Method for manufacturing semiconductor device, and substrate

Abstract

The purpose of the present invention is to provide: a method for manufacturing a semiconductor device that can increase the exposure amount of light on a photoresist film; and a substrate.　The method for manufacturing a semiconductor device comprises: a step (S13) for forming, on a substrate, a multilayer film 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 in exposure than that of the first material are alternately laminated; and a step (S15) for forming a photoresist film on top of the multilayer film.

Description

Semiconductor device manufacturing method and substrate

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

[0002] Patent Document 1 listed below discloses a technique for laminating a multilayer stack containing silicon and a non-metal on a substrate.

[0003] US Patent Application Publication No. 2021 / 116799

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

[0005] A method for manufacturing a semiconductor device according to one embodiment of the present disclosure includes steps a) and b). In step a), a multilayer film is formed on a substrate by alternately stacking first films containing a first material and second films containing a second material whose refractive index with respect to light used for exposure is lower than that of the first material. In step b), a photoresist film is formed on top of the multilayer film on the substrate.

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

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

[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 disclosed method for manufacturing a semiconductor device and the substrate 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 to light 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, miniaturization has also progressed in lithography technology. 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 investigated.

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

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

[0013] [Embodiment] An embodiment will be described. First, an example of conventional lithography will be outlined using FIG. 1A. FIG. 1A is a diagram illustrating an example of a conventional substrate W1. FIG. 1A shows the substrate W1. The substrate W1 includes a silicon substrate 1 on which 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 are sequentially stacked. 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 manufacturing a semiconductor device, films necessary for manufacturing the semiconductor device are formed on the silicon substrate 1 as needed.

[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. The photoresist film 7 may be, for example, CH ２ The photoresist film 7 has a thickness of, 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 substrate W1 is irradiated with light having a wavelength of 13.53 nm used in EUV exposure, most of the light does not contribute to the exposure of the photoresist film 7 and is absorbed by the substrate W1.

[0017] 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 the transmittance and reflectance of the substrate W1 shown in Fig. 1A. Fig. 1B shows changes in the absorption A and reflectance R of the substrate W1 relative to the incidence angle θ [deg] of light with a wavelength of 13.53 nm. As shown in Fig. 1B, the substrate W1 has very high absorption A and almost zero reflectance R at all incidence angles θ.

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

[0020] Candidates for the first and second materials constituting the multilayer film will now be described. Fig. 2 is a diagram illustrating candidate first and second materials constituting the multilayer film. In Fig. 2, each material is plotted according to its extinction coefficient k and refractive index n 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, which is used for EUV exposure, the first material preferably has an extinction constant k smaller than 0.035 and a refractive index n larger than 0.945. The first material is preferably, for example, a material surrounded by ellipse C1 in FIG. 2 . For example, the first material may be any of Si, SiC, B4C, BN, and Ti. Furthermore, even when Si, SiC, B4C, BN, and Ti are in the form of oxides or nitrides, their 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] Furthermore, the second material preferably has an extinction constant k smaller than 0.035 and a refractive index n smaller than 0.938. For example, the second material is preferably a material surrounded by ellipse C2 in FIG. 2 . For example, any of Rh, Ru, Mo, and Nb can be used as the second material. Furthermore, even when Rh, Ru, Mo, and Nb are converted into oxides or nitrides, their extinction constant k and refractive index n are approximately the same. Therefore, any of oxides or nitrides of Rh, Ru, Mo, and Nb can also 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 illustrating an example of a substrate W2 according to an embodiment. The substrate W2 is shown in FIG. 1A , but with a multilayer film 10 provided between the photoresist film 7 and the SOG film 6 of the substrate W1. The substrate W2 includes a silicon thermal oxide film 2, a metal hard mask 3, a SiO film 4, an SOC film 5, an SOG film 6, a multilayer film 10, and a photoresist film 7 stacked in this order on a silicon substrate 1. In FIG. 3A , the multilayer film 10 is formed by depositing 20 pairs of Si and Nb films, each pair consisting of one Si film and one Nb film.

[0025] For substrate W2, the transmittance and reflectance were calculated when the Si film thickness was 4 nm, the Nb film thickness was 3 nm, and the Si film and Nb film pair thickness was 7 nm. Figure 3B is a diagram showing an example of changes in the transmittance and reflectance of substrate W2 shown in Figure 3A. Figure 3B shows changes in absorption A and reflectance R for substrate W2 with respect to the angle of incidence 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, since the substrate W2 has the multilayer film 10 provided between the photoresist film 7 and the SOG film 6, the multilayer film 10 can reflect light, thereby increasing the amount of light exposed to the photoresist film 7.

[0028] 4A is a diagram illustrating an example of a substrate W3 according to an embodiment. The substrate W3 is shown in FIG. 1A , and illustrates a case in which a multilayer film 10 is provided between the SOG film 6 and the SOC film 5 of the substrate W1. The substrate W3 includes 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 stacked 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, with 20 pairs of films formed, each pair consisting of one Si film and one Nb film.

[0029] For substrate W3, the transmittance and reflectance were calculated when the Si film thickness was 4 nm, the Nb film thickness was 3 nm, and the pair of Si and Nb films had a total thickness of 7 nm. Figure 4B is a diagram showing an example of changes in the transmittance and reflectance of substrate W3 shown in Figure 4A. Figure 4B shows changes in absorption A and reflectance R for substrate W3 with respect to the angle of incidence 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 approximately 27% is obtained when the incident angle θ is approximately 0 to 10°.

[0031] In this way, since the substrate W3 has the multilayer film 10 provided between the SOG film 6 and the SOC film 5, the multilayer film 10 can reflect light, and therefore the amount of light 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 illustrating an example of a substrate W4 according to an embodiment. The substrate W4 is shown in FIG. 1A , where a multilayer film 10 is provided between the SOG film 6 and the SOC film 5 of the substrate W1. The substrate W4 includes 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 stacked 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, with 40 pairs of Si and Ru films being formed, each pair consisting of one Si film and one Ru film. Also, in FIG. 5A , the thickness of the SOG film 6 is, for example, 5 nm.

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

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

[0036] In this way, since the substrate W4 has the multilayer film 10 provided between the SOG film 6 and the SOC film 5, the multilayer film 10 can reflect light, and therefore the amount of light exposed to the photoresist film 7 can be increased.

[0037] 6A is a diagram illustrating an example of a substrate W5 according to an embodiment. The substrate W5 is shown in FIG. The number of pairs of the multilayer film 10 on the substrate W4 is 10.

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

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

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

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

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

[0043] In this way, the multilayer film 10 can reflect light even when the number of pairs is small, so that 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 stacked first film made of the first material and the second film made of the second material. Therefore, as long as the multilayer film 10 has at least one pair of first and second films stacked, the amount of light to be exposed to the photoresist film 7 can be increased. Even if the number of pairs in the multilayer film 10 is increased, the increase in reflectance saturates. Therefore, to obtain high reflectance while suppressing the film thickness of the multilayer film 10, the number of pairs in the multilayer film 10 is preferably 1 to 60, and more preferably 5 to 40. Furthermore, the multilayer film 10 may have a structure in which the first and second films are alternately stacked, and the number of layers of the first and second films does not need to be the same. For example, the multilayer film 10 may have a structure in which the first and second films are alternately stacked, with either the first or second film being the top or bottom surface of the stack.

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

[0046] FIG. 8A is a diagram illustrating an example of a substrate W7 according to an embodiment. The substrate W7 is shown in FIG. 1A , with a multilayer film 10 provided between the SOG film 6 and the SOC film 5 of the substrate W1. The substrate W7 includes 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 stacked 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, with 40 pairs of B4C and Ru films being formed, each pair consisting of one B4C film and one Ru film. Also, in FIG. 8A , the thickness of the SOG film 6 is, for example, 5 nm.

[0047] For substrate W7, the transmittance and reflectance were calculated when the Ru film thickness was 3.09 nm, the B4C film thickness was 4.11 nm, and the combined thickness of the Ru film and B4C film was 7.2 nm. Figure 8B shows an example of the changes in the transmittance and reflectance of substrate W7 shown in Figure 8A. Figure 8B shows the changes in the absorption A and reflectance R of substrate W7 with respect to the angle of incidence 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 approximately 35% is obtained when the incident angle θ is approximately 0 to 8°.

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

[0050] FIG. 9A is a diagram illustrating an example of a substrate W8 according to an embodiment. The substrate W8 is shown in FIG. 1A , in which a multilayer film 10 is provided between the SOG film 6 and the SOC film 5 of the substrate W1. The substrate W8 includes 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 stacked 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 BN and Ru films being formed, each pair consisting of one BN film and one Ru film. Also, in FIG. 9A , the thickness of the SOG film 6 is, for example, 5 nm.

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

[0052] As shown in Figure 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 approximately 30% is obtained when the incident angle θ is approximately 0 to 7 degrees.

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

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

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

[0056] FIG. 10A is a diagram illustrating an example of a substrate W9 according to an embodiment. The substrate W9 is shown in FIG. 10A . The substrate W9 illustrates a case in which 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 includes 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 stacked 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, with 20 pairs of films formed, each pair consisting of one Si film and one Mo film. Also, in FIG. 10A , the thickness of the SOG film 6 is, for example, 5 nm.

[0057] For substrate W9, the transmittance and reflectance were calculated by changing the thickness of one pair of Si and Mo films in the multilayer film 10. Figure 10B is a diagram showing an example of the change in reflectance depending on the thickness of one pair of Si and Mo films in the substrate W9 shown in Figure 10A. In Figure 10B, the vertical axis represents the thickness d of one pair of Si and Mo films in the multilayer film 10, and the vertical axis represents the angle of incidence θ [deg] of light with a wavelength of 13.53 nm. The reflectance corresponding to the angle of incidence θ is shown by the line at which the reflectance value is the same. Figure 10B also shows the reflectance value corresponding to the angle of incidence θ when the thickness of one pair is 7.0 to 7.3 nm. For example, when the thickness d of one pair is 7.0 nm, a reflectance of 43.3% (=0.433) or more is obtained when the angle of incidence θ is approximately 0 to 11°. Note that FIG. 10B omits cases where the film thickness of one pair is less than 7.0 nm or more than 7.3 nm, 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 graph 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, where Fig. 10C shows changes in absorption A and reflectance R with respect to the angle of incidence 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 changes in reflectance of the substrate W9 shown in Fig. 10A when the film thickness d is 7.1 nm, showing changes 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 changes in reflectance of the substrate W9 shown in Fig. 10A when the film thickness d is 7.15 nm, showing changes 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 Figure 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 degrees. On the other hand, as shown in Figure 10D, when the film thickness d is 7.1 nm, the reflectance increases when the incident angle θ is around 10 degrees compared to when the incident angle θ is 0 degrees. Furthermore, as shown in Figure 10E, when the film thickness d is 7.15 nm, the reflectance increases when the incident angle θ is around 10 to 12 degrees compared to when the incident angle θ is 0 degrees.

[0062] FIG. 11A is a diagram illustrating an example of a substrate W10 according to an embodiment. The substrate W10 is shown in FIG. 11A . The substrate W10 illustrates a case in which 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 includes 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 stacked 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, with 20 pairs of films formed, each pair consisting of one Ti film and one Ru film. Also, 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 in the multilayer film 10. Figure 11B is a diagram showing an example of the change in reflectance depending on the film thickness of one pair of Ti and Ru films in the substrate W10 shown in Figure 11A. In Figure 11B, the vertical axis represents the film thickness d of one pair of Ti and Ru films in the multilayer film 10, and the vertical axis represents the angle of incidence θ [deg] of light with a wavelength of 13.53 nm. The reflectance corresponding to the angle of incidence θ is shown by the line at which the reflectance value is the same. Figure 11B also shows the reflectance value corresponding to the angle of incidence 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 angle of incidence θ is approximately 0 to 12°.

[0064] In this way, the reflectance of the multilayer film 10 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 with respect to the angle of incidence θ also changes depending on the film thickness of the pair of films. By adjusting the film thickness of the pair of films in the multilayer film 10, it is possible to control which incident angle θ of light is reflected more and which is absorbed more. This allows for fine exposure.

[0065] For example, Figure 11A shows the incident 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 increasingly miniaturized, the numerical aperture (NA) of exposure tools has increased, and the incident angle θ of light relative to the substrate W10 has also widened. For example, in an EUV exposure tool manufactured by ASML in the Netherlands, the incident angle θ is 19.3° when the numerical aperture is 0.33, and 33.4° when the numerical aperture is 0.55. It is also planned to further increase the numerical aperture of EUV exposure tools; when the numerical aperture is 0.7, the incident angle θ is 44.4°.

[0066] 12A to 12C are diagrams illustrating an example of the flow of exposure of a substrate W10 according to an embodiment. FIG. 12A shows EUV light incident on the substrate W10. As the numerical aperture of the exposure apparatus increases, the angle of incidence θ also widens. Here, for example, the thickness of one pair of multilayer films 10 is adjusted so as to reflect more EUV light incident perpendicularly to the substrate W10 (incident angle θ = 0°). For example, the thickness of one pair is adjusted to a thickness that provides high reflectance for light incident perpendicularly to the substrate W10 and decreases as the angle of incidence from the perpendicular direction increases. For example, when primarily reflecting perpendicularly incident EUV light, the thickness of one pair is preferably 7.0 to 7.6 nm, and more preferably 7.1 to 7.4 nm.

[0067] FIG. 12B shows 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. Furthermore, diffusion of EUV light incident at a large angle of incidence θ can be suppressed. FIG. 12C shows a region 7A exposed by the incident and reflected EUV light. The photoresist film 7 is exposed to a large amount of EUV light in the region 7A that is hit by the EUV light incident from a perpendicular direction. This allows for fine exposure of the photoresist film 7 corresponding to the mask.

[0068] In the above-described embodiment, the transmittance and reflectance were 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 and second films stacked in the multilayer film 10. Therefore, an example will be described 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 and second films stacked in the multilayer film 10.

[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 Ru film thickness was 3.49 nm, the Ti film thickness 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] Furthermore, 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 Ru film thickness was 3.49 nm, the Ti film thickness 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. Furthermore, as shown in Fig. 13B, the reflectance R decreases as the roughness of the interface between the Ti film and the Ru film laminated 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 laminated 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 laminated on the multilayer film 10 is preferably 1 nm or less, and more preferably 0.5 nm or less. In order to suppress the roughness, a nitrided layer, an oxide layer, or a B film with a low relative dielectric constant is preferably formed on the interface between the multilayer film 10 and the SOG film 6 and the interface between the Ti film and the Ru film laminated on the multilayer film 10. ４ A barrier layer made of C or the like may be provided.

[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 layers. Therefore, an example will be described in which the transmittance and reflectance are calculated taking into account the interference effect between the multilayer film 10 and the upper layers.

[0073] For the substrate W10 shown in Figure 11A, the reflectance was calculated by changing the film thickness of the photoresist film 7. The reflectance was calculated under conditions where the Ru film thickness was 3.49 nm, the Ti film thickness was 3.86 nm, and light with a wavelength of 13.53 nm was incident at an incident angle θ = 10°. Figure 14A is a diagram showing an example of how the reflectance changes with the film thickness of the photoresist film 7 of the substrate W10 according to the embodiment. Figure 14A shows how the reflectance R changes with 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] Furthermore, for the substrate W10 shown in FIG. 11A , the reflectance was calculated by changing the thickness of the SOG film 6. The reflectance was calculated under the conditions that the Ru film thickness was 3.49 nm, the Ti film thickness 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 , as the thickness of the photoresist film 7 increases, the reflectance tends to decrease overall, while periodically increasing and decreasing due to the interference effect. Also, as shown in FIG. 14B , as the thickness of the SOG film 6 increases, the reflectance also tends to decrease overall, while periodically increasing and decreasing 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. Furthermore, the thicknesses of the photoresist film 7 and the SOG film 6 are preferably such that the reflectance increases with the periodic increase and decrease in 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 with the periodic increase and decrease in 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 part of the method for manufacturing a semiconductor device, a flow of forming each layer on a substrate will be described. Figure 15 is a flowchart 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, an 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. This results in the SOC film 5 being formed on the metal hard mask 3. Note that if an 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, a multilayer film 10 is formed on the silicon substrate 1 (step S13). For example, the multilayer film 10 is formed by alternately depositing a first film containing a first material and a second film containing a second material whose refractive index n with respect to the light used for exposure is lower than that of the first material by PVD deposition or atomic layer deposition (ALD). For example, when forming the Ru / Si multilayer film 10 by PVD deposition, the film is formed at a pressure of approximately 0.1 to 10 Pa using a process gas such as Ar. The film formation time, input power, etc. are adjusted to achieve the designed film thickness. Adding nitrogen or oxygen during film formation and performing reactive sputtering can also be effective. For example, slight nitridation of the upper Si layer may potentially control interlayer diffusion. Furthermore, when forming the Ru / Si multilayer film 10 by ALD, appropriate precursors for Ru / Si film formation are selected. Furthermore, the number of ALD cycles for each of Ru and Si is adjusted so that the Ru / Si film thickness 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, a material with a low relative dielectric constant (for example, B ４ C) may be deposited.

[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. This results in the SOG film 6 being formed on the multilayer film 10. To suppress a decrease in reflectance, the thickness of the SOG film 6 is preferably 40 nm or less. Furthermore, in step S14, it is preferable to form the SOG film 6 with a thickness that increases the reflectance when the reflectance periodically increases and decreases 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 step S15, the photoresist film 7 is preferably formed to a thickness that increases the reflectance in the periodic increase and decrease in reflectance due to the interference effect. In step S15, in order to suppress roughness at the interface between the SOG film 6 and the photoresist film 7, a nitrided layer, an oxide layer, a material with a low relative dielectric constant (for example, B ４ C) may be deposited.

[0082] In the case where 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, a substrate patterning process, including a lithography process, will be described as part of a semiconductor device manufacturing method. FIG. 16 is a diagram illustrating an example of a patterning process included in a semiconductor device manufacturing method according to an embodiment. In FIG. 16, (A) to (I) show a process for patterning a substrate W11. As shown in FIG. 16(A), the substrate W11 includes a silicon substrate 1 on which 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 are stacked in this order. Since the SiO film 4 is etched during etching of the SOC film 5, 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 by depositing multiple pairs of films, each pair consisting of one Si film and one Ru film, with Si as the first material and Ru as the second material. The substrate W11 may also include a SiN film or SiC film stacked instead of the SOG film 6. Furthermore, when the adhesion of the photoresist film 7 to the substrate W11 is an issue, the SOG film 6 may be a combination of an SiO film and an SiC film, an SiO film and an SiN film, or an SiC film and an SiN film.

[0084] In the manufacture of a semiconductor device, the substrate W11 is exposed by EUV exposure. As a result, a region 7A of the photoresist film 7 on the substrate W11 is exposed to incident and reflected EUV light, as shown in FIG. 16(B). After 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 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, for example, with 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 is etched using, for example, Cl gas, O ２ 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, using the multilayer film 10 as a mask, the SOC film 5 is etched as shown in FIG. 16(F). Then, the multilayer film 10 is removed, and using the SOC film 5 as a mask, the metal hard mask 3 is etched as shown in FIG. 16(G). The multilayer film 10 may be removed together with the etching gas for the metal hard mask 3. Alternatively, for example, Cl gas or O gas may be used as the metal hard mask 3. ２ When a metal hard mask such as IGZO, which is resistant to gases, is used, after completing the patterning of the metal hard mask 3, the multilayer film 10 may be etched to remove the multilayer film 10. 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 also be a TEOS (CVD SiO2), SiN, or low-k film.

[0087] In order to obtain a high reflectance in the multilayer film 10, it is preferable that the refractive indexes n of the first and second materials alternately stacked 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 by alternately stacking Si films and Ru films. Furthermore, in consideration of processing, it is preferable that the multilayer film 10 be configured such that the first material is Si and the second material is Mo, and Si films and Mo films are alternately stacked. The multilayer film 10 configured such that Si films and Mo films are alternately stacked is preferable to obtain a high reflectance in the multilayer film 10. ２ The gas allows etching with a good selectivity to the SOG film 6 mask.

[0088] Furthermore, 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 a metal oxide resist is used, the multilayer film 10 is preferably configured such that the first material is Si or Mo and the second material is Ru, with Si or Mo films and Ru films alternately stacked. The multilayer film 10 configured such that Si or Mo films and Ru films alternately stacked is preferably Cl. ２ The gas allows etching with good selectivity to the metal oxide resist mask, and 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 (a collective term for substrates W2 to W11) by alternately stacking first films containing a first material and second films containing a second material whose refractive index n with respect to light used for exposure is lower than that of the first material. In step b), a photoresist film 7 is formed on top of the multilayer film 10 on the substrate W. This allows light to be reflected by the multilayer film 10, thereby increasing the amount of light exposure to the photoresist film 7.

[0090] The light used for exposure is light of a wavelength used for EUV exposure. The first material has an extinction constant k of less than 0.035 and a refractive index of more than 0.945 for the EUV exposure light. The second material has an extinction constant k of less than 0.035 and a refractive index of less than 0.938 for 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, and Ti, or any oxide or nitride thereof. The second material is any one of Rh, Ru, Mo, and Nb, or any oxide or nitride thereof. This allows the multilayer film 10 to reflect EUV exposure light, thereby increasing the amount of EUV exposure light applied to the photoresist film 7.

[0092] The substrate W also 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, thereby increasing the amount of light exposed to the photoresist film 7.

[0093] The substrate W also 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] The thickness of each pair of the first and second films alternately stacked in the multilayer film 10 is 6.0 to 8.0 nm, which allows the reflectance of the multilayer film 10 to be increased.

[0095] Furthermore, the thickness of each pair of the first and second films alternately stacked in the multilayer film 10 is set so that the reflectance of light incident from a direction perpendicular to the substrate W is high, and the reflectance decreases as the angle of incidence from the perpendicular direction increases. This allows a large amount of light incident from a direction perpendicular to the substrate W to be reflected, thereby achieving fine exposure of the photoresist film 7 corresponding to the mask.

[0096] The first material is Ti. The second material is Ru. The film 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 perpendicular 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 dielectric constant is formed between the first and second films, which can suppress roughness between the first and second films and therefore suppress a decrease in the reflectance of the multilayer film 10.

[0098] Moreover, the method for manufacturing a semiconductor device in the above-described embodiment further includes step d) (e.g., step S15). In step d), any one of a nitrided layer, an oxide layer, and a barrier layer made of a material with a low dielectric constant is formed on the SOG film 6 of the substrate W. In 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 in response to the periodic increase and decrease in reflectance due to the interference effect. In step c), an SOG film 6 is formed to a thickness that increases the reflectance in response to the periodic increase and decrease in reflectance due to the interference effect. This makes it possible to suppress a decrease in reflectance. The SOG (Spin on Glass) film is made of SiO ２ Any film is acceptable, and SiO film formed by CVD (Chemical Vapor Deposition) or ALD (Atomic Layer Deposition) is also acceptable. ２ That's fine.

[0101] The first material is Si, and the second material is Ru, which allows the multilayer film 10 to have 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. ２ The gas allows etching of the multilayer film 10 and the metal oxide resist mask with good selectivity.

[0103] [Others] 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 the photoresist film can also be increased in exposure using a KrF excimer laser or an ArF excimer laser.

[0105] It should be noted that the disclosed embodiments are illustrative in all respects and should not be considered 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-described embodiment.

[0107] (Supplementary Note 1) A method for manufacturing a semiconductor device, comprising: a) forming a multilayer film on a substrate, the multilayer film being formed by alternately stacking first films containing a first material and second films containing a second material, the second material having a refractive index to light used for exposure lower than that of the first material; and b) forming a photoresist film on top of the multilayer film on the substrate.

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

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

[0110] (Note 4) The substrate has a SiO ２ A film is formed, and in step a), the SiO ２and forming the multilayer film on a film; and in step b), forming the photoresist film on the multilayer film.

[0111] (Note 5) The substrate has an SOC (Spin On Carbon) film formed on the upper surface thereof, and in step a), the multilayer film is formed on the SOC film, and in step c), SiO ２ The method further includes a step of forming a film, and the step b) is ２ forming the photoresist film on the film; and step c) being performed after step a) and before step b).

[0112] (Supplementary Note 6) The method for manufacturing a semiconductor device according to Supplementary Note 2 or 3, wherein the film 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.

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

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

[0115] (Appendix 9) The method for manufacturing a semiconductor device according to any one of Appendices 1 to 8, wherein step a) forms any one of a nitrided layer, an oxide layer, and a barrier layer made of a material having a low dielectric constant between the first film and the second film.

[0116] (Supplementary Note 10) d) The SiO of the substrate ２The method for manufacturing a semiconductor device according to any one of appendices 1 to 9, further comprising the step of forming, on the film, any one of a nitrided layer, an oxide layer, and a barrier layer made of a material having a low dielectric constant, and in step b), forming the photoresist film on any one of the nitrided layer, the oxide layer, and the barrier layer.

[0117] (Appendix 11) The method for manufacturing a semiconductor device according to any one of Appendices 1 to 10, wherein in step b), the photoresist film is formed to a thickness of 40 nm or less.

[0118] (Appendix 12) In step c), the SiO ２ The method for manufacturing a semiconductor device according to claim 5, further comprising forming a film.

[0119] (Supplementary Note 13) The method for manufacturing a semiconductor device according to any one of Supplementary Notes 1 to 12, wherein step b) comprises depositing the photoresist film to a thickness that increases reflectance in a periodic increase and decrease in reflectance due to an interference effect.

[0120] (Supplementary Note 14) In step c), the SiO 2 film is formed to a thickness that increases the reflectance in the periodic increase and decrease of the reflectance due to the interference effect. ２ 13. The method for manufacturing a semiconductor device according to claim 5 or 12, wherein a film is formed by a method selected from the group consisting of spin-on, CVD, and ALD.

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

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

[0123] (Supplementary Note 17) A substrate having a multilayer film formed by alternately stacking a first film containing a first material and a second film containing a second material having a refractive index to light used for exposure lower than that of the first material, and a photoresist film formed on the top of the multilayer film.

[0124] REFERENCE SIGNS LIST 1 silicon substrate 2 silicon thermal oxide film 3 metal hard mask 7 photoresist film 7A region 7b resist pattern 10 multilayer film W1 to W11 substrate

Claims

1. A method for manufacturing a semiconductor device, comprising: 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, the second material having a lower refractive index to light used for exposure than the first material; and b) forming a photoresist film on top of the multilayer film on the substrate.

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

3. The method for manufacturing a semiconductor device according to claim 2, wherein the first material is any one of Si, SiC, B4C, BN, Ti, any oxide thereof, or any nitride thereof, and the second material is any one of Rh, Ru, Mo, Nb, any oxide thereof, or any nitride thereof.

4. The substrate has a SiO ２ A film is formed, and in step a), the SiO ２ 2. The method for manufacturing a semiconductor device according to claim 1, further comprising the steps of: forming the multilayer film on a film; and forming the photoresist film on the multilayer film in step b).

5. The substrate has an SOC (Spin on Carbon) film formed on the upper surface thereof, and in step a) the multilayer film is formed on the SOC film, and in step c) a SiO ２ The method further includes a step of forming a film, and the step b) is ２ The method for manufacturing a semiconductor device according to claim 1 , further comprising the steps of: forming the photoresist film on a film; and performing step c) after step a) and before step b).

6. The method for manufacturing a semiconductor device according to claim 2, wherein 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.

7. The method for manufacturing a semiconductor device described in claim 2, wherein 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 perpendicularly to the substrate is high and the reflectance decreases as the angle of incidence from the perpendicular direction increases.

8. The method for manufacturing a semiconductor device according to claim 2, wherein the first material is Ti, the second material is Ru, and 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.

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

10. d) The SiO of the substrate ２ 6. The method for manufacturing a semiconductor device according to claim 5, further comprising the step of forming, on the film, any one of a nitrided layer, an oxide layer, and a barrier layer made of a material having a low relative dielectric constant, and in step b), forming the photoresist film on any one of the nitrided layer, the oxide layer, and the barrier layer.

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

12. In step c), the SiO ２ The method for manufacturing a semiconductor device according to claim 5, further comprising forming a film.

13. The method for manufacturing a semiconductor device according to claim 1, wherein step b) comprises depositing the photoresist film to a thickness that increases the reflectance in the periodic increase and decrease in reflectance caused by an interference effect.

14. In step c), the SiO film is formed to a thickness at which the reflectance increases in the periodic increase and decrease in reflectance due to the interference effect. ２ 6. The method for manufacturing a semiconductor device according to claim 5, further comprising forming a film by a method selected from the group consisting of spin on, CVD, and ALD.

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

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

17. A substrate having a multilayer film formed by alternately stacking a first film containing a first material and a second film containing a second material having a refractive index for exposure light lower than that of the first material, and a photoresist film formed on the top of the multilayer film.

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