Photomask and its manufacturing method

Abstract

This invention provides a photomask substrate, a photomask, and a method for manufacturing a photomask that can reduce the region dependence of light transmittance in a film with a photomask pattern. According to one embodiment, the photomask substrate includes: a substrate; a first transmittance adjustment film disposed on the substrate; a phase-shifting film disposed on the first transmittance adjustment film; and a second transmittance adjustment film disposed on the phase-shifting film. In the photomask substrate, when light of a predetermined wavelength passes through the phase-shifting film, the phase of the light passing through the phase-shifting film and the first transmittance adjustment film differs from the phase of the light passing through the atmosphere by approximately 180 degrees, and the phase of the light passing through the phase-shifting film and the second transmittance adjustment film also differs from the phase of the light passing through the atmosphere by approximately 180 degrees.

Description

Technical Field

[0001] The present invention relates to a photomask substrate, a photomask, and a method for manufacturing the photomask. Prior Technology

[0002] In photomasks used in lithography, the light transmittance in the film forming the photomask pattern can vary depending on the area of ​​the photomask, which may become a problem. Summary of the Invention

[0003] An embodiment of the present invention provides a photomask substrate, a photomask, and a method for manufacturing the photomask, which can reduce the region dependence of light transmittance in a film forming a photomask pattern.

[0004] According to one embodiment, the photomask substrate includes: a substrate; a first transmittance adjustment film disposed on the substrate; a phase-shifting film disposed on the first transmittance adjustment film; and a second transmittance adjustment film disposed on the phase-shifting film. When light of a predetermined wavelength passes through the phase-shifting film in the photomask substrate, the phase of the light passing through the phase-shifting film and the first transmittance adjustment film differs from the phase of the light passing through the atmosphere by approximately 180 degrees, and the phase of the light passing through the phase-shifting film and the second transmittance adjustment film also differs from the phase of the light passing through the atmosphere by approximately 180 degrees. Simple Explanation of the Diagram

[0005] Figure 1 is a cross-sectional view showing the structure of the photomask in the first embodiment. Figures 2(a) and (b) are cross-sectional views (1 / 7) showing the manufacturing method of the photomask in the first embodiment. Figures 3(a) and (b) are cross-sectional views (2 / 7) showing the manufacturing method of the photomask in the first embodiment. Figures 4(a) and (b) are cross-sectional views (3 / 7) showing the manufacturing method of the photomask in the first embodiment. Figures 5(a) and (b) are cross-sectional views (4 / 7) showing the manufacturing method of the photomask in the first embodiment. Figures 6(a) and (b) are cross-sectional views (5 / 7) showing the manufacturing method of the photomask in the first embodiment. Figures 7(a) and (b) are cross-sectional views (6 / 7) showing the manufacturing method of the photomask in the first embodiment. Figures 8(a) and (b) are cross-sectional views (7 / 7) showing the manufacturing method of the photomask in the first embodiment. Figure 9 is a cross-sectional view showing the structure of the photomask in the second embodiment. Figures 10(a) and (b) are cross-sectional views (1 / 8) showing the manufacturing method of the photomask in the second embodiment. Figures 11(a) and (b) are cross-sectional views (2 / 8) showing the manufacturing method of the photomask in the second embodiment. Figures 12(a) and (b) are cross-sectional views (3 / 8) showing the manufacturing method of the photomask in the second embodiment. Figures 13(a) and (b) are cross-sectional views (4 / 8) showing the manufacturing method of the photomask in the second embodiment. Figures 14(a) and (b) are cross-sectional views (5 / 8) showing the manufacturing method of the photomask in the second embodiment. Figures 15(a) and (b) are cross-sectional views (6 / 8) showing the manufacturing method of the photomask in the second embodiment. Figures 16(a) and (b) are cross-sectional views (7 / 8) showing the manufacturing method of the photomask in the second embodiment. Figures 17(a) and (b) are cross-sectional views (8 / 8) showing the manufacturing method of the photomask in the second embodiment. Figure 18 is a cross-sectional view showing the structure of the photomask in the third embodiment. Figures 19(a) and (b) are cross-sectional views (1 / 8) showing the manufacturing method of the photomask in the third embodiment. Figures 20(a) and (b) are cross-sectional views (2 / 8) showing the manufacturing method of the photomask in the third embodiment. Figures 21(a) and (b) are cross-sectional views (3 / 8) showing the manufacturing method of the photomask in the third embodiment. Figures 22(a) and (b) are cross-sectional views (4 / 8) showing the manufacturing method of the photomask in the third embodiment. Figures 23(a) and (b) are cross-sectional views (5 / 8) showing the manufacturing method of the photomask in the third embodiment. Figures 24(a) and (b) are cross-sectional views (6 / 8) showing the manufacturing method of the photomask in the third embodiment. Figures 25(a) and (b) are cross-sectional views (7 / 8) showing the manufacturing method of the photomask in the third embodiment. Figures 26(a) and (b) are cross-sectional views (8 / 8) showing the manufacturing method of the photomask in the third embodiment. Figures 27(a) and (b) are cross-sectional views (1 / 7) showing the manufacturing method of the photomask in the fourth embodiment. Figures 28(a) and (b) are cross-sectional views (2 / 7) showing the manufacturing method of the photomask in the fourth embodiment. Figures 29(a) and (b) are cross-sectional views (3 / 7) showing the manufacturing method of the photomask in the fourth embodiment. Figures 30(a) and (b) are cross-sectional views (4 / 7) showing the manufacturing method of the photomask in the fourth embodiment. Figures 31(a) and (b) are cross-sectional views (5 / 7) showing the manufacturing method of the photomask in the fourth embodiment. Figures 32(a) and (b) are cross-sectional views (6 / 7) showing the manufacturing method of the photomask in the fourth embodiment. Figures 33(a) and (b) are cross-sectional views (7 / 7) showing the manufacturing method of the photomask in the fourth embodiment. Implementation

[0006] Hereinafter, embodiments of the present invention will be described with reference to the figures. In Figures 1 to 33, the same symbols are used to mark the same components, and repeated descriptions are omitted.

[0007] (First Implementation) 1) The light mask in the first implementation form Figure 1 is a cross-sectional view showing the structure of the photomask in the first embodiment.

[0008] The photomask of this embodiment includes a substrate 1, a transmittance adjustment film 2, an HT (Half Tone) film 3, a transmittance adjustment film 4, and a light-shielding film 5. The transmittance adjustment film 2 is an example of the first transmittance adjustment film. The HT film 3 is an example of a phase-shifting film. The transmittance adjustment film 4 is an example of the second transmittance adjustment film.

[0009] Substrate 1 is, for example, a transparent substrate such as a quartz substrate or a glass substrate. Figure 1 shows the X and Y directions, which are parallel to and perpendicular to the surface of substrate 1, and the Z direction, which is perpendicular to the surface of substrate 1. The X, Y, and Z directions intersect each other. In this specification, the +Z direction is treated as the upward direction, and the -Z direction is treated as the downward direction. The -Z direction may be consistent with or inconsistent with the direction of gravity.

[0010] A transmittance adjustment film 2 is formed on the substrate 1. The transmittance adjustment film 2 has the function of significantly changing (reducing) the light transmittance of the photomask in this embodiment. In this embodiment, the light transmittance of the transmittance adjustment film 2 is lower than that of the HT film 3. The transmittance adjustment film 2 in this embodiment has a thickness that is thinner than that of the HT film 3. The transmittance adjustment film 2 is, for example, an HfOx film (hafnium oxide film). The transmittance adjustment film 2 can be a film other than an HfOx film, such as an Hf film or a HfN film (hafnium nitride film), or a monomeric metal film, metal oxide film, or metal nitride film containing Cr (chromium), Al (aluminum), W (tungsten), Ta (tantalum), Mo (molybdenum), Y (yttrium), or Ru (ruthenium). In this embodiment, the light transmittance of the photomask is adjusted by the transmittance adjustment film 2.

[0011] HT film 3 is formed on transmittance adjustment film 2. HT film 3 has the function of significantly changing the phase of light transmitted through the photomask of this embodiment. In this embodiment, the amount of phase change of light transmitted through HT film 3 is greater than the amount of phase change of light transmitted through transmittance adjustment film 2 or the amount of phase change of light transmitted through transmittance adjustment film 4. HT film 3 is, for example, a SiN film (silicon nitride film). HT film 3 may contain Mo atoms along with Si and N atoms. The light transmittance of HT film 3 is, for example, about 6% of the light transmittance of substrate 1. In this embodiment, the phase of light transmitted through the photomask is shifted within HT film 3.

[0012] A transmittance adjustment film 4 is formed on the HT film 3. Like the transmittance adjustment film 2, the transmittance adjustment film 4 significantly changes (reduces) the light transmittance of the photomask in this embodiment. In this embodiment, the light transmittance of the transmittance adjustment film 4 is lower than that of the HT film 3. The transmittance adjustment film 4 in this embodiment has a thickness greater than that of the HT film 3. The transmittance adjustment film 4 is, for example, an HfOx film. The transmittance adjustment film 2 can be a film other than HfOx, such as an Hf film or an HfN film, or a monomeric metal film, metal oxide film, or metal nitride film containing Cr, Al, W, Ta, Mo, Y, or Ru. In this embodiment, the light transmittance of the photomask is adjusted by the transmittance adjustment film 4.

[0013] A light-shielding film 5 is formed on the transmittance adjustment film 4. The light-shielding film 5 has the function of blocking light incident on the photomask of this embodiment. The light-shielding film 5 is, for example, a Cr film.

[0014] Furthermore, the aforementioned transmittance refers to energy transmittance, which is the ratio of the energy of the transmitted light to the energy of the light before transmission. On the other hand, amplitude transmittance represents the ratio of the amplitude of the transmitted light to the amplitude of the light before transmission. Energy transmittance is the square of amplitude transmittance. In this specification, energy transmittance is simply referred to as "transmittance".

[0015] The photomask of this embodiment is shown in Figure 1, and has regions R1, R2, R3, and R4. Region R1 is an example of the first region. Region R2 is an example of the second region. Regions R3 and R4 are examples of the third region.

[0016] Region R1 has a structure comprising a substrate 1, a transmittance adjustment film 2, and an HT film 3, but lacks a transmittance adjustment film 4 and a light-shielding film 5. Specifically, region R1 includes: a patterned portion P1, which includes the transmittance adjustment film 2 and the HT film 3; and a recess (non-patterned portion) H1, which is disposed within the transmittance adjustment film 2 and the HT film 3. Thus, in region R1, the transmittance adjustment film 2 and the HT film 3 form a photomask pattern. The recess H1 penetrates through the HT film 3 and the transmittance adjustment film 2 to reach the substrate 1. Therefore, the side surface of the recess H1 is formed by at least the HT film 3 and the transmittance adjustment film 2, and the bottom surface of the recess H1 is formed by the substrate 1. Region H1 is an example of the first recess. Because the light transmittance of region R1, which lacks the transmittance adjustment film 4, is higher than that of region R2, which has the transmittance adjustment film 4, region R1 is called a bright region (bright photomask).

[0017] Region R2 has a structure comprising a substrate 1, a transmittance adjustment film 2, an HT film 3, and a transmittance adjustment film 4, but without a light-shielding film 5. Specifically, region R2 includes: a patterned portion P2, which includes the HT film 3 and the transmittance adjustment film 4; and a recess (non-patterned portion) H2, which is disposed within the HT film 3 and the transmittance adjustment film 4. Thus, in region R2, the HT film 3 and the transmittance adjustment film 4 form a photomask pattern. The recess H2 penetrates through the transmittance adjustment film 4 and the HT film 3 to reach the transmittance adjustment film 2. Therefore, the side surface of the recess H2 is formed by at least the transmittance adjustment film 4 and the HT film 3, and the bottom surface of the recess H2 is formed by the transmittance adjustment film 2. The recess H2 is an example of a second recess. Because the light transmittance of region R2, which has the transmittance adjustment film 4, is lower than the light transmittance of region R1, which does not have the transmittance adjustment film 4, region R2 is called a dark region (dark photomask). For example, the amplitude transmittance of the dark region is about 70% of the amplitude transmittance of the bright region, and the transmittance (energy transmittance) of the dark region is about 49% of the transmittance of the bright region.

[0018] Region R3 has a structure comprising a substrate 1, a transmittance adjustment film 2, an HT film 3, a transmittance adjustment film 4, and a light-shielding film 5. Similarly, region R4 has a structure comprising a substrate 1, a transmittance adjustment film 2, an HT film 3, a transmittance adjustment film 4, and a light-shielding film 5. Regions R3 and R4 form the light-shielding frame of the photomask of this embodiment. As shown in FIG1, region R3 has a patterned portion P3 including the light-shielding film 5, but does not have a recess. On the other hand, region R4 has: a patterned portion P4, which includes the light-shielding film 5; and a recess (non-patterned portion) H4, which is disposed within the light-shielding film 5, the transmittance adjustment film 4, the HT film 3, and the transmittance adjustment film 2. In regions R3 and R4, the light-shielding film 5 has a light-shielding pattern formed. In addition, the light-shielding frame in this embodiment has region R4, but it may also not have region R4. That is, the light-shielding frame may or may not have the recess H4.

[0019] The transmittance adjustment film 2, HT film 3, and transmittance adjustment film 4 of this embodiment are formed to have specified properties (Ar represents argon, F represents fluorine) for light with a specified wavelength, such as ArF excimer laser light (hereinafter referred to as "ArF light"). The wavelength of ArF excimer laser light is 193 nm.

[0020] First, in this embodiment, the transmittance adjustment film 2 and HT film 3 are formed such that the phase of the ArF light transmitted through the transmittance adjustment film 2 and HT film 3 differs from the phase of the ArF light passing through the atmosphere by approximately 180 degrees. Therefore, the phase of the ArF light transmitted through the transmittance adjustment film 2 and HT film 3 becomes a phase that substantially reverses the phase of the ArF light passing through the atmosphere. In this case, the phase of the ArF light transmitted through the patterned portion P1 of region R1 differs from the phase of the ArF light transmitted through the recessed portion H1 of region R1 by approximately 180 degrees. The reason for this is that the patterned portion P1 has the transmittance adjustment film 2 and HT film 3, while the recessed portion H1 does not. Furthermore, the aforementioned "ArF light passing through the atmosphere" here refers to the ArF light passing through the atmosphere at a distance equal to the thickness of the transmittance adjustment film 2 and HT film 3.

[0021] Secondly, in this embodiment, the HT film 3 and the transmittance adjustment film 4 are formed such that the phase of the ArF light transmitted through the HT film 3 and the transmittance adjustment film 4 differs from the phase of the ArF light transmitted in the atmosphere by approximately 180 degrees. Therefore, the phase of the ArF light transmitted through the HT film 3 and the transmittance adjustment film 4 becomes a phase that substantially reverses the phase of the ArF light transmitted in the atmosphere. In this case, the phase of the ArF light transmitted through the patterned portion P2 of region R2 differs from the phase of the ArF light transmitted through the recessed portion H2 of region R2 by approximately 180 degrees. The reason for this is that the patterned portion P2 has the HT film 3 and the transmittance adjustment film 4, while the recessed portion H2 does not. Furthermore, the aforementioned "ArF light transmitted in the atmosphere" here refers to the ArF light transmitted in the atmosphere at a distance equal to the thickness of the HT film 3 and the transmittance adjustment film 4.

[0022] As described above, the photomask of this embodiment includes: a transmittance adjustment film 2 disposed below the HT film 3; and a transmittance adjustment film 4 disposed above the HT film 3. That is, the photomask of this embodiment has transmittance adjustment films 2 and 4 on both sides of the HT film 3, rather than on one side. The effects of the transmittance adjustment films 2 and 4 of this embodiment will be explained below.

[0023] In this embodiment, the patterned portion P1 in region R1 includes an HT film 3 and a transmittance adjustment film 2, and the patterned portion P2 in region R2 includes an HT film 3 and a transmittance adjustment film 4. Therefore, although there is a difference that the transmittance adjustment film 2 is formed below the HT film 3 and the transmittance adjustment film 4 is formed above the HT film 3, both patterned portions P1 and P2 include an HT film and a transmittance adjustment film. This allows the transmittance of patterned portion P1 to be close to that of patterned portion P2, or the amount of phase change within patterned portion P1 to be close to that within patterned portion P2.

[0024] Furthermore, in this embodiment, region R1 has a transmittance adjustment film 2 within the patterned portion P1, while region R2 has a transmittance adjustment film 2 below the patterned portion P2. This allows the transmittance of region R1 to differ from that of region R2. Therefore, region R1 becomes a bright mask, and region R2 becomes a dark mask. According to this embodiment, the optical characteristics of the patterned portions P1 and P2 can be made similar, while the optical characteristics of regions R1 and R2 can be made different.

[0025] Here, we envision a photomask having a transmittance adjustment film 4 but not a transmittance adjustment film 2. In this case, if patterned portion P1 does not have the transmittance adjustment film 4, but patterned portion P2 does, the transmittance of region R1 can be different from that of region R2. However, in this case, the optical characteristics of patterned portions P1 and P2 are also different. The reason for this is that patterned portion P1 only has the HT film 3, while patterned portion P2 has both the HT film 3 and the transmittance adjustment film 4.

[0026] Furthermore, consider the case where the aforementioned photomask has a transmittance adjustment film 2 but not a transmittance adjustment film 4. In this case, if the recess H1 penetrates the transmittance adjustment film 2, while the recess H2 does not, the transmittance of region R1 and region R2 can be different. However, in this case, the optical characteristics of patterned regions P1 and P2 are also different. The reason is that patterned region P1 has both the transmittance adjustment film 2 and the HT film 3, while patterned region P2 only has the HT film 3. The transmittance adjustment film 2 in region R2 is located below patterned region P2, not inside it.

[0027] On the other hand, according to this embodiment, by having both transmittance adjustment films 2 and 4 in the photomask, the optical characteristics of the patterned portions P1 and P2 can be made similar, while the optical characteristics of regions R1 and R2 can be made different. In this way, for example, regions R1 and R2 can be set as halftone masks together, or regions R1 and R2 can function as halftone masks with different characteristics.

[0028] In this embodiment, the photomask pattern is formed in region R1 by a transmittance adjustment film 2 and an HT film 3, and in region R2 by an HT film 3 and a transmittance adjustment film 4. As a result, although there is a difference that the transmittance adjustment film 2 is formed below the HT film 3 and the transmittance adjustment film 4 is formed above the HT film 3, both the pattern portion P1 in region R1 and the pattern portion P2 in region R2 contain both an HT film and a transmittance adjustment film. Therefore, according to this embodiment, the region dependence of light transmittance in the film forming the photomask pattern can be reduced.

[0029] As described above, the photomask of this embodiment has two regions R1 and R2 with different transmittances, which are regions without the light-shielding film 5. On the other hand, the photomask of this embodiment may have three or more regions with different transmittances, which are regions without the light-shielding film 5. For example, the photomask of this embodiment may have a region R1 with high transmittance, a region R2 with low transmittance, and other regions with intermediate transmittance, which are regions without the light-shielding film 5.

[0030] 2) Manufacturing method of the photomask in the first embodiment Figures 2 to 8 are cross-sectional views showing the manufacturing method of the photomask in the first embodiment.

[0031] First, a substrate 1 is prepared, and a transmittance adjustment film 2, an HT film 3, a transmittance adjustment film 4, a light-shielding film 5, and a photoresist film 6 are sequentially formed on the substrate 1 (Fig. 2(a)). As a result, a photomask substrate comprising the substrate 1, the transmittance adjustment film 2, the HT film 3, the transmittance adjustment film 4, the light-shielding film 5, and the photoresist film 6 is manufactured. Fig. 2(a) shows regions R1 to R4 in the same manner as Fig. 1.

[0032] In this embodiment, a photomask substrate comprising a substrate 1, a transmittance adjustment film 2, an HT film 3, and a transmittance adjustment film 4 can be manufactured by a manufacturer, and a light-shielding film 5 and a photoresist film 6 can be sequentially formed on the photomask substrate by another manufacturer. Also, in this embodiment, a photomask substrate comprising a substrate 1, a transmittance adjustment film 2, an HT film 3, a transmittance adjustment film 4, and a light-shielding film 5 can be manufactured by a manufacturer, and a photoresist film 6 can be formed on the photomask substrate by another manufacturer.

[0033] Next, by drawing and developing with EB (Electron Beam), recesses H1, H2, and H4 are formed in the photoresist film 6 in regions R1, R2, and R4, respectively (Figure 2(b)).

[0034] Next, the light-shielding film 5 is fabricated using RIE (Reactive Ion Etching) on ​​the photoresist film 6 (Fig. 3(a)). As a result, the pattern of the photoresist film 6 is transferred onto the light-shielding film 5, and the recesses H1, H2, and H4 are also formed within the light-shielding film 5. The RIE in the step of Fig. 3(a) is performed using, for example, Cl2 gas and O2 gas (Cl represents chlorine).

[0035] Next, the transmittance adjustment film 4 is processed using the RIE of the photoresist film 6 (Fig. 3(b)). As a result, the pattern of the photoresist film 6 is transferred onto the transmittance adjustment film 4, and the recesses H1, H2, and H4 are also formed within the transmittance adjustment film 4. The RIE in the step of Fig. 3(b) is performed using, for example, BCl3 gas (B represents boron).

[0036] Next, the HT film 3 is processed using the RIE of the photoresist film 6 (Fig. 4(a)). As a result, the pattern of the photoresist film 6 is transferred onto the HT film 3, and the recesses H1, H2, and H4 are also formed within the HT film 3. The RIE in the step of Fig. 4(a) is performed using, for example, SF6 gas and Ar gas (S represents sulfur).

[0037] Next, the photoresist film 6 is peeled off (Fig. 4(b)). Thus, patterned portions P1, P2, P3, and P4 are formed in regions R1, R2, R3, and R4, respectively. In Fig. 4(b), patterned portions P1 to P4 contain the pattern of the light-shielding film 5.

[0038] Next, a photoresist film 7 is formed on the light-shielding film 5 (Fig. 5(a)). The photoresist film 7 is also formed in the recesses H1, H2, and H4.

[0039] Next, the photoresist film 7 was removed from regions R1 and R2 by laser drawing and development (Fig. 5(b)).

[0040] Next, the light-shielding film 5 is processed using the RIE of the photoresist film 7 (Fig. 6(a)). As a result, the pattern of the photoresist film 7 is transferred onto the light-shielding film 5, and the light-shielding film 5 is removed from regions R1 and R2. The RIE in the step of Fig. 6(a) is performed using Cl2 gas and O2 gas.

[0041] Next, the photoresist film 7 is peeled off (Fig. 6(b)). In Fig. 6(b), patterned portions P3 and P4 contain the pattern of the light-shielding film 5, and patterned portions P1 and P2 contain the patterns of the transmittance adjustment film 4 and the HT film 3.

[0042] Next, a photoresist film 8 is formed on the light-shielding film 5 and the transmittance adjustment film 4 (Fig. 7(a)). The photoresist film 8 is also formed in the recesses H1, H2, and H4.

[0043] Next, the photoresist film 8 is removed from the entirety of region R1 and a portion of region R4 by laser mapping and development (Fig. 7(b)).

[0044] Next, transmittance adjustment films 2 and 4 are simultaneously processed using the RIE (Regulatory Erection) of photoresist film 8 (Fig. 8(a)). As a result, recesses H1 and H4 are also formed within the transmittance adjustment film 2, and the transmittance adjustment film 4 is removed from region R1. The RIE in the step of Fig. 8(a) is performed using, for example, BCl3 gas. Furthermore, the light-shielding film 5 exposed from the photoresist film 8 in region R4 functions as a hard mask film during this RIE.

[0045] Next, the photoresist film 8 is peeled off (Fig. 8(b)). In Fig. 8(b), patterned sections P3 and P4 contain the pattern of the light-shielding film 5, patterned section P2 contains the pattern of the transmittance adjustment film 4 and the HT film 3, and patterned section P1 contains the pattern of the HT film 3 and the transmittance adjustment film 2.

[0046] Thus, the photomask shown in Figure 1 is manufactured.

[0047] As described above, in this embodiment, the photomask pattern is formed in region R1 by a transmittance adjustment film 2 and an HT film 3, and in region R2 by an HT film 3 and a transmittance adjustment film 4. As a result, although there is a difference that the transmittance adjustment film 2 is formed below the HT film 3 and the transmittance adjustment film 4 is formed above the HT film 3, both the pattern portion P1 in region R1 and the pattern portion P2 in region R2 contain both an HT film and a transmittance adjustment film. Therefore, according to this embodiment, the region dependence of light transmittance in the film forming the photomask pattern can be reduced.

[0048] (Second Implementation) 1) The light mask in the second implementation form Figure 9 is a cross-sectional view showing the structure of the photomask in the second embodiment.

[0049] The photomask of this embodiment has the same structure as the photomask of the first embodiment. The transmittance adjustment film 2 of this embodiment includes transmittance adjustment films 2a and 2b. Transmittance adjustment film 2a is an example of the first film, and transmittance adjustment film 2b is an example of the second film. Furthermore, the transmittance adjustment film 4 of this embodiment includes transmittance adjustment films 4a and 4b. Transmittance adjustment film 4b is an example of the first film, and transmittance adjustment film 4a is an example of the second film.

[0050] A transmittance adjustment film 2a is formed on substrate 1. Transmittance adjustment film 2a is, for example, a SiN film. A transmittance adjustment film 2b is formed on transmittance adjustment film 2a. Transmittance adjustment film 2b is, for example, an HfOx film. Transmittance adjustment film 2b can be a film other than HfOx, such as an Hf film or an HfN film, or a monomeric metal film, metal oxide film, or metal nitride film containing Cr, Al, W, Ta, Mo, Y, or Ru. In this embodiment, the light transmittance of the photomask is adjusted by transmittance adjustment films 2a and 2b.

[0051] A transmittance adjustment film 4b is formed on the HT film 3. The transmittance adjustment film 4b is, for example, an HfOx film. The transmittance adjustment film 4b can be a film other than HfOx, such as an Hf film or an HfN film, or a monomeric metal film, metal oxide film, or metal nitride film containing Cr, Al, W, Ta, Mo, Y, or Ru. A transmittance adjustment film 4a is formed on the transmittance adjustment film 4b. The transmittance adjustment film 4a is, for example, a SiN film. In this embodiment, the light transmittance of the photomask is adjusted by the transmittance adjustment films 4a and 4b.

[0052] Furthermore, regions R1 to R4 of this embodiment have the same characteristics as regions R1 to R4 of the first embodiment. For example, the transmittance adjustment film 2 and HT film 3 of this embodiment are formed such that the phase of ArF light transmitted through the transmittance adjustment film 2 and HT film 3 differs from the phase of ArF light transmitted through the atmosphere by approximately 180 degrees. Additionally, the HT film 3 and transmittance adjustment film 4 of this embodiment are formed such that the phase of ArF light transmitted through the HT film 3 and transmittance adjustment film 4 differs from the phase of ArF light transmitted through the atmosphere by approximately 180 degrees. Therefore, the photomask of this embodiment can achieve the same effect as the photomask of the first embodiment.

[0053] 2) Manufacturing method of the photomask in the second embodiment Figures 10-17 are cross-sectional views showing the manufacturing method of the photomask in the second embodiment.

[0054] First, a substrate 1 is prepared, and a transmittance adjustment film 2, an HT film 3, a transmittance adjustment film 4, a light-shielding film 5, and a photoresist film 6 are sequentially formed on the substrate 1 (Fig. 10(a)). As a result, a photomask substrate comprising the substrate 1, transmittance adjustment film 2, HT film 3, transmittance adjustment film 4, light-shielding film 5, and photoresist film 6 is manufactured. Fig. 10(a) shows regions R1 to R4, similar to Fig. 9. The transmittance adjustment film 2 is formed by sequentially forming transmittance adjustment films 2a and 2b on the substrate 1. The transmittance adjustment film 4 is formed by sequentially forming transmittance adjustment films 4a and 4b on the HT film 3.

[0055] Next, by drawing and developing with EB, recesses H1, H2, and H4 are formed in the photoresist film 6 in regions R1, R2, and R4, respectively (Fig. 10(b)).

[0056] Next, a light-shielding film 5 is fabricated using a photoresist film 6 via a RIE (Fig. 11(a)). As a result, recesses H1, H2, and H4 are also formed within the light-shielding film 5.

[0057] Next, a transmittance adjustment film 4a is fabricated using a photoresist film 6 via a re-emulation (RIE) process (Fig. 11(b)). As a result, recesses H1, H2, and H4 are also formed within the transmittance adjustment film 4a. The RIE process in Fig. 11(b) is performed using, for example, SF6 gas and Ar gas.

[0058] Next, a transmittance adjustment film 4b is fabricated using a photoresist film 6 via a re-emulation (RIE) process (Fig. 12(a)). As a result, recesses H1, H2, and H4 are also formed within the transmittance adjustment film 4b. The RIE process in Fig. 12(a) is performed using, for example, BCl3 gas.

[0059] Next, HT film 3 was fabricated using RIE of photoresist film 6 (Fig. 12(b)). As a result, recesses H1, H2, and H4 were also formed within HT film 3.

[0060] Next, the photoresist film 6 is peeled off (Fig. 13(a)). Thus, patterned portions P1, P2, P3, and P4 are formed in regions R1, R2, R3, and R4, respectively.

[0061] Next, a photoresist film 7 is formed on the light-shielding film 5 (Fig. 13(b)). The photoresist film 7 is also formed in the recesses H1, H2, and H4.

[0062] Next, the photoresist film 7 is removed from regions R1 and R2 by laser drawing and development (Fig. 14(a)). Then, the light-shielding film 5 is processed using the RIE of the photoresist film 7 (Fig. 14(b)). As a result, the light-shielding film 5 is removed from regions R1 and R2.

[0063] Next, the photoresist film 7 is peeled off (Fig. 15(a)). Then, a photoresist film 8 is formed on the light-shielding film 5 and the transmittance adjustment film 4 (Fig. 15(b)). The photoresist film 8 is also formed in the recesses H1, H2, and H4.

[0064] Next, the photoresist film 8 is removed from the entirety of region R1 and a portion of region R4 by laser mapping and development (Fig. 16(a)).

[0065] Next, a transmittance adjustment film 2b is processed using a photoresist film 8 via a re-emulation (RIE) (Fig. 16(b)). As a result, recesses H1 and H4 are also formed within the transmittance adjustment film 2b. The RIE in the step of Fig. 16(b) is performed using, for example, BCl3 gas.

[0066] Next, transmittance adjustment films 2a and 4a are simultaneously processed using the RIE of photoresist film 8 (Fig. 17(a)). As a result, recesses H1 and H4 are also formed within transmittance adjustment film 2a, and transmittance adjustment film 4a is removed from region R1. The RIE in the steps of Fig. 17(a) is performed using, for example, SF6 gas and Ar gas.

[0067] Next, a transmittance adjustment film 4b is processed using a re-extraction (RIE) of photoresist film 8 (Fig. 17(b)). As a result, the transmittance adjustment film 4b is removed from region R1. The RIE in the step of Fig. 17(b) is performed using, for example, BCl3 gas. Subsequently, photoresist film 8 is peeled off.

[0068] Thus, the photomask shown in Figure 10 is manufactured.

[0069] As described above, in this embodiment, the photomask pattern is formed in region R1 by transmittance adjustment films 2a and 2b and HT film 3, and in region R2 by HT film 3 and transmittance adjustment films 4a and 4b. As a result, although there is a difference that transmittance adjustment films 2a and 2b are formed below HT film 3 and transmittance adjustment films 4a and 4b are formed above HT film 3, both the pattern portion P1 in region R1 and the pattern portion P2 in region R2 contain HT film and transmittance adjustment film. Therefore, according to this embodiment, the region dependence of light transmittance in the film forming the photomask pattern can be reduced.

[0070] (Third Implementation) 1) The light shield of the third implementation form Figure 18 is a cross-sectional view showing the structure of the photomask in the third embodiment.

[0071] The photomask of this embodiment has the same structure as the photomask of the second embodiment. However, the transmittance adjustment film 2 of this embodiment includes a transmittance adjustment film 2b formed on the substrate 1 and a transmittance adjustment film 2a formed on the transmittance adjustment film 2b. In this embodiment, the transmittance adjustment film 2b is an example of the first film, and the transmittance adjustment film 2a is an example of the second film. Furthermore, the photomask of this embodiment includes an etching blocking film 11.

[0072] An etching barrier film 11 is formed between the transmittance adjustment film 2 and the HT film 3. Therefore, in this embodiment, the HT film 3 separates the etching barrier film 11 formed on the transmittance adjustment film 2. The etching barrier film 11 in this embodiment has a thickness that is thinner than that of the HT film 3. The etching barrier film 11 is, for example, an HfOx film. The etching barrier film 11 can be a film other than an HfOx film, such as an Hf film or an HfN film, or a monomeric metal film, metal oxide film, or metal nitride film containing Cr, Al, W, Ta, Mo, Y, or Ru.

[0073] The etch stop film 11 functions as an etch barrier when recesses H1, H2, and H4 are formed within the HT film 3 by the RIE. Therefore, the etch selectivity of the etch stop film 11 relative to the HT film 3 is set to a low value (e.g., 1 / 10 or less). For example, this etch selectivity can be achieved by using the HT film 3 as a SiN film and the etch stop film 11 as an HfOx film.

[0074] Assuming the absence of the etching barrier film 11, when a recess H2 is formed within the HT film 3, there is a risk that the recess H2 may also form within the transmittance adjustment film 2. This is referred to as film reduction in the transmittance adjustment film 2. If the recess H2 within the transmittance adjustment film 2 becomes deeper, there is a risk that the optical characteristics of region R2 may differ from the designed characteristics. On the other hand, according to this embodiment, by forming the etching barrier film 11 between the transmittance adjustment film 2 and the HT film 3, film reduction in the transmittance adjustment film 2 can be suppressed.

[0075] Furthermore, regions R1 to R4 of this embodiment have the same characteristics as regions R1 to R4 of the first embodiment. For example, the transmittance adjustment film 2, the etching barrier film 11, and the HT film 3 of this embodiment are formed such that the phase of ArF light transmitted through the transmittance adjustment film 2, the etching barrier film 11, and the HT film 3 differs from the phase of ArF light transmitted through the atmosphere by approximately 180 degrees. Additionally, the etching barrier film 11, the HT film 3, and the transmittance adjustment film 4 of this embodiment are formed such that the phase of ArF light transmitted through the etching barrier film 11, the HT film 3, and the transmittance adjustment film 4 differs from the phase of ArF light transmitted through the atmosphere by approximately 180 degrees. Therefore, the photomask of this embodiment can achieve the same effect as the photomasks of the first and second embodiments.

[0076] 2) Manufacturing method of the photomask in the third embodiment Figures 19 to 26 are cross-sectional views showing the manufacturing method of the photomask in the third embodiment.

[0077] First, a substrate 1 is prepared, and a transmittance adjustment film 2, an etching barrier film 11, an HT film 3, a transmittance adjustment film 4, a light-shielding film 5, and a photoresist film 6 are sequentially formed on the substrate 1 (Fig. 19(a)). As a result, a photomask substrate comprising the substrate 1, the transmittance adjustment film 2, the etching barrier film 11, the HT film 3, the transmittance adjustment film 4, the light-shielding film 5, and the photoresist film 6 is manufactured. Fig. 19(a) shows regions R1 to R4 in the same manner as Fig. 18. The transmittance adjustment film 2 is formed by sequentially forming transmittance adjustment films 2b and 2a on the substrate 1. The transmittance adjustment film 4 is formed by sequentially forming transmittance adjustment films 4b and 4a on the HT film 3.

[0078] Next, by drawing and developing with EB, recesses H1, H2, and H4 are formed in the photoresist film 6 in regions R1, R2, and R4, respectively (Fig. 19(b)).

[0079] Next, a light-shielding film 5 is fabricated using a photoresist film 6 via a RIE (Fig. 20(a)). As a result, recesses H1, H2, and H4 are also formed within the light-shielding film 5.

[0080] Next, a transmittance adjustment film 4a was fabricated using the RIE of the photoresist film 6 (Fig. 20(b)). As a result, recesses H1, H2, and H4 were also formed within the transmittance adjustment film 4a.

[0081] Next, a transmittance adjustment film 4b was fabricated using the RIE of the photoresist film 6 (Fig. 21(a)). As a result, recesses H1, H2, and H4 were also formed within the transmittance adjustment film 4b.

[0082] Next, the HT film 3 is fabricated using the RIE with photoresist film 6 (Fig. 21(b)). As a result, recesses H1, H2, and H4 are also formed in the HT film 3. At this time, the etch stop film 11 functions as an etch stop to stop the movement of the RIE.

[0083] Next, an etching barrier film 11 is fabricated using a photoresist film 6 via a re-etching process (RIE) (Fig. 22(a)). As a result, recesses H1, H2, and H4 are also formed within the etching barrier film 11. The RIE in the step of Fig. 22(a) is performed using, for example, BCl3 gas.

[0084] Next, the photoresist film 6 is peeled off (Fig. 22(b)). Thus, patterned portions P1, P2, P3, and P4 are formed in regions R1, R2, R3, and R4, respectively.

[0085] Next, a photoresist film 7 is formed on the light-shielding film 5 (Fig. 23(a)). The photoresist film 7 is also formed in the recesses H1, H2, and H4. Then, the photoresist film 7 is removed from regions R1 and R2 by laser drawing and development (Fig. 23(b)).

[0086] Next, the light-shielding film 5 is processed using the RIE of the photoresist film 7 (Fig. 24(a)). As a result, the light-shielding film 5 is removed from regions R1 and R2. Then, the photoresist film 7 is peeled off (Fig. 24(b)).

[0087] Next, a photoresist film 8 is formed on the light-shielding film 5 and the transmittance adjustment film 4 (Fig. 25(a)). The photoresist film 8 is also formed in the recesses H1, H2, and H4. Then, the photoresist film 8 is removed from the entirety of region R1 and a portion of region R4 by laser drawing and development (Fig. 25(b)).

[0088] Next, transmittance adjustment films 2a and 4a are simultaneously processed using the RIE of photoresist film 8 (Fig. 26(a)). As a result, recesses H1 and H4 are also formed within transmittance adjustment film 2a, and transmittance adjustment film 4a is removed from region R1. The RIE in the steps of Fig. 26(a) is performed using, for example, SF6 gas and Ar gas.

[0089] Next, transmittance adjustment films 2b and 4b are simultaneously processed using the re-extrusion (RIE) of photoresist film 8 (Fig. 26(b)). As a result, recesses H1 and H4 are also formed within transmittance adjustment film 2b, and transmittance adjustment film 4b is removed from region R1. The RIE in the steps of Fig. 26(b) is performed using, for example, BCl3 gas. Subsequently, photoresist film 8 is peeled off.

[0090] Thus, the photomask shown in Figure 18 is manufactured.

[0091] As described above, in this embodiment, the photomask pattern is formed in region R1 by a transmittance adjustment film 2, an etch stop film 11, and an HT film 3, and in region R2 by an etch stop film 11, an HT film 3, and a transmittance adjustment film 4. As a result, although there is a difference that the transmittance adjustment film 2 is formed below the HT film 3 and the transmittance adjustment film 4 is formed above the HT film 3, both the pattern portion P1 in region R1 and the pattern portion P2 in region R2 contain both an HT film and a transmittance adjustment film. Therefore, according to this embodiment, the region dependence of light transmittance in the film forming the photomask pattern can be reduced. Furthermore, according to this embodiment, by forming an etch stop film 11 between the transmittance adjustment film 2 and the HT film 3, the reduction of the transmittance adjustment film 2 can be suppressed.

[0092] (Fourth Implementation) Figures 27-33 are cross-sectional views showing the manufacturing method of the photomask according to the fourth embodiment. In this embodiment, a photomask having the structure shown in Figure 1 (first embodiment) is manufactured using a hard mask film 21. The hard mask film 21 is, for example, a SiO2 film.

[0093] First, a substrate 1 is prepared, and a transmittance adjustment film 2, an HT film 3, a transmittance adjustment film 4, a light-shielding film 5, a hard mask film 21, and a photoresist film 6 are sequentially formed on the substrate 1 (Fig. 27(a)). As a result, a photomask substrate comprising the substrate 1, the transmittance adjustment film 2, the HT film 3, the transmittance adjustment film 4, the light-shielding film 5, the hard mask film 21, and the photoresist film 6 is manufactured. Fig. 27(a) shows regions R1 to R4 in the same way as Fig. 1.

[0094] Next, by drawing and developing with EB, recesses H1, H2, and H4 are formed in the photoresist film 6 in regions R1, R2, and R4, respectively (Fig. 27(b)).

[0095] Next, a hard mask film 21 is fabricated using a re-extrusion (RIE) of the photoresist film 6 (Fig. 28(a)). As a result, the pattern of the photoresist film 6 is transferred onto the hard mask film 21, and recesses H1, H2, and H4 are also formed within the hard mask film 21. The RIE in the step of Fig. 28(a) is performed using, for example, SF6 gas and Ar gas. Next, the photoresist film 6 is peeled off (Fig. 28(b)).

[0096] Next, the light-shielding film 5 is processed using the RIE of the hard mask film 21 (Fig. 29(a)). As a result, the pattern of the hard mask film 21 is transferred onto the light-shielding film 5, and the recesses H1, H2, and H4 are also formed within the light-shielding film 5.

[0097] Next, the transmittance adjustment film 4 is processed using the RIE of the hard masking film 21 (Fig. 29(b)). As a result, the pattern of the hard masking film 21 is transferred onto the transmittance adjustment film 4, and the recesses H1, H2, and H4 are also formed in the transmittance adjustment film 4.

[0098] Next, the HT film 3 is processed using the RIE of the hard mask film 21 (Fig. 30(a)). As a result, the pattern of the hard mask film 21 is transferred to the HT film 3, and the recesses H1, H2, and H4 are also formed within the HT film 3. In the step shown in Fig. 30(a), the hard mask film 21 is also removed. Thus, patterned portions P1, P2, P3, and P4 are formed in regions R1, R2, R3, and R4, respectively.

[0099] Next, a photoresist film 7 is formed on the light-shielding film 5 (Fig. 30(b)). The photoresist film 7 is also formed in the recesses H1, H2, and H4.

[0100] Next, the photoresist film 7 is removed from regions R1 and R2 by laser drawing and development (Fig. 31(a)). Then, the light-shielding film 5 is processed using the RIE of the photoresist film 7 (Fig. 31(b)). As a result, the light-shielding film 5 is removed from regions R1 and R2.

[0101] Next, the photoresist film 7 is peeled off (Fig. 32(a)). Then, a photoresist film 8 is formed on the light-shielding film 5 and the transmittance adjustment film 4 (Fig. 32(b)). The photoresist film 8 is also formed in the recesses H1, H2, and H4.

[0102] Next, photoresist film 8 is removed from the entirety of region R1 and a portion of region R4 by laser marking and development (Fig. 32(a)). Then, transmittance adjustment films 2 and 4 are simultaneously processed using the RIE of photoresist film 8 (Fig. 32(b)). As a result, recesses H1 and H4 are also formed within transmittance adjustment film 2, and transmittance adjustment film 4 is removed from region R1. Subsequently, photoresist film 8 is peeled off.

[0103] Thus, the photomask shown in Figure 1 is manufactured.

[0104] As described above, in this embodiment, the photomask pattern is formed in region R1 by a transmittance adjustment film 2 and an HT film 3, and in region R2 by an HT film 3 and a transmittance adjustment film 4. As a result, although there is a difference that the transmittance adjustment film 2 is formed below the HT film 3 and the transmittance adjustment film 4 is formed above the HT film 3, both the pattern portion P1 in region R1 and the pattern portion P2 in region R2 contain both an HT film and a transmittance adjustment film. Therefore, according to this embodiment, the region dependence of light transmittance in the film forming the photomask pattern can be reduced.

[0105] While several embodiments have been described above, these embodiments are merely illustrative and not intended to limit the scope of the invention. The novel substrate, mask, and method described in this specification can be implemented in various other forms. Furthermore, various omissions, substitutions, and modifications can be made to the forms of the substrate, mask, and method described in this specification without departing from the spirit of the invention. The appended claims and their equivalents are intended to include such forms or variations as included in the scope or spirit of the invention. [Related Applications]

[0106] This application claims priority to Japanese Patent Application No. 2023-102059 (filed on June 21, 2023). This application includes all contents of the basic application by reference to that basic application.

[0107] 1:Substrate 2: Transmittance Adjustment Membrane 2a: Transmittance adjustment membrane 2b: Transmittance Adjustment Membrane 3: Halftone film 4: Transmittance Adjustment Membrane 4a: Transmittance Adjustment Membrane 4b: Transmittance Adjustment Membrane 5:Light-shielding film 6: Photoresist film 7: Photoresist film 8: Photoresist film 11: Etching barrier film 21: Rigid mask film H1: concave part H2: concave part H4: concave part P1: Pattern Section P2: Pattern Section P3: Pattern Section P4: Pattern Section R1: Region R2: Region R3: Region R4: Region

Claims

1. A photomask comprising: a first region including a substrate, a first transmittance adjustment film disposed on the substrate, and a phase-shifting film disposed on the first transmittance adjustment film, having a first recess extending through the phase-shifting film and the first transmittance adjustment film to the substrate; and a second region including the substrate, the first transmittance adjustment film, the phase-shifting film, and a second transmittance adjustment film disposed on the phase-shifting film, having a second recess extending through the second transmittance adjustment film and the phase-shifting film to the first transmittance adjustment film.

2. The photomask of claim 1 further comprises: a third region comprising the substrate, the first transmittance adjustment film, the phase shifting film, the second transmittance adjustment film, and a light-shielding film disposed on the second transmittance adjustment film.

3. The photomask of claim 1, wherein at least the first or second transmittance adjustment film comprises a first film and a second film disposed on the first film.

4. The photomask of claim 1, wherein the first and second regions further include an etching barrier film disposed between the first transmittance adjustment film and the phase shifting film.

5. A method for manufacturing a photomask, comprising: forming a first region comprising a substrate, a first transmittance adjustment film disposed on the substrate, and a phase-shifting film disposed on the first transmittance adjustment film; forming a first recess in the first region that penetrates the phase-shifting film and the first transmittance adjustment film to the substrate; forming a second region comprising the substrate, the first transmittance adjustment film, the phase-shifting film, and a second transmittance adjustment film disposed on the phase-shifting film; and forming a second recess in the second region that penetrates the second transmittance adjustment film and the phase-shifting film to the first transmittance adjustment film.

6. The method for manufacturing a photomask as claimed in claim 5 further includes: forming a third region comprising the substrate, the first transmittance adjustment film, the phase shifting film, the second transmittance adjustment film, and a light-shielding film disposed on the second transmittance adjustment film.

7. The method of manufacturing a photomask as claimed in claim 6 further includes: forming the first, second, and third regions to include the substrate, the first transmittance adjustment film, the phase shifting film, the second transmittance adjustment film, and the light-shielding film; removing the light-shielding film and the second transmittance adjustment film from the first region; and removing the light-shielding film from the second region.

8. The method of manufacturing a photomask as claimed in claim 7, wherein the second recess is formed in the second transmittance adjustment film and the phase-shifting film before the light-shielding film is removed from the second region, and the first recess is formed in the second transmittance adjustment film and the phase-shifting film before the light-shielding film is removed from the first region, and is formed in the first transmittance adjustment film when or before the second transmittance adjustment film is removed from the first region.

9. The method of manufacturing a photomask as claimed in claim 5, wherein at least the first or second transmittance adjustment film is formed to include a first film and a second film disposed on the first film.

10. The method for manufacturing a photomask as claimed in claim 5, wherein the phase-shifting film is formed on the first transmittance adjustment film.

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