TWI658320B - Method of transferring a pattern and method of manufacturing a display device - Google Patents

Abstract

An object of the present invention is to obtain an excellent photomask suitable for an exposure environment of a photomask for display device manufacturing and capable of stably transferring a fine pattern and a method for manufacturing the same. The photomask of the present invention includes a pattern for transfer formed on a transparent substrate, and the pattern for transfer has a main pattern with a diameter of W1 (μm), is arranged near the main pattern, and has a width of d (μm). The auxiliary pattern and the low-light-transmitting portion arranged in a region other than the main pattern and the auxiliary pattern. The phase difference between the representative wavelengths passing through the main pattern and the auxiliary pattern is approximately 180 degrees, and the diameter W1, the width d, The transmittance T1 (%) of the auxiliary pattern, the transmittance T3 (%) of the low-light-transmitting portion, and the distance P (μm) between the center of the main pattern and the center of the auxiliary pattern in the width direction have a specific relationship.

Description

Pattern transfer method and manufacturing method of display device

The present invention relates to a photomask that is favorably used for the manufacture of a display device typified by liquid crystal or organic EL (Electroluminescence) and a method for manufacturing a display device using the photomask.

In Patent Document 1, as a mask for manufacturing a semiconductor device, there is described a phase shift mask in which four auxiliary light-transmitting sections are arranged in parallel with each side of the main light-transmitting section (hole pattern), and the main The phase of the light of the light transmitting portion and the auxiliary light transmitting portion is reversed.

Patent Document 2 describes a large-scale phase shift mask having a transparent substrate and a translucent phase shift film formed on the transparent substrate.

[Prior technical literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 3-15845

[Patent Document 2] Japanese Patent Laid-Open No. 2013-148892

At present, display devices including a liquid crystal display device or an EL display device are desired. Brighter and power saving, and improve display performance such as high definition, high speed display, wide viewing angle.

For example, for a thin film transistor ("TFT") used in the above display device, if the contact holes formed in the interlayer insulating film among the plurality of patterns constituting the TFT are not provided with the upper and lower layers, The function of pattern connection cannot guarantee correct operation. On the other hand, in order to maximize the aperture ratio of the display device, to make a bright and power-saving display device, the diameter of the contact hole is required to be sufficiently small. Accordingly, it is expected that the diameter of the hole pattern provided in the photomask used to form such a contact hole is also miniaturized (for example, less than 3 μm). For example, a hole pattern having a diameter of 2.5 μm or less and further a diameter of 2.0 μm or less is required. In the near future, it is considered that a pattern having a diameter of less than 2.0 μm and 1.5 μm or less is also desired. According to such a background, a manufacturing technology of a display device capable of reliably transferring minute contact holes is required.

In addition, in the field of manufacturing a photomask for a semiconductor device (LSI (Large Scale Integration)) that has a higher integration degree than a display device and a significant improvement in pattern miniaturization, in order to obtain a higher Resolution, it is used in the exposure device to apply high NA (Numerical Aperture, numerical aperture) (such as 0.2 or more) optical system, and to promote the process of shortening the wavelength of exposure light, and more use of KrF or ArF excimer laser (Single wavelengths of 248nm and 193nm, respectively).

On the other hand, in the field of lithography for display device manufacturing, in order to improve the resolution, the method described above is generally not applied. On the contrary, there is a tendency that by using known exposure devices such as LCD (liquid crystal display, liquid crystal display device), the NA of the exposure device is about 0.08 to 0.10, and the exposure light source also includes a wide wavelength of i rays, h rays, and g rays. Area, but rather focus on production efficiency and cost than resolution or focus depth.

However, as described above, in the manufacture of display devices, the demand for pattern miniaturization has never been higher. Therefore, if the technology for semiconductor device manufacturing is directly applied to the display device manufacturing Manufacturing, there are several problems. For example, when switching to an exposure device with a high NA (numerical aperture) and high resolution, a large investment is required, and it is not possible to obtain a match with the price of a display device. Or, regarding the change of exposure wavelength (using a short wavelength like ArF excimer laser with a single wavelength), it is more difficult to apply a display device with a large area. If it is applied, the production efficiency will decrease, and it still needs to be quite Large investments are not appropriate in the above respects.

Furthermore, as described below, a mask for a display device has various problems that are different from the constraints or unique to the manufacture of a mask for the manufacture of a semiconductor device.

Based on the above, it is actually difficult to directly convert the photomask of Patent Document 1 into a display device manufacturing. Further, it is described that the light intensity distribution of the halftone type phase shift mask described in Patent Document 2 is improved as compared with the binary mask, but there is room for further improvement in performance.

Therefore, in a manufacturing method of a display device using a photomask for manufacturing a display device, it is desirable to overcome the above-mentioned problems, realize a fine pattern, and stably transfer to a transfer target. Therefore, an object of the present invention is to obtain an excellent photomask that is suitable for an exposure environment of a photomask for display device manufacturing, and capable of stably transferring a fine pattern, and a method for manufacturing the same.

In order to solve the above problems, the present invention has the following configuration. The photomask of the present invention is characterized by the following configuration 1 to 14, and the manufacturing method of the display device of the present invention is characterized by the following configuration 15.

(Composition 1)

Structure 1 of the present invention is a photomask, characterized in that it includes a transfer pattern formed on a transparent substrate, and the transfer pattern has a main pattern with a diameter of W1 (μm) and is arranged on the main The auxiliary pattern in the vicinity of the pattern and having a width of d (μm), and the low-light-transmitting portion arranged in the area where the main pattern and the auxiliary pattern are formed are in the i-light transmitting the main pattern The phase difference between the representative wavelength of the wavelength range of the line ~ g light and the representative wavelength passing through the auxiliary pattern is approximately 180 degrees, and the transmittance of the light representing the representative wavelength passing through the auxiliary pattern is set to T1 (%), When the transmittance of the light of the representative wavelength transmitted through the low-light transmission portion is T3 (%), and the distance between the center of the main pattern and the center of the width direction of the auxiliary pattern is set to P (μm), the following is satisfied: Expressions (1) ~ (4): 0.8 ≦ W1 ≦ 4.0‧‧‧‧‧ (1)

1.0 <P ≦ 5.0‧ (3)

T3 <T1 ‧ ‧

(Composition 2)

Structure 2 of the present invention is the photomask according to Structure 1, wherein the auxiliary pattern is formed on the transparent substrate by forming a translucent film having a transmittance T1 (%) for light of the representative wavelength.

(Composition 3)

The third configuration of the present invention is the photomask of the second configuration, wherein the transmittance T1 (%) of the translucent film satisfies the following formula (5): 30 ≦ T1 ≦ 80‧‧‧ (5).

(Composition 4)

The fourth aspect of the present invention is the photomask of the second or third aspect, wherein the width d of the auxiliary pattern is 1 (μm) or more.

(Composition 5)

Structure 5 of the present invention is the photomask according to any one of Structures 2 to 4, wherein the main pattern is formed by exposing a part of the main surface of the transparent substrate, and the auxiliary pattern is described above. The translucent film is formed on a transparent substrate, and the low-transmittance part is laminated on the transparent substrate in order or in reverse order. The transmissivity of the translucent film and the light of the representative wavelength is T2 (%). Made of low light transmission film.

(Composition 6)

Structure 6 of the present invention is the photomask according to any one of Structures 2 to 4, wherein the main pattern is formed by forming an etched portion on the main surface of the transparent substrate, and the auxiliary pattern is formed on the transparent substrate. The semi-transparent film is formed, and the low-transmissive part is a laminated layer of the semi-transparent film and the light having a representative wavelength of T2 (%), which are laminated on the transparent substrate in order or in reverse order. Made of light film.

(Composition 7)

Structure 7 of the present invention is the photomask according to any one of Structures 2 to 6, wherein the translucent film includes a material containing at least one of Zr, Nb, Hf, Ta, Mo, and Ti and Si, Or materials containing oxides, nitrides, oxynitrides, carbides, or oxynitrides of such materials.

(Composition 8)

The eighth aspect of the present invention is the photomask according to the first aspect, wherein the auxiliary pattern is formed by exposing the transparent substrate.

(Composition 9)

Structure 9 of the present invention is the photomask of Structure 8, wherein the main pattern is formed by forming an etched portion on the main surface of the transparent substrate, and the auxiliary pattern is formed by exposing a part of the main surface of the transparent substrate. The low-light-transmitting portion is formed on the transparent substrate by forming a low-light-transmitting film having a light transmittance of T3 (%) of the light of the representative wavelength.

(Composition 10)

The structure 10 of the present invention is the photomask according to the structure 8, wherein the main pattern is formed by exposing a part of the main surface of the transparent substrate, and the auxiliary pattern is formed by forming an etched portion on the main surface of the transparent substrate. The low-light-transmitting portion is formed on the transparent substrate by forming a low-light-transmitting film having a light transmittance of T3 (%) of the light of the representative wavelength.

(Composition 11)

The constitution 11 of the present invention is the photomask according to any one of constitutions 1 to 10, characterized in that it corresponds to the above-mentioned main pattern to form a transfer diameter W2 of 3.0 (μm) or less on the object to be transferred (wherein W1> W2).

(Composition 12)

The structure 12 of the present invention is the photomask according to the structure 11, wherein the difference W1-W2 between the diameter W1 of the main pattern and the transfer diameter W2 on the transferee is set as a deviation β (μm). ), 0.2 ≦ β ≦ 1.0‧‧‧ (6).

(Composition 13)

The structure 13 of the present invention is the photomask according to any one of the structures 1 to 12, characterized in that the above-mentioned transmittance T3 (%) of the low-light transmission portion to the light of the representative wavelength satisfies T3 <30‧‧‧ (7).

(Composition 14)

The structure 14 of the present invention is the photomask according to any one of the structures 1 to 12, wherein the low-light-transmitting portion does not substantially transmit light of the representative wavelength.

(Composition 15)

Composition 15 of the present invention is a method for manufacturing a display device, which includes the following steps: preparing a photomask as in any of 1 to 14; using a numerical aperture (NA) of 0.08 to 0.20 and having An exposure device including an exposure light source including at least one of i-ray, h-ray, and g-ray, exposes the above-mentioned transfer pattern, and forms a hole pattern with a diameter W2 of 0.6 to 3.0 (μm) on the transferee. .

According to the present invention, it is possible to provide an excellent photomask suitable for an exposure environment of a photomask for display device manufacturing and capable of stably transferring a fine pattern and a method for manufacturing the same.

FIG. 1 is a schematic plan view of an example of a photomask of the present invention.

FIG. 2 is a plan view (a) to (f) of other examples of the photomask of the present invention.

Fig. 3 shows examples (a) to (f) of the layer configuration of the photomask of the present invention.

4 (a) to 4 (f) are a schematic sectional view and a schematic plan view showing an example of a manufacturing process of a photomask of the present invention.

FIG. 5 is a schematic plan view of the photomasks of Comparative Examples 1-1 and 1-2 and Example 1, and is a view showing the transfer performance of size and optical simulation.

FIG. 6 shows (a) a spatial image of the light intensity formed on a transfer target when using the photomasks of Comparative Examples 1-1 and 1-2 and Example 1, and A cross-sectional view of the formed resist pattern.

FIG. 7 is a schematic plan view of the photomasks of Comparative Examples 2-1 and 2-2 and Example 2, and is a view showing the transfer performance of size and optical simulation.

FIG. 8 shows (a) a spatial image of the light intensity formed on the transfer target when using the photomasks of Comparative Examples 2-1 and 2-2 and Example 2, and A cross-sectional view of the formed resist pattern.

If the CD (Critical Dimension (Critical Dimension), which is used as the pattern line width) of the photomask for the transfer mask is miniaturized, it will be more difficult to accurately transfer it to the object to be transferred. (Etched film, etc., also referred to as a workpiece). In the exposure device for display devices, the resolution limit shown in the specifications is usually about 2 to 3 μm. On the other hand, in the transfer pattern to be formed, sizes close to or smaller than this have appeared. Furthermore, since the area of the photomask for display device manufacturing is larger than that for semiconductor device manufacturing, in actual production, it is difficult to transfer the transfer pattern with a CD of less than 3 μm uniformly on the surface.

Therefore, it is necessary to study factors other than pure resolution (based on the exposure wavelength and the numerical aperture of the exposure optical system) to effectively improve the transfer performance.

Furthermore, since the area of the object to be transferred (flat panel display substrate) is large, the step of pattern transfer by exposure can also be referred to as an environment where defocus is easily caused by the flatness of the surface of the object to be transferred. Under this environment, it is extremely meaningful to sufficiently ensure the focus margin (DOF (Depth of Focus)) at the time of exposure.

In addition, as is well known, the size of the photomask used in the manufacture of the display device is large, and in the wet processing (development or wet etching) in the photomask manufacturing step, the CD (line width) is ensured at all positions in the plane. Uniformity is not easy. In order to control the final CD accuracy within the specified tolerance range, it is also important to ensure a sufficient depth of focus (DOF) in the exposure step, and ideally, other performances will not be accompanied by deterioration.

The present invention is a photomask provided with a pattern for transfer. The pattern for transfer is formed on a transparent substrate and formed by patterning a semi-transmissive film and a low-transmittance film, respectively. FIG. 1 illustrates a schematic plan view of a transfer pattern included in the photomask of the present invention.

As shown in FIG. 1, a transfer pattern formed on a transparent substrate includes a W1 (μm) diameter The main pattern and the auxiliary pattern having a width d (μm) arranged near the main pattern. A low-light-transmitting portion is formed in a region other than the main pattern and the auxiliary pattern.

Here, the transmittance of light of a representative wavelength in a wavelength region of i rays to g rays of the auxiliary pattern is set to T1, and the transmittance of light of the representative wavelength that passes through a low-light transmission portion is set to T3. The distance between the center of the main pattern and the center of the auxiliary pattern in the width direction is defined as P (μm). At this time, the photomask of the present invention satisfies the following relationship.

0.8 ≦ W1 ≦ 4.0 ‧ ‧ ‧ ‧ ‧ (1)

1.0 <P ≦ 5.0‧ (3)

T3 <T1 (4)

In the above formula, T1 is preferably T1 ≧ 30.

The light transmittances T1 and T3 are based on the transmittance of the transparent substrate, and are determined by the layer structure of the part.

A cross-sectional schematic diagram of such a transfer pattern can be, for example, one shown in FIG. 3 (a). This will be described as a first aspect of the photomask of the present invention, and described with reference to FIG. 3 (a).

In this aspect, the main pattern includes a light transmitting portion exposed by the transparent substrate. Furthermore, a film having a high transmittance may be formed on the main pattern. However, in terms of obtaining the maximum transmittance, it is preferable that a film having a high transmittance is not formed in the main pattern, and that the transparent substrate is exposed.

In addition, the auxiliary pattern in this aspect includes a translucent portion formed by forming a translucent film on the transparent substrate. The translucent film has a phase shift amount that substantially shifts light of a representative wavelength in a wavelength range of i-rays to g-rays by 180 degrees, and has a transmittance T1 (%) to the representative wavelength. In addition, a portion surrounding the main pattern and the auxiliary pattern becomes a low-light-transmitting portion formed by forming at least a low-light-transmitting film on the transparent substrate. That is, in the transfer pattern shown in FIG. 1, the area where the main pattern and the auxiliary pattern are formed is The outer area becomes a low-light transmission portion. As shown in FIG. 3 (a), in this aspect, the low-light-transmitting portion is formed by laminating a semi-light-transmitting film and a low-light-transmitting film on a transparent substrate. Furthermore, the low-light-transmitting portion can be laminated on the transparent substrate in order or in the reverse order to laminate the semi-transparent film and the low-light-transmitting film having a light transmittance of T2 (%) representing a wavelength of light.

The low-light-transmitting portion of the mask of the present invention has a specific low transmittance with respect to the representative wavelength of the exposed light. That is, for light having a representative wavelength in a wavelength range of i rays to g rays, the low-light-transmitting portion has a transmittance T3 (%) lower than the transmittance T1 (%) of the auxiliary pattern including the semi-light-transmitting portion. Therefore, in the present aspect of forming a low-light-transmitting portion by laminating a semi-light-transmitting portion and a low-light-transmitting portion (FIG. 3 (a)), as long as the layer is used, T3 <T1

The method is to select the transmittance T2 (%) of the low-transmittance film, and then adjust the transmittance T3 (%) of the low-transmittance portion.

Here, when the diameter (W1) of the main pattern is 4 μm or less, a fine main pattern having a diameter W2 (μm) (where W1> W2) can be formed on the object to be transferred corresponding to the main pattern ( Hole pattern).

Specifically, it is preferable to make W1 (μm) into the following formula (1) 0.8 ≦ W1 ≦ 4.0‧‧‧ (1)

Relationship. At this time, the diameter W2 (μm) of the main pattern (hole pattern) formed on the object to be transferred is 3.0 (μm) or less, and specifically, it can be set to 0.6 ≦ W2 ≦ 3.0.

The photomask of the present invention can be used for the purpose of forming a fine-sized pattern useful for the manufacture of a display device. For example, when the diameter W1 of the main pattern is 3.0 (μm) or less, the effect of the present invention is more significantly obtained. It is preferable to set the diameter W1 (μm) of the main pattern to 1.0 ≦ W1 ≦ 3.0.

In addition, although the relationship between the diameter W1 and the diameter W2 can be set to W1 = W2, it is preferable to set W1> W2. That is, when β (μm) is set as the deviation value, β = W1-W2> 0 (μm). At this time, 0.2 ≦ β ≦ 1.0, and more preferably 0.2 ≦ β ≦ 0.8.

When set in this manner, as described below, advantageous effects such as reduction in loss of the resist pattern on the transferred body can be obtained.

In the above, the diameter W1 of the main pattern means the diameter of a circle, or a value similar thereto. For example, when the shape of the main pattern is a regular polygon, the diameter W1 of the main pattern is the diameter of the inscribed circle. If the shape of the main pattern is a square as shown in FIG. 1, the diameter W1 of the main pattern is the length of one side. The diameter W2 of the transferred main pattern is also the same as the diameter of a circle or a numerical value similar thereto.

Of course, when it is desired to form a finer pattern, W1 can be set to 2.5 (μm) or less, or 2.0 (μm) or less, and W1 can be set to 1.5 (μm) or less to apply the present invention.

Furthermore, the diameter W1 of the main pattern in the photomask of the present invention, the diameter W2 of the main pattern on the transferred body, and the above-mentioned preferable range related to the setting of the deviation are in the following second to sixth aspects. The same can be applied to the photomask of the invention.

The phase difference between the main pattern and the auxiliary pattern for the representative wavelength of the exposed light for the exposure of the photomask of the present invention having such a pattern for transfer It's about 180 degrees. That is, the phase difference between the above-mentioned representative wavelength of light transmitted through the main pattern and the above-mentioned representative wavelength transmitted through the auxiliary pattern 1 becomes approximately 180 degrees. About 180 degrees means 120 to 240 degrees. Phase difference 1 is preferably 150 to 210 degrees, and more preferably 170 to 190 degrees.

Furthermore, the photomask of the present invention has a significant effect when using exposure light including i-rays, h-rays, or g-rays, so it is possible to use exposure light including at least one of i-rays, h-rays, and g-rays. It is particularly preferable to use wide-wavelength light including i rays, h rays, and g rays as exposure light. In this case, as the representative wavelength, any of i-ray, h-ray, and g-ray may be used. For example, the h-ray can be used as a representative wavelength to form the photomask of the present invention.

In order to form such a phase difference, as long as the main pattern is a light-transmitting portion where the main surface of the transparent substrate is exposed, the auxiliary pattern is a semi-light-transmitting portion formed by forming a semi-transparent film on the transparent substrate, and the semi-transparent The phase shift amount of the optical film with respect to the representative wavelength may be set to approximately 180 degrees.

Furthermore, regarding the preferable range of the phase difference between the main pattern and the auxiliary pattern, and the wavelength of light used for the exposure of the photomask of the present invention, the same applies to the photomask of the present invention in the second to sixth aspects below. .

In the mask of the first aspect, that is, the mask shown in FIG. 3 (a), the light transmittance T1 of the semi-transmissive portion can be set as follows. That is, when the transmittance of the semi-transmissive film formed in the semi-transmissive portion to the representative wavelength is T1 (%), it is set to 30 ≦ T1 ≦ 80.

More preferably, it is 40 ≦ T1 ≦ 75.

The transmittance T1 (%) is the transmittance of the above-mentioned representative wavelength when the transmittance of the transparent substrate is used as a reference.

In the photomask of the present invention, it is arranged in a region other than the main pattern and the auxiliary pattern, The low-light-transmitting portion formed around the main pattern and the auxiliary pattern can be configured as follows.

The low-light-transmitting portion may also be one that does not substantially allow light to be exposed (light having a representative wavelength in a wavelength range of i rays to g rays) to pass through. In this case, the low-light-transmittance film alone can be used as a low-light-transmittance film that does not substantially transmit the above-mentioned representative wavelength (that is, the light-shielding film) and has T2 ≦ 0.01 or an optical density OD ≧ 2. The laminated film of the low-light-transmitting film and the semi-light-transmitting film is a substantially light-shielding film (optical density OD ≧ 2).

Alternatively, the low-light-transmitting portion may be a person who transmits the exposed light within a specific range. However, in the case where the exposed light is transmitted in a specific range, the transmittance T3 (%) of the low-light-transmitting portion (here, when the semi-transmissive film and the low-transmissive film are laminated, the laminated film is the laminated film. Transmittance) satisfies T3 <T1.

Preferably, it satisfies 0.01 <T3 <30, and more preferably satisfies 0.01 <T3 ≦ 20.

The transmittance T3 (%) is also set as the transmittance of the above-mentioned representative wavelength based on the transmittance of the transparent substrate.

When such a low-light-transmitting portion transmits the exposed light at a specific transmittance, the phase difference between the transmitted light of the low-light transmitting portion and the transmitted light of the light-transmitting portion is different. 3 is preferably 90 ° or less, and more preferably 60 ° or less. If "90 degrees or less" is expressed in radians, it means that the phase difference is "(2n-1 / 2) π ~ (2n + 1/2) π (where n is an integer)". In the same manner as above, the phase difference of the representative wavelength included in the exposed light is calculated.

Therefore, in this case, it is preferable that the low-light-transmittance film used as the mask of this aspect alone has a transmittance (T2 (%)) of less than 30 (%) (that is, 0 <T2 < 30), and the amount of phase shift ( 2) Approximately 180 degrees. About 180 degrees means 120 to 240 degrees. Phase difference 1 is preferably 150 to 210 degrees, and more preferably 170 to 190 degrees. With this, regarding the phase shift characteristics of the low-light-transmitting portion including the laminated layer, the 3 is set to the above range.

The transmittance here is also the same as above, and is set to the transmittance of the above-mentioned representative wavelength based on the transmittance of the transparent substrate.

In the above transfer pattern, when the width of the auxiliary pattern is set to d (μm),

When established, excellent effects of the invention can be obtained. That is, in When × d is within the above range, the amount of light transmitted through the auxiliary pattern and the amount of light transmitted through the main pattern interact in a well-balanced manner, and the transferability of the main pattern is improved.

At this time, the distance between the center of the main pattern and the center of the auxiliary pattern in the width direction is set as a pitch P (μm), and the pitch P is preferably 1.0 <P ≦ 5.0

The relationship is established.

More preferably, the pitch P can be set to 1.5 <P ≦ 4.5.

In the present invention, the auxiliary pattern has the effect of exerting an optical effect like a dense pattern with respect to the main pattern that is isolated in design. However, when the above relational expression is satisfied, the light of the main pattern and the auxiliary pattern is exposed. Good interactions can be exhibited with each other, showing excellent transferability as shown in the examples below.

The width d (μm) of the auxiliary pattern is a size below the resolution limit in the exposure conditions (exposure device used) of the photomask of the present invention. As a specific example, d ≧ 0.7, More preferably, d ≧ 0.8, and more preferably, the width d (μm) of the auxiliary pattern is 1 (μm) or more.

In addition, d ≦ W1 is preferable, and d <W1 is more preferable.

The relational formula (2) is more preferably the following formula (2) -1, and more preferably the following formula (2) -2.

As described above, the main pattern of the photomask shown in FIG. 1 is a square, but the present invention is not limited thereto. For example, as illustrated in FIG. 2, the main pattern of the photomask may be an octagon or a circularly symmetric shape. In addition, the center of rotational symmetry may be set as the center serving as the reference of P.

In addition, the shape of the auxiliary pattern of the photomask shown in FIG. 1 is an octagonal band, but the present invention is not limited to this. The shape of the auxiliary pattern is preferably a shape in which a certain width is given to the shape of the rotating object that is symmetrical three times or more with respect to the center of the hole pattern. The preferred shapes of the main pattern and the auxiliary pattern are the shapes illustrated in FIGS. 2 (a) ~ (f), and the design of the main pattern and the design of the auxiliary pattern can also be different from those shown in Fig. 2 (a) ~ (f) Combine each other.

For example, the case where the outer periphery of the auxiliary pattern is a regular polygon such as a square, a regular hexagon, a regular octagon, or a regular decagon (preferably a regular 2n polygon, where n is an integer of 2 or more) or a circle is illustrated. The shape of the auxiliary pattern is preferably a shape in which the outer periphery and the inner periphery of the auxiliary pattern are substantially parallel, that is, a shape such as a regular polygon having a certain width or a circular band. This belt shape is also called a polygonal belt or a circular belt. The shape of the auxiliary pattern is preferably a shape in which such a regular polygonal band or a circular band surrounds the periphery of the main pattern. At this time, the balance of the amounts of transmitted light of the main pattern and the transmitted light of the auxiliary pattern can be set to be approximately the same, so it is easy to obtain and obtain the present invention. The effect of light interaction.

In particular, when the photomask of the present invention is used as a photomask for the manufacture of a display device, that is, when the photomask of the present invention is used in combination with a photoresist for the manufacture of a display device, the number of transfers can be reduced. The resist on the part corresponding to the auxiliary pattern is lost.

Alternatively, the shape of the auxiliary pattern may be a shape that does not completely surround the periphery of the main pattern and that a part of the polygonal band or the circular band is missing. For example, the shape of the auxiliary pattern may be a shape lacking the corners of the quadrangular band as shown in FIG. 2 (f).

In addition, as long as the effect of the present invention is not hindered, other patterns may be used in addition to the main pattern and the auxiliary pattern of the present invention.

Hereinafter, an example of the manufacturing method of the mask of this aspect is demonstrated with reference to FIG.

As shown in FIG. 4 (a), a photomask base is prepared.

The photomask base is formed by sequentially forming a semi-transmissive film and a low-transmissive film on a transparent substrate including glass, and then coating a first photoresist film.

The translucent film is the following film: on the main surface of the transparent substrate, when any one of i rays, h rays, and g rays is set as a representative wavelength, the transmittance is 30 to 80 (%) (in When T1 (%) is set to transmittance, 30 ≦ T1 ≦ 80), more preferably 40 to 75 (%), and a phase shift amount with respect to the representative wavelength is approximately 180 degrees. With such a translucent film, the phase difference of the transmitted light between the main pattern including the translucent portion and the auxiliary pattern including the translucent portion can be set to approximately 180 degrees. Such a semi-transparent film shifts the phase of light representing a wavelength in a wavelength range of i rays to g rays by approximately 180 degrees. As a film-forming method of a semi-transparent film, a well-known method, such as a sputtering method, can be applied.

The semi-transparent film preferably satisfies the above-mentioned transmittance and phase difference, and includes a material capable of wet etching as described below. However, if the amount of side etching generated during wet etching is too large, it may cause deterioration of CD accuracy, or damage to the upper film due to undercutting. Therefore, the range of the film thickness is preferably 2000Å or less. For example, the range is 300 to 2000 Å, and more preferably 300 to 1800 Å. Here, the CD is a critical dimension, and is used as a meaning of a pattern line width in this specification.

In addition, in order to satisfy these conditions, the refractive index of the representative wavelength (for example, h-ray) included in the light of the translucent film material is preferably 1.5 to 2.9. More preferably, it is 1.8 to 2.4.

Furthermore, in order to fully exert a phase shift effect, it is preferable that a pattern cross section (the surface to be etched) formed by wet etching is approximately perpendicular to the main surface of the transparent substrate.

In consideration of the above properties, the film material used as the translucent film may be a material containing at least one of Zr, Nb, Hf, Ta, Mo, Ti and Si, or an oxide or nitrogen containing these materials. A compound of nitrogen oxides, nitrides, carbides, or oxynitrides.

A low-light transmission film is formed on the translucent film of the photomask base. As a film formation method, well-known methods, such as a sputtering method, can be applied similarly to the case of a translucent film.

The low-light-transmitting film of the photomask substrate may be a light-shielding film that does not substantially transmit light that is exposed. Alternatively, it can be set to have a specific low transmittance for the representative wavelength of the exposed light. The light-transmitting film used in the manufacture of the photomask of the present invention has a transmittance T2 (%) lower than that of the translucent film T1 (%) for light having a representative wavelength in the wavelength range of i-ray to g-ray. ). T2 may also be substantially zero (0.01 or less).

On the other hand, when the low-light-transmitting film can transmit exposed light, it is required that the transmittance and phase shift of the low-light-transmitting film to the exposed light can reach the transmittance of the low-light-transmitting portion of the reticle And the amount of phase shift. Preferably, in a laminated state of the low-light-transmitting film and the above-mentioned semi-transmissive film, the transmittance T3 (%) of light having a wavelength representative of the exposed light is 0.01 <T3 <30, more preferably 0.01 <T3 ≦ 20 , And further, the amount of phase shift 3 is set to 90 (degrees) or less, and more preferably 60 (degrees) or less.

As the property of the low-light-transmittance film alone, it is preferable that it does not substantially transmit the light of the above-mentioned representative wavelength, or has a transmittance (T2 (%)) of less than 30 (%) (that is, 0 <T2 <30) , Phase shift amount ( 2) Approximately 180 degrees. About 180 degrees means 120 to 240 degrees. Phase difference 1 is preferably 150 to 210 (degrees), and more preferably 170 to 190 (degrees).

The material of the low-light-transmittance film of the photomask substrate may be Cr or a compound thereof (oxide, nitride, carbide, oxynitride, or oxynitride), or a material containing Mo, W, Ta, or Ti. A metal silicide, or a compound thereof. However, the material of the low-light-transmittance film of the photomask base is preferably a material that can be wet-etched like the semi-transparent film and has an etching selectivity with respect to the material of the semi-transparent film. That is, it is desirable that the low-light-transmitting film has resistance to the etchant of the semi-transparent film, and the semi-light-transmitting film has resistance to the etchant of the low-transmissive film.

A first photoresist film is coated on the low-light transmission film of the photomask base. The photomask of the present invention is preferably written by a laser writing device, so a photoresist suitable for the laser writing device is made. The first photoresist film may be a positive type or a negative type, and the following description is made using a positive type.

Next, as shown in FIG. 4 (b), the first photoresist film is engraved by using a engraving device using engraving data based on a transfer pattern (first engraving). Then, using the first resist pattern obtained by development as a mask, the low-light-transmittance film is wet-etched. Thereby, a region to be a low-light-transmitting portion is defined, and a region of an auxiliary pattern (a low-light-transmitting film pattern) surrounded by the low-light-transmitting portion is defined. As the etchant (wet etchant) for performing wet etching, a known one suitable for the composition of the low-light-transmitting film used can be used. For example, if it is a film containing Cr, cerium ammonium nitrate or the like can be used as a wet etchant.

Next, as shown in FIG. 4 (c), the first resist pattern is peeled.

Next, as shown in FIG. 4 (d), a second photoresist film is coated on the entire surface including the formed low-transmittance film pattern.

Then, as shown in FIG. 4 (e), the second photoresist film is subjected to the second writing to form a shape formed by development. Into a second resist pattern. The second resist pattern and the low-light-transmittance film pattern are used as a mask to perform wet etching of a semi-transparent film. By this etching (development), a region including a main pattern of the light-transmitting portion exposed by the transparent substrate is formed. Furthermore, the second resist pattern covers an area that becomes an auxiliary pattern and has an opening in an area that becomes a main pattern including a light-transmitting portion, and it is preferable that the edge of the low-light-transmitting film is exposed from the opening. The writing data of the second writing is fixed in advance. In this way, it is possible to absorb the misalignment that occurs between the first writing and the second writing, and prevent the CD accuracy of the transfer pattern from deteriorating. This is the effect of using the materials of the low-light-transmitting film and the semi-transparent film to etch selectivity to each other.

Furthermore, in the photomask of this aspect, a semi-transparent film and a low-transmissive film may also be formed of a material having no etching selectivity and common etching characteristics, and an etching stop film may be provided between the two films.

That is, by setting the second resist pattern at the time of the second writing in this way, when an isolated hole pattern is to be formed on the transferee, the patterning of the light-shielding film and the translucent film will not cause positional deviation Therefore, in the transfer pattern illustrated in FIG. 1, the centers of gravity of the main pattern and the auxiliary pattern can be accurately matched.

The wet etchant for the translucent film is appropriately selected according to the composition of the translucent film.

Next, as shown in FIG. 4 (f), the second resist pattern is peeled off to complete the photomask of the present invention shown in FIG.

In the manufacture of a photomask for a display device, when an optical film such as a light-shielding film formed on a transparent substrate is patterned, as the applied etching, there are dry etching and wet etching. Either can be used, and wet etching is particularly advantageous in the present invention. The reason is that the size of the photomask used for the display device is relatively large, and thus there are various sizes. When manufacturing such a photomask, if dry etching using a vacuum chamber is applied, low efficiency will occur in the size or manufacturing steps of the dry etching device.

However, there are problems associated with the application of wet etching when manufacturing such a photomask. Because wet etching has the property of isotropic etching, when a specific film is to be etched in the depth direction and dissolved, the etching is also performed in a direction perpendicular to the depth direction. For example, when a slit is formed by etching a translucent film having a film thickness F (nm), the opening of the resist pattern serving as an etching mask is reduced by only 2F (nm) than the required slit width (that is, F (nm) on one side), and the narrower the slit becomes, the more difficult it is to maintain the dimensional accuracy of the resist pattern opening. Therefore, it is more useful to set the width d of the auxiliary pattern to 1 (μm) or more, and preferably 1.3 (μm) or more.

Further, when the film thickness F (nm) is large, the amount of side etching also becomes large. Therefore, even if the film thickness is small, it is advantageous to use a film material having a phase shift amount of approximately 180 degrees. As a result, it is expected that The transflective film has a higher refractive index for this wavelength. Therefore, it is preferable to use a material having a refractive index of 1.5 to 2.9, preferably 1.8 to 2.4, for the above-mentioned representative wavelength to make a semi-transparent film.

In addition, as the photomask of the present invention shown in FIG. 1, in addition to the above-mentioned aspects, there are also those who exhibit the same optical effects by different layer configurations.

A second aspect of the present invention has a layer structure showing a cross section in FIG. 3 (b). The top plan view of this photomask is similar to the first aspect shown in FIG. 1, but the laminated structure is different when viewed in cross section. That is, in the low-light-transmitting portion shown in FIG. 3 (b), the stacking order of the low-light-transmitting film and the semi-light-transmitting film is reversed up and down, and the low-light-transmitting film is disposed on the substrate side.

In this case, the design of the pattern of the mask of the present invention or its parameters, and the optical effects produced by them are the same as those of the mask of the first aspect. As a design pattern, the application shown in FIG. 2 The same applies to the modification. In addition, the physical properties of the film material used may be the same.

However, in the mask of the second aspect, the manufacturing method is slightly different from the first aspect in the following aspects. Therefore, the film material used may not necessarily be the same as the first aspect.

For example, in the first aspect, as shown in FIG. 4 (a), a photomask base formed by laminating a semi-transmissive film and a low-light transmissive film is prepared, and the photolithography step is applied twice to manufacture a photomask. However, in the second aspect, it is necessary to prepare a photomask base having only a low-light-transmitting film on a transparent substrate.

Then, the low-light-transmitting film is etched to form a low-light-transmitting film pattern. Then, a semi-transparent film is formed on the entire surface of the substrate on which the low-transmittance film pattern is formed, and patterned. In this case, it is preferable to select a material that can be patterned by wet etching in the same manner as in the first aspect. However, in this aspect, the low-light-transmitting film and the semi-light-transmitting film do not necessarily have to be resistant to each other's etchant. That is, the two films can be etched even if they have no etching selectivity to each other. Therefore, with regard to the choice of material, the degree of freedom is higher than that of the first aspect.

Next, a third aspect of the photomask of the present invention will be described with reference to FIG. 3 (c). In this aspect, the top view pattern is also the same as that in FIG. 1, and the design of the pattern or its parameters, and the optical effects produced by them are the same as the mask of the first aspect, except for the following aspects. As a design pattern, the same applies to the modification shown in FIG. 2.

The third aspect of the mask shown in Fig. 3 (c) differs from the first and second aspects of the mask in that the phase shift amount of the translucent film to the light of the above-mentioned representative wavelength is not limited. At approximately 180 degrees, in association with this, in the main pattern portion, the transparent substrate is etched by a specific amount. That is, instead of exposing a part of the main surface of the transparent substrate as a material, the main pattern in this aspect is exposed by etching to form a specific amount of etched portions on the main surface. Further, the phase difference between the representative wavelengths in the wavelength range of the i-rays to the g-rays that pass through each other is adjusted to approximately 180 degrees between the auxiliary pattern on which the translucent film is formed and the main pattern on which the etched portion is formed. Similar to the masks of the first and second aspects, the low-light-transmitting portion may be a semi-transparent film laminated on the transparent substrate in order or in reverse order, and the transmittance of light representing the wavelength is T2 (%) The structure of low light transmission film.

In the first aspect or the second aspect, the material and film thickness of the translucent film must be satisfied at the same time. The condition of the transmittance T1 and the condition that the phase difference between the representative wavelength of the main pattern and the auxiliary pattern is approximately 180 degrees. However, in the mask of the third aspect, it has the following advantages: The condition of the transmittance T1 is determined with priority. The composition or thickness of the translucent film can be adjusted according to the etching amount of the main pattern.

In this respect, the amount of phase shift of the translucent film of the mask of this aspect with respect to the light having the above-mentioned representative wavelength may also be 90 degrees or less, or 60 degrees or less. It is only necessary to adjust in such a manner that the phase difference between the representative wavelengths of the main pattern and the auxiliary pattern becomes approximately 180 degrees based on the sum of the etching amount of the main pattern and the phase shift amount of the translucent film.

In the photomask of the third aspect, wet or dry etching is used when the transparent substrate is etched, but dry etching is more preferably applied. In the photomask of this aspect, an etching stopper film may be provided between the semi-transmissive film and the low-transmissive film.

For example, the following steps may be applied: preparing a photomask base formed by laminating a semi-transparent film and a low-transmissive film on a transparent substrate. First, the two films of the main pattern portion are etched away, and then the transparent substrate is etched and etched. . Secondly, the second light lithography step is used to etch and remove the low-light transmission film in the auxiliary pattern portion, thereby making it possible to manufacture a third aspect of the photomask. In this case, the film material may be the same as the first aspect.

Furthermore, in the same manner as the relationship between the first aspect and the second aspect described above, in the photomask of the third aspect, the stacking order of the semi-transmissive film and the low-transmittance film may be reversed up and down.

Next, a fourth aspect of the photomask of the present invention will be described with reference to FIG. 3 (d). In this state, the top view pattern is also shown in FIG. 1. The fourth aspect forms an etched portion on the transparent substrate of the main pattern portion in the same manner as the third aspect, but unlike the third aspect, a translucent film is not used, and the transparent substrate (a portion of the main surface) of the auxiliary pattern portion is not used. Exposed. In addition, by selecting the etching depth of the main pattern portion, as in the first to third aspects, the representative of the main pattern and the auxiliary pattern are respectively transmitted. The phase difference of the light of the wavelength becomes approximately 180 degrees.

In this fourth aspect, since there is no semi-transmissive film in the auxiliary pattern portion, the transmittance (T1) is 100 (%). In this case, it is possible to reduce the number of film formations, thereby achieving advantages such as an increase in production efficiency and a reduction in the probability of occurrence of defects, as compared with the third aspect.

In this case, apply T1 = 100 (%) to equation (2) and become

That is, 0.5 ≦ d ≦ 1.5‧‧‧ (2).

It is preferably d <W1.

In addition, the amount of phase shift of the low-light-transmitting film used in the fourth aspect of the mask to the light having the above-mentioned representative wavelength need not be approximately 180 degrees, and preferably 90 degrees or less. More preferably, it is 60 degrees or less.

In the mask of the fourth aspect, the design of the pattern shown in FIG. 1, parameters other than the special record, and the optical effects produced by them are also the same as those of the mask of the first aspect. The same applies to the aspect in which the modification shown in FIG. 2 can be applied. The film material used for the low-light-transmittance film or its physical properties may be the same as the first aspect. That is, the transmittance of the above-mentioned representative wavelength of the low-light-transmitting portion is T3 (%), but it may be configured to form a low-light-transmitting film having a transmittance of T2 (%) of the above-mentioned representative-wavelength light on a transparent substrate. That is, the case is T2 = T3.

In addition, the fifth aspect is obtained by inverting the cross-sectional structure of the main pattern and the auxiliary pattern in the fourth aspect (FIG. 3 (e)). The main pattern of the fifth aspect is that a part of the main surface of the transparent substrate is exposed, and the auxiliary pattern has an etched portion formed on the main surface of the transparent substrate. That is, instead of forming an etched portion on the transparent substrate in place of the main pattern portion, the phase difference between the above-mentioned representative wavelength light transmitted through the main pattern and the auxiliary pattern is set to approximately 180 degrees by etching the transparent substrate of the auxiliary pattern portion. In this case, of course, the pattern in the plan view or its optical effect is also the same as in the fourth aspect. Also, about its manufacturer There is no special difference in the method or the applied membrane material. Therefore, the low-light-transmitting portion of the fifth aspect is a low-light-transmitting film having a transmittance of light having a wavelength of T2 (%) formed on a transparent substrate.

The sixth aspect of the present invention shown in FIG. 3 (f) shows the structure adopted in the first to fifth aspects (in FIG. 3 (f), a mask of the first aspect is typically used (Sectional schematic diagram) The possibility of adding a light-shielding film pattern. When the low-light-transmittance film has a substantial transmittance, it is worth considering this aspect.

That is, the interference effect of anti-phase light is used near the main pattern and the auxiliary pattern. However, in a region far from the low-light transmission part of the main pattern and the auxiliary pattern, there is no need to transmit light through the low-light transmission film, but there is There is a risk that the amount of the residual film of the resist pattern formed on the object to be transferred is reduced. When the risk is to be eliminated, it is also useful to add a light-shielding film pattern in the area far from the low-light-transmitting portion of the main pattern and the auxiliary pattern to completely block light.

Therefore, in the present invention, as long as the effect is not impaired, the use of such a light-shielding film pattern is not hindered. In addition, the light-shielding film refers to a film that does not substantially transmit exposed light (light having a wavelength representative of the i-ray to g-ray range) and has an OD (optical density) of 2 or more. Examples of the material include those containing chromium (Cr) as a main component.

The present invention includes a method for manufacturing a display device. The method includes the steps of: exposing an exposure device to the photomask of the present invention; and transferring the transfer pattern on a transferee to form a hole pattern.

The manufacturing method of the display device of the present invention is to first prepare the photomask of the present invention described above. Next, an exposure device having a numerical aperture (NA) of 0.08 to 0.20 and having an exposure light source including at least one of i-rays, h-rays, and g-rays is used to expose the above-mentioned transfer pattern to the object to be transferred. A hole pattern having a diameter W2 of 3.0 μm or less, preferably 0.6 to 3.0 μm is formed thereon. Furthermore, the exposure light source of the exposure device preferably includes i rays, h rays, and g rays. For exposure, it is usually advantageous to apply equal exposure.

As an exposure machine used when transferring a pattern for transfer using the photomask of the present invention, the following method can be used to perform equal magnification projection exposure. That is, it is used as an exposure machine for LCD (liquid crystal display device) (or FPD (flat panel display), liquid crystal), and its composition is a numerical aperture (NA) of the optical system of 0.08 to 0.15 (coherence factor) (σ) is 0.4 to 0.9), and the light source having exposure includes at least one of i-ray, h-ray, and g-ray (also referred to as a wide-wavelength light source). However, it is a matter of course that the present invention can be applied to an exposure device with a numerical aperture NA of 0.10 to 0.20 to obtain the effects of the invention.

In addition, the light source of the exposure device used can also use deformed illumination (belt illumination, etc.), but even if it is non-deformed illumination, the excellent effects of the invention can be obtained.

The present invention uses a photomask base formed by laminating a semi-transmissive film and a low-transmissive film (and further a light-shielding film as needed) on a transparent substrate as the first to third aspects (and the sixth aspect to which it is applied). The material of the mask. Furthermore, a resist film is formed on the surface to manufacture a photomask.

The physical properties, film quality, and composition of the semi-transmissive film and the low-transmissive film are as described above.

That is, the translucent film of the above-mentioned mask base is preferably 30 to 80 (%) in transmittance T1 to a representative wavelength in a wavelength range of i rays to g rays. In addition, the translucent film is set to have a film thickness with a refractive index of 1.5 to 2.9 with respect to the representative wavelength, and a phase shift amount of approximately 180 degrees. Even if the film thickness of the semi-transparent film having such a refractive index is thin enough, it also has the required phase shift amount, so the wet etching time of the semi-transparent film can be shortened. As a result, it is possible to suppress side etching of the translucent film.

In addition, in all aspects of the photomask of the present invention, a photomask substrate having a low-light-transmittance film can be used for manufacturing.

The low-light-transmittance film may be one that does not substantially transmit light of the aforementioned representative wavelength or has a transmittance of less than 30%. In addition, the low-light-transmittance film is representative of the range of i rays to g rays. The phase shift amount of the wavelength is set to approximately 180 degrees in the masks of the first and second aspects, and the mask of the third, fourth, and fifth aspects is preferably set to 90 degrees or less, and more preferably 60. Degrees or less are sufficient.

[Example]

Regarding the three types of photomasks (Comparative Examples 1-1 and 1-2 and Example 1) shown in FIG. 5, the transfer performance was compared and evaluated by optical simulation. In other words, optical simulations were performed on three photomasks having a pattern for transferring a pattern of holes having a diameter of 2.0 μm on the transfer target body, and showing what kind of transfer performance is displayed when the exposure conditions are commonly set.

(Comparative Example 1-1)

As shown in FIG. 5, the photomask of Comparative Example 1-1 has a pattern of a so-called binary photomask including a light-shielding film pattern formed on a transparent substrate. In the mask of Comparative Example 1-1, the main pattern including the light-transmitting portion exposed by the transparent substrate was surrounded by the light-shielding portion. The diameter W1 (one side of the square) of the main pattern is 2.0 (μm).

(Comparative Example 1-2)

As shown in FIG. 5, the mask of Comparative Example 1-2 is a halftone type phase shift mask, which is obtained by setting the exposure light transmittance (for h rays) to 5% and the phase shift amount to half of 180 degrees The light-transmitting film is formed by patterning, and has a main pattern including a light-transmitting portion of a quadrangle having one side (diameter) (that is, W1) of 2.0 (μm).

(Example 1)

As shown in FIG. 5, the mask of Example 1 has the transfer pattern of the present invention. Here, the main pattern is a square with one side (diameter) (that is, W1) of 2.0 (μm), the auxiliary pattern is an octagonal band with a width d of 1.3 (μm), and the width of the main pattern center and the auxiliary pattern The distance P between the centers, that is, the pitch P is set to 4 (μm).

The auxiliary pattern is formed by forming a translucent film on a transparent substrate. Hooders. The transmissivity T1 of the exposed light (for h-rays) of the translucent film is 70 (%), and the phase shift amount is 180 degrees. In addition, the low-light-transmitting portion surrounding the main pattern and the auxiliary pattern includes a light-shielding film (OD> 2) that does not substantially transmit the light of exposure.

Regarding any of the comparative examples 1-1 and 1-2 and the photomask of Example 1, a diameter W2 of 2.0 μm was formed on the object to be transferred (W1 = W2, that is, formed on the object to be transferred) The hole diameter W2 is the same as the hole pattern (diameter W1 of the main pattern of the pattern for transfer of the photomask). The exposure conditions used in the simulation are as follows. That is, the exposure light is set to a wide wavelength including i rays, h rays, and g rays, and the intensity ratio is set to g rays: h rays: i rays = 1: 0.8: 1.

The NA of the optical system of the exposure device was 0.1, and the coherence factor σ was 0.5. The film thickness of the positive-type photoresist for obtaining the cross-sectional shape of the resist pattern formed on the object to be transferred was set to 1.5 μm.

The performance evaluation of each transfer pattern under the above conditions is shown in FIG. 5. A spatial image of the light intensity formed on the object to be transferred and a cross-sectional shape of the resist pattern formed thereby are shown in FIG. 6.

(Optical evaluation of photomask)

For example, when transferring a fine light-transmitting pattern with a small diameter, the spatial image formed by the exposed light after passing through the mask on the transferee, that is, the distribution of the transmitted light intensity curve must be good. Specifically, it is important that the slope of the peak of the transmitted light intensity is steep, showing a nearly vertical rise, and the absolute value of the light intensity of the peak is higher (when a secondary peak is formed around, the intensity relative to the secondary peak is relatively Ground is high enough) and so on.

When evaluating the optical performance of the photomask more quantitatively, the following indicators can be used.

(1) Depth of Focus (DOF)

This index is the size of the focal depth within a range of ± 10% from the target CD. If the value of DOF is high, it is not easy to be leveled by the transferred object (such as a panel substrate for a display device). Candid influence, can form a fine pattern reliably, and suppress CD (line width) deviation.

(2) MEEF (Mask Error Enhancement Factor)

This index is a numerical value indicating the ratio of the Mask CD error to the CD error of the pattern formed on the transferee. The lower the MEEF, the more the CD error of the pattern formed on the transferee can be reduced.

(3) Eop

Among the photomasks used in the manufacture of display devices, Eop is a particularly important evaluation item. It is the amount of light required for exposure in order to form the desired pattern size on the transferee. Due to the large size of the mask in the manufacture of display devices (for example, one side of the main surface is a square or rectangle of about 300 ~ 1400mm), if a mask with a lower Eop value is used, the speed of scanning exposure can be increased, thereby increasing production. effectiveness.

If the performance of each sample of the simulation object is evaluated based on the above, as shown in FIG. 5, the photomask of Example 1 is very superior to the comparative example in that the depth of focus (DOF) is expanded to 55 μm or more. Display stable transferability. This means that the value of MEEF is small, and it also means that the precision of the CD of fine patterns is high.

Furthermore, the value of Eop of the mask of Example 1 was very small. This case shows an advantage that the exposure time does not increase or can be shortened even when a large-area display device is manufactured in the case of the photomask of Example 1.

In addition, referring to the spatial image of the transmitted light intensity shown in FIG. 6, it can be seen that in the case of the photomask of Example 1, the main pattern can be made relative to the level (Eth) of the threshold value of the resist sensitivity. Increasing the peak of the part can also increase the slope of the peak sufficiently (close to the surface of the object to be transferred). This aspect is superior to Comparative Examples 1-1 and 1-2. Here, by increasing the light intensity of the light passing through the auxiliary pattern at the position of the main pattern, the increase in Eop and Reduced MEEF. Furthermore, in the photomask of Example 1, there are side peaks on both sides of the position of the transferred image of the main pattern, but since it is equal to or less than Eth, it does not affect the transfer of the main pattern.

In addition, a method of reducing the loss of the resist residual film due to the side peak will be described below.

The pattern of the pattern for transfer formed on the photomask was changed, and simulations were performed using samples shown in FIG. 7 (Comparative Example 2-1, Comparative Example 2-2, and Example 2. Here, each sample is a The diameter W1 of the main pattern is set to 2.5 (μm), which is different from the above-mentioned samples (Comparative Example 1-1, Comparative Example 1-2, and Example 1) in this respect.

(Comparative Example 2-1)

As shown in FIG. 7, the mask of Comparative Example 2-1 is a pattern of a so-called binary mask including a light-shielding film pattern formed on a transparent substrate. In the mask of Comparative Example 2-1, the main pattern including the light-transmitting portion exposed by the transparent substrate was surrounded by the light-shielding portion. The diameter W1 (one side of the square) of the main pattern is 2.5 (μm).

(Comparative Example 2-2)

As shown in FIG. 7, the mask of Comparative Example 2-1 is a halftone type phase shift mask, which is obtained by setting the exposure light transmittance (for h rays) to 5% and the phase shift amount to half of 180 degrees. The light-transmitting film is formed by patterning, and has a main pattern including a light-transmitting portion of a quadrangle having a diameter W1 (one side of a square) of the main pattern of 2.5 (μm).

(Example 2)

As shown in FIG. 7, the mask of Example 2 is a transfer pattern of the present invention. The main pattern of the mask of Example 2 is a square with a diameter W1 (one side of the square) of the main pattern of 2.5 (μm), and an auxiliary pattern is an octagonal strip with a width d of 1.3 (μm). The center of the main pattern and the auxiliary pattern The distance P between the width centers is set to 4 (μm). Here, the mask of the second embodiment also assumes the mask of the first aspect.

Using the photomasks of Comparative Example 2-1, Comparative Example 2-2, and Example 2, a hole pattern having a diameter of 2.0 μm was formed on the object to be transferred. That is, the mask deviation (β = W1-W2) of these masks is set to 0.5 (μm). The exposure conditions used in the simulations were the same as those of the photomasks of Comparative Examples 1-1 and 1-2 and Example 1 described above.

From the data shown in FIG. 7, it is clear that when the photomask of Example 2 is used, it exhibits excellent DOF and MEEF, and shows performance advantageous to Comparative Examples 2-1 and 2-2. In the photomask of Example 2, especially, the DOF was a value exceeding 35 μm.

In addition, referring to the spatial image of the transmitted light intensity shown in FIG. 8 and the cross-sectional shape of the resist pattern on the object to be transferred, the excellent characteristics of the sample of Example 2 will become clearer. As shown in FIG. 8, when the photomask of Example 2 is used, the peak corresponding to the main pattern is significantly higher than the side peaks formed on both sides, and almost no resist damage occurs.

From the above results, it is clear that in the case of the pattern transfer using the photomask of the present invention, the pattern for the transfer with the mask deviation β of about 0.5 (μm), specifically 0.2 to 1.0 (μm). In this way, an excellent transfer image can be obtained which is easier for practical use.

From the above, the excellent performance of the photomask of the present invention can be confirmed. In particular, if the mask of the present invention is used, a MEEF value of 2.5 or less can be obtained in a fine pattern of 2 μm or less, which is of great significance in the manufacture of display devices in the future.

The use of the photomask of the present invention is not particularly limited. The photomask of the present invention can be preferably used when manufacturing a display device including a liquid crystal display device or an EL display device.

According to the photomask of the present invention, it is possible to control the mutual interference of the light passing through the exposure of both the main pattern and the auxiliary pattern, reduce the zero-order light during the exposure, and relatively increase the ratio of the first-order light. Therefore, the spatial image of transmitted light can be greatly improved.

As an application that can obtain such an effect, it is often used for liquid crystal or EL in order to form It is advantageous to use the mask of the present invention with isolated hole patterns such as the contact holes of the device. As the type of pattern, in most cases, a dense pattern that arranges a plurality of patterns with a certain regularity and has an optical effect on each other, is isolated from a pattern that does not have such a regular arrangement around it. Patterns are called differently. The photomask of the present invention is preferably used when an isolated pattern is to be formed on a body to be transferred.

To the extent that the effects of the present invention are not impaired, an additional optical film or functional film may be used for the photomask of the present invention. For example, in order to prevent the light transmittance of the low-light-transmitting film from causing troubles in the inspection or the position detection of the photomask, a configuration may be adopted in which a light-shielding film is formed in a region other than the pattern for transfer. In addition, in the translucent film, an anti-reflection layer may be provided on the surface to reduce reflection of writing light or exposure light.

Claims (25)

A pattern transfer method, which uses a mask for manufacturing a display device having a pattern for transfer on a transparent substrate, and transfers the pattern for transfer to a transferee, and the pattern for transfer is an isolated hole pattern formation The pattern used has: a main pattern with a diameter of W1 (μm); an auxiliary pattern with a width of d (μm), which is arranged near the main pattern; and a light-shielding part, which constitutes the main pattern and the auxiliary pattern, Area; the auxiliary pattern surrounds the main pattern around the light-shielding portion, and is in the shape of a regular polygonal or circular band; light of a representative wavelength in a wavelength range of i rays to g rays passing through the main pattern and The phase difference of the light representing the wavelength passing through the auxiliary pattern is 150 to 210 degrees, using a numerical aperture (NA) of 0.08 to 0.20, and having an exposure light source including at least one of i rays, h rays, and g rays The exposure device transfers the transfer pattern onto the transferee; and during the transfer, the amount of exposure light Eop required to form the isolated hole pattern of the target size on the transferee is less than Having a transfer pattern of the auxiliary pattern. For example, the pattern transfer method of item 1, wherein the diameter W1 of the above main pattern satisfies the following formula (1): 0.8 ≦ W1 ≦ 4.0‧‧ For example, the pattern transfer method of item 1, wherein the diameter W1 of the above main pattern satisfies the following formula (1) -1: 1.0 ≦ W1 ≦ 3.0‧‧‧ 1. The pattern transfer method according to any one of claims 1 to 3, which uses an exposure device having an exposure light source including i rays, h rays, and g rays to transfer the transfer pattern onto the transfer target . The pattern transfer method according to any one of claims 1 to 3, which uses the above-mentioned exposure device and exposes the above-mentioned pattern for transfer by non-deformation lighting. The pattern transfer method according to any one of claims 1 to 3, wherein when the transmittance of light of the above-mentioned representative wavelength transmitted through the auxiliary pattern is set to T1 (%), the width d (μm) of the auxiliary pattern satisfies the following Formula (2): The pattern transfer method of any one of claims 1 to 3, wherein when the distance between the center of the main pattern and the center of the auxiliary pattern in the width direction is set to P (μm), the following formula (3) is satisfied: 1.0 <P ≦ 5.0 ‧ ‧ The pattern transfer method according to any one of claims 1 to 3, wherein the auxiliary pattern is formed on the transparent substrate by forming a translucent film having a transmittance of T1 (%) to light of the representative wavelength. For example, the pattern transfer method of item 8, wherein the transmissivity T1 (%) of the translucent film satisfies the following formula (5): 30 ≦ T1 ≦ 80‧‧‧ (5). The pattern transfer method of claim 9, wherein the translucent film includes a material containing at least one of zirconium, niobium, hafnium, tantalum, molybdenum, and titanium and silicon, or an oxide, nitride, or Nitrogen oxide, carbide, or oxynitride material. The pattern transfer method according to any one of claims 1 to 3, wherein the width d of the auxiliary pattern is 1 (μm) or more. According to the pattern transfer method of claim 8, wherein the main pattern is formed by exposing a part of the main surface of the transparent substrate, the auxiliary pattern is formed by forming the translucent film on the transparent substrate, and the light-shielding portion is formed by The semi-transparent film and the light-shielding film are laminated on the transparent substrate in order or in reverse order. The pattern transfer method according to claim 8, wherein the main pattern is formed by forming an etched portion on the main surface of the transparent substrate, the auxiliary pattern is formed by forming the translucent film on the transparent substrate, and the light-shielding portion It is formed by laminating the semi-transparent film and the light-shielding film on the transparent substrate in order or in the reverse order. The pattern transfer method according to claim 1, wherein the auxiliary pattern is formed by exposing the transparent substrate. According to the pattern transfer method of claim 14, wherein the main pattern is formed by forming an etched portion on the main surface of the transparent substrate, the auxiliary pattern is formed by exposing a part of the main surface of the transparent substrate, and the light-shielding portion is formed by A light-shielding film is formed on the transparent substrate. According to the pattern transfer method of claim 14, wherein the main pattern is formed by exposing a part of the main surface of the transparent substrate, the auxiliary pattern is formed by forming an etched portion on the main surface of the transparent substrate, and the light-shielding portion is formed by A light-shielding film is formed on the transparent substrate. According to the pattern transfer method of any one of claims 1 to 3, a hole pattern having a transfer diameter W2 of 3.0 (μm) or less (where W1> W2) is formed on the object to be transferred corresponding to the main pattern described above. By. The pattern transfer method according to claim 17, wherein when the difference W1-W2 between the diameter W1 of the main pattern and the transfer diameter W2 on the transferee is set as a deviation β (μm), 0.2 ≦ β ≦ 1.0‧‧‧ (6). The pattern transfer method according to any one of claims 1 to 3, wherein the auxiliary pattern has a shape of a regular polygonal band. The pattern transfer method according to claim 19, wherein the auxiliary pattern has a shape of a regular octagonal band. According to the pattern transfer method of any one of claims 1 to 3, in the above-mentioned transfer, compared with the case of using a transfer pattern without the above-mentioned auxiliary pattern, the mask error enhancement factor MEEF value is smaller. The pattern transfer method according to any one of claims 1 to 3, wherein one side of the main surface of the photomask is a square or a rectangle of 300 to 1400 mm. A method for manufacturing a display device includes the pattern transfer method according to any one of claims 1 to 22. A photomask, which is a photomask for the manufacture of a display device with a pattern for transfer on a transparent substrate, for forming an isolated hole pattern on a person to be transferred; the transfer pattern is a pattern for forming an isolated hole pattern, And has: a main pattern with a diameter of W1 (μm); an auxiliary pattern with a width of d (μm), which is arranged near the main pattern; and a light-shielding part, which constitutes an area other than the main pattern and the auxiliary pattern; The auxiliary pattern surrounds the main pattern through the light-shielding part, and is in the shape of a regular polygonal band or a circular band; light of a representative wavelength in a wavelength range of i rays to g rays passing through the main pattern and transmits the auxiliary pattern. The phase difference of the light of the aforementioned representative wavelength is 150 to 210 degrees, which is used for an exposure light source having a numerical aperture (NA) of 0.08 to 0.20 and having at least one of i rays, h rays, and g rays. The exposure device is a photomask for exposure; and the amount of exposure light Eop required to form the isolated hole pattern of the target size on the transferee is smaller than the transfer pattern without the auxiliary pattern. For example, the mask of claim 24, wherein the above-mentioned transfer pattern has a smaller mask error enhancement factor MEEF value than the case of using a transfer pattern without the above-mentioned auxiliary pattern.