is Ru. A method for manufacturing a semiconductor device according to any one of claims 2, 3, 6, 7, and 8.

[0122] (Appendix 16) the first material is Si or Mo; the second material is Ru; The photoresist film is a metal oxide resist. A method for manufacturing a semiconductor device according to any one of claims 2, 3, 6, 7, and 8.

[0123] (Appendix 17) a multilayer film in which a first film containing a first material and a second film containing a second material having a refractive index with respect to light used for exposure lower than that of the first material are alternately laminated; a photoresist film formed on the multilayer film; A substrate having [Explanation of symbols]

[0124] 1. Silicon substrate 2. Silicon thermal oxide film 3 Metal Hard Mask 7 Photoresist film 7A area 7b Resist pattern 10 Multilayer film W1~W11 Board

Claims

1. a) forming a multilayer film on a substrate by alternately stacking a first film containing a first material and a second film containing a second material having a refractive index with respect to light used for exposure lower than that of the first material; b) depositing a photoresist film on the substrate over the multilayer film; A method for manufacturing a semiconductor device comprising the steps of:

2. The light used for exposure is light having a wavelength used for EUV (Extreme ultraviolet lithography) exposure, the first material has an extinction constant smaller than 0.035 and a refractive index larger than 0.945 with respect to the EUV exposure light, The second material has an extinction constant smaller than 0.035 and a refractive index smaller than 0.938 with respect to the EUV exposure light. The method for manufacturing a semiconductor device according to claim 1 .

3. The first material is Si, SiC, B 4 Any of C, BN, and Ti, any of their oxides, or any of their nitrides; The second material is any one of Rh, Ru, Mo, and Nb, any oxide thereof, or any nitride thereof. The method for manufacturing a semiconductor device according to claim 2 .

4. The substrate has a SiO ２ The film is formed, In step a), the SiO ２ forming the multilayer film on the film; Step b) is forming the photoresist film on the multilayer film. The method for manufacturing a semiconductor device according to claim 1 .

5. The substrate has a spin on carbon (SOC) film formed on the upper surface thereof, Step a) comprises forming the multilayer film on the SOC film; Step c) forming a SiO ２ The method further includes the step of depositing a film, In step b), the SiO ２ forming the photoresist film on the film; Step c) is carried out after step a) and before step b). The method for manufacturing a semiconductor device according to claim 1 .

6. The thickness of each pair of the first film and the second film alternately stacked in the multilayer film is 6.0 to 8.0 nm. The method for manufacturing a semiconductor device according to claim 2 .

7. The thickness of each pair of the first film and the second film alternately stacked in the multilayer film is such that the reflectance of light incident on the substrate from a direction perpendicular to the substrate is high, and the reflectance decreases as the angle of incidence from the perpendicular direction increases. The method for manufacturing a semiconductor device according to claim 2 .

8. the first material is Ti; the second material is Ru; The thickness of each pair of the first film and the second film alternately stacked in the multilayer film is 7.0 to 7.6 nm. The method for manufacturing a semiconductor device according to claim 2 .

9. In step a), a nitrided layer, an oxide layer, or a barrier layer made of a material having a low relative dielectric constant is formed between the first film and the second film. The method for manufacturing a semiconductor device according to claim 1 .

10. d) The SiO of the substrate ２ The method further includes a step of forming, on the film, a nitrided layer, an oxide layer, or a barrier layer made of a material having a low dielectric constant; Step b) comprises depositing the photoresist film on either the nitrided layer, the oxide layer or the barrier layer. The method for manufacturing a semiconductor device according to claim 5 .

11. In step b), the photoresist film is formed to a thickness of 40 nm or less. The method for manufacturing a semiconductor device according to claim 1 .

12. Step c) is a step of forming a SiO ２ Depositing a film The method for manufacturing a semiconductor device according to claim 5 .

13. In step b), the photoresist film is formed to a thickness such that the reflectance increases in response to the periodic increase and decrease in reflectance due to the interference effect. The method for manufacturing a semiconductor device according to claim 1 .

14. Step c) is a step of forming a SiO film having a thickness at which the reflectance increases in the periodic increase and decrease in the reflectance due to the interference effect. ２ A film is formed by a method selected from the group consisting of spin on, CVD, and ALD. The method for manufacturing a semiconductor device according to claim 5 .

15. the first material is Si; The second material is Ru. The method for manufacturing a semiconductor device according to claim 2 .

16. the first material is Si or Mo; the second material is Ru; The photoresist film is a metal oxide resist. The method for manufacturing a semiconductor device according to claim 2 .

17. a multilayer film in which a first film containing a first material and a second film containing a second material having a refractive index with respect to light used for exposure lower than that of the first material are alternately laminated; a photoresist film formed on the multilayer film; A substrate having

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