Photomask for manufacturing display device, and method for manufacturing display device

Abstract

This invention provides a photomask for manufacturing a display device, which can stably form a fine aperture pattern on a transfer substrate. The photomask is configured to have a transfer pattern on a transparent substrate. The transfer pattern includes: a main pattern consisting of quadrilateral light-transmitting portions; an auxiliary pattern consisting of phase-shifting portions disposed around the periphery of the main pattern; and low-light-transmitting portions formed outside the main pattern and the auxiliary pattern. When a regular octagonal band of a predetermined width surrounding the main pattern is defined around the periphery of the main pattern, the auxiliary pattern constitutes at least a portion of the regular octagonal band. One of the multiple main patterns included in the transfer pattern is designated as a first main pattern, and a second main pattern, different from the first main pattern, is disposed close to the first main pattern. An auxiliary pattern with a missing section in at least one of the eight blocks constituting the regular octagonal band surrounding the first main pattern is disposed around the periphery of the first main pattern.

Description

[0001] This application is a divisional application of the parent application filed by HOYA Co., Ltd., entitled "Photomask for Manufacturing a Display Device and Method for Manufacturing a Display Device", filed on March 7, 2018, with application number 201810185361.6. Technical Field

[0002] This invention relates to photomasks for manufacturing electronic devices, particularly suitable photomasks for use in manufacturing display devices (flat panel displays: FPDs). Background Technology

[0003] Patent document 1 describes a photomask that provides an exposure environment suitable for manufacturing molds for display devices and is capable of stably transferring fine patterns.

[0004] In addition, Patent Document 2 describes a photomask for forming fine patterns used in the manufacture of semiconductor integrated circuit devices, and a method for simultaneously miniaturizing isolated patterns and dense patterns.

[0005] Patent Document 1: Japanese Patent Application Publication No. 2016-024264

[0006] Patent Document 2: Japanese Patent Application Publication No. 2006-338057

[0007] In display devices, including liquid crystal displays and organic EL (organic electroluminescence) displays, there is a desire for brighter and more energy-efficient displays, as well as improved display performance such as high definition, high speed, and wide viewing angle.

[0008] For example, in the case of the thin-film transistor (TFT) used in the aforementioned display device, if the contact holes formed in the interlayer insulating film among the multiple patterns constituting the TFT do not reliably connect the patterns of the upper and lower layers, accurate operation cannot be guaranteed. On the other hand, for example, in order to form a display device that maximizes the aperture ratio of the liquid crystal display device to increase brightness and save power, it is desirable to reduce the diameter of the hole pattern (e.g., less than 3 μm) as the display device requires high density, such as sufficiently small contact hole diameters. For example, it is necessary to have hole patterns with a diameter of 0.8 μm or more and 2.5 μm or less, and further, a diameter of 2.0 μm or less. Specifically, it is also desirable to form patterns with a diameter of 0.8 μm to 1.8 μm.

[0009] However, compared to display devices, in the field of photomasks for semiconductor device (LSI) manufacturing, where integration is high and pattern miniaturization has significantly advanced, there has been a trend towards shorter wavelengths of exposure light in order to achieve higher resolution using optical systems with high numerical apertures (NA), such as those exceeding 0.2. As a result, in this field, KrF and ArF excimer lasers (single wavelengths of 248 nm and 193 nm, respectively) are mostly used.

[0010] On the other hand, in the field of photolithography for display device manufacturing, methods like those described above are generally not used to improve resolution. For example, the NA (numerical aperture) of the optical systems in exposure apparatus used in this field is around 0.08 to 0.12, and even looking to the future, it will be below 0.20, for example, in environments where it is around 0.08 to 0.15. In addition, the light sources used for exposure mostly use i-lines, h-lines, or g-lines, and mainly use wide-wavelength light sources that include these, thus obtaining the amount of light needed to illuminate a large area, and there is a strong trend towards prioritizing production efficiency and cost.

[0011] Furthermore, as mentioned above, the demand for pattern miniaturization is increasing in the manufacturing of display devices. Here, several problems arise from simply applying semiconductor device manufacturing technologies to display device manufacturing. For example, the conversion to high-resolution exposure equipment with high numerical aperture (NA) requires significant equipment investment, making it unsuitable for the price of display devices. Additionally, changes in exposure wavelength (using short wavelengths like ArF excimer lasers) are undesirable for large-area display devices, not only reducing production efficiency but also requiring substantial equipment investment. In other words, while pursuing unprecedented pattern miniaturization, existing advantages such as cost and efficiency cannot be sacrificed; this becomes a key issue for photomasks used in display device manufacturing.

[0012] The inventors of this invention propose a photomask comprising: a main pattern consisting of a light-transmitting portion; an auxiliary pattern disposed near the main pattern and consisting of a phase-shifting portion that phase-shifts light of a predetermined wavelength; and a low-transmittance portion formed in an area other than the main pattern and the auxiliary pattern (Patent Document 1). This photomask can be effectively used when stably forming fine, isolated holes on a transfer substrate such as a display panel substrate.

[0013] On the other hand, the inventors of this invention have discovered a new problem: as the structure of display devices becomes more complex, the design of transfer patterns also becomes more complex, and even using the photomask described in Patent Document 1 cannot completely eliminate this problem. For example, when multiple hole patterns are arranged at a predetermined close distance on the substrate to form a dense pattern, the auxiliary patterns of each main pattern in the transfer pattern on the photomask are close to each other. In this case, the transmitted light from the auxiliary patterns, which are not intended for transfer, loses resist thickness on the substrate, creating a risk of hindering the formation of the intended transfer image. Here, a dense pattern refers to a pattern in which two or more hole patterns are arranged close to each other on the substrate, and therefore refers to a pattern in which two or more main patterns are arranged close to each other on the photomask. A closely arranged pattern refers to a pattern on the photomask where the hole-forming patterns are at a distance that has an optical influence on each other under the exposure environment. In this application specification, in addition to the case where the main patterns are close to each other, there are sometimes patterns referred to as closely arranged patterns, including auxiliary patterns accompanying the main patterns.

[0014] Patent Document 2 describes a photomask used for manufacturing semiconductor integrated circuit devices by exposure using a reduction projection exposure system with ring illumination. Specifically, it describes a method where, in a pattern having contour phase shifters surrounding an opening, the phase shifters corresponding to adjacent patterns are combined to form a single phase shifter when the spacing between them decreases. Figure 15 As shown, when four contour phase shifters 711, 712, and 713 surround the opening patterns 721, 722, and 723 respectively, when the interval between the opening patterns 722 and 723 is small, the contour phase shifter 714 becomes a contour phase shifter shared by both the opening patterns 722 and 723. Furthermore, the photomask described in Patent Document 2 is useful for simultaneously miniaturizing isolated blank patterns and isolated line patterns or dense patterns.

[0015] However, according to the inventors' research based on the present invention, it has been found that using the method described in Patent Document 2 in the photomask for manufacturing a display device may not be useful. Summary of the Invention

[0016] Therefore, the object of the present invention is to provide a photomask for manufacturing a display device that can stably form a fine hole pattern on a transfer substrate when manufacturing a display device.

[0017] (First method)

[0018] The first aspect of the present invention is a photomask for manufacturing a display device, which has a transfer pattern on a transparent substrate, characterized in that...

[0019] The above-mentioned transfer patterns include:

[0020] The main pattern is composed of translucent quadrilateral sections;

[0021] An auxiliary pattern, which is composed of phase-shifted portions arranged around the periphery of the main pattern; and

[0022] The low-transmittance portion is formed in an area other than the main pattern and the auxiliary pattern described above.

[0023] When a regular octagonal band of a specified width is defined around the main pattern, the auxiliary pattern constitutes at least a portion of the regular octagonal band.

[0024] When one of the multiple main patterns included in the above-mentioned transfer pattern is designated as the first main pattern, a second main pattern different from the first main pattern is positioned close to the first main pattern.

[0025] In one of the eight blocks that constitute the regular octagonal band surrounding the first main pattern, an auxiliary pattern is missing in one block facing the second main pattern and is arranged around the first main pattern.

[0026] (Second method)

[0027] The second aspect of the present invention is the photomask for manufacturing a display device described in the first aspect above, characterized in that,

[0028] When the diameter of the main pattern is set to W1, the transfer pattern forms a hole pattern with a diameter of W2 on the object to be transferred as the transfer image of the main pattern, where W1≥W2.

[0029] (Third method)

[0030] The third aspect of the present invention is a photomask for manufacturing a display device as described in the first or second aspect above, characterized in that,

[0031] When the arrangement direction of the first main pattern and the second main pattern is set to the X direction, the size of the first main pattern in the X direction is smaller than the size of the first main pattern in the Y direction, which is perpendicular to the X direction.

[0032] (Fourth method)

[0033] The fourth aspect of the present invention is a photomask for manufacturing a display device as described in any one of the first to third aspects above, characterized in that,

[0034] The aforementioned transfer pattern includes three or more of the aforementioned main patterns arranged in a dense pattern in the X direction, in the Y direction perpendicular to the aforementioned X direction, or in both the X direction and the aforementioned Y direction. The aforementioned transfer pattern, for each of the main patterns constituting the aforementioned dense pattern, has an auxiliary pattern that causes at least one of the aforementioned eight blocks to be missing on the side facing other main patterns.

[0035] (Fifth method)

[0036] The fifth aspect of the present invention is a photomask for manufacturing a display device as described in any one of the first to fourth aspects above, characterized in that,

[0037] The phase-shifting portion is formed by forming a phase-shifting film on the transparent substrate. The transmittance of the phase-shifting film relative to the representative wavelength of the exposure light is 20% to 80%, and the phase-shifting film shifts the phase of the exposure light by approximately 180 degrees.

[0038] (Sixth method)

[0039] The sixth aspect of the present invention is a photomask for manufacturing a display device as described in any one of the first to fifth aspects above, characterized in that,

[0040] The aforementioned low-transmittance section is a light-shielding section with an optical density (OD) of 2 or higher relative to the light used for exposure.

[0041] (Seventh Method)

[0042] The seventh aspect of the present invention is a method for manufacturing a display device, characterized in that it includes:

[0043] The process of preparing the photomask described in any of the first to sixth methods above; and

[0044] The process of exposing the above-mentioned transfer pattern to an exposure apparatus having an exposure light source including at least one of i-line, h-line and g-line, using a numerical aperture (NA) of 0.08 to 0.15, to form a hole pattern with a diameter W2 of 0.8 μm to 3.0 μm on the transfer substrate.

[0045] According to the present invention, it is possible to stably form a fine hole pattern on a transfer substrate during the manufacture of a display device. Attached Figure Description

[0046] Figure 1 This is a diagram showing the main part of the pattern for transferring the photomask described in Patent Document 1. Figure 1 (a) is a top view diagram. Figure 1 (b) is Figure 1 (a) Schematic cross-sectional view of position AA.

[0047] Figure 2 (a) to (c) are top views showing the patterns of the photomasks in Reference Examples 1 to 3.

[0048] Figure 3 This is a graph showing the simulation results of reference examples 1 to 3.

[0049] Figure 4 This is a top view showing the arrangement of the main patterns in Reference Example 3 close to each other.

[0050] Figure 5 (a) is a top view illustrating the case where the first and second main patterns are fully separated. Figure 5 (b) is a cross-sectional view illustrating the structure of the resist pattern formed on the transfer substrate in this case.

[0051] Figure 6 (a) is a top view illustrating the case where the second main pattern is close to the first main pattern. Figure 6 (b) is a cross-sectional view illustrating the structure of the resist pattern formed on the transfer substrate in this case.

[0052] Figure 7 The diagram illustrates the main parts of the transfer pattern of a photomask for manufacturing a display device according to an embodiment of the present invention. Figure 7 (a) is a top view diagram. Figure 7 (b) is Figure 7 (a) is a cross-sectional view of the BB position.

[0053] Figure 8 This is a top view showing an example of dividing the auxiliary patterns arranged around the main pattern into eight blocks.

[0054] Figure 9 This is a cross-sectional view illustrating the structure of an resist pattern formed on a transfer body when a transfer pattern of a photomask according to an embodiment of the present invention is applied.

[0055] Figure 10 (a) to (e) are top views showing the patterns of the photomasks in Reference Examples 4 to 8.

[0056] Figure 11 (f) to (i) are top views showing the patterns of the photomasks in Examples 1 to 4.

[0057] Figure 12 These are diagrams illustrating simulation results of reference examples and embodiments in the implementation of the present invention.

[0058] Figure 13This is a top view showing an example of a transfer pattern for a photomask, including a master pattern with a mask bias β2.

[0059] Figure 14 (a) to (f) are process diagrams illustrating an example of a method for manufacturing a photomask that can be applied to embodiments of the present invention.

[0060] Figure 15 This is a top view showing the pattern of the photomask described in Patent Document 2.

[0061] Explanation of reference numerals in the attached figures:

[0062] 1 (1a, 1b)…Main pattern; 2 (2a, 2b)…Auxiliary pattern; 3…Low transmittance section; 4…Transmittance section; 5…Phase shift section; 10…Transparent substrate; 11…Phase shift film; 12…Low transmittance film. Detailed Implementation

[0063] [Design of photomasks for forming aperture patterns with auxiliary patterns]

[0064] Figure 1 This shows the main part of the transfer pattern of the photomask described in Patent Document 1. Figure 1 (a) is a top view diagram. Figure 1 (b) is Figure 1 (a) Schematic cross-sectional view of position AA.

[0065] The photomask shown in the figure has a main pattern 1 composed of light-transmitting parts and an auxiliary pattern 2 arranged around the main pattern 1. The auxiliary pattern 2 is attached to the main pattern 1 and arranged around the main pattern 1.

[0066] Furthermore, a phase-shifting film 11 and a low-transmittance film 12 are formed on the transparent substrate 10. The main pattern 1 is formed by the light-transmitting portion 4 exposed on the transparent substrate 10, and the auxiliary pattern 2 is formed by the phase-shifting portion 5 exposed on the phase-shifting film 11 on the transparent substrate 10. In addition, the low-transmittance portion 3 surrounds the main pattern 1 and the auxiliary pattern 2 respectively.

[0067] The low-transmittance portion 3 is composed of a laminated film of a phase-shifting film 11 and a low-transmittance film 12 formed on the transparent substrate 10. Alternatively, the low-transmittance portion 3 can be composed of a single layer of the low-transmittance film 12 formed on the transparent substrate 10. In other words, the low-transmittance portion 3 is composed of a portion having at least the low-transmittance film 12 formed on it. In the illustrated transfer pattern, the area outside the range where the main pattern 1 and the auxiliary pattern 2 are formed is defined as the low-transmittance portion 3.

[0068] The phase shift film 11 has a phase shift of approximately 180 degrees, shifting the exposure light of a representative wavelength within the wavelength range of the i-line to the g-line. That is, the auxiliary pattern 2 has the function of reversing the phase of the transmitted light using the phase shift film 11. Furthermore, the phase shift film 11 has a transmittance of T1 (%) relative to the aforementioned representative wavelength of the exposure light.

[0069] According to Patent Document 1, optical simulation of forming a hole pattern on a substrate using a photomask with the above-mentioned transfer pattern results in superior performance in Eop (the amount of light required to form a pattern of the target size on the substrate) and DOF (Depth of Focus) compared to binary masks and phase-shift masks without auxiliary patterns.

[0070] In order to further form fine patterns on the transfer substrate, the inventors of this invention targeted... Figure 2 Optical simulations are performed using the photomasks shown in (a) to (c). Here, Figure 2 The photomask of (a) is set as reference example 1, and the photomask of (a) is set as reference example 1. Figure 2 The photomask shown in (b) is set as reference example 2, and the photomask shown in (b) is set as reference example 2. Figure 2 The photomask shown in (c) is used as reference example 3. Then, using each of the photomasks of reference examples 1 to 3, which have a main pattern consisting of a hole pattern with a diameter W1 of 2.0 μm, a simulation of forming a transfer image with a hole pattern of a diameter W2 (here, 1.5 μm) is performed on the transfer substrate (display panel substrate, etc.) using a positive type photoresist.

[0071] Furthermore, as described above, the diameter W1 on the photomask is set to W1 ≥ W2 (preferably W1 > W2) relative to the target diameter W2 on the object to be transferred. Here, if the mask bias β1 (μm) is set to β1 = W1 - W2, then β1 is set to 0.5 (μm).

[0072] The simulation conditions are as follows.

[0073] (Refer to Example 1)

[0074] In reference example 1, such as Figure 2 As shown in (a), a photomask composed of a binary mask is used, and the aperture pattern composed of a square light-transmitting part with a diameter W1 = 2 μm, which surrounds the low light-transmitting part (light-shielding part) 3, is set as the main pattern 1.

[0075] (See Example 2 for reference)

[0076] In reference example 2, such as Figure 2As shown in (b), a photomask composed of a halftone phase-shift mask is used, and a hole pattern consisting of a square light-transmitting part with a diameter W1 = 2 μm is set as the main pattern 1, which is surrounded by a phase-shifting part 5 with a transmittance of 5.2% and a phase shift of 180 degrees for the light to be exposed.

[0077] (Refer to Example 3)

[0078] In reference example 3, such as Figure 2 As shown in (c), a photomask composed of a phase-shifting mask with an auxiliary pattern is used. The main pattern 1 is a hole pattern consisting of a square transparent portion with a diameter W1 = 2 μm, and the auxiliary pattern 2, forming a regular octagonal band, surrounds its periphery. Furthermore, the auxiliary pattern 2 is composed of a phase-shifting portion with a light transmittance of 45% and a phase shift of 180 degrees. The area outside the main pattern 1 and the auxiliary pattern 2 is composed of a low-transmittance portion (shielding portion) 3 with an optical density of OD ≥ 2. The distance (L) between the center of the main pattern 1 and the center of the auxiliary pattern 2 in the width direction is set to 3.25 μm, and the width (d) of the auxiliary pattern 2 is set to 1.3 μm. The photomask of Reference Example 3 is designed based on the structure described in Patent Document 1.

[0079] Using the photomasks corresponding to the above-mentioned Reference Examples 1 to 3, a hole pattern with a width W2 = 1.5 μm is formed on the transfer substrate.

[0080] The simulated exposure conditions are as follows.

[0081] The numerical aperture (NA) of the optical system of the exposure apparatus is 0.1, and the coherence factor (σ) is 0.5. Furthermore, for the light source used for exposure, a wide-wavelength light source including the i-line, h-line, and g-line is used, with an intensity ratio of g:h:i = 1:1:1.

[0082] The optical evaluation items for photomasks are as follows.

[0083] (1) Depth of Focus (DOF)

[0084] In cases of defocusing during exposure, the CD variation relative to the target CD on the transfer substrate is used to achieve a depth of focus within a specified range (e.g., ±10%), and a larger DOF value is desirable. A higher DOF value makes the substrate less susceptible to flatness issues (e.g., a panel substrate for a display device), enabling the reliable formation of fine patterns and suppressing CD deviation. In the simulation of this application, the DOF value is based on ±10% of the target CD. Here, CD is an abbreviation for Critical Dimension, used to indicate pattern width. Photomasks used in display device manufacturing are larger than those used in semiconductor device manufacturing, and the transfer substrate (such as a display panel substrate) is also larger. In either case, achieving perfect flatness is difficult, thus increasing the DOF value of the photomask is of great significance.

[0085] (2) Mask Error Enhancement Factor (MEEF)

[0086] MEEF is a numerical value representing the ratio of the CD error of the pattern formed on the substrate to the CD error of the photomask. The lower the MEEF, the more the CD error of the pattern formed on the substrate can be reduced. As display device specifications evolve, the requirements for pattern miniaturization are increasing, and photomasks with patterns approaching the resolution limits of exposure devices are needed. Therefore, MEEF is likely to be given more importance in the future of photomasks used in display device manufacturing.

[0087] (3) Eop

[0088] In photomasks used in display device manufacturing, Eop (hereinafter also referred to as "Eop Dose") is a crucial evaluation parameter. Eop is the amount of light required to form the desired pattern size on the substrate. The photomasks used in display device manufacturing are very large (e.g., squares or rectangles with one side of the main surface approximately 300–2000 mm). Therefore, using a photomask with a lower Eop value can increase the scanning exposure speed, thereby improving production efficiency.

[0089] exist Figure 3 The specific evaluation results for the above evaluation items are shown.

[0090] First, considering Eop (Exposure Optical Output), the photomask of Reference Example 3 reduces the exposure (Eop value) for obtaining the aperture pattern of the target size by more than 30% compared to the photomasks of Reference Examples 1 and 2. Therefore, it can be seen that using the photomask of Reference Example 3 results in higher production efficiency. Furthermore, compared to the photomasks of Reference Examples 1 and 2, the photomask of Reference Example 3 has a higher DOF (Domain of Optical Output) and a lower MEEF (Mean Effect of Optical Output). Therefore, it can be seen that the photomask of Reference Example 3 is also very advantageous in terms of DOF and MEEF.

[0091] [Design of hole patterns located close to each other]

[0092] On the other hand, if the required resolution of the display device increases, the integration density increases by increasing the number of pixels per unit area. Therefore, as a transfer pattern for a photomask used in the manufacture of a display device, there is a need to arrange multiple main patterns (hole patterns) close to each other. Hereinafter, the case of applying the photomask of Reference Example 3 described above to the formation of a dense pattern including multiple main patterns will be studied.

[0093] Figure 4 This illustrates a case where the patterns used in Reference Example 3 (combining a main pattern and auxiliary patterns formed around it, also referred to in this application as hole-forming patterns) are arranged close to each other. Here, one of the two main patterns is designated as the first main pattern 1a, and the other as the second main pattern 1b. Then, as the position of the second main pattern 1b is moved closer to the first main pattern 1a in the direction of the arrow, the distance between the centroids of the two main patterns 1a and 1b, i.e., the hole spacing P, and the cross-sectional shape of the resist pattern formed on the transfer substrate are examined.

[0094] First, such as Figure 5 As shown in (a), when the first main pattern 1a and the second main pattern 1b are fully separated (P = 12 μm), as Figure 5 As shown in (b), the resist pattern (here, the pattern is composed of positive photoresist) 20 on the transfer body is formed with hole patterns 21a and 21b corresponding to the main patterns 1a and 1b, respectively.

[0095] On the other hand, such as Figure 6 As shown in (a), when the second main pattern 1b is close to the first main pattern 1a (P = 8 μm), the auxiliary patterns 2a and 2b arranged around each main pattern 1a and 1b become extremely close to each other. At this time, if the cross-section of the resist pattern 20 formed on the transfer substrate is observed, it appears as follows... Figure 6As shown in (b), in addition to the hole patterns 21a and 21b corresponding to the main patterns 1a and 1b, recesses 22 are formed in their middle portions, resulting in a significant loss of resist film thickness. There is a concern that such localized reduction of resist film may negatively impact the processing stability of display device substrates that are processed using the resist patterns as etching masks.

[0096] Therefore, the inventors of the present invention studied a photomask capable of eliminating this defect, based on the hole-forming pattern of Reference Example 3, which has advantageous characteristics in Eop and DOF and produces a localized reduction of such defective anti-corrosion residue as described above.

[0097] <Structure of Photomasks>

[0098] Next, the structure of the photomask for manufacturing a display device according to the embodiments of the present invention will be described.

[0099] The photomask for manufacturing a display device according to the embodiments of the present invention is a photomask for manufacturing a display device having a transfer pattern on a transparent substrate.

[0100] The above-mentioned transfer patterns include:

[0101] The main pattern is composed of translucent quadrilateral sections;

[0102] An auxiliary pattern composed of phase-shifted portions arranged around the periphery of the main pattern; and

[0103] Low-transmittance areas formed outside the aforementioned main pattern and auxiliary pattern,

[0104] When a regular octagonal band of a specified width is defined around the main pattern, the auxiliary pattern constitutes at least a portion of the regular octagonal band.

[0105] When one of the multiple main patterns included in the above-mentioned transfer pattern is designated as the first main pattern, a second main pattern different from the first main pattern is positioned close to the first main pattern.

[0106] In one of the eight blocks that constitute the regular octagonal band surrounding the first main pattern, an auxiliary pattern is missing in one block facing the second main pattern and is arranged around the first main pattern.

[0107] The following uses Figure 7 To explain in detail.

[0108] Figure 7 This diagram illustrates the main portions of a transfer pattern included in a photomask for manufacturing a display device according to an embodiment of the present invention. Figure 7 (a) is a top view diagram. Figure 7 (b) is Figure 7 (a) is a cross-sectional view of the BB position.

[0109] The photomask used for manufacturing the aforementioned display device (hereinafter referred to simply as a "photomask") includes, for example, a transfer pattern formed by patterning a phase-shifting film 11 and a low-transmittance film 12 deposited on a transparent substrate 10. The transfer pattern includes a main pattern 1 (1a, 1b) and auxiliary patterns 2 (2a, 2b) disposed around the periphery of the main pattern 1. When a regular octagonal band of a predetermined width is defined surrounding the main pattern 1, the auxiliary patterns 2 have at least a partial shape constituting the regular octagonal band.

[0110] There are two main patterns 1 arranged in the X direction, one of which is called the first main pattern 1a, and the other is called the second main pattern 1b. Auxiliary patterns 2a are arranged around the first main pattern 1a, and auxiliary patterns 2b are arranged around the second main pattern 1b. Furthermore, in... Figure 7 In (a), although the main pattern on the left is set as the first main pattern and the main pattern on the right is set as the second main pattern, either one can be set as the first main pattern.

[0111] In this embodiment, the main pattern 1 is formed by the light-transmitting portion 4 exposed on the transparent substrate 10, and the auxiliary pattern 2 is formed by the phase-shifting portion 5 exposed on the phase-shifting film 11 on the transparent substrate 10. In addition, the area other than the main pattern 1 and the auxiliary pattern 2 becomes the low-transmitting portion 3 on the transparent substrate 10 where at least a low-transmitting film 12 is formed.

[0112] In this embodiment, the low-transmittance portion 3 is formed by stacking a phase-shifting film 11 and a low-transmittance film 12 on a transparent substrate 10. The phase-shifting film 11 has a phase shift amount that shifts the exposure light of a representative wavelength in the wavelength range of the i-line to the g-line by approximately 180 degrees. In addition, the transmittance of the phase-shifting film 11 relative to the exposure light of the aforementioned representative wavelength is T1 (%).

[0113] The low-transmittance film 12 can have a specified low transmittance relative to the representative wavelength of the exposure light. In this embodiment, the low-transmittance film 12 can have a transmittance T2 (%) lower than that of the phase-shift film 11 relative to the representative wavelength of the exposure light in the wavelength range of the i-line to the g-line. Alternatively, the low-transmittance film 12 can also be formed as a light-shielding film that substantially does not transmit the exposure light.

[0114] Here, when a fine pattern (hole pattern) corresponding to the main pattern 1 of the photomask is formed on the transfer body by exposure using a photomask, if the diameter W1 of the main pattern 1 is set to 4 μm or less, a fine pattern with a diameter W2 (μm) (where W1 ≥ W2, more preferably W1 > W2) can be formed on the transfer body.

[0115] Specifically, the diameter W1 (μm) of the main pattern 1 is preferably 0.8 ≤ W1 ≤ 4.0, more preferably 1.0 ≤ W1 ≤ 3.5. Further, it can be set to 1.2 < W1 ≤ 3.0, and when a finer refinement is required, it can be set to 1.2 < W1 < 2.5.

[0116] Furthermore, the diameter W2 (μm) of the hole pattern formed on the transfer body as the transfer image of the main pattern 1 is preferably 0.8 ≤ W2 ≤ 3.0, more preferably 0.8 ≤ W2 ≤ 2.5, and even more preferably 0.8 ≤ W2 ≤ 2.0 or 0.8 ≤ W2 ≤ 1.8. Alternatively, it can be formed as 0.8 < W2 < 2.0 or 0.8 < W2 < 1.8. When a finer refinement is required, it can be formed as 0.8 < W2 < 1.5.

[0117] Furthermore, the photomask described in this embodiment can be used to form patterns of minute size that are useful for manufacturing display devices. For example, when the diameter W1 of the main pattern 1 is 3.0 (μm) or less, a more significant effect can be obtained.

[0118] However, in photomasks used to form hole patterns on the substrate (e.g., Reference Examples 1-3 above), it is advantageous to assign a mask bias β1 as described above. That is, if the diameter of the hole pattern on the photomask is set to W1 and the diameter of the hole pattern formed on the substrate is set to W2, it is also possible to form a pattern where W1 = W2, but it is preferable that W1 > W2. For example, if β1 (μm) is set as the bias value (W1-W2) and β1 > 0 (μm), then the bias value β1 (μm) is preferably 0.2 ≤ β1 ≤ 1.0, and more preferably 0.2 ≤ β1 ≤ 0.8. In this way, by defining the relationship between diameter W1 and diameter W2 as the bias value β1, advantageous effects such as reducing the loss of resist film thickness can be obtained on the substrate.

[0119] Furthermore, the main pattern 1 is composed of quadrilateral patterns, and the diameter W1 of the main pattern 1 is the dimension of one side of the quadrilateral. For example, if the main pattern 1 is a square pattern, then the diameter W1 of the main pattern 1 is the dimension of one side of the square; if the main pattern 1 is a rectangle pattern, then the diameter W1 is the dimension of the longer side. Additionally, the shape of the main pattern 1 is the shape seen from above. Furthermore, the diameter W2 of the hole pattern formed on the transfer body is the length of the largest portion of the distance between two opposing sides.

[0120] The mask bias β1 described above can also be applied to the photomask involved in this embodiment. In this embodiment, the two hole-forming patterns are formed at approximately a predetermined distance, thereby, there are cases where the size given as the mask bias β1 is larger than that of the isolated pattern (as described in Reference Examples 1 to 3 above).

[0121] Furthermore, for the photomask involved in this embodiment, there is a case where the positional relationship between the two hole-forming patterns preferably arranged close together is such that the mask bias has unequal dimensions relative to the X direction and the Y direction perpendicular to the X direction. Therefore, such a mask bias is set as β2, and the bias amounts given relative to the X direction and the Y direction perpendicular to it are set as β2(x) and β2(y), respectively. Details regarding the mask bias β2 will be described later.

[0122] The phase difference between the main pattern 1 and the auxiliary pattern 2 is relative to the representative wavelength of the exposure light used for exposing the photomask of this embodiment having the above-described transfer pattern. The phase difference is approximately 180 degrees. That is, the phase difference between the light representing the wavelength of the transmitted main pattern 1 and the light representing the wavelength of the transmitted auxiliary pattern 2. It is approximately 180 degrees. Approximately 180 degrees means 120 to 240 degrees. The aforementioned phase difference... The preferred temperature is 150–210 degrees Celsius.

[0123] Furthermore, the photomask of this embodiment is highly effective when using exposure light including at least one i-line, h-line, and g-line, and it is particularly preferable to use broad-wavelength light including i-line, h-line, and g-line as exposure light. In this case, any wavelength within the wavelength range of i-line to g-line can be used as a representative wavelength. For example, using h-line as a representative wavelength can construct the photomask of this embodiment. More preferably, the phase difference relative to the aforementioned representative wavelength is... for Spend.

[0124] In the photomask of this embodiment, in order to achieve the aforementioned phase difference, the main pattern 1 is a light-transmitting portion 4 formed by exposing the main surface of the transparent substrate 10, and the auxiliary pattern 2 is a phase-shifting portion 5 formed by exposing the phase-shifting film 11 formed on the transparent substrate 10. The phase shift of the phase-shifting film 11 relative to the aforementioned representative wavelength can be set to approximately 180 degrees.

[0125] The transmittance T1 of the phase-shifting portion 5 can be as follows. That is, if the transmittance of the phase-shifting film 11 formed on the phase-shifting portion 5 relative to the aforementioned representative wavelength is set as T1 (%), it is preferably 20 ≤ T1 ≤ 80, more preferably 30 ≤ T1 ≤ 75, and even more preferably 40 ≤ T1 ≤ 75. If the transmittance of the auxiliary pattern 2 is high, the width (d) of the auxiliary pattern can be reduced in order to obtain a specified amount of transmitted light. This provides the advantage of being able to obtain a degree of freedom in the arrangement of dense patterns that avoids mutual physical interference. On the other hand, if the transmittance T1 is slightly reduced and the width (d) of the auxiliary pattern is increased, there is an advantage of ease in the manufacturing of the pattern formation. In this case, the transmittance T1 is preferably 40 to 60 (%). Furthermore, the transmittance T1 (%) here is set as the transmittance of the aforementioned representative wavelength based on the transmittance of the transparent substrate 10 (100%).

[0126] In the photomask of this embodiment, a low-transmittance portion 3 is formed in the area outside the area where the main pattern 1 and the auxiliary pattern 2 are formed. Here, the main pattern 1 and the auxiliary pattern 2 are separated by the low-transmittance portion 3. The low-transmittance portion 3 can be formed with the following structure.

[0127] The low-transmittance section 3 is a low-transmittance film (i.e., a light-shielding film) 12 that substantially does not transmit light for exposure (light of a representative wavelength in the wavelength range of the i-line to the g-line), and can be formed on a transparent substrate 10 with an optical concentration OD≥2 (preferably OD≥3).

[0128] Alternatively, the low-transmittance portion 3 can also be formed as a low-transmittance film 12 that transmits exposure light within a specified range of transmittance. When transmitting exposure light within a specified range of transmittance, the transmittance T3 (%) of the low-transmittance portion 3 relative to the representative wavelength is compared to the transmittance T1 (%) of the phase-shifting portion 5 relative to the representative wavelength, where 0 < T3 < T1, preferably 0 < T3 ≤ 20. Here, if the phase-shifting portion 5 is not a single layer of the phase-shifting film 11, but rather a laminate of the phase-shifting film 11 and the low-transmittance film 12, the transmittance of this laminate is set as T3 (%). The transmittance T3 (%) here is also the same as above, set as the transmittance of the representative wavelength based on the transmittance of the transparent substrate 10.

[0129] Furthermore, in this way, when the low-transmittance film 12 transmits exposure light with a transmittance within a specified range, the phase shift amount in the stacked state of the phase shift film 11 and the low-transmittance film 12 is... Preferably, the phase difference is 90 degrees or less, and more preferably 60 degrees or less. "90 degrees or less" means that, in radians, the phase difference is "(2n-1 / 2)π to (2n+1 / 2)π (where n is an integer)". The phase difference is also the same as above, and is the phase difference relative to the representative wavelengths included in the exposure light.

[0130] Furthermore, the low-transmittance film 12 used as the photomask in this embodiment preferably has the following properties: it substantially does not transmit light of the aforementioned representative wavelength (OD≥2, more preferably OD>3), or it has a transmittance of less than 30% (T2%) (i.e., 0<T2<30) and a phase shift of... Approximately 180 degrees. Approximately 180 degrees means 120–240 degrees. Preferred phase shift amount. The temperature is 150 to 210 degrees Celsius.

[0131] The transmittance T2 (%) here is the same as above, and is set as the transmittance of the representative wavelength when the transmittance of the transparent substrate 10 is used as a reference.

[0132] In the transfer pattern involved in this embodiment, if the width of the auxiliary pattern 2 is set to d (μm), a significant effect can be obtained when the relationship of the following formula (1) holds.

[0133] 0.5≤√(T1 / 100)×d≤1.5···(1)

[0134] At this point, if the distance between the center of the main pattern 1 and the center of the auxiliary pattern 2 in the width direction is set as the slit spacing L (μm), it is preferably 1.0 < L ≤ 5.0, and more preferably 1.5 < L ≤ 4.5. However, the auxiliary pattern 2 constitutes at least a portion of the area of ​​the regular octagonal band surrounding the main pattern 1 via the low-transmittance portion 3. Therefore, the slit spacing L and the diameter W1 of the main pattern can be determined in a manner where the main pattern 1 and the auxiliary pattern 2 do not contact each other, that is, with the low-transmittance portion 3 sandwiched around the main pattern 1 and between it and the auxiliary pattern 2.

[0135] The width d (μm) of the auxiliary pattern 2 is set in the exposure conditions (exposure apparatus) applied to the photomask in this embodiment so as not to resolve the auxiliary pattern having transmittance T1. Specifically, the width d (μm) of the auxiliary pattern 2 is preferably d ≥ 0.7, more preferably d ≥ 0.8. Furthermore, compared to the width W1 (μm) of the main pattern 1, it is preferably d ≤ W1, more preferably d < W1.

[0136] Furthermore, regarding the width d (μm) of the auxiliary pattern 2, the relationship expressed in the above formula (1) is more preferably the following formula (1)-1, and even more preferably the following formula (1)-2.

[0137] 0.7≤√(T1 / 100)×d≤1.2···(1)-1

[0138] 0.75≤√(T1 / 100)×d≤1.0···(1)-2

[0139] The main pattern 1 of the transfer pattern in this embodiment has a quadrilateral shape. Specifically, the shape of the main pattern 1 is preferably a square or a rectangle. When the main pattern 1 is quadrilateral, the distance between the centroid of the quadrilateral and the center of the auxiliary pattern 2 in the width direction is called the slit spacing L.

[0140] In this embodiment, when a regular octagonal band of a predetermined width is defined around the main pattern 1, the auxiliary pattern 2 becomes at least a partial pattern constituting the regular octagonal band. A regular octagonal band refers to a shape whose outer and inner circumferences are both octagonal and of approximately a fixed width. For example... Figure 7 As shown, the auxiliary pattern 2 has a certain width outside its corners. A regular octagonal band with the auxiliary pattern 2 is defined and configured to surround the main pattern 1. Furthermore, the centroid of the regular octagonal band of the auxiliary pattern 2, which forms the inner and outer contours, is located at the same position as the centroid of the main pattern 1. In this embodiment, for ease of explanation, as shown... Figure 8 As shown, the aforementioned regular octagonal strip is divided into eight sections corresponding to the sides of the outer (or inner) octagon. Here, within these eight sections, [the following is a partial translation of the original text, which is incomplete and requires further context]. Figure 8 The rightmost block is designated as block A, the block above block A is designated as block H, and the block below block A is designated as block B. In other words, starting from block A, the blocks are designated as blocks B, C, D, E, F, G, and H in a clockwise direction.

[0141] As mentioned above Figure 4 As shown, in this embodiment, when the second main pattern 1b is positioned close to the first main pattern 1a, an auxiliary pattern 2a is arranged around the first main pattern 1a. The shape of the auxiliary pattern 2a is such that one of the eight blocks A to H constituting the regular octagonal band has a missing section on the side facing the second main pattern 1b. Specifically, as... Figure 7 As shown in (a), an auxiliary pattern 2a with a partial missing section of an octagonal band is arranged around the periphery of the first auxiliary pattern 1a. As illustrated, the auxiliary pattern 2a accompanying the first main pattern 1a has a missing shape in the right-hand section (corresponding to section A) facing the second main pattern 1b. Similarly, the auxiliary pattern 2b accompanying the second main pattern 1b also has a missing shape in one section (corresponding to section E) facing the first main pattern 1a. In other words, both main patterns have auxiliary patterns with missing octagonal band shapes in one section on opposite sides.

[0142] That is, when two hole-forming patterns are arranged at a proximity distance of less than a specified distance, the auxiliary patterns of each main pattern are missing between the two main patterns. Therefore, if the centers of gravity of the two main patterns (not shown) are connected by a straight line, the straight line does not cross the auxiliary patterns at all.

[0143] Furthermore, it is preferable to include the range S( ) between the mutually facing edges of the two main patterns. Figure 7 Within the area shown by the dashed line in (a), no auxiliary patterns are substantially arranged. However, when a portion of the auxiliary pattern partially enters the area S, it is preferable that this portion does not have an edge parallel to the mutually facing edges of the two main patterns. Figure 7 In the manner shown, the end of the auxiliary pattern enters the range S, but at that end there is only an edge that is inclined relative to the mutually facing edges of the two main patterns.

[0144] In addition, it is preferable that there are no island-shaped (shapes surrounded by closed straight lines or curves) auxiliary patterns within the range S.

[0145] More preferably, more than 90% of the area within the aforementioned range S is composed of low-transmittance portions. With such a configuration, the resist pattern shape of the two hole patterns formed on the transfer substrate is well-defined, suppressing the loss of resist film thickness.

[0146] If the auxiliary patterns 2a and 2b for the missing local blocks are configured in this way, then the above Figure 6 (b) shows the loss of resist film thickness caused by the recess 22, as Figure 9 The process is completed, resulting in a resist pattern shape with a well-defined profile. Furthermore, Figure 6 (b) and Figure 9 All cases involve a hole spacing P of 8 μm.

[0147] for Figure 6 As can be seen in (b), the allowable range of loss in resist film thickness can be determined based on the manufacturing conditions of the display device to be obtained using the photomask. If the initial film thickness (coating thickness) of the resist film is set to 100%, then a loss of 10% or less, more preferably 5% or less of the initial film thickness can be considered a good condition.

[0148] Therefore, in this embodiment, regarding whether to partially omit the auxiliary patterns 2a and 2b that accompany the closely adjacent main patterns 1a and 1b, the amount of resist film thickness loss can be determined in advance through experiments, simulations, etc., and the judgment can be made based on the result. Specifically, it is more useful to make the judgment in the following manner: if the resist film thickness loss exceeds, for example, 10%, the auxiliary patterns 2a and 2b are partially omitted; if it is less than 10%, the auxiliary patterns 2a and 2b are not omitted.

[0149] Furthermore, when the second main pattern 1b is positioned close to the first main pattern 1a, and the distance D between the auxiliary patterns 2a and 2b is (refer to...) Figure 4 When the distance D between the auxiliary patterns 2a and 2b is 1.0 μm or less, it is desirable to omit the block (block A mentioned above) of the auxiliary pattern 2a surrounding the first main pattern 1a that faces the second main pattern 1b. Similarly, in the second main pattern 1b, it is also preferable to form an auxiliary pattern 2b that omits the block (block E mentioned above) facing the first main pattern 1a. Furthermore, it is more preferable that the omission of the block is applied when the distance D between the auxiliary patterns 2a and 2b is 1.5 μm or less.

[0150] The above examples are based on the resolving performance of the exposure apparatus for display devices.

[0151] In addition, such as Figure 4 As shown, the distance between auxiliary patterns refers to the distance between opposite blocks (the length of the perpendicular line). Therefore, as illustrated, when two main patterns 1a and 1b are arranged adjacent to each other in a certain direction, and each main pattern 1a and 1b is surrounded by corresponding (attached) auxiliary patterns 2a and 2b, the distance between the opposite (facing) edges of the auxiliary patterns 2a and 2b in the direction of arrangement of the two main patterns 1a and 1b is called the distance D between the auxiliary patterns.

[0152] Furthermore, when the distance between the centroids of the main patterns 1a and 1b, i.e., the aperture spacing P, is 1.6 μm or more, preferably 3 μm or more, the photomask of this embodiment can achieve the significant effects of the present invention. If the aperture spacing P is too small, there are risks such as: insufficient residual film amount of the resist pattern formed at the position corresponding to the two main patterns; and adverse situations such as the mask offset β2 being too large, which makes pattern design difficult, as will be described later.

[0153] The optical simulations involved in the embodiments and reference examples of the present invention will be described below.

[0154] Figure 10 This is a top view schematic diagram showing the main parts of the transfer pattern of the photomask in the reference example. Figure 10 (a) shows reference example 4. Figure 10 (b) shows reference example 5. Figure 10 (c) shows reference example 6. Figure 10 (d) shows reference example 7. Figure 10 (e) shows reference example 8. Figure 11 This is a top view schematic diagram showing the main part of the transfer pattern of a photomask according to an embodiment of the present invention. Figure 11 (f) shows Example 1. Figure 11(g) shows Example 2, Figure 11 (h) shows Example 3, Figure 11 (i) shows Example 4.

[0155] in addition, Figure 10 (a) shows the hole spacing P of the main patterns 1a and 1b (refer to) Figures 5-7 The value is 16μm, and there are no missing blocks in the auxiliary patterns 2a and 2b of the regular octagonal band. Figure 10 (b) shows the case where the aperture spacing P of the main patterns 1a and 1b is 12 μm, and there are no missing blocks in the auxiliary patterns 2a and 2b. Additionally, Figure 10 (c) shows the case where the aperture spacing P of the main patterns 1a and 1b is 9 μm and there are no missing blocks in the auxiliary patterns 2a and 2b. Figure 10 (d) shows the case where the aperture spacing P of the main patterns 1a and 1b is 8.75 μm and there are no missing blocks in the auxiliary patterns 2a and 2b. Figure 10 (e) shows the case where the aperture spacing P of the two main patterns 1a and 1b is 8.75 μm, and a block of each of the auxiliary patterns 2a and 2b is combined to make them common.

[0156] on the other hand, Figure 11 (f) shows the case where the aperture spacing P of the main patterns 1a and 1b is 8.75 μm, and the auxiliary patterns 2a and 2b are missing a block. Figure 11 (g) shows the case where the aperture spacing P of the main patterns 1a and 1b is 8 μm, and one block of the auxiliary patterns 2a and 2b is missing. Additionally, Figure 11 (h) shows the case where the aperture spacing P of the main patterns 1a and 1b is 7.5 μm, and the auxiliary patterns 2a and 2b are missing a block. Figure 11 (i) shows the case where the aperture spacing P of the main patterns 1a and 1b is 7μm and the auxiliary patterns 2a and 2b are missing three blocks.

[0157] In addition, the above will be used in this simulation. Figure 2 Taking the photomask (binary mask) shown in (a) as Reference Example 1, the above-described photomask will be used. Figure 2 The photomask (halftone phase-shift mask) shown in (b) is taken as Reference Example 2. The main patterns applied to Reference Example 1 and Reference Example 2 are both isolated patterns without auxiliary patterns.

[0158] Optical simulations were performed on the patterns of the aforementioned photomasks, and the results were obtained. Figure 12 The results are as shown. In this simulation, in addition to Reference Example 1 and Reference Example 2, the above-mentioned results are used. Figure 2 The exposure energy used for the transfer of the main pattern (isolated pattern) shown in (c) is 80 mJ / cm.2 Based on the Dose (Eop Dose), the resist pattern formed on the substrate is evaluated when applying this Dose. Furthermore, "panel X-CD" and "panel Y-CD" are the dimensions in the X and Y directions of the hole patterns formed on the substrate corresponding to the main pattern of the photomask. In addition, in each reference example and embodiment, the target dimensions of X-CD and Y-CD are set to 1.5 μm.

[0159] First of all, Figure 10 In Reference Example 4 (a), the two main patterns 1a and 1b are fully separated; therefore, each main pattern 1a and 1b essentially acquires the optical properties of an isolated pattern. This aspect is... Figure 10 Reference Example 5 for (b) Figure 10 (c) is also the same as in Reference Example 6. On the other hand, as Figure 10 As in Reference Example 7 (d), if the two main patterns 1a and 1b are close together and the aperture spacing P is narrowed to 8.75 μm, then the distance D between the auxiliary patterns 2a and 2b becomes 0.95 μm. In this case, the loss of resist film thickness exceeds 12%.

[0160] Here, as Figure 10 As in Reference Example 8 of (e), even when the auxiliary patterns 2a and 2b of the main patterns 1a and 1b that are close to each other are partially combined into one (block) and made common, the loss of resist film thickness is close to 12%, with little improvement.

[0161] According to the inventors' research, this problem is believed to be related to photoresists used in the manufacture of display devices. Specifically, the photoresists used in the manufacture of display devices (positive photoresists) are different from those used in the manufacture of semiconductor devices and are designed to have higher sensitivity. Therefore, even with relatively low dosing, corresponding film reduction is not avoided, and localized film thickness losses can easily occur in undesirable areas.

[0162] Furthermore, regarding the interaction between the main pattern 1 and the auxiliary pattern 2 generated by the photomask in Reference Example 3, the optical image formed by the light with the reversed phase transmitted from the auxiliary pattern 2 enhances the peak intensity of the transmitted light from the main pattern 1. Moreover, it is possible to obtain... Figure 3 The excellent transfer performance (DOF, MEEF) is shown. On the other hand, the light intensity of the light transmitted through the auxiliary pattern is also slightly increased through interaction with the main pattern 1. It is believed that, apart from the case where the auxiliary patterns 2 are close to each other due to their high sensitivity, if the auxiliary pattern 2 is shared by multiple main patterns 1, there is a risk that the thickness of the resist on the substrate will be reduced due to the transmitted light of the auxiliary pattern 2.

[0163] On the other hand, Figure 11 In embodiment 1 of (f), one block of the eight blocks constituting the regular octagonal band surrounding the first main pattern 1a, facing the second main pattern 1b, is missing, and an auxiliary pattern 2a with the remaining seven blocks is arranged around the periphery of the first main pattern 1a. That is, the auxiliary pattern 2a is shaped such that the block of the regular octagonal band surrounding the periphery of the first main pattern 1a that is closest to and faces the regular octagonal band surrounding the periphery of the second main pattern 1b is missing. Similarly, the second main pattern 1b is also treated similarly, with one block facing the first main pattern 1a missing, and the auxiliary pattern 2b with the remaining seven blocks arranged around the periphery of the second main pattern 1b.

[0164] Furthermore, when making the auxiliary pattern's blocks missing, it is not necessarily necessary to follow... Figure 8 The shown block boundaries are cut off, for example, as Figure 7 As shown in (a), at least the main part of the block needs to be missing. Regarding the area of ​​the missing portion, for example, if one of the eight blocks is missing, it should be at least 80% of the area corresponding to one block; more preferably, it should be at least 80% of the area corresponding to the number of missing blocks. In this case, a portion with only the low-transmittance portion 3 is sandwiched between the two main patterns, and the straight line connecting the centers of gravity of the two main patterns 1a and 1b does not cross the auxiliary pattern.

[0165] Thus, it can be seen that in the resist pattern formed by eliminating the facing blocks in the auxiliary patterns of two closely spaced main patterns, the loss of resist film thickness is zero, significantly reducing losses and achieving remarkable results. Furthermore, it can be seen that similar effects are achieved as follows... Figure 11 Example 2 of (g) Figure 11 As in Example 3 (h), it is also possible to obtain the same result by further bringing the two main patterns 1a and 1b closer together (with hole spacing P = 8 μm and P = 7.5 μm). The cross-sectional structure of the resist pattern in this case is similar to... Figure 9 same.

[0166] However, in Figure 11 In the embodiments (f) to (i), although the same exposure dose as in Reference Examples 4 to 8 above is used, the diameter of the hole pattern transferred to the resist film is slightly smaller than the initial target size. Specifically, in Example 1, relative to the initial target size of 1.5 (μm), the X-CD (diameter in the X direction) becomes 1.39 (μm) and the Y-CD (diameter in the Y direction) becomes 1.37 (μm). Therefore, in order to form the hole pattern, it is desirable that the mask offset β1 be greater than 0.5 μm in order to make the X-CD and Y-CD on the substrate close to the target size (1.5 μm).

[0167] Furthermore, in order to set the X-CD and Y-CD on the transfer body to be of equal target size (1.5μm), it is preferable to assign appropriate mask bias β2 to the X and Y directions respectively.

[0168] Therefore, as Figure 12 As shown, in Figure 11 In the embodiments (f) to (h), appropriate mask biases β2(x) and β2(y) are applied relative to the CD on the mold, thereby obtaining the target size of 1.5 μm for both X-CD and Y-CD on the transfer body.

[0169] Furthermore, the result is that it can be known that in Figure 11 In the case of the photomask of embodiments (f) to (h), the value of DOF (depth of focus) (24) is greater than that of the binary mask of Reference Example 1. Figure 2 (a) and the halftone phase shift mask of Reference Example 2 ( Figure 2 (b) enables the stable formation of hole patterns of the desired diameter on the substrate. Furthermore, the oop dose required for exposure is smaller compared to the binary mask of Reference Example 1 and the halftone phase-shift mask of Reference Example 2, thus enabling efficient exposure processes.

[0170] In addition, Figure 11 In embodiments (f) to (h), one of the eight blocks of the auxiliary pattern 2a accompanying the first main pattern 1a and the eight blocks of the auxiliary pattern 2b accompanying the second main pattern 1b, respectively, is missing from each other. In other words, for a main pattern 1, the number of blocks in the auxiliary pattern 2 is set to seven. On the other hand, when the two main patterns 1a and 1b are arranged closer together, the blocks located on both sides of the already missing block can be further missing, centered on the missing block. For example, in Figure 11 In embodiment 4 of (i), block A and blocks B and H on either side of the auxiliary pattern 2a accompanying the first main pattern 1a are missing, and block E and blocks D and F on either side of the auxiliary pattern 2b accompanying the second main pattern 1b are missing, thereby reducing the loss of resist film thickness to zero. As a result, here, three blocks are missing for one main pattern 1, thus setting the number of blocks in the auxiliary pattern 2 to five. Furthermore, the number of main patterns arranged close to each other is not limited to two; a greater number of hole-forming patterns can be arranged at close distances, and in this case, the missing blocks can also be designed in the same manner as described above.

[0171] In a pattern group comprising multiple main patterns arranged in close proximity (each close to at least one of the others), when the number of main patterns is set to N and the total number of blocks of auxiliary patterns is set to K, it is possible to form a pattern such that K≤(8-1)N.

[0172] In addition, Figure 11 In (f) to (i), only the case where the second main pattern 1b is close to the first main pattern 1a in the X direction (left-right direction of the figure) is illustrated, but the case where it is close in the Y direction is the same as described above, and it is possible to configure an auxiliary pattern 2 that makes any one of the eight blocks missing.

[0173] Furthermore, the present invention can also be effectively applied in cases where the second main pattern 1b approaches the first main pattern 1a diagonally relative to the main pattern 1, or when they approach at an angle. In this case, it is sufficient to omit at least one of the eight blocks of the auxiliary pattern 2a accompanying the first main pattern 1a on the side facing the second main pattern 1b.

[0174] Furthermore, when the third main pattern, and further, the fourth main pattern, is arranged close to the first main pattern, it is also possible, in the same manner as described above, to omit the blocks on the opposite side of the eight blocks of the auxiliary patterns accompanying each main pattern. In this case, through the relative arrangement of multiple main patterns, in addition to main patterns with auxiliary patterns having seven blocks and main patterns with auxiliary patterns having five blocks, there can also be main patterns with auxiliary patterns having six blocks, four blocks, three blocks, two blocks, and further, one block.

[0175] For example, a pattern group can be formed with two main patterns having auxiliary patterns that are each missing one block, or a pattern group having auxiliary patterns that are each missing three blocks.

[0176] Alternatively, the three main patterns, through their arrangement (in the X direction, Y direction, or both X and Y directions, hereinafter the same), can form a pattern group with auxiliary patterns that are missing one or two blocks respectively. Furthermore, the four main patterns, through their arrangement, can also form a pattern group with auxiliary patterns that are missing one to five blocks respectively.

[0177] The following five, six, or seven main patterns are arranged to form a group of auxiliary patterns that are missing one to six blocks respectively, or eight main patterns can be arranged to form a group of auxiliary patterns that are missing one to seven blocks respectively.

[0178] On the other hand, the auxiliary patterns of a main pattern can be formed as blocks that are not missing on the side facing other main patterns, or blocks on either side of them.

[0179] Furthermore, there exists a situation where, corresponding to the proximity direction of multiple hole-forming patterns, the diameter of the hole pattern formed on the transfer body has different values ​​in the X and Y directions. This is because the change in the optical image caused by the absence of local blocks of the auxiliary pattern is uneven relative to the X and Y directions. Therefore, to compensate for the effect of uneven optical images in the X and Y directions, it is useful to assign mask bias β2 of different sizes in the X and Y directions to the pattern depiction data.

[0180] For example, as mentioned above Figure 7 As shown in (a), when the first main pattern 1a and the second main pattern 1b are arranged in the X direction and the mutually facing blocks (i.e., the blocks that extend in the Y direction) in the auxiliary patterns 2a and 2b that accompany the two main patterns 1a and 1b are missing, with regard to the mask offset β2 (μm) assigned to the size of the first main pattern 1a and the second main pattern 1b, when the amount assigned in the X direction is set to β2 (x) and the amount assigned in the Y direction is set to β2 (y), it is possible to form β2 (y) > β2 (x).

[0181] Specifically, observing from the main pattern, the direction relative to the missing part with auxiliary patterns (in) Figure 7 In (a), the direction perpendicular to the X direction (in) Figure 7 In (a), a positive bias β2(y) is assigned to the Y direction. Furthermore, as needed, the direction of the missing portion with the auxiliary pattern (in...) can be... Figure 7 In (a), a negative bias β2(x) is assigned to the X direction.

[0182] Thus, in Figure 13 The example illustrates a transfer pattern including a photomask with main patterns 1a and 1b having a mask bias β2. Here, the result of adding the mask bias β2 is that the size of the main patterns 1a and 1b in the X direction is smaller than the size in the Y direction, and the shape of the main patterns 1a and 1b becomes a long rectangle.

[0183] exist Figure 11 In embodiment (g), the hole pattern formed on the transfer substrate as a transfer image of the main square patterns 1a and 1b is a horizontally elongated rectangle (X-CD = 1.40 μm, Y-CD = 1.37 μm). Therefore, if the main patterns 1a and 1b are shaped into vertically elongated rectangles by applying a mask bias, the error in pattern size caused by the absence of local blocks of the auxiliary patterns 2a and 2b can be eliminated. As a result, a hole pattern with equal dimensions in the X and Y directions can be formed on the transfer substrate.

[0184] Therefore, by optical simulation, the offset β2 used to make the dimensions in the X and Y directions equal on the transfer body can be determined, and this offset can be reflected in the pattern drawing data.

[0185] Therefore, in the transfer pattern of the photomask, the main pattern with bias β2 becomes a rectangle. That is, the first main pattern becomes a rectangle with a long side on the side facing the second main pattern which is in a close position.

[0186] Regarding the above Figure 13 In such an arrangement example, the long side W3(y) of the main pattern becomes W3(y) = W1 + β2(y), and the short side W3(x) becomes W3(x) = W1 + β2(x). Moreover, W3(x) and W3(y) preferably satisfy the following formula.

[0187] The longer side is 0.8≤W3(y)≤4.0, and more preferably 1.0≤W3(y)<3.5.

[0188] The shorter side is 0.8≤W3(x)≤4.0, and more preferably 1.0≤W3(x)≤3.0.

[0189] As described above, when the photomask of this embodiment is used as a photomask for manufacturing a display device, that is, when the photomask of this embodiment is used in combination with a photoresist for manufacturing a display device, the loss of resist film thickness in the portion of the transfer body corresponding to the auxiliary pattern can be significantly reduced.

[0190] <Methods for Manufacturing Photomasks>

[0191] Next, an example of a method for manufacturing a photomask that can be applied to embodiments of the present invention will be referred to below. Figure 14 Explanation will be given for (a) to (f). Furthermore, in Figure 14 In (a) to (f), a cross-sectional view is shown on the left and a top view is shown on the right. For simplicity, the photomask pattern shape shows only the first main pattern and the auxiliary pattern accompanying the first main pattern.

[0192] First, such as Figure 14 As shown in (a), a photomask blank 30 is prepared. In this photomask blank 30, a phase-shifting film 11 and a low-transmittance film 12 are sequentially formed on a transparent substrate 10 made of glass or the like, and a first photoresist film 13 is further coated on it.

[0193] A phase-shifting film 11 is formed on the main surface of the transparent substrate 10. For the phase-shifting film 11, when any one of the i-line, h-line, or g-line is used as the representative wavelength of the exposure light, the transmittance T1 (%) relative to that representative wavelength is preferably 20–80 (%), more preferably 30–75 (%), and even more preferably 40–75 (%). Furthermore, the phase shift of the phase-shifting film 11 relative to the aforementioned representative wavelength is approximately 180 degrees. With such a phase-shifting film 11, the phase difference of the transmitted light between the main pattern formed by the light-transmitting portion and the auxiliary pattern formed by the phase-shifting portion can be set to approximately 180 degrees. Such a phase-shifting film 11 shifts the phase of light within the wavelength range of the i-line to g-line by approximately 180 degrees. As a method for forming the phase-shifting film 11, known methods such as sputtering can be used.

[0194] The phase-shifting film 11 is expected to satisfy the aforementioned transmittance and phase difference, and is formed from a material capable of wet etching, as described below. However, if the amount of side etching produced during wet etching is too large, adverse conditions such as deterioration of CD accuracy and damage to the upper film due to undercut will occur. Therefore, the film thickness of the phase-shifting film 11 is set to... The following are better, preferably More preferably

[0195] In addition, in order to meet these conditions, the refractive index of the representative wavelength (e.g., h-line) included in the exposure light of the phase shift film 11 material is preferably 1.5 to 2.9, more preferably 1.8 to 2.4.

[0196] Furthermore, in order to fully utilize the phase shift effect, it is preferable that the patterned cross section (etched surface) generated by wet etching is perpendicular to the main surface of the transparent substrate 10.

[0197] Considering the above properties, the material used as the phase shift film 11 can be a material containing any one of Zr, Nb, Hf, Ta, Mo, Ti and Si, or an oxide, nitride, oxynitride, carbide or oxynitride carbide containing these materials.

[0198] A low-transmittance film 12 is formed on the phase-shifting film 11. The method for forming the low-transmittance film 12 is the same as that for the phase-shifting film 11, and known methods such as sputtering can be used. Furthermore, it is preferable that the wavelength-dependent variation of the phase shift amount of the phase-shifting film 11 is within 40 degrees relative to the i-line, h-line, and g-line.

[0199] The low-transmittance film 12 can be made of a light-shielding film that substantially does not transmit light for exposure. Alternatively, it can be made of a film with a predetermined low transmittance relative to the representative wavelength of the light for exposure. The low-transmittance film 12 used in the manufacture of the photomask of this embodiment has a transmittance T2 (%) lower than that of the phase-shifting film 11 relative to light of a representative wavelength in the wavelength range of the i-line to the g-line.

[0200] When the low-transmittance film 12 transmits exposure light with low transmittance, it is desirable that the transmittance and phase shift of the low-transmittance film 12 relative to the exposure light achieve the transmittance and phase shift of the low-transmittance portion of the photomask of this embodiment. Preferably, in the stacked state of the phase shift film 11 and the low-transmittance film 12, the transmittance T3 (%) relative to the representative wavelength of the exposure light is T3 ≤ 20, and the phase shift is... Preferably, the temperature is 90 degrees or less, and more preferably 60 degrees or less.

[0201] As a separate property of the low-transmittance film 12, it is preferable that it substantially does not transmit light of the aforementioned representative wavelengths, or has a transmittance of less than 30% (T2%) (i.e., 0 < T2 < 30), and a phase shift amount Approximately 180 degrees. Approximately 180 degrees means 120–240 degrees. Preferred phase shift amount. The temperature is 150 to 210 degrees Celsius.

[0202] The material of the low-transmittance film 12 can also be Cr or its compounds (oxides, nitrides, carbides, oxynitrides, or oxynitride carbides), or it can be a silicide containing Mo, W, Ta, or Ti, or a compound of the aforementioned silicide. The material of the low-transmittance film 12, like the phase-shifting film 11, is capable of wet etching, and preferably is a material with etching selectivity relative to the material of the phase-shifting film 11. That is, it is desirable that the low-transmittance film 12 is resistant to the etchant of the phase-shifting film 11, and the phase-shifting film 11 is resistant to the etchant of the low-transmittance film 12.

[0203] A first photoresist film 13 is coated on the low-transmittance film 12. The photomask of this embodiment is preferably drawn by a laser drawing apparatus, thereby becoming a photoresist suitable for the laser drawing apparatus. The photoresist constituting the first photoresist film 13 can be either positive or negative; it will be described below as a positive photoresist.

[0204] Next, as Figure 14As shown in (b), a drawing apparatus is used to draw the first photoresist film 13 according to drawing data based on a transfer pattern (first drawing). Furthermore, using the first photoresist pattern 13p obtained through development as a mask, a low-transmittance film 12 is wet-etched to form a low-transmittance film pattern 12p. In this stage, the area designated as the low-transmittance portion is defined, and the area of ​​the auxiliary pattern (low-transmittance film pattern 12p) surrounded by the low-transmittance portion is also defined. The etchant (wet etchant) used for wet etching can be a known etchant suitable for the composition of the low-transmittance film 12. For example, if the low-transmittance film 12 is a Cr-containing film, cerium diammonium nitrate or the like can be used as the wet etchant.

[0205] Next, as Figure 14 As shown in (c), the first resist pattern 13p is stripped. As a result, the low-transmittance film pattern 12p and the phase-shifting film 11 are partially exposed.

[0206] Next, as Figure 14 As shown in (d), a second photoresist film 14 is coated on the entire surface including the low-transmittance film pattern 12p.

[0207] Next, as Figure 14 As shown in (e), after a second pattern is created relative to the second photoresist film 14, a second resist pattern 14p is formed by development. Next, the phase shift film 11 is wet-etched using the second resist pattern 14p and the low-transmittance film pattern 12p as a mask. Through this etching (development), the main surface of the transparent substrate 10 is exposed as a light-transmitting portion, thereby defining the area of ​​the main pattern formed by the light-transmitting portion.

[0208] Furthermore, the second resist pattern 14p covers the area that serves as the auxiliary pattern and has an opening within the area of ​​the main pattern formed by the light-transmitting portion. In this case, it is preferable to apply the resist relative to the drawing data of the second drawing, such that the edge portion of the low-transmittance film pattern 12p is exposed inside the opening edge of the second resist pattern 14p. This absorbs the alignment misalignment that occurs between the first and second drawings, thereby preventing a deterioration in the CD accuracy of the transfer pattern.

[0209] That is, if the second resist pattern 14p is applied during the second drawing process, the pattern imprinting of the phase-shifting film 11 and the low-transmittance film 12 will not experience positional shift when forming isolated hole patterns on the transfer substrate. Therefore, in Figure 1 In the example of the transfer pattern, the center of gravity of the main pattern 1 and the auxiliary pattern 2 can be made to be precisely aligned.

[0210] The wet etchant used for etching the phase shift film 11 is appropriately selected in accordance with the composition of the phase shift film 11.

[0211] Next, as Figure 14 As shown in (f), the second resist pattern 14p is peeled off. Thus, a photomask with a transfer pattern is completed. Furthermore, in Figure 14 The diagram illustrates the case where an auxiliary pattern forms a regular octagon without any missing blocks, but in the case where any one of the eight blocks is missing, ... Figure 14 When defining the range of the auxiliary pattern in (b), the drawing data can be changed accordingly to the position and size of the missing block.

[0212] In the fabrication of the aforementioned photomask, for the etching used in patterning optical films such as phase-shifting film 11 and low-transmittance film 12, there are dry etching and wet etching methods. While either of these etching methods can be used, wet etching is particularly advantageous in this invention. This is because photomasks used in display device manufacturing are relatively large and come in various sizes. If dry etching, which requires a vacuum chamber, is applied when manufacturing such a photomask, it leads to the large-scale operation of the dry etching equipment and a reduction in the efficiency of the manufacturing process.

[0213] However, there are also challenges associated with wet etching when manufacturing such photomasks. Because wet etching is isotropic, it involves etching the film along the depth direction to dissolve it, and also etching in a direction perpendicular to the depth direction. For example, when etching a phase-shifting film 11 with a thickness of F (nm) to form a slit, the opening of the resist pattern that becomes the etching mask is 2F (nm) smaller than the desired slit width (i.e., F (nm) smaller on one side). However, the finer the slit width, the more difficult it is to maintain the dimensional accuracy of the resist pattern opening. Therefore, it is more useful for the width d of the auxiliary pattern to be 1 μm or more, preferably 1.3 μm or more.

[0214] Furthermore, when the film thickness F (nm) is relatively large, the amount of side etching also increases. Therefore, it is advantageous to use a film material with a phase shift of approximately 180 degrees even when the film thickness is small. Thus, it is desirable for the refractive index of the phase-shifting film 11 to be relatively high relative to the representative wavelength of the exposure light. Specifically, it is preferable to form the phase-shifting film 11 using a material with a refractive index of 1.5 to 2.9, more preferably 1.8 to 2.4, relative to the aforementioned representative wavelength.

[0215] The present invention includes a method for manufacturing a display device, which includes a step of using a photomask of this embodiment, exposing the image using an exposure device, and transferring the above-mentioned transfer pattern onto a transfer object.

[0216] In the manufacturing method of the display device of the present invention, firstly, a photomask of this embodiment is prepared. Next, using an exposure apparatus having a numerical aperture (NA) of 0.08 to 0.15 and an exposure light source including i-lines, h-lines, and g-lines, the above-mentioned transfer pattern is exposed to form a hole pattern with a diameter W2 of 0.8 to 3.0 (μm) on the transfer substrate. It is generally advantageous to use equal-multiplication exposure.

[0217] When transferring a pattern for transfer using the photomask of this embodiment, a reduced exposure can also be used. However, the exposure machine used for the photomask for manufacturing a display device is preferably an exposure machine that performs equal-multiplied projection exposure.

[0218] For example, it is desirable that the numerical aperture (NA) of the optical system is 0.08 ≤ NA < 0.20, more preferably 0.08 ≤ NA ≤ 0.15, and even more preferably 0.08 < NA < 0.15. Furthermore, the coherence factor σ is 0.4 ≤ σ ≤ 0.9, more preferably 0.4 < σ < 0.7, and even more preferably 0.4 < σ < 0.6.

[0219] The light source used for exposure includes at least one of the i-line, h-line, and g-line. When using exposure light of a single wavelength, the i-line is preferred. On the other hand, using a light source that includes all three wavelengths (i-line, h-line, and g-line) is useful in ensuring sufficient light intensity.

[0220] In addition, the light source of the exposure device used can also be oblique illumination (ring illumination, etc.), but the excellent effects of the present invention can be fully obtained by using ordinary illumination without oblique illumination.

[0221] According to the present invention, in the manufacturing method of a display device using a display device manufacturing mold, even fine, dense patterns can be stably transferred to the substrate. Specifically, it ensures the process margin during the manufacturing of DOF, MEEF, etc., and accurately forms the hole pattern. Furthermore, when forming the dense pattern, the thickness of the resist pattern formed on the substrate can be sufficiently ensured. This improves CD accuracy in display device production, thereby providing industrial benefits such as stable production and high yield.

Claims

1. A photomask for manufacturing a display device, having a transfer pattern on a transparent substrate, characterized in that, The transfer pattern includes: The main pattern is composed of translucent parts; An auxiliary pattern, which is composed of phase-shifted portions disposed around the periphery of the main pattern; and a low-transmittance portion, which is formed in an area other than the main pattern and the auxiliary pattern. The auxiliary pattern is arranged around the main pattern, following its surroundings. The phase difference between the main pattern and the auxiliary pattern is 120 to 240 degrees. When one of the multiple main patterns included in the transfer pattern is designated as the first main pattern, a second main pattern, different from the first main pattern, is positioned close to the first main pattern. The auxiliary pattern accompanying the first main pattern has a missing part on the side facing the second main pattern. The phase-shifting portion is formed by forming a phase-shifting film on the transparent substrate. The refractive index of the representative wavelengths included in the exposure light for the phase-shift film is 1.5–2.

9. The phase-shifting film has a transmittance T1 of 20% to 80% relative to the representative wavelength of the exposure light, and the phase-shifting film shifts the phase of the exposure light by 120 to 240 degrees.

2. The photomask for manufacturing a display device according to claim 1, characterized in that, When the diameter of the main pattern is set to W1, the transfer pattern forms a hole pattern with a diameter of W2 on the object to be transferred as the transfer image of the main pattern, where W1 ≥ W2.

3. The photomask for manufacturing a display device according to claim 1, characterized in that, When the arrangement direction of the first main pattern and the second main pattern is set to the X direction, the size of the first main pattern in the X direction is smaller than the size of the first main pattern in the Y direction, which is perpendicular to the X direction.

4. The photomask for manufacturing a display device according to any one of claims 1 to 3, characterized in that, The transfer pattern includes three or more main patterns arranged in a dense pattern in the X direction, in the Y direction perpendicular to the X direction, or in both the X and Y directions. For each of the main patterns constituting the dense pattern, the transfer pattern has at least one missing auxiliary pattern on the side facing the other main patterns.

5. The photomask for manufacturing a display device according to any one of claims 1 to 3, characterized in that, The low-transmittance part is a light-shielding part with an optical concentration (OD) of 2 or more relative to the exposure light.

6. The photomask for manufacturing a display device according to any one of claims 1 to 3, characterized in that, The transfer pattern is formed by patterning an optical film formed on the main surface of the transparent substrate, and the light-transmitting portion is formed by exposing the main surface.

7. The photomask for manufacturing a display device according to any one of claims 1 to 3, characterized in that, The auxiliary pattern accompanying the second main pattern has a missing part on the side facing the first main pattern.

8. The photomask for manufacturing a display device according to any one of claims 1 to 3, characterized in that, The straight line connecting the centroid of the first main pattern and the centroid of the second main pattern does not cross the auxiliary pattern.

9. The photomask for manufacturing a display device according to any one of claims 1 to 3, characterized in that, The main pattern is a hole pattern.

10. The photomask for manufacturing a display device according to any one of claims 1 to 3, characterized in that, The thickness of the phase-shifting film is 11. The photomask for manufacturing a display device according to any one of claims 1 to 3, characterized in that, The distance between the centroids of the first main pattern and the second main pattern is greater than 1.6 μm.

12. The photomask for manufacturing a display device according to any one of claims 1 to 3, characterized in that, The distance between the centroids of the first main pattern and the second main pattern is less than 8.75 μm.

13. A method for manufacturing a display device, characterized in that, include: The process of preparing the photomask according to any one of claims 1 to 12; and The process of using an exposure device to expose the transfer pattern to form a hole pattern on the substrate.

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