KR102304206B1 - Photomask and method for manufacturing display device - Google Patents

Abstract

The present invention is advantageously suited to the exposure environment of a mask for manufacturing a display device and can provide an excellent photomask capable of stably transferring a fine pattern and a method for manufacturing the same. A photomask comprising a transfer pattern formed on a transparent substrate, the transfer pattern comprising: a main pattern having a diameter of W1 (µm); an auxiliary pattern having a width of d (µm) arranged in the vicinity of the main pattern; a low light-transmitting portion disposed in a region other than where the main pattern and the auxiliary pattern are formed, the phase difference between the representative wavelengths passing through the main pattern and the auxiliary pattern is approximately 180 degrees; The transmittance T1 (%) of , 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 are in a predetermined relationship.

Description

A method for manufacturing a photomask and a display device

BACKGROUND OF THE INVENTION Field of the Invention [0001] The present invention relates to a photomask advantageously used for production of a display device represented by liquid crystal or organic EL, and a method for manufacturing a display device using the same.

In Patent Document 1, as a photomask used for manufacturing a semiconductor device, four auxiliary light transmitting portions are arranged parallel to each side of the main light transmitting portion (hole pattern) so that the optical phases of the main light transmitting portion and the auxiliary light transmitting portion are reversed. One phase shift mask is described.

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

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

Currently, in a display device including a liquid crystal display device, an EL display device, or the like, improvement in display performance such as a high-definition, high-speed display and a wide viewing angle is desired while being brighter and more power-saving.

For example, in the case of a thin film transistor (“TFT”) used in the display device, a contact hole formed in an interlayer insulating film among a plurality of patterns constituting the TFT reliably connects the upper and lower layers of the pattern. Correct operation is not guaranteed if it does not have a triggering action. On the other hand, in order to maximize the aperture ratio of the display device to provide a bright and power-saving display device, it is required that the diameter of the contact hole is sufficiently small. In connection with this, the diameter of the hole pattern with which the photomask for forming such a contact hole is also miniaturized (for example, less than 3 micrometers) is desired. For example, it is considered that a hole pattern having a diameter of 2.5 µm or less, and further, a hole pattern having a diameter of 2.0 µm or less is required, and formation of a pattern having a diameter of 1.5 µm or less less than this is also desired in the near future. In view of such a background, there is a need for a manufacturing technology for a display device capable of reliably transferring minute contact holes.

By the way, in the field of photomasks for semiconductor device (LSI) manufacturing, in which the degree of integration is high compared to the display device and the pattern miniaturization has progressed remarkably, in order to obtain high resolution, the exposure device has a high NA (Numerical Aperture) (for example, 0.2 or more) was applied, and the wavelength of exposure light was shortened, and KrF and ArF excimer lasers (single wavelengths of 248 nm and 193 nm, respectively) became widely used.

On the other hand, in the field of lithography for manufacturing a display device, it is not common for the above method to be applied to improve resolution. Rather, the NA of the exposure apparatus known as for 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. , has tended to focus on production efficiency and cost rather than resolution or depth of focus.

However, as mentioned above, also in the manufacture of a display device, the request|requirement of the refinement|miniaturization of a pattern 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, switching to a high-resolution exposure apparatus having a high NA (numerical aperture) requires a large investment, and compatibility with the price of the display apparatus is not obtained. Alternatively, when the exposure wavelength is changed (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. It is not suitable in that it requires a significant investment.

Moreover, as mentioned later, the photomask for display devices has manufacturing restrictions and specific various problems different from the photomask for semiconductor device manufacture.

From the above circumstances, it is practically difficult to divert the photomask of Patent Document 1 as it is for display device manufacture. Moreover, although the halftone type phase shift mask of patent document 2 has description that light intensity distribution improves compared with a binary mask, there exists room for performance improvement further.

Therefore, in the manufacturing method of the display device using the mask for display device manufacturing, it was desired to overcome the said subject and to perform the transcription|transfer on a to-be-transferred object stably as a fine pattern. Accordingly, an object of the present invention is to obtain an excellent photomask that is advantageously suited to the 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.

MEANS TO SOLVE THE PROBLEM In order to solve the said subject, this invention has the following structures. The present invention is a photomask having the following configurations 1 to 14, and a method for manufacturing a display device characterized by 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 W1 (μm) and a width d ( μm), a representative wavelength in a wavelength range of i-line to g-line that passes through the main pattern and a low light-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 the auxiliary pattern is T1 (%), and the light transmittance of the representative wavelength that transmits the low light transmittance portion is T3 ( %), and when the distance between the center of the main pattern and the center of the auxiliary pattern in the width direction is P (µm), the following Equations 1 to 4 are satisfied.

[Equation 1]

[Equation 2]

[Equation 3]

[Equation 4]

(Configuration 2)

Configuration 2 of the present invention is the photomask according to Configuration 1, wherein, in the auxiliary pattern, 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 according to Configuration 2, wherein the transmittance T1 (%) of the semitransmissive film satisfies the following formula (5).

[Equation 5]

(Configuration 4)

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

(Configuration 5)

In Configuration 5 of the present invention, 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 semi-transmissive film on the transparent substrate, and the low light-transmitting portion , Configuration 2, characterized in that on the transparent substrate, the semi-transmissive film and the low-transmissive film having a light transmittance of T2 (%) of the representative wavelength are laminated in this order or in the reverse order, It is the photomask as described in any one of thru|or 4.

(Configuration 6)

In configuration 6 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 formed by forming the semi-transmissive film on the transparent substrate, and the low light-transmitting portion , Configuration 2, characterized in that on the transparent substrate, the semi-transmissive film and the low-transmissive film having a light transmittance of T2 (%) of the representative wavelength are laminated in this order or in the reverse order, It is the photomask as described in any one of thru|or 4.

(Configuration 7)

In 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 oxide of these materials The photomask according to any one of Configurations 2 to 6, characterized in that it is made of a material containing nitrided carbide.

(Configuration 8)

Configuration 8 of the present invention is the photomask according to Configuration 1, wherein the auxiliary pattern exposes the transparent substrate.

(Configuration 9)

In 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 formed by exposing a part of the main surface of the transparent substrate, and the low light-transmitting portion, It is the photomask as described in the description in Configuration 8, wherein a low-transmitting film having a light transmittance of T3 (%) of the representative wavelength is formed on the transparent substrate.

(Configuration 10)

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

(Configuration 11)

Configuration 11 of the present invention is characterized in that a hole pattern having a transfer diameter W2 of 3.0 (μm) or less (provided that W1 > W2) is formed on an object to be transferred corresponding to the main pattern, Configurations 1 to It is the photomask in any one of 10.

(Configuration 12)

According to 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 transfer object is a bias β (μm),

[Equation 6]

It is the photomask of Configuration 11, characterized in that it is.

(Configuration 13)

In configuration 13 of the present invention, the transmittance T3 (%) of the low light-transmitting portion with respect to the light of the representative wavelength is;

[Equation 7]

It is the 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 light-transmitting portion does not substantially transmit light of the representative wavelength.

(Configuration 15)

Configuration 15 of the present invention comprises the steps of preparing the photomask according to any one of Configurations 1 to 14, and exposure comprising at least one of i-line, h-line, and g-line having a numerical aperture (NA) of 0.08 to 0.20. A method of manufacturing a display device, comprising the steps 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 an object to be transferred.

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

BRIEF DESCRIPTION OF THE DRAWINGS It is a top schematic diagram of an example of the photomask of this 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)-(f) of the layer structure of the photomask of this invention.
It is a cross-sectional schematic diagram and plan schematic diagram which show an example of the manufacturing process of the photomask of this invention.
Fig. 5 is a schematic plan view of the photomasks of Comparative Examples 1-1 and 1-2 and Example 1, dimensions, and diagrams showing transfer performance by optical simulation.
6 shows (a) a spatial image of light intensity formed on an object to be transferred, and (b) a cross-sectional shape of a resist pattern formed thereby in the case of using the photomasks of Comparative Examples 1-1 and 1-2 and Example 1; It is a drawing showing
Fig. 7 is a schematic plan view of the photomasks of Comparative Examples 2-1 and 2-2 and Example 2, dimensions, and diagrams showing transfer performance by optical simulation.
Fig. 8 shows (a) a spatial image of light intensity formed on an object to be transferred, and (b) a cross-sectional shape of a resist pattern formed thereby when the photomasks of Comparative Examples 2-1 and 2-2 and Example 2 were used; It is a drawing showing

When the CD (Critical Dimension, hereinafter used as the meaning of the pattern line width) of the transfer pattern of the photomask is miniaturized, the process of accurately transferring it to the transfer object (the thin film to be etched, also called the object) is carried out. it gets more difficult The resolution limit shown as a specification for the exposure apparatus for display apparatuses is about 2-3 micrometers in most cases. On the other hand, among the transfer patterns to be formed, those having a size close to or smaller than this have already appeared. In addition, since the mask for manufacturing a display device has a larger area compared to a mask for manufacturing a semiconductor device, it is very difficult in actual production to uniformly transfer a transfer pattern having a CD of less than 3 µm in-plane.

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

Moreover, since the area of the to-be-transferred body (flat panel display board|substrate) is large, it can be said that it is an environment where defocus resulting from the surface flatness of a to-be-transferred body is easy to generate|occur|produce in the process of pattern transfer by exposure. Under this environment, it is very meaningful to sufficiently secure the degree of focus (DOF) during exposure.

In addition, as is well known, the photomask for display device manufacturing has a large size, and in the wet processing (development or wet etching) in the photomask manufacturing process, the CD (line width) uniformity at various positions in the plane. It is not easy to obtain In order to accommodate the final CD precision within the prescribed tolerance range, it is essential to ensure a sufficient depth of focus (DOF) in the exposure process, and it is also 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. The plan schematic diagram of the pattern for transcription|transfer which the photomask of this invention has is illustrated in FIG.

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) arranged in the vicinity of the main pattern. Further, a low light-transmitting portion is formed in a region other than where the main pattern and the auxiliary pattern are formed.

Here, the transmittance of light having a representative wavelength in the wavelength region of the i-line to g-line passing through the auxiliary pattern is T1, and the transmittance of light having the representative wavelength passing 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 P (µm). At this time, the photomask of this invention satisfy|fills the following relationship.

[Equation 1]

[Equation 2]

[Equation 3]

[Equation 4]

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

In addition, the light transmittances T1 and T3 here are based on the transmittance|permeability of a transparent substrate, and are determined by the layer structure of the applicable part.

A schematic cross-sectional view of such a transfer pattern can be shown in Fig. 3(a), for example. This is set as the 1st form of the photomask of this invention, and is demonstrated with reference to Fig.3 (a).

In this aspect, the main pattern includes the light-transmitting part to which the transparent substrate was exposed. Further, a film having a high transmittance may be formed on the main pattern. However, since the maximum transmittance can be obtained, it is preferable to set it as the structure in which the transparent substrate is exposed without forming a film|membrane with high transmittance|permeability in a main pattern.

In addition, the auxiliary pattern of this embodiment includes a semi-transmissive portion in which a semi-transmissive film is formed on a transparent substrate. This semitransmissive 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 transmittance T1 (%) with respect to the representative wavelength. In addition, 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 the transparent substrate. That is, in the transfer pattern shown in Fig. 1, regions other than the region where the main pattern and the auxiliary pattern are formed are low-transmitting portions. As shown to Fig.3 (a), in this form, the semitransmissive film and the low transmissive film of the low transmissive part are laminated|stacked on the transparent substrate. Further, the low-transmitting portion may be laminated on a transparent substrate with a semi-transmissive film and a low-transmissive film having a light transmittance of T2 (%) of a representative wavelength in this order or in the reverse order.

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

T3<T1

It is good to adjust the transmittance|permeability T3 (%) of the low light-transmitting part by selecting the transmittance|permeability T2 (%) of the low light-transmitting film so that it may become this.

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) (where W1 > W2) on the transfer object corresponding to this main pattern can form.

Specifically, W1 (μm) is represented by the following formula (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

can be done with

In addition, the photomask of the present invention can be used for the purpose of forming a pattern having a fine size useful for manufacturing a display device. For example, when the diameter W1 of a main pattern is 3.0 (micrometer) or less, the effect of this invention is acquired more notably. Preferably, the diameter W1 (μm) of the main pattern,

1.0≤W1≤3.0

can be done with In addition, although the relationship between the diameter W1 and the diameter W2 can also be made into W1=W2, Preferably it is made into W1>W2. That is, when β (μm) is the bias value,

β=W1-W2>0 (μm)

when,

0.2≤β≤1.0

More preferably,

0.2≤β≤0.8

can be done with In doing so, advantageous effects such as reducing the loss of the resist pattern on the transfer object can be obtained as will be described later.

In the above, the diameter W1 of the main pattern means the diameter of a circle or a numerical value approximate 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 same applies to the diameter W2 of the transferred main pattern in that it is the diameter of a circle or a numerical value approximated thereto.

Of course, when forming a finer pattern, W1 can be 2.5 (㎛) or less, or 2.0 (㎛) or less, and furthermore, the present invention can be applied by setting W1 to 1.5 (㎛) or less have.

Further, in the photomask of the present invention, the diameter W1 of the main pattern, the diameter W2 of the main pattern on the transfer object, and the above preferred ranges for the setting of the bias are the photomasks of the present invention according to the second to sixth aspects below. Also in a mask, it can apply similarly.

With respect to the representative wavelength of the exposure light used for exposure of the photomask of the present invention having such a transfer pattern, the phase difference phi between the main pattern and the auxiliary pattern is approximately 180 degrees. That is, the phase difference phi 1 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 approximately 180 degrees, it means 120 to 240 degrees. Preferably, the phase difference ?1 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 exposure light containing i-line, h-line, or g-line is used, exposure light containing 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 the exposure light. In this case, the representative wavelength may be any of i-line, h-line, and g-line. For example, the photomask of the present invention can be configured by using the h-line as a representative wavelength.

In order to form such a phase difference, the main pattern is a light-transmitting portion with the main surface of the transparent substrate exposed, and the auxiliary pattern is a semi-transmissive portion formed by forming a semi-transmissive film on the transparent substrate. What is necessary is just to make the phase shift amount with respect to a wavelength about 180 degree|times.

In addition, about the preferable range of the phase difference between a main pattern and an auxiliary pattern, and the wavelength of exposure light applied to the photomask of this invention, also in the photomask of this invention which concerns on the following 2nd - 6th aspect, it is the same.

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 semi-transmissive film formed on the semi-transmissive portion with respect to the representative wavelength is T1 (%),

30≤T1≤80

do it with More preferably,

40≤T1≤75

am. In addition, let the transmittance|permeability T1 (%) be the transmittance|permeability of the said representative wavelength when the transmittance|permeability of a transparent substrate is used as a reference.

In the photomask of the present invention, the low light-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 light-transmitting portion may substantially not transmit exposure light (light having a representative wavelength in the wavelength range of i-line to g-line). In this case, as a low-transmitting film alone, a low-transmitting film that does not substantially transmit the representative wavelength (that is, a light-shielding film), T2≤0.01, that is, a low-transmissive film having an optical density of OD≥2 may be applied, or a combination of a low-transmissive film and a semi-transmissive film As a laminated film, it is good also as a substantially light-shielding film (optical density OD≥2).

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

T3<T1

will satisfy Preferably,

0.01<T3<30

More preferably,

0.01<T3≤20

meet the Also about the transmittance|permeability T3 (%), let it be the transmittance|permeability of the said representative wavelength when the transmittance|permeability of a transparent substrate is used as a reference.

In this way, when the low-transmission portion transmits exposure light with a predetermined transmittance, the phase difference phi 3 between the transmitted light of the low-transmission portion and the transmitted light of the light-transmitting portion is preferably 90 degrees or less, and more preferably 60 degrees or less. am. “90 degrees or less” means that the phase difference is “(2n-1/2)π to (2n+1/2)π (where n is an integer)” when expressed in radians. Similarly to the above, it is calculated as the phase difference with respect to the representative wavelength included in the exposure light.

Therefore, in this case, as a single property of the low light-transmitting film used for the photomask of this form, it has a transmittance|permeability [T2 (%)] of less than 30 (%) (that is, 0<T2<30), and a phase shift amount ( It is preferable that ?2) is approximately 180 degrees. By approximately 180 degrees, it means 120 to 240 degrees. Preferably, the phase difference ?1 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|stacking, phi 3 can be made into the above-mentioned range.

Similarly to the above, the transmittance here is also the transmittance of the representative wavelength when the transmittance of the transparent substrate is taken as a reference.

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

[Equation 2]

When is established, the excellent effect of the invention is obtained. That is, when √(T1/100) x d is within the above range, the amount of light transmitted through the auxiliary pattern interacts with that of the main pattern in a balanced way to improve the transferability of the main pattern.

At this time, the distance between the center of the main pattern and the center of the auxiliary pattern in the width direction is the 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

can be done with

In the present invention, the auxiliary pattern has the effect of exerting an optical action such as a pseudo 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 passing through exhibits 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 below the resolution limit under the exposure conditions (exposure apparatus used) applied to the photomask of the present invention.

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

Further, more preferably, the relational expression of the above formula (2) is the following formula (2-1), and still more preferably, the following formula (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 rotationally symmetric shape, including an octagon or a circle. And the center of rotational symmetry can be made into the center used as the reference|standard of the said P.

In addition, although the shape of the auxiliary pattern of the photomask shown in FIG. 1 is an octagonal band, this invention is not limited to this. It is preferable that the shape of the auxiliary pattern is a shape of a rotation target that is symmetric or more symmetric with respect to the center of the hole pattern and has a certain width. Preferred shapes of the main pattern and auxiliary pattern are the shapes illustrated in FIGS. You may combine things.

For example, a case in which 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 exemplified. Further, 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 polygon or a circular band having a substantially constant width. This band-like shape is also called a polygonal band or a circular band. As the shape of the auxiliary pattern, it is preferable that such a regular polygonal band or a circular band surround the periphery of the main pattern. At this time, since the balance of the light amount of 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 the interaction of light for obtaining the effect of this 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 an object to be transferred. It is possible to reduce the resist loss of the portion to be used.

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

Moreover, as long as the effect of this invention is not impaired, you may use other patterns in addition to the main pattern of this invention and auxiliary|assistant pattern.

An example of the manufacturing method of the photomask of this form is demonstrated below with reference to FIG.

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 has a transmittance of 30 to 80 (%) on the main surface of the transparent substrate when any one of i-line, h-line, and g-line is the representative wavelength [when 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 the same film as approximately 180 degrees. With such a semi-transmissive film, the phase difference of transmitted light between the main pattern including the light-transmitting 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 the representative wavelength in the wavelength range of the i-line to the g-line by approximately 180 degrees. As a film-forming method of a semitransmissive film, well-known methods, such as a sputtering method, are applicable.

The semi-transmissive film is preferably made of a material that satisfies the transmittance and retardation described above and can be wet-etched as described below. However, if the amount of side etching generated during wet etching is excessively large, problems such as deterioration of CD accuracy and destruction of the upper layer film due to undercutting occur. Therefore, the range of the film thickness is preferably 2000 angstroms or less. For example, it is in the range of 300 to 2000 Angstroms, more preferably 300 to 1800 Angstroms. Here, CD is a Critical Dimension, and in this specification, it is used in the meaning of a pattern line width.

Further, in order to satisfy these conditions, the semitransmissive film material preferably has a refractive index of 1.5 to 2.9 at a representative wavelength (eg, h line) included in the exposure light. More preferably, it is 1.8-2.4.

Moreover, in order to fully exhibit a phase shift effect, it is preferable that the pattern cross section (etched surface) by wet etching is close|similar to perpendicular|vertical with respect to the transparent substrate main surface.

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

On the semi-transmissive film of the photomask blank, a low-transmissive film is formed. As a film-forming method, a well-known means, such as a sputtering method, can be applied similarly to the case of a semitransmissive film.

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

On the other hand, when the low transmissive film can transmit the exposure light, the transmittance and the phase shift amount of the low transmissive film with respect to the exposure light can achieve the transmittance and the phase shift amount of the low light transmitting portion of the photomask of the present invention. that is required Preferably, in the laminated state of the low-transmissive film and the semi-transmissive film, the transmittance T3 (%) with respect to the light of the representative wavelength of the exposure light is 0.01 < T3 < 30, preferably 0.01 < T3 ≤ 20, and , phase shift amount (phi)3 is 90 (degrees) or less, More preferably, it is made into 60 (degrees) or less.

As a single property of the low-transmission film, it does not substantially transmit light of the above representative wavelength, or has a transmittance [T2(%)] of less than 30(%) (ie, 0<T2<30), and a phase It is preferable that the shift amount phi 2 is approximately 180 degrees. By approximately 180 degrees, it means 120 to 240 degrees. Preferably, the phase difference ?1 is 150 to 210 (degrees), more preferably 170 to 190 (degrees).

The material of the low light-transmitting film of the photomask blank may be Cr or a compound thereof (oxide, nitride, carbide, oxynitride, or oxynitride carbide), or a metal silicide containing Mo, W, Ta, Ti, or The compound of the silicide may be used. 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 with respect 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 light-transmitting film of the photomask blank, a first photoresist film is further applied. The photomask of the present invention is preferably drawn with a laser drawing device, so a photoresist suitable therefor is used. A positive type or a negative type may be sufficient as a 1st photoresist film, However, Hereinafter, it demonstrates as a positive type.

Next, as shown in FIG.4(b), with respect to the 1st photoresist film, a writing apparatus is used and writing is performed by writing data based on the pattern for transcription|transfer (1st writing). Then, using the first resist pattern obtained by development as a mask, the low-transmissive film is wet-etched. Thereby, a region to be the low-transmitting portion is defined, and a region of the auxiliary pattern (low-transmitting film pattern) surrounded by the low-transmitting portion is defined. As the etching liquid (wet etchant) for wet etching, a well-known thing suitable for the composition of the low light-transmitting film to be used can be used. For example, if it is a film containing Cr, cerium ammonium nitrate or the like can be used as the wet etchant.

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

Next, as shown in Fig. 4(d), a second photoresist film is applied over the entire surface including the formed low-transmission film pattern.

Next, as shown in FIG.4(e), with respect to the 2nd photoresist film, 2nd writing is performed, and the 2nd resist pattern formed by image development is formed. Using this second resist pattern and the low-transmissive film pattern as masks, the semi-transmissive film is wet-etched. 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 the region serving as the auxiliary pattern, and has an opening in the region serving as the main pattern including the light-transmitting portion, and the second drawing is performed so that the edge of the low-transmission film is exposed from the opening. It is preferable to perform sizing on the data. By doing in this way, it is possible to absorb the misalignment of alignment that occurs between the first drawing and the second drawing, and it is possible to prevent deterioration of the CD accuracy of the transfer pattern. This is the effect of utilizing the etching selectivity with respect to each other film|membrane which the material of a low transmissive film and a semitransmissive film has.

Further, in the photomask of this embodiment, the semi-transmissive film and the low-transmissive film may be made of a material having a common etching characteristic without etching selectivity, and an etching stopper film may be formed between the both films.

That is, by sizing the second resist pattern at the time of second drawing in this way, when an isolated hole pattern is formed on a transfer object, 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 semi-transmissive film is appropriately selected according to the composition of the semi-transmissive 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 the manufacture of a photomask for a display device, when patterning an optical film such as a light-shielding film formed on a transparent substrate, examples of the etching applied include dry etching and wet etching. Either may be employed, but wet etching is particularly advantageous in the present invention. This is because the size of the photomask for display devices is comparatively large, and there exist many types of sizes. When dry etching using a vacuum chamber is applied when manufacturing such a photomask, inefficiencies occur in the size of the dry etching apparatus or in the manufacturing process.

However, there also exists a subject accompanying the application of wet etching at the time of manufacture of such a photomask. Since wet etching has isotropic etching properties, when a predetermined film is etched in the depth direction to elute it, the etching proceeds also in a direction perpendicular to the depth direction. For example, when a slit is formed by etching a semi-transmissive film having a film thickness of F (nm), the opening of the resist pattern serving as an etching mask is 2F (nm) (that is, one side F (nm)) than the desired slit width. Although it is made small, it is difficult to maintain the dimensional accuracy of a resist pattern opening, so that it becomes a slit with a fine width. For this reason, it is useful that the width d of the auxiliary pattern be 1 (μm) or more, preferably 1.3 (μm) or more.

Moreover, when the said film thickness F (nm) is large, since a side etching amount also becomes large, it is advantageous to use the film material which has a phase shift amount of about 180 degrees even if the film thickness is small, As a result, it is half with respect to the said wavelength. 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 for the above representative wavelength to form a semi-transmissive film.

By the way, as for the photomask of this invention shown in FIG. 1, other than the said aspect, there exist some which exhibit the similar optical effect by another layer structure.

A second aspect of the present invention has a layered structure in which a cross section is shown in Fig. 3B. Although the schematic plan view of this photomask is as shown in FIG. 1 similarly to the said 1st form, the laminated structure at the time of a cross-sectional view is different. That is, in the low-transmissive portion shown in FIG. 3B , the stacking order of the low-transmissive film and the semi-transmissive film is reversed, and the low-transmissive 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 the optical action and effect thereof are the same as those of the photomask of the first form, and the modified example shown in FIG. 2 is applicable as the design design. also the same In addition, the physical properties of the membrane material to be used can be made the same.

However, in the photomask of the second aspect, there is a slight difference from the first aspect in the following points on the manufacturing method, and for this reason, also in the film material to be used, it is not necessarily the same as that of the first aspect. .

For example, in the first aspect, as shown in Fig. 4(a), a photomask blank in which a semi-transmissive film and a low-transmissive film are laminated is prepared, and a photolithography process is applied thereto twice, and the photo Although the mask was manufactured, in a 2nd aspect, it is necessary to prepare the photomask blank in which only the low-transmission film was formed into a film on the transparent substrate.

Then, the low transmissive film is first etched to form a low transmissive film pattern. Then, a semi-transmissive film is formed on the entire surface of the substrate on which the low-transmissive film pattern is formed, and this is patterned. In this case, as in the first aspect, it is preferable to select a material that can be patterned by wet etching. However, in this embodiment, it is not essential that the low-transmissive film and the semi-transmissive film have resistance to each other's etchants. That is, etching is possible even if both films have no etching selectivity to each other. Therefore, the degree of freedom is higher than that of the first aspect with respect to the selection of the material.

Next, a 3rd aspect of the photomask of this invention is demonstrated with reference to FIG.3(c). Also in this form, the plan schematic diagram is the same as that of Fig. 1, and the design of the pattern, its respective parameters, and optical effects by 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 modification shown in FIG. 2 is applicable.

The photomask of the third form shown in Fig. 3C is different from the photomasks of the first and second forms in that the amount of phase shift with respect to the light of the representative wavelength that the semi-transmissive film has is approximately 180 degrees. It is a point that is not restricted, and in this regard, in the main pattern portion, the transparent substrate is penetrated by a predetermined amount. That is, in the main pattern of this form, instead of exposing a part of the main surface of the transparent substrate used as the material, a dimpled surface in which a predetermined amount of dimples are formed by etching is exposed on the main surface. And, between the auxiliary pattern in which the semi-transmissive film is formed and the main pattern in which the recess is formed, the phase difference between the representative wavelengths in the wavelength range of the i-line to the g-line that passes through each other is adjusted by approximately 180 degrees. As with the photomasks of the first and second modes, the low-transmitting portion is formed on a transparent substrate by a semi-transmissive film and a low-transmissive film having a light transmittance of T2 (%) of a representative wavelength in this order or in the reverse order It may be a stacked structure.

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

From this point, the phase shift amount with respect to the light of the said representative wavelength which a semitransmissive film has in the photomask of this form may be 90 degrees or less, or 60 degrees or less may be sufficient as it. What is necessary is just to adjust so that the phase difference of the representative wavelength which transmits through a main pattern and an auxiliary pattern may be about 180 degrees by the sum of the amount of dents of a main pattern and the phase shift amount which a semitransmissive film has.

Moreover, in the photomask of a 3rd aspect, although wet or dry etching is used for formation of the recessed part of a transparent substrate, More preferably, dry etching is applied. 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 light-transmitting film are laminated on a transparent substrate is prepared, first, both films of the main pattern portion are etched away, and then the transparent substrate is subjected to a process of etching the recesses. can Next, the photomask of the third form can be manufactured by etching and removing the low light-transmitting film in the auxiliary pattern portion by the second photolithography process. In this case, as a film material, it can carry out similarly to 1st aspect.

In addition, similarly to the relationship between the first aspect and the second aspect, also in the photomask of the third aspect, the stacking order of the semitransmissive film and the low light transmittance film may be reversed vertically.

Next, with reference to FIG.3(d), the 4th aspect of the photomask of this invention is demonstrated. Also in this form, a plan schematic diagram is as showing in FIG. In the fourth aspect, similarly to the third aspect, a recess is formed in the transparent substrate of the main pattern portion, but unlike the third aspect, a semi-transmissive film is not used, and the transparent substrate (part of the main surface) of the auxiliary pattern portion is is exposed Then, by selecting the depth of the dimples in the main pattern portion, similarly to the first to third aspects, the optical phase difference of the representative wavelengths passing through the main pattern and the auxiliary pattern is approximately 180 degrees.

In this fourth aspect, since the semitransmissive 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, whereby advantages such as improvement in production efficiency and reduction in the probability of occurrence of defects are obtained 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.

Moreover, the phase shift amount with respect to the light of the said representative wavelength which the low transmissive film used for the photomask of a 4th form has does not need to be about 180 degrees, and it is preferable that it is 90 degrees or less. More preferably, it is 60 degrees or less.

Also in the photomask of the fourth aspect, the design of the pattern shown in Fig. 1, each parameter other than those described above, and the optical action effect by them are the same as those of the photomask of the first aspect, and as a design design, 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 made the same as that of the first aspect. That is, the low-transmitting portion has a transmittance of T3 (%) at the representative wavelength, but this can have a structure in which a low-transmittance 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.

Incidentally, in the fourth aspect, in the fifth aspect (FIG. 3(e)), the cross-sectional structures of the main pattern and the auxiliary pattern are reversed. 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 depression is formed in the main surface of the transparent substrate. That is, the optical retardation of the representative wavelength transmitted through the main pattern and the auxiliary pattern is approximately 180 degrees by digging into the transparent substrate of the auxiliary pattern portion in response to a change in the formation of the transparent substrate recess of the main pattern portion. Even in this case, it goes without saying that the planar design and its optical effects are the same as those of the fourth aspect. Moreover, there is no difference in particular also about the manufacturing method, the film material to be applied, etc. Accordingly, in the low transmissive portion of the fifth aspect, a low transmissive film having a light transmittance of a representative wavelength of T2 (%) is formed on a transparent substrate.

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

That is, in the vicinity of the main pattern and the auxiliary pattern, the interference action of out-of-phase light is used, but in the region of the low light-transmitting portion separated from the above, the existence of light passing through the low-transmitting film is unnecessary, rather, it is formed on the transfer object. There is a risk of causing a disadvantage of reducing the remaining film amount of the resist pattern. When this risk is to be eliminated, it is also useful to completely block light by adding a light-shielding film pattern in a region of the low light-transmitting portion spaced apart from the main pattern and the auxiliary pattern.

Therefore, in the present invention, use of such a light-shielding film pattern is not prevented as long as the effect is not impaired. In addition, the light-shielding film|membrane means the film|membrane of OD (optical density) 2 or more which does not substantially transmit exposure light (light of the representative wavelength of the said i-line to g-line range). Examples of the material include those containing chromium (Cr) as a main component.

The present invention includes a method for manufacturing a display device, comprising the steps of exposing the photomask of the present invention to light with an exposure apparatus, transferring the transfer pattern onto a transfer target, and forming a hole pattern. do.

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

As an exposure machine used when transferring a transfer pattern using the photomask of this invention, it is a system which performs projection exposure of equal magnification, The following are mentioned. That is, it is an exposure machine used as an LCD (liquid crystal display device) (or FPD, liquid crystal), and its configuration has a numerical aperture (NA) of an optical system of 0.08 to 0.15 [a coherence factor (σ) of 0.4 to 0.9] and has 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 the exposure light. However, it is of course possible to obtain the effect of the invention by applying the present invention also in an exposure apparatus having a numerical aperture NA of 0.10 to 0.20.

In addition, although deformed illumination (annular illumination etc.) may be used for the light source of the exposure apparatus to be used, even if it is non-deformation illumination, the outstanding effect of invention is acquired.

The present invention provides a photomask blank in which a semi-transmissive film and a low-transmitting film (and, if necessary, a light-shielding film) are laminated on a transparent substrate as a raw material for the photomask of the first to third forms (and the sixth form to which it is applied). use Then, a resist film is further formed by coating 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 photomask blank preferably has a transmittance T1 of 30 to 80 (%) with respect to a representative wavelength in the wavelength range of the i-line to the g-line. In addition, the said semitransmissive film has a refractive index of 1.5-2.9 with respect to the said representative wavelength, and has become the film thickness which has a phase shift amount of about 180 degrees. Even if the film thickness of the semitransmissive film which has such a refractive index is thin enough, since it has a desired phase shift amount, the wet etching time of a semitransmissive film can be shortened. As a result, side etching of the semi-transmissive film can be suppressed.

Moreover, in all the forms of the photomask of this invention, it can manufacture using the photomask blank in which the low light-transmitting film was formed into a film.

As the low-transmission film, substantially no light having the representative wavelength is transmitted, or a film having a transmittance of less than 30% can be used. In addition, the phase shift amount with respect to the representative wavelength within the range of the i line|wire - g line which the low light-transmitting film has is approximately 180 degrees in the photomask according to the first and second aspects, and the photomask according to the third, fourth and fifth aspects In a mask, it is 90 degrees or less, What is necessary is just to set it as 60 degrees or less more preferably.

[Example]

The optical simulation compared and evaluated the transfer performance of 3 types (Comparative Examples 1-1 and 1-2, and Example 1) of the photomasks shown in FIG. 5 by optical simulation. In other words, optical simulation was performed for three photomasks having a transfer pattern for forming a hole pattern having a diameter of 2.0 μm on an object to be transferred, and what kind of transfer performance would be exhibited when the exposure conditions were 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 (one side of a square) of the main pattern is 2.0 (micrometer).

(Comparative Example 1-2)

As shown in FIG. 5 , the photomask of Comparative Example 1-2 has one side (diameter) (ie, W1) formed by patterning a semitransmissive film having an exposure light transmittance (pair h line) of 5% and a phase shift amount of 180 degrees. ) is a halftone phase shift mask having a main pattern including a rectangular light-transmitting portion of 2.0 (μm).

(Example 1)

5, the photomask of Example 1 has the pattern for transcription|transfer of this invention. Here, the main pattern is a square with one side (diameter) (ie, W1) of 2.0 (㎛), the auxiliary pattern is an octagonal band with a width d of 1.3 (㎛), the center of the main pattern and the center of the width of the auxiliary pattern The pitch P which is the distance of was set to 4 (micrometer).

The auxiliary pattern assumes the photomask of the first aspect in which a semi-transmissive film is formed on a transparent substrate. The exposure light (large h line) transmittance T1 of this semitransmissive 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 is formed of a light-shielding film (OD>2) that does not substantially transmit the exposure light.

For any of the photomasks of Comparative Examples 1-1 and 1-2 and Example 1, the diameter W2 on the transfer object was 2.0 µm (W1 = W2. That is, the diameter W2 formed on the transfer object was It is assumed that a hole pattern having the same diameter W1 of the main pattern included in the transfer pattern of the mask is formed. The exposure conditions applied by simulation are as follows. That is, the exposure light had 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 a NA of 0.1 and a coherence factor σ of 0.5. The film thickness of the positive photoresist for obtaining the cross-sectional shape of the resist pattern formed on the to-be-transferred body was 1.5 micrometers.

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

(Optical evaluation of photomask)

For example, in order to transfer a fine transmissive pattern with a small diameter, the profile of the transmitted light intensity curve must be favorable in the spatial image that the exposure light after transmission through the photomask forms on the to-be-transferred object. Specifically, those that form a peak of transmitted light intensity have a sharp inclination and have a near-vertical rising direction, and those that have a high absolute value of the light intensity of the peak (if a sub-peak is formed around it, the intensity is relatively high enough), etc., are critical.

More quantitatively, when evaluating a photomask from optical performance, the following index|index can be used.

(1) Depth of Focus (DOF)

For the target CD, the magnitude of the depth of focus to be within the range of ±10%. When the numerical value of DOF is high, it is hard to be influenced by the flatness of the to-be-transferred object (for example, the panel board|substrate for display apparatuses), a fine pattern can be formed reliably, and the CD (line|wire width) deviation is suppressed.

(2) MEEF (Mask Error Enhancement Factor)

It is a numerical value indicating the ratio of the mask CD error to the CD error of the pattern formed on the transfer object. The lower the MEEF, the lower the CD error of the pattern formed on the transfer object.

(3) Eop

In the photomask for display device manufacture, there exists Eop in a particularly important evaluation item. This is the amount of exposure light required to form the desired pattern size on the transfer object. In display device manufacturing, since the size of the photomask is large (for example, a square or rectangle with one side of the main surface of about 300 to 1400 mm), it is possible to increase the speed of scanning exposure by using a photomask with a low Eop value. Thus, the 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. It is a very good point by comparison, and shows stable transferability of the pattern. This means that the value of MEEF is small and the CD precision of a fine pattern is high.

In addition, the value of the photomask Eop of Example 1 is very small. This shows that, in the case of the photomask of Example 1, the exposure time does not increase or can be shortened even in the manufacture of a large-area display device.

Further, referring to the spatial image of 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 is the threshold value at which the resist is photosensitive. and it can be seen that the slope of the peak can be sufficiently raised (close to perpendicular to the surface of the transfer object). This point is superior compared with Comparative Examples 1-1 and 1-2. Here, an increase in Eop and a reduction in MEEF are achieved by using the light passing through the auxiliary pattern to enhance the light intensity at the position of the main pattern. Further, in the photomask of Example 1, side peaks are generated on both sides of the transfer image position of the main pattern, but since it is equal to or less than Eth, the transfer of the main pattern is not affected.

In addition, the method of reducing the loss of the resist residual film originating in this side peak is demonstrated below.

The design of the transfer pattern formed in the photomask was changed, and simulation was performed using the sample of Comparative Example 2-1, Comparative Example 2-2, and Example 2 shown in FIG. Here, each sample 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 so-called binary mask pattern 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 (micrometer).

(Comparative Example 2-2)

7 , the photomask of Comparative Example 2-1 had a main pattern diameter W1 (square-shaped It is a halftone type phase shift mask which has a main pattern which includes the rectangular light-transmitting part of which one side) is 2.5 (micrometer).

(Example 2)

As shown in FIG. 7, the photomask of Example 2 is the transfer pattern of this invention. The main pattern of the photomask of Example 2 is a square with a diameter W1 (one side of a square) of the main pattern of 2.5 (μm), and the auxiliary pattern is an octagonal band with a width d of 1.3 (μm), the main pattern center and , the pitch P, which is the distance between the width centers of the auxiliary patterns, was set to 4 (μm). Here too, the photomask of Example 2 assumes the photomask of 1st form.

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 is formed on the transfer target body. That is, the mask bias (β=W1-W2) of these photomasks was set to 0.5 (µm). The exposure conditions applied by the simulation were the same as in the case of the photomasks of Comparative Examples 1-1 and 1-2 and Example 1 described above.

As is clear from the data shown in Fig. 7, when the photomask of Example 2 was used, advantageous performances were exhibited for Comparative Examples 2-1 and 2-2, together with excellent DOF and MEEF. In the photomask of Example 2, especially DOF is a numerical value exceeding 35 micrometers.

Further, by referring to the spatial image of transmitted light intensity and the cross-sectional shape of the resist pattern on the transfer object shown in Fig. 8, 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 peak formed on both sides, and almost no resist damage 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 the transfer pattern in the range of 0.2 to 1.0 (μm), it is more practical It has become clear that an excellent transfer image that is easy to perform can be obtained.

As mentioned above, the outstanding performance of the photomask of this invention was confirmed. In particular, when the photomask of the present invention is used, in a fine pattern of 2 μm or less, the MEEF can obtain a numerical value of 2.5 or less, which is significant in manufacturing display devices in the future.

There is no restriction|limiting in particular in the use of the photomask of this invention. The photomask of this invention can be used suitably at the time of manufacture of the display apparatus containing a liquid crystal display device, an EL display device, etc.

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, reduce the zero light blocking during exposure, and relatively increase the ratio of ±1st light. For this reason, the spatial image of transmitted light can be improved significantly.

As an application in which such operational effects can be advantageously obtained, it is advantageous to use the photomask of the present invention for formation of isolated hole patterns, such as contact holes commonly used in liquid crystals and EL devices. As the type of pattern, a dense pattern in which a plurality of patterns are arranged with a certain regularity and thereby optically affect each other, and an isolated pattern in which the pattern of such a regular arrangement does not exist in the vicinity are distinguished and called. Often times. The photomask of the present invention is preferably applied when an isolated pattern is to be formed on an object to be transferred.

As long as the effect of the present invention is 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 a problem that the light transmittance of the low-transmitting film interferes with inspection or position detection of the photomask, the light-shielding film may be formed in a region other than the transfer pattern. Moreover, in a semitransmissive film, you may provide the antireflection layer for reducing reflection of drawing light and exposure light on the surface.

Claims (14)

On the main surface of the transparent substrate, a translucent film having a transmittance T1 of 30 to 80 (%) for a representative wavelength in the wavelength range of i-line to g-line, and a low transmittance for the representative wavelength smaller than the semi-transmissive film A photomask blank for manufacturing a display device in which a light-transmitting film is laminated, comprising:
The semi-transmissive film is a film capable of wet etching, 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 150 to 210 degrees;
The low light-transmitting film can be wet-etched, 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. On the main surface of the transparent substrate, a translucent film having a transmittance T1 of 30 to 80 (%) for a representative wavelength in the wavelength range of i-line to g-line, and a low transmittance for the representative wavelength smaller than the semi-transmissive film A photomask blank for manufacturing a display device in which a light-transmitting film is laminated, comprising:
The semi-transmissive film is a film capable of wet etching, 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 150 to 210 degrees;
The low-transmitting film can be wet-etched, and in a laminated state of the low-transmitting film and the semi-transmissive film, the transmittance T3 (%) for light of the representative wavelength is T3≤20, and the amount of phase shift

3 is less than or equal to 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. 3. The method of claim 1 or 2,
The low light-transmitting film is Cr or Cr oxide, nitride, carbide, oxynitride, or oxynitride carbide, a photomask blank for manufacturing a display device, characterized in that. 3. The method of claim 1 or 2,
The semi-transmissive film 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. , a photomask blank for manufacturing display devices. 3. The method of claim 1 or 2,
A photomask blank for manufacturing a display device, characterized in that the low-transmissive film and the semi-transmissive film are made of a material having a common etching characteristic. delete 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, comprising:
The transcription pattern is
a main pattern having a diameter of W1 (μm) comprising a light-transmitting portion to which the transparent substrate is exposed;
an auxiliary pattern having a width of d (μm), which is disposed in the vicinity of the main pattern and is made of a semi-transmissive portion in which the semi-transmissive film is formed on the transparent substrate;
a low-transmitting portion disposed in a region other than where the main pattern and the auxiliary pattern are formed among the transfer patterns and having at least the low-transmitting film formed on the transparent substrate;
The light-transmitting part is made by exposing the transparent substrate,
The semi-transmissive part is made by forming the semi-transmissive film on the transparent substrate,
The low-transmitting part is made by laminating the semi-transmissive film and the low-transmitting film on the transparent substrate,
Characterized in that the following formulas (1) and (2) are satisfied,

···(One)

···(2)
Photomasks for manufacturing display devices. 8. The method of claim 7,
A photomask for manufacturing a display device, wherein the width d of the auxiliary pattern satisfies d≤W1. 8. The method of claim 7,
In the transfer pattern, the diameter W1 of the main pattern is 4.0 (μm) or less, and a hole pattern having a diameter W2 (however, W1 > W2) is formed on the transfer object corresponding to the main pattern. which, a photomask for manufacturing a display device. 10. The method of claim 9,
The said diameter W2 is 3.0 (micrometer) or less, the photomask for display apparatus manufacture. 10. 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 0.2 ? A method of manufacturing a photomask for manufacturing a display device, comprising:
A step of preparing a photomask blank for manufacturing a display device according to claim 1 or 2;
a step of 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 is
a main pattern having a diameter of W1 (μm) comprising a light-transmitting portion to which the transparent substrate is exposed;
an auxiliary pattern having a width of d (μm), which is disposed in the vicinity of the main pattern and is made of a semi-transmissive portion in which the semi-transmissive film is formed on the transparent substrate;
a low-transmitting portion disposed in a region other than where the main pattern and the auxiliary pattern are formed among the transfer patterns and having at least the low-transmitting film formed on the transparent substrate;
The light-transmitting part is made by exposing the transparent substrate,
The semi-transmissive part is made by forming the semi-transmissive film on the transparent substrate,
The low-transmitting part is made by laminating the semi-transmissive film and the low-transmitting film on the transparent substrate,
Characterized in that the following formulas (1) and (2) are satisfied,

···(One)

···(2)
A method of manufacturing a photomask for manufacturing a display device. A method of manufacturing a display device, comprising: preparing the photomask according to claim 7; and exposing the transfer pattern to light using an exposure apparatus to form a hole pattern on an object to be transferred. A display device comprising the steps of: preparing a photomask for manufacturing a display device according to the manufacturing method according to claim 12; and exposing the transfer pattern using an exposure device to form a hole pattern on a transfer target body manufacturing method.

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