WO2023120566A1

WO2023120566A1 - Method for manufacturing color filter and photomask for proximity exposure

Info

Publication number: WO2023120566A1
Application number: PCT/JP2022/047055
Authority: WO
Inventors: 冬木今野; 彩子神立; 建也三好; 貴司冨永
Original assignee: 大日本印刷株式会社
Priority date: 2021-12-22
Filing date: 2022-12-21
Publication date: 2023-06-29
Also published as: TW202340761A; JP2023092901A

Abstract

The main purpose of the present invention is to provide a photomask that, using proximity exposure, enables miniaturization of transfer pattern dimensions and an improved taper angle.　The present disclosure provides a photomask for proximity exposure, comprising: a transparent substrate; and a light-blocking film arranged atop the transparent substrate. The light-blocking film has a light-blocking main section (31) in which a substantially polygonal or substantially circular opening is formed, and a light-blocking auxiliary pattern (32) which is arranged inside the opening of the light-blocking main section and which is formed at an interval from the light-blocking main section. The light-blocking film is a phase-shifting film that has a phase-shifting action for shifting the phase relative to exposure light by 180 degrees ± 45 degrees, and that has a 1-10% transmittance of the exposure light.

Description

Photomask for proximity exposure and method for manufacturing color filter

The present disclosure relates to a method for manufacturing a photomask for proximity exposure and a color filter.

Conventionally, in forming a colored layer or the like of a color filter of a liquid crystal display device, a photosensitive resin layer formed on a substrate is subjected to pattern exposure, and after the exposure, the photosensitive resin layer is developed to obtain a desired pattern. A photolithographic method is used to form the In the photolithography method, it is common to irradiate light through a photomask.

At this time, in order to prevent scratches caused by the photomask coming into close contact with the object to be exposed, or to prevent defects from occurring when dust adheres to the photomask, there is a gap between the photomask and the object to be exposed. In many cases, the exposure is performed with a gap provided between the substrates, that is, the proximity exposure is performed. However, when such a gap is provided, there is a problem that a fine pattern cannot be formed in a desired shape due to Fresnel diffraction phenomenon or the like.

In recent years, there are cases where a projection transfer exposure method is used in which a projection lens is provided between the photomask and the substrate to be processed. According to the projection transfer exposure method, since a pattern image can be transferred onto an object to be exposed, a resolution corresponding to the exposure wavelength can be obtained. However, the projection transfer exposure method requires a high-precision lens, which increases the cost of the exposure apparatus. Therefore, there is a demand for a photomask capable of forming a fine pattern in a desired shape by the proximity exposure method.

Therefore, attempts have been made to improve the resolution in the proximity exposure method by devising mask patterns. For example, Patent Literature 1 discloses a technique for miniaturization with a proximity exposure machine using OPC (Optical Proximity Correction). Specifically, a light-transmitting substrate, a light-shielding portion that is provided on the light-transmitting substrate and blocks exposure light, and a region that corresponds to a desired pattern in the light-shielding portion, and the light from the opening of the light-shielding portion is provided. and a main pattern portion provided along a side forming an outline portion of the desired pattern in a peripheral portion of a position corresponding to the desired pattern in the light shielding portion, and out of phase with the light transmitted through the main pattern portion. A photomask is disclosed that includes an auxiliary pattern portion that includes a plurality of in-phase auxiliary patterns formed of openings that transmit aligned in-phase light.

Patent No. 6118996

As the resolution of liquid crystal panels increases, the pixel size also decreases, and the pillars (photospacers) that maintain the cell gap between the color filter and the TFT substrate are required to have finer pattern dimensions and improved taper angles. is required.

There are several ways to improve the transfer dimensions and taper angles of the pillars in the proximity exposure method. For example, there is a method of reducing the exposure gap, but with a large mask, the deflection of the mask cannot be ignored, and the limit of the exposure gap is approaching. There is also a method of changing the resist, but the resolution of the resist is approaching its limit, and even if preparations were made, it would be difficult to obtain approval from the end user for changing the material, and it would be disadvantageous in terms of cost. Furthermore, there is a method of reducing the exposure collimation angle, but if an HRU (High Resolution Unit) using a fly-eye lens or a rod lens is used, the exposure illuminance will decrease, the takt time will increase, and the production efficiency will decrease.

Also, in the case of using a light-shielding film that does not transmit light, as described in Patent Document 1, there is little effect on miniaturization of the transfer pattern dimension. Further, although Patent Document 1 describes that a phase shift film is provided in the opening, the process, the film formation cost, and the manufacturing lead time are lengthened, and the demand for photomasks cannot be met.

The present disclosure has been made in view of the above circumstances, and a main object of the present disclosure is to provide a photomask that enables miniaturization of the transfer pan dimension and improvement of the taper angle by proximity exposure.

An embodiment of the present disclosure is a photomask for proximity exposure, comprising a transparent substrate and a light shielding film disposed on the transparent substrate, the light shielding film having a substantially polygonal or substantially circular shape. A light shielding main portion having an opening formed thereon, and a light shielding auxiliary pattern disposed inside the opening of the light shielding main portion and formed with a gap from the light shielding main portion, wherein the light shielding film is A photomask for proximity exposure, which is a phase shift film having a phase shift action of shifting the phase of exposure light by 180 degrees ± 45 degrees and having a transmittance of 1% or more and 10% or less of the exposure light. do.

In the photomask for proximity exposure according to the present disclosure, the reference photomask intended to form a transfer pattern of the same size of the bottom base is set so that the rising angle of the peak of the light intensity distribution of the light that has passed through is increased. It is preferable that a light shielding auxiliary pattern is arranged.

In the photomask for proximity exposure according to the present disclosure, the diameter of the opening is preferably 10 μm or more and 20 μm or less.

In the photomask for proximity exposure according to the present disclosure, the exposure light is preferably light with a mixed wavelength of j-line (313 nm), i-line (365 nm), h-line (405 nm) and g-line (436 nm). .

One embodiment of the present disclosure is a method for manufacturing a color filter comprising a black matrix, colored pixels, and photospacers on a transparent substrate for a color filter, wherein the above-described proximity exposure photomask is used, A method for manufacturing a color filter is provided, comprising a photospacer forming step of forming a photospacer including a columnar pattern corresponding to the opening in the light shielding main portion.

The present disclosure can provide a photomask that enables miniaturization of the dimension of the transfer pattern and improvement of the taper angle by proximity exposure.

1A and 1B are a plan view and a schematic cross-sectional view showing an example of a photomask for proximity exposure according to the present disclosure; FIG. FIG. 4 is a diagram for explaining light amplitude distribution and light intensity distribution on the imaging plane of a photomask when a phase shift film is used as a light shielding film; It is a figure for demonstrating Fresnel diffraction. 1 is a plan view showing an example of a proximity exposure photomask of the present disclosure; FIG. FIG. 10 is a simulation result showing the relationship between the bottom size of the transfer pattern (columnar pattern) and the slope value in the proximity exposure photomask and the reference photomask of the present disclosure; FIG. 1 is a plan view showing an example of a proximity exposure photomask of the present disclosure; FIG. 1 is a plan view of proximity exposure photomasks of Example 1 and Comparative Example 1, and simulation results thereof. FIG. FIG. 10 is a plan view of proximity exposure photomasks of Example 2 and Comparative Example 2 and their simulation results. FIG. FIG. 10 is a plan view of proximity exposure photomasks of Example 3 and Comparative Example 3 and their simulation results. FIG. These are the results of Examples 1-3 and Comparative Examples 1-3. FIG. 10 is a plan view of a proximity exposure photomask of Example 4 and simulation results thereof. FIG.

Embodiments of the present disclosure will be described below with reference to the drawings and the like. However, the present disclosure can be embodied in many different modes and should not be construed as limited to the description of the embodiments exemplified below. In addition, in order to make the description clearer, the drawings may schematically show the width, thickness, shape, etc. of each part compared to the actual form, but this is only an example and limits the interpretation of the present disclosure. not something to do. In addition, in this specification and each figure, the same reference numerals may be given to the same elements as those described above with respect to the existing figures, and detailed description thereof may be omitted as appropriate.

In this specification, when expressing a mode of arranging another member on top of a certain member, when simply describing “above” or “below”, unless otherwise specified, 2 includes both cases in which another member is arranged directly above or directly below, and cases in which another member is arranged above or below a certain member via another member. In addition, in this specification, when expressing a mode in which another member is arranged on the surface of a certain member, when simply describing “on the surface side” or “on the surface”, unless otherwise specified, It includes both the case of arranging another member directly above or directly below so as to be in contact with it, and the case of arranging another member above or below a certain member via another member.

The photomask for proximity exposure of the present disclosure will be described in detail below. In this specification, the "photomask for proximity exposure" may be simply referred to as a "photomask".

A. Photomask for Proximity Exposure FIG. 1(A) is a schematic plan view showing an example of a photomask of the present disclosure, and FIG. 1(B) is a cross-sectional view taken along the line AA in FIG. As shown in FIG. 1 , a proximity exposure photomask 1 of the present disclosure has a transparent substrate 2 and a light shielding film 3 disposed on the transparent substrate 2 . The light-shielding film 3 has a main light-shielding portion 31 having a substantially polygonal or circular opening O, and an auxiliary light-shielding pattern 32 spaced apart from the main light-shielding portion 31 in the opening. The light shielding film 3 is a phase shift film that shifts the phase of the exposure light that exposes the photomask by 180°±45°, and has a transmittance of 1% or more and 10% or less with respect to the exposure light. Also, in the proximity exposure photomask 1 of the present disclosure shown in FIG.

According to the present disclosure, a phase shift film that shifts the phase of exposure light by 180°±45° is used as the light shielding film, and the auxiliary light shielding pattern is formed inside the opening of the main light shielding portion, whereby a desired light shielding pattern can be obtained. The dimension of the transfer pattern (for example, the columnar pattern corresponding to the opening) can be made finer, and the taper angle can be improved. By using the phase shift film as a light shielding film, the light passing through the phase shift film and the light passing through the transparent region in the opening interfere with each other outside the boundary of the desired transfer pattern. In the vicinity of the center of the desired transfer pattern, the light transmitted through the transparent regions separated by the light shielding auxiliary pattern of the opening interferes with each other and strengthens each other, so that the transmitted light has a steep light intensity. It is presumed that this is to show the distribution. Therefore, according to the proximity exposure photomask of the present disclosure, it is possible to reduce the dimension of the transfer pattern and improve the taper angle. In addition, since the variation in the dimension of the transfer pattern with respect to the exposure gap variation can be reduced, the transfer pattern can be formed with high accuracy even when the photomask is large. Furthermore, since the light intensity increases near the center of the desired transfer pattern, even if an HRU (High Resolution Unit) is used to reduce the exposure collimation angle, the decrease in production efficiency can be suppressed.

FIG. 2A shows the imaging surface of the photomask (specifically, the photosensitive resin layer) when the light-shielding film of the photomask for proximity exposure is a 180-degree phase shift film with a transmittance of 5.2%. 2(B) shows the light intensity distribution on the imaging plane of the photomask. As shown in FIG. 2, the use of the phase shift film allows the light to pass through the phase shift film outside the boundary of the desired transfer pattern (specifically, the position where the light intensity corresponds to the resolution threshold of the resist). It is confirmed that the light L2 that has passed through the opening interferes with the light L1 that has passed through the transparent region in the opening, and the light intensity outside the boundary is weakened.

When the photosensitive resin layer is patterned using the proximity exposure photomask of the present disclosure, the pattern corresponding to the light shielding auxiliary pattern is not resolved, and only the pattern corresponding to the shape of the opening is formed. be done.

As will be described later, the proximity exposure photomask in the present disclosure has a larger rise angle of the peak of the light intensity distribution of the light that has passed through compared to the reference photomask intended to form a transfer pattern of the same bottom size. It is preferable that the light shielding auxiliary pattern is arranged so as to Here, the reference photomask has a light-shielding film that does not substantially transmit light, and has an opening corresponding to the transfer pattern formed on a transparent substrate, and an auxiliary pattern is formed inside the opening. A photomask that has not been

The shape and position of such a light shielding auxiliary pattern can be determined by simulating the light intensity distribution. The light intensity distribution simulation is based on general Fresnel diffraction. Using the following formula (1), the light amplitude E _P at the point P on the substrate is calculated as the integrated value of the spherical wave from each point of the opening (transparent region) of the corresponding proximity exposure photomask. Furthermore, the light intensity I at the point P can be calculated by the following formula (2).

FIG. 3 is a diagram for explaining the calculation of the light intensity distribution at the point P on the substrate 52 according to the following formula (1). 5 is a schematic diagram showing a positional relationship with an arbitrary point P on a substrate 52; FIG. In FIG. 3, the point S is the position on the substrate 52 when the exposure light 53 passing through the point Q travels straight.

Here, in formula (1), k = 2π/λ, E _P is the amplitude of light at point P on the substrate, A is a constant determined by the intensity of incident light, λ is the wavelength of incident light, and δ is the line The angle formed by the segment QS and the line segment QP, r is the distance from the point Q to the point P, and i is the imaginary unit.

I=E _P ×E _P ^* (2)
Here, in Equation (2), E _P ^* is the complex conjugate of E _P . It should be noted that the above calculation is performed by dividing the opening of the photomask for proximity exposure into finite minute sections and using a computer.

For example, when there is one light-shielding assist pattern arranged inside the opening and the shape of the light-shielding assist pattern is a continuous circular ring shape, the diameter A of the opening and the light-shielding assist pattern shown in FIG. If the width B of the pattern 32 and the inner diameter C of the light shielding auxiliary pattern 32 satisfy the following formula, the light intensity at the center of the transfer pattern can be reliably increased, and the boundary of the transfer pattern ( Specifically, the light intensity can be lowered outside the position where the light intensity corresponds to the resolution threshold of the resist.

A×S1+S2−S3≦C≦A×S1+S2+S3 (3)
(In the formula, S1, S2, and S3 are as follows.
S1=(−0.0360×B ² +0.185×B+0.829)
S2=(0.775×B ² −5.97×B−0.777)
S3=(0.0938×B ² −1.31×B+5.26))

FIG. 5 shows the results obtained by simulating the relationship between the bottom size of the transfer pattern (columnar pattern) and the slope value when using the photomask of the present disclosure that satisfies the above formula (3). The transfer conditions were as follows: Collimation half angle: 0.7 degrees, light source of exposure device: 4-wavelength mixed light source of j-line (313 nm), i-line (365 nm), h-line (405 nm), and g-line (436 nm), exposure gap : 200 μm. Similarly, for the reference photomask, the relationship between the bottom size of the columnar pattern and the slope value was obtained by simulation.

As shown in FIG. 5, with the reference photomask, when the bottom size (μm) of the transfer pattern is small, particularly when the bottom size of the transfer pattern is 10 μm or less, it can be confirmed that the slope value significantly decreases. On the other hand, it was confirmed that the photomask of the present disclosure has a higher slope value than the reference photomask at all points that satisfy the above formula (3). The slope value is the slope of the tangential line at the resist resolution threshold in the simulation result of the light intensity distribution.

Thus, when the photomask of the present disclosure is used, the slope value becomes high, that is, the taper angle of the transfer pattern becomes nearly vertical. The taper angle refers to the angle between the side surface of a layer having a tapered shape and the bottom surface of the layer.

In addition, depending on the application of the transfer pattern, the proximity exposure photomask in the present disclosure does not necessarily have a peak of the light intensity distribution of the light that has passed through, compared to the reference photomask intended for the transfer pattern of the same bottom size. The auxiliary light shielding pattern does not have to be arranged so that the rising angle is large.

Each configuration of the photomask of the present disclosure will be described in detail below.

1. Light-Shielding Main Portion The light-shielding main portion of the photomask in the present disclosure is arranged on a transparent base material and has a substantially polygonal or substantially circular opening. The opening is a region corresponding to a desired transfer pattern (design pattern). The number of openings in the light shielding main portion is not particularly limited, and may be one or more.

The shape of the opening is appropriately selected according to the type and application of the proximity exposure photomask. In the present disclosure, the term “substantially circular” refers to a circular shape (perfect circle) and an elliptical shape whose maximum diameter is greater than 1 and less than or equal to 3.0 when the minimum diameter is 1. Further, a substantially polygonal shape means a regular polygon and a straight line drawn from each corner passing through the center. Polygons within the range of 0 or less are defined.

In the present invention, the diameter of the opening is, for example, 10 μm or more. On the other hand, it is, for example, 20 μm or less, preferably 15 μm or less. A specific range is, for example, about 10 μm or more and 20 μm or less, and particularly preferably about 10 μm or more and 15 μm or less. When the opening is substantially polygonal, the diameter of the opening is defined as the length of a straight line drawn from each corner and passing through the center. Moreover, in the case of an ellipse or a polygon other than a regular polygon, the minimum diameter is preferably within the above range.

2. Light-Shielding Auxiliary Pattern The light-shielding auxiliary pattern of the photomask for proximity exposure in the present disclosure is formed inside the opening of the light-shielding main portion with a gap from the light-shielding main portion. Such a light-shielding auxiliary pattern is such that, when exposed under the same conditions to a reference photomask intended for a transfer pattern of the same bottom size, the rising angle of the peak of the light intensity distribution of the light that passes through is increased. It is preferable that the width, size, and distance from the light shielding main portion are arranged. The same condition means that the exposure wavelength, exposure gap, and exposure collimation angle are the same.

The light shielding auxiliary pattern arranged inside the opening may be one or two or more.

A photomask for proximity exposure when there is one light shielding auxiliary pattern arranged inside the opening will be described. As shown in FIG. 1, the auxiliary light-shielding pattern 32 has an outer transparent region 42 inside the auxiliary light-shielding pattern 32 and a gap between the auxiliary light-shielding pattern 32 and the main light-shielding portion 31 in the opening O. It is preferable that the light shielding auxiliary pattern is arranged so that the light transmitted through the transparent region 41 interferes to increase the light intensity in the vicinity of the center of the transfer pattern.

A photomask for proximity exposure when there are two light shielding auxiliary patterns arranged inside the opening will be described. In the photomask for proximity exposure shown in FIG. 6, a first light-shielding auxiliary pattern 32a and a second light-shielding auxiliary pattern 32b are formed inside the opening O from the light-shielding main portion 31 side. A transparent area 43 inside the second auxiliary light-shielding pattern 32b, a transparent area 42 which is the gap between the first auxiliary light-shielding pattern 32a and the second auxiliary light-shielding pattern 32b, the first auxiliary light-shielding pattern 32a, and the light-shielding pattern. The second light-shielding assist pattern and the first light-shielding assist pattern are arranged so that the light passing through the transparent region 41, which is the gap with the main portion 31, increases the light intensity in the vicinity of the center of the transfer pattern due to interference. is preferred.

The specific size and width of the auxiliary light-shielding pattern, and the distance between the main light-shielding portion and the auxiliary light-shielding pattern can be determined by simulating the light intensity distribution based on the Fresnel diffraction described above.

Specific shapes of the light shielding auxiliary pattern include various shapes such as a circular ring shape and a polygonal ring shape. Further, the external shape of the auxiliary light shielding pattern may or may not be similar to the shape of the opening of the light shielding main portion, but is preferably similar. This is because the shape of the transfer pattern is stabilized. Further, the shape of the opening of the auxiliary light shielding pattern may be the same as the shape of the opening of the light shielding main portion, but it does not have to be the same shape.

Further, it is preferable that the center of the light shielding auxiliary pattern and the opening in the light shielding main portion are concentric. Here, the fact that the center of the auxiliary light-shielding pattern is concentric with the center of the opening of the main light-shielding portion means that the center of the auxiliary light-shielding pattern is within a circle with a radius of 1 μm from the center of the opening of the main light-shielding portion. .

The light shielding auxiliary pattern may be formed continuously or may be formed discontinuously.

When there is one light-shielding auxiliary pattern arranged inside the opening, its width ((B) in FIG. 4) is preferably 0.5 μm or more, and more preferably 0.8 μm or more. On the other hand, 8.0 μm or less is preferable, and 7.0 μm or less is particularly preferable. As a specific range, about 0.5 μm or more and 8 μm or less is preferable, and about 0.8 μm or more and 7.0 μm or less is particularly preferable. This is because if the width of the light-shielding assist pattern is less than the above range, the desired effect of the light-shielding assist pattern cannot be obtained. This is because there is a possibility that the image will be resolved at the time.

In addition, the inner diameter of the light shielding auxiliary pattern ((C) in FIG. 4) is preferably 1 μm or more, more preferably 2 μm or more. On the other hand, 19 μm or less is preferable, and 11 μm or less is particularly preferable. A specific range is preferably about 1 μm or more and 19 μm or less, more preferably about 2 μm or more and 11 μm or less.

Further, the width of the gap (transparent region) between the main light-shielding portion and the auxiliary light-shielding pattern is preferably 1 μm or more, more preferably 1.5 μm or more. On the other hand, 4 μm or less is preferable, and 2.0 μm or less is particularly preferable. As a specific range, about 1 μm to 4 μm is preferable, and about 1.5 μm to 2.0 μm is particularly preferable.

Further, when there are two auxiliary light-shielding patterns (first and second auxiliary light-shielding patterns) arranged inside the opening, the widths of the first and second auxiliary light-shielding patterns are 0.5. 8 μm or more is preferable. On the other hand, 3.0 μm or less is preferable, and 2.0 μm or less is particularly preferable. As a specific range, about 0.8 μm to 3.0 μm is preferable, and about 0.8 μm to 2.0 μm is particularly preferable.

Also, the width of the gap (transparent region) between the main light-shielding portion and the first auxiliary light-shielding pattern is preferably 1 μm or more. On the other hand, 4 μm or less is preferable, and 2.0 μm or less is particularly preferable. As a specific range, about 1 μm to 4 μm is preferable, and about 1.0 μm to 2.0 μm is particularly preferable.

Also, the width of the gap (transparent region) between the first light-shielding auxiliary pattern and the second light-shielding auxiliary pattern is preferably 1.0 μm or more. On the other hand, 4.0 μm or less is preferable, and 2.0 μm or less is particularly preferable. As a specific range, about 1.0 μm or more and 4.0 μm or less is preferable, and about 1.0 μm or more and 2.0 μm or less is particularly preferable.

Moreover, it is preferable that the thickness of the auxiliary light-shielding pattern is approximately the same as the thickness of the main light-shielding portion.
This is because, as described above, the auxiliary light-shielding pattern and the main light-shielding portion can be collectively formed in the process of manufacturing the photomask for proximity exposure according to the present invention.

3. Light-Shielding Film The light-shielding film in the present disclosure includes the light-shielding main portion and the light-shielding auxiliary pattern. In the present disclosure, the light-shielding film has a phase shift effect of shifting the phase of the exposure light transmitted through the transparent region by 180 degrees ± 45 degrees, and the exposure light is transmitted by 1% or more, preferably 4% or more. have a rate. On the other hand, it has a transmittance of 10% or less, preferably 7% or less. A specific range of the transmittance is 1% or more and 10% or less, preferably 4% or more and 7% or less.
In the present disclosure, as exposure light, any of j-line (313 nm), i-line (365 nm), h-line (405 nm) and g-line (436 nm), or mixed wavelength light including these wavelength ranges. can do.

By using a light-shielding film having such a phase-shifting action, the light passing therethrough exhibits a steep light intensity distribution, as described above. The transmittance can be measured using the transmittance of a transparent substrate, which will be described later, as a reference (100%). An ultraviolet/visible spectrophotometer (for example, Hitachi U-4000) can be used for the measurement of the average transmittance. Table 1 summarizes the measurement conditions of the ultraviolet/visible spectrophotometer (Hitachi U-4000).

In addition, the transmittance in the case of a mixed wavelength of j-line (313 nm), i-line (365 nm), h-line (405 nm) and g-line (436 nm) is the value of the wavelength with the highest transmittance among the mixed wavelengths. be.

The configuration of the light-shielding film may be a single-layer film formed by selecting a material that provides the above transmittance with a film thickness that shifts the phase of the exposure light by 180°±45°. In addition, a phase adjustment layer made of a material with high transmittance that mainly shifts the phase by 180 degrees ± 45 degrees and a transmittance adjustment layer made of a material with low transmittance that mainly determines the transmittance. is also mentioned.

When the light-shielding film is composed of a single layer, the refractive index n is high (usually 1.5 or more), and the thickness d that shifts the phase of the exposure light of wavelength λ by 180° ± 45° is 1% to 10%. Select a material that provides the desired transmittance within the range. Materials for such a semitransparent phase shift film composed of a single layer include chromium oxynitride (CrON), molybdenum silicide nitride (MoSiN), molybdenum silicide oxynitride (MoSiON), silicon oxynitride (SiON), Titanium oxynitride (TiON) can be exemplified, and the transmittance is adjusted by changing the content of oxygen and nitrogen.

The light-shielding film is required to have a film thickness that shifts the phase of the exposure light by 180°±45°. There is a relationship of Φ=2π(n−1)d/λ between the phase differences Φ generated through the pattern, and the phase differences are inverted because Φ=π. The film thickness d is λ/2(n−1). The phase difference is not limited to 180 degrees, and a sufficient phase shift effect can be obtained as long as it is within the range of 180 degrees±45 degrees.

When the light-shielding film is composed of two layers, first, a material with a high refractive index at the exposure wavelength and a high light transmittance is selected as a material for the phase adjustment layer, and a layer for inverting the phase is selected. A material having a low transmittance at the exposure wavelength is selected, the phase of the exposure light is inverted for the entire two-layer film, and each film thickness is adjusted so that the transmittance has a desired value. Chromium oxynitride (CrON), chromium oxyfluoride (CrFO), silicon oxynitride (SiON), molybdenum silicide oxynitride (MoSiON), and titanium oxynitride (TiON) are used as materials for the phase adjustment layer. Chromium (Cr), chromium nitride (CrN), tantalum (Ta), and titanium (Ti) are used as the index adjusting layer. A specific combination of materials for forming the semitransparent phase shift film in two layers is a combination of chromium oxynitride (CrON) for the phase adjustment layer and chromium nitride (CrN) for the transmittance adjustment layer, and oxidation of the phase adjustment layer. A combination of chrome fucca (CrFO) and chromium nitride (CrN) for the transmittance adjustment layer, molybdenum oxynitride silicide (MoSiON) for the phase adjustment layer, and molybdenum oxynitride silicide (MoSiON) having a smaller oxygen ratio than the phase adjustment layer for the transmittance adjustment layer. ) can be exemplified.

Specifically, in the present disclosure, a single-layer chromium oxynitride (CrON) film can be exemplified.

4. Transparent Substrate The transparent substrate used in the present invention is not particularly limited as long as it can form the light shielding main portion and the light shielding auxiliary pattern, and transparent substrates used in general photomasks can be used. can. Examples of transparent substrates include optically polished low-expansion glass such as borosilicate glass and aluminoborosilicate glass, quartz glass, synthetic quartz glass, Pyrex (registered trademark) glass, soda lime glass, and white sapphire. A transparent rigid material, or a transparent flexible material such as a transparent resin film or an optical resin film can be used. Among them, quartz glass is a material with a small coefficient of thermal expansion, and is excellent in dimensional stability and properties in high-temperature heat treatment.

5. Photomask for Proximity Exposure Next, a photomask for proximity exposure according to the present disclosure will be described. The photomask for proximity exposure of the present invention is not particularly limited as long as a light-shielding film having the light-shielding main portion and the light-shielding auxiliary pattern is formed on the transparent substrate.

A photomask for proximity exposure according to the present disclosure generally includes a light shielding main portion in which one or more openings are formed, and one or more light shielding auxiliary patterns described above disposed inside the openings. have The plurality of openings formed in the light-shielding main portion of the proximity exposure photomask of the present disclosure may have the same shape and size, or may have different sizes. Further, the auxiliary light shielding patterns arranged inside the respective openings may have the same shape, the same size, and the arrangement positions in the openings, or may be different from each other.

Further, in the present disclosure, at least one of the plurality of openings formed in the light-shielding main portion of the photomask for proximity exposure may have the above-described light-shielding auxiliary pattern disposed inside. It may have openings that are not located inside.

In recent years, liquid crystal panels have become higher definition and thinner, and the touch panel function has been added. A color filter or the like including a second photospacer that is lower (thinner) than the photospacer has been developed.

The proximity exposure photomask in the present disclosure includes a plurality of combinations of openings and light shielding auxiliary patterns, or openings in which light shielding auxiliary patterns are not arranged in addition to openings in which light shielding auxiliary patterns are arranged. By including , it is possible to form columnar patterns (for example, photospacers) with different heights (thicknesses) or different dimensions (diameters) with one mask.

The photomask for proximity exposure of the present invention does not particularly limit the exposure light source, but the exposure light source is, for example, a mercury lamp, and the exposure light is j-line (313 nm), i-line (365 nm), h-line ( 405 nm), g-line (436 nm), or mixed wavelengths including these wavelength ranges. The use of the above-described mixed wavelength exposure light has the advantage that the exposure energy applied to the photosensitive resin layer in the transparent region can be increased and the exposure time can be shortened.

Also, the photomask for proximity exposure of the present invention is suitably used when forming a fine columnar pattern corresponding to the opening using a negative resist. Specifically, it is particularly useful when forming a photospacer for a color filter for a liquid crystal display device, which will be described later. However, it is not limited to this case, and can also be used when forming fine holes corresponding to the openings using a positive resist.

B. A method for manufacturing a color filter A method for manufacturing a color filter according to the present disclosure is a method for manufacturing a color filter including a black matrix, colored pixels, and photospacers on a transparent substrate for a color filter. A method for manufacturing a color filter, comprising a photospacer forming step of forming a photospacer including a columnar pattern corresponding to the opening in the light shielding main portion using an exposure photomask.

(1) Photospacer formation step The photospacer formation step in the present disclosure is a step of forming a photospacer including a columnar pattern corresponding to the opening using the proximity exposure photomask. Specifically, a step of exposing and developing a photospacer-forming composition containing a negative photosensitive resin to form a photospacer including a columnar pattern formed in a pattern similar to that of the openings. be able to.

The photospacer-forming composition used in this step is preferably less sensitive to light in regions other than the transfer pattern (columnar pattern), and the resolution threshold of the resist is equal to or higher than the intensity of light transmitted through the phase shift film. things are preferred.

The shape of the above-mentioned columnar pattern formed by this process is usually a columnar shape or a polygonal columnar shape. The bottom dimension (diameter) of the columnar pattern is, for example, 17 μm or less, preferably 12 μm or less. On the other hand, 5 µm or more is preferable, and 8 µm or more is particularly preferable. As a specific range, it is preferably in the range of 5 μm or more and 17 μm or less, particularly in the range of 8 μm or more and 12 μm or less.

In addition, the height of the columnar pattern formed by this step is usually 1.0 μm or more, preferably 1.5 μm or more. On the other hand, it is usually 4.0 μm or less, preferably 3.0 μm or less. A specific range is generally about 1.0 μm to 4.0 μm, preferably about 1.5 μm to 3.0 μm.

Further, by using the photomask for proximity exposure of the present disclosure, a color filter including a first photospacer and a second photospacer lower than the first photospacer can be manufactured. In this case, the transfer pattern corresponding to the openings of the proximity exposure photomask in the present disclosure may be at least one of the first photospacer and the second photospacer.

Specifically, in this step, a negative resist composition for forming a photospacer is applied onto a transparent substrate for a color filter on which a black matrix and colored pixels are formed, dried, and exposed through a mask. The photospacer can be patterned by curing the exposed portion with an alkali developer and developing with an alkaline developer.

The photospacer is preferably formed above the non-display area, that is, the black matrix.

(2) Other steps The method for producing a color filter according to the present embodiment is not particularly limited as long as it includes the photospacer forming step. It may have necessary steps such as a colored layer forming step of forming a layer and a transparent electrode layer forming step of forming a transparent electrode layer on the colored layer. Each of these steps can be the same as each step in a general color filter manufacturing method.

It should be noted that the present disclosure is not limited to the above embodiments. The above embodiment is an example, and any device that has substantially the same configuration as the technical idea described in the claims of the present disclosure and achieves the same effect is the present invention. It is included in the technical scope of the disclosure.

Examples and comparative examples are shown below to describe the present disclosure in more detail.

(Comparative Example 1, Example 1)
For the photomasks of Comparative Example 1 and Example 1, which were set as follows, the difference in bottom dimension size at the same light intensity was determined by simulation.
As shown in FIG. 7A, a binary mask having a light-shielding film with an OD value of 3 or more and an opening with a diameter of 13 μm formed on a transparent substrate made of quartz glass was used as a photomask of Comparative Example 1.
As shown in FIG. 7B, a light-shielding main portion 31 having a transmittance of 5.2% and an opening having a diameter of 14 μm, which is made of a 180-degree phase shift film, is formed on a transparent substrate made of quartz glass, and an opening. A photomask of Example 1 was used, in which a ring-shaped light shielding auxiliary pattern 32 with a width of 2 μm and an inner diameter of 2 μm was formed inside the portion.

An object to be exposed at a distance of 200 μm as an exposure gap G is subjected to proximity exposure so that the maximum light intensity is almost the same as Comparative Example 1: 1.87 and Example 1: 1.83. The light intensity distribution formed above was obtained by simulation. The results are shown in FIG. 7(C). The above maximum light intensity is a value when the incident light intensity is 1. Other transfer conditions are Collimation half angle: 0.7 degrees, exposure wavelength: j-line (313 nm), i-line (365 nm). , h-line (405 nm), and g-line (436 nm).

From FIG. 7C, the bottom size of the transfer pattern obtained in Comparative Example 1 (Y in FIG. 7) is 12.61 μm, and the bottom size of the transfer pattern obtained in Example 1 (X in FIG. 7) is 12.61 μm. was calculated to be 9.86 μm (FIG. 10(A)). The slope value was 0.093 in Comparative Example 1 and 0.170 in Example 1, and it was confirmed that in Example 1, the dimension of the transfer pattern was reduced and the taper angle was also improved.

(Comparative Example 2, Example 2)
For the photomasks of Comparative Example 2 and Example 2, which were set as follows, the difference in the taper angle at the same bottom dimension size was determined by simulation.
A binary mask having a light-shielding film (OD value: greater than 3) with an opening of 8 μm in diameter formed on a transparent substrate made of quartz glass as shown in FIG. 8A was used as a photomask of Comparative Example 2.
As shown in FIG. 8B, a light-shielding main portion 31 having a transmittance of 5.2% and an opening having a diameter of 14 μm, which is made of a 180-degree phase shift film, is formed on a transparent substrate made of quartz glass, and an opening. The photomask of Example 2 is provided with a ring-shaped light shielding auxiliary pattern 32a having a width of 1 μm and an inner diameter of 8 μm and a ring-shaped light shielding auxiliary pattern 32b having a width of 1 μm and an inner diameter of 2 μm. and

Proximity exposure was performed on an object to be exposed at a distance of 200 μm as the exposure gap G so that the bottom size of the obtained transfer pattern was almost the same as Comparative Example 2: 9.38 μm and Example 2: 9.28 μm. , the light intensity distribution formed on the exposed body was obtained by simulation. The results are shown in FIG. 8(C). The transfer conditions were: Collimation half angle: 0.7 degrees, Exposure wavelength: Light with a mixed wavelength of j-line (313 nm), i-line (365 nm), h-line (405 nm) and g-line (436 nm).

From FIG. 8(C), the maximum light intensity obtained in Comparative Example 2 was 0.39, and the maximum light intensity obtained in Example 2 was 1.26. Moreover, the slope value was 0.05 in Comparative Example 2 and 0.165 in Example 2, and it was confirmed that the taper angle was also improved (FIG. 10(B)).

(Example 3)
As shown in FIG. 9B, a light-shielding main portion 31 having a transmittance of 5.2% and an opening having a diameter of 17 μm, which is made of a 180-degree phase shift film, is formed on a transparent substrate made of quartz glass, and an opening. A photomask of Example 3 was used in which a ring-shaped light shielding auxiliary pattern 32 with a width of 1 μm and an inner diameter of 13 μm was arranged inside the portion. A light intensity distribution was obtained by simulation when proximity exposure was performed with an exposure gap G of 200 μm and a transfer pattern dimension of 13.2 μm. The maximum light intensity in Example 3 was 2.011. The transfer conditions were: Collimation half angle: 0.7 degrees, Exposure wavelength: Light with a mixed wavelength of j-line (313 nm), i-line (365 nm), h-line (405 nm) and g-line (436 nm).
Further, the transfer pattern dimension was obtained by simulation when the exposure gap was changed to 180 μm and the proximity exposure was performed under the above transfer conditions. The change rate (ΔCD/ΔGap) of the transfer pattern dimension CD due to changing the exposure gap from 200 μm to 180 μm was calculated by the following formula and found to be 0.003.
ΔCD/ΔGap=(CD ₂₀₀ −CD ₁₈₀ )/(200 μm−180 μm)
In the formula, CD ₂₀₀ is the dimension of the transferred pattern when the exposure gap is 200 μm, and CD ₁₈₀ is the dimension of the transferred pattern when the exposure gap is 180 μm.

(Comparative Example 3)
As shown in FIG. 9A, the photomask of Comparative Example 3 was a binary mask in which a light-shielding film having an opening with a diameter of 14 μm and an OD value of 3 or more was formed on a transparent substrate made of quartz glass. Proximity exposure was performed on the photomask of Comparative Example 3 under the same transfer conditions as in Example 3 so that the exposure gap G was 200 μm and the size of the bottom of the transfer pattern was 13.3 μm, which was almost the same as in Example 3. was obtained by simulation. The results are shown in FIG. 9(C). The maximum light intensity at an exposure gap of 200 μm in Comparative Example 3 was 2.128. FIG. 9C shows the light intensity distribution obtained by simulation when only the exposure gap is changed to 180 μm. Also, the change rate (ΔCD/ΔGap) of the transfer pattern dimension CD due to changing the exposure gap from 200 μm to 180 μm was calculated by the above formula. ΔCD/ΔGap was 0.027.
It was confirmed that in Example 3, compared with Comparative Example 3, variations in the transfer pattern dimension caused by variations in the exposure gap were smaller (FIG. 10(C)).

(Example 4)
For proximity exposure photomasks having two types of opening patterns for the first photospacer and the second photospacer shown in FIGS. The light intensity distribution was obtained by simulation. The results are shown in FIG. 11(C). The light-shielding film 3 is a 180-degree phase shift film with a transmittance of 5.2%. Mixed wavelength light of line (405 nm) and g line (436 nm), exposure gap: 200 μm. The opening pattern of FIG. 11(A) and the opening pattern of FIG. 11(B) have the same bottom dimension of 11.8 μm, and different maximum light intensities were obtained ((A): 2.62, (B): 0.88). From the above, it was confirmed that by combining different opening patterns, it is possible to form columnar photospacers of different heights and sizes with one mask.

The present disclosure provides, for example, the following inventions.

[1]
A photomask for proximity exposure,
Having a transparent substrate and a light shielding film disposed on the transparent substrate,
The light shielding film includes a light shielding main portion having a substantially polygonal or circular opening, and a light shielding main portion disposed inside the opening of the light shielding main portion and spaced apart from the main light shielding portion. and a light shielding auxiliary pattern,
For proximity exposure, the light shielding film is a phase shift film having a phase shift action of shifting the phase of the exposure light by 180 degrees ± 45 degrees and having a transmittance of the exposure light of 1% or more and 10% or less. photo mask.
[2]
In the proximity exposure photomask, the light shielding assist pattern is arranged so that the rising angle of the peak of the light intensity distribution of the light that passes through is larger than that of the reference photomask intended to form a transfer pattern of the same bottom size. is disposed, the photomask for proximity exposure according to [1].
[3]
The photomask for proximity exposure according to [1] or [2], wherein the opening has a diameter of 10 μm or more and 20 μm or less.
[4]
The exposure light according to any one of [1] to [3], wherein the exposure light is light of a mixed wavelength of j-line (313 nm), i-line (365 nm), h-line (405 nm) and g-line (436 nm). Photomask for proximity exposure.
[5]
A method for manufacturing a color filter comprising a black matrix, colored pixels, and photospacers on a transparent substrate for a color filter, comprising:
Using the proximity exposure photomask according to any one of [1] to [4], a photospacer forming step of forming a photospacer including a columnar pattern corresponding to the opening in the light shielding main portion. A method for manufacturing a color filter, characterized by:

DESCRIPTION OF SYMBOLS 1... Photomask for proximity exposure 2... Transparent substrate 3... Light-shielding film 31... Light-shielding main part 32... Light-shielding auxiliary pattern

Claims

A photomask for proximity exposure,
Having a transparent substrate and a light shielding film disposed on the transparent substrate,
The light shielding film includes a light shielding main portion having a substantially polygonal or circular opening, and a light shielding main portion disposed inside the opening of the light shielding main portion and spaced apart from the main light shielding portion. and a light shielding auxiliary pattern,
For proximity exposure, the light shielding film is a phase shift film having a phase shift action of shifting the phase of the exposure light by 180 degrees ± 45 degrees and having a transmittance of the exposure light of 1% or more and 10% or less. photomask.
In the proximity exposure photomask, the light shielding assist pattern is arranged so that the rising angle of the peak of the light intensity distribution of the light that passes through is larger than that of the reference photomask intended to form a transfer pattern of the same bottom size. 2. The photomask for proximity exposure according to claim 1, wherein is arranged.
The photomask for proximity exposure according to claim 1, wherein the opening has a diameter of 10 µm or more and 20 µm or less.
The photomask for proximity exposure according to claim 1, wherein the exposure light is light of a mixed wavelength of j-line (313 nm), i-line (365 nm), h-line (405 nm) and g-line (436 nm).
A method for manufacturing a color filter comprising a black matrix, colored pixels, and photospacers on a transparent substrate for a color filter, comprising:
A photospacer forming step of forming a photospacer including a columnar pattern corresponding to the opening in the light shielding main portion, using the proximity exposure photomask according to any one of claims 1 to 4. A method for manufacturing a color filter, comprising: