JP6808665B2 - Photomask for manufacturing display devices and manufacturing method for display devices - Google Patents

Description

The present invention relates to a photomask for manufacturing an electronic device, and particularly suitable for use in manufacturing a display device (flat panel display, FPD).

Patent Document 1 describes a photomask that is suitable for the exposure environment of a mask for manufacturing a display device and can stably transfer a fine pattern.

Further, Patent Document 2 describes a method for simultaneously miniaturizing an isolated pattern and a dense pattern with respect to a photomask for forming a fine pattern used in manufacturing a semiconductor integrated circuit device.

Japanese Unexamined Patent Publication No. 2016-0242664 Japanese Unexamined Patent Publication No. 2006-338057

Display devices including liquid crystal displays and EL (Organic ElectroLuminescence) display devices are expected to be brighter, save power, and improve display performance such as high-definition, high-speed display, and wide viewing angle. It is rare.

For example, in the case of a thin film transistor (“TFT”) used in the above display device, among a plurality of patterns constituting the TFT, the contact holes formed in the interlayer insulating film are surely the patterns of the upper layer and the lower layer. Correct operation cannot be guaranteed unless it has the effect of connecting. On the other hand, for example, in order to make the aperture ratio of the liquid crystal display device as large as possible to make it a bright and power-saving display device, the diameter of the contact hole is required to be sufficiently small, and the density of the display device is increased. With the demand, the diameter of the hole pattern is also desired to be finer (for example, less than 3 μm). For example, a hole pattern having a diameter of 0.8 μm or more and 2.5 μm or less, and further a diameter of 2.0 μm or less is required, and specifically, a pattern having a diameter of 0.8 to 1.8 μm is also desired. it is conceivable that.

By the way, in the field of photomasks for manufacturing semiconductor devices (LSIs), which have a higher degree of integration and remarkably miniaturized patterns than display devices, the exposure device has a high numerical aperture in order to obtain high resolution. There is a history that the wavelength of the exposure light has been shortened by applying an optical system having a numerical aperture of several NA (for example, 0.2 or more). As a result, KrF and ArF excimer lasers (single wavelengths of 248 nm and 193 nm, respectively) have come to be widely used in this field.

On the other hand, in the field of lithography for manufacturing display devices, it is not common that the above method is applied in order to improve the resolution. For example, the NA (numerical aperture) of the optical system of the exposure apparatus used in this field is about 0.08 to 0.12, and even in the future, it is 0.20 or less, for example, 0.08 to 0. There is an environment where about 15 is applied. In addition, i-line, h-line, or g-line is often used as the exposure light source, and by mainly using a broad wavelength light source containing these, the amount of light for irradiating a large area can be obtained, and production efficiency and cost can be improved. There is a strong tendency to emphasize.

Also, in the manufacture of display devices, there is an increasing demand for pattern miniaturization as described above. Here, there are some problems in applying the technology for manufacturing a semiconductor device as it is to the manufacturing of a display device. For example, the conversion to a high resolution exposure device having a high numerical aperture (NA) requires a large investment and is inconsistent with the price of the display device. In addition, when changing the exposure wavelength (using a short wavelength such as an ArF excimer laser with a single wavelength), if it is applied to a display device with a large area, production efficiency will decrease and considerable investment will still be required. It is inconvenient in that. In other words, the problem with photomasks for manufacturing display devices is that while pursuing unprecedented miniaturization of patterns, the existing merits of cost and efficiency cannot be lost.

The present inventor has a main pattern composed of a translucent portion, an auxiliary pattern composed of a phase shift portion for phase-shifting light of a predetermined wavelength arranged in the vicinity thereof, and a low translucent portion formed in other regions. (Patent Document 1) has been proposed. This photomask can be advantageously used when stably forming fine isolated holes on a transfer target such as a display panel substrate.

On the other hand, as the configuration of the display device becomes more complicated, the design of the transfer pattern also becomes complicated, and the present inventor has found a new problem that cannot be sufficiently solved even by using the photomask described in Patent Document 1. .. For example, when a plurality of hole patterns are arranged on a transfer body at a predetermined close distance to form a dense pattern, in the transfer pattern on the photomask, the auxiliary patterns of the respective main patterns are arranged with each other. approach. In this case, there is a risk that the transmitted light of the auxiliary pattern, which is not originally intended for transfer, causes the resist thickness to be lost on the transferred object and hinders the formation of the target transfer image.
Here, the dense pattern means a pattern in which two or more hole patterns are arranged close to each other on the transferred body, and therefore, two or more main patterns are arranged close to each other on a photomask. The pattern. The patterns arranged close to each other are patterns that are at a distance such that the hole-forming patterns on the photomask have an optical effect on each other in an exposure environment. In the present application, the patterns may be arranged close to each other, including the case where the main patterns are close to each other and the auxiliary patterns associated with the main patterns are close to each other.

Patent Document 2 describes a photomask that is exposed by a reduced projection exposure system using annulus illumination and used for manufacturing a semiconductor integrated circuit device. Among these, in a pattern having contour shifters surrounding the opening, when the distance between the contour shifters corresponding to each of the adjacent patterns becomes small, the contour shifters are combined to form one phase shifter. It is stated that. Specifically, for example, as shown in FIG. 15, there is a case where the openings patterns 721, 722, and 723 are surrounded by four contour shifters 711, 712, and 713, respectively, and the distance between the opening patterns 722 and the opening pattern 723. When is small, the contour shifter 714 is a contour shifter shared by both the aperture pattern 722 and the aperture pattern 723. The photomask described in Patent Document 2 is useful because the isolated space pattern and the isolated line pattern or the dense pattern can be miniaturized at the same time.

However, according to the study of the present inventor, it has been found that the method described in Patent Document 2 is not always useful in a photomask for manufacturing a display device.

Therefore, an object of the present invention is to provide a photomask for manufacturing a display device capable of stably forming a fine hole pattern on a transfer target when manufacturing a display device.

(First aspect)
The first aspect of the present invention is
A photomask for manufacturing display devices that has a transfer pattern on a transparent substrate.
The transfer pattern is
Main pattern consisting of quadrangular translucent parts,
Includes an auxiliary pattern consisting of a phase shift portion arranged around the main pattern, and a low light transmissive portion formed in a region other than the main pattern and the auxiliary pattern.
When defining a regular octagonal band of a predetermined width that surrounds the main pattern around the main pattern, the auxiliary pattern constitutes at least a part of the regular octagonal band.
When one of the plurality of main patterns included in the transfer pattern is used as the first main pattern, a second main pattern different from the first main pattern is arranged at a position close to the first main pattern.
Of the eight sections constituting the regular octagonal band surrounding the first main pattern, an auxiliary pattern having a gap in one section facing the second main pattern side is arranged around the first main pattern. It is a photomask for manufacturing a display device, which is characterized by the above.
(Second aspect)
A second aspect of the present invention is
When the diameter of the main pattern is W1, the transfer pattern is characterized in that a hole pattern having a diameter of W2 (however, W1 ≧ W2) is formed as a transfer image of the main pattern on the transferred object. The photomask for manufacturing a display device according to the first aspect.
(Third aspect)
A third aspect of the present invention is
When the arrangement direction of the first main pattern and the second main pattern is the X direction, the dimension of the first main pattern in the X direction is smaller than the dimension in the Y direction perpendicular to the X direction. , The photomask for manufacturing a display device according to the first or second aspect.
(Fourth aspect)
A fourth aspect of the present invention is
The transfer pattern includes a dense pattern in which three or more main patterns are regularly arranged in the X direction, the Y direction perpendicular to the X direction, or the X direction and the Y direction, and constitutes the dense pattern. One of the first to third aspects, wherein each of the main patterns to be used has the auxiliary pattern lacking at least one section facing the other main pattern side among the eight sections. The photomask for manufacturing the display device according to the above.
(Fifth aspect)
A fifth aspect of the present invention is
The phase shift portion is formed on the transparent substrate by forming a phase shift film having a transmittance of 20 to 80% with respect to a representative wavelength of the exposure light and shifting the phase of the exposure light by approximately 180 degrees. The photomask for manufacturing a display device according to any one of the first to fourth aspects described above.
(Sixth aspect)
A sixth aspect of the present invention is
The photomask for manufacturing a display device according to any one of the first to fifth aspects, wherein the low light-transmitting portion is a light-shielding portion having an optical density OD of 2 or more with respect to exposure light. is there.
(7th aspect)
A seventh aspect of the present invention is
The step of preparing the photomask according to any one of the first to sixth aspects, and
The transfer pattern is exposed by using an exposure device having an exposure light source having a numerical aperture (NA) of 0.08 to 0.15 and containing at least one of i-line, h-line, and g-line. This is a method for manufacturing a display device, which includes a step of forming a hole pattern having a diameter W2 of 0.8 to 3.0 (μm) on the transferred body.

According to the present invention, when a display device is manufactured, a fine hole pattern can be stably formed on a transfer target.

The main part of the transfer pattern of the photomask described in Patent Document 1 is shown, (a) is a schematic plan view, and (b) is a schematic cross-sectional view of the AA position in (a). (A) to (c) are plan views showing the patterns of the photomasks of Reference Examples 1 to 3. It is a figure which shows the simulation result of Reference Examples 1 to 3. It is a top view which shows the case where the main pattern of Reference Example 3 is arranged close to each other. (A) is a plan view illustrating the case where the first main pattern and the second main pattern are sufficiently separated from each other, and (b) illustrates the structure of the resist pattern formed on the transferred body in that case. It is a cross-sectional view. (A) is a plan view illustrating the case where the second main pattern is close to the first main pattern, and (b) illustrates the structure of the resist pattern formed on the transferred body in that case. It is a cross-sectional view. The main part of the transfer pattern included in the photomask for manufacturing a display device according to the embodiment of the present invention is illustrated, (a) is a schematic plan view, and (b) is a schematic cross-sectional view of the BB position in (a). It is a figure. It is a top view which shows the example which divided the auxiliary pattern arranged around the main pattern into eight sections. It is sectional drawing which illustrates the structure of the resist pattern formed on the transfer | transfer body when the transfer pattern of the photomask which concerns on embodiment of this invention is applied. (A) to (e) are plan views showing the patterns of the photomasks of Reference Examples 4 to 8. (F) to (i) are plan views showing the patterns of the photomasks of Examples 1 to 4. It is a figure which shows the reference example and the simulation result of the Example in the Embodiment of this invention. It is a top view which shows the example of the transfer pattern of the photomask including the main pattern which applied the mask bias β2. (A) to (f) are process diagrams illustrating an example of a method for producing a photomask applicable to the embodiment of the present invention. It is a top view which shows the pattern of the photomask described in Patent Document 2. FIG.

[Design of photomask for hole pattern formation with auxiliary pattern]
FIG. 1 shows a main part of a transfer pattern of a photomask described in Patent Document 1, in which (a) is a schematic plan view and (b) is a schematic cross-sectional view of positions AA in (a). is there.
The illustrated transfer pattern of the photomask has a main pattern 1 composed of a translucent portion and an auxiliary pattern 2 arranged around the main pattern 1 so as to surround the main pattern 1. The auxiliary pattern 2 is arranged around the main pattern 1 in association with the main pattern 1.

Further, a phase shift film 11 and a low translucency film 12 are formed on the transparent substrate 10. The main pattern 1 is composed of a translucent portion 4 in which the transparent substrate 10 is exposed, and the auxiliary pattern 2 is composed of a phase shift portion 5 in which the phase shift film 11 on the transparent substrate 10 is exposed. Further, the low translucency portion 3 surrounds the main pattern 1 and the auxiliary pattern 2, respectively.

The low translucency portion 3 is composed of a laminated film of a phase shift film 11 and a low translucency film 12 formed on a transparent substrate 10. The low light-transmitting portion 3 can also be formed of a single-layer film of the low light-transmitting film 12 formed on the transparent substrate 10. That is, the low translucency portion 3 is composed of at least a portion on which the low translucency film 12 is formed. In the illustrated transfer pattern, the region other than the region where the main pattern 1 and the auxiliary pattern 2 are formed is the low translucency portion 3.

The phase shift film 11 has a phase shift amount that shifts the exposure light of a representative wavelength in the wavelength range of i-line to g-line by approximately 180 degrees. That is, the auxiliary pattern has an action of inverting the phase of the transmitted light by the phase shift film 11. Further, the phase shift film 11 has a transmittance of T1 (%) with respect to the exposure light having the above representative wavelength.

According to Patent Document 1, when an optical simulation of forming a hole pattern on an object to be transferred was performed using a photomask provided with the above transfer pattern, it was compared with a binary mask and a phase shift mask having no auxiliary pattern. As a result, it has been clarified that excellent performance is exhibited in Eop (the amount of exposure light required to form a pattern of target dimensions on the transferred object), DOF (depth of focus), and the like.

The present inventor performed an optical simulation of the photomasks shown in FIGS. 2 (a) to 2 (c) in order to form a finer pattern on the transferred object. Here, the photomask of FIG. 2A is referred to as Reference Example 1, the photomask shown in FIG. 2B is referred to as Reference Example 2, and the photomask shown in FIG. 2C is referred to as Reference Example 3. Then, using each of the photomasks of Reference Examples 1 to 3 having a main pattern consisting of a hole pattern having a diameter W1 of 2.0 μm, a positive photoresist on a transfer object (display panel substrate or the like) has a diameter W2. A simulation was performed to form a transfer image corresponding to a hole pattern (1.5 μm in this case).
As described above, the diameter W1 on the photomask is W1 ≧ W2 (preferably W1> W2) with respect to the target diameter W2 on the transferred object. Here, the mask bias β1 (μm) is set to β1 = W1-W2.
Then, here, β1 is set to 0.5 (μm).

The conditions of the simulation are as follows.
(Reference example 1)
In Reference Example 1, as shown in FIG. 2A, a photomask made of a binary mask is used, and a square translucent portion having a diameter W1 = 2 μm surrounded by a low translucent portion (light-shielding portion) 3 is used. The hole pattern is the main pattern 1.
(Reference example 2)
In Reference Example 2, as shown in FIG. 2B, a photomask composed of a halftone type phase shift mask is used, and the phase shift unit 5 having an exposure light transmittance of 5.2% and a phase shift amount of 180 ° is used. The hole pattern composed of a square translucent portion having a diameter of W1 = 2 μm surrounded by is defined as the main pattern 1.
(Reference example 3)
In Reference Example 3, as shown in FIG. 2C, a photomask composed of a phase shift mask with an auxiliary pattern is used, and a hole pattern composed of a square translucent portion having a diameter W1 = 2 μm is set as the main pattern 1. Auxiliary pattern 2 of a regular octagonal band surrounds the periphery. Further, the auxiliary pattern 2 is composed of a phase shift portion having a transmittance of exposure light of 45% and a phase shift amount of 180 degrees, and the regions other than the main pattern 1 and the auxiliary pattern 2 have a low optical density of OD ≧ 2. It was composed of a translucent portion (light-shielding portion) 3. The distance (L) between the center of the main pattern 1 and the center position in the width direction of the auxiliary pattern 2 was 3.25 μm, and the width (d) of the auxiliary pattern 2 was 1.3 μm. The photomask of Reference Example 3 is designed based on the configuration described in Patent Document 1.

It was decided to form a hole pattern having a width of W2 = 1.5 μm on the transferred object using each photomask corresponding to Reference Examples 1 to 3.
The exposure conditions of the simulation are as follows.
The optical system of the exposure apparatus has a numerical aperture NA of 0.1 and a coherent factor σ of 0.5. Further, as the exposure light source, a light source (broad wavelength light source) including all of i-line, h-line, and g-line was used, and the intensity ratio was set to g: h: i = 1: 1: 1.

The optical evaluation items of the photomask are as follows.
(1) Depth of focus (DOF)
The magnitude of the depth of focus for the CD fluctuation with respect to the target CD to be within a predetermined range (for example, ± 10%) on the transferred object when defocus occurs during exposure. When the value of DOF is high, it is not easily affected by the flatness of the transferred body (for example, a panel substrate for a display device), a fine pattern can be reliably formed, and the CD variation can be suppressed. In the simulation of the present application, the target CD ± 10% is used as the reference as the DOF value. Here, CD is an abbreviation for Critical Dimension, and is used in the sense of pattern width. Photomasks for manufacturing display devices are larger in size than photomasks for manufacturing semiconductor devices, and transfer objects (display panel substrates, etc.) are also larger in size, and all have perfect flatness. Therefore, it is very significant to use a photomask that can increase the value of DOF.
(2) Mask error increase coefficient (MEEF: Mask Error Enhancement Factor)
It is a numerical value indicating the ratio of the CD error of the pattern formed on the transferred body to the CD error on the photomask, and the lower the MEEF, the more the CD error of the pattern formed on the transferred body can be reduced. As the specifications of display devices have evolved, miniaturization of patterns has been required, and photomasks with dimensions close to the resolution limit of exposure devices have become necessary. Therefore, photomasks for manufacturing display devices are also required. There is a high possibility that MEEF will be emphasized in the future.
(3) Eop
A particularly important evaluation item in a photomask for manufacturing a display device is Eop (hereinafter, also referred to as "Eop Dose"). Eop is the amount of exposure light required to form the pattern size to be obtained on the transfer target. Photomasks used in the manufacture of display devices are very large in size (eg, squares or rectangles with one side of the main surface of about 300-2000). Therefore, if a photomask having a low Eop value is used, the speed of scan exposure can be increased and the production efficiency is improved.

FIG. 3 shows specific evaluation results for the above evaluation items.
First, focusing on Eop, the photomask of Reference Example 3 has a smaller exposure amount (Eop value) of 30% or more for obtaining a hole pattern of target dimensions than the photomasks of Reference Example 1 and Reference Example 2. It has become. Therefore, it can be seen that high production efficiency can be obtained by using the photomask of Reference Example 3. Further, the photomask of Reference Example 3 has a higher DOF value and a lower MEEF value than the photomasks of Reference Example 1 and Reference Example 2. Therefore, it can be seen that the photomask of Reference Example 3 is also very advantageous in DOF and MEEF.

[Design of hole patterns located close to each other]
On the other hand, as the resolution required for the display device increases, the degree of integration increases due to the increase in the number of pixels per unit area. Therefore, as a transfer pattern of a photomask for manufacturing a display device, it is necessary to arrange a plurality of main patterns (hole patterns) in close proximity to each other. Hereinafter, the case where the photomask of Reference Example 3 is applied to the formation of a dense pattern including a plurality of main patterns will be examined.

FIG. 4 shows a case where the patterns applied to the reference example 3 (the main pattern and the auxiliary patterns formed around the main pattern are combined and also referred to as a hole forming pattern in the present application) are arranged close to each other. Here, one of the two main patterns is referred to as the first main pattern 1a, and the other is referred to as the second main pattern 1b. Then, when the position of the second main pattern 1b is brought closer to the first main pattern 1a from the direction of the arrow, the hole pitch P, which is the distance between the centers of gravity of the two main patterns 1a and 1b, and the hole pitch P formed on the transferred body. Consider the cross-sectional shape of the resist pattern.

First, as shown in FIG. 5 (a), when the first main pattern 1a and the second main pattern 1b are sufficiently separated (P = 12 μm), the transfer is performed as shown in FIG. 5 (b). Hole patterns 21a and 21b corresponding to the respective main patterns 1a and 1b are formed in the resist pattern (here, a pattern composed of a positive photoresist) 20 on the body.

On the other hand, as shown in FIG. 6A, when the second main pattern 1b approaches the first main pattern 1a (P = 8 μm), the auxiliary is arranged around the respective main patterns 1a and 1b. The distance between the patterns 2a and 2b becomes extremely close. At this time, looking at the cross section of the resist pattern 20 formed on the transferred body, as shown in FIG. 3B, in addition to the hole patterns 21a and 21b corresponding to the main patterns 1a and 1b, an intermediate between them. A recess 22 is formed in the portion, and a large loss of resist film thickness occurs there. Such a local reduction of the resist residual film may adversely affect the processing stability of the display device substrate in which the resist pattern is used as an etching mask.

Therefore, the present inventor solves this inconvenience with respect to the hole-forming pattern of Reference Example 3 in which the above-mentioned local reduction of the resist residual film, which has advantageous characteristics in Eop and DOF, occurs. A photomask that can be examined.

<Composition of photomask>
Next, the configuration of the photomask for manufacturing the display device according to the embodiment of the present invention will be described.
The photomask for manufacturing a display device according to the embodiment of the present invention is
A photomask for manufacturing display devices that has a transfer pattern on a transparent substrate.
The transfer pattern is
Main pattern consisting of quadrangular translucent parts,
Includes an auxiliary pattern consisting of a phase shift portion arranged around the main pattern, and a low light transmissive portion formed in a region other than the main pattern and the auxiliary pattern.
When defining a regular octagonal band of a predetermined width that surrounds the main pattern around the main pattern, the auxiliary pattern constitutes at least a part of the regular octagonal band.
When one of the plurality of main patterns included in the transfer pattern is used as the first main pattern, a second main pattern different from the first main pattern is arranged at a position close to the first main pattern.
Of the eight sections constituting the regular octagonal band surrounding the first main pattern, an auxiliary pattern having a gap in one section facing the second main pattern side is arranged around the first main pattern.
Hereinafter, a specific description will be given with reference to FIG. 7.

7A and 7B show a main part of a transfer pattern included in a photomask for manufacturing a display device according to an embodiment of the present invention, in which FIG. 7A is a schematic plan view and FIG. 7B is a position BB in FIG. 7A. It is a cross-sectional schematic diagram of.

The photomask for manufacturing a display device (hereinafter, also simply referred to as “photomask”) is formed by, for example, patterning a phase shift film 11 and a low light transmissive film 12 formed on a transparent substrate 10. It is equipped with a transfer pattern. This transfer pattern includes a main pattern 1 (1a, 1b) and an auxiliary pattern 2 (2a, 2b) arranged around the main pattern 1. The auxiliary pattern 2 has a shape that constitutes at least a part of a regular octagonal band having a predetermined width that surrounds the main pattern 1.

Two main patterns 1 are arranged in the X direction, one of which is the first main pattern 1a and the other of which is the second main pattern 1b. An auxiliary pattern 2a is arranged around the first main pattern 1a, and an auxiliary pattern 2b is arranged around the second main pattern 1b. In FIG. 7A, the main pattern on the left side is the first main pattern and the main pattern on the right side is the second main pattern, but either of them may be the first main pattern.

In the present embodiment, the main pattern 1 is composed of a translucent portion 4 in which the transparent substrate 10 is exposed, and the auxiliary pattern 2 is composed of a phase shift portion 5 in which the phase shift film 11 on the transparent substrate 10 is exposed. Further, the region other than the main pattern 1 and the auxiliary pattern 2 is a low translucency portion 3 in which at least a low translucency film 12 is formed on the transparent substrate 10.

In the present embodiment, the low translucency portion 3 is formed by laminating a phase shift film 11 and a low translucency film 12 on a transparent substrate 10. The phase shift film 11 has a phase shift amount that shifts the exposure light of a representative wavelength in the wavelength range of i-line to g-line by approximately 180 degrees. Further, the transmittance of the phase shift film 11 with respect to the exposure light of the representative wavelength is T1 (%).

The low transmissive film 12 can have a predetermined low transmittance with respect to the representative wavelength of the exposure light. In the present embodiment, the low transmissive film 12 has a transmittance T2 (%) lower than the transmittance T1 (%) of the phase shift film 11 with respect to the exposure light having a representative wavelength in the wavelength range of i-line to g-line. Can have. Alternatively, the low light-transmitting film 12 may be a light-shielding film that does not substantially transmit the exposure light.

Here, when a fine pattern (hole pattern) corresponding to the main pattern 1 of the photomask is formed on the transferred body by exposure using a photomask, if the diameter W1 of the main pattern 1 is 4 μm or less, the subject is covered. A fine pattern having a diameter of W2 (μm) (where W1 ≧ W2, more preferably W1> W2) can be formed on the transfer body.

Specifically, the diameter W1 (μm) of the main pattern 1 is preferably 0.8 ≦ W1 ≦ 4.0, and more preferably 1.0 ≦ W1 <3.5.
Further, 1.2 <W1 ≦ 3.0 can be set, and 1.2 <W1 <2.5 can be set when further miniaturization is required.

The diameter W2 (μm) of the hole pattern formed on the transferred body as the transfer image of the main pattern 1 is preferably 0.8 ≦ W2 ≦ 3.0, more preferably 0.8 ≦. W2 ≦ 2.5, more preferably 0.8 ≦ W2 ≦ 2.0, or 0.8 ≦ W2 ≦ 1.8.
Alternatively, 0.8 <W2 <2.0 or 0.8 <W2 <1.8 can be set. When further miniaturization is required, 0.8 <W2 <1.5 can be set.

Further, the photomask according to the present embodiment can be used for the purpose of forming a fine-sized pattern useful for manufacturing a display device. For example, when the diameter W1 of the main pattern 1 is 3.0 (μm) or less, a more remarkable effect can be obtained.

By the way, in a photomask for forming a hole pattern on a transferred body (for example, Reference Examples 1 to 3 above), it is advantageous to apply mask bias β1 as described above. That is, assuming that the diameter of the hole pattern on the photomask is W1 and the diameter of the hole pattern formed on the transfer target is W2, W1 = W2 can be set, but W1> W2 is preferable. For example, assuming that β1 (μm) is the bias value (W1-W2) and β1> 0 (μm), the bias value β1 (μm) is preferably 0.2 ≦ β1 ≦ 1.0. Preferably, 0.2 ≦ β1 ≦ 0.8.
By defining the relationship between the diameter W1 and the diameter W2 as the bias value β1 in this way, an advantageous effect such as reduction of the loss of the film thickness of the resist pattern on the transferred object can be obtained.

The main pattern 1 is composed of a quadrangular pattern, and the diameter W1 of the main pattern 1 is the dimension of one side of the quadrangle. For example, if the main pattern 1 is a square pattern, the diameter W1 of the main pattern 1 means the dimension of one side, and if it is a rectangular pattern, it means the dimension of the long side. The shape of the main pattern 1 refers to the shape when the main pattern 1 is viewed in a plane. Further, the diameter W2 of the hole pattern formed on the transferred body refers to the length of the largest portion of the distance between the two opposing sides.

Such mask bias β1 can also be applied to the photomask according to the present embodiment. In the present embodiment, due to the fact that the two hole forming patterns are formed close to a predetermined distance, the size given as the mask bias β1 is larger than that of the isolated pattern (reference examples 1 to 3 above). , May grow.

Further, the photomask according to the present embodiment has uneven dimensions with respect to the X direction and the Y direction perpendicular to the X direction, depending on the positional relationship between the two hole forming patterns arranged close to each other. It may be preferable to apply a mask bias. Therefore, the mask bias β2 is used, and the bias amounts applied to the X direction and the Y direction perpendicular to the mask bias β2 are β2 (x) and β2 (y), respectively. The details of the mask bias β2 will be described later.

The phase difference φ between the main pattern 1 and the auxiliary pattern 2 is approximately 180 degrees with respect to the representative wavelength of the exposure light used for the exposure of the photomask of the present embodiment having the above transfer pattern. That is, the phase difference φ1 between the light having the representative wavelength transmitted through the main pattern 1 and the light having the representative wavelength transmitted through the auxiliary pattern 2 is approximately 180 degrees. Approximately 180 degrees means 120 to 240 degrees. The phase difference φ1 is preferably 150 to 210 degrees.

The photomask of the present embodiment has a remarkable effect when an exposure light containing at least one of i-line, h-line, and g-line is used, and particularly, a broad including i-line, h-line, and g-line. It is preferable to apply wavelength light as exposure light. In this case, any wavelength in the wavelength range of i-line to g-line can be used as the representative wavelength. For example, the photomask of the present embodiment can be constructed using h-line as a representative wavelength. More preferably, the phase difference φ1 with respect to the representative wavelength is φ1 = 180 degrees.

In the photomask of the present embodiment, in order to realize the above phase difference, the main pattern 1 is a translucent portion 4 in which the main surface of the transparent substrate 10 is exposed, and the auxiliary pattern 2 is on the transparent substrate 10. The phase shift film 11 formed in the above is used as the phase shift portion 5 formed by exposing the phase shift film 11, and the phase shift amount of the phase shift film 11 with respect to the representative wavelength may be set to about 180 degrees.

The light transmittance T1 of the phase shift unit 5 can be set as follows. That is, assuming that the transmittance of the phase shift film 11 formed in the phase shift portion 5 with respect to the representative wavelength is T1 (%), it is preferably 20 ≦ T1 ≦ 80, and more preferably 30 ≦ T1 ≦ 75. More preferably, 40 ≦ T1 ≦ 75. If the transmittance of the auxiliary pattern 2 is high, the auxiliary pattern width (d) can be reduced in order to obtain a predetermined amount of transmitted light. Therefore, there is an advantage that the degree of freedom that can be arranged while avoiding physical interference with each other in the dense pattern can be obtained. On the other hand, if the transmittance T1 is slightly lowered and the auxiliary pattern width (d) is widened, there is an advantage that the difficulty in manufacturing the pattern formation is alleviated. In that case, 40 to 60 (%) is preferable.
The transmittance T1 (%) here is the transmittance of the representative wavelength when the transmittance of the transparent substrate 10 is used as a reference (100%).

In the photomask of the present embodiment, the low translucency portion 3 is formed in a region other than the region in which the main pattern 1 and the auxiliary pattern 2 are formed. Here, the main pattern 1 and the auxiliary pattern 2 are separated from each other via the low translucency portion 3. The low light transmissive portion 3 can have the following configuration.

The low transmissive portion 3 is a low transmissive film (that is, a light shielding film) 12 that does not substantially transmit exposure light (light having a representative wavelength in the wavelength range of i-line to g-line), and has an optical density of OD ≧ 2. A film (preferably OD ≧ 3) can be formed on the transparent substrate 10.

Further, the low translucency portion 3 may be formed by forming a low translucency film 12 that transmits exposure light with a transmittance in a predetermined range. However, when the exposure light is transmitted with a transmittance within a predetermined range, the transmittance T3 (%) of the low light transmittance unit 3 with respect to the representative wavelength is higher than the transmittance T1 (%) of the phase shift unit 5. It is assumed that 0 <T3 <T1 is satisfied, and preferably 0 <T3 ≦ 20 is satisfied. Here, when the phase shift portion 5 is composed of a laminated film of the phase shift film 11 and the low translucency film 12 instead of the single layer film of the phase shift film 11, the transmittance of the laminated film is T3 ( %). Similarly, the transmittance T3 (%) here is also the transmittance of the representative wavelength when the transmittance of the transparent substrate 10 is used as a reference.

Further, when the low translucent film 12 transmits the exposure light with a transmittance within a predetermined range, the phase shift amount φ3 in the laminated state of the phase shift film 11 and the low transmissive film 12 is preferably set. , 90 (degrees) or less, more preferably 60 (degrees) or less. "90 degrees or less" means that the phase difference is "(2n-1 / 2) π to (2n + 1/2) π (where n is an integer)" in radian notation. The phase difference is also the same as the above with respect to the representative wavelength included in the exposure light.

Further, as a single property of the low translucency film 12 used in the photomask of the present embodiment, is it substantially non-transmitting light of the above representative wavelength (OD ≧ 2, more preferably OD> 3)? Alternatively, it is preferable that the transmittance (T2 (%)) is less than 30 (%) (that is, 0 <T2 <30) and the phase shift amount (φ2) is approximately 180 degrees. Approximately 180 degrees means 120 to 240 degrees. Preferably, the phase shift amount φ2 is 150 to 210 degrees.

Similarly, the transmittance T2 (%) here is also the transmittance of the representative wavelength when the transmittance of the transparent substrate 10 is used as a reference.

In the transfer pattern according to the present embodiment, assuming that the width of the auxiliary pattern 2 is d (μm), a remarkable effect can be obtained when the relationship of the following formula (1) is established.
0.5 ≤ √ (T1 / 100) x d ≤ 1.5 ... (1)
At this time, assuming that the distance between the center of the main pattern 1 and the center of the auxiliary pattern 2 in the width direction is the slit pitch 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 part of the region of the regular octagonal band surrounding the main pattern 1 via the low translucency portion 3. Therefore, the slit pitch L is provided so that the main pattern 1 and the auxiliary pattern 2 do not come into contact with each other, that is, the low translucency portion 3 is interposed between the main pattern 1 and the auxiliary pattern 2. And the main pattern diameter W1 can be determined.

The width d (μm) of the auxiliary pattern 2 is set so that the auxiliary pattern having the light transmittance T1 is not resolved under the exposure conditions (exposure apparatus used) applied to the photomask of the present embodiment.
To give a specific example, the width d (μm) of the auxiliary pattern 2 is preferably d ≧ 0.7, and more preferably d ≧ 0.8. Further, as compared with the width W1 (μm) of the main pattern 1, d ≦ W1 is preferable, and d <W1 is more preferable.

Further, regarding the width d (μm) of the auxiliary pattern 2, the relational expression represented by the above equation (1) is more preferably the following equation (1) -1, and further preferably the following equation (1)-. It is 2.
0.7 ≦ √ (T1 / 100) × d ≦ 1.2 ・ ・ ・ (1) -1
0.75 ≦ √ (T1 / 100) × d ≦ 1.0 ・ ・ ・ (2) -2

The shape of the main pattern 1 included in the transfer pattern of the present embodiment is a quadrangle. Specifically, for example, it is preferably square or rectangular. When the shape of the main pattern 1 is a quadrangle, the distance between the position of the center of gravity of the quadrangle and the center of the auxiliary pattern 2 in the width direction is the slit pitch L.

In the present embodiment, when a regular octagonal band having a predetermined width surrounding the main pattern 1 is defined around the main pattern 1, the auxiliary pattern 2 is a pattern that constitutes at least a part of the regular octagonal band. A regular octagonal band is a shape in which both the outer circumference and the inner circumference are octagonal and have a substantially constant width. As shown in FIG. 7, the auxiliary pattern has a constant width except for the corners.
The regular octagonal band in which the auxiliary pattern 2 is defined is arranged so as to surround the main pattern 1. The center of gravity of the regular octagon, which is the inner and outer shells of the regular octagonal band of the auxiliary pattern, is at the same position as the center of gravity of the main pattern. In the present embodiment, for convenience of explanation, as shown in FIG. 8, the above-mentioned regular octagonal band is divided into eight sections corresponding to each side of the octagon on the outer circumference (or inner circumference). Here, among the eight sections, the rightmost section in FIG. 8 is referred to as section A, the upper section adjacent thereto is referred to as section H, and the lower section is referred to as section B. That is, the compartments B, C, D, E, F, G, and H are set in the clockwise order from the compartment A.

As shown in FIG. 4, when the second main pattern 1b is arranged at a position closer to the first main pattern 1a, in the present embodiment, the regular octagonal band is formed around the first main pattern 1a. Auxiliary pattern 2a having a defect is arranged in one of the eight constituent sections A to H facing the second main pattern 1b side. Specifically, as shown in FIG. 7A, an auxiliary pattern 2a in which a part of the octagonal band is missing is arranged around the first auxiliary pattern 1a. As shown in the figure, the auxiliary pattern 2a attached to the first main pattern 1a has a shape having a gap on the side facing the second main pattern 1b, that is, the rightmost section (corresponding to the above section A). Further, the auxiliary pattern 2b accompanying the second main pattern 1b also has a shape in which one section facing the first main pattern 1a side (corresponding to the above section E) has a defect. That is, the two main patterns 1a and 1b each have an octagonal band-shaped auxiliary pattern having a gap in one section on the side facing each other.
That is, when the two hole forming patterns are arranged at an approach distance of a predetermined distance or less, the auxiliary patterns 2a and 2b included in the main patterns 1a and 1b are missing between the two main patterns 1a and 1b. doing. Therefore, when the centers of gravity of the two main patterns 1a and 1b are connected by a straight line (not shown), this straight line does not cross the auxiliary patterns 2a and 2b at all.
It is preferable that the auxiliary pattern is not substantially arranged in the region S (shown by the dotted line in FIG. 7) sandwiched between the two main patterns 1a and 1b facing each other. However, when a part of the auxiliary pattern is included in the region S, it is preferable that the portion does not have a side parallel to the side facing each other of the two main patterns 1a and 1b. In the embodiment shown in FIG. 7, the ends of the auxiliary patterns 2a and 2b are included in the region S, and the ends are inclined with respect to the sides of the two main patterns 1a and 1b facing each other. I only have.
Further, it is preferable that there is no island-shaped (shape surrounded by a closed straight line or curve) auxiliary pattern in the region S.
Further, it is preferable that 90% or more of the area in the region S is composed of the low translucency portion 3. By doing so, the resist pattern shape of the two hole patterns formed on the transferred body is improved, and the loss of the resist residual film thickness can be suppressed.

When the auxiliary patterns 2a and 2b in which some of the sections are missing are arranged in this way, the loss of resist film thickness due to the recess 22 shown in FIG. 6B is eliminated as shown in FIG. 9, and a good profile is obtained. It became a resist pattern shape with. Note that both FIG. 6B and FIG. 9 show a case where the hole pitch P is 8 μm.

The permissible range of the loss of the resist film thickness seen in FIG. 6B can be determined by the manufacturing conditions of the display device to be obtained by using the photomask. Assuming that the initial film thickness (coating film thickness) of the resist film is 100%, it can be said that it is a good condition that the allowable range of the loss is 10% or less, more preferably 5% or less of the initial film thickness.

Therefore, in the present embodiment, whether or not the auxiliary patterns 2a and 2b associated with the main patterns 1a and 1b that are close to each other are partially omitted is determined by grasping the loss amount of the resist film thickness in advance by an experiment or a simulation. Judgment should be made based on the result. Specifically, when the loss amount of the resist film thickness exceeds, for example, 10%, the auxiliary patterns 2a and 2b are partially omitted, and when the loss amount is 10% or less, the auxiliary patterns 2a and 2b are not omitted. Is useful.

Further, when the second main pattern 1b is arranged at a position closer to the first main pattern 1a and the distance D (see FIG. 4) between the auxiliary patterns 2a and 2b is 1.0 μm or less, the first It is desirable to omit the section (section A mentioned above) of the auxiliary pattern 2a arranged around the first main pattern 1a and facing the second main pattern 1b side. Similarly, also in the second main pattern 1b, it is preferable to form the auxiliary pattern 2b in which the section facing the first main pattern 1a side (the section E mentioned above) is omitted. Further, it is more preferable to apply the lack of the partition when the distance D between the auxiliary patterns 2a and 2b is 1.5 μm or less.
The above is an example in view of the resolution performance of the exposure device for a display device.

As shown in FIG. 4, the distance between the auxiliary patterns means the distance between the opposing sections (the length of the perpendicular line). Therefore, as shown in the figure, when two main patterns 1a and 1b are arranged next to each other in a certain direction and each main pattern 1a and 1b are surrounded by auxiliary patterns 2a and 2b corresponding to (accompanying) each of them. In the arrangement direction of the two main patterns 1a and 1b, the distance between the opposing (facing) sides of the auxiliary patterns 2a and 2b is the distance D between the auxiliary patterns.

Further, the photomask of the present embodiment can obtain the remarkable effect of the present invention when the hole pitch P, which is the distance between the centers of gravity of the main patterns 1a and 1b, is 1.6 μm or more, preferably 3 μm or more. If the value of P is too small, the amount of residual film of the resist pattern formed at the corresponding position between the two main patterns may not be sufficiently obtained, or the value of β2 described later becomes too large and the pattern design. There is a risk of inconvenience such as difficulty.

An optical simulation according to an embodiment and a reference example of the present invention will be described below.
FIG. 10 is a schematic plan view showing a main part of the transfer pattern included in the photomask of the reference example, in which (a) is Reference Example 4, (b) is Reference Example 5, and (c) is Reference Example 6. (D) shows Reference Example 7 and (e) shows Reference Example 8. FIG. 11 is a schematic plan view showing a main part of the transfer pattern included in the photomask of the embodiment, in which (f) is Example 1, (g) is Example 2, and (h) is Example 3. (I) shows Example 4.

Further, FIG. 10A shows a case where the hole pitch P (see FIGS. 5 to 7) of the main patterns 1a and 1b is 16 μm and the auxiliary patterns 2a and 2b of the regular octagonal band have no sections. FIG. 10B shows a case where the hole pitch P of the main patterns 1a and 1b is 12 μm and the auxiliary patterns 2a and 2b have no sections missing.
Further, FIG. 10C shows a case where the hole pitch P of the main patterns 1a and 1b is 9 μm and the auxiliary patterns 2a and 2b have no sections, and FIG. 10D shows the case where the main patterns 1a and 1b have no gaps. The case where the hole pitch P is 8.75 μm and the auxiliary patterns 2a and 2b have no sections is shown.
FIG. 10E shows a case where the hole pitch P of the two main patterns 1a and 1b is 8.75 μm, and one section of each of the auxiliary patterns 2a and 2b is connected and shared.

On the other hand, FIG. 11 (f) shows a case where the hole pitch P of the main patterns 1a and 1b is 8.75 μm and the auxiliary patterns 2a and 2b are omitted by one section, and FIG. 11 (g) shows the case where the main patterns 1a and 1b are omitted. The case where the hole pitch P of 1b is 8 μm and the auxiliary patterns 2a and 2b are omitted by one section is shown. Further, FIG. 11 (h) shows a case where the hole pitch P of the main patterns 1a and 1b is 7.5 μm and the auxiliary patterns 2a and 2b are omitted by one section, and FIG. 11 (i) shows the case where the main patterns 1a and 1b are omitted. The case where the hole pitch P of 1b is 7 μm and the auxiliary patterns 2a and 2b are omitted by 3 sections is shown.

Further, in this simulation, the case where the photomask (binary mask) shown in FIG. 2A is used is used as Reference Example 1, and the photomask (halftone type phase shift mask) shown in FIG. 2B is used. In reference example 2, the case of The main patterns applied to Reference Example 1 and Reference Example 2 are both isolated patterns without auxiliary patterns.

When an optical simulation was performed on each of the above photomask patterns, the results shown in FIG. 12 were obtained. In this simulation, except for Reference Example 1 and Reference Example 2, the Dose of 80 mJ / cm ² , which is the exposure energy used for the transfer of the main pattern (isolated pattern) shown in FIG. 2 (c), is used as a reference. Was applied, and the resist pattern formed on the transferred material was evaluated. In addition, "panel X-CD" and "panel Y-CD" are dimensions in the X direction and the Y direction of the hole pattern formed on the transferred body corresponding to the main pattern of the photomask. In each reference example and each embodiment, the target dimensions of X-CD and Y-CD were set to 1.5 μm.

First, in Reference Example 4 of FIG. 10A, since the two main patterns 1a and 1b are sufficiently separated from each other, the respective main patterns 1a and 1b substantially exhibit optical performance as an isolated pattern. .. This point is the same in Reference Example 5 of FIG. 10 (b) and Reference Example 6 of FIG. 10 (c). On the other hand, as shown in Reference Example 7 of FIG. 10D, when the two main patterns 1a and 1b approach each other and the hole pitch P becomes as narrow as 8.75 μm, the distance D between the auxiliary patterns 2a and 2b is 0.95 μm. become. At this time, the loss of the resist film thickness exceeds 12%.

Here, as in Reference Example 8 of FIG. 10 (e), even when the auxiliary patterns 2a and 2b of the main patterns 1a and 1b that are close to each other are partially bonded to form a single piece and shared, the resist film is formed. The thickness loss is close to 12% and there is not much improvement.

According to the study of the present inventor, this problem is considered to be related to the photoresist applied to the manufacture of display devices. Specifically, the resist (positive photoresist) used in the manufacture of display devices is designed to have high sensitivity, unlike that for manufacturing semiconductor devices. Therefore, even with a relatively low amount of Dose, a corresponding film thickness reduction is unavoidable, and a local film thickness loss is likely to occur in an unintended portion.

The interaction between the main pattern 1 and the auxiliary pattern 2 that occurred in the photomask of Reference Example 3 is that the optical image formed by the light of the inverted phase transmitted through the auxiliary pattern 2 is the light intensity due to the transmitted light of the main pattern 1. It uses the phenomenon of increasing the peak. Then, the excellent transfer performance (DOF, MEEF) shown in FIG. 3 was obtained. On the other hand, the light intensity due to the light transmitted through the auxiliary pattern 2 also increases slightly due to the interaction with the main pattern 1. Since the photoresist used for manufacturing the display device has high sensitivity, the transmitted light of the auxiliary pattern 2 is transmitted when the auxiliary patterns 2 are close to each other or when the auxiliary patterns 2 are shared by a plurality of main patterns 1. It is considered that there is a risk of reducing the resist thickness on the transferred body.

On the other hand, in the first embodiment of FIG. 11F, one of the eight sections forming the regular octagonal band surrounding the first main pattern 1a is omitted, and the remaining seven sections face the second main pattern 1b side. An auxiliary pattern 2a having a section is arranged around the first main pattern 1a. That is, among the regular octagonal bands surrounding the periphery of the first main pattern 1a, the shape of the auxiliary pattern 2a is the closest to the regular octagonal band surrounding the periphery of the second main pattern 1b, and the compartments facing each other are omitted. Similarly, with respect to the second main pattern 1b, one section facing the first main pattern 1a side is omitted, and an auxiliary pattern 2b having the remaining seven sections is arranged around the second main pattern 1b.

In addition, in order to cut out the section of the auxiliary pattern, it is not always necessary to cut out according to the boundary line of the section shown in FIG. 8, for example, as shown in FIG. 7A, at least the main part of the section is missing. Just do it. The area of the missing portion should be 80% or more of the area of the number of sections to be missing, for example, 80% or more of the area of one section when one of the eight sections is missing. Is preferable. At this time, a portion where only the low light transmissive portion 3 is interposed is generated between the two main patterns, and the straight line connecting the centers of gravity of both main patterns 1a and 1b does not cross the auxiliary patterns 2a and 2b.

In this way, when the compartments facing each other are omitted from the auxiliary patterns of the two main patterns that approach each other, the loss of the resist film thickness becomes zero in the formed resist pattern, and the loss is greatly reduced. It can be seen that a remarkable effect can be obtained. Further, the same effect as this is obtained when both main patterns 1a and 1b are brought closer to each other as in the second embodiment of FIG. 11 (g) and the third embodiment of FIG. 11 (h) (hole pitch P =). It can be seen that it can also be obtained (in the case of 8 μm and P = 7.5 μm). The cross-sectional structure of the resist pattern in that case is the same as in FIG.

By the way, in the aspects of FIGS. 11 (f) to 11 (i), the diameter of the hole pattern transferred to the resist film is the initial target, even though the same exposure Dose as in Reference Examples 4 to 8 is applied. It is slightly smaller than the size. Specifically, with respect to the initial target size of 1.5 (μm), in Example 1, the X-CD (diameter in the X direction) is 1.39 (μm) and the Y-CD (Y direction). Diameter) is 1.37 (μm).
Therefore, in order to bring both X-CD and Y-CD on the transferred object closer to the target size (1.5 μm), it is desirable to make β1 larger than 0.5 μm.
Further, in order to make the X-CD and the Y-CD on the transferred object equally target dimensions (1.5 μm), it is preferable to apply appropriate mask bias β2 in the X direction and the Y direction, respectively.

Therefore, as shown in FIG. 12, in the embodiments (f) to (h) of FIG. 11, the CD on the mask is imparted with appropriate β2 (x) and β2 (y) to be transferred. Both X-CD and Y-CD have obtained the target size of 1.5 μm on the body.

As a result, in the case of the photomask of Example 1 of FIGS. 11 (f) to 11 (h), the numerical value (24) of DOF (depth of focus) is the binary mask of Reference Example 1 (FIG. 2 (a)). Further, it can be seen that the hole pattern having a desired diameter can be stably formed on the transferred object, which is larger than the halftone type phase shift mask (FIG. 2B) of Reference Example 2. Further, since the Eop Dose required for exposure is smaller than that of the binary mask of Reference Example 1 and the halftone type phase shift mask of Reference Example 2, the exposure process can be performed efficiently.

In addition, in the aspect of FIGS. 11 (f) to 11 (h), of the eight sections of the auxiliary pattern 2a attached to the first main pattern 1a and the eight sections of the auxiliary pattern 2b attached to the second main pattern 1b, each other. One section facing is missing. That is, the number of compartments of the auxiliary pattern 2 is 7 for each main pattern 1. On the other hand, when the two main patterns 1a and 1b are arranged closer to each other, the compartments located on both sides of the already missing compartment may be further omitted. For example, in the fourth embodiment of FIG. 11 (i), of the eight compartments of the auxiliary pattern 2a accompanying the first main pattern 1a, the compartment A and the compartments B and H located on both sides thereof are omitted, and the first 2 Of the eight compartments of the auxiliary pattern 2b attached to the main pattern 1b, the compartment E and the compartments D and F located on both sides thereof are omitted, so that the loss of the resist film thickness is set to zero. As a result, here, the number of compartments of the auxiliary pattern 2 is set to 5 by omitting three compartments for one main pattern 1.

Further, the number of main patterns 1 arranged close to each other is not limited to 2, and a larger number of hole forming patterns can be arranged at close distances, and even in this case, the divisions may be arranged in the same manner as described above. Missing can be designed.
In a pattern group including a plurality of main patterns 1 arranged close to each other (each of which is close to at least one of the others), the number of the main patterns 1 included is N, and the total number of compartments of the auxiliary pattern 2 is K. and when,
K ≦ (8-1) N
Can be.

In FIGS. 11 (f) to 11 (i), only the case where the second main pattern 1b approaches the first main pattern 1a in the X direction (horizontal direction in the figure) is illustrated, but it approaches in the Y direction. In the same manner as described above, the auxiliary pattern 2 in which any one of the eight sections is omitted can be arranged.

Further, the present invention can be effectively applied even when the second main pattern 1b approaches the first main pattern 1a from an oblique direction, such as when the second main pattern 1b approaches from the diagonal direction of the main pattern 1. Even in that case, of the eight sections of the auxiliary pattern 2a attached to the first main pattern 1a, at least one section facing the second main pattern 1b side may be omitted.

Further, when the third main pattern and the fourth main pattern are arranged closer to the first main pattern, among the eight sections of the auxiliary patterns attached to each main pattern, as described above, The compartments facing each other can be omitted. In that case, depending on the relative arrangement of the plurality of main patterns, in addition to the main pattern having the auxiliary pattern of seven sections and the main pattern having the auxiliary pattern of five sections, six sections, four sections, three sections, two sections, and further May have a main pattern with a compartmentalized auxiliary pattern.
For example, the two main patterns can be a pattern group having auxiliary patterns missing one section from each other, or a pattern group having auxiliary patterns missing three sections from each other.
Alternatively, the three main patterns can be a pattern group having an auxiliary pattern lacking one or two compartments, respectively, depending on the arrangement (X direction, Y direction, or X and Y directions, and the same applies hereinafter).
Depending on the arrangement of the four main patterns, each of the four main patterns can be a pattern group having an auxiliary pattern lacking 1 to 5 sections.
Hereinafter, five, six, or seven main patterns are used as an auxiliary pattern group in which 1 to 6 sections are missing due to the arrangement, or 8 main patterns are missing 1 to 7 sections, respectively, due to the arrangement. It is also possible to make a pattern group having an auxiliary pattern.
On the other hand, the auxiliary pattern included in one main pattern may have no omissions other than the compartments on the side facing the other main pattern or the compartments on both sides thereof.

Further, the diameter of the hole pattern formed on the transferred body may be a different value in the X direction and the Y direction depending on the approaching direction of the plurality of hole forming patterns. This is because the change in the optical image caused by the lack of a part of the auxiliary pattern occurs unevenly in the X direction and the Y direction. Therefore, for the purpose of compensating for the influence on the optical image having unevenness in the X direction and the Y direction, it is useful to apply mask bias β2 having different dimensions in the X direction and the Y direction to the drawing data of the pattern.

For example, as shown in FIG. 7A, the first main pattern 1a and the second main pattern 1b are arranged in the X direction, and among the auxiliary patterns 2a and 2b attached to both main patterns 1a and 1b, they face each other. When the section to be used (that is, the section extending in the Y direction) is omitted, the amount given in the X direction is β2 (x) for the mask bias β2 (μm) given to the dimensions of the first main pattern 1a and the second main pattern 1b. ), When the amount given in the Y direction is β2 (y), β2 (y)> β2 (x) can be set.
Specifically, a positive bias in the direction perpendicular to the direction in which the auxiliary pattern is missing (X direction in FIG. 7A) and the Y direction in FIG. 7A when viewed from the main pattern. Add β2 (y). Further, if necessary, a negative value bias β2 (x) can be applied in the direction in which the auxiliary pattern is missing (X direction in FIG. 7A).

FIG. 13 illustrates a transfer pattern of a photomask including the main patterns 1a and 1b to which the mask bias β2 is applied. Here, as a result of adding the mask bias, the dimensions of the main patterns 1a and 1b in the X direction are smaller than the dimensions in the Y direction, and the shapes of the main patterns 1a and 1b are vertically long rectangles.

In the aspect of FIG. 11 (g), the hole pattern formed on the transferred object as a transfer image of the square main patterns 1a and 1b is a horizontally long rectangle. Therefore, if the shapes of the main patterns 1a and 1b are made vertically long rectangles by applying the mask bias, it is possible to eliminate the error in the pattern dimensions caused by the omission of some sections of the auxiliary patterns 2a and 2b. As a result, it is possible to form a hole pattern in which the dimensions in the X direction and the dimensions in the Y direction are equal on the transferred body. Therefore, by optical simulation, the bias amount β2 for making the dimensions in the X direction and the Y direction equal on the transferred object is obtained for each of the X direction and the Y direction, and this is reflected in the pattern drawing data. Just do it.

Therefore, in the transfer pattern of the photomask, the main pattern to which the bias β2 is applied becomes a rectangle. That is, the first main pattern 1a is a rectangle having a long side on the side facing the second main pattern 1b at a close position.
In the arrangement example as shown in FIG. 13 described above, when the main pattern before applying the bias β2 is a square having a pattern width W1, the long side W3 (y) of the main pattern is W3 (y) = W1 + β2 (y). ), And the short side W3 (x) becomes W3 (x) = W1 + β2 (x). Then, W3 (x) and W3 (y) preferably satisfy the following equations.
For the long side,
0.8 ≦ W3 (y) ≦ 4.0, more preferably 1.0 ≦ W3 (y) <3.5
For the short side,
0.8 ≦ W3 (x) ≦ 4.0, more preferably 1.0 ≦ W3 (x) ≦ 3.0

As described above, when the photomask of the present embodiment is used as a photomask for manufacturing a display device, that is, when the photomask of the present embodiment is used in combination with a photoresist for manufacturing a display device, it is on the transferred object. It is possible to significantly reduce the loss of the resist film thickness in the portion corresponding to the auxiliary pattern.

<Manufacturing method of photomask>
Next, an example of a method for producing a photomask applicable to the embodiment of the present invention will be described below with reference to FIGS. 14 (a) to 14 (f). In FIGS. 14 (a) to 14 (f), a cross-sectional view is shown on the left side and a plan view is shown on the right side, and for simplification, the photomask pattern shape shows only the first main pattern and the auxiliary pattern accompanying the first main pattern. ing.

First, as shown in FIG. 14A, a photomask blank 30 is prepared. In the photomask blank 30, a phase shift film 11 and a low translucency film 12 are formed in this order on a transparent substrate 10 made of glass or the like, and a first photoresist film 13 is further applied.

The phase shift film 11 is formed on the main surface of the transparent substrate 10. When any of i-line, h-line, and g-line is used as the representative wavelength of the exposure light, the phase shift film 11 has a transmittance T1 (%) with respect to the representative wavelength, preferably more than 20 to 80 (%). Is 30 to 75 (%), more preferably 40 to 75 (%). The phase shift amount of the phase shift film 11 with respect to the representative wavelength is approximately 180 degrees. In this way, the phase shift film 11 makes it possible to set the phase difference of the transmitted light between the main pattern composed of the translucent portion and the auxiliary pattern composed of the phase shift portion to be approximately 180 degrees. Such a phase shift film 11 shifts the phase of light having a representative wavelength in the wavelength range of i-line to g-line by approximately 180 degrees. As a method for forming the phase shift film 11, a known method such as a sputtering method can be applied.

It is desirable that the phase shift film 11 is made of a material that satisfies the above transmittance and phase difference and can be wet-etched as described below. However, if the amount of side etching generated during wet etching becomes too large, inconveniences such as deterioration of CD accuracy and destruction of the upper layer film due to undercut occur. Therefore, the film thickness of the phase shift film 11 is preferably 2000 Å or less, preferably 300 to 2000 Å, and more preferably 300 to 1800 Å.

Further, in order to satisfy these conditions, the material of the phase shift film 11 has a refractive index of a representative wavelength (for example, h line) contained in the exposure light, preferably 1.5 to 2.9. More preferably, it is 1.8 to 2.4.

Further, in order to sufficiently exert the phase shift effect, it is preferable that the pattern cross section (surface to be etched) by wet etching is close to perpendicular to the main surface of the transparent substrate 10.

Considering the above properties, the material of the phase shift film 11 is a material containing any of Zr, Nb, Hf, Ta, Mo, Ti and Si, or oxides, nitrides, and oxide nitrides of these materials. , Carbides, or materials containing carbides of oxide and nitrides can be used.

A low translucency film 12 is formed on the phase shift film 11. As a method for forming the low light-transmitting film 12, a known means such as a sputtering method can be applied as in the case of the phase shift film 11.
Further, the wavelength dependence of the phase shift amount of the phase shift film 11 preferably has a fluctuation range of 40 degrees or less with respect to the i-line, h-line, and g-line.

The low light-transmitting film 12 can be formed of a light-shielding film that does not substantially transmit exposure light. In addition to this, the low translucency film 12 can also be formed of a film having a predetermined low transmittance with respect to the representative wavelength of the exposure light. The low transmissive film 12 used in the production of the photomask of the present embodiment has a transmittance lower than the transmittance T1 (%) of the phase shift film 11 with respect to light having a representative wavelength in the wavelength range of i-line to g-line. It has T2 (%).

When the low transmissive film 12 transmits the exposure light with a low transmittance, the transmittance and the phase shift amount of the low transmissive film 12 with respect to the exposure light are the transmittance of the low transmissive portion of the photo mask of the present embodiment. And it is required that the phase shift amount can be achieved. Preferably, in the laminated state of the phase shift film 11 and the low translucency film 12, the transmittance T3 (%) with respect to the light of the representative wavelength of the exposure light is T3 ≦ 20, and the phase shift amount φ3 is preferable. Is 90 (degrees) or less, more preferably 60 (degrees) or less.

The single property of the low translucency film 12 is that it does not substantially transmit light of the above-mentioned representative wavelength, or has a transmittance (T2 (%)) of less than 30 (%) (that is, 0). It is preferable that <T2 <30) and the phase shift amount (φ2) are approximately 180 degrees. Approximately 180 degrees means 120 to 240 degrees. Preferably, the phase shift amount φ2 is 150 to 210 (degrees).

The material of the low translucency film 12 may be Cr or a compound thereof (oxide, nitride, carbide, oxynitride, or carbide oxide), or a metal containing Mo, W, Ta, and Ti. It may be festival or the above compound of the silicide. However, the material of the low light-transmitting film 12 is preferably a material that can be wet-etched like the phase-shift film 11 and has etching selectivity with respect to the material of the phase-shift film 11. That is, it is desirable that the low light-transmitting film 12 has resistance to the etching agent of the phase shift film 11, and the phase shift film 11 has resistance to the etching agent of the low light transmission film 12.

The first photoresist film 13 is coated on the low translucency film 12. Since the photomask of the present embodiment is preferably drawn by a laser drawing apparatus, a photoresist suitable for it is used. The photoresist constituting the first photoresist film 13 may be a positive type or a negative type, but will be described below as a positive type photoresist.

Next, as shown in FIG. 14 (b), the first photoresist film 13 is drawn with drawing data based on the transfer pattern using a drawing device (first drawing). Then, the low translucent film pattern 12p is formed by wet etching the low translucent film 12 using the first resist pattern 13p obtained by development as a mask. At this stage, a region to be a low light-transmitting portion is defined, and a region of an auxiliary pattern (low light-transmitting film pattern 12p) surrounded by the low light-transmitting portion is defined. As the etching solution (wet etchant) for wet etching, a known etching solution suitable for the composition of the low light transmissive film 12 to be used can be used. For example, in the case of a film containing Cr, dicerium ammonium nitrate or the like can be used as the wet etchant.

Next, as shown in FIG. 14 (c), the first resist pattern 13p is peeled off. As a result, the low translucent film pattern 12p and a part of the phase shift film 11 are exposed.

Next, as shown in FIG. 14D, the second photoresist film 14 is applied to the entire surface including the low translucent film pattern 12p.

Next, as shown in FIG. 14 (e), a second drawing is performed on the second photoresist film 14, and then 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 light-transmitting film pattern 12p as masks. By this etching (development), the main surface of the transparent substrate 10 is exposed as a translucent portion, whereby a region of the main pattern composed of the translucent portion is defined.

The second resist pattern 14p covers the region serving as the auxiliary pattern and has an opening in the region of the main pattern composed of the translucent portion. In that case, it is preferable to perform sizing on the drawing data of the second drawing so that the edge portion of the low translucent film pattern 12p is exposed inside the opening edge of the second resist pattern 14p. By doing so, it is possible to absorb the misalignment that occurs between the first drawing and the second drawing and prevent deterioration of the CD accuracy of the transfer pattern.

That is, if the second resist pattern 14p is sized at the time of the second drawing, the phase shift film 11 and the low translucency film 12 can be patterned when an isolated hole pattern is to be formed on the transferred object. There will be no misalignment. Therefore, in the transfer pattern as illustrated in FIG. 1, the centers of gravity of the main pattern 1 and the auxiliary pattern 2 can be precisely matched.

The wet etching used for etching the phase shift film 11 is appropriately selected according to the composition of the phase shift film 11.

Next, as shown in FIG. 14 (f), the second resist pattern 14p is peeled off. As a result, a photomask having a transfer pattern is completed. In addition, although FIG. 14 shows a case where a regular octagonal auxiliary pattern without missing sections is formed, when any of the eight sections is missing, the area of the auxiliary pattern is defined in FIG. 14 (b). At that time, the drawing data may be changed according to the position and size of the section to be omitted.

In the production of the photomask, the etching applicable when patterning an optical film such as the phase shift film 11 or the low light transmissive film 12 includes dry etching and wet etching. Either may be adopted, but wet etching is particularly advantageous in the present invention. This is because photomasks for manufacturing display devices are relatively large in size, and there are many types of sizes. If dry etching that requires a vacuum chamber is applied when manufacturing such a photomask, the size of the dry etching apparatus will be increased and the efficiency of the manufacturing process will be reduced.

However, there are also problems associated with applying wet etching when manufacturing such a photomask. Since wet etching has the property of isotropic etching, when a predetermined film is etched and eluted in the depth direction, the etching proceeds in the direction perpendicular to the depth direction. For example, when the phase shift film 11 having a film thickness of F (nm) is etched to form a slit, the opening of the resist pattern serving as an etching mask is 2F (nm) (that is, one side F (nm)) from the desired slit width. ), But the finer the width of the slit, the more difficult it is to maintain the dimensional accuracy of the resist pattern opening. Therefore, it is useful that the width d of the auxiliary pattern is 1 μm or more, preferably 1.3 μm or more.

Further, when the film thickness F (nm) is large, the side etching amount is also large, so it is advantageous to use a film material having a phase shift amount of about 180 degrees even if the film thickness is small. Therefore, it is desired that the refractive index of the phase shift film 11 is high with respect to the representative wavelength of the exposure light. Specifically, the phase shift film 11 is formed by using a material having a refractive index of preferably 1.5 to 2.9, more preferably 1.8 to 2.4 with respect to the representative wavelength. It is preferable to do so.

The present invention includes a method for manufacturing a display device, which comprises a step of exposing with an exposure device using the photomask of the present embodiment and transferring the transfer pattern onto a transfer target.

In the method for manufacturing the display device of the present invention, first, the photomask of the present embodiment is prepared. Next, the transfer pattern is exposed by using an exposure device having a numerical aperture (NA) of 0.08 to 0.15 and an exposure light source including i-line, h-line, and g-line, and the transferred object is transferred. A hole pattern having a diameter W2 of 0.8 to 3.0 (μm) is formed on the top. It is common and advantageous to apply 1x exposure to the exposure.

When transferring the transfer pattern using the photomask of the present embodiment, reduced exposure may be used, but as an exposure machine used for a photomask for manufacturing a display device, a method of performing projection exposure at the same magnification. The following are preferable. For example, the numerical aperture (NA) of an optical system is
0.08 ≤ NA <0.20,
More preferably
0.08 ≤ NA ≤ 0.15,
Furthermore,
0.08 <NA <0.15
Is desirable.
In addition, σ (coherence factor) is
0.4 ≤ σ ≤ 0.9
More preferably
0.4 <σ <0.7
More preferably
0.4 <σ <0.6
Is.
As the exposure light source, a light source that includes at least one of i-line, h-line, and g-line in the exposure light is used. When applying exposure light of a single wavelength, it is preferable to use i-line. On the other hand, using a light source containing all of i-line, h-line, and g-line (also referred to as a broad wavelength light source) is useful in terms of securing a sufficient amount of light.

Further, the light source of the exposure apparatus to be used may be oblique light illumination (ring band illumination or the like), but the excellent effect of the present invention can be sufficiently obtained by using normal illumination to which oblique illumination is not applied.

According to the present invention, in the method of manufacturing a display device using a mask for manufacturing a display device, transfer onto a transfer target can be stably performed even with a fine dense pattern. Specifically, it is possible to precisely form a hole pattern while ensuring the process margin of manufacturing such as DOF and MEEF. Further, when forming the dense pattern, the thickness of the resist pattern formed on the transferred body can be sufficiently secured. This enhances CD accuracy in display device production and provides industrial benefits such as stable production and high yield.

1 (1a, 1b) ... Main pattern 2 (2a, 2b) ... Auxiliary pattern 3 ... Low translucency part 4 ... Translucency part 5 ... Phase shift part 10 ... Transparent substrate 11 ... Phase shift film 12 ... Low translucency film

Claims (8)

A photomask for manufacturing a display device, which has a transfer pattern formed by patterning an optical film formed on the main surface of a transparent substrate.
The transfer pattern is
A main pattern consisting of a quadrangular translucent part whose main surface is exposed ,
Includes an auxiliary pattern consisting of a phase shift portion arranged around the main pattern, and a low light transmissive portion formed in a region other than the main pattern and the auxiliary pattern.
When defining a regular octagonal band of a predetermined width that surrounds the main pattern around the main pattern, the auxiliary pattern constitutes at least a part of the regular octagonal band.
When one of the plurality of main patterns included in the transfer pattern is used as the first main pattern, a second main pattern different from the first main pattern is arranged at a position close to the first main pattern.
Of the eight sections constituting the regular octagonal band surrounding the first main pattern, an auxiliary pattern having a gap in one section facing the second main pattern side is arranged around the first main pattern and ,
The second main pattern surrounding the one of the equilateral constituting the rectangular band eight compartments, the first main pattern side auxiliary pattern of missing a section facing is Rukoto disposed around the second main pattern A photomask for manufacturing display devices. When the diameter of the main pattern is W1, the transfer pattern is characterized in that a hole pattern having a diameter of W2 (however, W1 ≧ W2) is formed as a transfer image of the main pattern on the transferred object. The photomask for manufacturing a display device according to claim 1. When the arrangement direction of the first main pattern and the second main pattern is the X direction, the dimension of the first main pattern in the X direction is smaller than the dimension in the Y direction perpendicular to the X direction. , A photomask for manufacturing a display device according to claim 1 or 2. The transfer pattern includes a dense pattern in which three or more main patterns are regularly arranged in the X direction, the Y direction perpendicular to the X direction, or the X direction and the Y direction, and constitutes the dense pattern. The present invention according to any one of claims 1 to 3, wherein each of the main patterns to be used has the auxiliary pattern lacking at least one of the eight sections facing the other main pattern side. Photomask for manufacturing display devices. The phase shift portion is formed on the transparent substrate by forming a phase shift film having a transmittance of 20 to 80% with respect to a representative wavelength of the exposure light and shifting the phase of the exposure light by approximately 180 degrees. The photomask for manufacturing a display device according to any one of claims 1 to 4, which is characterized. The photomask for manufacturing a display device according to any one of claims 1 to 5, wherein the low light-transmitting portion is a light-shielding portion having an optical density OD of 2 or more with respect to exposure light. The display device for manufacturing according to any one of claims 1 to 6, wherein the straight line connecting the center of gravity of the first main pattern and the center of gravity of the second main pattern does not cross the auxiliary pattern. Photomask. The step of preparing the photomask according to any one of claims 1 to 7 and
The transfer pattern is exposed by using an exposure device having an exposure light source having a numerical aperture (NA) of 0.08 to 0.15 and containing at least one of i-line, h-line, and g-line. A method for manufacturing a display device, which comprises a step of forming a hole pattern having a diameter W2 of 0.8 to 3.0 (μm) on a transfer target.