Large-sized photomask

Abstract

To provide a large-sized photomask capable of suppressing irregularities and dimensional variations in a pattern to be transferred onto a transfer target.SOLUTION: A large-sized photomask comprises a translucent substrate and a light-shielding pattern provided on a surface of the translucent substrate, wherein the light-shielding pattern has a laminate structure in which a first low-reflection film, a light-shielding film, and a second low-reflection film are laminated in this order from the translucent substrate side, and wherein a surface of the light-shielding pattern on the translucent substrate side has a reflectance of 8% or less to light in a wavelength region of 313 nm to 436 nm.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a large photomask used to manufacture functional elements for display devices. [Background technology]

[0002] In the field of flat panel displays such as liquid crystal display devices and organic EL display devices, there has been a demand for higher resolution displays and an increase in pixel count in recent years. This has led to a demand for microfabrication of functional elements for display devices, such as TFT substrates and color filters.

[0003] Photolithography using a photomask has been a commonly used method for microfabrication in the manufacture of functional elements for display devices. The photomask generally has a light-shielding pattern formed on the surface of a light-transmitting substrate, and includes light-transmitting and light-shielding regions.

[0004] When such a photomask is used in an exposure apparatus to transfer a pattern onto a transfer target, if the photomask has a high reflectivity with respect to the exposure light, the accuracy of transferring the pattern onto the transfer target decreases due to the influence of stray light caused by the exposure light being reflected off the photomask. To mitigate this problem, techniques have been adopted to reduce the reflectivity of the photomask with respect to the exposure light. Patent Document 1, for example, describes a photomask configuration in which an anti-reflection film is provided on the surface side of a light-shielding pattern.

[0005] Meanwhile, flat panel display manufacturing technology is evolving year by year as resolution becomes increasingly finer. Accordingly, panel manufacturers are developing techniques to form finer patterns with high precision. In recent years, in the field of exposure technology for transferring patterns to a substrate, there has been a trend toward using highly sensitive resists to form finer patterns with high precision. Figure 11 is a graph comparing the variation in transferred line width shift with exposure dose between an existing low-sensitivity resist and a high-sensitivity resist that has been used recently. As shown in Figure 11, the high-sensitivity resist requires a smaller exposure dose for hardening than the low-sensitivity resist, and the variation in transferred line width shift at the low exposure dose stage is larger.

[0006] As a result, with the trend toward using highly sensitive resists, weak stray light, the effect of which would have been negligible in the past, now affects the resist layer during exposure, causing problems such as unevenness and dimensional variations in the pattern transferred to the target object.

[0007] Furthermore, in recent years, when forming a large-area pattern with high precision, the energy of the exposure light irradiated onto the resist layer using exposure light including g-line, h-line, or i-line is insufficient, so there is a demand for using exposure light including light of multiple wavelengths such as g-line, h-line, and i-line, and there is a particular demand for using exposure light including j-line, which has the highest energy among these types of light. On the other hand, when using such exposure light, the resist layer changes significantly during exposure, further increasing the impact of the above-mentioned weak stray light on the resist layer, thereby exacerbating the above-mentioned problems.

[0008] In contrast, the configuration described in Patent Document 1, etc., was unable to sufficiently reduce the intensity of stray light that occurs when exposure light is reflected from the photomask during exposure, and therefore was unable to prevent unevenness and dimensional variations from occurring in the pattern transferred to the transfer target object. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Patent No. 4451391 Summary of the Invention [Problem to be solved by the invention]

[0010] The present disclosure has been made in consideration of the above-mentioned problems, and its main purpose is to provide a large-sized photomask that can suppress unevenness and dimensional variations in the pattern transferred to the transfer target. [Means for solving the problem]

[0011] In order to solve the above problem, the present disclosure provides a large-sized photomask comprising a light-transmitting substrate and a light-shielding pattern provided on the surface of the light-transmitting substrate, wherein the light-shielding pattern has a layered structure in which a first low-reflection film, a light-shielding film, and a second low-reflection film are layered in this order from the light-transmitting substrate side, and the surface of the light-shielding pattern facing the light-transmitting substrate has a reflectance of 8% or less for light in the wavelength range of 313 nm to 436 nm.

[0012] According to the present disclosure, it is possible to suppress unevenness and dimensional variations in a pattern transferred to a transfer receiving body.

[0013] In the above invention, it is preferable that the surface of the light-shielding pattern opposite to the light-transmitting substrate has a reflectance of 10% or less for light in a wavelength range of 313 nm to 436 nm.

[0014] In the above invention, it is preferable that the light-shielding film contains chromium, and the first low-reflection film and the second low-reflection film contain chromium oxide.

[0015] In the above invention, the light-shielding pattern preferably has an optical density (OD) of 4.5 or more for light in the wavelength range of 313 nm to 436 nm.

[0016] In the above invention, the inclination angle of the side surface of the light-shielding film with respect to the light-transmitting substrate is preferably 80 degrees or more and 90 degrees or less, because this can suppress the influence of reflected light of exposure light irradiated onto the side surface of the light-shielding film.

[0017] In the above invention, it is preferable that the side surface of the first low-reflection film or the side surface of the second low-reflection film protrudes in a direction parallel to the surface of the light-transmitting substrate relative to the side surface of the light-shielding film.

[0018] In particular, it is preferable that both the side surfaces of the first low-reflection film and the second low-reflection film protrude in a direction parallel to the surface of the light-transmitting substrate relative to the side surfaces of the light-shielding film, and that the side surfaces of the first low-reflection film protrude in a direction parallel to the surface of the light-transmitting substrate relative to the side surfaces of the second low-reflection film.

[0019] It is also preferable that at least the side surface of the first low-reflection film protrudes in a direction parallel to the surface of the light-transmitting substrate relative to the side surface of the light-shielding film, and that the angle of the side surface of the first low-reflection film with respect to the surface of the light-transmitting substrate is 56° or less, because this makes it easy to remove foreign matter by cleaning and reduces the amount of foreign matter present.

[0020] In the above invention, it is preferable that the side surface of the light-shielding film is concave.

[0021] Furthermore, in the above invention, it is preferable that a division pattern used for division exposure is provided, and that the division pattern is the light-shielding pattern. [Effects of the Invention]

[0022] The present disclosure has the effect of suppressing unevenness and dimensional variations in a pattern transferred to a transfer target. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is a schematic cross-sectional view showing an example of a large-sized photomask according to the present disclosure. [Figure 2] 2 is a schematic cross-sectional view showing a process of transferring a pattern to a resist layer of a transfer target by exposure using the large photomask shown in FIG. 1. FIG. [Figure 3]2 is an enlarged view of the area enclosed by the dashed line in FIG. 1, with the drawing turned upside down. [Figure 4] FIG. 4 is a schematic cross-sectional view showing an area corresponding to FIG. 3 in a large photomask of the prior art. [Figure 5] 4 is a schematic cross-sectional view showing a region corresponding to FIG. 3 in another example of a large-sized photomask according to the present disclosure. [Figure 6] 4 is a schematic cross-sectional view showing a region corresponding to FIG. 3 in another example of a large-sized photomask according to the present disclosure. [Figure 7] 4 is a schematic cross-sectional view showing a region corresponding to FIG. 3 in another example of a large-sized photomask according to the present disclosure. [Figure 8] FIG. 10 is a schematic plan view showing another example of a large-sized photomask according to the present disclosure. [Figure 9] 9 is a schematic plan view showing a pattern transfer body produced from a transfer target body using the large photomask shown in FIG. 8. FIG. [Figure 10] 10A to 10C are schematic cross-sectional views showing a part of the manufacturing process of the pattern transfer member shown in FIG. [Figure 11] 1 is a graph comparing the fluctuation of the transfer line width shift with respect to the exposure dose between an existing low-sensitivity resist and a high-sensitivity resist that has been used recently. [Figure 12] 4 is a schematic cross-sectional view showing a region corresponding to FIG. 3 in another example of a large-sized photomask according to the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0024] The large-sized photomask of the present disclosure will be described in detail below.

[0025] The large-sized photomask of the present disclosure is a large-sized photomask consisting of a light-transmitting substrate and a light-shielding pattern provided on the surface of the light-transmitting substrate, wherein the light-shielding pattern has a layered structure in which a first low-reflection film, a light-shielding film, and a second low-reflection film are layered in this order from the light-transmitting substrate side, and the surface of the light-shielding pattern facing the light-transmitting substrate has a reflectance of 8% or less for light in the wavelength range of 313 nm to 436 nm.

[0026] An example of a large-sized photomask according to the present disclosure will be described with reference to the drawings. Fig. 1 is a schematic cross-sectional view showing an example of a large-sized photomask according to the present disclosure. Fig. 2 is a schematic cross-sectional view showing a process of transferring a pattern to a resist layer of a transfer target by exposure using the large-sized photomask shown in Fig. 1.

[0027] 1, the large-size photomask 100 includes a light-transmitting substrate 110 and a light-shielding pattern 120 provided on a surface 110a of the light-transmitting substrate 110. The light-shielding pattern 120 has a layered structure in which a first low-reflection film 122, a light-shielding film 124, and a second low-reflection film 126 are layered in this order from the light-transmitting substrate 110 side. The reflectance of the surface 120a of the light-shielding pattern 120 facing the light-transmitting substrate 110 is 8% or less for any light in the wavelength range of 313 nm to 436 nm.

[0028] 2, when a pattern is transferred onto a transfer target object 200 having a resist layer 220 formed on a base 210 by exposure using a large photomask 100 and radiating exposure light including light in any of the above wavelength regions from a light source (UV lamp), the intensity of stray light generated by multiple reflections of the exposure light alternately reflected between the surface 120a of the light-shielding pattern 120 facing the light-transmitting substrate 110 and the surface 300a of the exposure light shielding plate 300 or the interface 112 between the light-transmitting substrate 110 and air (not shown) can be reduced, thereby reducing the intensity of stray light La irradiated onto the resist layer 220 in the shielded region where the exposure light is normally blocked by the exposure light shielding plate 300 to, for example, less than 0.3% of the exposure illuminance. This makes it possible to prevent unevenness and dimensional variations in the pattern transferred onto the resist layer 220 in the shielded region.

[0029] Therefore, according to the present disclosure, during exposure using exposure light containing light in any of the above wavelength ranges, the intensity of stray light generated due to the exposure light being reflected off the surface of the light-shielding pattern facing the translucent substrate can be reduced, thereby preventing unevenness and dimensional variations in the pattern transferred to the transfer target.

[0030] Furthermore, in recent years, when forming large-area patterns with high precision in the manufacture of flat panel displays, the energy of the exposure light irradiated onto the resist layer may be insufficient if the exposure light includes g-line (wavelength 436 nm), h-line (wavelength 405 nm), or i-line (wavelength 365 nm). For this reason, there is a demand for the use of exposure light including light of multiple wavelengths such as g-line, h-line, and i-line, and there is a particular demand for the use of exposure light including j-line (wavelength 313 nm), which has the highest energy among these light sources.

[0031] On the other hand, the change in the resist layer upon exposure to exposure light containing light of multiple wavelengths is greater than that of exposure light of a single wavelength, and in particular, the change in the resist layer upon exposure to exposure light containing j-line is greater. Therefore, when using exposure light containing light of multiple wavelengths, especially exposure light containing j-line, the impact of weak stray light on the resist becomes even greater, resulting in a significant problem of unevenness in the pattern transferred to the transfer target. In contrast, in the large-size photomask 100 shown in FIG. 1, the reflectance described above is 8% or less for all light in the above wavelength ranges, so the reflectance of the surface 120a of the light-shielding pattern 120 facing the light-transmitting substrate 110 can be reduced to 8% or less for all light in the g-line, h-line, i-line, and j-line.

[0032] Therefore, according to the present disclosure, during exposure using exposure light including light of multiple wavelengths such as g-line, h-line, and i-line, and particularly exposure light including j-line, it is possible to significantly suppress the occurrence of unevenness in the pattern transferred to the transfer target.

[0033] 1. Light blocking pattern The light-shielding pattern is a light-shielding pattern provided on the surface of the light-transmitting substrate, and has a layered structure in which the first low-reflection film, the light-shielding film, and the second low-reflection film are layered in this order from the light-transmitting substrate side, and the surface of the light-shielding pattern facing the light-transmitting substrate has a reflectance of 8% or less for light in the wavelength range of 313 nm to 436 nm.

[0034] (1) Reflectance for light in the wavelength range of 313 nm to 436 nm The surface of the light-shielding pattern facing the light-transmitting substrate has a reflectance of 8% or less for light in the wavelength range of 313 nm to 436 nm. That is, the reflectance of the surface of the light-shielding pattern facing the light-transmitting substrate is 8% or less for any light in the wavelength range.

[0035] The surface of the light-shielding pattern facing the light-transmitting substrate is not particularly limited as long as it has a reflectance of 8% or less for light in the above wavelength range. Among these, a reflectance of 5% or less for light in the 365-436 nm wavelength range is preferred. During exposure using exposure light containing any light in the 365-436 nm wavelength range, the intensity of stray light La shown in FIG. 2 can be reduced to, for example, less than 0.2% of the exposure illuminance. This allows the intensity of the stray light to be reduced from the level at which the resist layer of the transfer object is exposed to light to a level that does not affect the exposure. Furthermore, a reflectance of 5% or less for light in the 313-365 nm wavelength range is particularly preferred. This is because the same effect can be obtained during exposure using exposure light containing light in a wider wavelength range. More specifically, this effect can be obtained not only with current exposure equipment and resists that use exposure light in the 365-436 nm wavelength range, but also with other exposure equipment and resists that use exposure light in the 313-365 nm wavelength range.

[0036] In the present disclosure, the reflectance of the surface of the light-shielding pattern facing the light-transmitting substrate can be measured using a device (Otsuka Electronics MCPD) that uses a photodiode array as a detector.

[0037] The surface of the light-shielding pattern opposite to the light-transmitting substrate preferably has a reflectance of 10% or less for light in the wavelength range of 313 nm to 436 nm. That is, the surface of the light-shielding pattern opposite to the light-transmitting substrate preferably has a reflectance of 10% or less for any light in the wavelength range.

[0038] The method for measuring the reflectance of the surface of the light-shielding pattern opposite to the light-transmitting substrate is the same as that for measuring the reflectance of the surface of the light-shielding pattern facing the light-transmitting substrate.

[0039] 1, the reflectance of the surface 120b of the light-shielding pattern 120 opposite the light-transmitting substrate 110 is 10% or less for any light in the wavelength range of 313 nm to 436 nm. Therefore, when the large-sized photomask 100 is used to transfer a pattern to a transfer target 200 having a resist layer 220 formed on a substrate 210 by exposure using exposure light including any of the wavelength ranges, as shown in FIG. 2, the intensity of stray light generated by multiple reflections of the exposure light alternately reflected between the surface 120b of the light-shielding pattern 120 opposite the light-transmitting substrate 110 and an interface 212 between the air (not shown) and the resist layer 220, an interface 214 between the resist layer 220 and the substrate 210, etc., can be reduced, and the intensity of stray light Lb irradiated onto the resist layer 220, which would otherwise be blocked from irradiation with the exposure light by the edge portions of the light-shielding pattern 120, can be reduced to, for example, less than 2.0% of the exposure illuminance. This makes it possible to prevent dimensional variations and the like from occurring in the pattern transferred to the resist layer 220 at the edge portions.

[0040] Therefore, a reflectance of 10% or less for light in the above wavelength range is preferred. This is because, during exposure using exposure light including light in any of the above wavelength ranges, the intensity of stray light generated due to the exposure light being reflected off the surface of the light-shielding pattern opposite the light-transmitting substrate can be reduced, thereby effectively suppressing dimensional variations and the like in the pattern transferred to the transfer recipient. In particular, during exposure using exposure light including light of multiple wavelengths such as g-line, h-line, and i-line, especially exposure light including j-line, dimensional variations and the like in the pattern transferred to the transfer recipient can be more significantly suppressed.

[0041] Furthermore, the surface of the light-shielding pattern opposite the light-transmitting substrate preferably has a reflectance of 10% or less for light in the above wavelength range, and more preferably a reflectance of 5% or less for light in the wavelength range of 365 nm to 436 nm. During exposure using exposure light containing any light in the wavelength range of 365 nm to 436 nm, the intensity of stray light Lb shown in FIG. 2 can be reduced to, for example, less than 1.0% of the exposure illuminance. This reduces the intensity of the stray light from the level at the boundary where the resist layer of the transfer target is exposed to light to the extent that dimensional variations occur in the pattern transferred to the resist layer at the edge of the light-shielding pattern to a level where such variations do not occur at all. Furthermore, a reflectance of 5% or less for light in the wavelength range of 313 nm to 365 nm is particularly preferred. This is because similar effects can be obtained during exposure using exposure light containing light in a wider wavelength range. More specifically, the same effect can be obtained not only with current exposure equipment and resists that use exposure light in the wavelength range of 365 nm to 436 nm, but also with other exposure equipment and resists that use exposure light in the wavelength range of 313 nm to 365 nm.

[0042] (2) First low reflection film The first low-reflection film is provided on the light-transmitting substrate side in the laminated structure of the light-shielding pattern, and is a film that has the function of reducing the reflectance of the surface of the light-shielding pattern facing the light-transmitting substrate for light in the wavelength range of 313 nm to 436 nm to 8% or less.

[0043] Because the light-shielding pattern has the first low-reflection film, when light in the above wavelength range is irradiated onto the surface of the light-shielding pattern facing the translucent substrate, the light reflected from the surface of the first low-reflection film facing the translucent substrate, the light reflected from the internal interface of the first low-reflection film, and the light reflected at the boundary between the first low-reflection film and the light-shielding film weaken each other due to interference. This makes it possible to reduce the reflectance of the surface of the light-shielding pattern facing the light-transmitting substrate to 8% or less for light in the wavelength range.

[0044] As described above, when using exposure light including light of multiple wavelengths such as g-line, h-line, and i-line, and particularly exposure light including j-line, the effect of weak stray light on the resist becomes even greater, resulting in a significant problem of unevenness in the pattern transferred to the transfer target. Meanwhile, to solve this problem, it is difficult to form a film that achieves the function of reducing the reflectance of the surface of the light-shielding pattern facing the translucent substrate to light in the wavelength range to 8% or less. Despite these circumstances, the present disclosure makes it possible to form a film that achieves the function of reducing the reflectance of the surface facing the translucent substrate to light in the wavelength range to 8% or less.

[0045] a. 1st low reflection film The thickness of the first low-reflection film is not particularly limited as long as it can realize the function of reducing the reflectance of the surface of the light-shielding pattern facing the light-transmitting substrate to 8% or less for light in the wavelength range, but a thickness within the range of 10 nm to 50 nm is preferable, because if it is too thin, the function of reducing the reflectance decreases, and if it is too thick, it becomes difficult to process the light-shielding pattern with high precision.

[0046] The material of the first low-reflection film is not particularly limited as long as it is a material that can reduce the reflectance of the surface of the light-shielding pattern facing the light-transmitting substrate to 8% or less for light in the wavelength range. For example, chromium oxide (CrO X ), chromium oxide nitride (CrON), chromium nitride (CrN), titanium oxide (TiO), titanium oxide nitride (TiON), tantalum oxide (TaO), tantalum silicide oxide (TaSiO), nickel aluminum oxide (NiAlO), molybdenum silicide oxide (MoSiO), molybdenum silicide oxynitride (MoSiON), etc. Among them, chromium oxide (CrO X ), chromium oxide nitride (CrON), and particularly chromium oxide (CrO X ) is preferred.

[0047] b. Formation method Examples of methods for forming the first low-reflection film include sputtering, vacuum deposition, and ion plating. More specifically, examples include a method in which a Cr target is placed in a vacuum chamber, O2, N2, and CO2 gases are introduced, and a film is formed by reactive sputtering in a vacuum environment. In this method, the ratio of O2 gas is increased compared to when forming a low-reflection film in the light-shielding pattern of a typical binary mask, thereby reducing the reflectance of the surface of the light-shielding pattern facing the transparent substrate to light in the wavelength range of 313 nm to 436 nm to 8% or less.

[0048] (3)Second low reflection film The second low-reflection film is provided on the side opposite the light-transmitting substrate in the laminated structure of the light-shielding pattern, and is a film that has the function of reducing the reflectance of the surface of the light-shielding pattern opposite the light-transmitting substrate for light in the wavelength range of 313 nm to 436 nm.

[0049] By including the second low-reflection film in the light-shielding pattern, when light in the wavelength region is incident on the surface of the light-shielding pattern opposite to the light-transmitting substrate, the light reflected by the surface of the second low-reflection film opposite to the light-transmitting substrate, the light reflected at the internal interface of the second low-reflection film, and the light reflected at the boundary between the second low-reflection film and the light-shielding film weaken each other due to interference, thereby reducing the reflectance of the surface of the light-shielding pattern opposite to the light-transmitting substrate for light in the wavelength region.

[0050] a.Second low reflection film The second low-reflection film is not particularly limited as long as it is a film that has the function of reducing the reflectance of the surface of the light-shielding pattern opposite the light-transmitting substrate for light in the wavelength range of 313 nm to 436 nm, but a film that has the function of reducing the reflectance of the opposite surface for light in the wavelength range of 313 nm to 436 nm to 10% or less is preferred.

[0051] As described above, when using exposure light including light of multiple wavelengths such as g-line, h-line, and i-line, especially exposure light including j-line, the effect of weak stray light on the resist becomes even greater, resulting in significant problems such as dimensional variations in the pattern transferred to the transfer target. Meanwhile, it is difficult to effectively solve this problem by forming an anti-reflection film that reduces the reflectance of the surface of the light-shielding pattern opposite the translucent substrate to 10% or less for light in the wavelength range. Despite these circumstances, the present disclosure makes it possible to form a film that reduces the reflectance of the opposite surface to 10% or less for light in the wavelength range.

[0052] The thickness of the second low-reflection film is not particularly limited as long as it can realize the function of reducing the reflectance of the surface of the light-shielding pattern opposite to the light-transmitting substrate for light in the above wavelength range, but a thickness within the range of 10 nm to 50 nm is preferred, because if it is too thin, the function of reducing the reflectance decreases, and if it is too thick, it becomes difficult to process the light-shielding pattern with high precision.

[0053] The material of the second low-reflection film is the same as that of the first low-reflection film, and therefore a description thereof will be omitted here.

[0054] b. Formation method The method for forming the second low-reflection film, which reduces the reflectance of the surface of the light-shielding pattern opposite the light-transmitting substrate to 10% or less for light in the wavelength range of 313 nm to 436 nm, is the same as the method for forming the first low-reflection film, and therefore will not be described here.

[0055] (4) Light-shielding film The light-shielding film is a film having light-shielding properties that is provided between the first low-reflection film and the second low-reflection film in the laminated structure of the light-shielding pattern.

[0056] a. Light-shielding film The thickness of the light-shielding film is not particularly limited, but is preferably within the range of 80 nm to 180 nm, because if the film is too thin, it becomes difficult to obtain the desired light-shielding properties, and if the film is too thick, it becomes difficult to process the light-shielding pattern with high precision.

[0057] The material for the light-shielding film is not particularly limited as long as it has light-shielding properties, and examples thereof include chromium (Cr), chromium oxynitride (CrON), chromium nitride (CrN), molybdenum silicide oxide (MoSiO), molybdenum silicide oxynitride (MoSiON), tantalum oxide (TaO), tantalum silicide oxide (TaSiO), etc. Among these, chromium (Cr) is preferred.

[0058] b. Light-shielding film formation method Examples of methods for forming the light-shielding film include sputtering, vacuum deposition, and ion plating.

[0059] In addition, methods for forming the light-shielding film that make the optical density (OD) of the light-shielding pattern for light in the above wavelength range 4.5 or more include, for example, a method of extending the time for forming the light-shielding film more than usual or a method of increasing the number of film-forming scans.

[0060] (5) Light blocking pattern a. Optical density (OD) The light-shielding pattern preferably has an optical density (OD) of 4.5 or more for light in the wavelength range of 313 nm to 436 nm, i.e., an optical density (OD) of 4.5 or more for all light in the above wavelength range.

[0061] In the present disclosure, the optical density (OD) for light in the above wavelength range can be measured using an ultraviolet-visible spectrophotometer (Hitachi U-4000).

[0062] In the large-sized photomask 100 shown in FIG. 1, the optical density (OD) of the light-shielding pattern 120 for light in the wavelength range of 313 nm to 436 nm is 4.5 or higher. That is, the optical density (OD) of the light-shielding pattern 120 is 4.5 or higher for any light in that wavelength range. Therefore, as shown in FIG. 2, when the large-sized photomask 100 is used to transfer a pattern to a transfer target 200 having a resist layer 220 formed on a substrate 210 by exposure using exposure light including any light in the above wavelength range, the intensity of transmitted light Lc, which is the exposure light that passes through the light-shielding pattern 120, can be reduced to, for example, 0.001% or less of the exposure illuminance. This makes it possible to prevent unevenness and the like from occurring in the pattern transferred to the resist layer 220.

[0063] Therefore, the optical density (OD) is preferably 4.5 or more. This is because, during exposure using exposure light containing light of any of the above wavelength ranges, the intensity of the transmitted light of the exposure light that passes through the light-shielding pattern can be reduced, thereby effectively suppressing the occurrence of unevenness, etc. in the pattern transferred to the transfer recipient. In particular, during exposure using exposure light containing light of multiple wavelengths such as g-line, h-line, and i-line, particularly exposure light containing j-line, the occurrence of unevenness, etc. in the pattern transferred to the transfer recipient can be effectively suppressed.

[0064] Generally, it is not desirable to increase the optical density (OD) of the light-shielding pattern in a photomask, because the thicker the light-shielding pattern, the more difficult it becomes to process with precision. This tendency is particularly noticeable in photomasks used in the manufacture of semiconductor integrated circuits.

[0065] b. Size (a) Width The width of the light-shielding pattern is, for example, 0.1 μm or more and less than 10.0 μm.The width of the light-shielding pattern is preferably a width whose dimensions are controlled on the submicron order.

[0066] Here, the width of the light-shielding pattern is defined as the dimension in the short direction of the shape in a plan view. The width controlled to the submicron order means a width controlled in units of 0.1 μm, for example, a width of 0.1 μm or more and less than 1.0 μm.

[0067] (b) Film thickness The total film thickness of the light-shielding pattern is not particularly limited, but is preferably in the range of 100 nm to 250 nm, because if it is too thin, it becomes difficult to obtain the desired light-shielding properties, and if it is too thick, it becomes difficult to process the light-shielding pattern with high precision.

[0068] c.Cross-sectional shape The light-shielding pattern preferably has an optical density (OD) of 4.5 or more for light in the above wavelength range and a desired cross-sectional shape. Preferred cross-sectional shapes of the light-shielding pattern will be described below.

[0069] FIG. 3 is an enlarged view of the area enclosed by the dashed line in FIG. 1, with the drawing turned upside down. As shown in Fig. 3, in the large-sized photomask 100 shown in Fig. 1, the optical density (OD) of the light-shielding pattern 120 for light in the wavelength region of 313 nm to 436 nm is 4.5 or higher. In the openings 120c of the light-shielding pattern 120, the inclination angle α of the side surface 124a of the light-shielding film 124 relative to the light-transmitting substrate 110 is 80 degrees or higher and 90 degrees or lower. Meanwhile, Fig. 4 is a schematic cross-sectional view showing the area corresponding to Fig. 3 in a conventional large-sized photomask. As shown in Fig. 4, in the conventional large-sized photomask 100, the inclination angle α of the side surface 124a of the light-shielding film 124 relative to the light-transmitting substrate 110 is less than 80 degrees.

[0070] 3, when the inclination angle α of the side surface 124a of the light-shielding film 124 with respect to the light-transmitting substrate 110 is 80 degrees or more and 90 degrees or less, unlike when the inclination angle α is less than 80 degrees as shown in FIG. 4, there is a high possibility that the reflected light of the exposure light (stray light) irradiated onto the side surface 124a of the light-shielding film 124 from an oblique direction toward the light source during exposure to transfer a pattern to a resist layer of a transfer target object will be guided toward the opening 120c of the light-shielding pattern 120. Therefore, it is possible to prevent the reflected light from being irradiated onto the resist layer where the exposure light is blocked by the edge portion of the light-shielding pattern 120. This makes it possible to prevent dimensional variations and the like from occurring in the pattern transferred to the resist layer at the edge portion.

[0071] Therefore, the light-shielding pattern having an optical density (OD) of 4.5 or more for light in the above wavelength range preferably has a side surface of the light-shielding film inclined at an angle of 80 degrees or more and 90 degrees or less with respect to the light-transmitting substrate, as shown in Fig. 3. By making the light-shielding pattern a thick film to achieve the optical density (OD) of 4.5 or more, even though the amount of reflected light of the exposure light irradiated onto the side surface of the light-shielding film from an oblique direction toward the light source increases, it is possible to suppress dimensional variations and the like in the pattern transferred to the transfer recipient due to the influence of the reflected light.

[0072] The inclination angle of the side surface of the light-shielding film relative to the light-transmitting substrate means the inclination angle of the tangent to the edge of the side surface of the light-shielding film on the side of the light-transmitting substrate, as indicated by α in FIG.

[0073] 5 to 7 are schematic cross-sectional views showing regions corresponding to FIG. 3 in other examples of the large-size photomask of the present disclosure.

[0074] 5, the light-shielding pattern 120 has an optical density (OD) of 4.5 or more for light in the wavelength range of 313 nm to 436 nm. In the openings 120c of the light-shielding pattern 120, the side surfaces 124a of the light-shielding film 124 are flat surfaces perpendicular to the light-transmitting substrate 110, and the side surfaces 122a of the first low-reflection film 122 and the side surfaces 126a of the second low-reflection film 126 protrude by a length L1 from the side surfaces 124a of the light-shielding film 124 in a direction parallel to the light-transmitting substrate 110.

[0075] 6, the light-shielding pattern 120 has an optical density (OD) of 4.5 or higher for light in the wavelength range of 313 nm to 436 nm. In the opening 120c of the light-shielding pattern 120, the side surface 124a of the light-shielding film 124 is a concave surface composed of multiple flat surfaces, and the side surface 122a of the first low-reflection film 122 and the side surface 126a of the second low-reflection film 126 protrude from the side surface 124a of the light-shielding film 124 in a direction parallel to the light-transmitting substrate 110, protruding by a length L2 from the position of the side surface 124a of the light-shielding film 124 farthest from the opening 120c. The side surface 124a of the light-shielding film 124 is constricted by a width W1 in a direction parallel to the light-transmitting substrate 110 from the position closest to the opening 120c to the position farthest from the opening 120c.

[0076] 7, the light-shielding pattern 120 has an optical density (OD) of 4.5 or higher for light in the wavelength range of 313 nm to 436 nm. At the opening 120c of the light-shielding pattern 120, the side surface 124a of the light-shielding film 124 is a concave curved surface. The side surface 124a of the light-shielding film 124 is constricted by a width W2 in a direction parallel to the light-transmitting substrate 110 from the position closest to the opening 120c to the position farthest from it.

[0077] 5 and 6, the side surface 122a of the first low-reflection film 122 and the side surface 126a of the second low-reflection film 126 protrude in a direction parallel to the surface 110a of the light-transmitting substrate 110 relative to the side surface 124a of the light-shielding film 124. Therefore, during exposure to transfer a pattern to a resist layer of a transfer target, the exposure light (stray light) irradiated onto the side surface 124a of the light-shielding film 124 from an oblique direction toward the light source is reduced in intensity by the first low-reflection film 122 before being irradiated onto the side surface 124a of the light-shielding film 124. Furthermore, the reflected light of the exposure light irradiated onto the side surface 124a of the light-shielding film 124 is reduced in intensity by the second low-reflection film 126 before being irradiated onto the resist layer. Therefore, the first low-reflection film 122 and the second low-reflection film 126 can suppress the intensity of exposure light that is irradiated onto the side surface 124a of the light-shielding film 124 from an oblique direction toward the light source when it is irradiated onto the resist layer.

[0078] Therefore, as the light-shielding pattern having an optical density (OD) of 4.5 or more for light in the above wavelength range, it is preferable that the side surface of the first low-reflection film or the side surface of the second low-reflection film protrudes in a direction parallel to the surface of the light-transmitting substrate relative to the side surface of the light-shielding film, as shown in Figures 5 and 6. By making the light-shielding pattern a thick film to achieve the optical density (OD) of 4.5 or more, even though the amount of reflected light of the exposure light irradiated onto the side surface of the light-shielding film from an oblique direction toward the light source increases, it is possible to suppress the occurrence of unevenness in the pattern transferred to the transfer recipient due to the influence of the reflected light.

[0079] Furthermore, the side surface of the first low-reflection film or the side surface of the second low-reflection film that protrudes in a direction parallel to the surface of the light-transmitting substrate relative to the side surface of the light-shielding film is not particularly limited as long as either one of these side surfaces protrudes, but it is preferable that both of these side surfaces protrude.

[0080] Furthermore, when the side surface of the first low-reflection film or the side surface of the second low-reflection film protrudes from the side surface of the light-shielding film in a direction parallel to the surface of the light-transmitting substrate, the protrusion length as shown by L1 and L2 in Figures 5 and 6 is preferably at least half the film thickness of the light-shielding film, because this can effectively prevent unevenness in the pattern transferred to the transfer recipient due to the influence of the reflected light.

[0081] The protrusion length refers to the length by which the side of the first low-reflection film or the side of the second low-reflection film protrudes in a direction parallel to the surface of the light-transmitting substrate from the position on the concave side of the light-shielding film that is farthest from the opening of the light-shielding pattern.

[0082] In the present disclosure, for the following reasons, it is preferable that the side surface of the first low-reflection film or the side surface of the second low-reflection film protrude in a direction parallel to the surface of the light-transmitting substrate relative to the side surface of the light-shielding film.

[0083] That is, a metal film such as chromium generally has a higher polarity than a metal oxide film such as chromium oxide, and therefore tends to have foreign matter adhere thereto easily. Therefore, when the light-shielding film is made of chromium, if the side surface of the light-shielding film protrudes in a direction parallel to the surface of the light-transmitting substrate relative to the side surface of the first low-reflection film or the side surface of the second low-reflection film, there is a high possibility that foreign matter will adhere to the light-shielding film, and it may become difficult to remove the foreign matter by subsequent cleaning.

[0084] From the viewpoint of preventing such adhesion of foreign matter, it is preferable that the side surface of the first low-reflection film or the side surface of the second low-reflection film protrudes in a direction parallel to the surface of the light-transmitting substrate relative to the side surface of the light-shielding film, and it is particularly preferable that both of these side surfaces protrude.

[0085] In the present disclosure, the order of the side surfaces protruding in a direction parallel to the surface of the light-transmitting substrate is preferably such that the side surface of the first low-reflection film protrudes the most, followed by the side surface of the second low-reflection film and the side surface of the light-shielding film. This is because, if a foreign substance is present near the side surface of these laminates, the side surface of the first low-reflection film protrudes the most, and therefore the contact area of the foreign substance with the metal oxide film is large, making contact easier, and as a result, the foreign substance can be easily peeled off.

[0086] On the other hand, in the present disclosure, it is preferable that at least the side surface of the first low-reflection film protrudes in a direction parallel to the surface of the light-transmitting substrate relative to the side surface of the light-shielding film, and further that the angle of the side surface of the first low-reflection film relative to the surface of the light-transmitting substrate is 56° or less.

[0087] Fig. 12 shows a portion of an example of a large-sized photomask of this type. In the large-sized photomask 100 shown in Fig. 12, the side surface 122a of the first low-reflection film 122 and the side surface 126a of the second low-reflection film 126 protrude in a direction parallel to the surface 110a of the light-transmitting substrate 110 relative to the side surface 124a of the light-shielding film 124. The angle α formed between the side surface 122a of the first low-reflection film 122 and the surface 110a of the light-transmitting substrate 110 is 56° or less.

[0088] As described above, by setting the angle of the side surface of the first low-reflection film to the surface of the light-transmitting substrate to 56° or less, even if foreign matter adheres, the area that comes into contact with the cleaning fluid during cleaning can be increased, allowing cleaning to be performed efficiently and preventing problems caused by the presence of foreign matter after the cleaning process.

[0089] Here, the angle of the side of the first low-reflection film relative to the surface of the light-transmitting substrate is an angle obtained by drawing a straight line from position A where the side 122a of the first low-reflection film 122 meets the surface 110a of the light-transmitting substrate 110, to position B where the film thickness of the first low-reflection film 122 begins to decrease, and measuring the angle between this line and the surface 110a.

[0090] Furthermore, the side surface 122a of the first low-reflection film 122 protruding relative to the side surface 124a of the light-shielding film 124 means that the position B at which the film thickness of the first low-reflection film 122 begins to decrease protrudes relative to the side surface 124a of the light-shielding film 124 in a direction parallel to the surface 110a of the light-transmitting substrate 110.

[0091] In the present disclosure, the angle of the side surface of the first low-reflection film relative to the surface of the light-transmitting substrate is preferably 56° or less, and more preferably 40° or less, because this allows for more efficient cleaning. Although a smaller angle is preferable, from the viewpoint of manufacturing difficulty, it is preferable for the angle to be 20° or more.

[0092] In the present disclosure, it is preferable that the side surfaces of the second low-reflection film also protrude further than the side surfaces of the light-shielding film in a direction parallel to the surface of the light-transmitting substrate, because this can reduce adhesion of foreign matter to the side surfaces of the light-shielding film, which may be difficult to remove by cleaning due to the influence of adhesion to the foreign matter.

[0093] 6 and 7, the side surface 124a of the light-shielding film 124 is concave. Therefore, during exposure to transfer a pattern to a resist layer of a transfer target, the reflected light of exposure light (stray light) irradiated onto the side surface 124a of the light-shielding film 124 from an oblique direction toward the light source is likely to be guided toward the light source or the opening 120c of the light-shielding pattern 120. This makes it possible to prevent the reflected light from being irradiated onto the resist layer where the exposure light is blocked by the edge portion of the light-shielding pattern 120. This makes it possible to prevent dimensional variations and the like from occurring in the pattern transferred to the resist layer at the edge portion.

[0094] Therefore, the light-shielding pattern having an optical density (OD) of 4.5 or more for light in the wavelength range is preferably one in which the side surfaces of the light-shielding film are concave, as shown in Figures 6 and 7. This is because, by making the light-shielding pattern a thick film to achieve the optical density (OD) of 4.5 or more, even though the amount of reflected light of the exposure light irradiated onto the side surfaces of the light-shielding film from an oblique direction toward the light source increases, it is possible to suppress the occurrence of dimensional variations in the pattern transferred to the transfer recipient due to the influence of the reflected light.

[0095] Furthermore, as for the light-shielding pattern having a concave side surface of the light-shielding film, it is preferable that the width of the constriction on the side surface of the light-shielding film is equal to or greater than half the film thickness of the light-shielding film as shown by W1 and W2 in Figures 6 and 7. This is because it is possible to effectively suppress the occurrence of dimensional variations in the pattern transferred to the transfer recipient due to the influence of the reflected light.

[0096] The constriction width means the width in a direction parallel to the surface of the light-transmitting substrate from the position closest to the opening of the light-shielding pattern to the position farthest from the opening on the side surface of the light-shielding film.

[0097] d. Boundary structure of low-reflection film and light-shielding film The boundaries between the light-shielding film and the first and second low-reflection films may be clear or unclear. A light-shielding pattern having a clear boundary is preferred because it is easy to control the properties of each film individually. Furthermore, a light-shielding pattern having an unclear boundary is preferred because it results in a smooth processed surface and is easy to fabricate.

[0098] The light-shielding pattern having a clear boundary can be produced by depositing the first low-reflection film, the light-shielding film, and the second low-reflection film separately using a sputtering apparatus with a different gas, while the light-shielding pattern having an unclear boundary can be produced by depositing the first low-reflection film, the light-shielding film, and the second low-reflection film consecutively without changing the gas in the sputtering apparatus.

[0099] e. Formation method Examples of methods for forming the light-shielding pattern include a method in which a light-shielding layer having a laminated structure in which a first low-reflection film, a light-shielding film, and a second low-reflection film are laminated in this order on the surface of synthetic quartz glass, a resist pattern of a desired shape is formed on the surface of the light-shielding layer, and the light-shielding layer is processed by wet etching using the resist pattern as a mask.

[0100] 2.Transparent substrate The size of the above-mentioned light-transmitting substrate may be, for example, a photomask having at least one side of 350 mm or more, and may be appropriately selected depending on the intended use of the large-sized photomask of the present disclosure. Although not particularly limited, the size is preferably 330 mm x 450 mm or more, and more preferably within the range of 330 mm x 450 mm to 1700 mm x 1800 mm.

[0101] The thickness of the light-transmitting substrate can be appropriately selected depending on the material and application of the large-sized photomask, etc. The thickness of the light-transmitting substrate is, for example, about 8 mm to 17 mm.

[0102] The light-transmitting substrate has optical transparency, and a light-transmitting substrate used in a general large-sized photomask can be used. Examples of the light-transmitting substrate include optically polished low-expansion glass (aluminoborosilicate glass, borosilicate glass) and synthetic quartz glass. Among these, synthetic quartz glass is preferably used in the present disclosure because it has a small thermal expansion coefficient and is easy to manufacture into a large-sized photomask. Furthermore, a resin-made light-transmitting substrate can also be used in the present disclosure.

[0103] The light transmittance of the light-transmitting substrate is not particularly limited as long as it is comparable to that of light-transmitting substrates used in general large-sized photomasks, but a transmittance of 80% or more for light in the wavelength range of 313 nm to 436 nm is preferred, with a transmittance of 85% or more, and particularly 90% or more being preferred. This is because a light-transmitting substrate with high purity scatters less light passing through it within the material and also has a low refractive index, thereby suppressing the generation of stray light.

[0104] 3.Other The large-sized photomask of the present disclosure is not particularly limited as long as it comprises the above-mentioned light-transmitting substrate and the above-mentioned light-shielding pattern, and the reflectance of the surface of the light-shielding pattern facing the light-transmitting substrate for light in the above wavelength range is 8% or less. However, it is preferable that the large-sized photomask has a division pattern used for division exposure, and the division pattern is the above-mentioned light-shielding pattern.

[0105] Divided exposure is a method in which the transfer area on the transfer object is divided into multiple exposure areas, each of the multiple exposure areas is exposed individually using a large photomask, and the divided pattern of the photomask is transferred to each of the multiple exposure areas, thereby forming a continuous pattern on the transfer object that is larger than the divided pattern of the photomask.

[0106] Such a preferred large-sized photomask will be described with reference to the drawings. Fig. 8 is a schematic plan view showing another example of the large-sized photomask of the present disclosure. Fig. 9 is a schematic plan view showing a pattern-transferred body produced from a transfer-receiving body using the large-sized photomask shown in Fig. 8. Figs. 10(a) and 10(b) are schematic cross-sectional views showing part of the manufacturing process of the pattern-transferred body shown in Fig. 9.

[0107] 8, the large-sized photomask 100 includes a light-transmitting substrate 110 and a first divided pattern 150a, a second divided pattern 150b, and a third divided pattern 150c that are different from one another and are provided on a surface 110a of the light-transmitting substrate 110. The first divided pattern 150a, the second divided pattern 150b, and the third divided pattern 150c are light-shielding patterns 120 having a layered structure in which a first low-reflection film 122, a light-shielding film 124, and a second low-reflection film 126 are layered in this order from the light-transmitting substrate 110 side, similar to the light-shielding pattern 120 shown in FIG. 1. Therefore, the surfaces of the first divided pattern 150a, the second divided pattern 150b, and the third divided pattern 150c facing the light-transmitting substrate 110 have a reflectance of 8% or less for light in the wavelength range of 313 nm to 436 nm, similar to the light-shielding pattern 120 shown in FIG.

[0108] The pattern transfer body 200' shown in Figure 9 is manufactured by using the large photomask 100 shown in Figure 8 to expose the resist layer 220 of the transferee 200 to exposure light containing any of the light in the above wavelength ranges from a light source (UV lamp) for each of the first divided pattern 150a, the second divided pattern 150b, and the third divided pattern 150c.

[0109] When the pattern transfer body 200' is manufactured, first, in the first exposure, the second divided pattern 150b and the third divided pattern 150c are shielded by an exposure shielding plate 300 (shown in FIG. 10) so that the resist layer 220 is irradiated with the exposure light only through the first divided pattern 150a of the first to third divided patterns. Next, in the second to sixth exposures, the third divided pattern 150c and the first divided pattern 150a are shielded by the exposure shielding plate 300 so that the resist layer 220 is irradiated with the exposure light only through the second divided pattern 150b of the first to third divided patterns. Next, in the seventh exposure, the first divided pattern 150a and the second divided pattern 150b are shielded by the exposure shielding plate 300 so that the resist layer 220 is irradiated with the exposure light only through the third divided pattern 150c of the first to third divided patterns. As a result, one first resist pattern 220a to which the first divided pattern 150a has been transferred, five second resist patterns 220b to which the second divided patterns 150b have been transferred, and one third resist pattern 220c to which the third divided pattern 150c has been transferred are formed so as to be connected in a single direction, resulting in the formation of a continuous single resist pattern.

[0110] 2, in the second exposure described above, as shown in Fig. 10(a), similarly to the process shown in Fig. 2, the intensity of stray light generated due to the exposure light being reflected by the surface 120a of the second divided pattern 150b (light-shielding pattern 120) facing the light-transmitting substrate 110 is reduced, thereby making it possible to reduce the intensity of stray light La irradiated onto the resist layer 220 in the shielded region (third exposure region) where irradiation of the exposure light is normally blocked by the exposure light shielding plate 300. Furthermore, by reducing the intensity of stray light generated due to the exposure light being reflected by the surface 120b of the second divided pattern 150b opposite to the light-transmitting substrate 110, it is possible to reduce the intensity of stray light Lb irradiated onto the resist layer 220 in the second exposure region where irradiation of the exposure light is normally blocked by the edge portion of the second divided pattern 150b.

[0111] In the third exposure described above, as shown in Figure 10(b), by reducing the intensity of stray light in the same manner as in the second exposure, the intensity of stray light Lb that is further irradiated onto the resist layer 220 in the area already irradiated with stray light La in the second exposure can be reduced, and the intensity of stray light La that is further irradiated onto the resist layer 220 in the area already irradiated with stray light Lb in the second exposure can be reduced.

[0112] Therefore, with the above-described preferred large-sized photomask, when a plurality of exposure areas on a transfer target are individually exposed using the large-sized photomask in divided exposure, stray light generated by reflection of the exposure light from each surface of the light-shielding pattern is irradiated onto other exposure areas, resulting in multiple exposure of the resist layer due to the stray light. Even in this case, the intensity of the stray light can be reduced, and therefore unevenness and dimensional variations in the pattern transferred to the transfer target can be significantly suppressed.

[0113] In addition, in divided exposure, multiple exposure may occur in the area where adjacent exposure areas are connected due to the influence of the alignment accuracy of the exposure device. Therefore, if multiple exposure due to the above-mentioned stray light occurs, the problem of unevenness and dimensional variation in the pattern transferred to the transfer target object is likely to become more serious. Therefore, the above-mentioned effects can be obtained even more significantly.

[0114] 4. Large-sized photomask manufacturing method The method for manufacturing the large-sized photomask of the present disclosure is not particularly limited as long as it can manufacture a large-sized photomask having the above-described configuration, and can be the same as the method for manufacturing a general large-sized photomask.

[0115] For example, a mask blank is produced by preparing synthetic quartz glass as a light-transmitting substrate and providing a light-shielding layer having a laminated structure in which a first low-reflection film, a light-shielding film, and a second low-reflection film are laminated in this order on the surface of the synthetic quartz glass. Next, a resist pattern of a desired shape is formed on the surface of the light-shielding layer, and the light-shielding layer is processed by wet etching using the resist pattern as a mask to form a light-shielding pattern from the light-shielding layer. This produces a large-sized photomask. Furthermore, the etching solution used for the wet etching is not particularly limited as long as it can process the light-shielding layer with high precision and does not damage the light-transmitting substrate, but for example, cerium ammonium nitrate solution can be used.

[0116] 5.Applications The large-sized photomask of the present disclosure can be suitably used, for example, in photolithography methods in the manufacture of pattern transfer bodies such as functional elements for display devices used in display devices.

[0117] Examples of functional elements for display devices manufactured using the large photomask of the present disclosure include TFT substrates, substrates with metal wiring used in TFT substrates, color filters, substrates with light-shielding portions used in color filters, and the like.

[0118] The method for manufacturing a pattern transfer body such as a functional element for a display device using the large-sized photomask of the present disclosure is not particularly limited and can be the same as a general manufacturing method using a large-sized photomask. For example, there can be mentioned a manufacturing method including an exposure step of preparing a transfer body having a resist layer, irradiating the resist layer with exposure light through the large-sized photomask to expose the resist layer, and a development step of developing the resist layer after exposure.

[0119] The resist used in the resist layer can be similar to a general resist, and may be a positive resist or a negative resist. Examples of positive resists include novolac resins, phenolic epoxy resins, acrylic resins, polyimides, and cycloolefins. Specific examples include IP3500 (manufactured by TOK Corporation), PFI27 (manufactured by Sumitomo Chemical Co., Ltd.), ZEP7000 (manufactured by Zeon Corporation), and positive resists (manufactured by JSR Corporation). Among these, positive resists (manufactured by JSR Corporation) are preferred because they have high sensitivity, thereby making the effects of the present disclosure more pronounced. On the other hand, examples of negative resists include acrylic resins. Specific examples include polyglycidyl methacrylate (PGMA), chemically amplified SAL601 (manufactured by Cypress), and negative resists (manufactured by JSR Corporation). Among these, negative resists (manufactured by JSR Corporation) are preferred because they have high sensitivity, thereby making the effects of the present disclosure more pronounced. Furthermore, when a functional element for a display device manufactured using the large photomask of the present disclosure uses a resist layer after development as a constituent member, the resist layer may contain colorants such as pigments and dyes, and functional materials such as inorganic oxide microparticles.

[0120] The thickness of the resist layer is not particularly limited, but is, for example, in the range of 10 nm to 10 μm. The method for forming the resist layer can be a known method, and therefore, description thereof will be omitted here.

[0121] The transfer recipient usually has a substrate for forming a resist layer. It may also have a metal layer, etc. The transfer recipient is appropriately selected depending on the type of functional element for a display device to be manufactured.

[0122] The exposure light used in the exposure step is not particularly limited as long as it can react with the resist in the resist layer and contains any light in the wavelength region of 313 nm to 436 nm. The exposure light is preferably exposure light containing light of multiple wavelengths such as g-line, h-line, and i-line, and particularly preferably exposure light containing j-line. This is because the energy of the exposure light irradiated onto the resist layer can be increased, exposure can be completed in a shorter exposure time, and unevenness in the pattern transferred to the transfer target can be significantly suppressed. As the light source of the exposure light, for example, an ultra-high pressure mercury lamp (ultra-high pressure UV lamp) or the like can be used.

[0123] The developing method for the resist layer used in the developing step can be a general method without any particular limitation, and for example, a method using a developer can be suitably used.

[0124] The present disclosure is not limited to the above-described embodiments. The above-described embodiments are merely examples, and any configuration that is substantially identical to the technical idea described in the claims of the present disclosure and that provides similar effects is included within the technical scope of the present disclosure. [Example]

[0125] A. Reflectance and Optical Density First, the reflectance and optical density will be described using examples and comparative examples.

[0126] [Example A1] First, a precisely polished synthetic quartz glass (transparent substrate) with dimensions of 700 mm x 800 mm x 8 mm was prepared, and a 30 nm thick chromium oxide film (CrO X ) (first low-reflection film), a chromium film (Cr) with a thickness of 85 nm (light-shielding film), and a chromium oxide film (CrO X ) (second low-reflection film) and a light-shielding layer having a laminated structure in which they were laminated in this order.

[0127] In the fabrication of mask blanks, the light-shielding layer was formed by sputtering a chromium oxide film (first low-reflection film), a chromium film (light-shielding film), and a chromium oxide film (second low-reflection film) on the surface of synthetic quartz glass in this order. The chromium oxide film (first low-reflection film), chromium film (light-shielding film), and chromium oxide film (second low-reflection film) were deposited separately using a sputtering system with different gases. The chromium oxide film (first low-reflection film) and the chromium oxide film (second low-reflection film) were deposited by reactive sputtering in a vacuum environment, with a Cr target installed in a vacuum chamber and O, N, and CO gases introduced. The deposition conditions for the chromium oxide film (first low-reflection film) were set to a higher O gas ratio than those for the deposition of low-reflection films in the light-shielding patterns of typical binary masks. The deposition conditions for the chromium oxide film (second low-reflection film) were the same as those for the low-reflection film in the light-shielding pattern of a general binary mask, and the deposition conditions for the chromium film (light-shielding film) were the same as those for the chromium film in the light-shielding pattern of a general binary mask.

[0128] Next, a resist pattern of a desired shape was formed on the surface of the light-shielding layer, and the light-shielding layer was processed by wet etching using the resist pattern as a mask to form a light-shielding pattern having a width of 0.1 μm or more and less than 10.0 μm, including a 3.0 μm-wide light-shielding pattern from the light-shielding layer, thereby producing a large-sized photomask.

[0129] [Example A2] First, a mask blank was prepared comprising a precisely polished synthetic quartz glass (light-transmitting substrate) measuring 700 mm x 800 mm x 8 mm in length, width, and thickness, and a 180 nm-thick light-shielding layer having a layered structure in which a chromium oxide film (first low-reflection film), a chromium film (light-shielding film), and a chromium oxide film (second low-reflection film) were layered in that order on the surface of the synthetic quartz glass.

[0130] In the fabrication of mask blanks, the light-shielding layer was formed by sputtering a chromium oxide film (first low-reflection film), a chromium film (light-shielding film), and a chromium oxide film (second low-reflection film) on the surface of synthetic quartz glass in this order. The chromium oxide film (first low-reflection film), chromium film, and chromium oxide film (second low-reflection film) were deposited consecutively without changing the gas in the sputtering system. The chromium oxide film (first low-reflection film) and the chromium oxide film (second low-reflection film) were deposited by reactive sputtering in a vacuum environment, with a Cr target installed in a vacuum chamber and O2, N2, and CO2 gases introduced. The deposition conditions for the chromium oxide film (first low-reflection film) and the chromium oxide film (second low-reflection film) were set to a higher O2 gas ratio than those for the deposition of low-reflection films in the light-shielding patterns of typical binary masks. Furthermore, the deposition conditions for the chromium film (light-shielding film) were set to be the same as the deposition conditions for the chromium film in the light-shielding pattern of a general binary mask.

[0131] Next, a resist pattern of a desired shape was formed on the surface of the light-shielding layer, and the light-shielding layer was processed by wet etching using the resist pattern as a mask to form a light-shielding pattern having a width of 0.1 μm or more and less than 10.0 μm, including a 3.0 μm-wide light-shielding pattern from the light-shielding layer, thereby producing a large-sized photomask.

[0132] [Example A3] First, a mask blank was prepared, which included a precisely polished synthetic quartz glass (light-transmitting substrate) with dimensions of 700 mm x 800 mm x 8 mm in length, width, and film thickness, and a light-shielding layer having a layered structure on the surface of the synthetic quartz glass, in which a 30 nm thick chromium oxide film (first low-reflection film), a 110 nm thick chromium film (light-shielding film), and a 30 nm thick chromium oxide film (second low-reflection film) were layered in this order.

[0133] In the fabrication of mask blanks, the light-shielding layer was formed by sputtering a chromium oxide film (first low-reflection film), a chromium film (light-shielding film), and a chromium oxide film (second low-reflection film) on the surface of synthetic quartz glass in this order. The chromium oxide film (first low-reflection film), chromium film (light-shielding film), and chromium oxide film (second low-reflection film) were deposited separately using a sputtering system with different gases. The chromium oxide film (first low-reflection film) and the chromium oxide film (second low-reflection film) were deposited by reactive sputtering in a vacuum environment, with a Cr target installed in a vacuum chamber and O, N, and CO gases introduced. The deposition conditions for the chromium oxide film (first low-reflection film) and the chromium oxide film (second low-reflection film) were set to a higher O gas ratio than those for the deposition of low-reflection films in a conventional binary mask light-shielding pattern. Furthermore, the deposition conditions for the chromium film (light-shielding film) were set to a condition in which the deposition time was longer than the deposition conditions for a chromium film in a light-shielding pattern of a general binary mask.

[0134] Next, a resist pattern of a desired shape was formed on the surface of the light-shielding layer, and the light-shielding layer was processed by wet etching using the resist pattern as a mask to form a light-shielding pattern having a width of 0.1 μm or more and less than 10.0 μm, including a 3.0 μm-wide light-shielding pattern from the light-shielding layer, thereby producing a large-sized photomask.

[0135] [Comparative example A] First, a mask blank was prepared, which included a precisely polished synthetic quartz glass (light-transmitting substrate) with dimensions of 700 mm x 800 mm x 8 mm in length, width, and thickness, and a light-shielding layer having a layered structure in which an 85 nm thick chromium film (light-shielding film) and a 30 nm thick chromium oxide film (low-reflection film) were laminated in this order on the surface of the synthetic quartz glass.

[0136] In the fabrication of the mask blanks, the light-shielding layer was formed by sputtering a chromium film (light-shielding film) and a chromium oxide film (low-reflection film) in that order on the surface of synthetic quartz glass. The chromium film (light-shielding film) and the chromium oxide film (low-reflection film) were deposited separately using a sputtering system with different gases. The chromium oxide film (low-reflection film) was deposited by reactive sputtering in a vacuum environment, with a Cr target installed in a vacuum chamber and O2, N2, and CO2 gases introduced. The deposition conditions for the chromium oxide film (low-reflection film) were the same as those for the low-reflection film in the light-shielding pattern of a typical binary mask. The deposition conditions for the chromium film were the same as those for the chromium film in the light-shielding pattern of a typical binary mask.

[0137] Next, a resist pattern of a desired shape was formed on the surface of the light-shielding layer, and the light-shielding layer was processed by wet etching using the resist pattern as a mask to form a light-shielding pattern having a width of 0.1 μm or more and less than 10.0 μm, including a 3.0 μm-wide light-shielding pattern from the light-shielding layer, thereby producing a large-sized photomask.

[0138] [Evaluation results] A. Observation of the boundary structure between low-reflection film and light-shielding film The boundary structures of the low-reflection films and light-shielding films of the light-shielding patterns in Examples A1 to A3 and Comparative Example A were observed using a scanning electron microscope (SEM). As a result, the Cr content varied discontinuously at the boundaries of the light-shielding patterns in Examples 1 and 3, and the boundaries between the chromium oxide film (first low-reflection film) and the chromium film (light-shielding film) and the chromium oxide film (second low-reflection film) were clearly defined. Furthermore, the Cr content varied continuously at the boundaries of the light-shielding pattern in Example 2, and the boundaries between the chromium oxide film (first low-reflection film) and the chromium film (light-shielding film) and the chromium oxide film (second low-reflection film) were unclear. Furthermore, the Cr content varied discontinuously at the boundaries of the light-shielding pattern in Comparative Example 1, and the boundaries between the chromium film (light-shielding film) and the chromium oxide film (low-reflection film) were clearly defined.

[0139] A. Back surface reflectance and front surface reflectance of the light-shielding pattern and optical density (OD) For the large photomasks of Examples A1 to A3 and Comparative Example A, the back reflectance (reflectance of the surface facing the synthetic quartz glass) of the light-shielding pattern for light in the wavelength range of 313 nm to 436 nm, the front reflectance (reflectance of the surface facing away from the synthetic quartz glass) of the light-shielding pattern for light in the above wavelength range, and the optical density (OD) of the light-shielding pattern for light in the above wavelength range were measured.

[0140] The back surface reflectance and the front surface reflectance were measured in 1 nm increments within the above wavelength range using a spectrophotometer (Otsuka Electronics MCPD3000). The optical density (OD) was measured in 1 nm increments within the above wavelength range using a UV-visible spectrophotometer (Hitachi U-4000). Among these measurement results, the measurement results for the g-line (wavelength 436 nm), h-line (wavelength 405 nm), i-line (wavelength 365 nm), and j-line (wavelength 313 nm) are shown in Table 3 below.

[0141] The measurement conditions for the spectroscopic analyzer (Otsuka Electronics MCPD3000) are summarized in Table 1, and the measurement conditions for the ultraviolet-visible spectrophotometer (Hitachi U-4000) are summarized in Table 2.

[0142] [Table 1]

[0143] [Table 2]

[0144] C. Resist pattern properties Using the large photomasks of Examples A1 to A3 and Comparative Example A, in order to form a resist pattern of the desired shape, a 2.5 μm thick resist layer (manufactured by JSR Corporation) formed on a glass substrate was subjected to proxy exposure using an exposure stepper (reduction projection type) under the following exposure conditions.

[0145] (Exposure conditions) Exposure gap: 150 μm Light source: Ultra-high pressure mercury lamp Exposure light: Exposure light including g-line, h-line, i-line, and j-line Exposure dose: 200 mJ / cm 2

[0146] The properties of the resist patterns formed using the large photomasks of Examples A1 to A3 and Comparative Example A were evaluated by measuring the film thickness variation in the uneven parts of the resist pattern relative to the normal parts (hereinafter sometimes referred to as "uneven part film thickness variation"). Specifically, the ratio [%] of the film thickness variation in the uneven parts of Examples A1 to A3 was measured when the film thickness variation in the uneven parts of Comparative Example A was taken as 100%. The results are shown in Table 3 below.

[0147] [Table 3]

[0148] In Examples A1 to A3, as shown in Table 3 above, the back surface reflectance was 8% or less for all of the g-line, h-line, i-line, and j-line, and similar results were obtained for light of other wavelengths in the above wavelength range, although not shown in Table 3. In Examples A2 and A3, as shown in Table 3 above, the front surface reflectance was 10% or less for all of the g-line, h-line, i-line, and j-line, and similar results were obtained for light of other wavelengths in the above wavelength range, although not shown in Table 3. In Example A3, as shown in Table 3 above, the optical density (OD) was 4.5 or more for all of the g-line, h-line, i-line, and j-line, and similar results were obtained for light of other wavelengths in the above wavelength range, although not shown in Table 3. In contrast, in Comparative Example A, as shown in Table 3 above, of the g-line, h-line, i-line, and j-line, the back surface reflectance for the h-line, i-line, and j-line was greater than 8%, and the front surface reflectance for all of the g-line, h-line, i-line, and j-line was greater than 10%, and the optical density (OD) was less than 4.5.

[0149] As shown in Table 3 above, in Examples A1 to A3, the variation in film thickness in the uneven portion was more effectively suppressed than in the comparative example. In addition, in Examples A2 and A3, the variation in film thickness in the uneven portion was more effectively suppressed than in Example A1. Furthermore, in Example A3, the variation in film thickness in the uneven portion was more significantly suppressed than in Example A2.

[0150] B. Reducing foreign matter through cleaning Next, the effect of reducing foreign matter by cleaning will be described using examples and comparative examples.

[0151] [Example B1] A large photomask was produced in the same manner as in Example A3. The large-sized photomask was cut into pieces measuring 20 mm (h) × 30 mm (w) × 8 mm (d) using a glass cutter. The cut surfaces were subjected to platinum sputtering (20 mA × 12 seconds) and observed under an electron microscope. The electron microscope used was a scanning electron microscope (JEOL Ltd., JSM-6700F) with an acceleration voltage of 5.0 kV, a tilt of 0°, SEI (secondary electron downward detection) mode, a working distance of 3.2 mm to 3.3 mm (finely adjusted depending on the sample height), a single accumulation (Fine View mode), and a magnification of 100K. The measurement area was the 3.0 μm-wide light-shielding pattern. As a result of the measurement, it was found that the angle of the side surface of the first low-reflection film relative to the surface of the light-transmitting substrate was 80°. Note that this angle was obtained by drawing a straight line from the position where the side surface of the first low-reflection film meets the surface of the light-transmitting substrate to the position where the film thickness of the first low-reflection film starts to decrease, and measuring the angle between this line and the surface, as described above.

[0152] The large-sized photomask of Example B1 was washed with pure water for 300 seconds, then dried, and the number of foreign particles after washing was measured using a reflection inspection system with a sensitivity that can detect foreign particles of 1 μm or larger. This measurement was taken over an area of 690 mm × 790 mm, excluding 5 mm of each edge of the four sides of the glass substrate. The above measured values are shown in Table 4 as a percentage, with the value of Comparative Example B described below taken as 100.

[0153] [Examples B2 to B5] The etching conditions of Example B1 were changed to extend the etching time, and the angle of the side surface of the first low-reflection film relative to the surface of the light-transmitting substrate was changed to produce a large photomask with the angle shown in Table 4. The angle was measured in the same manner as in Example B1.

[0154] These large photomasks were cleaned in the same manner as in Example B1, and the number of foreign particles was measured in the same manner. The measured values are shown in Table 4 as a percentage, with the value in Comparative Example B described below being 100.

[0155] [Comparative example B] A large photomask was fabricated in the same manner as in Comparative Example A above. The angle of the side surface of the first low-reflection film relative to the surface of the light-transmitting substrate of the obtained large-sized photomask was measured in the same manner as in Example B1. The resulting large-sized photomask was cleaned in the same manner as in Example B1, and the number of foreign particles was measured in the same manner. The results are shown in Table 4, with the percentage set to 100%.

[0156] [Table 4]

[0157] As is clear from the results in Table 4, the number of foreign particles was smaller in the Examples than in the Comparative Examples. This is presumably due to the difference in affinity for foreign particles between the chromium film in the Comparative Examples and the chromium oxide film in the Examples. Furthermore, when the angle was changed, the number of foreign particles decreased as the angle became lower, and it was found that the value changed significantly especially between Example B2 and Example B3. [Explanation of symbols]

[0158] 100...Large photomask 110...Transparent substrate 120...Light blocking pattern 122...First low reflection film 124...Light-shielding film 126…Second low reflection film

Claims

[Claim 1] A large-sized photomask comprising a light-transmitting substrate and a light-shielding pattern provided on a surface of the light-transmitting substrate, the light-shielding pattern has a laminated structure in which a first low-reflection film, a light-shielding film, and a second low-reflection film are laminated in this order from the light-transmitting substrate side; A large-scale photomask, characterized in that the surface of the light-shielding pattern facing the light-transmitting substrate has a reflectance of 8% or less for light in a wavelength range of 313 nm to 436 nm.

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