JP6872061B2 - Manufacturing method of photomask and display device - Google Patents

Description

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

In Patent Document 1, as a photomask used for manufacturing a semiconductor device, four auxiliary light-transmitting portions are arranged in parallel with each side of the main light-transmitting portion (hole pattern), and the main light-transmitting portion and the auxiliary light-transmitting portion are arranged. A phase shift mask is described in which the phase of the light of the part is inverted.

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

Japanese Unexamined Patent Publication No. 3-15845 Japanese Unexamined Patent Publication No. 2013-148892

At present, display devices including liquid crystal display devices and EL display devices are desired to be brighter and save power, and to improve display performance such as high definition, high speed display, and wide viewing angle.

For example, in the case of a thin film transistor (“TFT”) used in the display device, among a plurality of patterns constituting the TFT, the contact holes formed in the interlayer insulating film are surely the patterns of the upper layer and the lower layer. Correct operation cannot be guaranteed unless it has the effect of connecting. On the other hand, in order to make the opening ratio of the display device as large as possible to make the display device bright and power-saving, the diameter of the contact hole is required to be sufficiently small. Along with this, it is desired that the diameter of the hole pattern provided in the photomask for forming such a contact hole is also miniaturized (for example, less than 3 μm). For example, a hole pattern having a diameter of 2.5 μm or less and a diameter of 2.0 μm or less is required, and it is considered that it is desired to form a pattern having a diameter of 1.5 μm or less, which is smaller than this, in the near future. Against this background, there is a need for manufacturing technology for display devices that can reliably transfer minute contact holes.

By the way, in the field of photomasks for manufacturing semiconductor devices (LSIs), which have a higher degree of integration than display devices and the pattern miniaturization has been remarkably advanced, in order to obtain high resolution, the exposure device has a high NA. There is a history of shortening the wavelength of the exposure light by applying an optical system (for example, 0.2 or more), and KrF and ArF excimer lasers (single wavelengths of 248 nm and 193 nm, respectively) are often used. Became.

On the other hand, in the field of lithography for manufacturing display devices, it has not been common to apply the above method in order to improve the resolution. Rather, the NA of an exposure apparatus known for LCDs (liquid crystal displays) is about 0.08 to 0.10, and the exposure light source also includes i-line, h-line, and g-line, and has a broad wavelength. By using the region, there is a tendency to emphasize production efficiency and cost rather than resolution and depth of focus.

However, as described above, even in the manufacture of display devices, the demand for miniaturization of patterns is higher than ever. Here, there are some problems in applying the technology for manufacturing a semiconductor device as it is to the manufacturing of a display device. For example, the conversion to a high-resolution exposure device having a high numerical aperture (NA) requires a large investment and is inconsistent with the price of the display device. Alternatively, changing the exposure wavelength (using a short wavelength such as an ArF excimer laser with a single wavelength) is difficult to apply to a display device having a large area, and if it is applied, the production efficiency will be improved. In addition to the decline, it is also inconvenient in that it requires a considerable investment.

Further, as will be described later, the photomask for the display device has various manufacturing restrictions and unique problems that are different from the photomask for manufacturing the semiconductor device.

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

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-mentioned problems and to stably transfer a fine pattern onto a transfer target. Therefore, an object of the present invention is to obtain an excellent photomask and a method for producing the same, which are advantageously adapted to the exposure environment of the mask for manufacturing a display device and can stably transfer a fine pattern.

The present invention has the following configurations in order to solve the above problems. The present invention is a method for manufacturing a photomask having the following configurations 1 to 14 and a display device having the following configurations 15.

１．０ ＜ Ｐ ≦ ５．０ ・・・・・・・・・・・・・・・（３）
Ｔ３ ＜ Ｔ１ ・・・・・・・・・・・・・・・・・・・・・（４） (Structure 1)
The configuration 1 of the present invention is a photomask including a transfer pattern formed on a transparent substrate, and the transfer pattern is arranged in the vicinity of a main pattern having a diameter of W1 (μm) and the main pattern. , An auxiliary pattern having a width d (μm), and a low transmissive portion arranged in a region other than the main pattern and the area where the auxiliary pattern is formed, and i-line to g-line transmitting through the main pattern. The phase difference between the representative wavelength in the wavelength range of 1 and the representative wavelength transmitted through the auxiliary pattern is approximately 180 degrees, and the transmittance of light of the representative wavelength transmitted through the auxiliary pattern is T1 (%). When the transmittance of light of the representative wavelength transmitted through the low transmissive portion is T3 (%) and the distance between the center of the main pattern and the center of the auxiliary pattern in the width direction is P (μm). , A photomask characterized by satisfying the following equations (1) to (4).
0.8 ≤ W1 ≤ 4.0 ... (1)

1.0 <P ≤ 5.0 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ (3)
T3 <T1 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ (4)

(Structure 2)
The configuration 2 of the present invention is characterized in that the auxiliary pattern is formed on the transparent substrate by forming a semipermeable membrane having a transmittance of T1 (%) with respect to light of the representative wavelength. The photomask described.

(Structure 3)
Configuration 3 of the present invention is the photomask according to configuration 2, wherein the transmittance T1 (%) of the semipermeable membrane satisfies the following formula (5).
30 ≤ T1 ≤ 80 ... (5)

(Structure 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.

(Structure 5)
In the configuration 5 of the present invention, the main pattern is formed by exposing a part of the main surface of the transparent substrate, and the auxiliary pattern is formed by forming the semitransparent film on the transparent substrate. In the low translucency portion, the semitransparent film and the low translucent film having a light transmittance of the representative wavelength of T2 (%) are arranged on the transparent substrate in this order or vice versa. The photomask according to any one of configurations 2 to 4, wherein the photomasks are laminated in this order.

(Structure 6)
In the configuration 6 of the present invention, the main pattern is formed by digging on the main surface of the transparent substrate, and the auxiliary pattern is formed by forming the semitransparent film on the transparent substrate. In the low translucency portion, the semitransparent film and the low translucent film having a light transmittance of the representative wavelength of T2 (%) are arranged on the transparent substrate in this order or vice versa. The photomask according to any one of configurations 2 to 4, wherein the photomasks are laminated in this order.

(Structure 7)
In the configuration 7 of the present invention, the translucent film is a material containing at least one of Zr, Nb, Hf, Ta, Mo and Ti and Si, or an oxide, a nitride or an oxide nitride of these materials. The photomask according to any one of configurations 2 to 6, characterized in that it is made of a substance, a carbide, or a material containing an oxide nitride carbide.

(Structure 8)
The configuration 8 of the present invention is the photomask according to the configuration 1, wherein the auxiliary pattern is such that the transparent substrate is exposed.

(Structure 9)
In the configuration 9 of the present invention, the main pattern has a digging formed on the main surface of the transparent substrate, and the auxiliary pattern has a part of the main surface of the transparent substrate exposed, so that the low transparency is achieved. The photomask according to the configuration 8 is characterized in that a low translucent film having a light transmittance of the representative wavelength of T3 (%) is formed on the transparent substrate. Is.

(Structure 10)
In the configuration 10 of the present invention, the main pattern is formed by exposing a part of the main surface of the transparent substrate, and the auxiliary pattern is formed by digging in the main surface of the transparent substrate. The photomask according to the configuration 8 is characterized in that a low translucent film having a light transmittance of the representative wavelength of T3 (%) is formed on the transparent substrate. Is.

(Structure 11)
The configuration 11 of the present invention is characterized in that a hole pattern having a transfer diameter W2 of 3.0 (μm) or less (however, W1> W2) is formed on the transferred body in accordance with the main pattern. The photomask according to any one of configurations 1 to 10.

(Structure 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 transferred object is set as the bias β (μm),
0.2 ≤ β ≤ 1.0 ... (6)
The photomask according to the configuration 11, wherein the photomask is characterized by the above.

(Structure 13)
In the configuration 13 of the present invention, the transmittance T3 (%) of the low translucency portion with respect to the light of the representative wavelength is determined.
T3 <30 ... (7)
The photomask according to any one of configurations 1 to 12, which is characterized by satisfying the above conditions.

(Structure 14)
The configuration 14 of the present invention is the photomask according to any one of configurations 1 to 12, characterized in that the low translucency portion does not substantially transmit light of the representative wavelength.

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

According to the present invention, it is possible to provide an excellent photomask that is advantageously adapted to the exposure environment of a mask for manufacturing a display device and that can stably transfer fine patterns, and a method for manufacturing the same.

It is a plane schematic diagram of an example of the photomask of this invention. Schematic views (a) to (f) of another example of the photomask of the present invention. Examples (a) to (f) of the layer structure of the photomask of the present invention. It is sectional drawing and plane schematic diagram which show an example of the manufacturing process of the photomask of this invention. FIG. 5 is a schematic plan view, dimensions, and a diagram showing transfer performance by optical simulation of the photomasks of Comparative Examples 1-1 and 1-2 and Example 1. (A) A spatial image of the light intensity formed on the transferred object when the photomasks of Comparative Examples 1-1 and 1-2 and Example 1 are used, and (b) a resist pattern formed thereby. It is a figure which shows the cross-sectional shape. It is a plan view of the photomask of Comparative Examples 2-1 and 2-2 and Example 2, and the figure which shows the transfer performance by an optical simulation. (A) A spatial image of the light intensity formed on the transferred object when the photomasks of Comparative Examples 2-1 and 2-2 and Example 2 are used, and (b) a resist pattern formed thereby. It is a figure which shows the cross-sectional shape.

When the CD of the transfer pattern of the photomask (Critical Dimension, hereinafter used to mean the pattern line width) is miniaturized, it is accurately referred to as the transferred object (also referred to as the processed object such as a thin film to be etched). It becomes more difficult to carry out the process of transferring to. The resolution limit specified as a specification for an exposure apparatus for a display device is often about 2 to 3 μm. On the other hand, among the transfer patterns to be formed, those having a size approaching or smaller than this have already appeared. Further, since the mask for manufacturing a display device has a larger area than the mask for manufacturing a semiconductor device, it is very difficult to uniformly transfer a transfer pattern having a CD of less than 3 μm in the plane in actual production.

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

Further, since the area of the transferred body (flat panel display substrate) is large, it can be said that defocusing due to the surface flatness of the transferred body is likely to occur in the pattern transfer process by exposure. In this environment, it is extremely meaningful to secure a sufficient depth of field (DOF) during exposure.

As is well known, photomasks for manufacturing display devices have a large size, and in the wet treatment (development and wet etching) in the photomask manufacturing process, the uniformity of CD (line width) is maintained at every position in the plane. It is not easy to secure. In order to keep the final CD accuracy within the specified allowable range, it is important to secure a sufficient depth of focus (DOF) in the exposure process, and it is desirable that other performance does not deteriorate accordingly. ..

The present invention is a photomask having a transfer pattern formed by patterning a semipermeable membrane and a low permeable membrane formed on a transparent substrate, respectively. A schematic plan view of a transfer pattern included in the photomask of the present invention is illustrated in FIG.

As shown in FIG. 1, the transfer pattern formed on the transparent substrate includes a main pattern having a diameter of W1 (μm) and an auxiliary pattern having a width d (μm) arranged in the vicinity of the main pattern. Further, a low light transmissive portion is formed in a region other than the main pattern and the auxiliary pattern.

１．０ ＜ Ｐ ≦ ５．０ ・・・・・・・・・・・・・・・（３）
Ｔ３ ＜ Ｔ１ ・・・・・・・・・・・・・・・・・・・・・（４） Here, the transmittance for light of a representative wavelength in the wavelength range of i-line to g-line that transmits the auxiliary pattern is T1, and the transmittance for light of the representative wavelength that is transmitted through the low translucency 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 the present invention satisfies the following relationship.
0.8 ≤ W1 ≤ 4.0 ... (1)

1.0 <P ≤ 5.0 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ (3)
T3 <T1 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ (4)

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

The light transmittances T1 and T3 referred to here 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 shown in FIG. 3A, for example. This will be described as the first aspect of the photomask of the present invention with reference to FIG. 3 (a).

In this aspect, the main pattern consists of a translucent portion with an exposed transparent substrate. A film having a high transmittance may be formed in the main pattern. However, in terms of obtaining the maximum transmittance, it is preferable that the main pattern does not form a film having a high transmittance and the transparent substrate is exposed.

Further, the auxiliary pattern of this embodiment comprises a semipermeable membrane in which a semipermeable membrane is formed on a transparent substrate. This semipermeable membrane 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 (%) with respect to the representative wavelength. Further, the portion surrounding the main pattern and the auxiliary pattern is a low translucency portion in which at least a low translucency film is formed on the transparent substrate. That is, in the transfer pattern shown in FIG. 1, the region other than the region where the main pattern and the auxiliary pattern are formed is the low translucency portion. As shown in FIG. 3A, in the present embodiment, the semipermeable membrane and the low permeable membrane are laminated on the transparent substrate in the low translucent portion. In the low transmissive portion, a semi-transmissive film and a low transmissive film having a light transmittance of a representative wavelength of T2 (%) are arranged on a transparent substrate in this order or vice versa. Can be laminated with.

The low translucency portion of the photomask of the present invention has a predetermined low transmittance with respect to the representative wavelength of the exposure light. That is, with respect to light having a representative wavelength in the wavelength range of i-line to g-line, the low-transmittance portion has a transmittance T3 (%) lower than the transmittance T1 (%) of the auxiliary pattern composed of the semi-transmissive portion. Have. Therefore, in the present embodiment (FIG. 3 (a)) in which the low light-transmitting portion is formed by laminating the semipermeable membrane and the low light-transmitting portion, the lamination is used.
T3 <T1
The transmittance T3 (%) of the low light-transmitting portion may be adjusted by selecting the transmittance T2 (%) of the low light-transmitting film so as to be.

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

Specifically, W1 (μm) is expressed by the following formula (1).
0.8 ≤ W1 ≤ 4.0 ... (1)
It is preferable that the relationship is as follows. At this time, the diameter W2 (μm) of the main pattern (hole pattern) formed on the transferred body is 3.0 (μm) or less, specifically,
0.6 ≤ W2 ≤ 3.0
Can be.

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 can be obtained more remarkably. Preferably, the diameter W1 (μm) of the main pattern is set.
1.0 ≤ W1 ≤ 3.0
Can be. The relationship between the diameter W1 and the diameter W2 can be set to W1 = W2, but preferably W1> W2. That is, when β (μm) is used as the bias value,
β = W1-W2> 0 (μm)
When
0.2 ≤ β ≤ 1.0,
More preferably
0.2 ≤ β ≤ 0.8
Can be. When doing so, as will be described later, advantageous effects such as reducing the loss of the resist pattern on the transferred body can be obtained.

In the above, the diameter W1 of the main pattern means the diameter of a circle or a numerical value close 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 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 the diameter of the circle or a numerical value close thereto is used.

Of course, when trying to form a finer pattern, W1 can be 2.5 (μm) or less, or 2.0 (μm) or less, and W1 can be 1.5 (μm) or less. ) The present invention can also be applied as follows.

The above-mentioned preferable ranges regarding the setting of the diameter W1 of the main pattern in the photomask of the present invention, the diameter W2 of the main pattern on the transferred object, and the bias are related to the following second to sixth aspects of the present invention. The same can be applied to a photomask.

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 for exposure of the photomask of the present invention having such a transfer pattern. That is, the phase difference φ1 between the light having the representative wavelength transmitted through the main pattern and the representative wavelength transmitted through the auxiliary pattern is approximately 180 degrees. Approximately 180 degrees means 120 to 240 degrees. Preferably, the phase difference φ1 is 150 to 210 degrees.

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

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

Regarding the preferable range of the phase difference between the main pattern and the auxiliary pattern and the wavelength of the exposure light applied to the photomask of the present invention, the photomask of the present invention according to the second to sixth aspects below also has the same. , The same is true.

In the photomask of the first aspect, that is, the photomask shown in FIG. 3A, the light transmittance T1 of the semipermeable membrane can be as follows. That is, when the transmittance of the semipermeable membrane formed in the semipermeable membrane with respect to the above representative wavelength is T1 (%).
30 ≤ T1 ≤ 80
And. More preferably
40 ≤ T1 ≤ 75
Is. The transmittance T1 (%) is the transmittance of the representative wavelength based on the transmittance of the transparent substrate.

In the photomask of the present invention, the low light-transmitting portion arranged in the region other than the main pattern and the auxiliary pattern formed and formed around the main pattern and the auxiliary pattern can have the following configuration. ..

The low translucency portion may be one that does not substantially transmit exposure light (light having a representative wavelength in the wavelength range of i-line to g-line). In this case, even if a low light-transmitting film that does not substantially transmit the above representative wavelength (that is, a light-shielding film) and has T3 ≦ 0.01, that is, an optical density OD ≧ 2, is applied. Well, or a laminated film of a low-transmissivity film and a semi-transmissive film may be used as a substantially light-shielding film.

Alternatively, the low translucency portion may transmit the exposure light within a predetermined range. However, when the exposure light is transmitted within a predetermined range and the transmittance of the low transmissive portion is T3 (%) (here, in the case of laminating a semipermeable membrane and a low transmissive film, the laminate is used. Transmittance),
T3 <T1
It satisfies. Preferably,
0 ≤ T3 <30
More preferably
0 <T3 ≤ 20
Meet. The transmittance T3 (%) is also the transmittance of the above representative wavelength based on the transmittance of the transparent substrate.

Further, when the low transmissive portion transmits the exposure light with a predetermined transmittance, the phase difference φ3 between the transmitted light of the low transmissive portion and the transmitted light of the transmissive portion is 90 degrees or less. It is preferably 60 degrees or less, more preferably 60 degrees or less. "90 degrees or less" means that the phase difference is "(2n-1 / 2) π to (2n + 1/2) π (where n is an integer)" in radian notation. Similar 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, the low light-transmitting film used in the photomask of this embodiment has a transmittance (T2 (%)) of less than 30 (%) (that is, 0 <T2 <30). The phase shift amount (φ2) is preferably about 180 degrees. Approximately 180 degrees means 120 to 240 degrees. Preferably, the phase difference φ1 is 150 to 210 degrees. As a result, φ3 can be set in the above range for the phase shift characteristic of the low light transmissive portion made of laminated light.

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

が成り立つときに、発明の優れた効果が得られる。このとき、主パターンの中心と、補助パターンの幅方向の中心の距離をピッチＰ（μｍ）とし、ピッチＰは、
１．０ ＜ Ｐ ≦ ５．０
の関係が成り立つことが好ましい。 In the above transfer pattern, when the width of the auxiliary pattern is d (μm),

When is satisfied, the excellent effect of the invention is obtained. At this time, the distance between the center of the main pattern and the center in the width direction of the auxiliary pattern is set to pitch P (μm), and the pitch P is
1.0 <P ≤ 5.0
It is preferable that the relationship of

More preferably, the pitch P is
1.5 <P ≤ 4.5
Can be.

In the present invention, the auxiliary pattern has the effect of exerting an optical action such as a pseudo-Dense Pattern on the main pattern isolated by design, but when the above relational expression is satisfied, the main pattern is main. The exposure light transmitted through the pattern and the auxiliary pattern interacts well with each other, and can exhibit excellent transferability as shown in Examples described later.

The width d (μm) of the auxiliary pattern is a dimension equal to or less than 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.

Further, d ≦ W1 is preferable, and d <W1 is more preferable.

Further, more preferably, the relational expression of the above (2) is the following formula (2) -1, and even more preferably, the following formula (2) -2.

As described above, the main pattern of the photomask shown in FIG. 1 is a square, but the present invention is not limited to this. For example, as illustrated in FIG. 2, the main pattern of the photomask can be a rotationally symmetric shape, including an octagon and a circle. Then, the center of rotational symmetry can be used as the reference center of P.

Further, the shape of the auxiliary pattern of the photomask shown in FIG. 1 is an octagonal band, but the present invention is not limited to this. The shape of the auxiliary pattern is preferably one in which a constant width is given to the shape of the rotation target having three-fold symmetry or more with respect to the center of the hole pattern. The preferred shapes of the main pattern and the auxiliary pattern are the shapes exemplified in FIGS. 2 (a) to 2 (f), and the design of the main pattern and the design of the auxiliary pattern are mutually shown in FIGS. 2 (a) to 2 (f). You may combine different ones.

For example, the case where the outer circumference 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. To. The shape of the auxiliary pattern is preferably such that the outer circumference and the inner circumference 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-shaped 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 surrounds the circumference 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 the same, it is easy to obtain the interaction of light 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 becomes an auxiliary pattern on the transferred object. It is possible to reduce the resist loss of the corresponding portion.

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

In addition to the main pattern and the auxiliary pattern of the present invention, other patterns may be additionally used as long as the effects of the present invention are not impaired.

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

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

In this photomask blank, a semitransparent film and a low translucent film are formed in this order on a transparent substrate made of glass or the like, and a first photoresist film is further applied.

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

It is desirable that the semipermeable membrane is made of a material that satisfies the above transmittance and phase difference and can be wet-etched as described below. However, if the amount of side etching generated during wet etching becomes too large, inconveniences such as deterioration of CD accuracy and destruction of the upper layer film due to undercut occur. Therefore, the film thickness range is preferably 2000 Å or less. For example, it is in the range of 300 to 2000 Å, more preferably 300 to 1800 Å. Here, CD is a Critical Dimension, and is used in the present specification to mean a pattern line width.

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

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

Considering the above properties, the film material of the translucent film includes at least one of Zr, Nb, Hf, Ta, Mo, and Ti and Si, or an oxide or nitride of these materials. , Oxidized nitrides, carbides, or materials containing carbided oxides.

A low permeable membrane is formed on the semipermeable membrane of the photomask blank. As a film forming method, a known means such as a sputtering method can be applied as in the case of a semipermeable membrane.

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

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 are the transmittance and the phase shift amount of the low transmissive portion of the photomask of the present invention. Is required to be able to achieve. Preferably, in the laminated state of the low translucent film and the semitransparent film, the transmittance T3 (%) with respect to the light of the exposure light representative wavelength is T3 <30, preferably T3 ≦ 20, and further, the phase shift. The amount φ3 is 90 (degrees) or less, more preferably 60 (degrees) or less.

The sole property of the low translucency film is that it does not substantially transmit light of the representative wavelength, or has a transmittance (T2 (%)) of less than 30 (%) (that is, 0 <. It is preferable that T2 <30) and the phase shift amount (φ2) are approximately 180 degrees. Approximately 180 degrees means 120 to 240 degrees. Preferably, the phase difference φ1 is 150 to 210 (degrees).

The material of the low translucency film of the photomask blank may be Cr or a compound thereof (oxide, nitride, carbide, carbide, or carbide oxide), or Mo, W, Ta, Ti. It may be a carboxyl of a metal containing the same, or the compound of the above. However, the material of the low-transmissive film of the photomask blank is preferably a material that can be wet-etched like the semipermeable membrane and has etching selectivity with respect to the material of the semipermeable membrane. That is, it is desirable that the low permeable membrane has resistance to the etching agent of the semipermeable membrane, and the semipermeable membrane has resistance to the etching agent of the low permeable membrane.

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

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

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

Next, as shown in FIG. 4D, the second photoresist film is applied to the entire surface including the formed low light-transmitting film pattern.

Next, as shown in FIG. 4 (e), a second drawing is performed on the second photoresist film to form a second resist pattern formed by development. Wet etching of the semipermeable membrane is performed using the second resist pattern and the low permeable membrane pattern as masks. By this etching (development), a region of the main pattern is formed, which is composed of a translucent portion that exposes the transparent substrate. The second resist pattern covers the region serving as the auxiliary pattern and has an opening in the region serving as the main pattern composed of the translucent portion, and the edge of the low translucent film is exposed from the opening. It is preferable to perform sizing on the drawing data of the second drawing. By doing so, it is possible to absorb the misalignment that occurs between the first drawing and the second drawing and prevent the CD accuracy of the transfer pattern from deteriorating. This is an effect of utilizing the etching selectivity of the materials of the low permeable membrane and the semipermeable membrane with respect to each other's films.

In the photomask of this embodiment, the semipermeable membrane and the low permeable membrane may be made of a material having common etching characteristics without etching selectivity, and an etching stopper film may be provided between the two films. good.

That is, by performing the sizing of the second resist pattern at the time of the second drawing in this way, when an attempt is made to form an isolated hole pattern on the transferred object, the patterning of the light-shielding film and the semipermeable membrane is displaced. Therefore, in the transfer pattern as illustrated in FIG. 1, the centers of gravity of the main pattern and the auxiliary pattern can be precisely matched.

The wet etchant for the semipermeable membrane is appropriately selected according to the composition of the semipermeable membrane.

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

In the production of a photomask for a display device, when patterning an optical film such as a light-shielding film formed on a transparent substrate, etchings applied include dry etching and wet etching. Either may be adopted, but wet etching is particularly advantageous in the present invention. This is because photomasks for display devices are relatively large in size, and there are many types of sizes. If dry etching using a vacuum chamber is applied in the production of such a photomask, inefficiency occurs in the size of the dry etching apparatus and the manufacturing process.

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

Further, when the film thickness F (nm) is large, the side etching amount is also large. Therefore, it is advantageous to use a film material having a phase shift amount of about 180 degrees even if the film thickness is small. It is desired that the refractive index of the semipermeable membrane is high with respect to the wavelength. Therefore, it is preferable to use a material having a wavelength of 1.5 to 2.9, preferably 1.8 to 2.4 with respect to the representative wavelength to form a semipermeable membrane.

By the way, as the photomask of the present invention shown in FIG. 1, in addition to the above aspects, there are those that exhibit the same optical action and effect by different layer configurations.

A second aspect of the present invention has a layer structure whose cross section is shown in FIG. 3 (b). The schematic plan view of this photomask is as shown in FIG. 1 as in the first aspect, but the laminated structure when viewed in cross section is different. That is, in the low translucent portion shown in FIG. 3B, the stacking order of the low transmissive film and the semipermeable membrane is upside down, and the low transmissive film is arranged on the substrate side.

In this case, the design of the pattern as the photomask of the present invention, its parameters, and the optical action and effect by them are the same as those of the photomask of the first aspect, and are shown in FIG. 2 as a design design. The same applies to the modification. Further, the physical characteristics of the film material used can be the same.

However, the photomask of the second aspect is slightly different from the first aspect in the manufacturing method in the following points, and therefore, the film material used is not necessarily the same as that of the first aspect. It doesn't have to be.

For example, in the first aspect, as shown in FIG. 4A, a photomask blank in which a semitransparent film and a low translucent film are laminated is prepared, and a photolithography step is applied to the photomask blank twice. Although a photomask has been manufactured, in the second aspect, it is necessary to prepare a photomask blank in which only a low light-transmitting film is formed on a transparent substrate.

Then, this low translucent film is first etched to form a low translucent film pattern. Next, a semipermeable membrane is formed on the entire surface of the substrate on which the low-permeable membrane pattern is formed, and the semipermeable membrane is patterned. In this case, it is preferable to select a material that can be patterned by wet etching as in the first aspect. However, in this embodiment, it is not essential that the low permeable membrane and the semipermeable membrane have resistance to each other's etchants. That is, both films can be etched even if they do not have etching selectivity. Therefore, there is a higher degree of freedom in selecting the material than in the first aspect.

Next, a third aspect of the photomask of the present invention will be described with reference to FIG. 3 (c). Also in this aspect, the schematic plan view is the same as that in FIG. 1, and the pattern design, its parameters, and the optical action and effect by them are the same as those of the photomask of the first aspect except for the following points. The same applies, and the modification shown in FIG. 2 can be applied as a design design.

The difference between the photomasks of the third aspect shown in FIG. 3C and the photomasks of the first and second aspects is that the amount of phase shift of the semipermeable membrane with respect to light of the representative wavelength is substantially the same. It is a point that is not restricted to 180 degrees, and in relation to this, a predetermined amount of transparent substrate is dug in the main pattern portion. That is, in the main pattern of this embodiment, instead of exposing a part of the main surface of the transparent substrate used as the material, the digging surface in which a predetermined amount of digging is formed by etching on the main surface is exposed. There is. Then, the phase difference of the representative wavelength in the wavelength range of the i-line to the g-line transmitted through each other between the auxiliary pattern in which the semipermeable membrane is formed and the main pattern in which the digging is formed is approximately 180. It is adjusted every time. Similar to the photomasks of the first and second aspects, the low transmissive portion includes a semi-transmissive film on a transparent substrate and a low transmissive film having a light transmittance of a representative wavelength of T2 (%). However, the structure can be laminated in this order or vice versa.

In the first aspect or the second aspect, the phase difference between the condition of the transmittance T1 and the representative wavelength transmitted between the main pattern and the auxiliary pattern is approximately 180 degrees depending on the material and the film thickness of the semitransparent film. It was necessary to satisfy both of the conditions, but in the photomask of the third aspect, the composition and film thickness of the semitransparent film were determined with priority given to the condition of transmittance T1, and the phase difference was adjusted. , There is an advantage that it can be done by the amount of digging of the main pattern.

From this point of view, in the photomask of this embodiment, the phase shift amount of the semipermeable membrane with respect to the light of the above representative wavelength may be 90 degrees or less, or 60 degrees or less. The phase difference of the representative wavelength transmitted through the main pattern and the auxiliary pattern may be adjusted to be approximately 180 degrees by the sum of the amount of digging of the main pattern and the amount of phase shift of the semipermeable membrane.

Further, in the photomask of the third aspect, wet or dry etching is used for digging and forming the transparent substrate, but dry etching is more preferably applied. Further, also in the photomask of this embodiment, an etching stopper film may be provided between the semipermeable membrane and the low permeable membrane.

For example, a photomask blank in which a semipermeable membrane and a low permeable membrane are laminated on a transparent substrate is prepared, first, both films of the main pattern portion are etched and removed, and then the transparent substrate is dug and etched. Applicable. Next, the photomask of the third aspect can be manufactured by etching and removing the low light-transmitting film of the auxiliary pattern portion by the second photolithography step. In this case, the film material can be the same as in the first aspect.

Similar to the relationship between the first aspect and the second aspect, in the photomask of the third aspect, the stacking order of the semipermeable membrane and the low permeable membrane may be reversed upside down.

Next, a fourth aspect of the photomask of the present invention will be described with reference to FIG. 3 (d). In this embodiment as well, the schematic plan view is as shown in FIG. In the fourth aspect, digging is formed in the transparent substrate of the main pattern portion as in the third aspect, but unlike the third aspect, the semipermeable membrane is not used and the transparent substrate of the auxiliary pattern portion is formed. (Part of the main surface) is exposed. Then, by selecting the digging depth of the main pattern portion, the phase difference of the light of the representative wavelength transmitted through the main pattern and the auxiliary pattern becomes approximately 180 degrees as in the first to third aspects. There is.

In this fourth aspect, since the semipermeable membrane is not present in the auxiliary pattern portion, the transmittance (T1) is 100 (%). In this case, the number of film formations can be reduced, and as a result, merits such as improvement of production efficiency and reduction of defect occurrence probability can be obtained from the third aspect.

すなわち、
０．５ ≦ ｄ ≦ １．５ ・・・（２）
となる。好ましくは、ｄ ＜ Ｗ１ である。 In this case, T1 = 100 (%) is applied to the equation (2).

That is,
0.5 ≤ d ≤ 1.5 ... (2)
Will be. Preferably, d <W1.

Further, the phase shift amount of the low translucent film used for the photomask of the fourth aspect with respect to the light of the representative wavelength does not have to be about 180 degrees, and is preferably 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 specified, 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 modification shown in FIG. 2 is applicable. Further, the film material used for the low translucent film and its physical properties can be the same as those in the first aspect. That is, the low translucent portion can have a structure in which a low translucent film having a light transmittance of the representative wavelength of T2 (%) (= T3 (%)) is formed on the transparent substrate. ..

By the way, in the fourth aspect, the cross-sectional structures of the main pattern and the auxiliary pattern are reversed in the fifth aspect (FIG. 3 (e)). 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 digging is formed on the main surface of the transparent substrate. That is, instead of digging the transparent substrate of the main pattern portion, by digging the transparent substrate of the auxiliary pattern portion, the phase difference of the light having the above representative wavelength transmitted through the main pattern and the auxiliary pattern is set to about 180 degrees. There is. Even in this case, it goes without saying that the design of the plan view and its optical action and effect are the same as those of the fourth aspect. In addition, there is no particular difference in the manufacturing method and the film material to be applied. Therefore, in the low translucency portion of the fifth aspect, a low translucency film having a light transmittance of a representative wavelength of T2 (%) (= T3 (%)) is formed on the 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 as represented by the configuration adopted in the first to fifth aspects (in FIG. 3 (f)). (Use the figure), showing the possibility of adding a light-shielding film pattern. This is worth considering when the low translucency film has substantial transmittance.

That is, in the vicinity of the main pattern and the auxiliary pattern, the interference action of light having opposite phases is used, but in the region of the low light-transmitting portion separated from the above, the presence of light transmitted through the low light-transmitting film is unnecessary. Or rather, there is a risk of bringing about the disadvantage of reducing the amount of residual film of the resist pattern formed on the transferred material. When it is desired to eliminate this risk, it is also useful to add a light-shielding film pattern to completely block light in the region of the low light-transmitting portion separated 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 its action and effect are not impaired. The light-shielding film refers to a film having an OD (optical density) of 2 or more that does not substantially transmit exposure light (light having a representative wavelength in the 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, which comprises a step of exposing the photomask of the present invention to the above-mentioned photomask of the present invention with an exposure apparatus, transferring the transfer pattern onto a transfer target, and forming a hole pattern. ..

In the method for manufacturing the display device of the present invention, first, the above-mentioned photomask of the present invention is prepared. Next, the transfer pattern is exposed using an exposure apparatus having a numerical aperture (NA) of 0.08 to 0.20 and having an exposure light source containing at least one of i-line, h-line, and g-line. A hole pattern having a diameter W2 of 3.0 μm or less, preferably 0.6 to 3.0 μm, is formed on the transferred body. The exposure light source of the exposure apparatus preferably includes i-line, h-line, and g-line. For the exposure, it is common and advantageous to apply the same magnification exposure.

Examples of the exposure machine used when transferring the transfer pattern using the photomask of the present invention include the following methods, which perform projection exposure at the same magnification. That is, it is an exposure machine used for LCD (liquid crystal display) (or for FPD, liquid crystal), and its configuration has a numerical aperture (NA) of 0.08 to 0.15 (coherence factor (coherence factor (coherence factor)). σ) is 0.4 to 0.9), and it has a light source (also referred to as a broad wavelength light source) that includes 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 present invention by applying the present invention even in an exposure apparatus in which the numerical aperture NA is 0.10 to 0.20.

Further, as the light source of the exposure apparatus to be used, deformed lighting (ring band lighting or the like) may be used, but the excellent effect of the invention can be obtained even with non-deformed lighting.

The present invention uses a semipermeable membrane and a low permeable membrane (and, if necessary, a light-shielding film) on a transparent substrate as raw materials for the photomask of the first to third aspects (and the sixth aspect to which the present invention is applied). ) Are laminated and a photomask blank is used. Then, a resist film is further applied and formed on the surface to manufacture a photomask.

The physical properties, film quality, and composition of the semipermeable membrane and the low permeable membrane are as described above.

That is, the semipermeable membrane of the photomask blank preferably has a transmittance T1 of 30 to 80 (%) with respect to a representative wavelength in the wavelength range of i-line to g-line. Further, the semipermeable membrane 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 semipermeable membrane having such a refractive index is sufficiently thin, it has a desired phase shift amount, so that the wet etching time of the semipermeable membrane can be shortened. As a result, side etching of the semipermeable membrane can be suppressed.

Further, in all aspects of the photomask of the present invention, it can be produced by using a photomask blank on which a low light-transmitting film is formed.

As the low translucency film, one that does not substantially transmit light of the representative wavelength or one having a transmittance of less than 30% can be used. Further, the phase shift amount of the low translucent film with respect to the representative wavelength in the i-line to g-line range is approximately 180 degrees in the photomasks according to the first and second aspects, and the third, fourth and fifth aspects. In the photomask according to the above, the temperature may be 90 degrees or less, more preferably 60 degrees or less.

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

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

(Comparative Example 1-2)
As shown in FIG. 5, the photomask of Comparative Example 1-2 is formed by patterning a semitransmissive film having an exposure light transmittance (against h line) of 5% and a phase shift amount of 180 degrees. Further, it is a halftone type phase shift mask having a main pattern composed of a rectangular translucent portion having a side (diameter) (that is, W1) of 2.0 (μm).

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

The auxiliary pattern assumes the photomask of the first aspect described above, in which a semipermeable membrane is formed on a transparent substrate. The exposure light (against h line) transmittance T1 of this semipermeable membrane is 70 (%), and the phase shift amount is 180 degrees. Further, the low light-transmitting portion surrounding the main pattern and the auxiliary pattern is made of a light-shielding film (OD> 2) that does not substantially transmit the exposure light.

In each of the photomasks of Comparative Examples 1-1 and 1-2 and Example 1, a diameter W2 of 2.0 μm (W1 = W2) is formed on the transferred body, that is, formed on the transferred body. The diameter W2 is the same as the diameter W1 of the main pattern of the transfer pattern of the photomask). The exposure conditions applied in the simulation are as follows. That is, the exposure light was a broad wavelength including i-line, h-line, and g-line, and the intensity ratio was 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 for obtaining the cross-sectional shape of the resist pattern formed on the transferred body was 1.5 μm.

The performance evaluation of each transfer pattern under the above conditions is shown in FIG. Further, FIG. 6 shows a spatial image of light intensity formed on the transferred body 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 through the photomask must have a good spatial image formed on the transferred object, that is, a profile of the transmitted light intensity curve. Specifically, the slope that forms the peak of transmitted light intensity is sharp and the rising direction is close to vertical, and the absolute value of the light intensity of the peak is high (when sub-peaks are formed in the surroundings). Is sufficiently high relative to its strength).

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

(1) Depth of focus (DOF)
The magnitude of the depth of focus to be within the range of ± 10% or more with respect to the target CD. When the value of DOF is high, it is not easily affected by the flatness of the transferred body (for example, a panel substrate for a display device), a fine pattern can be surely formed, and the variation in CD (line width) 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 transferred body, and the lower the MEEF, the more the CD error of the pattern formed on the transferred body can be reduced.

(3) Eop
Eop is a particularly important evaluation item in photomasks for manufacturing display devices. This is the amount of exposure light required to form the pattern size to be obtained on the transferred object. Since the photomask size is large in the manufacture of display devices (for example, a square or rectangle having a side of about 300 to 1400 mm on the main surface), it is possible to increase the speed of scan exposure by using a photomask having a low Eop value. , 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) of 55 μm or more, which is much larger than that of the comparative example. In that it is excellent, it shows stable transferability of the pattern. This means that the value of MEEF is small and the CD accuracy of a fine pattern is high.

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

Further, referring to the spatial image of the transmitted light intensity shown in FIG. 6, in the case of the photomask of Example 1, the peak of the main pattern portion is raised with respect to the threshold level (Eth) to which the resist is exposed. It can be seen that the inclination of the peak can be sufficiently raised (approaching perpendicular to the surface of the transferred object). This point is superior to Comparative Examples 1-1 and 1-2. Here, the increase in Eop and the decrease in MEEF are achieved by using the light transmitted through the auxiliary pattern to enhance the light intensity at the position of the main pattern. 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 Eth or less, there is no effect on the transfer of the main pattern.

A method for reducing the loss of the resist residual film derived from this side peak will be described below.

The design of the transfer pattern formed on the photomask was changed, and a simulation was performed using the samples shown in FIG. 7 (Comparative Example 2-1 and Comparative Example 2-2 and Example 2). Here, each sample was used. Both are 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 composed of a light-shielding film pattern formed on a transparent substrate. In the photomask of Comparative Example 2-1 the main pattern composed of the translucent portion where the transparent substrate is exposed is surrounded by the light-shielding portion. The diameter W1 (one side of the 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 semitransmissive film having an exposure light transmittance (against h line) of 5% and a phase shift amount of 180 degrees. Further, it is a halftone type phase shift mask having a main pattern composed of a quadrangular translucent portion having a diameter W1 (one side of a square) of the main pattern of 2.5 (μm).

(Example 2)
As shown in FIG. 7, the photomask of Example 2 is a transfer pattern of the present invention. The main pattern of the photomask of Example 2 is a square having a diameter W1 (one side of the square) of the main pattern of 2.5 (μm), and the auxiliary pattern is an octagonal band having a width d of 1.3 (μm). The pitch P, which is the distance between the center of the main pattern and the center of the width of the auxiliary pattern, is set to 4 (μm). Again, the photomask of Example 2 assumes the photomask of the first aspect.

Using the photomasks of Comparative Example 2-1 and Comparative Example 2-2 and Example 2, a hole pattern having a diameter of 2.0 μm is formed on the transferred object. That is, the mask bias (β = W1-W2) of these photomasks was set to 0.5 (μm). The exposure conditions applied in the simulation are 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, it showed advantageous performance over Comparative Examples 2-1 and 2-2 together with excellent DOF and MEEF. .. In the photomask of Example 2, the DOF is particularly a value exceeding 35 μm.

Further, by 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 transferred body, the excellent characteristics of the sample of Example 2 become clear. As shown in FIG. 8, when the photomask of Example 2 is used, the peak corresponding to the main pattern is much higher than the side peaks 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 range of 0.2 to 1.0 (μm). It has been clarified that an excellent transfer image that is easier to use for practical use can be obtained in a certain transfer pattern.

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

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 in the manufacture of a display device including a liquid crystal display device, an EL display device, and the like.

According to the photomask of the present invention, mutual interference of exposure light transmitted through both the main pattern and the auxiliary pattern is controlled, the zero-order light is reduced during exposure, and the ratio of ± primary light is relatively increased. Can be done. Therefore, the spatial image of transmitted light can be significantly improved.

It is advantageous to use the photomask of the present invention for forming an isolated hole pattern such as a contact hole often used in a liquid crystal display or an EL device as an application in which such an action and effect can be advantageously obtained. As for the types of patterns, a dense pattern in which a large number of patterns are arranged with a certain regularity and these have an optical influence on each other, and an isolation pattern in which such a regular arrangement pattern does not exist in the surroundings. Often referred to as a distinction from the pattern. The photomask of the present invention is suitably applied when an isolated pattern is to be formed on a transferred body.

An additional optical film or functional film may be used for the photomask of the present invention as long as the effects of the present invention are not impaired. For example, in order to prevent the inconvenience that the light transmittance of the low light transmittance film interferes with the inspection and the position detection of the photomask, a light shielding film may be formed in a region other than the transfer pattern. Further, in the semipermeable membrane, an antireflection layer for reducing reflection of drawing light or exposure light may be provided on the surface thereof.

Claims (6)

A photomask for manufacturing a display device having a transfer pattern formed on a transparent substrate, for forming a hole pattern on a transfer target by exposure using an exposure device for the display device. In the photomask
The transfer pattern is
The main pattern with a diameter of W1 (μm) and
An auxiliary pattern having a width of d (μm) arranged in the vicinity of the main pattern and an auxiliary pattern having a width of d (μm).
It has a low light-transmitting portion that constitutes a region other than the main pattern and the auxiliary pattern being formed.
The phase difference of the light transmitted through the main pattern and the auxiliary pattern is approximately 180 degrees with respect to the light having a representative wavelength within the wavelength range of the i-line to the g-line.
When the transmittance of light of the representative wavelength transmitted through the auxiliary pattern is T1 (%), the following equations (1), (2) and (5) are satisfied.
The shape of the auxiliary pattern is a regular polygonal band or a circular band surrounding the main pattern, or a shape in which a part of the polygonal band or the circular band is missing and.
The transfer pattern is characterized in that the DOF is increased as compared with the case where the auxiliary pattern is not provided by controlling the interference between the main pattern and the light transmitted through the auxiliary pattern. , Photomask.
0.8 ≤ W1 ≤ 4.0 ... (1)

30 ≤ T1 ≤ 80 ... (5) The photomask according to claim 1, wherein 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 formula (3) is satisfied.
1.0 <P ≤ 5.0 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ (3) 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 semipermeable membrane having a transmittance of T1 (%) for light of the representative wavelength on the transparent substrate.
In the low translucency portion, the semitransparent film and the low translucent film having a light transmittance of the representative wavelength of T2 (%) are arranged on the transparent substrate in this order or vice versa. The photomask according to claim 1 or 2, wherein the photomasks are laminated in the order of. The width d (μm) of the auxiliary pattern is
d ≧ 0.7 μm
The photomask according to any one of claims 1 to 3, wherein the photomask is characterized by the above. Claims 1 to 1, characterized in that a hole pattern having a transfer diameter W2 of 3.0 (μm) or less (however, W1> W2) is formed on the transferred body corresponding to the main pattern. The photomask according to any one of 4. When the difference W1-W2 between the diameter W1 of the main pattern and the transfer diameter W2 on the transferred body is defined as the bias β (μm),
0.2 ≤ β ≤ 1.0 ... (6)
The photomask according to any one of claims 1 to 5, wherein the photomask is characterized by the above.

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