Photomask and Exposure Method

Abstract

The purpose of this invention is to suppress dimensional conversion differences generated during exposure. An embodiment of the photomask includes a splicing region having a first end at one end and a second end at a predetermined distance inward from the first end, and comprises: a substrate; a reflective layer disposed on a first surface of the substrate to reflect light; and a light-shielding pattern disposed on a second surface of the reflective layer opposite to the substrate, comprising a light-absorbing layer for absorbing light; and configured such that, in the splicing region, the light reflection intensity is lower on the first end side than on the second end side.

Description

Technical Field

[0001] The present invention relates to a photomask and an exposure method. Prior Technology

[0002] In high-numerical aperture extreme ultraviolet (High-NA EUV) exposure, the masking magnification is, for example, 4×8 times relative to the pattern transferred onto the wafer. On the other hand, the photomask itself maintains a size based on, for example, a masking magnification of 4×4 times. [Previous Technical Documents] [Non-patent literature]

[0003] [Non-Patent Literature 1] Vincent Wiauxa et al., “An experimental stitching study on the eve of High NA EUV”, Advanced Lithography, April 10, 2024, Engineering, Physics Summary of the Invention

[0004] [The problem the invention aims to solve] One embodiment aims to provide a photomask and exposure method that can suppress size conversion differences caused by exposure. [Technical means to solve the problem]

[0005] The photomask of the embodiment includes a splicing area having a first end at one end and a second end at a position extending inward from the first end at a predetermined distance, and comprises: a substrate; a reflective layer disposed on a first surface of the substrate to reflect light; and a light-shielding pattern disposed on a second surface of the reflective layer opposite to the substrate, including a light-absorbing layer that absorbs the light; and configured such that, in the splicing area, the light reflection intensity is lower on the first end side than on the second end side. Simple Explanation of the Diagram

[0006] Figures 1A-1C are schematic diagrams showing an example of the composition of the photomask in Embodiment 1. Figures 2A to 2G are schematic diagrams showing an example of the configuration of a light-shielding pattern prepared on the opposite side of the wafer in Embodiment 1. Figures 3A and 3B are cross-sectional views illustrating a portion of the sequence of exposure methods using the photomask of Embodiment 1. Figures 4A and 4B are cross-sectional views illustrating a portion of the sequence of exposure methods using the photomask of Embodiment 1. Figures 5A-5D are cross-sectional views illustrating part of the sequence of wafer processing methods in Embodiment 1. Figures 6A-6D are schematic diagrams showing an example of the composition of a light-shielding pattern prepared on the opposite side of the wafer in Embodiment 1, Variation 1. Figures 7A-7C are schematic diagrams showing one example of the composition of the photomask in variation 2 of embodiment 1. Figures 8A and 8B are schematic diagrams showing an example of the structure of the photomask in Embodiment 2. Figures 9A to 9E are cross-sectional views illustrating a portion of the manufacturing method of the protective film in Embodiment 2. Figures 10A to 10F are cross-sectional views illustrating a portion of the manufacturing method of the protective film in Embodiment 2. Figures 11A and 11B are cross-sectional views illustrating part of the manufacturing method of the protective film of Variation 1 of Embodiment 2. Figure 12 is a cross-sectional view illustrating part of the manufacturing method of the protective film of variation 1 of embodiment 2. Figures 13A-13C are cross-sectional views illustrating part of the manufacturing method of the protective film of variation 1 of embodiment 2. Figures 14A and 14B are cross-sectional views illustrating part of the manufacturing method of the protective film of Variation 1 of Embodiment 2. Figure 15 is a cross-sectional view illustrating part of the manufacturing method of the protective film of variation 1 of embodiment 2. Figures 16A-16C are cross-sectional views illustrating a portion of the manufacturing method of the protective film in Example 2 of Embodiment 2. Figures 17A to 17C are cross-sectional views illustrating part of the manufacturing method of the protective film in variation 3 of embodiment 2. Figures 18A to 18C are cross-sectional views illustrating part of the manufacturing method of the protective film in variation 3 of embodiment 2. Figures 19A and 19B are cross-sectional views illustrating part of the manufacturing method of the protective film in variation 3 of embodiment 2. Figures 20A and 20B are schematic diagrams showing the configuration of the photomask in Example 4 of Embodiment 2. Implementation

[0007] Hereinafter, embodiments of the present invention will be described in detail with reference to drawings. However, the present invention is not limited to the embodiments described below. Furthermore, the constituent elements in the embodiments described below include those readily conceived by those skilled in the art or substantially the same.

[0008] [Implementation Form 1] Hereinafter, embodiment 1 will be described in detail with reference to the drawings.

[0009] (Example of photomask construction) Figures 1A and 1C are schematic diagrams showing an example of the configuration of the photomask 10 in Embodiment 1. More specifically, Figure 1A is a cross-sectional view of the photomask 10 with the protective film 20 installed, and Figures 1B and 1C are schematic diagrams showing the general outline of the exposure method using the photomask 10.

[0010] Furthermore, in the following cases, even if it is only described as photomask 10, unless otherwise specified, it refers to photomask 10 with the protective film 20 described in detail below installed.

[0011] The photomask 10 in Embodiment 1 is configured, for example, as a reflective photomask for high NA-EUV exposure.

[0012] High-NA-EUV exposure is a technique that uses lenses with a numerical aperture (NA) increased from the current 0.33 to 0.55 to expose to extreme ultraviolet (EUV) light at 13.5 nm. NA is a physical quantity that indicates the performance of a lens that can converge and focus light. By using lenses with high NA, finer patterns can be formed.

[0013] Furthermore, in high-NA-EUV exposure, the mask magnification, which is currently 4×4 times, becomes 4×8 times compared to the pattern transferred onto the wafer. Therefore, in order to maintain the current mask size, for example, two photomasks 10 (10-1, 10-2) are used to expose one irradiation area on the wafer. Figures 1B and 1C illustrate this situation.

[0014] As shown in Figure 1B, one of the paired photomasks 10 (10-1, 10-2), photomask 10-1, is used to expose approximately half of the irradiation area SH on the wafer.

[0015] As described above, the photomask 10 in Embodiment 1 is, for example, a reflective photomask, which reflects the EUV light L1 emitted from the light source LS onto the irradiated area SH. Although omitted in the figure, the light L1 and L2 each reach the irradiated area SH on the photomask 10 or wafer, which is the target, via a plurality of mirrors.

[0016] As shown in Figure 1C, the remaining approximately half of the irradiation area SH on the wafer is exposed using another photomask 10-2 of the pair of photomasks 10 (10-1, 10-2).

[0017] Here, a portion of the exposure area EX1 of photomask 10-1 and a portion of the exposure area EX2 of photomask 10-2 overlap near the center of the illumination area SH. Therefore, since this overlapping exposure area Dex is a double exposure, it is preferable to make some adjustments to prevent excessive light exposure caused by the double exposure. This is because when excessive light occurs, there is a risk of increased dimensional conversion differences in the exposure area Dex, such as a thinning of the transfer pattern on the wafer.

[0018] Therefore, a splicing area ST corresponding to the exposure area Dex is set in the photomask 10, and the amount of light in the exposure area Dex is adjusted accordingly.

[0019] More specifically, in photomask 10-1, at the positions corresponding to the center of the irradiation area SH on the left and right sides of the paper, namely, the right side end E12-1 of the paper, a splicing area ST is provided. In photomask 10-2, at the positions corresponding to the center of the irradiation area SH on the left and right sides of the paper, namely, the left side end E12-2 of the paper, a splicing area ST is provided.

[0020] In the splicing area ST, the transfer patterns of the exposure areas EX1 and EX2 spanning the two photomasks 10 are joined together in a manner that matches each other in the irradiation area SH.

[0021] As shown in Figure 1A, the basic structure of the photomasks 10 used in pairs can be shared with each other.

[0022] The photomask 10 includes a glass substrate 12 with one side covered by a conductive layer 11, and the other side of the glass substrate 12 faces the wafer side. The conductive layer 11 is held on the electrostatic chuck 30 or the like of the exposure apparatus. The glass substrate 12 is made of, for example, low thermal expansion glass.

[0023] Furthermore, the photomask 10 on the side of the glass substrate 12 facing the wafer has a reflective layer 13, a buffer layer 14, and a light-absorbing layer 15 sequentially arranged from the side of the glass substrate 12.

[0024] The reflective layer 13, for example, has a multilayer structure in which a plurality of Mo layers and a plurality of Si layers are stacked alternately. In this way, light such as exposure light incident on the reflective layer 13 at a predetermined angle undergoes diffraction and is reflected at an angle corresponding to the incident angle. Since extremely short wavelength light such as EUV is difficult to reflect by optical mirrors, this artificial lattice structure is used to achieve reflection.

[0025] The buffer layer 14, for example, is a Ru layer, and serves as the base layer for the light-absorbing layer 15. The light-absorbing layer 15, for example, is a TaBN layer, and has the property of absorbing exposure light such as EUV. Furthermore, the light-absorbing layer 15 and the buffer layer 14 together form a light-shielding pattern P1 with a predetermined pattern, which is dispersed on the reflective layer 13.

[0026] The light-absorbing layer 15 of the light-shielding pattern P1 absorbs the light L1 from the light source LS. On the other hand, the remaining light L2 is reflected to the wafer side by the reflective layer 13 exposed from the light-shielding pattern P1, thereby transferring the light-shielding pattern P1 to the irradiated area SH of the wafer.

[0027] Additionally, as described later, the photomask 10 has a light-shielding pattern in the splicing area ST that is not transferred to the wafer.

[0028] The protective film 20 may have a protective layer 21 and a frame 22, and a surface with a protective light shield pattern P1, etc.

[0029] The protective layer 21 can be, for example, a carbon-based layer such as carbon nanotubes or graphene, a resin layer such as polyimide, or an inorganic layer such as polycrystalline silicon or silicon carbide. When the protective layer 21 is a carbon-based layer, it is preferably made of a material with a carbon content of 40% or more by weight. In this way, the protective layer 21 has high transmittance to EUV and other exposure light, and hardly hinders the incident light L1 from the light source LS onto the photomask 10, and the exit light L2 reflected in the photomask 10, thus covering and protecting the surface of the photomask 10.

[0030] The frame 22 is made of, for example, aluminum alloy and supports the protective layer 21. In the example of FIG1A, the frame 22 and the photomask 10 are held together by the electrostatic chuck 30 of the exposure apparatus, but the lower end of the frame 22 can be directly held on the surface of the photomask 10 by means of an adhesive or the like.

[0031] Alternatively, the protective film 20 may have an oxidation suppression layer (not shown) on the side of the protective layer 21 facing the wafer to suppress oxidation of the protective layer 21. In this case, an oxidation suppression layer, such as a SiO2 layer or a SiN layer, may be used as the oxidation suppression layer.

[0032] Alternatively, the protective layer 21 not installed on the frame 22 can be used alone, or the protective layer 21 with an oxidation inhibition layer can be used as a protective film.

[0033] The photomask 10 with the above-mentioned structure can be manufactured, for example, as follows.

[0034] On the glass substrate 12, a reflective layer 13 is formed by alternately depositing Mo and Si layers layer by layer using chemical vapor deposition (CVD) or sputtering. Furthermore, a buffer layer 14 and a light-absorbing layer 15 are sequentially formed on the reflective layer 13 using CVD or sputtering, and then processed into a pattern shape including a light-shielding pattern P1 using reactive ion etching (RIE). Additionally, a conductive layer 11 is formed on the back side of the glass substrate 12 using CVD or sputtering.

[0035] Based on the above, the photomask 10 of embodiment 1 is manufactured.

[0036] Furthermore, the protective film 20 having the above-described structure can be manufactured, for example, as follows.

[0037] CVD is used to form a protective layer 21 on the support substrate. When the protective layer 21 is a resin layer, it can also be formed by immersing the support substrate in a dispersion of resin containing the material that forms the protective layer 21. Furthermore, an oxidation inhibition layer covering the protective layer 21 can be further formed by CVD or the like. Afterward, the protective layer 21 is attached to the frame 22.

[0038] Based on the above, the protective film 20 of embodiment 1 is manufactured.

[0039] Figures 2A to 2G are schematic diagrams showing an example of the configuration of the light-shielding patterns P1 and P2 prepared on the face opposite to the wafer in Embodiment 1. More specifically, Figure 2A is a top view showing an example of the configuration of the light-shielding patterns P1 and P2, and Figures 2B to 2G are top views showing several examples of the configuration of the light-shielding pattern P2.

[0040] As shown in Figure 2A, the light-shielding pattern P1 is set over approximately the entire area of ​​the photomask 10, which includes the splicing area ST, facing the wafer. As described above, the light-shielding pattern P1 is a pattern transferred to the wafer, and can be any pattern based on the design pattern, selected from various patterns such as line and gap patterns, dot patterns, and hole patterns.

[0041] Like light-shielding pattern P1, light-shielding pattern P2 is a pattern composed of light-absorbing layer 15 and buffer layer 14 disposed on reflective layer 13. However, while light-shielding pattern P1 is transferred to the wafer through combination with reflective layer 13, light-shielding pattern P2 is not transferred to the wafer as described above. Light-shielding pattern P2 can be, for example, an SRAF (Sub-Resolution Assist Feature) pattern.

[0042] More specifically, the light-blocking pattern P2 is disposed in the splicing area ST, and is configured such that the coverage rate increases in stages from one end of the splicing area ST, namely end E31, toward the other end of the splicing area ST, namely end E32.

[0043] Here, the end E31 of the splicing area ST is the end closest to the center of the photomask 10. Also, the end E32 of the splicing area ST is located at the end E12 on one side of the photomask 10. That is, the end E32 of the splicing area ST coincides with the end E12 on one side of the photomask 10.

[0044] Figures 2B to 2G show several examples of shading patterns P2 with such varying coverage.

[0045] In the examples shown in Figures 2B to 2D, the light-blocking patterns P21a to P21c, which are light-blocking patterns P2, all have line and gap patterns.

[0046] As shown in Figure 2B, the light-blocking pattern P21a is composed of lines with constant widths and gaps that gradually decrease in width towards the ends E32 of the splicing area ST.

[0047] As shown in Figure 2C, the light-blocking pattern P21b is composed of lines whose width gradually increases toward the end E32 of the splicing area ST, and gaps of constant width.

[0048] As shown in Figure 2D, the light-blocking pattern P21c is composed of a line whose width gradually increases toward the end E32 of the splicing area ST, and a gap whose width gradually decreases.

[0049] In the examples shown in Figures 2E to 2G, the light-blocking patterns P22a to P22c, which are light-blocking patterns P2, all have dot patterns.

[0050] As shown in Figure 2E, the light-blocking pattern P22a has points with a constant area, which are arranged such that the spacing decreases toward the end E32 of the splicing area ST.

[0051] As shown in Figure 2F, the light-blocking pattern P22b has a plurality of points of different areas, which are arranged such that the area increases toward the end E32 of the splicing area ST.

[0052] As shown in Figure 2G, the light-blocking pattern P22c has a plurality of points of different areas, which are arranged such that the area increases and the spacing decreases towards the end E32 of the splicing area ST.

[0053] Thus, for example, a light-shielding pattern P2 can be formed by combining lines with gap patterns, dot patterns, and other prescribed patterns. By changing any one or both of the density (spacing) and size (width, area) of these patterns, the light-shielding pattern P2 can be formed in a way that the coverage rate increases in stages from the end E31 to the end E32 of the splicing area ST.

[0054] Within the splicing area ST, a light-shielding pattern P2 is formed in such a way that the amount of light reflected from the photomask 10 to the wafer per unit area is weaker as it approaches the end E12 on one side of the photomask 10. Therefore, excessive light caused by double exposure can be suppressed in the overlapping portion of the exposure areas EX1 and EX2 of the paired two photomasks 10 (refer to Figures 1B and 1C), i.e., in the exposure area Dex.

[0055] With this configuration, the splicing area ST of the photomask 10 in embodiment 1 has the function of adjusting the light-blocking pattern P1 and the like transferred to the exposure areas EX1 and EX2 to match each other in the irradiation area SH.

[0056] Furthermore, in the above example, the case where the light-shielding pattern P2 has a line and gap pattern or a dot pattern has been described, but the light-shielding pattern P2 is not limited to these patterns. As long as the reflection intensity in the photomask 10 per unit area can be adjusted, any pattern such as a combination of line and gap patterns and dot patterns, or other patterns, can be used.

[0057] Furthermore, the basic configuration of the paired photomasks 10 (10-1, 10-2) is common, for example, as described above. However, this does not mean that the paired photomasks 10 each have the same light-shielding pattern P1 and the same light-shielding pattern P2.

[0058] Regarding the light-shielding pattern P1, each photomask 10 can have different light-shielding patterns P1 depending on the position of the corresponding irradiation area SH of the wafer (refer to Figures 1B and 1C). For example, one of a pair of photomasks 10 may have a light-shielding pattern P1 corresponding to a component pattern, while the other has a light-shielding pattern P1 corresponding to a peripheral circuit pattern. On the other hand, when a repeating pattern, such as a cell array of large capacitors, occupies most of the irradiation area SH, the pair of photomasks 10 may have equal light-shielding patterns P1.

[0059] Furthermore, regarding the light-shielding pattern P2, the paired photomasks 10 can each adopt a light-shielding pattern P2 of any shape and configuration, and each photomask 10 can be configured to have light-shielding patterns P2 that are equal to each other, or it can be configured to have light-shielding patterns P2 that are different from each other.

[0060] (Pattern Formation Method) Next, using Figures 3A to 5D, a pattern forming method including the exposure method using the photomask 10 of Embodiment 1 will be described.

[0061] Figures 3A to 4B are cross-sectional views illustrating a portion of the exposure method using the photomask 10 of Embodiment 1.

[0062] As shown in Figure 3A, a wafer 100 is prepared to be sequentially formed with a processing layer 110 and a photoresist layer 120.

[0063] The wafer 100 is, for example, a silicon wafer or other semiconductor substrate. The processed layer 110 is a layer that is processed into a shape such as a light-shielding pattern P1, and may be an insulating layer such as a SiO2 layer or a SiN layer, a semiconductor layer such as a polycrystalline silicon layer, or a metal layer such as a tungsten layer. In the examples of Figures 3A to 5D, the processed layer 110 is an insulating layer such as a SiO2 layer. The photoresist layer 120 becomes the exposure target using the photomask 10, and serves as a mask layer when processing the processed layer 110.

[0064] Additionally, wafer 100 is divided into multiple irradiation regions SH.

[0065] As shown in Figure 3B, one of the paired photomasks 10 (e.g., photomask 10-1) is mounted on the electrostatic chuck 30 of the exposure apparatus and positioned at a predetermined position opposite to the wafer 100 being transported into the exposure apparatus. EUV light L1 is irradiated onto the photomask 10 from the light source LS of the exposure apparatus (refer to Figures 1B and 1C), causing it to reflect. The reflected light L2 then irradiates the photoresist layer 120 of a predetermined irradiation area SH among a plurality of irradiation areas SH on the wafer 100.

[0066] As described above, in high NA-EUV exposure, the masking ratio is, for example, 4×8. By combining pairs of photomasks 10, the entire irradiation area SH corresponding to the 4×8 masking ratio is exposed. Therefore, by the processing shown in FIG. 3B, the photoresist layer 120 is exposed in approximately half of the irradiation area SH. As described above, the area exposed by one photomask 10 is referred to as the exposure area EX1.

[0067] In the exposure area EX1, a pattern with a shape similar to the light-shielding pattern P1 of a photomask 10 is transferred into the photoresist layer 120. However, in the area (exposure area Dex) corresponding to the splicing area ST of the photomask 10 within the exposure area EX1, the photoresist layer 120 is exposed to attenuated exposure light (light L2), so the photosensitivity of the photoresist layer 120 is lower than that of other parts of the exposure area EX1.

[0068] As shown in Figure 4A, one of the paired photomasks 10 (e.g., photomask 10-2) is mounted on the electrostatic chuck 30 of the exposure apparatus and positioned at a predetermined position opposite to the wafer 100 within the exposure apparatus. EUV light L1 is irradiated onto the photomask 10 from the light source LS of the exposure apparatus (see Figures 1B and 1C), causing it to reflect. The reflected light L2 then irradiates the photoresist layer 120 of the irradiated area SH.

[0069] In this way, the photoresist layer 120 is exposed in approximately half of the remaining area of ​​the irradiated area SH. As described above, the area exposed by the other photomask 10 is referred to as the exposure area EX2.

[0070] In the exposure area EX2, a pattern with a shape similar to the light-shielding pattern P1 of another photomask 10 is transferred in the photoresist layer 120.

[0071] Furthermore, in the double-exposed exposure area Dex where exposure areas EX1 and EX2 overlap, the amount of light in each exposure can be suppressed by the splicing area ST of each pair of photomasks 10. Therefore, at the end of the second exposure stage, the accumulated amount of light is approximately equal to that of the area outside exposure areas EX1 and EX2, and the photosensitivity of the photoresist layer 120 is also approximately equal to that of other areas.

[0072] As shown in Figure 4B, by developing the photoresist layer 120 exposed using two photomasks 10, a resist pattern 120p with the light-shielding pattern P1 of the photomasks 10 transferred on it can be obtained. Thanks to the stitching area ST function of the photomasks 10, even in the double-exposed exposure area Dex, the size conversion difference of the resist pattern 120p can be reduced.

[0073] Based on the above, the exposure process using the photomask 10 in Embodiment 1 is complete.

[0074] Subsequently, the resist pattern 120p obtained by heat treatment and development after exposure is used to process the processed layer 110 on the wafer 100.

[0075] Figures 5A-5D are cross-sectional views illustrating part of the sequence of processing methods for wafer 100 in Embodiment 1.

[0076] As shown in Figure 5A, the resist pattern 120p is used as a mask, and the workpiece layer 110 is processed by means of RIE, for example, to form a workpiece layer 110t having a plurality of grooves TR.

[0077] As shown in Figure 5B, the resist pattern 120p is removed by ashing using oxygen plasma or the like.

[0078] As shown in Figure 5C, a conductive layer 130, such as a Cu layer, is filled into the groove TR of the processed layer 110. The conductive layer 130 is also formed by covering the upper surface of the processed layer 110.

[0079] As shown in Figure 5D, the conductive layer 130 covering the upper surface of the processed layer 110t is removed by chemical mechanical polishing (CMP). This forms a plurality of wirings 130w filled with the conductive layer 130 within the groove TR of the processed layer 110.

[0080] Through the above, the pattern formation process of the processed layer 110 and the processing of the wafer 100 in Embodiment 1 are completed.

[0081] The wiring 130w formed as described above becomes, for example, part of a semiconductor device. That is, the exposure method using the photomask 10 of Embodiment 1, as shown in Figures 3A to 5D, and the patterning process for the processed layer 110 are included in the manufacturing method of the semiconductor device.

[0082] (Summary) To maintain the exposure area on a wafer formed by mask exposure with a mask magnification of, for example, 4×4 at low NA exposure, the mask magnification becomes, for example, 4×8 in high NA-EUV exposure. While maintaining the current mask size, sometimes an exposure process is performed by combining two masks of approximately the same size using a splicing technique. In this case, to match the transfer patterns spanning the two exposure areas, a portion of these exposure areas may overlap. At this point, the double-exposure portion created at the seam between the exposure areas of the two masks results in increased dimensionality differences in the transfer patterns, which becomes a problem.

[0083] Therefore, proposals include, for example, not configuring fine patterns or patterns that require precise control of size conversion differences in the stitching area (Stitching Band); adjusting the resolution of the stitching area to obtain appropriate resolution through double exposure (At-Resolution Stitching); or applying a gradient of light intensity to the stitching area by controlling the on / off state of the light source during exposure (Dose-Gradient Stitching).

[0084] However, the first method requires significant design changes, the second method is prone to process changes, and the third method is difficult to obtain the positional accuracy of the on / off light source.

[0085] According to embodiment 1, the photomask 10 is configured such that the intensity of the reflected light for exposure decreases from the end E31 of the splicing area ST located inside the photomask 10 toward the other end E32 of the splicing area ST located on one side of the photomask 10, at the end E12. This suppresses the size conversion difference caused by double exposure due to the overlap of exposure areas EX1 and EX2.

[0086] According to the photomask 10 of Embodiment 1, the coverage of the light-shielding pattern P2 increases from the end E31 of the splicing area ST located inside the photomask 10 towards the other end E32 of the splicing area ST located on one side of the photomask 10, at the end E12. This reduces the intensity of reflected light for exposure, suppressing the size conversion difference caused by double exposure due to the overlap of exposure areas EX1 and EX2.

[0087] According to the photomask 10 of Embodiment 1, in the light-shielding pattern P22a, the number of dots per unit area increases from the end E31 of the splicing area ST located inside the photomask 10 towards the other end E32 of the splicing area ST located on one side of the photomask 10, E12. This increases the coverage of the light-shielding pattern P22a towards the end E12 of the photomask 10, reducing the intensity of light reflection for exposure.

[0088] According to the photomask 10 of Embodiment 1, in the light-shielding pattern P22b, the area of ​​each point increases from the end E31 of the splicing area ST located inside the photomask 10 towards the other end E32 of the splicing area ST located on one side of the photomask 10, E12. This increases the coverage of the light-shielding pattern P22b towards the end E12 of the photomask 10, reducing the intensity of light reflection for exposure.

[0089] According to the photomask 10 of Embodiment 1, in the light-shielding pattern P22c, the number of dots per unit area and the area of ​​each dot increase from the end E31 of the splicing area ST located inside the photomask 10 towards the other end E32 of the splicing area ST located on one side of the photomask 10, E12. This increases the coverage of the light-shielding pattern P22c towards the end E12 of the photomask 10, reducing the intensity of light reflection for exposure.

[0090] According to the photomask 10 of Embodiment 1, in the light-shielding pattern P21a, the number of lines per unit area increases from the end E31 of the splicing area ST located inside the photomask 10 towards the other end E32 of the splicing area ST located on one side of the photomask 10, E12. This increases the coverage of the light-shielding pattern P21a towards the end E12 of the photomask 10, reducing the intensity of light reflection for exposure.

[0091] According to the photomask 10 of Embodiment 1, in the light-shielding pattern P21b, the width of each line increases from the end E31 of the splicing area ST located inside the photomask 10 towards the other end E32 of the splicing area ST located on one side of the photomask 10, E12. This increases the coverage of the light-shielding pattern P21b towards the end E12 of the photomask 10, reducing the intensity of light reflection for exposure.

[0092] According to the photomask 10 of Embodiment 1, in the light-shielding pattern P21c, the number of lines per unit area and the width of each line increase from the end E31 of the splicing area ST located inside the photomask 10 towards the other end E32 of the splicing area ST located on one side of the photomask 10, E12. This increases the coverage of the light-shielding pattern P21c towards the end E12 of the photomask 10, reducing the intensity of light reflection for exposure.

[0093] (Variation Example 1) In embodiment 1 described above, the coverage of the light-shielding pattern P2 is changed to alter the reflection intensity in the splicing area ST of the photomask 10. However, the method for altering the reflection intensity of the photomask is not limited to this.

[0094] The following uses Figures 6A to 6D to illustrate an example of how the reflection intensity of a photomask can be changed by varying the thickness of the light-absorbing layer 15 of the light-shielding pattern P3.

[0095] Figures 6A-6D are schematic diagrams showing an example of the configuration of the photomask prepared on the opposite side of the wafer in Embodiment 1, of Variation 1. More specifically, Figure 6A is a top view showing an example of the configuration of the light-shielding patterns P1 and P3, and Figures 6B-6D are cross-sectional views showing an example of the configuration of the light-shielding patterns P1 and P3.

[0096] Additionally, in Figures 6A to 6D, there are instances where the same symbols are used to label the same components as in Embodiment 1 above, and their descriptions are omitted.

[0097] As shown in Figures 6A to 6D, the light-shielding pattern P3 is the same as the light-shielding pattern P1, and is composed of a light-absorbing layer 15 and a buffer layer 14 disposed on the reflective layer 13. In the splicing area STa of the photomask in Variation Example 1, it is disposed between the light-shielding patterns P1.

[0098] Furthermore, the thickness of the light-absorbing layer 15 in the light-shielding pattern P1 is constant. In contrast, in the light-shielding pattern P3, the thickness of the light-absorbing layer 15 is configured such that it gradually increases from the end E31 of the splicing region ST near the center of the photomask toward the other end E32 of the splicing region ST located on one side of the photomask, E12.

[0099] The light-absorbing layer 15 has a predetermined absorption rate relative to the exposure light. The amount of exposure light that reaches the reflective layer 13 without being absorbed by the light-absorbing layer 15 varies depending on the thickness of the light-absorbing layer 15. More specifically, the thinner the light-absorbing layer 15, the easier it is for the exposure light to reach the reflective layer 13 without being absorbed; the thicker the light-absorbing layer 15, the more difficult it is for the exposure light to reach the reflective layer 13 after being absorbed. Therefore, by increasing the thickness of the light-absorbing layer 15 towards the end E12 of the photomask, the amount of exposure light reaching the reflective layer 13 is reduced, thereby reducing the reflection intensity per unit area of ​​the photomask 10.

[0100] In the example shown in Figure 6C, the light-shielding pattern P31, which is the light-shielding pattern P3, has a gently sloping inclined surface 15t, thereby gradually thickening from one end E31 of the splicing region STa toward the other end E32. At this time, the light-shielding pattern P31 can be constructed as follows: in the end E31 of the splicing region STa near the center of the photomask, the thickness of the light-absorbing layer 15 is minimized or approximately zero, and at a position at a predetermined distance from the center of the photomask, the thickness of the light-absorbing layer 15 is equal to or greater than that of the light-absorbing layer 15 of the light-shielding pattern P1.

[0101] Such light-blocking patterns P1 and P31 can be formed, for example, as follows.

[0102] A buffer layer 14 and a light-absorbing layer 15 are sequentially formed over the entire reflective layer 13. Furthermore, the portion of the light-absorbing layer 15 that forms the light-shielding patterns P1 and P31 is covered with a resist pattern, and the light-absorbing layer 15 and the buffer layer 14 are sequentially etched under conditions where they form an anisotropic shape, such as a RIE. After temporarily stripping the resist pattern, a further resist pattern is formed that exposes the portion of the light-absorbing layer 15 that forms the inclined surface 15t, and the light-absorbing layer 15 is further etched under conditions where it forms a skirt shape. To form the light-absorbing layer 15 into a skirt shape, methods such as using conditions that easily accumulate etching byproducts or using conditions with low selectivity to the resist pattern can be employed to allow the resist pattern to recede during etching.

[0103] Through the above, a light-shielding pattern P1 with a generally vertical light-absorbing layer 15 and a buffer layer 14 is formed, and a light-shielding pattern P31 with a skirt shape of a light-absorbing layer 15 having an inclined surface 15t is formed.

[0104] In the example shown in Figure 6D, the light-shielding pattern P32, which serves as the light-shielding pattern P3, replaces the gently sloping surface 15t and has a stepped portion 15s in a stepped shape, thereby gradually thickening from one end E31 of the splicing region STa toward the other end E32. At this time, the light-shielding pattern P32 can also be constructed as follows: at the end E31 of the splicing region STa near the center of the photomask, the thickness of the light-absorbing layer 15 is minimized or approximately zero, and at a position at a predetermined distance from the position near the center of the photomask, the thickness of the light-absorbing layer 15 becomes equal to or greater than that of the light-absorbing layer 15 of the light-shielding pattern P1.

[0105] Such light-blocking patterns P1 and P32 can be formed, for example, as follows.

[0106] The process of forming the light-shielding pattern P1 until the first resist pattern is temporarily formed can be performed in the same way as the light-shielding pattern P31 described above. After temporarily peeling off the resist pattern, a resist pattern is further formed to expose a portion of the light-absorbing layer 15 that becomes the stepped portion 15s, and the thinning of the resist pattern and the etching of the light-absorbing layer 15 are repeated several times.

[0107] Through the above, a light-shielding pattern P1 with a generally vertical shape of light-absorbing layer 15 and buffer layer 14, and a light-shielding pattern P31 with a light-absorbing layer 15 having a stepped portion 15s are formed.

[0108] According to the photomask of Variation Example 1, in the light-shielding pattern P3, the light-absorbing layer 15 thickens from the end E31 of the splicing area STa located inside the photomask of Variation Example 1 toward the other end E32 of the splicing area STa located at the end E12 on one side of the photomask.

[0109] This allows the amount of light absorbed by the light-shielding pattern P3 towards the end E12 of the photomask in Variation Example 1 to increase, thereby reducing the intensity of light reflection in the photomask of Variation Example 1. Therefore, the size conversion difference caused by double exposure due to the overlap of exposure areas EX1 and EX2 can be suppressed.

[0110] According to the photomask of Variation Example 1, in the light-shielding pattern P31, the light-absorbing layer 15 has an inclined surface 15t. The inclined surface 15t slopes gently from the end E31 of the splicing area STa located inside the photomask of Variation Example 1 toward the other end E32 of the splicing area STa located on one side of the photomask, E12. In this way, the amount of light absorbed by the light-shielding pattern P31 for exposure can be increased toward the end E12 of the photomask of Variation Example 1, thereby reducing the intensity of light reflection for exposure in the photomask of Variation Example 1.

[0111] According to the photomask of Variation Example 1, in the light-shielding pattern P32, the light-absorbing layer 15 gradually thickens from the end E31 of the splicing area STa located inside the photomask of Variation Example 1 toward the other end E32 of the splicing area STa located on one side of the photomask, E12. This increases the amount of light absorbed by the light-shielding pattern P32 toward the end E12 of the photomask of Variation Example 1, thereby reducing the intensity of light reflection in the photomask of Variation Example 1.

[0112] According to the photomask of Variation Example 1, it also performs the same effect as Embodiment 1 described above.

[0113] (Variation Example 2) Next, as another method to change the reflection intensity of the photomask, the photomask 10b of variation example 2 will be explained using Figures 7A to 7C.

[0114] Figures 7A and 7C are schematic diagrams showing one example of the configuration of the photomask 10b in variation 2 of embodiment 1. More specifically, Figure 7A is a cross-sectional view of the photomask 10b with the protective film 20 installed, and Figures 7B and 7C are enlarged cross-sectional views showing several examples of the reflective layer 13b provided by the photomask 10b.

[0115] Additionally, in Figures 7A to 7C, there are instances where the same symbols are used to label the same components as in Embodiment 1 described above, and their descriptions are omitted.

[0116] As shown in Figure 7A, the photomask 10b replaces the reflective layer 13 of Embodiment 1 described above, and has a reflective layer 13b (131b, 132b) that thins towards the end E12 of the photomask 10b. For example, the photomask 10b has a light-shielding pattern P1 similar to Embodiment 1, and the reflective layer 13b exposed from the light-shielding pattern P1 thins towards the end E12 of the photomask 10b.

[0117] In the reflective layer 13b, the reflectivity of exposure light, such as EUV, varies depending on its thickness. More specifically, the reflective layer 13b is similar to the reflective layer 13 in Embodiment 1 described above, for example, having a multilayer structure in which a plurality of Mo layers and a plurality of Si layers are stacked alternately, and the exposure light is diffracted through these layers and reflected outward from the reflective layer 13b. Therefore, the thinner the reflective layer 13b, the fewer the number of stacked layers, and the lower the reflectivity of the exposure light; the thicker the reflective layer 13b, the more stacked layers, and the higher the reflectivity of the exposure light.

[0118] This reduces the thickness of the reflective layer 13b towards the end E12 of the photomask 10b, thereby reducing the reflectivity of the light used for exposure and reducing the reflection intensity per unit area of ​​the photomask 10b.

[0119] In the example shown in Figure 7B, the reflective layer 131b, which serves as the reflective layer 13b, has a gently sloping inclined surface 13t, thereby gradually thinning from one end E31 of the splicing region STb toward the other end E32. The reflective layer 131b can be configured such that its thickness is maximized at the end E31 of the splicing region STb near the center of the photomask 10b, thus achieving a thickness sufficient for the reflectivity of the photoresist layer and the like. At the end E12 of the photomask 10b, the thickness of the reflective layer 131b is minimized or approximately zero.

[0120] This reflective layer 131b can be formed, for example, as follows.

[0121] A reflective layer 13, identical to that in Embodiment 1, is formed over the entire surface of the glass substrate 12. A resist pattern is formed that exposes the portion of the reflective layer 131b that becomes the inclined surface 13t. The reflective layer 13 is then etched under conditions that form a skirt shape. To set the reflective layer 13b to a skirt shape, methods such as using conditions that easily accumulate etching byproducts or using conditions with low selectivity for the resist pattern can be employed to cause the resist pattern to recede during etching.

[0122] Through the above, a reflective layer 131b with a skirt shape having an inclined surface 13t is formed.

[0123] In the example shown in Figure 7C, the reflective layer 132b, which serves as the reflective layer 13b, replaces the gently sloping surface 13t and has a stepped portion 13s in a stepped shape, thereby gradually thinning from one end E31 of the splicing region STb towards the other end E32. This shape of the reflective layer 132b is obtained, for example, by processing the Mo layer and Si layer contained in the reflective layer 132b into a stepped shape in multiple layers.

[0124] At this point, the reflective layer 132b can be configured as follows: at the end E31 of the splicing area STb near the center of the photomask 10b, the number of layers of the reflective layer 132b is maximized, so that a sufficient number of layers with reflectivity for exposure of photoresist layers, etc., can be obtained; at the end E12 of the photomask 10b, the number of layers of the reflective layer 132b is minimized or approximately zero.

[0125] This reflective layer 132b can be formed, for example, as follows.

[0126] A reflective layer 13 of embodiment 1 is formed on the entire surface of the glass substrate 12, and a resist pattern is formed to expose a portion of the reflective layer 132b that becomes part of the stepped portion 13s. The resist pattern is thinned and the Mo layer and Si layer of the reflective layer 13 are etched in multiple layers.

[0127] Through the above, a reflective layer 132b with stepped portions 13s is formed.

[0128] Alternatively, when the Mo layer and Si layer of the reflective layer 132 are formed by sputtering or the like, the reflective layer 132 can also be formed in a manner that has a stepped portion 13s during the film formation stage.

[0129] In this case, a shielding plate is placed between the glass substrate 12 forming the reflective layer 132 and the sputtering target. By gradually shifting the position of the shielding plate, the area where sputtered particles adhere and form the Mo and Si layers is gradually narrowed. In this way, a reflective layer 132b with stepped portions 13s is formed.

[0130] According to the photomask 10b of Variation Example 2, the reflective layer 13b is thinned from the end E31 of the splicing area STb located inside the photomask 10b toward the other end E32 of the splicing area STb located on one side of the photomask 10b, at the end E12.

[0131] This reduces the reflectivity of the reflective layer 13b towards the end E12 of the photomask 10b, thereby decreasing the intensity of the reflected light. Therefore, it suppresses the size conversion difference caused by double exposure due to the overlap of exposure areas EX1 and EX2.

[0132] According to the photomask 10b of Variation Example 2, the reflective layer 131b has an inclined surface 13t, which slopes gently from the end E31 of the splicing region STb located inside the photomask 10b toward the other end E32 of the splicing region STb located at the end E12 on one side of the photomask 10b. This reduces the reflectivity of the reflective layer 131b to the exposure light towards the end E12 of the photomask 10b, thereby reducing the intensity of the reflected exposure light.

[0133] According to the photomask 10b in Variation Example 2, by gradually shortening the extension distance between the plurality of Mo layers and Si layers, the reflective layer 132b is progressively thinned from the end E31 of the splicing region STb located inside the photomask 10b toward the other end E32 of the splicing region STb located on one side of the photomask 10b, E12. This reduces the reflectivity of the reflective layer 132b to the exposure light toward the end E12 of the photomask 10b, thereby reducing the intensity of the reflected exposure light.

[0134] According to the photomask 10b of Variation Example 2, it also performs the same effect as Embodiment 1 described above.

[0135] [Implementation Mode 2] In embodiment 1 described above, the reflectivity of the photomasks 10 and 10b is adjusted by varying the components of the photomasks themselves to control the amount of light in the double-exposure exposure area Dex. However, the method for adjusting the amount of light in the double-exposure area is not limited to this.

[0136] Hereinafter, with reference to the drawings, the configuration of Embodiment 2, which adjusts the light intensity of the double-exposure area using a method different from Embodiment 1, will be described in detail. Furthermore, in the following drawings, there are instances where the same symbols are used for configurations identical to those in Embodiment 1, and their descriptions are omitted.

[0137] (Example of the composition of the protective film) Figures 8A and 8B are schematic diagrams showing an example of the configuration of the photomask 10c in Embodiment 2. More specifically, Figure 8A is a cross-sectional view of the photomask 10c with the protective film 20 installed, and Figure 8B is an enlarged cross-sectional view of the protective film 200.

[0138] As shown in Figure 8A, the photomask 10c includes a conductive layer 11, a glass substrate 12, a reflective layer 13, and a light-shielding pattern P1 including a buffer layer 14 and a light-absorbing layer 15. Furthermore, a splicing area STc is provided near the end E12 on one side of the photomask 10c.

[0139] The protective film 200 has a protective layer 210 and a frame 22.

[0140] The protective layer 210 is, for example, a carbon nanotube layer, and its thickness varies in the region PL corresponding to the splicing region STc and through which the exposure light reflected from the splicing region STc passes. More specifically, the protective layer 210 thickens from one end E21 of the region PL corresponding to the splicing region STc toward the other end E22.

[0141] Here, the end E21 in the aforementioned region PL is located at a position corresponding to the end E31 of the splicing region STc near the center of the photomask 10c, and the end E22 in the aforementioned region PL is located at a position corresponding to the other end E32 of the splicing region ST located at the end E12 of the photomask 10c.

[0142] As shown in Figure 8B, the protective layer 210, whose thickness varies as described above, has a stepped portion 210s that has a stepped shape.

[0143] As described above, the protective layer 210 has high transmittance for exposure light such as EUV, but the transmittance of exposure light can be reduced by thickening the protective layer 210. Therefore, by increasing the thickness of the protective layer 210 towards the position corresponding to the end E12 of the photomask 10c, the amount of exposure light reaching the reflective layer 13 through the protective layer 210 is reduced, thereby reducing the reflection intensity per unit area of ​​the photomask 10c.

[0144] Alternatively, the protective film 200 of embodiment 2 may further have an oxidation inhibition layer that covers the protective layer 210 and inhibits the oxidation of the protective layer 210.

[0145] (Manufacturing method of protective film) Next, the manufacturing method of the protective film 200 of Embodiment 2 will be described using Figures 9A to 10F. Figures 9A to 10F are cross-sectional views illustrating a portion of the manufacturing method of the protective film 200 of Embodiment 2 in sequence.

[0146] As shown in Figure 9A, a thin layer 210b, such as a carbon nanotube layer, is formed on a support substrate 320 by means of CVD or the like.

[0147] As shown in Figure 9B, the support substrate 320 with the thin layer 210b formed thereon is immersed in pure water or the like in the immersion tank BT, and the thin layer 210b is peeled off from the support substrate 320.

[0148] As shown in Figure 9C, on a support substrate 310 that is different from the support substrate 320 described above, a thin layer 210a such as a carbon nanotube layer is formed by means of CVD or the like, such that the thin layer 210b is extended by a longer distance than the thin layer 210b, so that the thin layer 210b peeled off as described above overlaps with the thin layer 210a.

[0149] As shown in Figure 9D, a thin layer 210c with a shorter extension distance than the thin layer 210b is formed on the support substrate 320 by CVD, and then immersed in the immersion tank BT for peeling.

[0150] As shown in Figure 9E, the thin layer 210c is overlapped and attached to the thin layer 210b of the support substrate 310.

[0151] As shown in Figures 10A to 10F, the above process is repeated so that thin layers 210d to 210h, such as carbon nanotube layers, are sequentially overlapped and attached to thin layer 210c on the support substrate 310. In this way, a protective layer 210 with a plurality of thin layers 210a to 210h is formed.

[0152] Then, the protective layer 210 is attached to the frame 22.

[0153] Based on the above, the protective film 200 of embodiment 2 is manufactured.

[0154] (Summary) According to the photomask 10c of embodiment 2, the protective layer 210 of the protective film 200 thickens in the region PL of the protective film 200 from the end E21 corresponding to the inner side position of the photomask 10c toward the other end E22 corresponding to the end E12 on one side of the photomask 10c.

[0155] This reduces the amount of light reaching the reflective layer 13 towards the end E12 of the photomask 10c, thereby reducing the intensity of light reflection. Therefore, it suppresses the size conversion difference caused by double exposure due to the overlap of exposure areas EX1 and EX2.

[0156] According to the photomask 10c of embodiment 2, it also performs the same effect as that of embodiment 1.

[0157] Furthermore, in Embodiment 2 described above, the protective layer 210 is, for example, a carbon nanotube layer. However, as described in Embodiment 1, the protective layer 210 in Embodiment 2 can be, for example, a graphene layer, a polyimide layer, a polycrystalline silicon layer, or a silicon carbide layer. Even when using a protective layer 210 made of such materials, the aforementioned effect can be achieved by changing the transmittance of light for exposure through variations in thickness.

[0158] (Variation Example 1) In embodiment 2 described above, thin layers 210a to 201h, such as carbon nanotube layers, are stacked one on top of the other to form a protective layer 210. However, the method for forming the protective layer 210 with varying thickness is not limited to the above.

[0159] In the following variation example 1, using Figures 11A to 15, an example of a method for forming the protective layer 210 in a manner different from that of embodiment 2 will be described. The difference between variation example 1 and embodiment 2 is that the protective layer 210 is formed by impregnation.

[0160] Figures 11A to 15 are cross-sectional views illustrating a portion of the manufacturing method of the protective film 200 of Variation 1 of Embodiment 2. Furthermore, in Figures 11A to 15, sometimes the same symbols are used to label components identical to those in Embodiment 2, and their descriptions are omitted.

[0161] As shown in Figure 11A, a thin layer 210a, such as a carbon nanotube layer, is formed on the support substrate 310 by CVD or the like. However, the thin layer 210a can be formed by impregnation or the like, as detailed below.

[0162] As shown in Figure 11B, a portion of the support substrate 310 with a thin layer 210a is immersed in the carbon nanotube dispersion solution DSP in the immersion tank BT. The carbon nanotube dispersion solution DSP is a liquid in which the fine molecules of carbon nanotubes are dispersed in pure water or organic solvents, and commercially available products can be used.

[0163] As shown in Figure 12, the support substrate 310, which is immersed in the dispersion liquid DSP of carbon nanotubes, is lifted from the dispersion liquid DSP, thereby forming a new thin layer 210b, such as a carbon nanotube layer, covering a portion of the thin layer 210a on the support substrate 310.

[0164] Additionally, at this time, a thin layer 210b can also be formed on the back side of the support substrate 310. The following illustrations and descriptions related to the thin layer formed on the back side of the support substrate 310 by repeating the same process are omitted.

[0165] As shown in Figure 13A, a portion of the support substrate 310, on which thin layers 210a and 210b are formed, is immersed in the dispersion liquid DSP. At this time, the support substrate 310 is immersed to a shallower depth than the treatment shown in Figure 11B.

[0166] As shown in Figure 13B, a new thin layer 210c is formed by lifting the support substrate 310 from the dispersion liquid DSP, which covers a portion of the thin layer 210b.

[0167] As shown in Figure 13C, a portion of the support substrate 310, on which thin layers 210a to 210c are formed, is immersed in the dispersion liquid DSP. At this time, the support substrate 310 is immersed to a shallower depth than the treatment shown in Figure 12.

[0168] As shown in Figure 14A, a new thin layer 210d is formed by lifting the support substrate 310 from the dispersion liquid DSP, covering a portion of the thin layer 210c.

[0169] As shown in Figure 14B, a portion of the support substrate 310, on which thin layers 210a to 210d are formed, is immersed in the dispersion liquid DSP and then lifted out. This forms a new thin layer 210e covering a portion of the thin layer 210d.

[0170] As shown in Figure 15, by repeating the above impregnation process, a protective layer 210 with thin layers 210a~2120h of gradually shortening extension distance can be obtained.

[0171] Then, the protective layer 210 is attached to the frame 22.

[0172] Based on the above, the protective film 200 of embodiment 2 is manufactured.

[0173] According to the manufacturing method of the protective film 200 in Variation 1, a protective film 200 that performs the same effect as Embodiment 2 described above can be obtained.

[0174] (Variation Example 2) In the following Variation Example 2, Figures 16A to 16C are used to describe an example of a method for forming the protective layer 210 in a manner different from that of Embodiment 2 and Variation Example 1. In Variation Example 2, the difference from Embodiment 2 and the like is that the protective layer 210 is formed by compression.

[0175] Figures 16A-16C are cross-sectional views illustrating a portion of the manufacturing method of the protective film 200 in Embodiment 2, Variation 2. Furthermore, in Figures 16A-16C, sometimes the same symbols are used to label components identical to those in Embodiment 2, and their descriptions are omitted.

[0176] As shown in Figure 16A, a layer 210t of the same thickness as the carbon nanotube layer is formed on the support substrate 310. This layer 210t preferably has a low layer density, and can be formed, for example, by spraying the dispersion of the carbon nanotubes (DSP) onto the support substrate 310 using a sprayer (not shown). Alternatively, the layer 210t can be formed through the aforementioned impregnation process.

[0177] Furthermore, a mold 400 with a stepped shape is disposed opposite to layer 210t on the support substrate 310. The mold 400 is made of a material that can be arbitrarily selected from various materials, such as metal, ceramic or resin.

[0178] As shown in Figure 16B, the mold 400 presses layer 210t onto the support substrate 310, compressing and shaping layer 210t. As described above, since layer 210t is formed with a low density, it can be compressed by the mold 400 to form a desired shape. Furthermore, it is preferable to pre-adjust the layer density when forming layer 210t so that it becomes the desired layer density after compression.

[0179] As shown in Figure 16C, the protective layer 210 can be obtained by demolding the mold 400.

[0180] Then, the protective layer 210 is attached to the frame 22.

[0181] Based on the above, the protective film 200 of embodiment 2 is manufactured.

[0182] According to the manufacturing method of the protective film 200 in Variation 2, a protective film 200 that performs the same effect as Embodiment 2 described above can be obtained.

[0183] (Variation Example 3) In the following variation 3, using Figures 17A to 19B, an example of a method for forming the protective layer 210 in a manner different from Embodiment 2 and Variations 1 and 2 will be described. In Variation 3, the difference from Embodiment 2 and the like is that the protective layer 210 is formed by spraying.

[0184] Figures 17A to 19B are cross-sectional views illustrating a portion of the manufacturing method of the protective film 200 in Variation 3 of Embodiment 2. Furthermore, in Figures 17A to 19B, sometimes the same symbols are used to label components identical to those in Embodiment 2, and their descriptions are omitted.

[0185] As shown in Figure 17A, a dispersion of carbon nanotubes and other materials, such as DSP, is sprayed onto a support substrate 310 by a sprayer 510, forming a thin layer 210a of carbon nanotubes and other materials. Furthermore, a shielding plate 520 is disposed above the support substrate 310 on which the thin layer 210a is formed, shielding a portion of the support substrate 310 from the spraying of the dispersion of DSP by the sprayer 510.

[0186] The shielding plate 520 can be made of any material that will not dissolve or deteriorate in the dispersion liquid DSP, such as metal, ceramic or resin.

[0187] As shown in Figure 17B, after forming a thin layer 210b covering a portion of a thin layer 210a by shielding a portion of the support substrate 310, the dispersion liquid DSP is sprayed while the shielding plate 520 is slid to expand the shielding area.

[0188] As shown in Figure 17C, after forming a thin layer 210c covering a portion of the thin layer 210b by expanding the shielding area of ​​the support substrate 310, the DSP dispersion liquid is sprayed while the shielding plate 520 is further slid to further expand the shielding area.

[0189] As shown in Figures 18A to 18C, thin layers 210d to 210f are sequentially formed on the support substrate 310 by repeatedly expanding the shielding area of ​​the shielding plate 520 and spraying the dispersion liquid DSP of the sprayer 510.

[0190] As shown in Figures 19A and 19B, thin layers 210g and 210h are sequentially formed on the support substrate 310 by repeatedly expanding the shielding area of ​​the shielding plate 520 and spraying the dispersion liquid DSP from the sprayer 510. In this way, a protective layer 210 is formed on the support substrate 310.

[0191] Then, the protective layer 210 is attached to the frame 22.

[0192] Based on the above, the protective film 200 of embodiment 2 is manufactured.

[0193] According to the manufacturing method of the protective film 200 in Variation 3, a protective film 200 that performs the same effect as Embodiment 2 described above can be obtained.

[0194] (Variation Example 4) In Embodiment 2 and Variations 1-3 described above, the thickness of the protective layer 210 of the protective film 200 is varied, thereby changing the intensity of reflected light from the photomask 10c and adjusting it to the amount of light in the double-exposure exposure area Dex. However, the method for adjusting the amount of light in the double-exposure area of ​​the protective film is not limited to this.

[0195] In the following variation example 4, using Figures 20A and 20B, a method for adjusting the light intensity of the protective film 200a in a manner different from that in Embodiment 2 and Variations 1-3 will be described.

[0196] Figures 20A and 20B are schematic diagrams showing the configuration of the photomask 10c in variation 4 of embodiment 2. More specifically, Figure 20A is a cross-sectional view of the photomask 10c with the protective film 200a installed, and Figure 20B is an enlarged cross-sectional view of the protective film 200a.

[0197] As shown in Figure 20A, the protective film 200a has a protective layer 21, an oxidation inhibition layer 23, and a frame 22.

[0198] The oxidation suppression layer 23 is, for example, a SiO2 layer or a SiN layer, and is configured to cover the opposing surface of the protective layer 21 to suppress oxidation of the protective layer 21. Furthermore, in Variation 4, the thickness of the oxidation suppression layer 23 varies in the region corresponding to the splicing region STc. More specifically, in the region PL of the protective film 200a, the oxidation suppression layer 23 thickens from the end E21 corresponding to the end E31 near the center of the photomask 10c of the splicing region STc, toward the end E22 corresponding to the other end E32 of the splicing region STc located at the end E12 of the photomask 10c.

[0199] As shown in Figure 20B, the oxidation inhibition layer 23, whose thickness varies as described above, has a stepped portion 23s that has a stepped shape.

[0200] Like the protective layer 21, the oxidation inhibition layer 23 has a higher transmittance than EUV and other exposure light, but the transmittance of the exposure light can be reduced by thickening the oxidation inhibition layer 23. Therefore, by increasing the thickness of the oxidation inhibition layer 23 towards the position corresponding to the end E12 of the photomask 10c, the amount of exposure light reaching the reflective layer 13 is reduced, thereby reducing the reflection intensity per unit area of ​​the photomask 10c.

[0201] Furthermore, the oxidation inhibition layer 23 with this shape can also be formed by CVD and etching.

[0202] According to the photomask 10c of variation 4, the oxidation inhibition layer 23 of the protective film 200a thickens in the region PL of the protective film 200a from the end E21 corresponding to the inner side position of the photomask 10c toward the other end E22 corresponding to the end E12 on one side of the photomask 10c.

[0203] This reduces the amount of light reaching the reflective layer 13 towards the end E12 of the photomask 10c, thereby reducing the intensity of light reflection. Therefore, it suppresses the size conversion difference caused by double exposure due to the overlap of exposure areas EX1 and EX2.

[0204] According to the photomask 10c of variation example 4, it also performs the same effect as embodiment 2 described above.

[0205] While several embodiments of the present invention have been described, these embodiments are provided as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, with omissions, substitutions, and modifications made without departing from the spirit of the invention. These embodiments or variations thereof are included within the scope or spirit of the invention, and are also included within the scope of the invention described in the claims and its equivalents.

[0206] 10, 10b, 10c: Photomask 10-1, 10-2: Photomask 11: Conductive layer 12: Glass substrate 13, 13b, 131b, 132b: Reflective layer 14: Buffer layer 15: Light Absorption Layer 13s, 15s, 23s, 210s: Stepped section 13t, 15t: Inclined surface 20, 200, 200a: Protective film 21, 210: Protective layer 22: Framework 23: Oxidation Inhibition Layer 30: Electrostatic clamp 100: Wafer 110, 110t: Processed layer 120: Photoresist layer 120p: Resist pattern 130: Conductive layer 130W: Wiring 210a~210h: Thin film 210t: layer 310, 320:Support base plate 400: Mold 510: Sprayer 520: Shielding board BT: Impregnation tank DSP: Dispersion E11-1, E11-2, E12, E12-1, E12-2, E21, E22, E31, E32: End EX1, EX2, Dex: Exposure areas L1, L2: Light LS: Light Source P1, P2, P3, P21a~P21c, P22a~P22c, P31, P32: Light-blocking patterns PL: Region SH: Irradiation area ST, STa~STc: splicing area TR: slot

Claims

1. A photomask including a splicing region; the splicing region having: a first end located at a position corresponding to one end of the photomask; and a second end located at a position extending inward from the first end of the photomask at a predetermined distance; and the photomask comprising: a substrate; a reflective layer disposed on a first surface of the substrate for reflecting light; and a light-shielding pattern disposed on a second surface of the reflective layer opposite to the substrate, including a light-absorbing layer for absorbing the light; and the photomask being configured such that, in the splicing region, the intensity of light reflection is lower at the first end than at the second end.

2. The photomask of claim 1, wherein the light-shielding pattern comprises: a first light-shielding pattern disposed on the second surface of the reflective layer including the splicing area; and a second light-shielding pattern disposed on the splicing area of ​​the second surface of the reflective layer; and the coverage of the second light-shielding pattern is greater at the first end side of the splicing area than at the second end side.

3. The photomask as claimed in claim 2, wherein the coverage of the second light-shielding pattern increases in stages from the second end of the splicing area toward the first end.

4. The photomask of claim 2, wherein the first light-shielding pattern is disposed in the region between the aforementioned one end and the other end opposite to the aforementioned one end.

5. The photomask of claim 1, wherein the light-shielding pattern comprises: a first light-shielding pattern disposed on the second surface of the reflective layer including the splicing area; and a second light-shielding pattern disposed on the splicing area of ​​the second surface of the reflective layer; and in the second light-shielding pattern, the light-absorbing layer is thicker at the first end side of the splicing area than at the second end side.

6. The photomask of claim 1, wherein the reflective layer is thinner at the first end side of the splicing area than at the second end side.

7. A photomask comprising: a substrate; a reflective layer disposed on a first surface of the substrate for reflecting light; a light-shielding pattern disposed on a second surface of the reflective layer opposite to the substrate, including a light-absorbing layer for absorbing the light; and a protective film disposed at a predetermined distance from the light-shielding pattern and facing the first surface; wherein the protective film includes a region having a first end at a position corresponding to one end of the substrate, and a second end at a position corresponding to a position extending inward from the first end of the substrate at a predetermined distance; and the protective film having a first layer that thickens from the second end toward the first end.

8. The photomask as claimed in claim 7, wherein the first layer is a protective layer that protects the light-shielding pattern.

9. The photomask of claim 7, wherein the protective film further comprises: a second layer covering the third surface of the first layer opposite to the light-shielding pattern; and the first layer being an oxidation-inhibiting layer that inhibits oxidation of the second layer; and the second layer being a protective layer that protects the light-shielding pattern.

10. An exposure method comprising: using a first photomask to expose a first region extending from one end of an irradiation area disposed on a wafer to a position extending a first distance inward into the irradiation area; and using a second photomask to expose a second region extending from the other end of the irradiation area to a position extending a second distance inward into the irradiation area and reaching a position within the first region, thereby doubling the exposure of a third region located at the center of the irradiation area and exposing the entire irradiation area; wherein the first and second photomasks comprise: a splicing region corresponding to the third region, having a first end at a position corresponding to one end of each of the first and second photomasks, and having a second end at a position extending a predetermined distance inward from the first and second end of each of the first and second photomasks; and wherein the first and second photomasks comprise: a substrate; A reflective layer disposed on a first surface of the substrate to reflect light; and a light-shielding pattern disposed on a second surface of the reflective layer opposite to the substrate, comprising a light-absorbing layer that absorbs the light; and the first and second photomasks are configured such that, in the splicing area, the light reflection intensity is lower at the first end side than at the second end side.

11. An exposure method comprising: using a first photomask to expose a first region extending from one end of an irradiation area of ​​a wafer to a position extending a first distance inward into the irradiation area; and using a second photomask to expose a second region extending from the other end of the irradiation area to a position extending a second distance inward into the irradiation area and reaching a position within the first region, thereby doubling the exposure of a third region located at the center of the irradiation area and exposing the entire irradiation area; wherein the first and second photomasks comprise: a substrate; a reflective layer disposed on a first surface of the substrate for reflecting light; a light-shielding pattern disposed on a second surface of the reflective layer opposite to the substrate, comprising a light-absorbing layer for absorbing the light; and a protective film disposed at a predetermined distance from the light-shielding pattern and facing the first surface; wherein the protective film comprises the following region: Corresponding to the third region mentioned above, a first end is provided at a position corresponding to one end of each of the first and second photomasks, and a second end is provided at a position corresponding to a position that extends inward from one end of each of the first and second photomasks by a predetermined distance; and the protective film has: a first layer that thickens from the second end toward the first end.

Images