KR20240046289A - Large-Sized Photomask - Google Patents

Abstract

A large photomask including a light-transmitting substrate and a light-shielding pattern provided on the surface of the light-transmitting substrate, wherein the light-shielding pattern includes a first low-reflection film, a light-shielding film, and a second low-reflection film in this order from the light-transmitting substrate side. Provided is a large-sized photomask having a laminated laminated structure, wherein the surface of the light-shielding pattern on the light-transmissive substrate side has a reflectance of 8% or less for light in a wavelength range of 313 nm to 436 nm.

Description

Large-Sized Photomask

This disclosure relates to a large-sized photomask used in the manufacture of functional elements for a display device, etc.

In the field of flat panel displays such as liquid crystal displays and organic EL displays, in recent years, higher-precision displays have been demanded, and higher pixels are in progress. Additionally, in conjunction with this, it is required to perform fine processing on functional elements for display devices, such as TFT substrates and color filters.

As a microprocessing method for manufacturing functional elements for display devices, a photolithography method using a photomask has conventionally been appropriately used. Additionally, as a photomask, a photomask having a light-shielding pattern provided on the surface of a light-transmitting substrate and having a light-transmitting area and a light-shielding area is generally used.

When such a photomask is used in an exposure device to transfer a pattern to a transfer object, if the photomask's reflectance with respect to the exposure light is high, it is susceptible to the effects of stray light caused by reflection of the exposure light through the photomask. As a result, the transfer accuracy of the pattern to the transfer object decreases. In order to suppress such problems, technology is being adopted to reduce the reflectance of the photomask with respect to the exposure light. As such a technique, for example, Patent Document 1 and the like describe the structure of a photomask in which an anti-reflection film is provided on the surface side of a light-shielding pattern.

Meanwhile, manufacturing technology for flat panel displays is evolving every year as resolution becomes more precise. In line with this, panel manufacturers are also developing technologies to form finer patterns with high precision. However, in recent years, in the field of exposure technology for transferring patterns to a transfer object, in order to form finer patterns with high precision, highly sensitive resists have been used. There is a tendency to use . Figure 11 is a graph comparing the variation in transfer line width shift with respect to exposure dose between an existing low-sensitivity resist and a high-sensitivity resist used in recent years. As shown in FIG. 11, compared to a low-sensitivity resist, a high-sensitivity resist requires less exposure amount for curing, and the variation in transfer linewidth shift at the stage of low exposure amount is large.

For this reason, along with the tendency to use highly sensitive resists, weak stray light, whose influence would have been negligible conventionally, affects the resist layer during exposure, causing unevenness and dimensional changes in the pattern transferred to the transfer object. A problem is occurring.

Additionally, in recent years, when forming a large-area pattern with high precision, the energy of the exposure light irradiated to the resist layer is insufficient in the exposure light including the g-line, h-line, or i-line. It is required to use exposure light containing light of a plurality of wavelengths such as line and i-line, and in particular, it is required to use exposure light containing j-line, which has high energy among these lights. On the other hand, when these exposure lights are used, the change in the resist layer during light exposure increases, so the influence of the above-mentioned weak stray light on the resist layer becomes greater, and the above-mentioned problems become more noticeable.

On the other hand, in the configuration described in Patent Document 1, etc., the intensity of stray light generated due to reflection of the exposure light on the photomask during exposure could not be sufficiently reduced, so the pattern transferred to the transfer object It was not possible to suppress the occurrence of unevenness or dimensional changes.

Japanese Patent No. 4451391 Publication

The present disclosure was made in consideration of the above problems, and its main purpose is to provide a large-sized photomask that can suppress the occurrence of unevenness or dimensional variation in the pattern transferred to the transfer object.

In order to solve the above problems, the present disclosure is a large-sized photomask including a light-transmitting substrate and a light-shielding pattern provided on the surface of the light-transmitting substrate, wherein the light-shielding pattern includes a first low-reflection film, a light-shielding film, and a second low-reflection film. The reflective film has a laminated structure in which the reflective film is laminated in this order from the translucent substrate side, and the surface of the light-shielding pattern on the translucent substrate side has a reflectance of 8% or less for light in a wavelength range of 313 nm to 436 nm. It provides a large photomask that

According to the present disclosure, it is possible to suppress the occurrence of unevenness or dimensional variation in the pattern transferred to the transfer object.

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

Furthermore, 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.

Additionally, 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.

Furthermore, in the above invention, it is preferable that the side inclination angle of the light-shielding film with respect to the light-transmitting substrate is 80 degrees or more and 90 degrees or less. This is because the influence of reflected light from exposure light irradiated on the side surface of the light-shielding film can be suppressed.

Furthermore, 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 translucent substrate with respect to the side surface of the light-shielding film.

In particular, both the side surface of the first low-reflection film and the side surface of the second low-reflection film protrude in a direction parallel to the surface of the translucent substrate with respect to the side surface of the light-shielding film, and the side surface of the first low-reflection film It is preferable that the side of the second low-reflection film protrudes in a direction parallel to the surface of the translucent substrate rather than the side surface of the second low-reflection film.

In addition, at least the side surface of the first low-reflection film protrudes in a direction parallel to the surface of the translucent substrate with respect to the side surface of the light-shielding film, and the angle of the side surface of the first low-reflection film with respect to the surface of the translucent substrate is It is preferable that it is 56° or less. This is because foreign matter can be easily removed by washing, and the amount of existing foreign matter can be reduced.

Additionally, in the above invention, it is preferable that the side surface of the light-shielding film is concave.

In the above invention, it is preferable that it further has a split pattern used for split exposure, and that the split pattern is the light-shielding pattern.

In the present disclosure, it is effective in suppressing the occurrence of unevenness or dimensional variation in the pattern transferred to the transfer object.

1 is a schematic cross-sectional view showing an example of a large-sized photomask of 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 object by exposure using the large photomask shown in FIG. 1.
FIG. 3 is an enlarged view of the area within the dashed line frame shown in FIG. 1 with the top and bottom of the drawing reversed.
FIG. 4 is a schematic cross-sectional view showing the area corresponding to FIG. 3 in a large photomask of the prior art.
FIG. 5 is a schematic cross-sectional view showing a region corresponding to FIG. 3 in another example of a large-sized photomask of the present disclosure.
FIG. 6 is a schematic cross-sectional view showing the area corresponding to FIG. 3 in another example of the large-sized photomask of the present disclosure.
FIG. 7 is a schematic cross-sectional view showing the area corresponding to FIG. 3 in another example of the large-sized photomask of the present disclosure.
8 is a schematic plan view showing another example of a large-sized photomask of the present disclosure.
FIG. 9 is a schematic plan view showing a pattern transfer body manufactured as a transfer object using the large photomask shown in FIG. 8.
FIG. 10 is a schematic cross-sectional view showing part of the manufacturing process of the patterned transfer body shown in FIG. 9.
Figure 11 is a graph comparing the variation in transfer line width shift with respect to exposure dose between an existing low-sensitivity resist and a high-sensitivity resist used in recent years.
FIG. 12 is a schematic cross-sectional view showing the area corresponding to FIG. 3 in another example of the large-sized photomask of the present disclosure.

Hereinafter, the large-sized photomask of the present disclosure will be described in detail.

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

An example of a large photomask of the present disclosure will be described with reference to the drawings. 1 is a schematic cross-sectional view showing an example of a large-sized photomask of the present disclosure. Additionally, FIG. 2 is a schematic cross-sectional view showing a process of transferring a pattern to a resist layer of a transfer object by exposure using the large photomask shown in FIG. 1.

As shown in FIG. 1, the large-sized photomask 100 includes a translucent substrate 110 and a light-shielding pattern 120 provided on the surface 110a of the translucent substrate 110. The light-shielding pattern 120 has a stacked structure in which the first low-reflection film 122, the light-shielding film 124, and the second low-reflection film 126 are stacked in this order from the translucent substrate 110 side. The reflectance of the surface 120a of the light-shielding pattern 120 on the transmissive substrate 110 side is 8% or less for any light in the wavelength range of 313 nm to 436 nm.

For this reason, as shown in FIG. 2, exposure light containing light in any of the above-mentioned wavelength ranges is emitted from a light source (UV lamp) using a large photomask 100, so that the base body 210 is exposed to light. When transferring a pattern to the transfer target 200 on which the resist layer 220 is formed, the exposure light is applied to the surface 120a of the light-shielding pattern 120 on the transmissive substrate 110 side and the exposure shielding plate 300. By reducing the intensity of stray light generated by multiple reflections alternately between the surface 300a, the translucent substrate 110, and the interface 112 of air (not shown), etc., the exposure shield plate 300 ), the intensity of stray light La to be irradiated to the resist layer 220 in the shielding area where irradiation of the exposure light is blocked can be reduced to, for example, less than 0.3% of the exposure illuminance. As a result, it is possible to suppress unevenness or dimensional variation in the pattern transferred to the resist layer 220 in the shielding area.

Therefore, according to the present disclosure, during exposure using exposure light containing light in any of the above wavelength ranges, stray light generated due to reflection of the exposure light on the surface of the light-shielding pattern on the translucent substrate side is prevented. By reducing the intensity, it is possible to suppress the occurrence of unevenness or dimensional variation in the pattern transferred to the transfer object.

Additionally, in recent years, in the manufacture of flat panel displays, when forming large-area patterns with high precision, g-lines (wavelength 436 nm), h-lines (wavelength 405 nm), or i-lines (wavelength 365 nm) have been used. As for the exposure light included, the energy of the exposure light irradiated to the resist layer may be insufficient. For this reason, it is required to use exposure light containing light of a plurality of wavelengths such as g-line, h-line, i-line, etc. In particular, among these lights, exposure light containing j-line (wavelength 313 nm), which has high energy, is required. It is required to use .

On the other hand, the change in the resist layer when sensitized by exposure light containing light of multiple wavelengths is greater than that by exposure light of a single wavelength, and in particular, the change in the resist layer when sensitized by exposure light containing j-line is greater. It becomes bigger. For this reason, when using exposure light containing light of a plurality of wavelengths, especially exposure light containing j-line, the influence of weak stray light on the resist becomes greater, so that the pattern transferred to the transfer object may be uneven, etc. This problem becomes more noticeable. On the other hand, in the large photomask 100 shown in FIG. 1, the above-mentioned reflectance is 8% or less for any light in the wavelength range, so any of the g-line, h-line, i-line, and j-line Also, the reflectance of the surface 120a of the light-shielding pattern 120 on the light-transmitting substrate 110 side can be reduced to 8% or less.

Therefore, according to the present disclosure, in the case of exposure using exposure light containing light of a plurality of wavelengths such as g-line, h-line, i-line, etc., and especially exposure light containing j-line, transfer to the transfer object is carried out. The occurrence of unevenness in the pattern can be significantly suppressed.

1. Shading pattern

The light-shielding pattern is a light-shielding pattern provided on the surface of the translucent substrate, and has a stacked structure in which the first low-reflection film, the light-shielding film, and the second low-reflection film are stacked in this order from the translucent substrate side, The surface of the light-shielding pattern on the translucent substrate side has a reflectance of 8% or less for light in a wavelength range of 313 nm to 436 nm.

(1) Reflectance of light in the wavelength range of 313 nm to 436 nm

The surface of the light-shielding pattern on the translucent substrate side has a reflectance of 8% or less for light in the wavelength range of 313 nm to 436 nm. That is, for any light in the wavelength range, the reflectance of the light-transmitting substrate side of the light-shielding pattern is 8% or less.

The surface of the light-shielding pattern on the light-transmitting substrate side is not particularly limited as long as it has a reflectance of 8% or less for light in the wavelength range, but especially, it has a reflectance of 5% or less for light in the wavelength range of 365 nm to 436 nm. desirable. During exposure using exposure light containing any light in the wavelength range of 365 nm to 436 nm, 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 is because the intensity of the stray light can be reduced from the level of the boundary line where the resist layer of the transfer object is sensitive to light to a level that does not completely affect it. In addition, it is preferable that the reflectance of light in the wavelength range of 313 nm to 365 nm is 5% or less. This is because the same effect is obtained during exposure using exposure light containing light in a wider wavelength range. More specifically, the same applies not only to current exposure devices and resists that use exposure light in the wavelength range of 365 nm to 436 nm, but also to other exposure devices and resists that use exposure light in the wavelength range of 313 nm to 365 nm. This is because the effect is obtained.

Here, in the present disclosure, as a method of measuring the reflectance of the light-transmitting substrate side surface of the light-shielding pattern, a device (Otsuka Electronics MCPD) using a photodiode array as a detector can be used.

The surface of the light-shielding pattern opposite to the translucent substrate preferably has a reflectance of 10% or less for light in the wavelength range of 313 nm to 436 nm. That is, for any light in the wavelength range, it is preferable that the reflectance of the surface of the light-shielding pattern opposite to the translucent substrate is 10% or less.

Additionally, the method of measuring the reflectance of the surface of the light-shielding pattern opposite to the translucent substrate is the same as that of the reflectance of the surface of the light-shielding pattern on the side of the translucent substrate.

In the large photomask 100 shown in FIG. 1, the reflectance of the surface 120b of the light blocking pattern 120 opposite to the translucent substrate 110 is, for any light in the wavelength range of 313 nm to 436 nm, It is 10% or less. For this reason, as shown in FIG. 2, a resist layer 220 is formed on the substrate 210 by exposure using a large photomask 100 and exposure light containing light in any of the above wavelength ranges. When transferring a pattern to the formed transfer target 200, the exposure light is directed to the surface 120b of the light-shielding pattern 120 on the opposite side to the translucent substrate 110, air (not shown), and the resist layer 220. ) By reducing the intensity of stray light generated by multiple reflections alternately between the interface 212 of the resist layer 220 and the interface 214 of the substrate 210, etc., the light-shielding pattern 120 is originally formed. The intensity of stray light Lb to be irradiated to the resist layer 220, where irradiation of the exposure light is blocked by the edge portion of , can be reduced to, for example, less than 2.0% of the exposure illuminance. As a result, it is possible to suppress the occurrence of dimensional variations in the pattern transferred to the resist layer 220 at the edge portion.

Therefore, it is preferable that the reflectance of light in the above wavelength range is 10% or less. During exposure using exposure light containing light in any of the wavelength ranges, the intensity of stray light generated due to reflection of the exposure light on the surface of the light-shielding pattern opposite to the translucent substrate is reduced, This is because it can effectively suppress dimensional changes in the pattern transferred to the transfer object. Among them, during exposure using exposure light containing light of a plurality of wavelengths such as g-line, h-line, i-line, etc., and especially exposure light containing j-line, changes in dimensions of the pattern transferred to the transfer object, etc. This is because this occurrence can be suppressed more significantly.

In addition, 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, and in particular, has a reflectance of 5% for light in the wavelength range of 365 nm to 436 nm. It is preferable that it is below. 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. . As a result, the intensity of the stray light is changed from the level of the boundary line where the resist layer is light-sensitive to the extent that a change in size occurs in the pattern transferred to the resist layer of the transfer object at the edge portion of the light-shielding pattern. This is because it can be reduced to a level where it does not occur completely. In addition, it is preferable that the reflectance of light in the wavelength range of 313 nm to 365 nm is 5% or less. This is because the same effect is obtained during exposure using exposure light containing light in a wider wavelength range. More specifically, the same applies not only to current exposure devices and resists that use exposure light in the wavelength range of 365 nm to 436 nm, but also to other exposure devices and resists that use exposure light in the wavelength range of 313 nm to 365 nm. This is because the effect is obtained.

(2) 1st low-reflection membrane

The first low-reflection film is provided on the side of the translucent substrate in the stacked structure of the light-shielding pattern, and has a reflectance of the light-shielding pattern on the side of the translucent substrate to light in the wavelength range of 313 nm to 436 nm of 8% or less. It is a membrane that realizes the function of reducing oxidation.

When the light-shielding pattern has the first low-reflection film, when light in the wavelength range is irradiated to the surface of the light-shielding pattern on the translucent substrate side, the light is reflected from the surface of the first low-reflection film on the translucent substrate side. Light, light reflected at the internal interface of the first low-reflective film, and light reflected at the boundary between the first low-reflective film and the light-shielding film weaken each other due to interference. As a result, the reflectance of the light-shielding pattern on the light-transmitting substrate side with respect to light in the wavelength range can be reduced to 8% or less.

As described above, when exposure light containing light of a plurality of wavelengths such as g-line, h-line, i-line, etc., and especially exposure light containing j-line is used, the influence of weak stray light on the resist As this becomes larger, the problem of unevenness in the pattern transferred to the transfer object becomes more noticeable. On the other hand, in order to solve this problem, it is difficult to form a film that realizes the function of reducing the reflectance of the light-shielding pattern for light in the wavelength region to 8% or less on the light-transmitting substrate side surface. In the present disclosure, despite such circumstances, it is possible to form a film that realizes the function of reducing the reflectance of light in the wavelength range on the side of the translucent substrate to 8% or less.

a. 1st low-reflection membrane

The film thickness of the first low-reflection film is not particularly limited as long as it is possible to realize the function of reducing the reflectance of the light-shielding pattern for light in the wavelength range on the side of the light-transmitting substrate to 8% or less, but is 10 nm to 50 nm. A film thickness within the range of nm is preferable. This is because if it is too thin, the function of reducing the reflectance is reduced, and if it is too thick, it becomes difficult to process the light-shielding pattern with high precision.

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 light-shielding pattern for light in the wavelength range on the side of the light-transmitting substrate to 8% or less, for example, chromium oxide ( _CrO Examples include molybdenum silicide oxide (MoSiO) and molybdenum silicide oxynitride (MoSiON). Among them, chromium oxide _{( CrO}

b. Formation method

Examples of methods for forming the first low-reflection film include sputtering, vacuum deposition, and ion plating. More specifically, for example, there is a method of mounting a Cr target in a vacuum chamber, introducing O ₂ , N ₂ , and CO ₂ gas, and forming a film by reactive sputtering in a vacuum environment.

In addition, in this method, the ratio of O ₂ gas is increased compared to when forming a low-reflection film in the light-shielding pattern of a general binary mask, so that the light-shielding pattern has a wavelength range of 313 nm to 436 nm on the surface of the translucent substrate. Reduce the reflectance to light to 8% or less.

(3) Second low-reflection membrane

The second low-reflection film is provided on a side opposite to the translucent substrate in the stacked structure of the light-shielding pattern, and has a reflectance for light in a wavelength range of 313 nm to 436 nm on the side of the light-shielding pattern opposite to the translucent substrate. It is a membrane that realizes the function of reducing .

When the light-shielding pattern has the second low-reflection film, when light in the wavelength range is incident on the surface of the light-shielding pattern opposite to the translucent substrate, the second low-reflection film is on the side opposite to the translucent substrate. The light reflected from the surface, the light reflected from the internal interface of the second low-reflection film, and the light reflected from the boundary between the second low-reflection film and the light-shielding film weaken each other due to interference. As a result, the reflectance of light in the wavelength range on the side of the light-shielding pattern opposite to the translucent substrate can be reduced.

a. 2nd low-reflection desert

The second low-reflection film is not particularly limited as long as it is a film that realizes the function of reducing the reflectance of light in the wavelength range of 313 nm to 436 nm on the surface opposite to the light-transmitting substrate of the light-shielding pattern. A film that realizes the function of reducing the reflectance of light in the wavelength range of 313 nm to 436 nm to 10% or less is desirable.

As described above, when exposure light containing light of a plurality of wavelengths such as g-line, h-line, i-line, etc., and especially exposure light containing j-line is used, the influence of weak stray light on the resist As this becomes larger, problems such as dimensional variations occurring in the pattern transferred to the transfer object become more noticeable. On the other hand, in order to effectively solve this problem, it is difficult to form an anti-reflection film that realizes the function of reducing the reflectance of light in the wavelength region to 10% or less on the side of the light-shielding pattern opposite to the translucent substrate. . In the present disclosure, despite such circumstances, it is possible to form a film that realizes the function of reducing the reflectance of light in the wavelength range on the opposite surface to 10% or less.

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 light in the wavelength region on the side of the light-shielding pattern opposite to the translucent substrate, but is in the range of 10 nm to 50 nm. A film thickness that is within the range is desirable. This is because if it is too thin, the function of reducing the reflectance is reduced, and if it is too thick, it becomes difficult to process the light-shielding pattern with high precision.

Since the material of the second low-reflection film is the same as that of the first low-reflection film, description here is omitted.

b. Formation method

A method of forming the second low-reflection film that reduces the reflectance of the light in the wavelength range of 313 nm to 436 nm on the surface of the light-shielding pattern opposite to the translucent substrate to 10% or less includes forming the first low-reflection film. Since it is the same as the method, the explanation here is omitted.

(4) Light-blocking membrane

The light-shielding film is a film having light-shielding properties provided between the first low-reflection film and the second low-reflection film in the laminated structure of the light-shielding pattern.

a. light blocking membrane

The thickness of the light-shielding film is not particularly limited, but is preferably within the range of 80 nm to 180 nm. This is 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.

The material of the light-shielding film is not particularly limited as long as it has light-shielding properties, and examples include chromium (Cr), chromium oxynitride (CrON), chromium nitride (CrN), molybdenum silicide oxide (MoSiO), and molybdenum silicide oxynitride. (MoSiON), tantalum oxide (TaO), and tantalum silicide oxide (TaSiO). Among them, chromium (Cr) is preferable.

b. Method of forming light-shielding film

Examples of methods for forming the light-shielding film include sputtering, vacuum deposition, and ion plating.

In addition, as a method of forming the light-shielding film in which the optical density (OD) of the light-shielding pattern for light in the wavelength range is 4.5 or more, for example, a method of increasing the time for forming the light-shielding film than usual or the number of film-forming scans A method of increasing .

(5) Shading 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. That is, for any light in the above wavelength range, it is preferable that the optical density (OD) is 4.5 or more.

Here, in the present disclosure, an ultraviolet/visible spectrophotometer (Hitachi U-4000) can be used in the method of measuring optical density (OD) for light in the above wavelength region.

In the large photomask 100 shown in FIG. 1, the optical density (OD) of the light blocking pattern 120 for light in the wavelength range of 313 nm to 436 nm is 4.5 or more. That is, the optical density (OD) of the light blocking pattern 120 is 4.5 or more for any light in the relevant wavelength range. For this reason, as shown in FIG. 2, a resist layer 220 is formed on the substrate 210 by exposure using a large photomask 100 and exposure light containing light in any of the above wavelength ranges. When transferring a pattern to the formed transfer target 200, the intensity of the transmitted light Lc through which the exposure light passes through the light-shielding pattern 120 can be reduced to, for example, 0.001% or less of the exposure illuminance. As a result, it is possible to suppress the occurrence of unevenness in the pattern transferred to the resist layer 220.

Therefore, it is preferable that the optical density (OD) is 4.5 or more. During exposure using exposure light containing light in any of the above wavelength ranges, the exposure light reduces the intensity of transmitted light that passes through the light-shielding pattern, thereby effectively preventing unevenness, etc. from occurring in the pattern transferred to the transfer object. Because it can be suppressed. Among them, during exposure using exposure light containing light of a plurality of wavelengths such as g-line, h-line, i-line, etc., especially exposure light including j-line, unevenness, etc., occurs in the pattern transferred to the transfer object. This is because it can be effectively suppressed.

Additionally, in general, it is undesirable to increase the optical density (OD) of the light-shielding pattern in a photomask because the light-shielding pattern becomes thick and it becomes difficult to process it with high precision. This tendency is particularly notable for photomasks used in the manufacture of semiconductor integrated circuits.

b. size

(a) width

Examples of the width of the light-shielding pattern include a width of 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 to the submicron order.

Here, the width of the light-shielding pattern is defined as the dimension in the short direction of the shape when viewed in plan. In addition, the width whose dimensions are controlled to the submicron order means a width whose dimensions are controlled in units of 0.1 ㎛, for example, a width of 0.1 ㎛ or more and less than 1.0 ㎛.

(b) Film thickness

The overall film thickness of the light-shielding pattern is not particularly limited, but is preferably within the range of 100 nm to 250 nm. This is 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.

c. cross section shape

The light-shielding pattern preferably has an optical density (OD) of 4.5 or more for light in the wavelength range and has a desired cross-sectional shape. Hereinafter, the preferred cross-sectional shape of the light-shielding pattern will be described.

FIG. 3 is an enlarged view showing the area within the dashed line frame shown in FIG. 1 with the top and bottom of the drawing reversed. As shown in FIG. 3, in the large photomask 100 shown in FIG. 1, the optical density (OD) of the light blocking pattern 120 for light in the wavelength range of 313 nm to 436 nm is 4.5 or more. there is. In the opening 120c of the light-shielding pattern 120, 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. Meanwhile, FIG. 4 is a schematic cross-sectional view showing the area corresponding to FIG. 3 in a large-sized photomask of the prior art. As shown in FIG. 4, in the large-sized photomask 100 of the prior art, the inclination angle α of the side surface 124a of the light-shielding film 124 with respect to the light-transmitting substrate 110 is less than 80 degrees.

As shown in FIG. 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, the inclination angle as shown in FIG. 4 Unlike the case where α is less than 80 degrees, exposure light (stray light) is irradiated to the side surface 124a of the light-shielding film 124 from the oblique direction on the light source side during exposure to transfer the pattern to the resist layer of the transfer object. The possibility that the reflected light is guided toward the opening 120c of the light blocking pattern 120 increases. Accordingly, it is possible to suppress the reflected light from being irradiated to the resist layer where irradiation of the exposure light is blocked by the edge portion of the light blocking pattern 120 . As a result, it is possible to suppress the occurrence of dimensional fluctuations in the pattern transferred to the resist layer at the edge portion.

Therefore, the light-shielding pattern having an optical density (OD) for light in the wavelength range of 4.5 or more is one in which the side inclination angle of the light-shielding film with respect to the light-transmitting substrate is 80 degrees or more and 90 degrees or less, as shown in FIG. desirable. In order to set the optical density (OD) to 4.5 or more, the light-shielding pattern becomes a thick film, so that although the amount of reflected light of the exposure light irradiated to the side surface of the light-shielding film from the oblique direction of the light source increases, the amount of reflected light increases, and the effect of the reflected light is reduced. This is because it is possible to suppress the occurrence of dimensional fluctuations in the pattern transferred to the transfer object.

In addition, the side inclination angle of the light-shielding film with respect to the light-transmitting substrate means the inclination angle of the tangent of the edge of the side of the light-shielding film on the side of the light-transmitting substrate, as indicated by α in FIG. 3.

5 to 7 are schematic cross-sectional views each showing the area corresponding to FIG. 3 in another example of the large-sized photomask of the present disclosure.

In the large-sized photomask 100 shown in FIG. 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 opening 120c of the light-shielding pattern 120, the side surface 124a of the light-shielding film 124 is a plane perpendicular to the light-transmitting substrate 110, and the side surface 122a of the first low-reflection film 122 is And the side surface 126a of the second low-reflection film 126 protrudes by a length L1 in a direction parallel to the light-transmissive substrate 110 with respect to the side surface 124a of the light-shielding film 124.

Additionally, in the large-sized photomask 100 shown in FIG. 6, 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 opening 120c of the light-shielding pattern 120, the side surface 124a of the light-shielding film 124 is a concave surface composed of a plurality of planes, and the side surface 122a of the first low-reflection film 122 ) and the side surface 126a of the second low-reflection film 126 protrudes in a direction parallel to the light-transmissive substrate 110 with respect to the side surface 124a of the light-shielding film 124 and is furthest from the opening 120c. It protrudes by a length L2 from the position of the side surface 124a of the light-shielding film 124. The side surface 124a of the light-shielding film 124 is narrowed 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 furthest from the opening 120c.

Additionally, in the large-sized photomask 100 shown in FIG. 7, 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 opening 120c of the light-shielding pattern 120, the side surface 124a of the light-shielding film 124 has a concave curved surface. The side surface 124a of the light-shielding film 124 is narrowed 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 furthest from the opening 120c.

In the large photomask 100 shown in FIGS. 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 are formed by a light-shielding film 124. It protrudes in a direction parallel to the surface 110a of the light-transmitting substrate 110 with respect to the side surface 124a. For this reason, during exposure to transfer a pattern to the resist layer of the transfer object, the exposure light (stray light) irradiated to the side surface 124a of the light-shielding film 124 from the oblique direction on the light source side is the first low-reflection film ( After the intensity is relaxed by 122), the side surface 124a of the light-shielding film 124 is irradiated. Additionally, the intensity of the reflected light of the exposure light irradiated to the side surface 124a of the light-shielding film 124 is reduced by the second low-reflection film 126 and then irradiated to the resist layer. Therefore, the intensity when the exposure light irradiated to the side surface 124a of the light-shielding film 124 from the oblique direction on the light source side is irradiated to the resist layer is determined by the first low-reflection film 122 and the second low-reflection film 126. It can be suppressed by.

Accordingly, the light-shielding pattern having an optical density (OD) for light in the wavelength range of 4.5 or more, as shown in FIGS. 5 and 6, has a side surface of the first low-reflection film or a side surface of the second low-reflection film, It is preferable that the side surface of the light-shielding film protrudes in a direction parallel to the surface of the light-transmitting substrate. In order to set the optical density (OD) to 4.5 or more, the light-shielding pattern becomes a thick film, so that although the amount of reflected light of the exposure light irradiated onto the side surface of the light-shielding film from the oblique direction of the light source increases, the amount of reflected light increases, and the effect of the reflected light is reduced. This is because the occurrence of unevenness, etc. in the pattern transferred to the transfer object can be suppressed.

In addition, 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 with respect to the side surface of the light-shielding film, and one of these sides protrudes. There is no particular limitation as long as it is, but it is preferable that both sides of these sides protrude.

In addition, 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-transmissive substrate with respect to the side surface of the light-shielding film, as shown in FIGS. 5 and 6, L1 and It is preferable that the protrusion length as indicated by L2 is at least 1/2 of the film thickness of the light-shielding film. This is because the occurrence of unevenness in the pattern transferred to the transfer object due to the influence of the reflected light can be effectively suppressed.

In addition, the protrusion length is such that the side surface of the first low-reflection film or the side surface of the second low-reflection film extends from the position furthest from the opening of the light-shielding pattern on the concave side surface of the light-shielding film to the surface of the light-transmitting substrate. It refers to the length that protrudes in a parallel direction.

In addition, 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 protrudes in a direction parallel to the surface of the translucent substrate with respect to the side surface of the light-shielding film. .

That is, in general, metal films such as chromium have higher polarity than metal oxide films such as chromium oxide, so foreign substances tend to easily adhere to them. Therefore, when the light-shielding film is chrome, if a side surface of the light-shielding film protrudes in a direction parallel to the surface of the light-transmitting substrate with respect to the side surface of the first low-reflection film or the side surface of the second low-reflection film, the difference This is because the possibility of foreign matter adhering to the photosensitive film increases, making removal of the foreign matter difficult during subsequent cleaning.

From the viewpoint of adhesion of such foreign substances, it is preferable if 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 translucent substrate with respect to the side surface of the light-shielding film, especially It is desirable that both sides of these sides protrude.

In the present disclosure, the order of the side surfaces protruding in a direction parallel to the surface of the translucent substrate is that the side surface of the first low-reflection film is the most protruding, followed by the side surface of the second low-reflection film and the side surface of the light-shielding film. desirable. When foreign matter is present near the side surface of these laminates, since the side surface of the first low-reflection film protrudes the most, the area in which the foreign matter contacts the metal oxide film is large, so it is easy to come into contact, and as a result, the foreign matter is peeled off. This is because it becomes easier.

Meanwhile, in the present disclosure, at least the side surface of the first low-reflection film protrudes in a direction parallel to the surface of the translucent substrate with respect to the side surface of the light-shielding film, and the translucent substrate on the side surface of the first low-reflection film It is desirable that the angle with respect to the surface is 56° or less.

Fig. 12 shows a part of an example of a large photomask of this type. In the large 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 are the side surfaces of the light-shielding film 124 ( With respect to 124a), it protrudes in a direction parallel to the surface 110a of the light-transmitting substrate 110. Additionally, the angle α formed between the side surface 122a of the first low-reflection film 122 and the surface 110a of the translucent substrate 110 is less than or equal to 56°.

As described above, since the angle of the side surface of the first low-reflection film with respect to the surface of the translucent substrate is 56° or less, the area contacted by the cleaning fluid during cleaning can be increased even when foreign matter is attached. , cleaning can be performed efficiently, and it becomes possible to prevent defects due to the presence of foreign matter after the cleaning process.

Here, the angle of the side surface of the first low-reflective film 122 with respect to the surface of the translucent substrate is the position A where the side surface 122a of the first low-reflective film 122 and the surface 110a of the translucent substrate 110 contact, This is an angle obtained by drawing a straight line at the position B where the film thickness reduction of the first low-reflection film 122 begins and measuring the angle between this straight line and the surface 110a.

In addition, the fact that the side surface 122a of the first low-reflection film 122 protrudes with respect to the side surface 124a of the light-shielding film 124 means that the film thickness of the first low-reflection film 122 is reduced. This means that the position B where is started protrudes in a direction parallel to the surface 110a of the light-transmitting substrate 110 with respect to the side surface 124a of the light-shielding film 124.

In the present disclosure, the angle of the side surface of the first low-reflection film with respect to the surface of the translucent substrate is preferably 56° or less, and more preferably 40° or less. This is because cleaning can be performed more efficiently. In addition, it is preferable that the angle is small, but from the viewpoint of manufacturing that actual manufacturing is difficult, it is preferable that it is 20 degrees or more.

In the present disclosure, it is preferable that the side surface of the second low-reflection film also protrudes in a direction parallel to the surface of the translucent substrate rather than the side surface of the light-shielding film. This is because it can reduce the adhesion of foreign substances to the side of the light-shielding film, where removal of foreign substances by washing may be difficult due to the influence of adhesion to foreign substances.

In the large photomask 100 shown in FIGS. 6 and 7, the side surface 124a of the light-shielding film 124 is concave. For this reason, during exposure to transfer a pattern to the resist layer of the transfer object, the reflected light of the exposure light (stray light) irradiated on the side 124a of the light-shielding film 124 from the oblique direction on the light source side is either on the light source side or The possibility of being guided toward the opening 120c of the light blocking pattern 120 increases. Accordingly, it is possible to suppress the reflected light from being irradiated to the resist layer where irradiation of the exposure light is blocked by the edge portion of the light blocking pattern 120 . As a result, it is possible to suppress the occurrence of dimensional fluctuations in the pattern transferred to the resist layer at the edge portion.

Therefore, as the light-shielding pattern having an optical density (OD) of 4.5 or more for light in the wavelength range, it is preferable that the side surface of the light-shielding film is concave, as shown in FIGS. 6 and 7. In order to set the optical density (OD) to 4.5 or more, the light-shielding pattern becomes a thick film, so that although the amount of reflected light of the exposure light irradiated onto the side surface of the light-shielding film from the oblique direction of the light source increases, the amount of reflected light increases, and the effect of the reflected light is reduced. This is because it is possible to suppress the occurrence of dimensional fluctuations in the pattern transferred to the transfer object.

In addition, as the light-shielding pattern in which the side surface of the light-shielding film is concave, the width of the concave portion of the side surface of the light-shielding film as indicated by W1 and W2 in FIGS. 6 and 7 is at least 1/2 of the film thickness of the light-shielding film. It is desirable. This is because the occurrence of dimensional fluctuations in the pattern transferred to the transfer object due to the influence of the reflected light can be effectively suppressed.

In addition, the width of the constriction means the width in the direction parallel to the surface of the light-transmitting substrate from the position closest to the opening of the light-shielding pattern on the side of the light-shielding film to the position furthest away from the opening of the light-shielding pattern.

d. Boundary structure of low-reflection film and light-shielding film

The boundary between the light-shielding film, the first low-reflection film, and the second low-reflection film may be a clear boundary or an unclear boundary. Since it is easy to individually control the characteristics of each film, a light-shielding pattern having the above-mentioned clear boundaries is preferable. In addition, a light-shielding pattern having the above-described indistinct boundary is preferable because the processed surface is smooth and can be easily manufactured.

The light-shielding pattern having the clear boundary can be produced by separately forming the first low-reflection film, the light-shielding film, and the second low-reflection film using a gas-replaced sputtering device. Additionally, the light-shielding pattern having the indistinct boundary can be produced by continuously forming the first low-reflection film, the light-shielding film, and the second low-reflection film without replacing the gas of the sputtering device.

e. Formation method

As a method of forming the light-shielding pattern, for example, 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 stacked in this order is formed on the surface of synthetic quartz glass. , a method of forming a resist pattern of a desired shape on the surface of the light-shielding layer, and processing the light-shielding layer by wet etching using the resist pattern as a mask.

2. Transmissive substrate

The size of the translucent substrate may be, for example, a photomask having at least one side of 350 mm or more, and may be appropriately selected according to the purpose of the large-sized photomask of the present disclosure, etc., and is not particularly limited, but is 330 mm It is preferable that it is 450 mm or more, and especially, it is preferable that it is within the range of 330 mm x 450 mm to 1,700 mm x 1,800 mm.

The film thickness of the translucent substrate can be appropriately selected depending on the material or purpose of the large-sized photomask. The film thickness of the translucent substrate is, for example, about 8 mm to 17 mm.

As the translucent substrate, a translucent substrate that has light transparency and is used in a general large-sized photomask can be used. Examples of the light-transmitting substrate include optically polished low-expansion glass (alumino borosilicate glass, borosilicate glass) and synthetic quartz glass. In the present disclosure, synthetic quartz glass is suitably used, among others. This is because the coefficient of thermal expansion is small, making it easy to manufacture large photomasks. Additionally, in the present disclosure, the above transparent resin substrate can also be used.

The light transmittance of the above-mentioned translucent substrate is not particularly limited as long as it is of the same level as that of the translucent substrate used in general large-sized photomasks, but it is preferable that the transmittance for light in the wavelength range of 313 nm to 436 nm is 80% or more, especially 85%. It is preferable that it is % or more, especially 90% or more. This is because a translucent substrate with high purity has less scattering of light passing through the material and also has a lower refractive index, thereby suppressing the generation of stray light.

3. Others

The large-sized photomask of the present disclosure is provided with the light-transmitting substrate and the light-shielding pattern, and is not particularly limited as long as the reflectance of the light-shielding pattern on the side of the light-transmitting substrate for light in the wavelength range is 8% or less, but split exposure It is preferable that it has a split pattern used for, and that the split pattern is the light-shielding pattern.

Split exposure refers to dividing the transferred area on a transfer object into a plurality of exposure areas, exposing each of the plurality of exposure areas individually using a large photomask, and applying a split pattern of the photomask to each of the plurality of exposure areas. This refers to a method of forming a continuous pattern larger than the division pattern of the photomask on the transfer object by transferring.

Such a preferable large photomask will be described with reference to the drawings. Figure 8 is a schematic plan view showing another example of a large-sized photomask of the present disclosure. FIG. 9 is a schematic plan view showing a pattern transfer body manufactured as a transfer object using the large photomask shown in FIG. 8. 10(a) to 10(b) are schematic cross-sectional views showing a part of the manufacturing process for the pattern transfer body shown in FIG. 9.

As shown in FIG. 8, the large photomask 100 is provided on the translucent substrate 110 and the surface 110a of the translucent substrate 110, and has different first division patterns 150a and second division patterns. It has a pattern 150b and a third division pattern 150c. The first split pattern 150a, the second split pattern 150b, and the third split pattern 150c each have a first low-reflection film 122, similar to the light blocking pattern 120 shown in FIG. 1, and have light blocking properties. The film 124 and the second low-reflection film 126 are the light-shielding pattern 120 having a stacked structure in which the film 124 and the second low-reflection film 126 are stacked in this order from the light-transmissive substrate 110 side. For this reason, the surface of the first split pattern 150a, the second split pattern 150b, and the third split pattern 150c on the side of the translucent substrate 110 is similar to the light-shielding pattern 120 shown in FIG. The reflectance for light in the wavelength range of 313 nm to 436 nm is 8% or less.

The pattern transfer body 200' shown in FIG. 9 uses the large photomask 100 shown in FIG. 8 to apply a first split pattern 150a to the resist layer 220 of the transfer target 200. ), the second split pattern 150b, and the third split pattern 150c are manufactured by exposure in which exposure light containing light in any of the above wavelength ranges is emitted from a light source (UV lamp).

When the pattern transfer body 200' is manufactured, first, in the first exposure, the second split pattern 150b and the third split pattern 150c are exposed to the exposure shielding plate 300 (shown in FIG. 10). By shielding, the exposure light is irradiated to the resist layer 220 through only the first split pattern 150a among the first to third split patterns. Next, in the second to sixth exposures, the third split pattern 150c and the first split pattern 150a are shielded with the exposure shielding plate 300, thereby exposing the resist layer 220 to the first to third split patterns 150c. The exposure light is irradiated only through the second split pattern 150b among the third split patterns. Next, in the seventh exposure, the first to third split patterns are formed on the resist layer 220 by shielding the first split pattern 150a and the second split pattern 150b with the exposure shielding plate 300. The exposure light is irradiated only through the third split pattern 150c among the patterns. As a result, one first resist pattern 220a to which the first division pattern 150a is transferred, five second resist patterns 220b to which the second division pattern 150b is respectively transferred, and the third division pattern 150c. ) is transferred, and one third resist pattern 220c is formed to be connected in a single direction. As a result, a single continuous resist pattern is formed.

In the second exposure described above, as shown in FIG. 10(a), similar to the process shown in FIG. 2, the exposure light is applied to the second division pattern 150b (light-shielding pattern 120). By reducing the intensity of stray light generated due to reflection from the surface 120a on the translucent substrate 110 side, the shielding area (third exposure) where irradiation of the exposure light is originally blocked by the exposure shielding plate 300 is reduced. The intensity of stray light La to be irradiated to the resist layer 220 (region) can be reduced. In addition, by reducing the intensity of stray light generated due to the exposure light being reflected from the surface 120b of the second split pattern 150b opposite to the translucent substrate 110, the second split pattern is originally The intensity of stray light Lb to be irradiated to the resist layer 220 in the second exposure area where irradiation of the exposure light is blocked by the edge portion of 150b can be reduced.

In the third exposure described above, as shown in Figure 10 (b), the intensity of stray light is reduced as in the second exposure, so that the resist layer ( The intensity of stray light Lb to be irradiated to 220) can be further reduced, and the intensity of stray light La to be irradiated to the resist layer 220 in the area where stray light Lb has been irradiated in the second exposure can be further reduced.

Therefore, according to the above-described preferred large-sized photomask, in divided exposure, when each of the plurality of exposure areas of the transfer object is individually exposed using the large-sized photomask, the exposure light is reflected from each surface of the light-shielding pattern. By irradiating stray light generated as a result to different exposure areas, the intensity of the stray light can be reduced even when multiple exposures due to the stray light occur in the resist layer. For this reason, it is possible to significantly suppress the occurrence of unevenness or dimensional variation in the pattern transferred to the transfer object.

Additionally, in divided exposure, multiple exposures may occur in areas where adjacent exposure areas are connected due to the influence of the alignment accuracy of the exposure apparatus. For this reason, when multiple exposures due to stray light further occur, the problem of unevenness or dimensional variation in the pattern transferred to the transfer object is likely to increase. For this reason, the above-described effects are more significantly obtained.

4. Manufacturing method of large photomask

The method for manufacturing a large-sized photomask of the present disclosure is not particularly limited as long as a large-sized photomask having the above-mentioned structure can be manufactured, and can be done in the same manner as a method for manufacturing a general large-sized photomask.

For example, synthetic quartz glass is prepared as a light-transmitting substrate, and 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 is provided on the surface of the synthetic quartz glass. Produce mask blanks. Next, a resist pattern of a desired shape is formed on the surface of the light-shielding layer, and the light-shielding layer is wet-etched using the resist pattern as a mask to form a light-shielding pattern from the light-shielding layer. In this way, a large photomask is produced.

Additionally, the etching solution used in the wet etching is not particularly limited as long as it is capable of processing the light-shielding layer with high precision and does not cause damage to the translucent substrate. For example, cerium ammonium nitrate solution can be used. .

5. Uses

The large-sized photomask of the present disclosure can be suitably used, for example, in a photolithography method in the production of pattern transfer bodies such as functional elements for display devices used in display devices.

Functional elements for display devices to be manufactured using the large photomask of the present disclosure include, for example, TFT substrates, substrates with metal wiring used for TFT substrates, etc., color filters, substrates with light-shielding portions used in color filters, etc. You can.

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 done in the same manner as a general manufacturing method using a large-sized photomask manufacturing method. For example, a manufacturing method including an exposure step of preparing a transfer object having a resist layer, exposing the resist layer by irradiating exposure light through a large photomask, and a development step of developing the resist layer after exposure. You can.

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 resin, phenol epoxy resin, acrylic resin, polyimide, and cycloolefin. Specifically, IP3500 (manufactured by TOK), PFI27 (manufactured by Sumitomo Chemical), ZEP7000 (manufactured by Zeon), and positive resist (manufactured by JSR). Among them, positive resist (manufactured by JSR) and the like are preferable. This is because the sensitivity is high and the effect of the present disclosure becomes significant. On the other hand, examples of negative resists include acrylic resin. Specifically, polyglycidyl methacrylate (PGMA), chemically amplified SAL601 (manufactured by Cipress), and negative resist (manufactured by JSR). Among them, negative resist (manufactured by JSR) and the like are preferable. This is because the sensitivity is high and the effect of the present disclosure becomes significant. Additionally, when a functional element for a display device manufactured using the large-sized photomask of the present disclosure uses the developed resist layer as a structural member, colorants such as pigments and dyes, and functional materials such as inorganic oxide fine particles are added to the resist layer. It may be contained.

The film thickness of the resist layer is not particularly limited, but is, for example, in the range of 10 nm to 10 μm. As for the method of forming the resist layer, since it can be done by a known method, description here is omitted.

The transfer target usually has a base for forming a resist layer. Additionally, it may have a metal layer or the like. The transfer target is appropriately selected depending on the type of functional element for the display device being manufactured.

The exposure light used in the exposure process is not particularly limited as long as it can cause the resist in the resist layer to react and includes any light in the wavelength range of 313 nm to 436 nm. As exposure light, exposure light containing light of a plurality of wavelengths such as g-line, h-line, i-line, etc. is preferable, and exposure light containing j-line is especially preferable. This is because the energy of the exposure light irradiated to the resist layer can be increased, allowing exposure to be completed in a shorter exposure time, and the occurrence of unevenness in the pattern transferred to the transfer object can be significantly suppressed. As a light source for the exposure light, for example, an ultra-high pressure mercury lamp (ultra-high pressure UV lamp) can be used.

As a method for developing the resist layer used in the above development process, a general method can be used and is not particularly limited. As a developing method, for example, a method using a developing solution can be suitably used.

Additionally, the present disclosure is not limited to the above embodiments. The above-mentioned embodiment is an example, and anything that has substantially the same structure as the technical idea described in the claims of the present disclosure and exhibits similar functions and effects is included in the technical scope of the present disclosure.

Example

A. Reflectance and optical density

First, reflectance and optical density will be explained using examples and comparative examples.

[Example A1]

First, a precision-polished synthetic quartz glass (transmissive substrate) with a length × width × film thickness of 700 mm × 800 mm × 8 mm was applied, and a chromium oxide film ( _CrO A stacked structure in which a chromium oxide film ( _CrO A mask blank having a light-shielding layer was manufactured.

In the production of the mask blank, the light-shielding layer is made of synthetic quartz using a sputtering method in the following order: chromium oxide film (first low-reflection film), chromium film (light-shielding film), and chromium oxide film (second low-reflection film). It was formed by forming a film on the surface of glass. At this time, the formation of the chromium oxide film (first low-reflection film), chromium film (light-shielding film), and chromium oxide film (second low-reflection film) was performed separately using a sputtering device with a different gas. In addition, the chromium oxide film (first low-reflection film) and the chromium oxide film (second low-reflection film) are subjected to reactive sputtering in a vacuum environment by installing a Cr target in a vacuum chamber and introducing O ₂ , N ₂ , and CO ₂ gases. The tabernacle was built by . The deposition conditions for the chromium oxide film (first low-reflection film) were conditions in which the ratio of O ₂ gas was increased compared to the deposition conditions for the low-reflection film in the light-shielding pattern of a general binary mask. In addition, the film formation conditions for the chromium oxide film (second low-reflection film) were set to the same conditions as the film formation conditions for the low-reflection film in the light-shielding pattern of a general binary mask. In addition, the film formation conditions for the chromium film (light-shielding film) were set to the same conditions as the film formation conditions for the chromium film in the light-shielding pattern of a general binary mask.

Next, a resist pattern of the 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, thereby forming a light-shielding pattern with a width of 0.1 μm or more and less than 10.0 μm from the light-shielding layer. A light blocking pattern with a width of was formed. In this way, a large photomask was produced.

[Example A2]

First, precision-polished synthetic quartz glass (light-transmitting substrate) with a length × width × film thickness of 700 mm × 800 mm × 8 mm, a chromium oxide film (first low-reflection film), a chromium film (light-shielding film), and oxide A mask blank including a light-shielding layer with a film thickness of 180 nm having a laminated structure in which a chromium film (second low-reflection film) was laminated in this order on the surface of synthetic quartz glass was produced.

In the production of the mask blank, the light-shielding layer is made of synthetic quartz using a sputtering method in the following order: chromium oxide film (first low-reflection film), chromium film (light-shielding film), and chromium oxide film (second low-reflection film). It was formed by forming a film on the surface of glass. At this time, the deposition of the chromium oxide film (first low-reflection film), the chromium film, and the chromium oxide film (second low-reflection film) were performed continuously without replacing the gas of the sputtering device. In addition, the chromium oxide film (first low-reflection film) and the chromium oxide film (second low-reflection film) are subjected to reactive sputtering in a vacuum environment by installing a Cr target in a vacuum chamber and introducing O ₂ , N ₂ , and CO ₂ gases. The tabernacle was built by . The film formation conditions for the chromium oxide film (first low-reflection film) and the chromium oxide film (second low-reflection film) were conditions in which the ratio of O ₂ gas was increased compared to the film formation conditions for the low-reflection film in the light-shielding pattern of a general binary mask. In addition, the film formation conditions for the chromium film (light-shielding film) were set to the same conditions as the film formation conditions for the chromium film in the light-shielding pattern of a general binary mask.

Next, a resist pattern of the 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, thereby forming a light-shielding pattern with a width of 0.1 μm or more and less than 10.0 μm from the light-shielding layer. A light blocking pattern with a width of was formed. In this way, a large photomask was produced.

[Example A3]

First, a precision-polished synthetic quartz glass (transmissive substrate) with a length × width × film thickness of 700 mm × 800 mm × 8 mm was applied, and a chromium oxide film (first low-reflection film) with a film thickness of 30 nm was placed on the surface of the synthetic quartz glass. ), a chromium film (light-shielding film) with a film thickness of 110 nm (light-shielding film), and a chromium oxide film (second low-reflection film) with a film thickness of 30 nm were laminated in this order to produce a mask blank having a light-shielding layer. .

In the production of the mask blank, the light-shielding layer is made of synthetic quartz using a sputtering method in the following order: chromium oxide film (first low-reflection film), chromium film (light-shielding film), and chromium oxide film (second low-reflection film). It was formed by forming a film on the surface of glass. At this time, the deposition of the chromium oxide film (first low-reflection film), the chromium film (light-shielding film), and the chromium oxide film (second low-reflection film) were each performed separately using a sputtering device with a changed gas. In addition, the chromium oxide film (first low-reflection film) and the chromium oxide film (second low-reflection film) are subjected to reactive sputtering in a vacuum environment by installing a Cr target in a vacuum chamber and introducing O ₂ , N ₂ , and CO ₂ gases. The tabernacle was built by . The film formation conditions for the chromium oxide film (first low-reflection film) and the chromium oxide film (second low-reflection film) were conditions in which the ratio of O ₂ gas was increased compared to the film formation conditions for the low-reflection film in the light-shielding pattern of a general binary mask. Additionally, the film formation conditions for the chromium film (light-shielding film) were conditions in which the film formation time was increased compared to the film formation conditions for the chromium film in the light-shielding pattern of a general binary mask.

Next, a resist pattern of the 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, thereby forming a light-shielding pattern with a width of 0.1 μm or more and less than 10.0 μm from the light-shielding layer. A light blocking pattern with a width of was formed. In this way, a large photomask was produced.

[Comparative Example A]

First, precision-polished synthetic quartz glass (light-transmitting substrate) with a length × width × film thickness of 700 mm × 800 mm × 8 mm, a chromium film (light-shielding film) with a film thickness of 85 nm on the surface of the synthetic quartz glass, and A mask blank provided with a light-shielding layer having a laminated structure in which chromium oxide films (low-reflection films) with a film thickness of 30 nm were laminated in this order was produced.

In the production of the mask blank, the light-shielding layer was formed by sequentially forming a chromium film (light-shielding film) and a chromium oxide film (low-reflection film) on the surface of synthetic quartz glass using a sputtering method. At this time, the formation of the chromium film (light-shielding film) and the chromium oxide film (low-reflection film) was performed separately using a sputtering device with a changed gas. Additionally, the chromium oxide film (low-reflection film) was formed by installing a Cr target in a vacuum chamber, introducing O ₂ , N ₂ , and CO ₂ gases, and using reactive sputtering in a vacuum environment. The film formation 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 general binary mask. In addition, the conditions for forming the chrome film were the same as those for forming the chrome film in the light-shielding pattern of a general binary mask.

Next, a resist pattern of the 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, thereby forming a light-shielding pattern with a width of 0.1 μm or more and less than 10.0 μm from the light-shielding layer. A light blocking pattern with a width of was formed. In this way, a large photomask was produced.

[Evaluation results]

go. Observation of boundary structure of low-reflection film and light-shielding film

The boundary structures of the low-reflection film and the light-shielding film of the light-shielding patterns in Examples A1 to A3 and Comparative Example A were observed using a SEM (scanning electron microscope). As a result, at the boundary of the light-shielding pattern in Examples 1 and 3, the content of Cr changes discontinuously, and the boundary between the chromium oxide film (first low-reflection film) and the chromium film (light-shielding film) and the chromium film ( The boundary between the light-shielding film) and the chromium oxide film (second low-reflection film) was clear. Additionally, at the boundary of the light-shielding pattern in Example 2, the Cr content rate changes continuously, and the boundary between the chromium oxide film (first low-reflection film) and the chromium film (light-shielding film) and the chromium film (light-shielding film) The boundary between the film) and the chromium oxide film (second low-reflection film) was unclear. Additionally, at the boundary of the light-shielding pattern in the comparative example, the Cr content changed discontinuously, and the boundary between the chromium film (light-shielding film) and the chromium oxide film (low-reflection film) was clear.

me. Back and surface reflectance and optical density (OD) of the shading pattern

For the large photomasks of Examples A1 to A3 and Comparative Example A, the reflectance of the back surface of the light-shielding pattern (reflectance of the synthetic quartz glass side) for light in the wavelength range of 313 nm to 436 nm and the reflectance for light in the wavelength range. The surface reflectance of the light-shielding pattern (reflectance of the surface opposite to the synthetic quartz glass) and the optical density (OD) of the light-shielding pattern for light in the above wavelength range were measured.

The back reflectance and the surface reflectance were measured every 1 nm in the wavelength range using a spectroscopic analyzer (Otsuka Electronics MCPD3000). In addition, the optical density (OD) was measured every 1 nm in the above wavelength range using an ultraviolet/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.

The measurement conditions of the spectrophotometer (Otsuka Electronics MCPD3000) are shown in Table 1, and the measurement conditions of the ultraviolet/visible spectrophotometer (Hitachi U-4000) are shown in Table 2.

all. Properties of resist pattern

For the purpose of forming a resist pattern of a desired shape using the large photomasks of Examples A1 to A3 and Comparative Example A, a resist layer (manufactured by JSR Corporation) with a film thickness of 2.5 μm was formed on a glass substrate, Exposure stepper type (reduced projection type) proxy exposure was performed under the following exposure conditions.

(Exposure conditions)

Exposure gap: 150㎛

Light source: ultra-high pressure mercury lamp

Exposure light: Exposure light including g-line, h-line, i-line, and j-line

Exposure dose: 200mJ/㎠

Properties of the resist pattern formed using the large photomask of Examples A1 to A3 and Comparative Example A, the film thickness variation at the top of the uneven part of the resist pattern (hereinafter sometimes referred to as the “film thickness variation of the uneven part”) ) was evaluated. Specifically, the ratio [%] of the uneven film thickness variation of Examples A1 to A3 when the uneven film thickness variation of Comparative Example A was set to 100% was measured. The results are shown in Table 3 below.

In Examples A1 to A3, as shown in Table 3 above, the back surface reflectance was 8% or less for any of the g-line, h-line, i-line, and j-line. Although not shown in Table 3, the back surface reflectance was 8% or less. The same result was obtained for light of other wavelengths in the wavelength range. In Examples A2 and A3, as shown in Table 3 above, the surface reflectance was 10% or less for any of the g-line, h-line, i-line, and j-line, and was not shown in Table 3 above. The same result was obtained for light of other wavelengths in the above wavelength range. In Example A3, as shown in Table 3 above, the optical density (OD) was 4.5 or more for any of the g-line, h-line, i-line, and j-line, and was not shown in Table 3 above. The same result was obtained for light of other wavelengths in the above wavelength range. On the other hand, in Comparative Example A, as shown in Table 3 above, among 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%. As a result, the surface reflectance became greater than 10% for any of the g-line, h-line, i-line, and j-line, and the optical density (OD) became less than 4.5.

As shown in Table 3, in Examples A1 to A3, the uneven film thickness variation was suppressed more than the comparative example. Additionally, in Examples A2 and A3, the uneven film thickness variation could be suppressed more effectively than in Example A1. Additionally, in Example A3, the uneven film thickness variation was able to be suppressed significantly more than in Example A2.

B. Reduction of foreign matter by cleaning

Next, the effect of reducing foreign substances by cleaning will be explained using examples and comparative examples.

[Example B1]

A large photomask was manufactured in the same manner as in Example A3.

The created large photomask was cut within 20 mm (h) x 30 mm (w) x 8 mm (d) using a glass cutter. The cut surface was sputtered with platinum (20 mA x 12 seconds) and observed with an electron microscope. For the electron microscope, a scanning electron microscope (JSM-6700F, manufactured by Nippon Electronics Co., Ltd.) was used, with an acceleration voltage of 5.0 kV, an inclination of 0°, and a working mode of SEI (secondary electron downward detection). The distance was set to 3.2 mm to 3.3 mm (finely adjusted depending on the height of the sample), the number of integrations was set to 1 (Fine View mode), and the observation magnification was set to ×100K. The measurement location was a portion of a light-shielding pattern with a width of 3.0 μm.

As a result of the measurement, it was obtained that the angle of the side surface of the first low-reflection film with respect to the surface of the translucent substrate was 80°. In addition, as described above, this angle is determined by drawing a straight line at the position where the side surface of the first low-reflective film contacts the surface of the translucent substrate and where the film thickness reduction of the first low-reflective film begins, and this straight line It is an angle obtained by measuring the angle of the surface.

The large photomask of Example B1 was cleaned with pure water for 300 seconds, then dried, and the number of foreign substances after cleaning was measured using a reflection test using an external inspection device with a sensitivity that can detect foreign substances larger than 1 μm. This measurement value is a value measured over an area of 690 mm x 790 mm excluding 5 mm at the ends of the four sides of the glass substrate.

The above measured values are shown in Table 4 as ratios when the value obtained in Comparative Example B described later is set to 100.

[Examples B2 to B5]

The etching conditions of Example B1 were changed in the direction of extending the etching time, and the angle of the side of the first low-reflection film with respect to the surface of the translucent substrate was changed to produce a large photomask with the angle shown in Table 4 below. Produced. The angle was measured in the same manner as in Example B1.

These large photomasks were cleaned by the same method as Example B1, and the number of foreign substances was measured in the same manner. The above measured values are shown in Table 4 as a ratio when the value obtained in Comparative Example B described later is set to 100.

[Comparative Example B]

A large photomask was manufactured in the same manner as in Comparative Example A.

For the obtained large-sized photomask, the angle of the side surface of the first low-reflection film with respect to the surface of the translucent substrate was measured by the same method as Example B1.

Additionally, the obtained large-sized photomask was cleaned by the same method as Example B1, and the number of foreign substances was measured in the same manner. The results are shown in Table 4 as 100%.

As is clear from the results in Table 4, compared to the comparative example, the number of foreign substances in the example was small. This is presumed to be due to the difference in affinity between the chromium film in the comparative example and the chromium oxide film in the example and the foreign matter.

In addition, when the angle was changed, it was found that the lower the angle, the lower the number of foreign substances, and especially between Example B2 and Example B3, the value changed significantly.

100: Large photomask
110: Light-transmitting substrate
120: Shading pattern
122: 1st low-reflection membrane
124: Light-blocking film
126: Second low-reflection membrane

Claims (7)

It is a large photomask including a light-transmitting substrate and a light-shielding pattern provided on the surface of the light-transmitting substrate,
The light-shielding pattern has a stacked structure in which a first low-reflection film, a light-shielding film, and a second low-reflection film are stacked in this order from the translucent substrate side,
A large photomask wherein the surface of the light-shielding pattern opposite to the translucent substrate has a reflectance of 5% or less for light in a wavelength range of 365 nm to 436 nm. It is a large photomask including a light-transmitting substrate and a light-shielding pattern provided on the surface of the light-transmitting substrate,
The light-shielding pattern has a stacked structure in which a first low-reflection film, a light-shielding film, and a second low-reflection film are stacked in this order from the translucent substrate side,
The surface of the light-shielding pattern on the translucent substrate side has a reflectance of 8% or less for light in a wavelength range of 313 nm to 436 nm,
The film thickness of the layered structure is 100 nm to 250 nm, and the light-shielding film has a film thickness of 80 nm to 180 nm,
The light-shielding pattern has an optical density (OD) of 3.7 or more for light with a wavelength of 436 nm,
A large photomask wherein a lateral inclination angle of the light-shielding film with respect to the light-transmitting substrate is 80° or more and 90° or less. According to paragraph 2,
The light-shielding pattern is a large photomask having an optical density (OD) of 4.4 or more for light with a wavelength of 313 nm. According to paragraph 3,
The light-shielding pattern is a large photomask having an optical density (OD) of 4.1 or more for light with a wavelength of 405 nm and an optical density (OD) of 4.4 or more for light with a wavelength of 365 nm. It is a large photomask including a light-transmitting substrate and a light-shielding pattern provided on the surface of the light-transmitting substrate,
The light-shielding pattern has a stacked structure in which a first low-reflection film, a light-shielding film, and a second low-reflection film are stacked in this order from the translucent substrate side,
At least a side surface of the first low-reflective film protrudes in a direction parallel to the surface of the translucent substrate with respect to the side surface of the light-shielding film,
In addition, a large photomask wherein the angle of the side of the first low-reflection film with respect to the surface of the translucent substrate is 56° or less. According to clause 5,
A large photomask wherein the surface of the light-shielding pattern on the translucent substrate side has a reflectance of 8% or less for light in a wavelength range of 313 nm to 436 nm. A large-sized photomask according to any one of claims 1 to 6, wherein the large-sized photomask has a split pattern used for split exposure, and the split pattern is the light-shielding pattern.