CN112119352A

CN112119352A - Large-scale photomask

Info

Publication number: CN112119352A
Application number: CN201980032507.6A
Authority: CN
Inventors: 今野冬木; 三好建也
Original assignee: Dai Nippon Printing Co Ltd
Current assignee: Dai Nippon Printing Co Ltd
Priority date: 2018-03-15
Filing date: 2019-03-14
Publication date: 2020-12-22
Also published as: JP2024001250A; KR20240046289A; TW201945832A; JPWO2019177116A1; JP7420065B2; TWI711878B; WO2019177116A1; KR20200128141A; KR102653366B1

Abstract

The present invention provides a large photomask comprising a light-transmitting substrate and a light-shielding pattern provided on a surface of the light-transmitting substrate, wherein the light-shielding pattern has a laminated structure in which a1 st low-reflection film, a light-shielding film, and a2 nd low-reflection film are laminated in this order from the light-transmitting substrate side, and the light-shielding pattern has a reflectance of light in a wavelength region of 313nm to 436nm on the light-transmitting substrate side of 8% or less.

Description

Large-scale photomask

Technical Field

The present invention relates to a large photomask used for manufacturing a functional element for a display device used in a display device.

Background

In the field of flat panel displays such as liquid crystal display devices and organic EL (Electro-Luminescence) display devices, higher definition display is desired and higher pixel count is progressing in recent years. In addition, in response to this, for example, functional elements for display devices such as a TFT (Thin Film Transistor) substrate and a color filter are required to be subjected to microfabrication.

As a microfabrication method for manufacturing a functional element for a display device, a photolithography method using a photomask is preferably employed from the past. In general, a photomask having a light-shielding pattern provided on a surface of a light-transmissive substrate and including a light-transmissive region and a light-shielding region is used as the photomask.

When such a photomask is used in an exposure apparatus to transfer a pattern to a transfer object, when the reflectance of the photomask with respect to exposure light is high, the accuracy of transferring the pattern to the transfer object is lowered due to the influence of stray light generated by reflection of the exposure light on the photomask. In order to suppress such a problem, a technique of reducing the reflectance of the photomask to the exposure light is employed. As such a technique, for example, patent document 1 and the like describe a configuration of a photomask in which an antireflection film is provided on the front surface side of a light-shielding pattern.

On the other hand, the manufacturing technology of flat panel displays has been advanced year by year with the high resolution. Accordingly, panel manufacturers are developing a technique for forming finer patterns with high accuracy, but in recent years, in the field of exposure techniques for transferring patterns to a transfer object, there is a tendency to use a highly sensitive resist for forming finer patterns with high accuracy. Fig. 11 is a graph comparing a transfer line width shift with a variation in exposure amount using an existing low-sensitivity resist and a high-sensitivity resist used in recent years. As shown in fig. 11, the high-sensitivity resist requires less exposure amount for curing than the low-sensitivity resist, and the variation of the transfer line width shift is large in a stage where the exposure amount is small.

Therefore, with the tendency to use a high-sensitivity resist, the following problems arise: the weak stray light, which has been negligible in the past, affects the resist layer during exposure, thereby causing unevenness or dimensional variation in the pattern transferred to the transferred object.

In recent years, when forming a pattern having a large area with high accuracy, it has been required to use exposure light including light having a plurality of wavelengths such as g-line, h-line, i-line, etc., and particularly to use exposure light including j-line having a larger energy among these lights, because the energy of the exposure light irradiated to the resist layer is insufficient. On the other hand, in the case of using such exposure light, since the change of the resist layer upon exposure becomes large, the influence of the weak stray light on the resist layer becomes further large, and the above-mentioned problem becomes remarkable.

In contrast, with the configuration described in patent document 1 and the like, the intensity of stray light generated by reflection of exposure light on the photomask during exposure can be sufficiently reduced, and thus occurrence of unevenness or dimensional variation in a pattern transferred to a transfer target can be suppressed.

Documents of the prior art

Patent document

Patent document 1: japanese patent No. 4451391

Disclosure of Invention

Problems to be solved by the invention

The present invention has been made in view of the above problems, and a main object of the present invention is to provide a large photomask capable of suppressing occurrence of unevenness or dimensional variation in a pattern transferred to a transfer target.

Means for solving the problems

In order to solve the above problems, the present invention provides a large photomask including a light transmissive substrate and a light shielding pattern provided on a surface of the light transmissive substrate, the light shielding pattern having a laminated structure in which a1 st low-reflection film, a light shielding film, and a2 nd low-reflection film are laminated in this order from the light transmissive substrate side, and a reflectance of light in a wavelength region facing 313nm to 436nm on the light transmissive substrate side of the light shielding pattern is 8% or less.

According to the present invention, the occurrence of unevenness or dimensional variation in a pattern transferred to a transfer target can be suppressed.

In the above invention, it is preferable that a reflectance of light in a wavelength region of 313nm to 436nm with respect to the light-shielding pattern on the side opposite to the light-transmissive substrate is 10% or less.

In the above invention, it is preferable that the light-shielding film contains chromium, and the 1 st low reflection film and the 2 nd low reflection film contain chromium oxide.

In the above invention, it is preferable that the light-shielding pattern has an Optical Density (OD) of 4.5 or more with respect to light in a wavelength region of 313nm to 436 nm.

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

In the above invention, it is preferable that a side surface of the 1 st low reflection film or a side surface of the 2 nd low reflection film protrudes in a direction parallel to the surface of the light transmissive substrate with respect to a side surface of the light blocking film.

In particular, it is preferable that both the side surface of the 1 st low-reflection film and the side surface of the 2 nd low-reflection film protrude in a direction parallel to the surface of the light-transmissive substrate with respect to the side surface of the light-shielding film, and the side surface of the 1 st low-reflection film protrudes in a direction parallel to the surface of the light-transmissive substrate more than the side surface of the 2 nd low-reflection film.

Preferably, at least a side surface of the 1 st low reflection film protrudes in a direction parallel to the surface of the light-transmissive substrate with respect to a side surface of the light-shielding film, and an angle of the side surface of the 1 st low reflection film with respect to the surface of the light-transmissive substrate is 56 ° or less. This is because foreign matter can be easily removed by cleaning, and the amount of foreign matter present can be reduced.

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 the light shielding layer has a divided pattern for divided exposure, and the divided pattern is the light shielding pattern.

ADVANTAGEOUS EFFECTS OF INVENTION

In the present invention, the effect of suppressing occurrence of unevenness or dimensional variation in a pattern transferred to a transfer target is exhibited.

Drawings

Fig. 1 is a schematic cross-sectional view showing an example of a large photomask according to the present invention.

Fig. 2 is a schematic cross-sectional view showing a step of transferring a pattern to a resist layer of a transfer target by exposure using the large-sized photomask shown in fig. 1.

Fig. 3 is an enlarged view of the region within the dashed box shown in fig. 1, shown upside down in the drawing.

Fig. 4 is a schematic cross-sectional view showing a region corresponding to fig. 3 in a large photomask according to the related art.

Fig. 5 is a schematic cross-sectional view showing a region corresponding to fig. 3 in another example of the large photomask according to the present invention.

Fig. 6 is a schematic cross-sectional view showing a region corresponding to fig. 3 in another example of the large photomask of the present invention.

Fig. 7 is a schematic cross-sectional view showing a region corresponding to fig. 3 in another example of the large photomask of the present invention.

Fig. 8 is a schematic plan view showing another example of the large photomask of the present invention.

Fig. 9 is a schematic plan view showing a pattern transfer body produced from a transfer target body using the large-sized photomask shown in fig. 8.

Fig. 10 is a schematic process cross-sectional view showing a part of the manufacturing process of the pattern transfer member shown in fig. 9.

Fig. 11 is a graph comparing a transfer line width shift with a variation in exposure amount using an existing low-sensitivity resist and a high-sensitivity resist used in recent years.

Fig. 12 is a schematic cross-sectional view showing a region corresponding to fig. 3 in another example of the large photomask of the present invention.

Detailed Description

Hereinafter, the large photomask according to the present invention will be described in detail.

The large photomask of the present invention is a large photomask including a light-transmitting substrate and a light-shielding pattern provided on a surface of the light-transmitting substrate, the light-shielding pattern having a laminated structure in which a1 st low-reflection film, a light-shielding film, and a2 nd low-reflection film are laminated in this order from the light-transmitting substrate side, and a reflectance of light in a wavelength region of 313nm to 436nm on the light-transmitting substrate side of the light-shielding pattern is 8% or less.

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

As shown in fig. 1, the large photomask 100 includes a light-transmissive substrate 110 and a light-shielding pattern 120 provided on a surface 110a of the light-transmissive substrate 110. The light-shielding pattern 120 has a laminated structure in which a1 st low-reflection film 122, a light-shielding film 124, and a2 nd low-reflection film 126 are laminated in this order from the side of the transparent substrate 110. The light-shielding pattern 120 has a reflectance of 8% or less on the surface 120a on the translucent substrate 110 side with respect to any light having a wavelength range of 313nm to 436 nm.

Therefore, as shown in fig. 2, when a large photomask 100 is used to transfer a pattern to a transfer target 200 having a resist layer 220 formed on a base 210 by exposing the transfer target with exposure light including arbitrary light in the wavelength range from a light source (ultraviolet lamp), the intensity of stray light La originally irradiated on the resist layer 220 in a shield region where the exposure light is shielded by an exposure shield plate 300 can be reduced to, for example, less than 0.3% of the exposure illuminance by reducing the intensity of stray light generated by multiple reflections or the like in which the exposure light is alternately reflected between a surface 120a of the light-shielding pattern 120 on the light-transmissive substrate 110 side and a front surface 300a of the exposure shield plate 300 or an interface 112 between the light-transmissive substrate 110 and air (not shown). This can suppress occurrence of unevenness or dimensional variation in the pattern of the resist layer 220 transferred to the mask region.

Therefore, according to the present invention, when exposure is performed using exposure light including arbitrary light in the wavelength region, occurrence of unevenness or dimensional variation in a pattern transferred to a transfer target can be suppressed by reducing the intensity of stray light generated by reflection of the exposure light on the surface of the light-transmissive substrate side of the light-shielding pattern.

In recent years, when a large-area pattern is formed with high accuracy in the production of a flat panel display, there is a case where the energy of exposure light irradiated to a resist layer is insufficient for exposure light including g-line (wavelength 436nm), h-line (wavelength 405nm), or i-line (wavelength 365 nm). Therefore, it is required to use exposure light including light of a plurality of wavelengths such as g-line, h-line, i-line, and the like, and particularly, it is required to use exposure light including j-line (wavelength 313nm) having a large amount of energy among these light.

On the other hand, the change of the resist layer upon exposure to light including light of a plurality of wavelengths is larger than that of exposure light of a single wavelength, and particularly, the change of the resist layer upon exposure to light including j-line is larger. Therefore, when exposure light including light of a plurality of wavelengths, particularly exposure light including j-line is used, the influence of weak stray light on the resist becomes further large, and thus the problem of occurrence of unevenness in a pattern transferred to a transfer target becomes remarkable. In contrast, in the large photomask 100 shown in fig. 1, since the reflectance is 8% or less for any light in the wavelength region, the reflectance of the surface 120a of the light-shielding pattern 120 on the transparent substrate 110 side can be reduced to 8% or less for any of the g-line, the h-line, the i-line, and the j-line.

Therefore, according to the present invention, when exposure light including light of a plurality of wavelengths such as g-line, h-line, i-line, and the like, particularly exposure light including j-line, is used for exposure, occurrence of unevenness or the like in a pattern transferred to a transferred object can be significantly suppressed.

1. Shading pattern

The light-shielding pattern is provided on the surface of the light-transmissive substrate, and has a laminated structure in which the 1 st low-reflection film, the light-shielding film, and the 2 nd low-reflection film are laminated in this order from the light-transmissive substrate side, and the light-shielding pattern has a reflectance of light in a wavelength region of 313nm to 436nm on the light-transmissive substrate side of 8% or less.

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

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

The light-transmitting substrate-side surface of the light-shielding pattern is not particularly limited as long as the light-transmitting substrate-side surface has a reflectance of 8% or less with respect to light in the wavelength region, but among these, a light-transmitting substrate-side surface having a reflectance of 5% or less with respect to light in the wavelength region of 365nm to 436nm is preferable. When exposure is performed using exposure light including arbitrary light in a wavelength region of 365nm to 436nm, the intensity of the stray light La shown in fig. 2 can be reduced to, for example, 0.2% of the exposure illuminance. This is because the intensity of the stray light can be reduced from the level of the boundary at which the resist layer of the transferred object is exposed to light to a level at which the influence is not generated at all. In particular, the reflectance for light in the wavelength region of 313nm to 365nm is preferably 5% or less. This is because the same effect can be obtained when exposure is performed using exposure light including light in a wider range of wavelength regions. More specifically, this is because the same effect can be obtained not only with the existing exposure apparatus and resist using the exposure light in the wavelength region of 365nm to 436nm but also with other exposure apparatuses and resists using the exposure light in the wavelength region of 313nm to 365 nm.

In the present invention, as a method of measuring the reflectance of the surface of the light-transmitting substrate side of the light-shielding pattern, a device (tsukamur electronic MCPD) using a photodiode array as a detector can be used.

Preferably, the light-shielding pattern has a reflectance of light in a wavelength region of 313nm to 436nm with respect to the side opposite to the light-transmissive substrate of 10% or less. That is, it is preferable that the light-shielding pattern has a reflectance of 10% or less on a surface opposite to the transparent substrate for any light in the wavelength region.

The method of measuring the reflectance of the surface of the light-shielding pattern on the side opposite to the light-transmissive substrate is the same as the reflectance of the surface of the light-shielding pattern on the side of the light-transmissive substrate.

In the large photomask 100 shown in fig. 1, the reflectance of the surface 120b of the light-shielding pattern 120 on the side opposite to the transparent substrate 110 is 10% or less for any light having a wavelength range of 313nm to 436 nm. Therefore, as shown in fig. 2, when a pattern is transferred to a transferred object 200 having a resist layer 220 formed on a base 210 by exposure using exposure light including arbitrary light in the wavelength region using a large photomask 100, the intensity of stray light Lb, which is generated by multiple reflections or the like in which the exposure light is alternately reflected between air (not shown) and the interface 212 of the resist layer 220 or the interface 214 of the resist layer 220 and the base 210 on the surface 120b of the light-shielding pattern 120 opposite to the transparent substrate 110, and the like, can be reduced to, for example, 2.0% of the exposure illuminance by reducing the intensity of stray light. Thereby, occurrence of dimensional deviation or the like in the pattern of the resist layer 220 transferred to the edge portion can be suppressed.

Therefore, the reflectance with respect to light in the above wavelength region is preferably 10% or less. This is because, when exposure is performed using exposure light including arbitrary light in the wavelength region, the intensity of stray light generated by reflection of the exposure light on the surface of the light-shielding pattern opposite to the light-transmissive substrate is reduced, and thus occurrence of dimensional variations and the like in the pattern transferred to the object to be transferred can be effectively suppressed. This is because, when exposure light including light of a plurality of wavelengths such as g-line, h-line, i-line, and the like, particularly exposure light including j-line, is used for exposure, occurrence of dimensional deviation and the like in a pattern transferred to a transferred object can be more remarkably suppressed.

The light-shielding pattern preferably has a reflectance of 10% or less with respect to light in the wavelength region, but preferably has a reflectance of 5% or less with respect to light in the wavelength region of 365nm to 436 nm. When exposure is performed using exposure light including arbitrary light in a wavelength region of 365nm to 436nm, the intensity of the stray light Lb shown in fig. 2 can be reduced to, for example, 1.0% of the exposure illuminance. This is because the intensity of the stray light can be reduced to a level at which the size deviation or the like does not occur at all at the level of the boundary line at which the resist layer is exposed to light at the level of the size deviation or the like occurring in the pattern of the resist layer of the object transferred to the edge portion of the light-shielding pattern. In particular, a surface having a reflectance of 5% or less with respect to light in a wavelength region of 313nm to 365nm is preferable. This is because the same effect can be obtained when exposure is performed using exposure light including light in a wider range of wavelength regions. More specifically, this is because the same effect can be obtained not only with the existing exposure apparatus and resist using the exposure light in the wavelength region of 365nm to 436nm but also with other exposure apparatuses and resists using the exposure light in the wavelength region of 313nm to 365 nm.

(2) No. 1 Low reflection film

The 1 st 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 achieves a function of reducing the reflectance of light in a wavelength region of 313nm to 436nm to 8% or less on the light-transmitting substrate side of the light-shielding pattern.

When the light shielding pattern has the 1 st low-reflection film, when the light in the wavelength region is irradiated to the surface of the light shielding pattern on the light transmitting substrate side, light reflected by the surface of the 1 st low-reflection film on the light transmitting substrate side, light reflected by an interface in the 1 st low-reflection film, and light reflected by a boundary between the 1 st low-reflection film and the light shielding film are attenuated by interference with each other. This can reduce the reflectance of light in the wavelength region on the side of the light-transmitting substrate of the light-shielding pattern to 8% or less.

As described above, when exposure light including light of a plurality of wavelengths such as g-line, h-line, i-line, and the like, particularly exposure light including j-line, is used, the influence of weak stray light on the resist becomes further large, and therefore, the problem of occurrence of unevenness or the like in a pattern transferred to a transfer target becomes remarkable. On the other hand, it is difficult to form a film that realizes a function of reducing the reflectance of light in the wavelength region to 8% or less on the side of the light-transmissive substrate of the light-shielding pattern to solve such a problem. In the present invention, although this is the case, a film that realizes a function of reducing the reflectance of light in the wavelength region on the side of the light-transmitting substrate to 8% or less can be formed.

a. No. 1 Low reflection film

The thickness of the 1 st low-reflection film is not particularly limited as long as the function of reducing the reflectance of light in the wavelength region on the side of the light-transmitting substrate of the light-shielding pattern to 8% or less is achieved, but is preferably within a range of 10nm to 50 nm. This is because if the thickness is too small, the function of reducing the reflectance is reduced, and if the thickness is too large, it is difficult to process the light-shielding pattern with high precision.

The material of the 1 st low reflection film is not particularly limited as long as it can reduce the reflectance of light in the wavelength region on the light transmitting substrate side of the light shielding pattern to 8% or less, and examples thereof include: chromium oxide (CrOx), chromium oxynitride (CrON), chromium nitride (CrN), titanium oxide (TiO), titanium oxynitride (TiON), tantalum oxide (TaO), tantalum silicon oxide (TaSiO), nickel aluminum oxide (NiAlO), molybdenum silicon oxide (MoSiO), molybdenum silicon oxynitride (MoSiON), and the like. Among them, chromium oxide (CrOx) and chromium oxynitride (CrON) are preferable, and chromium oxide (CrOx) is particularly preferable.

b. Forming method

Examples of the method for forming the 1 st low reflection film include a sputtering method, a vacuum deposition method, and an ion plating method. More specifically, for example, there are listed: the Cr target material is installed in a vacuum chamber, and O is introduced₂、N₂、CO₂A gas, a method of forming a film by reactive sputtering in a vacuum atmosphere, and the like.

In this method, O is increased as compared with the case of forming a low reflection film in a light shielding pattern of a general binary mask₂The ratio of the gas reduces the reflectance of light in a wavelength region of 313nm to 436nm on the side of the light-transmitting substrate of the light-shielding pattern to 8% or less.

(3) No. 2 low reflection film

The 2 nd low reflection film is provided on the side opposite to the transparent substrate in the laminated structure of the light shielding pattern, and is a film that achieves a function of reducing the reflectance of light in a wavelength region of 313nm to 436nm with respect to the side opposite to the transparent substrate of the light shielding pattern.

When the light shielding pattern has the 2 nd low reflection film, when light in the wavelength region enters the surface of the light shielding pattern opposite to the transparent substrate, light reflected on the surface of the 2 nd low reflection film opposite to the transparent substrate, light reflected on the interface inside the 2 nd low reflection film, and light reflected on the boundary between the 2 nd low reflection film and the light shielding film are attenuated by interference with each other. This reduces the reflectance of the light in the wavelength region of the light-shielding pattern opposite to the light-transmissive substrate.

a. No. 2 low reflection film

The 2 nd low reflection film is not particularly limited as long as it has a function of reducing the reflectance of light in the wavelength region of 313nm to 436nm facing the light-shielding pattern on the side opposite to the transparent substrate, but is preferably a film having a function of reducing the reflectance of light in the wavelength region of 313nm to 436nm facing the opposite side to 10% or less.

As described above, in the case of using exposure light including light of a plurality of wavelengths such as g-line, h-line, i-line, and the like, particularly exposure light including j-line, the influence of weak stray light on the resist becomes further large, and therefore the problem of occurrence of dimensional deviation and the like in the pattern transferred to the object becomes remarkable. On the other hand, it is difficult to effectively solve such a problem by forming an antireflection film that realizes a function of reducing the reflectance of light in the wavelength region of the light shielding pattern on the side opposite to the light transmissive substrate to 10% or less. In the present invention, although this is the case, a film that achieves the function of reducing the reflectance of light in the wavelength region on the opposite side to 10% or less can be formed.

The thickness of the 2 nd low reflection film is not particularly limited as long as the function of reducing the reflectance of light in the wavelength region of the light shielding pattern on the side opposite to the transparent substrate is achieved, but is preferably in the range of 10nm to 50 nm. This is because if the thickness is too small, the function of reducing the reflectance is reduced, and if the thickness is too large, it is difficult to process the light-shielding pattern with high precision.

The material of the 2 nd low reflection film is the same as that of the 1 st low reflection film, and therefore, the description thereof is omitted here.

b. Forming method

A method for forming the 2 nd low reflection film to reduce the reflectance of light in a wavelength region of 313nm to 436nm facing the side opposite to the light-transmitting substrate of the light-shielding pattern to 10% or less is the same as the method for forming the 1 st low reflection film, and therefore, a description thereof is omitted here.

(4) Light-shielding film

The light-shielding film is a film having light-shielding properties provided between the 1 st low-reflection film and the 2 nd low-reflection film in the laminated structure of the light-shielding pattern.

a. Light-shielding film

The film thickness of the light-shielding film is not particularly limited, but is preferably in the range of 80nm to 180 nm. This is because it is difficult to obtain a desired light-shielding property when the thickness is too small, and it is difficult to process the light-shielding pattern with high precision when the thickness is too large.

The material of 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 silicon oxide (MoSiO), molybdenum silicon oxynitride (MoSiON), tantalum oxide (TaO), tantalum silicon oxide (TaSiO), and the like. Among them, chromium (Cr) is preferable.

b. Method for forming light-shielding film

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

In addition, as a method for forming the light-shielding film in which the light-shielding pattern has an Optical Density (OD) of 4.5 or more with respect to light in the wavelength region, for example, there can be mentioned: a method of extending the film formation time of the light-shielding film more than usual, a method of increasing the number of film formation scans, and the like.

(5) Shading pattern

a. Optical Density (OD)

The light-shielding pattern preferably has an Optical Density (OD) of 4.5 or more with respect to light in a wavelength region of 313nm to 436 nm. That is, the Optical Density (OD) is preferably 4.5 or more for any light in the above wavelength region.

In the present invention, an ultraviolet/visible spectrophotometer (Hitachi U-4000) can be used as a method for measuring the Optical Density (OD) of light in the above wavelength region.

In the large photomask 100 shown in fig. 1, the light-shielding pattern 120 has an Optical Density (OD) of 4.5 or more with respect to light in a wavelength region of 313nm to 436 nm. That is, the Optical Density (OD) of the light-shielding pattern 120 is 4.5 or more for any light in this wavelength region. Therefore, as shown in fig. 2, when a large photomask 100 is used and a pattern is transferred to the transferred object 200 having the resist layer 220 formed on the base 210 by exposing with exposure light including arbitrary light in the wavelength region, the intensity of the transmitted light Lc of the exposure light transmitted through the light-shielding pattern 120 can be reduced to, for example, 0.001% or less of the exposure illuminance. This can suppress the occurrence of unevenness in the pattern transferred to the resist layer 220.

Therefore, the Optical Density (OD) is preferably 4.5 or more. This is because, when exposure is performed using exposure light including arbitrary light in the wavelength region, unevenness in a pattern transferred to a transfer target can be effectively suppressed by reducing the intensity of transmitted light of the exposure light transmitted through the light-shielding pattern. This is because exposure light including light of a plurality of wavelengths such as g-line, h-line, i-line, and the like, particularly exposure light including j-line, can effectively suppress occurrence of unevenness in a pattern transferred to a transfer target.

In general, it is not desirable to increase the Optical Density (OD) of the light-shielding pattern in the photomask because the light-shielding pattern becomes thick and it is difficult to perform high-precision processing. This tendency is particularly remarkable in photomasks used in the manufacture of semiconductor integrated circuits.

b. Size of

(a) Width of

The width of the light-shielding pattern is, for example, 0.1 μm or more and less than 10.0. mu.m. The width of the light-shielding pattern is preferably a width in which the size is controlled to a submicron level.

The width of the light-shielding pattern is defined by the dimension in the short side direction of the planar shape. The width after the dimension control at the submicron level is a width after the dimension control at the unit of 0.1 μm, for example, a width of 0.1 μm or more and less than 1.0 μm.

(b) Film thickness

The overall film thickness of the light-shielding pattern is preferably in the range of 100nm to 250nm, although not particularly limited. This is because it is difficult to obtain a desired light-shielding property when the thickness is too small, and it is difficult to process the light-shielding pattern with high precision when the thickness is too large.

c. Cross-sectional shape

The light-shielding pattern preferably has an Optical Density (OD) of 4.5 or more with respect to light in the wavelength region and has a desired cross-sectional shape. Hereinafter, a preferred cross-sectional shape of the light-shielding pattern will be described.

Fig. 3 is an enlarged view of a region within the broken line frame shown in fig. 1, with the drawing upside down. As shown in fig. 3, in the large photomask 100 shown in fig. 1, the light-shielding pattern 120 has an Optical Density (OD) of 4.5 or more with respect to light in a wavelength region of 313nm to 436 nm. In the opening 120c of the light-shielding pattern 120, the side surface 124a of the light-shielding film 124 is inclined at an angle α of 80 degrees or more and 90 degrees or less with respect to the light-transmissive substrate 110. On the other hand, fig. 4 is a schematic cross-sectional view showing a region corresponding to fig. 3 in a large photomask according to the related art. As shown in fig. 4, in the large photomask 100 according to the related art, the inclination angle α of the side surface 124a of the light-shielding film 124 with respect to the transparent 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-transmissive substrate 110 is 80 degrees or more and 90 degrees or less, unlike the case where the inclination angle α is less than 80 degrees shown in fig. 4, the possibility that the reflected light of the exposure light (stray light) irradiated from the direction inclined from the light source side to the side surface 124a of the light-shielding film 124 is guided to the side of the opening 120c of the light-shielding pattern 120 at the time of exposure in which the pattern is transferred to the resist layer of the transferred object increases. Therefore, the reflected light can be prevented from being irradiated to the resist layer which blocks the irradiation of the exposure light by the edge portion of the light-shielding pattern 120. Thereby, occurrence of dimensional variations and the like in the pattern of the resist layer transferred into the edge portion can be suppressed.

Therefore, as the light-shielding pattern having an Optical Density (OD) of 4.5 or more with respect to light in the wavelength region, it is preferable that an inclination angle of the side surface of the light-shielding film with respect to the light-transmissive substrate is 80 degrees or more and 90 degrees or less as shown in fig. 3. This is because, since the light-shielding pattern is thick so that the Optical Density (OD) is 4.5 or more, although the amount of reflected light of exposure light applied to the side surface of the light-shielding film from the oblique direction of the light source side increases, the occurrence of dimensional variations and the like in the pattern transferred to the object to be transferred can be suppressed by the influence of the reflected light.

The inclination angle of the side surface of the light-shielding film with respect to the light-transmissive substrate is: an inclination angle of a tangent line to an edge of the light transmissive substrate side in the side surface of the light shielding film, which is denoted by α in fig. 3.

Fig. 5 to 7 are schematic cross-sectional views each showing a region corresponding to fig. 3 in another example of the large photomask according to the present invention.

In the large photomask 100 shown in fig. 5, the light-shielding pattern 120 has an Optical Density (OD) of 4.5 or more with respect to light in a wavelength region of 313nm 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-transmissive substrate 110, and the side surface 122a of the 1 st low reflection film 122 and the side surface 126a of the 2 nd low reflection film 126 protrude from the side surface 124a of the light-shielding film 124 by a length L1 in a direction parallel to the light-transmissive substrate 110.

In the large photomask 100 shown in fig. 6, the light-shielding pattern 120 has an Optical Density (OD) of 4.5 or more with respect to light in a wavelength region of 313nm 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 including a plurality of planes, and the side surface 122a of the 1 st low reflection film 122 and the side surface 126a of the 2 nd low reflection film 126 protrude in the direction parallel to the transparent substrate 110 with respect to the side surface 124a of the light-shielding film 124 by a length L2 from the side surface 124a of the light-shielding film 124 farthest from the opening 120 c. The side surface 124a of the light-shielding film 124 is recessed by a width W1 in a direction parallel to the light-transmissive substrate 110 from a position closest to the opening 120c to a position farthest from the opening 120 c.

In the large photomask 100 shown in fig. 7, the light-shielding pattern 120 has an Optical Density (OD) of 4.5 or more with respect to light in a wavelength region of 313nm 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 curved surface. The side surface 124a of the light-shielding film 124 is recessed by a width W2 in a direction parallel to the light-transmissive substrate 110 from a position closest to the opening 120c to a position farthest from the opening 120 c.

In the large-sized photomask 100 shown in fig. 5 and 6, the side surface 122a of the 1 st low reflection film 122 and the side surface 126a of the 2 nd low reflection film 126 protrude in a direction parallel to the surface 110a of the transparent substrate 110 with respect to the side surface 124a of the light-shielding film 124. Therefore, when performing exposure for transferring a pattern to a resist layer of a transfer object, exposure light (stray light) irradiated from a direction inclined from the light source side to the side surface 124a of the light-shielding film 124 is reduced in intensity by the 1 st low reflection film 122 and then irradiated to the side surface 124a of the light-shielding film 124. The reflected light of the exposure light irradiated to the side surface 124a of the light-shielding film 124 is irradiated to the resist layer after the intensity thereof is reduced by the 2 nd low-reflection film 126. Therefore, the intensity of the exposure light applied to the side surface 124a of the light shielding film 124 from the oblique direction of the light source side when the resist layer is irradiated with the exposure light can be suppressed by the 1 st low reflection film 122 and the 2 nd low reflection film 126.

Therefore, as the light-shielding pattern having an Optical Density (OD) of 4.5 or more with respect to light in the wavelength region, a light-shielding pattern in which a side surface of the 1 st low-reflection film or a side surface of the 2 nd low-reflection film protrudes in a direction parallel to the surface of the transparent substrate with respect to a side surface of the light-shielding film is preferable as shown in fig. 5 and 6. This is because, since the light-shielding pattern is thick so that the Optical Density (OD) is 4.5 or more, although the amount of reflected light of exposure light applied to the side surface of the light-shielding film from the oblique direction of the light source side increases, the occurrence of unevenness in the pattern transferred to the object to be transferred can be suppressed by the influence of the reflected light.

Further, the side surface of the 1 st low reflection film or the side surface of the 2 nd low reflection film is not particularly limited as long as it protrudes in a direction parallel to the surface of the light-transmissive substrate with respect to the side surface of the light-shielding film, but both of the side surfaces are preferably protruded.

In addition, in the case where the side surface of the 1 st low reflection film or the side surface of the 2 nd 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, the protruding length indicated by L1 and L2 in fig. 5 and 6 is preferably 1/2 or more of the film thickness of the light-shielding film. This is because the occurrence of unevenness in the pattern transferred to the object to be transferred can be effectively suppressed by the influence of the reflected light.

The above-mentioned projection length means: a side surface of the 1 st low reflection film or a side surface of the 2 nd low reflection film protrudes in a direction parallel to the surface of the light transmissive substrate from a position farthest from the opening of the light shielding pattern in the concave side surface of the light shielding film.

In the present invention, it is preferable that a side surface of the 1 st low reflection film or a side surface of the 2 nd low reflection film protrudes in a direction parallel to the surface of the light transmissive substrate with respect to a side surface of the light blocking film for the following reason.

That is, in general, a metal film of chromium or the like has higher polarity than a metal oxide film of chromium oxide or the like, and thus foreign substances tend to be easily attached. Therefore, in the case where 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 transparent substrate with respect to the side surface of the 1 st low-reflection film or the side surface of the 2 nd low-reflection film, the possibility of adhesion of foreign matter to the light-shielding film increases, and it may be difficult to remove the foreign matter by cleaning after that.

In view of such adhesion of foreign matter, it is also preferable that the side surface of the 1 st low reflection film or the side surface of the 2 nd low reflection film protrudes in a direction parallel to the surface of the light-shielding film with respect to the side surface of the light-transmissive substrate, and it is particularly preferable that both of these side surfaces protrude.

In the present invention, the order of the side surfaces protruding in the direction parallel to the surface of the light transmissive substrate is preferably the order of the side surface of the 1 st low reflection film protruding most, the side surface of the 2 nd low reflection film, and the side surface of the light blocking film. This is because, when the foreign matter is present in the vicinity of the side surfaces of these laminated bodies, the side surfaces of the 1 st low reflection film protrude most, and therefore the area of contact between the foreign matter and the metal oxide film is large, and therefore the foreign matter is likely to come into contact with each other, and as a result, the foreign matter is also likely to peel off.

On the other hand, in the present invention, at least the side surface of the 1 st 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, and it is more preferable that the angle of the side surface of the 1 st low reflection film with respect to the surface of the light-transmissive substrate is 56 ° or less.

Fig. 12 shows a part 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 1 st low-reflection film 122 and the side surface 126a of the 2 nd low-reflection film 126 protrude in a direction parallel to the surface 110a of the transparent substrate 110 with respect to the side surface 124a of the light-shielding film 124. An angle α formed between the side surface 122a of the 1 st low reflection film 122 and the front surface 110a of the transparent substrate 110 is 56 ° or less.

As described above, since the angle of the side surface of the 1 st low reflection film with respect to the surface of the transparent substrate is 56 ° or less, even when foreign matter adheres thereto, the contact area of the cleaning fluid during cleaning can be increased, and therefore cleaning can be efficiently performed, and defects caused by the presence of foreign matter after the cleaning process can be prevented.

Wherein an angle of the side surface of the 1 st low reflection film with respect to the surface of the transparent substrate is: an angle obtained by connecting a position a where the side surface 122a of the 1 st low reflection film 122 is in contact with the front surface 110a of the transparent substrate 110 and a position B where the film thickness of the 1 st low reflection film 122 starts to decrease with a straight line and measuring an angle between the straight line and the front surface 110 a.

The protrusion of the side surface 122a of the 1 st low reflection film 122 from the side surface 124a of the light shielding film 124 means: the position B at which the film thickness of the 1 st low reflection film 122 starts to decrease protrudes in a direction parallel to the surface 110a of the transparent substrate 110 with respect to the side surface 124a of the light-shielding film 124.

In the present invention, an angle of the side surface of the 1 st low-reflection film with respect to the surface of the transparent substrate is preferably 56 ° or less, and particularly preferably 40 ° or less. The reason for this is that the cleaning can be performed more efficiently. Although the angle is preferably small, it is preferably 20 ° or more from the viewpoint of manufacturing difficulty in actual manufacturing.

In the present invention, it is preferable that the side surface of the 2 nd low reflection film also protrudes in a direction parallel to the surface of the transparent substrate than the side surface of the light-shielding film. This is because the adhesion of foreign matter to the side surface of the light-shielding film, which may be difficult to remove by cleaning due to the effect of the adhesion to the foreign matter, can be reduced.

In the large photomask 100 shown in fig. 6 and 7, the side surface 124a of the light-shielding film 124 is concave. Therefore, in the exposure for transferring a pattern to a resist layer of a transferred object, there is an increased possibility that reflected light of exposure light (stray light) applied to the side surface 124a of the light-shielding film 124 from a direction inclined from the light source side is guided to the light source side or the opening 120c side of the light-shielding pattern 120. Therefore, the reflected light can be prevented from being irradiated to the resist layer which blocks the irradiation of the exposure light by the edge portion of the light-shielding pattern 120. Thereby, occurrence of dimensional variations and the like in the pattern of the resist layer transferred into the edge portion can be suppressed.

Therefore, as the light-shielding pattern having an Optical Density (OD) of 4.5 or more with respect to light in the wavelength region, a light-shielding pattern having a concave side surface is preferable as shown in fig. 6 and 7. This is because, since the light-shielding pattern is thick so that the Optical Density (OD) is 4.5 or more, although the amount of reflected light of exposure light applied to the side surface of the light-shielding film from the oblique direction of the light source side increases, the occurrence of dimensional variations and the like in the pattern transferred to the object to be transferred can be suppressed by the influence of the reflected light.

The light-shielding pattern having a concave side surface is preferably a light-shielding pattern having a concave width of 1/2 or more of the film thickness of the light-shielding film, as indicated by W1 and W2 in fig. 6 and 7. This is because the influence of the reflected light effectively suppresses the occurrence of dimensional variations and the like in the pattern transferred to the object to be transferred.

The recessed width is: and a width of the side surface of the light-shielding film in a direction parallel to the surface of the light-transmissive substrate from a position closest to the opening of the light-shielding pattern to a position farthest 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 and the 1 st and 2 nd low reflection films may be a clear boundary or an undefined boundary. From the viewpoint of easy individual control of the characteristics of each film, a light-shielding pattern having the above-described clear boundary is preferable. In addition, from the viewpoint of smooth processing surface or easy production, a light-shielding pattern having the above-described undefined boundary is preferable.

The light-shielding pattern having the above-mentioned clear boundary can be produced by: the film formation of the 1 st low reflection film, the light-shielding film, and the 2 nd low reflection film is performed individually using a sputtering apparatus in which a gas is replaced. Further, the light-shielding pattern having the above-described unclear boundaries can be produced by: the film formation of the 1 st low reflection film, the light-shielding film, and the 2 nd low reflection film is continuously performed without changing the sputtering apparatus gas.

e. Forming method

Examples of the method for forming the light-shielding pattern include the following methods: after a light-shielding layer having a laminated structure in which a1 st low-reflection film, a light-shielding film, and a2 nd low-reflection film are laminated in this order is formed on the surface of synthetic quartz glass, a resist pattern having 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.

2. Light-transmitting substrate

The size of the light-transmitting substrate is not particularly limited as long as it can be formed into a photomask having a size of 350mm or more on at least one side, and is appropriately selected depending on the use of the large photomask of the present invention, and is preferably 330mm × 450mm or more, and more preferably in the range of 330mm × 450mm to 1700mm × 1800 mm.

The thickness of the transparent substrate may be appropriately selected according to the material, application, and the like of the large photomask. The thickness of the transparent substrate is, for example, about 8mm to 17 mm.

The light-transmitting substrate is light-transmitting, and a light-transmitting substrate used for a general large photomask can be used. Examples of the light-transmitting substrate include low-expansion glass (alumino-borosilicate glass, borosilicate glass) after optical polishing, and synthetic quartz glass. In the present invention, among them, synthetic quartz glass is suitably used. This is because the thermal expansion coefficient is small, and a large photomask can be easily manufactured. In the present invention, the light-transmitting substrate may be made of a resin.

The light transmittance of the light-transmissive substrate is not particularly limited as long as it is about the same as that of a light-transmissive substrate used for a general large photomask, but the light transmittance of the light-transmissive substrate in a wavelength region of 313nm to 436nm is preferably 80% or more, more preferably 85% or more, and particularly preferably 90% or more. This is because, in a translucent substrate having a high purity, the light passing through the translucent substrate is less scattered in the material, and the refractive index is also low, so that the occurrence of stray light can be suppressed.

3. Others

The large photomask of the present invention is not particularly limited as long as it is a large photomask that includes the light-transmissive substrate and the light-shielding pattern, and in which the light-shielding pattern has a reflectance of light in the wavelength region on the light-transmissive substrate side of the light-shielding pattern of 8% or less, but is preferably a large photomask that includes a division pattern for division exposure, and in which the division pattern is the light-shielding pattern.

The divisional exposure refers to the following method: a transfer target area is divided into a plurality of exposure areas in a transfer target body, each of the plurality of exposure areas is individually exposed using a large photomask, and a continuous pattern larger than the divided pattern of the photomask is formed on the transfer target body by transferring the divided pattern of the photomask to each of the plurality of exposure areas.

Such a preferred large photomask will be described with reference to the drawings. Fig. 8 is a schematic plan view showing another example of the large photomask of the present invention. Fig. 9 is a schematic plan view showing a pattern transfer body manufactured from a transfer object by using the large-sized photomask shown in fig. 8. Fig. 10(a) to 10(b) are schematic process cross-sectional views showing a part of the process for producing the pattern transfer member shown in fig. 9.

As shown in fig. 8, the large photomask 100 includes: a light-transmissive substrate 110; and a1 st divided pattern 150a, a2 nd divided pattern 150b, and a3 rd divided pattern 150c which are different from each other and provided on the front surface 110a of the transparent substrate 110. The 1 st, 2 nd and 3 rd divided

patterns

150a, 150b and 150c are each a light-shielding pattern 120 having a laminated structure in which a1 st low-reflection film 122, a light-shielding film 124 and a2 nd low-reflection film 126 are laminated in this order from the side of the transparent substrate 110, similarly to the light-shielding pattern 120 shown in fig. 1. Therefore, the surfaces of the 1 st, 2 nd, and 3 rd divided

patterns

150a, 150b, and 150c on the side of the transparent substrate 110 have a reflectance of light in a wavelength region of 313nm to 436nm of 8% or less, as in the light-shielding pattern 120 shown in fig. 1.

The pattern transfer body 200' shown in fig. 9 is manufactured by exposure as follows: using the large photomask 100 shown in fig. 8, exposure light including arbitrary light in the wavelength range described above is emitted from a light source (UV lamp) to each of the patterns of the 1 st divided pattern 150a, the 2 nd divided pattern 150b, and the 3 rd divided pattern 150c in the resist layer 220 of the object 200 to be transferred.

In the case of manufacturing the pattern transfer body 200', first, in the 1 st exposure, the resist layer 220 is irradiated with the exposure light through only the 1 st divided pattern 150a out of the 1 st to 3 rd divided patterns by shielding the 2 nd divided pattern 150b and the 3 rd divided pattern 150c with the exposure shielding plate 300 (as shown in fig. 10). Next, in the 2 nd to 6 th exposures, the 3 rd divided pattern 150c and the 1 st divided pattern 150a are shielded by the exposure shield plate 300, and the resist layer 220 is irradiated with the exposure light through only the 2 nd divided pattern 150b out of the 1 st to 3 rd divided patterns. Next, in the 7 th exposure, the 1 st divided pattern 150a and the 2 nd divided pattern 150b are shielded by the exposure shield plate 300, and the resist layer 220 is irradiated with the exposure light through only the 3 rd divided pattern 150c out of the 1 st to 3 rd divided patterns. Thus, the 1 st resist pattern 220a to which the 1 st divided pattern 150a is transferred, the 5 nd 2 nd resist pattern 220b to which the 2 nd divided pattern 150b is transferred, and the 1 rd 3 rd resist pattern 220c to which the 3 rd divided pattern 150c is transferred are formed to be continuous in a single direction. As a result, a continuous single resist pattern is formed.

In the 2 nd exposure, as shown in fig. 10(a), similarly to the step shown in fig. 2, by reducing the intensity of stray light generated by reflection of the exposure light on the surface 120a of the 2 nd divided pattern 150b (light-shielding pattern 120) on the translucent substrate 110 side, the intensity of stray light La originally irradiated on the resist layer 220 in the shielding region (3 rd exposure region) where the exposure light is shielded by the exposure shielding plate 300 can be reduced. Further, by reducing the intensity of stray light generated by reflection of the exposure light on the surface 120b of the 2 nd divided pattern 150b opposite to the transparent substrate 110, the intensity of stray light Lb originally irradiated on the resist layer 220 in the 2 nd exposure region where the edge portion of the 2 nd divided pattern 150b blocks irradiation of the exposure light can be reduced.

In the 3 rd exposure, as shown in fig. 10(b), by reducing the intensity of stray light, similarly to the 2 nd exposure, the intensity of stray light Lb applied to the resist layer 220 in the region irradiated with the stray light La in the 2 nd exposure can be reduced, and the intensity of stray light La applied to the resist layer 220 in the region irradiated with the stray light Lb in the 2 nd exposure can be reduced.

Therefore, according to the preferred large photomask, when the divided exposure is performed by using the large photomask to expose each of the plurality of exposure regions of the object to be transferred individually, even if the other exposure regions are irradiated with stray light generated by reflection of the exposure light on the respective surfaces of the light-shielding pattern, the intensity of the stray light can be reduced in the case of multiple exposure in which the resist layer generates the stray light. Therefore, occurrence of unevenness or dimensional variation in the pattern transferred to the object to be transferred can be significantly suppressed.

In the divided exposure, multiple exposures may occur in a portion where adjacent exposure regions are connected due to the influence of the alignment accuracy of the exposure apparatus. Therefore, when multiple exposure due to the stray light is further generated, the problem of occurrence of unevenness or dimensional variation in the pattern transferred to the object tends to be increased. Therefore, the above-described effects can be more remarkably obtained.

4. Method for manufacturing large photomask

The method for manufacturing a large photomask according to the present invention is not particularly limited as long as the large photomask having the above-described configuration can be manufactured, and the method can be the same as the method for manufacturing a general large photomask.

For example, a synthetic quartz glass is prepared as a light-transmitting substrate, and a mask blank having a light-shielding layer having a laminated structure in which a1 st low-reflection film, a light-shielding film, and a2 nd low-reflection film are laminated in this order is produced on the surface of the synthetic quartz glass. Next, a resist pattern having 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, thereby forming a light-shielding pattern from the light-shielding layer. Thus, a large photomask is produced.

The etching solution used for the wet etching is not particularly limited as long as the light-shielding layer can be processed with high precision and the light-transmissive substrate is not damaged, and for example, a cerium ammonium nitrate solution or the like can be used.

5. Use of

The large photomask of the present invention can be suitably used for photolithography in the production of a pattern transfer material such as a functional element for a display device used in a display device.

Functional elements for display devices manufactured using the large-sized photomask of the present invention include, for example, TFT substrates, metal-clad wiring substrates used for TFT substrates and the like, color filters, substrates with light-shielding portions used for color filters, and the like.

The method for producing a pattern transfer body such as a functional element for a display device using a large photomask according to the present invention is not particularly limited, and may be the same as a general production method using a production method of a large photomask. For example, the following production methods are mentioned: the method includes an exposure step of preparing a transfer target having a resist layer, and exposing the resist layer by irradiating exposure light through a large photomask, and a development step of developing the exposed resist layer.

The resist used for the resist layer may be a positive resist or a negative resist, as in the case of a general resist. Examples of the positive resist include a phenol resin, a novolac epoxy resin, an acrylic resin, polyimide, and a cycloolefin. Specifically, there are mentioned IP3500(TOK (Tokyo Ohka Kogyo, Tokyo Kaisha), PFI27 (Sumitomo chemical Co., Ltd.), ZEP7000 (Rui Wen corporation), positive resist (JSR Corp.), and the like. Among them, a positive resist (manufactured by JSR corporation) and the like are preferable. This is because the effect of the present invention becomes remarkable because of the high sensitivity. On the other hand, examples of the negative resist include acrylic resins. Specifically, examples thereof include polyglycidyl methacrylate (PGMA), chemically amplified SAL601 (CYPRES), and negative resist (JSR). Among them, negative resists (manufactured by JSR corporation) and the like are preferable. This is because the effect of the present invention becomes remarkable because of the high sensitivity. In the case where a functional element for a display device manufactured using the large photomask of the present invention uses a developed resist layer as a constituent member, the resist layer may contain a functional material such as a colorant such as a pigment or a dye, or inorganic oxide fine particles.

The thickness of the resist layer is not particularly limited, and is, for example, in the range of 10nm to 10 μm. A known method can be used for forming the resist layer, and therefore, the description thereof is omitted.

The transferred body generally has a base for forming a resist layer. In addition, a metal layer or the like may be provided. The transfer target is appropriately selected according to the type of the functional element for display device to be manufactured.

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 a wavelength range of 313nm to 436 nm. The exposure light is preferably exposure light containing light of a plurality of wavelengths such as g-line, h-line, i-line, and particularly preferably exposure light containing j-line. This is because the energy of the exposure light irradiated to the resist layer can be increased, the exposure can be completed in a shorter exposure time, and the occurrence of unevenness in the pattern transferred to the object to be transferred can be significantly suppressed. As the light source for the exposure light, for example, an ultra-high pressure mercury lamp (ultra-high pressure UV lamp) or the like can be used.

As a method for developing the resist layer used in the above-described developing step, a general method can be used, and there is no particular limitation. As the developing method, for example, a method using a developer can be suitably employed.

The present invention is not limited to the above embodiments. The above-described embodiments are examples, and any embodiments having substantially the same configuration and exhibiting the same operational effects as the technical ideas described in the claims of the present invention are included in the technical scope of the present invention.

Examples

A. Reflectance and optical density

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

Example A1

First, a mask blank is produced, which includes: synthetic quartz glass (light-transmitting substrate) which is precisely polished to have a longitudinal X transverse X film thickness of 700mm X800 mm X8 mm; and a light shielding layer having a chromium oxide film (CrO) with a thickness of 30nm on the surface of the synthetic quartz glass_x) (No. 1 Low reflection film), 85nm thick chromium film (Cr) (light-blocking film), and 30nm thick chromium oxide film (CrO)_x) (2 nd low reflection film) is a laminated structure obtained by laminating them in this order.

In the mask production, the light-shielding layer is formed by sputtering on the surface of synthetic quartz glass in the order of a chromium oxide film (1 st low-reflection film), a chromium film (light-shielding film), and a chromium oxide film (2 nd low-reflection film)And then forming. At this time, the deposition of the chromium oxide film (1 st low reflection film), the chromium film (light-shielding film), and the chromium oxide film (2 nd low reflection film) was performed separately using a sputtering apparatus with gas replaced. Further, a chromium oxide film (No. 1 low reflection film) and a chromium oxide film (No. 2 low reflection film) were formed by introducing O into a Cr target mounted in a vacuum chamber₂、N₂、CO₂And a gas, which is formed by reactive sputtering in a vacuum atmosphere. O is increased in the film formation condition of the chromium oxide film (No. 1 low reflection film) as compared with the film formation condition of the low reflection film in the light shielding pattern of the ordinary binary mask₂The ratio of gases. The film formation conditions of the chromium oxide film (2 nd low-reflection film) were the same as those of the low-reflection film in the light-shielding pattern of the normal binary mask. The film formation conditions of the chromium film (light-shielding film) were the same as those of the chromium film in the light-shielding pattern of the general binary mask.

Next, a resist pattern having 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, whereby a light-shielding pattern having a width of 0.1 μm or more and less than 10.0 μm, including a light-shielding pattern having a width of 3.0 μm, is formed from the light-shielding layer. Thus, a large photomask was produced.

Example A2

First, a mask blank is produced, which includes: synthetic quartz glass (light-transmitting substrate) which is precisely polished to have a longitudinal X transverse X film thickness of 700mm X800 mm X8 mm; and a light-shielding layer having a thickness of 180nm and having a laminated structure in which a chromium oxide film (1 st low-reflection film), a chromium film (light-shielding film), and a chromium oxide film (2 nd low-reflection film) are laminated in this order on the surface of the synthetic quartz glass.

In the production of the mask blank, the light-shielding layer is formed by forming a chromium oxide film (1 st low-reflection film), a chromium film (light-shielding film), and a chromium oxide film (2 nd low-reflection film) on the surface of synthetic quartz glass in this order by sputtering. At this time, the deposition of the chromium oxide film (1 st low reflection film), the chromium film, and the chromium oxide film (2 nd low reflection film) was continuously performed without changing the gas of the sputtering apparatus. In addition, a chromium oxide film (No. 1 low reflectance)Film) and chromium oxide film (2 nd low reflection film) in order to mount a Cr target in a vacuum chamber, O was introduced₂、N₂、CO₂And a gas, which is formed by reactive sputtering in a vacuum atmosphere. O is added to the film formation conditions of the chromium oxide film (1 st low reflection film) and the chromium oxide film (2 nd low reflection film) as compared with the film formation conditions of the low reflection film in the light shielding pattern of the ordinary binary mask₂The ratio of gases. The film formation conditions of the chromium film (light-shielding film) were the same as those of the chromium film in the light-shielding pattern of the general binary mask.

Example A3

First, a mask blank is produced, which includes: synthetic quartz glass (light-transmitting substrate) which is precisely polished to have a longitudinal X transverse X film thickness of 700mm X800 mm X8 mm; and a light-shielding layer having a laminated structure in which a chromium oxide film (1 st low-reflection film) having a thickness of 30nm, a chromium film (light-shielding film) having a thickness of 110nm, and a chromium oxide film (2 nd low-reflection film) having a thickness of 30nm are laminated in this order on the surface of the synthetic quartz glass.

In the production of the mask blank, the light-shielding layer is formed by forming a chromium oxide film (1 st low-reflection film), a chromium film (light-shielding film), and a chromium oxide film (2 nd low-reflection film) on the surface of synthetic quartz glass in this order by sputtering. At this time, the deposition of the chromium oxide film (1 st low reflection film), the chromium film (light-shielding film), and the chromium oxide film (2 nd low reflection film) was performed separately using a sputtering apparatus with gas replaced. Further, a chromium oxide film (No. 1 low reflection film) and a chromium oxide film (No. 2 low reflection film) were formed by introducing O into a Cr target mounted in a vacuum chamber₂、N₂、CO₂And a gas, which is formed by reactive sputtering in a vacuum atmosphere. Oxidation compared with the film forming conditions of the low reflection film in the light shielding pattern of the common binary maskIncreasing O in the film formation conditions of the chromium film (No. 1 low reflection film) and the chromium oxide film (No. 2 low reflection film)₂The ratio of gases. Further, the film formation conditions of the chromium film (light-shielding film) lengthen the film formation time as compared with the film formation conditions of the chromium film in the light-shielding pattern of the general binary mask.

[ comparative example A ]

First, a mask blank is produced, which includes: synthetic quartz glass (light-transmitting substrate) which is precisely polished to have a longitudinal X transverse X film thickness of 700mm X800 mm X8 mm; and a light-shielding layer having a laminated structure in which a chromium film (light-shielding film) having a thickness of 85nm and a chromium oxide film (low-reflection film) having a thickness of 30nm are laminated in this order on the surface of the synthetic quartz glass.

In the production of the mask blank, the light-shielding layer is formed by forming a chromium film (light-shielding film) and a chromium oxide film (low-reflection film) in this order on the surface of synthetic quartz glass by sputtering. In this case, the chromium film (light-shielding film) and the chromium oxide film (low-reflection film) are formed separately by using a sputtering apparatus with the gas replaced. In addition, a chromium oxide film (low reflection film) was formed by mounting a Cr target in a vacuum chamber and introducing O₂、N₂、CO₂And a gas, which is formed by reactive sputtering in a vacuum atmosphere. The film formation conditions of the chromium oxide film (low reflection film) were the same as those of the low reflection film in the light shielding pattern of the general binary mask. Further, the film formation conditions of the chromium film were the same as those of the chromium film in the light-shielding pattern of the ordinary binary mask.

[ evaluation results ]

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

The boundary structures of the low reflection films and the light-shielding films of the light-shielding patterns in examples a1 to A3 and comparative example a were observed by SEM (Scanning Electron Microscope). As a result, the Cr content in the boundaries of the light-shielding patterns in examples 1 and 3 varied discontinuously, and the boundaries between the chromium oxide film (1 st low-reflective film) and the chromium film (light-shielding film) and the boundaries between the chromium film (light-shielding film) and the chromium oxide film (2 nd low-reflective film) were clearly defined. In addition, in the boundary of the light-shielding pattern in example 2, the content of Cr continuously changed, and the boundary between the chromium oxide film (1 st low-reflective film) and the chromium film (light-shielding film) and the boundary between the chromium film (light-shielding film) and the chromium oxide film (2 nd low-reflective film) became unclear. In the boundary between the light-shielding patterns in the comparative example, the Cr content varied discontinuously, and the boundary between the chromium film (light-shielding film) and the chromium oxide film (low-reflection film) became clear.

b. Back surface reflectivity, surface reflectivity and Optical Density (OD) of the light-shielding pattern

With respect to the large photomasks of examples a1 to A3 and comparative example a, the back surface reflectance (reflectance of the surface on the synthetic quartz glass side) of the light-shielding pattern with respect to light in the wavelength region of 313nm to 436nm, the surface reflectance (reflectance of the surface on the opposite side from the synthetic quartz glass) of the light-shielding pattern with respect to light in the wavelength region, and the Optical Density (OD) of the light-shielding pattern with respect to light in the wavelength region were measured.

The back surface reflectance and the surface reflectance were measured every 1nm in the wavelength region using a spectrum analyzer (tsukamur electron MCPD 3000). The Optical Density (OD) was measured every 1nm in the wavelength range using an ultraviolet/visible spectrophotometer (Hitachi U-4000). Among the measurement results, the measurement results on the g line (wavelength: 436nm), the h line (wavelength: 405nm), the i line (wavelength: 365nm) and the j line (wavelength: 313nm) are shown in Table 3 below.

Measurement conditions and the like of the above-mentioned spectrum analyzer (tsukamur electron MCPD 3000) are shown in table 1, and measurement conditions of the above-mentioned ultraviolet/visible spectrophotometer (hitachi U-4000) are shown in table 2.

[ Table 1]

[ Table 2]

c. Characteristics of resist pattern

For the purpose of forming a resist pattern of a desired shape, exposure was performed on a resist layer (manufactured by JSR corporation) having a film thickness of 2.5 μm formed on a glass substrate by using the large-sized photomasks of examples a1 to A3 and comparative example a by using the proximity formula (japanese: プロキシ) of the exposure step type (reduction projection type) under the following exposure conditions.

(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 amount: 200mJ/cm²

As properties of the resist patterns formed using the large-sized photomasks of examples a1 to A3 and comparative example a, film thickness variation of uneven portions of the resist pattern with respect to normal portions (hereinafter, sometimes referred to as "uneven portion film thickness variation") was evaluated. Specifically, the rate [% ] of uneven portion film thickness variation in examples a1 to A3 was measured, assuming that the uneven portion film thickness variation in comparative example a was 100%. The results are shown in table 3 below.

In examples a1 to A3, as shown in table 3, the rear surface reflectance was 8% or less for any of g-line, h-line, i-line, and j-line, and the same results were obtained for light of other wavelengths in the wavelength region, although not shown in table 3. In examples a2 and A3, as shown in table 3 above, the surface reflectance was 10% or less for each of g-line, h-line, i-line, and j-line, and the same results were obtained for light of other wavelengths in the wavelength region, although not shown in table 3 above. In example a3, as shown in table 3 above, the Optical Density (OD) was 4.5 or more for any of g-line, h-line, i-line, and j-line, but the same results were obtained for light of other wavelengths in the wavelength region, although not shown in table 3 above. In contrast, in comparative example a, as shown in table 3, the back surface reflectance was greater than 8% for the h-line, i-line, and j-line among the g-line, h-line, i-line, and j-line, the surface reflectance was greater than 10% for any of the g-line, h-line, i-line, and j-line, and the Optical Density (OD) was less than 4.5.

As shown in table 3, in examples a1 to A3, the uneven portion film thickness variation was suppressed as compared with the comparative examples. In examples a2 and A3, the uneven portion film thickness variation was effectively suppressed as compared with example a 1. Further, in example A3, the uneven portion film thickness variation was significantly suppressed as compared with example a 2.

B. Foreign matter reduction by cleaning

Next, the effect of reducing foreign matters by cleaning will be described with reference to examples and comparative examples.

Example B1

A large photomask was fabricated in the same manner as in example a3 described above.

The large photomask thus obtained was cut to a size of 20mm (h) by 30mm (w) by 8mm (d) with a glass cutter. The cut surface was subjected to sputtering treatment (20mA × 12 sec) with platinum and observed with an electron microscope. The electron microscope used was a scanning electron microscope (JSM-6700F, manufactured by japan electronics corporation), the acceleration voltage was set to 5.0kV, the inclination was set to 0 °, the mode was set to SEI (secondary electron imaging, japanese: secondary electron downfeed), the working distance was set to 3.2mm to 3.3mm (Fine adjustment was performed according to the sample height), the number of times of integration was set to 1 (Fine View mode), and the observation magnification was set to × 100K. The measurement site was a portion of a light-shielding pattern having a width of 3.0 μm.

As a result of the measurement, the angle of the side surface of the 1 st low reflection film with respect to the surface of the transparent substrate was 80 °. As described above, the angle is obtained by connecting the position where the side surface of the 1 st low reflection film is in contact with the surface of the transparent substrate and the position where the film thickness of the 1 st low reflection film starts to decrease with a straight line, and measuring the angle between the straight line and the surface.

The large photomask of example B1 was cleaned with pure water for 300 seconds, dried after the cleaning, and the number of foreign matters after the cleaning was measured by a reflection inspection using an appearance inspection machine and a sensitivity with which foreign matters of 1 μm or more could be detected. The measurement value was obtained by measuring a region of 690mm × 790mm excluding the end portion 5mm on the side of the glass substrate 4.

The measurement values are shown in table 4 as ratios obtained when the value of comparative example B described later is assumed to be 100.

Examples B2 to B5

A large photomask having an angle shown in table 4 below was produced by changing the etching conditions of example B1 in a direction to extend the etching time and changing the angle of the side surface of the 1 st low reflection film with respect to the surface of the transparent substrate. The angle was measured in the same manner as in example B1 described above.

These large photomasks were cleaned by the same method as in example B1, and the number of foreign substances was measured in the same manner. The measurement values are shown in table 4 as ratios obtained when the value of comparative example B described later is assumed to be 100.

Comparative example B

A large photomask was produced in the same manner as in comparative example a.

With respect to the obtained large-sized photomask, the angle of the side surface of the 1 st low reflection film with respect to the surface of the transparent substrate was measured by the same method as in example B1.

The obtained large photomask was cleaned in the same manner as in example B1, and the number of foreign substances was measured in the same manner. The results were taken as 100% and are shown in Table 4.

[ Table 4]

Comparative example	Angle (°)	Number of foreign matters
			Example B1	80°	89％
Example B2	60°	77％
			Example B3	52°	28％
Example B4	37°	22％
			Example B5	22°	22％
Comparative example B	70°	100％

As is clear from the results in table 4, the number of foreign matters in the examples was small compared to the comparative examples. The reason for 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, it is found that when the angle is changed, the number of foreign matters is reduced as the angle is smaller, and particularly, the value is greatly changed between example B2 and example B3.

Description of the symbols

100 large photomask

110 light-transmitting substrate

120 light shielding pattern

122 st low reflection film

124 light-shielding film

126 No. 2 Low reflection film

Claims

1. A large 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 a1 st low-reflection film, a light-shielding film, and a2 nd low-reflection film are laminated in this order from the light-transmitting substrate side,

and a reflectance of light facing a wavelength region of 313nm to 436nm on the light transmitting substrate side of the light shielding pattern is 8% or less.

2. The large photomask according to claim 1, wherein a reflectance of light in a wavelength region of 313nm to 436nm facing a side opposite to the light-transmitting substrate of the light-shielding pattern is 10% or less.

3. The large photomask according to claim 1 or 2, wherein the light-shielding film contains chromium, and the 1 st and 2 nd low-reflection films contain chromium oxide.

4. The large photomask according to any one of claims 1 to 3, wherein the light-shielding pattern has an optical density OD of 4.5 or more with respect to light in a wavelength region of 313nm to 436 nm.

5. The large-sized photomask according to claim 4, wherein an inclination angle of the side surface of the light-shielding film with respect to the light-transmissive substrate is 80 degrees or more and 90 degrees or less.

6. The large photomask according to claim 4 or 5, wherein a side surface of the 1 st low-reflection film or a side surface of the 2 nd low-reflection film protrudes in a direction parallel to the surface of the light-transmissive substrate with respect to a side surface of the light-shielding film.

7. The large photomask according to claim 6, wherein both of the side surface of the 1 st low-reflection film and the side surface of the 2 nd low-reflection film protrude in a direction parallel to the surface of the light-transmissive substrate with respect to the side surface of the light-shielding film,

further, the side surface of the 1 st low reflection film protrudes more in a direction parallel to the surface of the translucent substrate than the side surface of the 2 nd low reflection film.

8. The large-sized photomask according to claim 6 or 7, wherein at least a side surface of the 1 st low-reflection film protrudes in a direction parallel to the surface of the light-transmissive substrate with respect to a side surface of the light-shielding film,

further, an angle of the side surface of the 1 st low reflection film with respect to the surface of the transparent substrate is 56 ° or less.

9. The large photomask according to any one of claims 4 to 8, wherein the side surface of the light-shielding film is concave.

10. A large photomask according to any one of claims 1 to 9, which has a division pattern for division exposure, the division pattern being the light shielding pattern.