KR20200132813A - Photomask and method for manufacturing display device - Google Patents

Abstract

The present invention relates to a photomask suitable for the light exposure environment of a mask for manufacturing a display device and capable of transferring a fine pattern stably, and a method for manufacturing the same. The photomask is provided with a pattern for transfer formed on a transparent substrate, wherein the pattern for transfer has a main pattern having a diameter of W1 (micrometer), a supplementary pattern disposed near the main pattern and having a width of d (micrometer) and a low-transmission portion disposed in a region other than the region where the main pattern and the supplementary pattern are formed; the phase difference between the representative wavelength transmitting the main pattern and the representative wavelength transmitting the supplementary pattern is about 180 degrees; and diameter W1, wavelength d, transmission T1 (%) of the supplementary pattern, transmission T3 (%) of the low-transmission portion and interval P (micrometer) between the center of the main pattern and the center of the supplementary pattern in the width direction have a predetermined relationship.

Description

A photomask and a method of manufacturing a display device TECHNICAL FIELD [PHOTOMASK AND METHOD FOR MANUFACTURING DISPLAY DEVICE]

TECHNICAL FIELD The present invention relates to a photomask, which is represented by liquid crystal or organic EL, advantageously used in manufacturing a display device, and a method for manufacturing a display device using the photomask.

In Patent Document 1, as a photomask used in the manufacture of a semiconductor device, four auxiliary light-transmitting parts are arranged parallel to each side of the main light-transmitting part (hole pattern), and the light phase of the main light-transmitting part and the auxiliary light-transmitting part is reversed. One phase shift mask is described.

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

Japanese Patent Laid-Open No. Hei 3-15845 Japanese Patent Publication No. 2013-148892

Currently, in a display device including a liquid crystal display device, an EL display device, and the like, it is desired to be brighter and to reduce power and to improve display performance such as high-precision, high-speed display, and wide viewing angle.

For example, speaking of a thin film transistor ("TFT") used in the display device, a contact hole formed in the interlayer insulating film among a plurality of patterns constituting the TFT connects the upper and lower patterns reliably. Correct operation is not guaranteed if it does not have the action to cause. On the other hand, in order to maximize the aperture ratio of the display device and make it a bright, power-saving display device, the diameter of the contact hole is required to be sufficiently small. Along with this, the diameter of a hole pattern provided in a photomask for forming such a contact hole is also desired to be 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, and in the near future, it is considered that formation of a pattern having a diameter of 1.5 µm or less is also desired. Due to such a background, there is a need for a display device manufacturing technology capable of reliably transferring minute contact holes.

However, in the field of a photomask for manufacturing a semiconductor device (LSI) in which the degree of integration is higher than that of a display device, and the pattern has been remarkably refined, in order to obtain high resolution, a high NA (Numerical Aperture) (for example, 0.2 or more) was applied and the exposure light was shortened, and excimer lasers of KrF or ArF (single wavelengths of 248 nm and 193 nm, respectively) were widely used.

On the other hand, in the field of lithography for manufacturing a display device, it is not common for the above-described method to be applied to improve resolution. Rather, the NA of an exposure apparatus known as a liquid crystal display (LCD) or the like is about 0.08 to 0.10, and the exposure light source also uses a broad wavelength region including i-line, h-line, and g-line. However, there has been a tendency to value production efficiency and cost rather than resolution or depth of focus.

However, even in manufacturing a display device as described above, the request for miniaturization of patterns is increasing unprecedentedly. Here, there are several problems in applying the technology for manufacturing a semiconductor device as it is to manufacturing a display device. For example, a large investment is required to switch to a high-resolution exposure apparatus having a high NA (number of apertures), and a match with the price of the display apparatus cannot be obtained. Alternatively, for changing the exposure wavelength (a short wavelength such as an ArF excimer laser is used as a single wavelength), it is difficult to apply it to a display device having a large area, and if it is applied, for example, production efficiency decreases. It is unsuitable in that it requires significant investment.

In addition, as will be described later, a photomask for a display device has manufacturing restrictions and various unique problems different from a photomask for manufacturing a semiconductor device.

From the above circumstances, it is practically difficult to convert the photomask of Patent Document 1 as it is for manufacturing a display device. In addition, although there is a description that the halftone phase shift mask described in Patent Document 2 has an improved light intensity distribution compared to a binary mask, there is further room for performance improvement.

Therefore, in a method for manufacturing a display device using a mask for manufacturing a display device, it has been desired to overcome the above problems and stably transfer onto a transfer object as a fine pattern. Accordingly, an object of the present invention is to obtain an excellent photomask that is advantageously suitable for an exposure environment of a mask for manufacturing a display device and capable of stably transferring a fine pattern, and a method for manufacturing the same.

In order to solve the said subject, this invention has the following structure. The present invention is a method of manufacturing a photomask having the following configurations 1 to 14, and a display device having the following configuration 15.

(Configuration 1)

Configuration 1 of the present invention is a photomask having a transfer pattern formed on a transparent substrate, wherein the transfer pattern has a main pattern having a diameter of W1 (µm) and a width d ( Μm), a representative wavelength in a wavelength range of i-line to g-line transmitting the main pattern and a low-transmitting portion disposed in a region other than the main pattern and the auxiliary pattern, and the auxiliary pattern The phase difference with the representative wavelength that transmits is approximately 180 degrees, the light transmittance of the representative wavelength that transmits through the auxiliary pattern is T1 (%), and the light transmittance of the representative wavelength that transmits the low-transmitting part is T3 ( %), and when the distance between the center of the main pattern and the center in the width direction of the auxiliary pattern is P (µm), the following equations 1 to 4 are satisfied.

[Equation 1]

[Equation 2]

[Equation 3]

[Equation 4]

(Configuration 2)

In configuration 2 of the present invention, the auxiliary pattern is the photomask according to configuration 1, wherein a semi-transmissive film having a transmittance of T1 (%) for light of the representative wavelength is formed on the transparent substrate. .

(Configuration 3)

Configuration 3 of the present invention is the photomask described in Configuration 2, wherein the transmittance T1 (%) of the semi-transmissive film satisfies the following equation (5).

[Equation 5]

(Configuration 4)

Configuration 4 of the present invention is the photomask according to configuration 2 or 3, wherein the auxiliary pattern has a width d of 1 (µm) or more.

(Configuration 5)

In the configuration 5 of the present invention, the main pattern is made by exposing a part of the main surface of the transparent substrate, the auxiliary pattern is made by forming the semi-transmissive film on the transparent substrate, and the low-transmitting portion , On the transparent substrate, the semi-transmissive film and the low-transmissive film having a light transmittance of T2 (%) of the representative wavelength are stacked in this order or in the reverse order. It is the photomask according to any one of to 4.

(Configuration 6)

In the configuration 6 of the present invention, the main pattern is formed by forming a recess on the main surface of the transparent substrate, the auxiliary pattern is formed by forming the semi-transmissive film on the transparent substrate, and the low transmissive portion , On the transparent substrate, the semi-transmissive film and the low-transmissive film having a light transmittance of T2 (%) of the representative wavelength are stacked in this order or in the reverse order. It is the photomask according to any one of to 4.

(Configuration 7)

In the configuration 7 of the present invention, the semi-transmissive film is a material containing at least one of Zr, Nb, Hf, Ta, Mo, and Ti and Si, or an oxide, nitride, oxynitride, carbide, or oxidation of these materials. It is a photomask according to any one of configurations 2 to 6, which is made of a material containing nitride carbide.

(Configuration 8)

In the configuration 8 of the present invention, the auxiliary pattern is the photomask according to the configuration 1, wherein the transparent substrate is exposed.

(Configuration 9)

In the configuration 9 of the present invention, the main pattern is formed by forming a recess in the main surface of the transparent substrate, the auxiliary pattern is made by exposing a part of the main surface of the transparent substrate, and the low light transmitting part, It is the photomask described in the substrate in Configuration 8, wherein a low-transmissive film having a light transmittance of T3 (%) of the representative wavelength is formed on the transparent substrate.

(Configuration 10)

In the configuration 10 of the present invention, the main pattern is made by exposing a part of the main surface of the transparent substrate, the auxiliary pattern is made by forming a recess in the main surface of the transparent substrate, and the low light transmitting part, It is the photomask described in the substrate in Configuration 8, wherein a low-transmissive film having a light transmittance of T3 (%) of the representative wavelength is formed on the transparent substrate.

(Composition 11)

In the configuration 11 of the present invention, a hole pattern having a transfer diameter W2 of 3.0 (µm) or less (only W1>W2) is formed on the object to be transferred, corresponding to the main pattern. It is the photomask in any one of 10.

(Composition 12)

In the configuration 12 of the present invention, when the difference W1-W2 between the diameter W1 of the main pattern and the transfer diameter W2 on the object to be transferred is a bias β (µm),

[Equation 6]

It is a photomask according to Configuration 11, characterized in that it is.

(Configuration 13)

In the configuration 13 of the present invention, the transmittance T3 (%) for light of the representative wavelength in the low-transmitting portion is,

[Equation 7]

It is a photomask according to any one of configurations 1 to 12, characterized in that it satisfies.

(Configuration 14)

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

(Configuration 15)

Configuration 15 of the present invention is a step of preparing the photomask according to any one of configurations 1 to 14, and exposure including at least one of i-line, h-line and g-line with a numerical aperture (NA) of 0.08 to 0.20 It is a method of manufacturing a display device including a step of exposing the transfer pattern to light using an exposure apparatus having a light source, and forming a hole pattern having a diameter W2 of 0.6 to 3.0 (µm) on a transfer object.

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

1 is a schematic plan view of an example of a photomask of the present invention.
2 is a schematic plan view (a) to (f) of another example of the photomask of the present invention.
3 is an example (a) to (f) of the layer structure of the photomask of the present invention.
4 is a schematic cross-sectional view and a schematic plan view showing an example of a manufacturing process for 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, showing dimensions, and transfer performance by optical simulation.
6 is a diagram illustrating a spatial image of light intensity formed on an object to be transferred and (b) a cross-sectional shape of a resist pattern formed therefrom when the photomasks of Comparative Examples 1-1 and 1-2 and Example 1 are used. It is a figure showing.
Fig. 7 is a schematic plan view of the photomasks of Comparative Examples 2-1 and 2-2 and Example 2, showing dimensions and transfer performance by optical simulation.
FIG. 8 is a cross-sectional view of (a) a spatial image of light intensity formed on a transfer object and (b) a cross-sectional shape of a resist pattern formed therefrom when the photomasks of Comparative Examples 2-1 and 2-2 and Example 2 were used. It is a figure showing.

When the CD (Critical Dimension, hereinafter used as the pattern line width) of the transfer pattern possessed by the photomask is micronized, the process of accurately transferring it to the object to be transferred (also referred to as the object to be processed, such as a thin film to be etched) is performed. It becomes more difficult. The resolution limit indicated as a specification in an exposure apparatus for a display device is about 2 to 3 µm in most cases. On the other hand, among the transfer patterns to be formed, those having dimensions that are close to or less than this have already appeared. Further, since the mask for manufacturing a display device has a larger area compared to the mask for manufacturing a semiconductor device, in actual production, it is very difficult to uniformly transfer a transfer pattern having a CD of less than 3 µm in-plane.

Therefore, by devising factors other than pure resolution (by the exposure wavelength and the numerical aperture of the exposure optical system), it is necessary to draw out effective transfer performance.

In addition, since the area of the object to be transferred (flat panel display substrate) is large, it can be said that in the step of pattern transfer by exposure, defocus is likely to occur due to the flatness of the surface of the object to be transferred. Under this environment, it is very meaningful to sufficiently secure a focus margin (DOF) during exposure.

In addition, a photomask for manufacturing a display device has a large size as well-known, and in the wet treatment (development or wet etching) in the photomask manufacturing process, uniformity of CD (line width) at various positions within the surface It is not easy to secure. In order to accommodate the final CD accuracy within the specified allowable range, it is essential to ensure a sufficient depth of focus (DOF) in the exposure process, and it is desirable that other performances do not deteriorate with this.

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

As shown in Fig. 1, the transfer pattern formed on the transparent substrate includes a main pattern having a diameter W1 (µm) and an auxiliary pattern having a width d (µm) disposed in the vicinity of the main pattern. Further, in regions other than the main pattern and the auxiliary pattern, a low-transmitting portion is formed.

Here, the transmittance of light having a representative wavelength in the i-line to g-line wavelength region that passes through the auxiliary pattern is T1, and the transmittance of the light of the representative wavelength that passes through the low-transmitting portion is T3. Further, 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). At this time, the photomask of the present invention satisfies the following relationship.

[Equation 1]

[Equation 2]

[Equation 3]

[Equation 4]

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

Incidentally, the light transmittances T1 and T3 referred to herein are based on the transmittance of the transparent substrate, and are determined by the layer structure of the corresponding portion.

A schematic cross-sectional view of such a transfer pattern can be, for example, as shown in Fig. 3A. This is referred to as the first form of the photomask of the present invention, and will be described with reference to FIG. 3A.

In this embodiment, the main pattern includes a light-transmitting portion to which the transparent substrate is exposed. Further, a film having a high transmittance may be formed on the main pattern. However, from the viewpoint of obtaining the maximum transmittance, it is preferable that a film having a high transmittance is not formed on the main pattern and the transparent substrate is exposed.

Further, the auxiliary pattern of this embodiment includes a semi-transmissive portion in which a semi-transmissive film is formed on a transparent substrate. This semi-transmissive film has a phase shift amount that shifts light of a representative wavelength in the wavelength range of i-line to g-line by approximately 180 degrees, and has a transmittance T1 (%) for a representative wavelength. Further, a portion surrounding the main pattern and the auxiliary pattern is a low-transmitting portion in which at least a low-transmitting film is formed on a transparent substrate. That is, in the transfer pattern shown in Fig. 1, regions other than the regions in which the main pattern and the auxiliary pattern are formed are the low-transmitting portions. As shown in Fig. 3A, in this embodiment, a semi-transmissive film and a low-transmissive film are laminated on a transparent substrate in the low-transmissive portion. Further, the low-transmitting portion may be laminated on the transparent substrate, a semi-transmissive film and a low-transmitting film having a light transmittance of T2 (%) of a representative wavelength, in this order or in the opposite order.

The low-transmitting portion of the photomask of the present invention has a predetermined low transmittance with respect to a representative wavelength of exposure light. That is, with respect to light having a representative wavelength in the wavelength range of the i-line to g-line, the low-transmitting portion has a transmittance T3 (%) lower than the transmittance T1 (%) of the auxiliary pattern including the semi-transmitting portion. Therefore, in this embodiment (Fig. 3(a)) in which the low-transmissive portion is formed by lamination of the semi-transmissive portion and the low-transmissive portion, the lamination,

T3<T1

Thus, by selecting the transmittance T2 (%) of the low-transmitting film, the transmittance T3 (%) of the low-transmitting portion may be adjusted.

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

Specifically, W1 (㎛), the following equation (1)

[Equation 1]

It is desirable to have a relationship of. At this time, the diameter W2 (µm) of the main pattern (hole pattern) formed on the transfer object is 3.0 (µm) or less, specifically,

0.6≤W2≤3.0

You can do it.

Further, the photomask of the present invention 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 is 3.0 (µm) or less, the effect of the present invention is more remarkably obtained. Preferably, the diameter W1 (㎛) of the main pattern,

1.0≤W1≤3.0

You can do it. In addition, although the relationship between the diameter W1 and the diameter W2 may be set to W1=W2, preferably W1>W2. That is, when β (㎛) is used as the bias value,

β=W1-W2>0(㎛)

when,

0.2≤β≤1.0

More preferably,

0.2≤β≤0.8

You can do it with In this case, as will be described later, advantageous effects such as reducing the loss of the resist pattern on the object to be transferred are obtained.

In the above, the diameter W1 of the main pattern means the diameter of a circle or a numerical value that is approximated thereto. For example, when the shape of a main pattern is a regular polygon, the diameter W1 of a main pattern is made into the diameter of an inscribed circle. If the shape of the main pattern is square as shown in Fig. 1, the diameter W1 of the main pattern is the length of one side. The same applies to the diameter W2 of the transferred main pattern in terms of the diameter of a circle or a numerical value approximating it.

Of course, when you want to form a finer pattern, it is possible to make W1 less than 2.5 (㎛), or less than 2.0 (㎛), and furthermore, it is also possible to apply the present invention with W1 less than 1.5 (㎛). have.

In addition, the above preferable ranges for setting the diameter W1 of the main pattern in the photomask of the present invention, the diameter W2 of the main pattern on the object to be transferred, and the bias are the photos of the present invention according to the following second to sixth aspects. Also in a mask, it can apply similarly.

The phase difference φ between the main pattern and the auxiliary pattern is approximately 180 degrees with respect to the representative wavelength of the exposure light used in the photomask exposure of the present invention having such a transfer pattern. That is, the phase difference φ1 between the light of the representative wavelength transmitted through the main pattern and the representative wavelength transmitted through the auxiliary pattern is approximately 180 degrees. By about 180 degrees, it means 120 to 240 degrees. Preferably, the phase difference φ1 is 150 to 210 degrees, more preferably 170 to 190 degrees.

In addition, since the photomask of the present invention has a remarkable effect when using exposure light including i-line, h-line, or g-line, exposure light including at least one of i-line, h-line, and g-line can be used. have. In particular, it is preferable to apply broad wavelength light including i-line, h-line and g-line as exposure light. In this case, as a representative wavelength, it can be set to any one of i-line, h-line, and g-line. For example, the photomask of the present invention can be configured using the h-line as a representative wavelength.

In order to form such a phase difference, the main pattern is a translucent portion formed by exposing the main surface of a transparent substrate, and the auxiliary pattern is a translucent portion formed by forming a translucent film on a transparent substrate. The amount of phase shift with respect to the wavelength may be approximately 180 degrees.

In addition, the preferred range of the phase difference between the main pattern and the auxiliary pattern and the wavelength of exposure light applied to the photomask of the present invention is the same also in the photomask of the present invention according to the following second to sixth aspects.

In the photomask of the first aspect, that is, the photomask shown in Fig. 3A, the light transmittance T1 of the semi-transmissive portion can be set as follows. That is, when the transmittance of the semitransmissive film formed on the semitransmissive portion with respect to the representative wavelength is T1 (%),

30≤T1≤80

To do. More preferably,

40≤T1≤75

to be. In addition, the transmittance T1 (%) is taken as the transmittance of the representative wavelength, based on the transmittance of the transparent substrate.

In the photomask of the present invention, the low-transmitting portion disposed in a region other than where the main pattern and the auxiliary pattern are formed, and formed around the main pattern and the auxiliary pattern can be configured as follows.

The low-transmitting portion may be one that does not substantially transmit exposure light (light having a representative wavelength in a wavelength range of i-line to g-line). In this case, a low-transmissive film alone may be used that does not substantially transmit the representative wavelength (i.e., a light-shielding film), and a low-transmitting film having an optical density of OD≥2 may be applied, or a low-transmissive film and a semi-transmissive film As a laminated film, a substantial light-shielding film (optical concentration OD≥2) may be used.

Alternatively, the low light-transmitting portion may transmit exposure light in a predetermined range. However, in the case of transmitting exposure light in a predetermined range, the transmittance of the low-transmitting portion T3 (%) (here, in the case of laminating a semi-transmissive film and a low-transmitting film, the transmittance of the laminated film),

T3<T1

Is to meet. Preferably,

0.01<T3<30

More preferably,

0.01<T3≤20

Meets. The transmittance T3 (%) is also referred to as the transmittance of the representative wavelength, based on the transmittance of the transparent substrate.

In addition, in the case where the low-transmitting portion transmits exposure light with a predetermined transmittance, the phase difference φ3 between the transmitted light of the low-transmitting portion and the transmitted light of the light-transmitting portion is preferably 90 degrees or less, and more preferably 60 degrees or less. to be. When "90 degrees or less" is expressed in radians, it means that the phase difference is "(2n-1/2)π to (2n+1/2)π (where n is an integer)." As above, it is calculated as a phase difference with respect to a representative wavelength included in the exposure light.

Therefore, in this case, as the sole property of the low-transmissive film used in the photomask of this embodiment, it has a transmittance [T2 (%)] of less than 30 (%) (that is, 0 <T2 <30), and a phase shift amount ( It is preferable that φ2) is approximately 180 degrees. By about 180 degrees, it means 120 to 240 degrees. Preferably, the phase difference φ1 is 150 to 210 degrees, more preferably 170 to 190 degrees. Thereby, about the phase shift characteristic of the low light-transmitting part including lamination, phi 3 can be made into the above-mentioned range.

The transmittance here is also referred to as the transmittance of the representative wavelength, based on the transmittance of the transparent substrate, similarly to the above.

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

[Equation 2]

When is established, excellent effects of the invention are obtained. That is, when √(T1/100)×d is within the above range, the amount of light transmitted through the auxiliary pattern interacts with that of the main pattern in a good balance, 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 a pitch P (µm), and the pitch P is,

1.0<P≤5.0

It is desirable that the relationship of

More preferably, the pitch P is,

1.5<P≤4.5

You can do it with

In the present invention, the auxiliary pattern has an effect of pseudologically exerting an optical action such as a dense pattern on the isolated main pattern by design, but when the above relational expression is satisfied, the main pattern and the auxiliary pattern The exposure light that has transmitted through can exhibit a good interaction with each other, and can exhibit excellent transferability, as shown in Examples to be described later.

The width d (µm) of the auxiliary pattern is a dimension less than or equal to the resolution limit in the exposure conditions (exposure apparatus used) applied to the photomask of the present invention, and as a specific example,

d≥0.7

More preferably,

d≥0.8

More preferably, the width d (µm) of the auxiliary pattern is 1 (µm) or more.

Moreover, it is preferable that d<=W1, and it is more preferable that d<W1.

Further, more preferably, the relational expression of Equation 2 is the following Equation 2-1, and still more preferably, the following Equation 2-2.

[Equation 2-1]

[Equation 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 a shape that is rotationally symmetric, including an octagon or a circle. In addition, the center of rotational symmetry may be used as the reference center 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 thereto. It is preferable that the shape of the auxiliary pattern is the shape of the object to be rotated three times symmetrical or more with respect to the center of the hole pattern and given a constant width. Preferred shapes of the main pattern and the auxiliary pattern are the shapes illustrated in Fig. 2 (a) to (f), and the design of the main pattern and the design of the auxiliary pattern are different from each other in Fig. 2 (a) to (f). You may combine them.

For example, the case where the outer periphery of the auxiliary pattern is a regular polygon (preferably a 2n square, where n is an integer of 2 or more) or a circle such as a square, a regular hexagon, a regular octagon, and a regular decagon is illustrated. And, as the shape of the auxiliary pattern, it is preferable that the outer periphery and the inner periphery of the auxiliary pattern are substantially parallel, that is, a shape such as a regular polygonal or circular band having a substantially constant width. This strip-shaped shape is also called a polygonal strip or a circular strip. As the shape of the auxiliary pattern, it is preferable that such a regular polygonal strip or circular strip is a shape surrounding the periphery of the main pattern. At this time, since the balance of the amount of light between the transmitted light of the main pattern and the transmitted light of the auxiliary pattern can be made substantially equal, it is easy to obtain a light interaction for obtaining the effect of the present invention.

In particular, when the photomask of the present invention is used as a photomask for manufacturing a display device, that is, when the photomask of the present invention is used in combination with a photoresist for manufacturing a display device, it corresponds to an auxiliary pattern on a transfer object. It is possible to reduce the resist loss of the portion.

Alternatively, the shape of the auxiliary pattern may be a shape in which a part of the polygonal band or circular band is omitted without completely surrounding the main pattern. The shape of the auxiliary pattern may be, for example, a shape in which the corner portions of the rectangular band are missing, as shown in Fig. 2(f).

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

An example of a method for manufacturing the photomask of this embodiment will be described below with reference to FIG. 4.

As shown in Fig. 4A, a photomask blank is prepared.

In this photomask blank, a semi-transmissive film and a low-transmissive film are formed in this order on a transparent substrate made of glass or the like, and a first photoresist film is applied thereto.

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

It is preferable that the semi-transmissive film is made of a material that satisfies the above transmittance and phase difference, and is capable of wet etching, as described below. However, if the amount of side etching that occurs during wet etching is too large, problems such as deterioration of CD accuracy and destruction of the upper layer film due to undercut may occur. Therefore, the range of the film thickness is preferably 2000 angstroms or less. For example, in the range of 300 to 2000 Å, more preferably 300 to 1800 Å. Here, CD is Critical Dimension, and in this specification, it is used as the meaning of the pattern line width.

In addition, in order to satisfy these conditions, it is preferable that the semi-transmissive film material has a refractive index of 1.5 to 2.9 at a representative wavelength (eg, h-line) included in the exposure light. More preferably, they are 1.8 to 2.4.

In addition, in order to sufficiently exhibit the phase shift effect, it is preferable that the pattern cross-section (etched surface) by wet etching is close to perpendicular to the main surface of the transparent substrate.

In consideration of the above properties, as the film material of the semi-transmissive film, a material containing at least one of Zr, Nb, Hf, Ta, Mo, Ti and Si, or an oxide, nitride, oxynitride, carbide, or oxidation of these materials. It can be made of a material containing nitride carbide.

On the semi-transmissive film of the photomask blank, a low-transmissive film is formed. As the film formation method, as in the case of a semi-transmissive film, a known means such as a sputtering method can be applied.

The low-transmitting film of the photomask blank may be a light-shielding film that does not substantially transmit exposure light. Alternatively, it can be set to have a predetermined low transmittance with respect to the representative wavelength of exposure light. The low-transmissive film used in the manufacture of the photomask of the present invention has a transmittance T2 (%) lower than the transmittance T1 (%) of the semi-transmissive film for light of a representative wavelength in the i-line to g-line wavelength range. T2 may be substantially zero (0.01 or less).

On the other hand, when the low-transmissive film can transmit exposure light, the transmittance and phase shift amount of the low-transmitting film with respect to the exposure light can achieve the transmittance and phase shift amount of the low-transmitting portion of the photomask of the present invention. Is required. Preferably, in a stacked state of the low-transmissive film and the semi-transmissive film, the transmittance T3 (%) for light of a representative wavelength of exposure light is 0.01<T3<30, preferably 0.01<T3≦20, and , The phase shift amount φ3 is set to 90 (degrees) or less, more preferably 60 (degrees) or less.

As a single property of the low-transmissive film, it does not substantially transmit light of the representative wavelength, or has a transmittance [T2 (%)] of less than 30 (%) (that is, 0 <T2 <30), and It is preferable that the shift amount φ2 is approximately 180 degrees. By about 180 degrees, it means 120 to 240 degrees. Preferably, the phase difference φ1 is 150 to 210 (degrees), more preferably 170 to 190 (degrees).

The material of the low-transmissive film of the photomask blank may be Cr or a compound thereof (oxide, nitride, carbide, oxynitride, or oxynitride carbide), or silicide of a metal containing Mo, W, Ta, and Ti, or, It may be the said compound of the silicide. However, the material of the low-transmissive film of the photomask blank can be wet etched like the semi-transmissive film, and a material having etching selectivity to the material of the semi-transmissive film is preferable. That is, it is preferable that the low-transmissive film has resistance to the etchant of the semi-transmissive film, and the semi-transmissive film has resistance to the etchant of the low-transmissive film.

On the low-transmissive film of the photomask blank, a first photoresist film is further applied. Since the photomask of the present invention is preferably drawn by a laser drawing device, a suitable photoresist is used. The first photoresist film may be of a positive type or a negative type, but it will be described below as a positive type.

Next, as shown in Fig. 4B, a drawing device is used for the first photoresist film, and drawing using drawing data based on the transfer pattern is performed (first drawing). Then, using the first resist pattern obtained by development as a mask, the low-transmissive film is wet etched. Thereby, an area to be a low light-transmitting portion is defined, and an area of the auxiliary pattern (low light-transmitting film pattern) surrounded by the low light-transmitting portion is defined. As the etching solution (wet etchant) for wet etching, a known one suitable for the composition of the low transmissive film to be used can be used. For example, if it is a film containing Cr, cerium nitrate ammonium etc. can be used as a wet etchant.

Next, as shown in Fig. 4C, the first resist pattern is removed.

Next, as shown in Fig. 4D, a second photoresist film is applied to the entire surface including the formed low-transmissive film pattern.

Next, as shown in Fig. 4E, second drawing is performed on the second photoresist film, and a second resist pattern formed by development is formed. Using this second resist pattern and the low-transmissive film pattern as masks, wet etching of the semi-transmissive film is performed. By this etching (development), a region of the main pattern including the light transmitting portion to which the transparent substrate is exposed is formed. In addition, the second resist pattern covers a region serving as an auxiliary pattern and has an opening in a region serving as a main pattern including a light-transmitting portion, and the edge of the low-transmissive film is exposed from the opening. It is advisable to size the data. By doing in this way, it is possible to absorb the alignment misalignment occurring between the first drawing and the second drawing, and to prevent deterioration of the CD accuracy of the transfer pattern. This is an effect of using the etching selectivity for each of the materials of the low-transmissive film and the semi-transmissive film.

Further, in the photomask of the present embodiment, the semi-transmissive film and the low-transmissive film may be formed of a material having no etching selectivity and having common etching characteristics, and an etching stopper film may be formed between the two films.

That is, by performing the sizing of the second resist pattern at the time of the second drawing as described above, when an isolated hole pattern is to be formed on a transfer object, a positional shift does not occur in the patterning between the light-shielding film and the semi-transmissive film. In the transfer pattern as exemplified in, the center of gravity of the main pattern and the auxiliary pattern can be precisely and precisely matched.

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

Next, as shown in Fig. 4(f), the second resist pattern is peeled off, and the photomask of the present invention shown in Fig. 1 is completed.

In manufacturing a photomask for a display device, when patterning an optical film such as a light-shielding film formed on a transparent substrate, there are dry etching and wet etching as applied etching. Although any may be employed, wet etching is particularly advantageous in the present invention. This is because a photomask for a display device has a relatively large size, and there are many types of sizes. In manufacturing such a photomask, if dry etching using a vacuum chamber is applied, inefficiency occurs in the size and manufacturing process of the dry etching apparatus.

However, there is also a problem associated with applying wet etching at the time of manufacturing such a photomask. Since wet etching has the property of isotropic etching, when a predetermined film is etched in the depth direction and eluted, the etching proceeds in a direction perpendicular to the depth direction. For example, when forming a slit by etching a semi-transmissive film having a thickness of F (nm), the opening of the resist pattern serving as the etching mask is 2F (nm) [that is, one side F (nm)] than the desired slit width. Although it is small, it is difficult to maintain the dimensional accuracy of the resist pattern opening as the slit has a fine width. For this reason, it is useful that the width d of the auxiliary pattern is 1 (µm) or more, preferably 1.3 (µm) or more.

In addition, when the film thickness F (nm) is large, the amount of side etching is also large, so it is advantageous to use a film material having a phase shift amount of approximately 180 degrees even if the film thickness is small. It is desired that the light-transmitting film has a high refractive index. For this reason, it is preferable to use a material such as 1.5 to 2.9, preferably 1.8 to 2.4 with respect to the representative wavelength, to form a semi-transmissive film.

By the way, as the photomask of the present invention shown in Fig. 1, there is a photomask that exhibits the same optical effect by other layer configurations in addition to the above form.

The second aspect of the present invention has a layered configuration showing a cross section in Fig. 3B. The schematic plan view of this photomask is as shown in Fig. 1 as in the first embodiment, but the laminated structure when viewed from the cross section is different. That is, in the low-transmissive portion shown in Fig. 3B, the stacking order of the low-transmitting film and the semi-transmitting film is reversed up and down, and the low-transmitting film is disposed on the substrate side.

In this case, as the photomask of the present invention, the design of the pattern, its parameters, and optical effects thereof are the same as those of the photomask of the first form, and the modified example shown in FIG. 2 can be applied as the design design. It is also the same. In addition, the physical properties of the membrane material to be used can be the same.

However, in the photomask of the second form, there is a slight difference from the first form in the following points in terms of the manufacturing method, and for this reason, even in the film material used, it is not necessarily the same as the first form. .

For example, in the first aspect, as shown in Fig. 4A, a photomask blank in which a semi-transmissive film and a low-transmissive film are stacked is prepared, and a photolithography process is applied twice to the photomask blank. Although the mask was produced, in the second aspect, it is necessary to prepare a photomask blank in which only a low-transmissive film is formed on a transparent substrate.

And this low-transmissive film is etched first, and a low-transmitting film pattern is formed. Subsequently, a semi-transmissive film is formed on the entire surface of the substrate on which the low-transmissive film pattern is formed, and patterned. In this case, as in the first aspect, it is preferable to select a material capable of patterning by wet etching. However, in this embodiment, it is not essential that the low-transmissive film and the semi-transmissive film have resistance to mutual etchant. That is, etching can be performed even if both films do not have etching selectivity. Therefore, regarding the selection of the material, the degree of freedom is higher than that of the first form.

Next, a third aspect of the photomask of the present invention will be described with reference to Fig. 3C. Also in this form, the schematic plan view is the same as that of FIG. 1, and the design of the pattern, its parameters, and the optical effect of them are the same as those of the photomask of the first form, except for the following points, As a design design, it is also the same that the modified example shown in FIG. 2 is applicable.

The difference between the photomask of the third form shown in Fig. 3C from the photomasks of the first and second forms is that the semi-transmissive film has a phase shift amount of about 180 degrees for light of the representative wavelength. It is a point that is not restricted, and in this regard, in the main pattern portion, a predetermined amount of the transparent substrate is dug. That is, in the main pattern of this form, instead of exposing a part of the main surface of the transparent substrate as a material, the recessed surface in which a predetermined amount of recesses is formed by etching is exposed on the main surface. In addition, between the auxiliary pattern in which the semi-transmissive layer is formed and the main pattern in which the recess is formed, the phase difference of the representative wavelengths in the wavelength range of the i-line to g-line that transmits each other is adjusted to approximately 180 degrees. Like the photomasks of the first and second forms, the low-transmissive portion is on the transparent substrate, the semi-transmissive film, and the low-transmissive film having a light transmittance of T2 (%) of a representative wavelength, in this order or vice versa. It may be a structure stacked with.

In the first form or the second form, it is necessary to satisfy both the condition of the transmittance T1 and the condition that the phase difference between the representative wavelength transmitted through the main pattern and the auxiliary pattern is approximately 180 degrees, depending on the material and film thickness of the semitransmissive film. However, in the photomask of the third aspect, there is an advantage that the condition of the transmittance T1 is preferentially determined the composition and the film thickness of the semi-transmissive film, and the phase difference can be adjusted by the amount of depression of the main pattern.

From this point of view, in the photomask of this embodiment, the amount of phase shift with respect to light of the representative wavelength of the semi-transmissive film may be 90 degrees or less, or 60 degrees or less. By the sum of the amount of depression of the main pattern and the amount of phase shift of the semi-transmissive film, the phase difference between the representative wavelengths that pass through the main pattern and the auxiliary pattern may be adjusted to be approximately 180 degrees.

In addition, in the photomask of the third aspect, wet or dry etching is used to form a recess in the transparent substrate, but dry etching is more preferably applied. Further, also in the photomask of this embodiment, an etching stopper film may be formed between the semi-transmissive film and the low-transmissive film.

For example, a photomask blank in which a semi-transmissive film and a low-transmissive film are stacked on a transparent substrate is prepared, first, both films of the main pattern are removed by etching, and then, a process of etching the transparent substrate is applied. I can. Next, by etching and removing the low-transmissive film in the auxiliary pattern portion by a second photolithography process, a photomask of the third aspect can be manufactured. In this case, as a film material, it can be performed similarly to 1st form.

Further, similarly to the relationship between the first and second modes, in the photomask of the third embodiment, the stacking order of the semi-transmissive film and the low-transmissive film may be reversed up and down.

Next, a fourth embodiment of the photomask of the present invention will be described with reference to Fig. 3D. Also in this form, the schematic plan view is as shown in FIG. In the fourth form, as in the third form, a recess is formed in the transparent substrate of the main pattern part, but unlike the third form, a semi-transmissive film is not used, and the transparent substrate (a part of the main surface) of the auxiliary pattern part is It is exposed. And, by selecting the depth of the depression of the main pattern portion, the optical phase difference of the representative wavelength transmitted through the main pattern and the auxiliary pattern, respectively, as in the first to third embodiments, is approximately 180 degrees.

In this fourth aspect, since the semi-transmissive film does not exist in the auxiliary pattern portion, the transmittance T1 is 100 (%). In this case, the number of times of film formation can be reduced, thereby obtaining advantages such as an improvement in production efficiency and a decrease in the probability of occurrence of defects from the third aspect.

In this case, T1 = 100 (%) is applied to Equation 2,

[Equation 2]

In other words,

0.5≤d≤1.5

Becomes. Preferably, d<W1.

In addition, the amount of phase shift for light of the representative wavelength, which the low-transmissive film used for the photomask of the fourth aspect, does not have to be approximately 180 degrees, and is preferably 90 degrees or less. More preferably, it is 60 degrees or less.

In the photomask of the fourth aspect, the design of the pattern shown in FIG. 1, parameters other than those specified, and optical effects thereof are the same as those of the photomask of the first aspect, and as a design design, FIG. It is also the same that the modified example shown in 2 is applicable. In addition, the film material used for the low-transmissive film and its physical properties can be the same as in the first embodiment. That is, in the low-transmitting portion, the transmittance of the representative wavelength is T3 (%), but this can be a structure in which a low-transmissive film having a light transmittance of the representative wavelength of T2 (%) is formed on a transparent substrate. That is, in the case of T2=T3.

By the way, it is the 5th aspect [FIG. 3(e)] that reversed the cross-sectional structure of the main pattern and the auxiliary pattern in 4th aspect. In the main pattern of the fifth aspect, a part of the main surface of the transparent substrate is exposed, and in the auxiliary pattern, a recess is formed in the main surface of the transparent substrate. That is, by digging the transparent substrate in the auxiliary pattern portion in response to the change in formation of the hollow substrate in the main pattern portion, the optical retardation of the representative wavelength transmitted through the main pattern and the auxiliary pattern is approximately 180 degrees. In this case as well, it goes without saying that the plan view design and its optical effect are the same as those of the fourth aspect. In addition, there is no particular difference in the manufacturing method or film material to be applied. Therefore, in the low-transmitting portion of the fifth aspect, a low-transmitting film having a light transmittance of T2 (%) at a representative wavelength is formed on the transparent substrate.

The sixth aspect of the present invention shown in (f) of FIG. 3 is a schematic cross-sectional view of a photomask of the first aspect with respect to the configuration employed in the first to fifth aspects (represented in FIG. 3 (f)). Is used], indicating the possibility of adding a light-shielding film pattern. This is worth considering when the low transmissive film has a substantial transmittance.

That is, in the vicinity of the main pattern and the auxiliary pattern, the interference effect of the light of the reverse phase is used, but in the region of the low-transmitting portion spaced apart from the above, the presence of light passing through the low-transmitting film is unnecessary, or rather, it is formed on the object. There is a risk of causing a disadvantage of reducing the amount of remaining film of the resist pattern. In the case of attempting to exclude this risk, it is also useful to completely shield light by adding a light shielding film pattern in the region of the low light-transmitting portion spaced apart from the main pattern and the auxiliary pattern.

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

The present invention includes a method for manufacturing a display device including the step of exposing the photomask of the present invention to the above-described photomask of the present invention with an exposure device, transferring the transfer pattern onto a transfer object, and forming a hole pattern. do.

In the method of manufacturing a display device of the present invention, first, the photomask of the present invention described above is prepared. Next, using an exposure apparatus having an exposure light source having a numerical aperture (NA) of 0.08 to 0.20 and including at least one of i-line, h-line and g-line, the transfer pattern is exposed, and the transfer pattern is , To form a hole pattern having a diameter W2 of 3.0 μm or less, preferably 0.6 to 3.0 μm. In addition, it is preferable that the exposure light source of the exposure apparatus includes i-line, h-line and g-line. For exposure, it is common and advantageous to apply equal exposure.

As an exposure machine used when transferring a transfer pattern using the photomask of the present invention, it is a method of performing equal-fold projection exposure, and the following are mentioned. That is, it is an exposure machine used as an LCD (liquid crystal display) (or FPD, liquid crystal), and its configuration has an optical system numerical aperture (NA) of 0.08 to 0.15 (coherence factor (σ) of 0.4 to 0.9) And a light source (also referred to as a broad wavelength light source) including at least one of i-line, h-line, and g-line in exposure light. However, even in an exposure apparatus having a numerical aperture NA of 0.10 to 0.20, it is of course possible to obtain the effects of the invention by applying the present invention.

Further, the light source of the exposure apparatus to be used may be a modified illumination (eg, annular illumination), but even if it is a non-deformed illumination, excellent effects of the invention can be obtained.

The present invention is a photomask blank in which a semi-transmissive film and a low-transmissive film (and, if necessary, a light-shielding film) are stacked on a transparent substrate as a raw material for a photomask of the first to third forms (and the sixth form to which the same is applied). Use. Further, a resist film is applied and 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, it is preferable that the translucent film of the photomask blank has a transmittance T1 of 30 to 80 (%) for a representative wavelength in a wavelength range of i-line to g-line. Further, the translucent film has a refractive index of 1.5 to 2.9 with respect to the representative wavelength, and has a film thickness having a phase shift amount of approximately 180 degrees. Even if the film thickness of the semi-transmissive film having such a refractive index is sufficiently thin, it has a desired amount of phase shift, so that the wet etching time of the semi-transmissive film can be shortened. As a result, side etching of the semitransmissive film can be suppressed.

In addition, in all aspects of the photomask of the present invention, it can be manufactured using a photomask blank having a low-transmissive film formed thereon.

As for this low-transmissive film, one that does not substantially transmit light of the representative wavelength or has a transmittance of less than 30% can be used. In addition, the amount of phase shift with respect to the representative wavelength within the range of i-line to g-line of the low light-transmitting film is approximately 180 degrees in the photomasks of the first and second forms, and the photoresist according to the third, fourth, and fifth forms. In the mask, 90 degrees or less, more preferably 60 degrees or less may be used.

[Example]

About three types of photomasks shown in FIG. 5 (Comparative Examples 1-1 and 1-2 and Example 1), the transfer performance was compared and evaluated by optical simulation. That is, for three photomasks having a transfer pattern for forming a hole pattern having a diameter of 2.0 µm on a transfer object, an optical simulation is performed on what transfer performance is exhibited when exposure conditions are set in common. Did.

(Comparative Example 1-1)

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

(Comparative Example 1-2)

As shown in Fig. 5, the photomask of Comparative Example 1-2 was formed by patterning a semi-transmissive film having an exposure light transmittance (pair h line) of 5% and a phase shift amount of 180 degrees, and one side (diameter) (that is, W1 ) Is a halftone type phase shift mask having a main pattern including a square light-transmitting portion of 2.0 (µm).

(Example 1)

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

The auxiliary pattern is assumed to be a photomask of the first form, in which a semi-transmissive film is formed on a transparent substrate. The exposure light (versus h line) transmittance T1 of this semitransmissive film is 70 (%), and the amount of phase shift is 180 degrees. In addition, the low-transmitting portion surrounding the main pattern and the auxiliary pattern is made of a light-shielding film (OD>2) that does not substantially transmit exposure light.

In either of the photomasks of Comparative Examples 1-1 and 1-2 and Example 1, the diameter W2 on the object to be transferred is 2.0 µm (W1 = W2. That is, the diameter W2 formed on the object to be transferred is a photo) It is assumed that a hole pattern that is the same as the diameter W1 of the main pattern of the transfer pattern of the mask) is formed. The exposure conditions applied by simulation are as follows. That is, the exposure light was set to a broad wavelength including i-line, h-line, and g-line, and the intensity ratio was set to g-line:h-line:i-line = 1:0.8:1.

The optical system of the exposure apparatus has an NA of 0.1 and a coherence factor σ of 0.5. The film thickness of the positive photoresist formed on the transfer object to obtain the cross-sectional shape of the resist pattern was 1.5 µm.

Under the above conditions, the performance evaluation of each transfer pattern is shown in FIG. In addition, FIG. 6 shows a spatial image of light intensity formed on the transfer object and a cross-sectional shape of a resist pattern formed thereby.

(Optical evaluation of photomask)

For example, in order to transfer a fine light-transmitting pattern having a small diameter, the exposure light after transmission of the photomask must have a good spatial image formed on the object to be transferred, that is, the profile of the transmitted light intensity curve. Specifically, the slope forming the peak of the transmitted light intensity is sharp, the upward direction is close to the vertical, and the absolute value of the peak light intensity is high (if a sub-peak is formed around it, the intensity is Relatively, high enough), etc. are important.

More quantitatively, when evaluating the photomask from optical performance, the following indicators can be used.

(1) Depth of focus (DOF)

For the target CD, the amount of depth of focus to be in the range of ±10%. When the DOF value is high, it is difficult to be affected by the flatness of the object to be transferred (for example, a panel substrate for a display device), so that a fine pattern can be reliably formed, and the CD (line width) variation is suppressed.

(2) MEEF (Mask Error Enhancement Factor)

It is a value indicating the ratio of the mask CD error and the CD error of the pattern formed on the object to be transferred. The lower the MEEF, the less the CD error of the pattern formed on the object to be transferred.

(3) Eop

In a photomask for manufacturing a display device, Eop is a particularly important evaluation item. This is the amount of exposure light required to form a desired pattern size on a transfer object. In the manufacture of display devices, since the photomask size is large (for example, a square or rectangle with a main surface of about 300 to 1400 mm per side), it is possible to speed up the scan exposure by using a photomask with a low Eop value. Thus, production efficiency is improved.

Based on the above, when the performance of each sample to be simulated is evaluated, as shown in Fig. 5, the photomask of Example 1 has a depth of focus (DOF) that is enlarged to 55 µm or more. In comparison, it is a very excellent point, and shows stable transferability of the pattern. This means that the MEEF value is small and the CD accuracy of a fine pattern is high.

Also, the value of the photomask Eop of Example 1 is very small. In the case of the photomask of Example 1, this has an advantage in that the exposure time does not increase or can be shortened even in manufacturing a large-area display device.

In addition, referring to the spatial image of the transmitted light intensity shown in FIG. 6, in the case of the photomask of Example 1, it is possible to increase the peak of the main pattern portion with respect to the level (Eth) which becomes the threshold value at which the resist absorbs light. And, it can be seen that the slope of the peak can be sufficiently erected (close to perpendicular to the surface of the object to be transferred). This point is superior compared with Comparative Examples 1-1 and 1-2. Here, by using the light passing through the auxiliary pattern to enhance the light intensity at the position of the main pattern, an increase in Eop and a decrease in MEEF are achieved. In addition, in the photomask of Example 1, side peaks are generated on both sides of the transfer image position of the main pattern, but since Eth or less, transfer of the main pattern is not affected.

In addition, a method of reducing the loss of the resist residual film resulting from this side peak will be described below.

The design of the transfer pattern formed on the photomask was changed, and simulation was performed using the samples of Comparative Example 2-1, Comparative Example 2-2, and Example 2 shown in FIG. 7. Here, each of the samples is different from the above samples (Comparative Example 1-1, Comparative Example 1-2 and Example 1) in that the diameter W1 of the main pattern is 2.5 (µm).

(Comparative Example 2-1)

As shown in Fig. 7, the photomask 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 photomask of Comparative Example 2-1, the main pattern including the light-transmitting portion to which the transparent substrate is exposed is surrounded by the light-shielding portion. The diameter W1 (one side of a square) of this main pattern is 2.5 (µm).

(Comparative Example 2-2)

As shown in Fig. 7, the photomask of Comparative Example 2-1 is formed by patterning a semi-transmissive film having an exposure light transmittance of 5% and a phase shift amount of 180 degrees, and the diameter W1 of the main pattern (square One side) is a halftone type phase shift mask having a main pattern including a square light-transmitting portion of 2.5 (µm).

(Example 2)

As shown in Fig. 7, the photomask of Example 2 is a transfer pattern of the present invention. The main pattern of the photomask of Example 2 is a square with a diameter W1 (one side of the square) of 2.5 (㎛) of the main pattern, and the auxiliary pattern is an octagonal band with a width d of 1.3 (㎛), and the center of the main pattern , The pitch P, which is the distance between the width center of the auxiliary pattern, was 4 (µm). Here too, the photomask of Example 2 assumes a photomask of the first form.

It is assumed that a hole pattern having a diameter of 2.0 µm is formed on the object to be transferred using the photomasks of Comparative Example 2-1, Comparative Example 2-2, and Example 2. That is, the mask bias (β = W1-W2) of these photomasks was set to 0.5 (µm). The exposure conditions applied by simulation are the same as those of Comparative Examples 1-1 and 1-2 and the photomasks of Example 1 described above.

As apparent from the data shown in Fig. 7, when the photomask of Example 2 was used, advantageous performance was exhibited for Comparative Examples 2-1 and 2-2, along with excellent DOF and MEEF. In the photomask of Example 2, in particular, the DOF has a value exceeding 35 µm.

Further, 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 become apparent. 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 resist damage hardly occurs.

From the above results, in the case of pattern transfer using the photomask of the present invention, the mask bias β is about 0.5 (µm), specifically, in a transfer pattern in the range of 0.2 to 1.0 (µm), it is more practical. It has become clear that easy-to-follow, excellent transfer images can be obtained.

From the above, the excellent performance of the photomask of the present invention was confirmed. Particularly, when the photomask of the present invention is used, the 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 future display device manufacturing.

There is no particular limitation on the use of the photomask of the present invention. The photomask of the present invention can be preferably used when manufacturing a display device including a liquid crystal display device, an EL display device, or the like.

According to the photomask of the present invention, it is possible to control the mutual interference of exposure light passing through both the main pattern and the auxiliary pattern, to reduce the zero-shielding light during exposure, and to increase the ratio of the ±1 order light relatively. For this reason, the spatial image of transmitted light can be improved significantly.

As a use in which such an operation and effect can be advantageously obtained, it is advantageous to use the photomask of the present invention for forming an isolated hole pattern such as a contact hole that is widely used in a liquid crystal or EL device. As a type of pattern, by arranging a number of patterns with a certain regularity, they are called dense patterns that exert an optical influence on each other, and isolated patterns that do not exist around them. There are many cases. The photomask of the present invention is preferably applied when it is desired to form an isolated pattern on a transfer object.

As long as 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 problem that the light transmittance of the low-transmissive film interferes with inspection or position detection of a photomask, a light-shielding film may be formed in a region other than the transfer pattern. In addition, in the semitransmissive film, an antireflection layer for reducing reflection of drawing light or exposure light may be formed on the surface thereof.

Claims (14)

For manufacturing a display device in which a semi-transmissive film having a transmittance T1 of 30 to 80 (%) for a representative wavelength of exposure light and a low-transmissive film having a transmittance of the representative wavelength smaller than that of the semi-transmitting film are stacked on the main surface of a transparent substrate As a photomask blank,
The semi-transmissive film is a film capable of wet etching, has a refractive index of 1.5 to 2.9 for the representative wavelength, and has a film thickness having a phase shift amount of 150 to 210 degrees,
The low-transmissive film is capable of wet etching, and the optical density OD is 2 or more,
A photomask blank for manufacturing a display device, characterized in that an etching stopper film is provided between the semi-transmissive film and the low-transmissive film. For manufacturing a display device in which a semi-transmissive film having a transmittance T1 of 30 to 80 (%) for a representative wavelength of exposure light and a low-transmissive film having a transmittance of the representative wavelength smaller than that of the semi-transmitting film are stacked on the main surface of a transparent substrate As a photomask blank,
The semi-transmissive film is a film capable of wet etching, has a refractive index of 1.5 to 2.9 for the representative wavelength, and has a film thickness having a phase shift amount of 150 to 210 degrees,
The low-transmissive film can be wet etched, and the low-transmissive film and the semi-transmissive film are stacked, and the transmittance T3 (%) for light of the representative wavelength is T3≦20, and a phase shift amount

3 is less than 90 degrees,
A photomask blank for manufacturing a display device, characterized in that an etching stopper film is provided between the semi-transmissive film and the low-transmissive film. The method according to claim 1 or 2,
The photomask blank for manufacturing a display device, wherein the low-transmitting film is an oxide, nitride, carbide, oxynitride, or oxynitride carbide of Cr or Cr. The method according to claim 1 or 2,
The semi-transmissive film is characterized in that it is made of a material containing at least one of Zr, Nb, Hf, Ta, Mo, and Ti and Si, or a material containing an oxide, nitride, oxynitride, carbide, or oxynitride carbide thereof. , Photomask blanks for manufacturing display devices. The method according to claim 1 or 2,
The photomask blank for manufacturing a display device, wherein the low-transmitting film and the thin-transmitting film are made of a material having a common etching property. The method according to claim 1 or 2,
The photomask blank for manufacturing a display device, wherein the exposure light includes i-line, h-line, or g-line. A photomask for manufacturing a display device having a transfer pattern by patterning the semi-transmissive film and the low-transmissive film in the photomask blank for manufacturing a display device according to claim 1 or 2, respectively,
The transcription pattern,
A main pattern having a diameter W1 (µm) comprising a light transmitting portion to which the transparent substrate is exposed,
An auxiliary pattern having a width d (µm) formed of a semi-transmissive portion disposed near the main pattern and having the semi-transmissive film formed on the transparent substrate, and
It is disposed in a region of the transfer pattern other than where the main pattern and the auxiliary pattern are formed, and has a low-transmitting portion in which at least the low-transmitting film is formed on the transparent substrate,
The light transmitting part is formed by exposing the transparent substrate,
The semi-transmissive part is formed by forming the semi-transmissive film on the transparent substrate,
The low transmissive portion is formed by stacking the semi-transmissive layer and the low transmissive layer on the transparent substrate,
Characterized in that it satisfies the following equations (1) and (2),

···(One)

···(2)
Photomask for manufacturing display devices. The method of claim 7,
A photomask for manufacturing a display device, wherein the width d of the auxiliary pattern satisfies d≦W1. The method of claim 7,
While the diameter W1 of the main pattern in the transfer pattern is 4.0 (µm) or less, a hole pattern having a diameter W2 (however, W1> W2) is formed on the transfer object corresponding to the main pattern. That is, a photomask for manufacturing a display device. The method of claim 9,
A photomask for manufacturing a display device, wherein the diameter W2 is 3.0 (µm) or less. The method of claim 9,
A photomask for manufacturing a display device, wherein a difference W1-W2 between the diameter W1 of the main pattern and the diameter W2 on the transfer object is a bias β (µm), and is 0.2≦β≦1.0. As a manufacturing method of a photomask for manufacturing a display device,
A step of preparing the photomask blank for manufacturing a display device according to claim 1 or 2, and
And forming a transfer pattern by wet etching the low-transmissive film and the semi-transmissive film, respectively,
The low-transmissive film has a transmittance T2 (%) lower than the transmittance T1 (%) of the semi-transmissive film with respect to the light of the representative wavelength,
The transcription pattern,
A main pattern having a diameter W1 (µm) comprising a light transmitting portion to which the transparent substrate is exposed,
An auxiliary pattern having a width d (µm) formed of a semi-transmissive portion disposed near the main pattern and having the semi-transmissive film formed on the transparent substrate, and
It is disposed in a region of the transfer pattern other than where the main pattern and the auxiliary pattern are formed, and has a low-transmitting portion in which at least the low-transmitting film is formed on the transparent substrate,
The light transmitting part is formed by exposing the transparent substrate,
The semi-transmissive part is formed by forming the semi-transmissive film on the transparent substrate,
The low transmissive portion is formed by stacking the semi-transmissive layer and the low transmissive layer on the transparent substrate,
Characterized in that it satisfies the following equations (1) and (2),

···(One)

···(2)
A method of manufacturing a photomask for manufacturing a display device. A method of manufacturing a display device comprising a step of preparing the photomask according to claim 7, and a step of exposing the transfer pattern to light using an exposure device to form a hole pattern on a transfer object. A display device comprising a step of preparing a photomask for manufacturing a display device by the manufacturing method according to claim 12, and a step of exposing the transfer pattern using an exposure device to form a hole pattern on a transfer object. Manufacturing method.

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