Photomask for proximity exposure and method for manufacturing color filters

Abstract

To provide a photomask that enables a finer sized transfer pattern and an improved taper angle through a proximity exposure.SOLUTION: A photomask includes a transparent substrate 2 and a light-shielding film 3 arranged on the transparent substrate. The light-shielding film includes: a light-shielding primary part 31 with a substantially polygonal or substantially circular opening O formed therein; and a light-shielding auxiliary pattern 32 arranged inside the opening of the light-shielding primary part and formed with an interval from the light-shielding primary part. The light-shielding film is a phase shift film having a phase shift effect that shifts a phase by 180±45 degrees against exposure light, and having a transmission rate of the exposure light of 1% to 10%.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a photomask for proximity exposure and a method for manufacturing a color filter. [Background technology]

[0002] Conventionally, photolithography has been used to form colored layers of color filters for liquid crystal displays, in which a photosensitive resin layer formed on a substrate is exposed to light in a pattern and then developed after the exposure to form a desired pattern. In photolithography, light is generally irradiated through a photomask.

[0003] In this case, in order to prevent scratches caused by the photomask being in close contact with the object to be exposed, or to prevent defects caused by dust adhering to the photomask, a gap is often provided between the photomask and the object to be exposed, i.e., proximity exposure is performed. However, when such a gap is provided, there is a problem that it is not possible to form a fine pattern in the desired shape due to the Fresnel diffraction phenomenon and the like.

[0004] In recent years, the projection transfer exposure method, in which a projection lens is placed between the photomask and the substrate to be processed, has been used in some cases. Projection transfer exposure allows a pattern image to be transferred onto the object to be exposed, achieving a resolution equivalent to the exposure wavelength. However, projection transfer exposure requires high-precision lenses, which increases the cost of the exposure equipment. Therefore, there is a demand for photomasks that can form fine patterns into the desired shape using proximity exposure methods.

[0005] Therefore, attempts have been made to improve the resolution in the proximity exposure method by modifying the mask pattern. For example, Patent Document 1 discloses a technology for achieving miniaturization using a proximity exposure machine using OPC (Optical Proximity Correction). Specifically, the patent document discloses a photomask including: a light-transmitting substrate; a light-shielding portion provided on the light-transmitting substrate for blocking exposure light; a main pattern portion provided in a region of the light-shielding portion corresponding to a desired pattern and consisting of openings in the light-shielding portion; and an auxiliary pattern portion including a plurality of in-phase auxiliary patterns formed of openings that transmit light in phase with light transmitted through the main pattern portion and that is provided in a peripheral portion of the light-shielding portion corresponding to the desired pattern and along a side that constitutes a contour of the desired pattern. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 6118996 Summary of the Invention [Problem to be solved by the invention]

[0007] As the resolution of LCD panels increases, pixel size is also decreasing, and there is a demand for finer pattern dimensions and improved taper angles for the pillars (photospacers) that maintain the cell gap between the color filter and TFT substrate.

[0008] There are several ways to improve the pillar transfer dimensions and taper angle using proximity exposure. For example, reducing the exposure gap is one option, but with large masks, mask deflection cannot be ignored and the exposure gap is approaching its limit. Another option is to change the resist, but the resist resolution is also approaching its limit. Even if the solution were ready, it would be difficult to obtain end-user approval for the material change, and it would be cost-inefficient. Another option is to reduce the exposure collimation angle, but using a high-resolution unit (HRU) with a fly-eye lens or rod lens reduces the exposure illuminance, extending the takt time and reducing production efficiency.

[0009] Furthermore, using a light-blocking film that does not transmit light, as described in Patent Document 1, is not very effective in miniaturizing the dimensions of the transferred pattern. Furthermore, Patent Document 1 also describes providing a phase shift film in the opening, but this increases the process, film formation costs, and manufacturing lead time, making it impossible to meet the demand for photomasks.

[0010] The present disclosure has been made in consideration of the above circumstances, and has as its main object to provide a photomask that enables the dimensions of transfer patterns to be miniaturized and the taper angle to be improved by proximity exposure. [Means for solving the problem]

[0011] One embodiment of the present disclosure provides a photomask for proximity exposure, the photomask having a transparent substrate and a light-shielding film disposed on the transparent substrate, the light-shielding film having a main light-shielding portion with an approximately polygonal or approximately circular opening formed therein, and a light-shielding auxiliary pattern disposed inside the opening of the main light-shielding portion and formed at a distance from the main light-shielding portion, the light-shielding film having a phase shift effect of shifting the phase of exposure light by 180 degrees ±45 degrees, and being a phase shift film having a transmittance of the exposure light of 1% or more and 10% or less.

[0012] In the proximity exposure photomask of the present disclosure, it is preferable that the above-mentioned shading auxiliary pattern is arranged so that the rise angle of the peak of the light intensity distribution of the passed light is larger than that of a reference photomask intended to form a transfer pattern of the same bottom size.

[0013] In the proximity exposure photomask of the present disclosure, the diameter of the opening is preferably 10 μm or more and 20 μm or less.

[0014] In the proximity exposure photomask of 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).

[0015] One embodiment of the present disclosure provides a method for manufacturing a color filter comprising a black matrix, colored pixels, and photospacers on a transparent substrate for a color filter, the method comprising a photospacer formation step of forming photospacers including a columnar pattern corresponding to the openings in the main light-shielding portion using the above-mentioned proximity exposure photomask. [Effects of the Invention]

[0016] The present disclosure can provide a photomask that enables the dimensions of a transferred pattern to be miniaturized and the taper angle to be improved by proximity exposure. [Brief explanation of the drawings]

[0017] [Figure 1] 1A and 1B are a plan view and a schematic cross-sectional view showing an example of a proximity exposure photomask according to the present disclosure. [Figure 2] 10A and 10B are diagrams illustrating the light amplitude distribution and the light intensity distribution on the imaging plane of a photomask when a phase shift film is used as a light-shielding film. [Figure 3] FIG. 1 is a diagram illustrating Fresnel diffraction. [Figure 4]FIG. 1 is a plan view showing an example of a proximity exposure photomask according to the present disclosure. [Figure 5] 10 is a simulation result showing the relationship between the bottom size and slope value of a transferred pattern (columnar pattern) for a proximity exposure photomask according to the present disclosure and a reference photomask. [Figure 6] FIG. 1 is a plan view showing an example of a proximity exposure photomask according to the present disclosure. [Figure 7] 1A and 1B are plan views of proximity exposure photomasks according to Example 1 and Comparative Example 1, and simulation results thereof. [Figure 8] 10A and 10B are plan views of proximity exposure photomasks according to Example 2 and Comparative Example 2, and simulation results thereof. [Figure 9] 10A and 10B are plan views of proximity exposure photomasks according to Example 3 and Comparative Example 3, and simulation results thereof. [Figure 10] The results are for Examples 1 to 3 and Comparative Examples 1 to 3. [Figure 11] 10A and 10B are plan views of a proximity exposure photomask according to Example 4 and simulation results thereof. DETAILED DESCRIPTION OF THE INVENTION

[0018] Embodiments of the present disclosure will be described below with reference to the drawings and the like. However, the present disclosure can be implemented in many different forms, and should not be construed as being limited to the description of the embodiments exemplified below. Furthermore, to clarify the explanation, the drawings may schematically depict the width, thickness, shape, etc. of each part compared to the actual form, but these are merely examples and are not intended to limit the interpretation of the present disclosure. Furthermore, in this specification and each drawing, elements similar to those previously described with reference to the preceding drawings will be designated by the same reference numerals, and detailed descriptions may be omitted as appropriate.

[0019] In this specification, when describing a mode in which another component is placed on a certain component, the terms "above" or "below" are used, unless otherwise specified, to include both a case in which another component is placed directly above or below a certain component so as to be in contact with the component, and a case in which another component is placed above or below a certain component with another component interposed therebetween. Also, in this specification, when describing a mode in which another component is placed on the surface of a certain component, the terms "on the surface side" or "on the surface" are used, unless otherwise specified, to include both a case in which another component is placed directly above or below a certain component so as to be in contact with the component, and a case in which another component is placed above or below a certain component with another component interposed therebetween.

[0020] The proximity exposure photomask of the present disclosure will be described in detail below. Note that in this specification, the "proximity exposure photomask" may also be simply referred to as the "photomask."

[0021] A. Proximity exposure photomask FIG. 1(A) is a schematic plan view showing an example of a photomask according to the present disclosure, and FIG. 1(B) is a cross-sectional view taken along the line AA of FIG. 1(A). As shown in FIG. 1, the proximity exposure photomask 1 according to the present disclosure includes a transparent substrate 2 and a light-shielding film 3 disposed on the transparent substrate 2. The light-shielding film 3 includes a main light-shielding portion 31 having a substantially polygonal or circular opening O, and a light-shielding auxiliary pattern 32 disposed within the opening at a distance from the main light-shielding portion 31. The light-shielding film 3 is a phase shift film that shifts the phase of the exposure light used to expose the photomask by 180 degrees ±45 degrees, and has a transmittance of 1% or more and 10% or less for the exposure light. Furthermore, in the proximity exposure photomask 1 according to the present disclosure shown in FIG. 1, the region of the opening O is divided into an inner transparent region 42 and an outer transparent region 41 by the light-shielding auxiliary pattern 32.

[0022] According to the present disclosure, by using a phase shift film as a light-shielding film that shifts the phase of exposure light by 180 degrees ±45 degrees and forming a light-shielding auxiliary pattern inside the opening of the main light-shielding portion, the dimensions of the desired transfer pattern (e.g., a columnar pattern corresponding to the opening) can be made finer and the taper angle can be improved. This is presumably because, by using the phase shift film as a light-shielding film, light passing through the phase shift film and light passing through the transparent region of the opening interfere and weaken each other outside the boundary of the desired transfer pattern, and light passing through the transparent region separated by the light-shielding auxiliary pattern of the opening interfere and strengthen each other near the center of the desired transfer pattern, resulting in a steep light intensity distribution of the transmitted light. Therefore, the proximity exposure photomask of the present disclosure enables the dimensions of the transfer pattern to be made finer and the taper angle to be improved. Furthermore, since the dimensional fluctuation of the transfer pattern due to fluctuations in the exposure gap can be reduced, the transfer pattern can be formed with high accuracy even when the photomask is large. Furthermore, since the light intensity is high near the center of the desired transfer pattern, even if a high resolution unit (HRU) is used to reduce the exposure collimation angle, a decrease in production efficiency can be suppressed.

[0023] Figure 2(A) shows the light amplitude distribution at the image plane of a proximity exposure photomask (specifically, the surface of the photosensitive resin layer) when the light-shielding film is a 180-degree phase-shift film with a transmittance of 5.2%, and Figure 2(B) shows the light intensity distribution at the image plane of the photomask. As shown in Figure 2, the use of a phase-shift film causes interference between light L2 that has passed through the phase-shift film and light L1 that has passed through the transparent region of the opening outside the boundary of the desired transfer pattern (specifically, the position where the light intensity corresponds to the resolution threshold of the resist), weakening the light intensity outside the boundary.

[0024] When a photosensitive resin layer is patterned using the proximity exposure photomask of the present disclosure, a pattern corresponding to the auxiliary light-shielding pattern is not resolved, and only a pattern corresponding to the shape of the opening is formed.

[0025] As will be described later, the proximity exposure photomask of the present disclosure preferably has a light-shielding auxiliary pattern arranged so that the rising angle of the peak of the light intensity distribution of the transmitted light is larger than that of a reference photomask intended to form a transfer pattern of the same base size. Here, the reference photomask refers to a photomask having a light-shielding film that does not substantially transmit light and has openings formed on a transparent substrate that correspond to the transfer pattern, with no auxiliary pattern formed inside the openings.

[0026] The shape and position of such a light-shielding auxiliary pattern can be determined by simulating the light intensity distribution. The simulation of the light intensity distribution is based on the general Fresnel diffraction. The amplitude E of light at point P on the substrate is calculated by the following formula (1): P is calculated as the integral value of the spherical wave from each point of the corresponding opening (transparent area) of the proximity exposure photomask, and the light intensity I at point P can be calculated using the following equation (2).

[0027] 3 is a diagram for explaining the calculation of the light intensity distribution at point P on substrate 52 using the following formula (1), and is a schematic diagram showing the positional relationship between an arbitrary point Q in the opening of proximity exposure photomask 1 and an arbitrary point P on substrate 52. In FIG. 3, point S is the position on substrate 52 when exposure light 53 passes through point Q and travels straight ahead.

[0028]

number

[0029] Here, in equation (1), k=2π / λ, and E Pis the amplitude of light at point P on the substrate, A is a constant determined by the intensity of the incident light, λ is the wavelength of the incident light, δ is the angle between line segments QS and QP, r is the distance from point Q to point P, and i is the imaginary unit.

[0030] I=E P ×E P * (2) Here, in formula (2), E P * is E P The above calculation is performed by dividing the opening of the proximity exposure photomask into finite, minute sections and using a computer.

[0031] For example, in the case where there is one light-shielding auxiliary pattern placed inside the opening and the shape of the light-shielding auxiliary pattern is a continuous circular ring, if the diameter A of the opening, the width B of the light-shielding auxiliary pattern 32, and the inner diameter C of the light-shielding auxiliary pattern 32 shown in Figure 4 satisfy the following formula, the light intensity at the center of the transferred pattern can be reliably increased and the light intensity can be reduced outside the boundary of the transferred pattern (specifically, the position where the light intensity corresponds to the resolution threshold of the resist).

[0032] A×S1+S2-S3≦C≦A×S1+S2+S3 (3) (Wherein, 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))

[0033] Figure 5 shows the results of a simulation of the relationship between the bottom size and slope value of a transferred pattern (columnar pattern) when using a photomask according to the present disclosure that satisfies the above formula (3). The transfer conditions were as follows: collision half angle: 0.7 degrees; light source of the exposure device: a four-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, the relationship between the bottom size and slope value of the columnar pattern was also simulated for the reference photomask.

[0034] As shown in Figure 5, it can be seen that with the reference photomask, when the bottom size (µm) of the transfer pattern is small, especially when the bottom size of the transfer pattern is 10 µm or less, the slope value decreases significantly. 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 gradient of the tangent at the resist resolution threshold in the simulation results of the light intensity distribution.

[0035] Thus, when the photomask of the present disclosure is used, the slope value becomes high, i.e., the taper angle of the transferred pattern becomes close to vertical. The taper angle refers to the angle between the side surface of the tapered layer and the bottom surface of the layer.

[0036] Depending on the application of the transfer pattern, the proximity exposure photomask in the present disclosure does not necessarily need to have the shading auxiliary pattern arranged so that the rise angle of the peak of the light intensity distribution of the transmitted light is larger than that of a reference photomask intended for a transfer pattern of the same base size.

[0037] Each component of the photomask of the present disclosure will be described in detail below.

[0038] 1. Main light-shielding part The main light-shielding portion of the photomask in the present disclosure is disposed on a transparent substrate, and has substantially polygonal or substantially circular openings formed therein. The openings are regions corresponding to a desired transfer pattern (design pattern). The number of openings in the main light-shielding portion is not particularly limited, and may be one or more.

[0039] The shape of the opening is selected appropriately depending on the type and application of the proximity exposure photomask. In this disclosure, "approximately circular" refers to a circle (a perfect circle) or an ellipse whose maximum diameter is greater than 1 and not greater than 3.0 when the minimum diameter is 1. Furthermore, "approximately polygonal" refers to a regular polygon or a polygon whose longest straight line, drawn from each corner through the center, has a length of greater than 1 and not greater than 3.0 when the length of the shortest straight line is 1.

[0040] 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 about 10 μm or more and 15 μm or less. When the opening is substantially polygonal, the diameter of the opening refers to the length of a straight line drawn from each corner through the center. Furthermore, when the opening is an ellipse or a polygon other than a regular polygon, it is preferable that the minimum diameter is within the above range.

[0041] 2. Light blocking auxiliary pattern The auxiliary light-shielding patterns of the proximity exposure photomask of the present disclosure are formed inside the openings of the main light-shielding portions at a distance from the main light-shielding portions. It is preferable that such auxiliary light-shielding patterns have a width, size, and distance from the main light-shielding portions that increase the peak rise angle of the light intensity distribution of the transmitted light when a reference photomask for a transfer pattern of the same base size is exposed under the same conditions. The above-mentioned same conditions mean that the exposure wavelength, exposure gap, and exposure collimation angle are the same.

[0042] The number of auxiliary light-blocking patterns disposed inside the opening may be one or two or more.

[0043] A photomask for proximity exposure in which one auxiliary light-shielding pattern is arranged inside an opening will be described below. As shown in Fig. 1, the auxiliary light-shielding pattern 32 is preferably arranged so that the light intensity near the center of the transferred pattern increases due to interference between light that passes through an inner transparent region 42 inside the auxiliary light-shielding pattern 32 and light that passes through an outer transparent region 41, which is the gap between the auxiliary light-shielding pattern 32 and the main light-shielding portion 31, in the opening O.

[0044] A photomask for proximity exposure in which two light-shielding auxiliary patterns are arranged inside an opening will be described. The photomask for proximity exposure shown in Fig. 6 has a first light-shielding auxiliary pattern 32a and a second light-shielding auxiliary pattern 32b formed inside the opening O from the side of the main light-shielding portion 31. The second light-shielding auxiliary pattern and the first light-shielding auxiliary pattern are preferably arranged so that the light intensity near the center of the transferred pattern is increased due to interference between light passing through a transparent region 43 inside the second light-shielding auxiliary pattern 32b, a transparent region 42 that is the gap between the first light-shielding auxiliary pattern 32a and the second light-shielding auxiliary pattern 32b, and a transparent region 41 that is the gap between the first light-shielding auxiliary pattern 32a and the main light-shielding portion 31.

[0045] The specific size and width of the light-shielding auxiliary pattern and the distance between the main light-shielding portion and the light-shielding auxiliary pattern can be determined by simulating the light intensity distribution based on the Fresnel diffraction described above.

[0046] Specific shapes of the light-shielding auxiliary pattern include various shapes such as a circular ring shape and a polygonal ring shape. The outer shape of the light-shielding auxiliary pattern may be similar to the shape of the opening of the main light-shielding portion, but it does not have to be similar, and a similar shape is preferable. This is because the shape of the transfer pattern is stable. The shape of the opening of the light-shielding auxiliary pattern may be similar to the shape of the opening of the main light-shielding portion, but it does not have to be similar.

[0047] Furthermore, the center of the light-shielding auxiliary pattern and the center of the opening in the main light-shielding portion are preferably concentric. Here, "the center of the light-shielding auxiliary pattern being concentric with the center of the opening in the main light-shielding portion" means that the center of the light-shielding auxiliary pattern is within a circle with a radius of 1 μm from the center of the opening in the main light-shielding portion.

[0048] The light-shielding auxiliary pattern may be formed continuously or discontinuously.

[0049] When there is one light-shielding auxiliary pattern disposed inside the opening, its width ((B) in FIG. 4) is preferably 0.5 μm or more, more preferably 0.8 μm or more. On the other hand, it is preferably 8.0 μm or less, more preferably 7.0 μm or less. A specific range is preferably from 0.5 μm to 8 μm, and more preferably from 0.8 μm to 7.0 μm. If the width of the light-shielding auxiliary pattern is less than the above range, the desired effect of the light-shielding auxiliary pattern cannot be obtained. If the width exceeds the above range, there is a risk of it being resolved when exposure and development are performed using a proximity exposure photomask.

[0050] 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, it is preferably 19 μm or less, more preferably 11 μm or less. A specific range is preferably about 1 μm or more and 19 μm or less, and particularly preferably about 2 μm or more and 11 μm or less.

[0051] 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, it is preferably 4 μm or less, more preferably 2.0 μm or less. A specific range is preferably 1 μm or more and 4 μm or less, and particularly preferably 1.5 μm or more and 2.0 μm or less.

[0052] Furthermore, when there are two light-shielding auxiliary patterns (first and second light-shielding auxiliary patterns) arranged inside the opening, the width of the first and second light-shielding auxiliary patterns is preferably 0.8 μm or more. On the other hand, 3.0 μm or less is preferable, and 2.0 μm or less is particularly preferable. Specifically, the width range is preferably 0.8 μm or more and 3.0 μm or less, and particularly preferably 0.8 μm or more and 2.0 μm or less.

[0053] 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, it is preferably 4 μm or less, and more preferably 2.0 μm or less. A specific range is preferably 1 μm or more and 4 μm or less, and particularly preferably 1.0 μm or more and 2.0 μm or less.

[0054] 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, and 4.0 μm or less is preferable, with 2.0 μm or less being particularly preferable. A specific range is preferably 1.0 μm or more and 4.0 μm or less, and particularly preferably 1.0 μm or more and 2.0 μm or less.

[0055] Furthermore, it is preferable that the thickness of the light-shielding auxiliary pattern is approximately the same as the thickness of the main light-shielding portion, because, as described above, the light-shielding auxiliary pattern and the main light-shielding portion can be formed simultaneously in the manufacturing process of the proximity exposure photomask of the present invention.

[0056] 3. Light-shielding film The light-shielding film in the present disclosure includes the main light-shielding portion and the auxiliary light-shielding 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 has a transmittance of 1% or more, preferably 4% or more, for the exposure light. Meanwhile, the light-shielding film has a transmittance of 10% or less, preferably 7% or less. The 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, the exposure light may be any one of j-line (313 nm), i-line (365 nm), h-line (405 nm), and g-line (436 nm), or a mixed wavelength including these wavelength ranges.

[0057] By using a light-shielding film with such a phase shift effect, the transmitted light exhibits a steep light intensity distribution, as described above. The transmittance can be measured using the transmittance of the transparent substrate (described later) as a reference (100%). A UV-visible spectrophotometer (e.g., Hitachi U-4000) can be used to measure the average transmittance. The measurement conditions for the UV-visible spectrophotometer (Hitachi U-4000) are summarized in Table 1.

[0058] [Table 1]

[0059] 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 at which the transmittance is highest among the mixed wavelengths.

[0060] The light-shielding film may be configured as a single layer film by selecting a material that can achieve the above transmittance at a thickness that shifts the phase of the exposure light by 180°±45°. Alternatively, the light-shielding film may be configured as a two-layer film consisting of a phase adjustment layer made of a material with high transmittance that mainly shifts the phase by 180°±45°, and a transmittance adjustment layer made of a material with low transmittance that mainly determines the transmittance.

[0061] When constructing a light-shielding film as a single layer, a material is selected that has a high refractive index n (usually 1.5 or higher) and a thickness d that shifts the phase of exposure light of wavelength λ by 180°±45°, and that provides the desired transmittance in the range of 1% to 10%. Examples of materials for such a semi-transparent phase shift film constructed as a single layer include chromium oxynitride (CrON), molybdenum silicide nitride (MoSiN), molybdenum silicide oxynitride (MoSiON), silicon oxynitride (SiON), and titanium oxynitride (TiON), and the transmittance can be adjusted by changing the oxygen and nitrogen content.

[0062] The light-shielding film is required to have a film thickness that shifts the phase of the exposure light by 180 degrees ±45 degrees, and there is a relationship of Φ=2π(n-1)d / λ between the film thickness d of the main light-shielding portion, the refractive index n, the wavelength λ of the exposure light, and the phase difference Φ that occurs when the exposure light passes through the main light-shielding portion and the auxiliary light-shielding pattern, and since the phase difference is reversed when Φ=π, the film thickness d at which the phase difference is reversed is λ / 2(n-1). Note that 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.

[0063] When a light-shielding film is constructed with two layers, first, a material with a high refractive index and high light transmittance at the exposure wavelength is selected as the material for the phase adjustment layer to invert the phase, and then a material with low transmittance at the exposure wavelength is selected as the material for the transmittance adjustment layer, and the thickness of each is adjusted so that the phase of the exposure light is inverted as a whole and the transmittance becomes the desired value. Materials used for the phase adjustment layer include chromium oxide nitride (CrON), chromium oxide fluoride (CrFO), silicon oxide nitride (SiON), molybdenum oxynitride silicide (MoSiON), and titanium oxide nitride (TiON), and materials used for the transmittance adjustment layer include chromium (Cr), chromium nitride (CrN), tantalum (Ta), and titanium (Ti). Specific examples of material combinations for forming a two-layer semitransparent phase shift film include a phase adjustment layer made of chromium oxynitride (CrON) and a transmittance adjustment layer made of chromium nitride (CrN), a phase adjustment layer made of chromium fluoride (CrFO) and a transmittance adjustment layer made of chromium nitride (CrN), and a phase adjustment layer made of molybdenum oxynitride (MoSiON) and a transmittance adjustment layer made of molybdenum oxynitride (MoSiON) with a lower oxygen ratio than the phase adjustment layer.

[0064] In the present disclosure, a specific example is a single-layer chromium oxide nitride (CrON) film.

[0065] 4.Transparent substrate The transparent substrate used in the present invention is not particularly limited as long as it is capable of forming the main light-shielding portion and auxiliary light-shielding pattern, and a transparent substrate used in a general photomask can be used. Examples of the transparent substrate include optically polished low-expansion glass such as borosilicate glass and aluminoborosilicate glass, inflexible transparent rigid materials such as quartz glass, synthetic quartz glass, Pyrex (registered trademark) glass, soda-lime glass, and white sapphire, and flexible transparent flexible materials such as transparent resin films and optical resin films. Among these, 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.

[0066] 5. Proximity exposure photomask Next, the proximity exposure photomask of the present disclosure will be described. The proximity exposure photomask of the present disclosure is not particularly limited as long as it is a photomask having a light-shielding film including the main light-shielding portion and the auxiliary light-shielding pattern formed on the transparent substrate.

[0067] The proximity exposure photomask of the present disclosure typically has a main light-shielding portion in which one or more openings are formed, and one or more of the above-described light-shielding auxiliary patterns arranged inside the openings. The multiple openings formed in the main light-shielding portion of the proximity exposure photomask of the present disclosure may be the same as or different from each other in shape and size. Furthermore, the light-shielding auxiliary patterns arranged inside each opening may also be the same as or different from each other in shape, size, and position within the opening.

[0068] Furthermore, in the present disclosure, at least one of the multiple openings formed in the main shading portion of the proximity exposure photomask may have the above-mentioned shading auxiliary pattern arranged on the inside, and there may also be an opening that does not have a shading auxiliary pattern arranged on the inside.

[0069] In recent years, with the trend toward higher definition and thinner LCD panels and the addition of touch panel functions, there has been an increasing demand for spacers to be made smaller and more durable. For example, color filters have been developed that include a first photospacer and a second photospacer that is shorter (thinner) than the first photospacer.

[0070] By including a photomask for proximity exposure in the present disclosure that includes multiple combinations of openings and auxiliary light-shielding patterns, or by including openings with auxiliary light-shielding patterns as well as openings without auxiliary light-shielding patterns, it is possible to form columnar patterns (e.g., photospacers) of different heights (thicknesses) or different dimensions (diameters) with a single mask.

[0071] The proximity exposure photomask of the present invention is not particularly limited to a specific exposure light source, but the exposure light source may be, for example, a mercury lamp, and the exposure light may be any of j-line (313 nm), i-line (365 nm), h-line (405 nm), and g-line (436 nm), or a mixed wavelength including these wavelength ranges. When the above-mentioned mixed wavelength exposure light is used, it has the advantage that the exposure energy given to the photosensitive resin layer in the transparent region can be increased and the exposure time can be shortened.

[0072] The proximity exposure photomask of the present invention is also suitable for use in forming a fine columnar pattern corresponding to the openings using a negative resist. Specifically, it is particularly useful in forming photospacers for color filters for liquid crystal displays, as described below. However, the present invention is not limited to this case, and it can also be used in forming fine holes corresponding to the openings using a positive resist.

[0073] B. Color filter manufacturing method The method for manufacturing a color filter according to the present disclosure is a method for manufacturing a color filter having a black matrix, colored pixels, and photospacers on a transparent substrate for a color filter, and is characterized by including a photospacer formation step of forming photospacers including a columnar pattern corresponding to the openings in the main light-shielding portion using the above-described proximity exposure photomask.

[0074] (1) Photospacer formation process The photospacer forming 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, the step can be 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 the same pattern as the opening.

[0075] The photospacer-forming composition used in this process is preferably one that is not easily exposed to light in areas other than the transfer pattern (columnar pattern), and the resolution threshold of the resist is preferably equal to or greater than the intensity of light transmitted through the phase shift film.

[0076] The shape of the columnar pattern formed by this process is typically a cylindrical or 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 preferred, and 8 μm or more is preferred. A specific range is preferably 5 μm or more and 17 μm or less, and particularly preferably 8 μm or more and 12 μm or less.

[0077] The height of the columnar pattern formed by this process 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. The specific range is usually about 1.0 μm or more and 4.0 μm or less, preferably about 1.5 μm or more and 3.0 μm or less.

[0078] Furthermore, by using the proximity exposure photomask of the present disclosure, it is possible to manufacture a color filter including a first photospacer and a second photospacer that is lower than the first photospacer. In this case, the transfer pattern corresponding to the opening of the proximity exposure photomask of the present disclosure may be at least one of the first photospacer and the second photospacer.

[0079] Specifically, in this process, a negative resist composition for forming photospacers is applied to a transparent substrate for a color filter on which a black matrix and colored pixels have been formed, dried, exposed to light through a mask to harden the exposed areas, and developed using an alkaline developer, thereby enabling patterning of the photospacers.

[0080] The photospacers are preferably formed above the non-display area, ie, the black matrix.

[0081] (2) Other processes The method for producing a color filter of this embodiment includes the photospacer formation step. There are no particular limitations on the method as long as it is a method that can be used, and the method may include necessary steps such as a black matrix forming step of forming a black matrix, a colored layer forming step of forming a colored layer, a transparent electrode layer forming step of forming a transparent electrode layer on the colored layer, etc. Each of these steps can be the same as each step in a general color filter manufacturing method.

[0082] The present disclosure is not limited to the above-described embodiments. The above-described embodiments are merely examples, and any configuration that is substantially identical to the technical idea described in the claims of the present disclosure and that provides similar effects is included within the technical scope of the present disclosure. [Example]

[0083] The present disclosure will be described in more detail below with reference to examples and comparative examples.

[0084] (Comparative Example 1, Example 1) The difference in bottom dimension size at the same light intensity was determined by simulation for the photomasks of Comparative Example 1 and Example 1 set as follows. The photomask of Comparative Example 1 was a binary mask shown in FIG. 7(A) having a light-shielding film with an OD value of greater than 3 and openings with a diameter of 13 μm formed on a transparent substrate made of quartz glass. The photomask of Example 1 was a photomask shown in Figure 7(B), which had a transparent substrate made of quartz glass, a main light-shielding portion 31 made of a 180-degree phase shift film with a transmittance of 5.2% and an opening with a diameter of 14 μm, and a ring-shaped auxiliary light-shielding pattern 32 with a width of 2 μm and an inner diameter of 2 μm arranged inside the opening.

[0085] The light intensity distribution formed on the exposed object when proximity exposure was performed on the exposed object with an exposure gap G of 200 μm, so that the maximum light intensity was approximately the same as in Comparative Example 1 (1.87) and Example 1 (1.83), was obtained by simulation. The results are shown in Figure 7(C). Note that the maximum light intensity is the value when the incident light intensity is set to 1. Other transfer conditions were a collision half angle of 0.7 degrees, and exposure wavelength: a mixed wavelength of light containing j-line (313 nm), i-line (365 nm), h-line (405 nm), and g-line (436 nm).

[0086] From Fig. 7(C), it was calculated that the bottom size (Y in Fig. 7) of the transfer pattern obtained in Comparative Example 1 was 12.61 µm, and the bottom size (X in Fig. 7) of the transfer pattern obtained in Example 1 was 9.86 µm (Fig. 10(A)). In addition, the slope value was 0.093 for Comparative Example 1 and 0.170 for Example 1, and it was confirmed that the dimensions of the transfer pattern were smaller in Example 1 and the taper angle was also improved.

[0087] (Comparative Example 2, Example 2) The difference in taper angle when the lower base dimension size is the same was obtained by simulation for the photomasks of Comparative Example 2 and Example 2 set as follows. The photomask of Comparative Example 2 was a binary mask shown in FIG. 8(A) having a light-shielding film (OD value: greater than 3) with openings of 8 μm diameter formed on a transparent substrate made of quartz glass. The photomask of Example 2 was a photomask shown in Figure 8(B), which had a main light-shielding portion 31 with a transmittance of 5.2% and an opening with a diameter of 14 μm formed thereon, made of a 180-degree phase shift film, a ring-shaped light-shielding auxiliary pattern 32a with a width of 1 μm and an inner diameter of 8 μm, and a ring-shaped light-shielding auxiliary pattern 32b with a width of 1 μm and an inner diameter of 2 μm, arranged inside the opening.

[0088] The light intensity distribution formed on the exposed object was simulated when proximity exposure was performed on the exposed object with an exposure gap G of 200 μm, so that the bottom size of the resulting transferred pattern was approximately the same as Comparative Example 2 (9.38 μm) and Example 2 (9.28 μm). The results are shown in Figure 8(C). The transfer conditions were a collision half angle of 0.7 degrees and exposure wavelength of a mixed wavelength of j-line (313 nm), i-line (365 nm), h-line (405 nm), and g-line (436 nm).

[0089] 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. In addition, 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)).

[0090] Example 3 The photomask of Example 3 shown in FIG. 9(B) was a photomask having a 5.2% transmittance and a 180-degree phase shift film on a transparent substrate made of quartz glass, a main light-shielding portion 31 with a 17 μm diameter opening formed therein, and a ring-shaped auxiliary light-shielding pattern 32 with a width of 1 μm and an inner diameter of 13 μm arranged inside the opening. The light intensity distribution when proximity exposure was performed so that the exposure gap G was 200 μm and the transferred pattern size was 13.2 μm was obtained by simulation. The maximum light intensity in Example 3 was 2.011. The transfer conditions were a collision half angle of 0.7 degrees and exposure wavelength of a mixed wavelength of j-line (313 nm), i-line (365 nm), h-line (405 nm), and g-line (436 nm). The exposure gap was changed to 180 μm, and the transferred pattern size when proximity exposure was performed under the above transfer conditions was also obtained by simulation. The rate of change in the transferred pattern dimension CD (ΔCD / ΔGap) due to the change in the exposure gap from 200 μm to 180 μm was calculated using the following formula and was found to be 0.003. ΔCD / ΔGap=(CD 200 -CD 180 ) / (200μm-180μm) In the formula, CD 200is the transfer pattern dimension when the exposure gap is 200 μm, and CD 180 is the transferred pattern dimension when the exposure gap is 180 μm.

[0091] (Comparative Example 3) The photomask of Comparative Example 3 was a binary mask shown in FIG. 9(A), which had a transparent substrate made of quartz glass and a light-shielding film with an OD value greater than 3 and an aperture of 14 μm in diameter. The photomask of Comparative Example 3 was subjected to proximity exposure under the same transfer conditions as in Example 3, with an exposure gap G of 200 μm and a bottom size of the transferred pattern of 13.3 μm, approximately the same as in Example 3. The light intensity distribution was calculated 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. The light intensity distribution obtained by simulation when only the exposure gap was changed to 180 μm is also shown in FIG. 9(C). The rate of change in the transferred pattern dimension CD (ΔCD / ΔGap) due to the change in the exposure gap from 200 μm to 180 μm was calculated using the above formula. ΔCD / ΔGap was 0.027. It was confirmed that the variation in the transferred pattern dimension due to the variation in the exposure gap was smaller in Example 3 than in Comparative Example 3 (FIG. 10(C)).

[0092] Example 4 The light intensity distribution formed on the exposed object was simulated using a proximity exposure photomask with two types of opening patterns, one for the first photospacer and one for the second photospacer, as shown in Figures 11(A) and 11(B). The results are shown in Figure 11(C). The light-shielding film 3 was a 180-degree phase-shift film with a transmittance of 5.2%. The transfer conditions were a collision half angle of 0.7 degrees, exposure wavelengths of a mixed wavelength of j-line (313 nm), i-line (365 nm), h-line (405 nm), and g-line (436 nm), and an exposure gap of 200 μm. The opening patterns in Figure 11(A) and Figure 11(B) have the same bottom dimension of 11.8 μm, but 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 using a single mask. [Explanation of symbols]

[0093] 1. Proximity exposure photomask 2...Transparent substrate 3... Light-shielding film 31... Main shading part 32... Light blocking auxiliary pattern

Claims

1. A photomask for proximity exposure, comprising: A transparent substrate and a light-shielding film disposed on the transparent substrate, the light-shielding film has a main light-shielding portion in which a substantially polygonal or substantially circular opening is formed, and a light-shielding auxiliary pattern that is disposed inside the opening of the main light-shielding portion and is formed at a distance from the main light-shielding portion, The light-shielding film has a phase shift effect of shifting the phase of exposure light by 180 degrees ±45 degrees, and is a phase shift film having a transmittance of the exposure light of 1% or more and 10% or less.

2. The proximity exposure photomask of claim 1, wherein the light-shielding auxiliary pattern is arranged so that the rise angle of the peak of the light intensity distribution of the passed light is larger than that of a reference photomask intended to form a transfer pattern of the same bottom size.

3. 3. The proximity exposure photomask according to claim 1, wherein the diameter of the opening is 10 [mu]m or more and 20 [mu]m or less.

4. 4. The proximity exposure photomask according to claim 1, wherein the exposure light is light with a mixed wavelength of j-line (313 nm), i-line (365 nm), h-line (405 nm), and g-line (436 nm).

5. A method for manufacturing a color filter including a black matrix, colored pixels, and photospacers on a transparent substrate for a color filter, the method comprising:

5. A method for manufacturing a color filter, comprising: a photospacer formation step of forming photospacers including a columnar pattern corresponding to the openings in the main light-shielding portion, using a proximity exposure photomask according to any one of claims 1 to 4.

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