JP7231667B2 - Photomask blank for manufacturing display device, photomask for manufacturing display device, and method for manufacturing display device - Google Patents

Description

The present invention relates to a photomask that is advantageously used in the manufacture of display devices such as liquid crystal and organic EL, and a method of manufacturing the 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 parallel to each side of a 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 in the portion is inverted.

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

JP-A-3-15845 JP 2013-148892 A

2. Description of the Related Art Currently, display devices including liquid crystal display devices and EL display devices are desired to be brighter, consume less power, and have improved display performance such as high definition, high-speed display, and a wide viewing angle.

For example, in the case of a thin film transistor ("TFT") used in the display device, among the plurality of patterns that constitute the TFT, the contact holes formed in the interlayer insulating film are reliably aligned with the upper and lower patterns. Correct operation cannot be guaranteed unless it has the function of connecting the On the other hand, in order to increase the aperture ratio of the display device as much as possible and 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 be made finer (for example, less than 3 μm). For example, a hole pattern with a diameter of 2.5 μm or less, furthermore, a diameter of 2.0 μm or less will be required, and in the near future, formation of a pattern with a diameter of 1.5 μm or less, which is smaller than this, will be desired. Against this background, there is a need for a manufacturing technique for display devices that enables reliable transfer of minute contact holes.

By the way, in the field of photomasks for manufacturing semiconductor devices (LSI), where the degree of integration is higher than that of display devices and the miniaturization of patterns has progressed remarkably, high NA is required for exposure devices in order to obtain high resolution. (e.g., 0.2 or more) is applied to the exposure light, and there is a history of shortening the wavelength of the exposure light. Became.

On the other hand, in the field of lithography for manufacturing display devices, it has not been common to apply the above method for improving resolution. Rather, the NA of an exposure apparatus known for LCD (liquid crystal display) is about 0.08 to 0.10, and the exposure light source also has a broad wavelength including i-line, h-line, and g-line. By using a wide range, there has been 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 before. Here, there are some problems in applying the technology for semiconductor device manufacturing as it is to display device manufacturing. For example, switching to a high-resolution exposure apparatus with a high NA (numerical aperture) requires a large investment, which cannot be matched with the price of the display apparatus. Alternatively, changing the exposure wavelength (using a short wavelength such as an ArF excimer laser at a single wavelength) is difficult to apply to a display device having a large area. It is inconvenient in that not only does it decrease, but it also requires a considerable investment.

Furthermore, as will be described later, photomasks for display devices have manufacturing restrictions and various unique problems that differ from photomasks for manufacturing semiconductor devices.

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

Therefore, in a method of 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 an object to be transferred. SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an excellent photomask which is advantageously adapted to the exposure environment of a mask for manufacturing a display device and capable of stably transferring a fine pattern, and a method of manufacturing the same.

In order to solve the above problems, the present invention has the following configurations. The present invention provides a photomask characterized by the following structures 1 to 14, and a display device manufacturing method characterized by the following structure 15.

１．０ ＜ Ｐ ≦ ５．０ ・・・・・・・・・・・・・・・（３）
Ｔ３ ＜ Ｔ１ ・・・・・・・・・・・・・・・・・・・・・（４） (Configuration 1)
Configuration 1 of the present invention is a photomask provided with a transfer pattern formed on a transparent substrate, wherein the transfer pattern includes a main pattern having a diameter of W1 (μm) and arranged in the vicinity of the main pattern. , an auxiliary pattern with a width d (μm), and a low light-transmitting portion disposed in a region other than the main pattern and the auxiliary pattern, i-line to g-line passing through the main pattern 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 defined as T1 (%). , where T3 (%) is the transmittance of the light of the representative wavelength that is transmitted through the low light-transmitting portion, and P (μm) is the distance between the center of the main pattern and the center of the auxiliary pattern in the width direction. , and a photomask that satisfies the following formulas (1) to (4).
0.8 ≤ W1 ≤ 4.0 (1)

1.0 < P ≤ 5.0 (3)
T3<T1 (4)

(Configuration 2)
Configuration 2 of the present invention is characterized in that the auxiliary pattern is formed by forming a semi-transparent film having a transmittance of T1 (%) for light of the representative wavelength on the transparent substrate. It is the described photomask.

(Composition 3)
Structure 3 of the present invention is the photomask according to Structure 2, wherein the transmittance T1 (%) of the semitransparent film satisfies the following formula (5).
30 ≤ T1 ≤ 80 (5)

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

(Composition 5)
In a fifth aspect 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 semitransparent film on the transparent substrate, and the The low light-transmitting portion comprises the semi-light-transmitting film and the low light-transmitting film having a transmittance of T2 (%) for light of the representative wavelength on the transparent substrate in this order, or vice versa. 5. The photomask according to any one of Structures 2 to 4, which is laminated in order.

(Composition 6)
In a sixth aspect of the present invention, the main pattern is formed by engraving the main surface of the transparent substrate, the auxiliary pattern is formed by forming the semitransparent film on the transparent substrate, and the The low light-transmitting portion comprises the semi-light-transmitting film and the low light-transmitting film having a transmittance of T2 (%) for light of the representative wavelength on the transparent substrate in this order, or vice versa. 5. The photomask according to any one of Structures 2 to 4, which is laminated in order.

(Composition 7)
In a seventh aspect of the present invention, the semitransparent film is a material containing at least one of Zr, Nb, Hf, Ta, Mo and Ti and Si, or an oxide, nitride, or oxynitride of these materials. 7. The photomask according to any one of Structures 2 to 6, wherein the photomask is made of a material containing a compound, a carbide, or a carbide oxynitride.

(Composition 8)
A configuration 8 of the present invention is the photomask according to the configuration 1, wherein the auxiliary pattern is formed by exposing the transparent substrate.

(Composition 9)
In a ninth aspect of the present invention, the main pattern is formed by engraving the main surface of the transparent substrate, and the auxiliary pattern is formed by exposing a part of the main surface of the transparent substrate. The photomask according to Structure 8, wherein the light portion is formed on the transparent substrate with a low light-transmitting film having a transmittance of T3 (%) for light of the representative wavelength. is.

(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 engraving the main surface of the transparent substrate, and the low-permeability The photomask according to Structure 8, wherein the light portion is formed on the transparent substrate with a low light-transmitting film having a transmittance of T3 (%) for light of the representative wavelength. is.

(Composition 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 (where W1>W2) is formed on the transferred body corresponding to the main pattern. The photomask according to any one of Structures 1 to 10, wherein

(Composition 12)
In a twelfth aspect 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 material is a bias β (μm),
0.2≤β≤1.0 (6)
The photomask according to Structure 11, characterized in that:

(Composition 13)
In configuration 13 of the present invention, the transmittance T3 (%) of the low light-transmitting portion for light of the representative wavelength is
T3<30 (7)
13. The photomask according to any one of Structures 1 to 12, wherein:

(Composition 14)
Structure 14 of the present invention is the photomask according to any one of Structures 1 to 12, wherein the low light-transmitting portion substantially does not transmit light of the representative wavelength.

(Composition 15)
Structure 15 of the present invention includes a step of preparing a photomask according to any one of Structures 1 to 14, and having a numerical aperture (NA) of 0.08 to 0.20, i-line, h-line and g-line a step of exposing the transfer pattern using an exposure device having an exposure light source including at least one to form a hole pattern having a diameter W2 of 0.6 to 3.0 (μm) on the transferred body; A method of manufacturing a display device, comprising:

According to the present invention, it is possible to provide an excellent photomask which is advantageously adapted to the exposure environment of the mask for manufacturing display devices and which enables stable transfer of a fine pattern, and a method for manufacturing the same.

1 is a schematic plan view of an example of a photomask of the present invention; FIG. 3A to 3F are schematic plan views of other examples of the photomask of the present invention. FIG. 3 shows examples (a) to (f) of the layer structure of the photomask of the present invention. It is a cross-sectional schematic diagram and a plane schematic diagram which show an example of the manufacturing process of the photomask of this invention. FIG. 2 is a schematic plan view of photomasks of Comparative Examples 1-1 and 1-2 and Example 1, dimensions, and diagrams showing transfer performance by optical simulation. When using the photomasks of Comparative Examples 1-1 and 1-2 and Example 1, (a) a light intensity aerial image formed on the transfer target, and (b) a resist pattern formed thereby. It is a figure which shows a cross-sectional shape. FIG. 10 is a schematic plan view of photomasks of Comparative Examples 2-1 and 2-2 and Example 2, dimensions, and diagrams showing transfer performance by optical simulation; When the photomasks of Comparative Examples 2-1 and 2-2 and Example 2 were used, (a) the aerial image of the light intensity formed on the transfer target, and (b) the resist pattern formed thereby. It is a figure which shows a cross-sectional shape.

When the CD (Critical Dimension, hereinafter referred to as the pattern line width) of the transfer pattern of the photomask becomes finer, it can be precisely applied to the object to be transferred (thin film to be etched, etc., also called object to be processed). It becomes more difficult to carry out the step of transferring to In many cases, the resolution limit indicated as a specification for exposure devices for display devices is about 2 to 3 μm. On the other hand, among the transfer patterns to be formed, there have already appeared those having dimensions close to or smaller than this. Furthermore, since a mask for manufacturing a display device has a larger area than 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.

Therefore, it is necessary to draw 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).

Furthermore, since the area of the transfer target (flat panel display substrate) is large, it can be said that in the process of pattern transfer by exposure, defocusing due to the surface flatness of the transfer target is likely to occur. In this environment, it is extremely significant to ensure sufficient latitude of focus (DOF) during exposure.

As is well known, photomasks for manufacturing display devices are large in size, and in wet processing (development and wet etching) in the photomask manufacturing process, uniformity of CD (line width) is required 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 essential to ensure a sufficient depth of focus (DOF) in the exposure process, and it is desirable that other performances do not deteriorate along with this. .

The present invention is a photomask provided with a transfer pattern formed by patterning a semi-transparent film and a low-translucent film formed on a transparent substrate. FIG. 1 shows a schematic plan view of the transfer pattern of the photomask of the present invention.

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

１．０ ＜ Ｐ ≦ ５．０ ・・・・・・・・・・・・・・・（３）
Ｔ３ ＜ Ｔ１ ・・・・・・・・・・・・・・・・・・・・・（４） Here, let T1 be the transmittance of the light of the representative wavelength within the wavelength range of the i-line to the g-line, which is transmitted through the auxiliary pattern, and T3 be the transmittance of the light of the representative wavelength, which is transmitted through the low light-transmitting portion. Also, let P (μm) be the distance between the center of the main pattern and the center of the auxiliary pattern in the width direction. At this time, the photomask of the present invention satisfies the following relationships.
0.8 ≤ W1 ≤ 4.0 (1)

1.0 < P ≤ 5.0 (3)
T3<T1 (4)

In the above formula, T1 preferably satisfies 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, for example, shown in FIG. This will be described as a first mode of the photomask of the present invention with reference to FIG. 3(a).

In this aspect, the main pattern is made up of the translucent part where the transparent substrate is exposed. A film having a high transmittance may be formed on the main pattern. However, in order to obtain the maximum transmittance, it is preferable that the transparent substrate is exposed without forming a film having a high transmittance on the main pattern.

Further, the auxiliary pattern of this aspect is composed of a semi-transparent portion in which a semi-transparent film is formed on a transparent substrate. This semitransparent film has a phase shift amount that shifts the light of the representative wavelength in the wavelength range of i-line to g-line by approximately 180 degrees, and has a transmittance T1 (%) for the representative wavelength. A portion surrounding the main pattern and the auxiliary pattern is a low light-transmitting portion in which at least a low light-transmitting film is formed on a transparent substrate. That is, in the transfer pattern shown in FIG. 1, the areas other than the areas where the main pattern and the auxiliary pattern are formed are the low light-transmitting portions. As shown in FIG. 3A, in this aspect, the low light-transmitting portion is formed by laminating a semi-transparent film and a low light-transmitting film on the transparent substrate. Note that the low light-transmitting portion is a semi-light-transmitting film and a low light-transmitting film having a transmittance of T2 (%) for light of a representative wavelength on a transparent substrate, in this order, or in reverse order. can be laminated with

The low light-transmitting 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, for light of a representative wavelength in the wavelength range of i-line to g-line, the low light-transmitting portion has a transmittance T3 (%) lower than the transmittance T1 (%) of the auxiliary pattern composed of the semi-transparent portion. Have. Therefore, in this embodiment (FIG. 3(a)) in which the low light-transmitting portion is formed by stacking the semi-light-transmitting portion and the low light-transmitting portion, the stacking provides:
T3 < T1
By selecting the transmittance T2 (%) of the low light-transmitting film, the transmittance T3 (%) of the low light-transmitting portion may be adjusted so that .

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

Specifically, W1 (μm) is expressed by the following formula (1)
0.8≦W1≦4.0 (1)
It is preferable to have a relationship of At this time, the diameter W2 (μm) of the main pattern (hole pattern) formed on the transferred material is 3.0 (μm) or less.
0.6≤W2≤3.0
can be

In addition, the photomask of the present invention can be used for the purpose of forming fine-sized patterns useful for manufacturing display devices. 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 significantly. Preferably, the diameter W1 (μm) of the main pattern is
1.0≤W1≤3.0
can be The relationship between the diameter W1 and the diameter W2 can be W1=W2, but preferably 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 When doing so, as will be described later, advantageous effects such as reduction of 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 approximated thereto. For example, when the shape of the main pattern is a regular polygon, the diameter W1 of the main pattern is the diameter of the inscribed circle. If the shape of the main pattern is a square as shown in FIG. 1, the diameter W1 of the main pattern is the length of one side. The diameter W2 of the transferred main pattern is also the same in that it is the diameter of a circle or a numerical value approximated to it.

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

The preferred ranges for setting the diameter W1 of the main pattern in the photomask of the present invention, the diameter W2 of the main pattern on the transfer target, and the bias are the following second to sixth aspects of the present invention. A photomask can be similarly applied.

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 of the representative wavelength that is transmitted through the main pattern and the light of the representative wavelength that is transmitted through the auxiliary pattern is approximately 180 degrees. Approximately 180 degrees means 120 to 240 degrees. Preferably, the phase difference φ1 is 150-210 degrees.

The photomask of the present invention exhibits a remarkable effect when exposure light containing i-line, h-line or g-line is used. can be used. In particular, broad wavelength light including i-line, h-line and g-line is preferably applied as exposure light. In this case, any one of the i-line, h-line, and g-line can be used as the representative wavelength. For example, the photomask of the present invention can be constructed using the h-line as a representative wavelength.

In order to form such a phase difference, the main pattern is a light-transmitting portion formed by exposing the main surface of the transparent substrate, and the auxiliary pattern is a semi-transmitting portion formed by forming a semi-transmitting film on the transparent substrate. , and the phase shift amount of the semitransparent film with respect to the representative wavelength should be approximately 180 degrees.

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 are also applicable to the photomasks of the present invention according to the following second to sixth aspects. , and so on.

In the photomask of the first mode, that is, the photomask shown in FIG. 3A, the light transmittance T1 of the semi-transparent portion can be set as follows. That is, when the transmittance of the semi-transparent film formed in the semi-transparent portion with respect to the representative wavelength is T1 (%),
30 ≤ T1 ≤ 80
and More preferably
40 ≤ T1 ≤ 75
is. The transmittance T1 (%) is the transmittance of the representative wavelength when the transmittance of the 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 the region where the main pattern and the auxiliary pattern are formed and formed around the main pattern and the auxiliary pattern can have the following configuration. .

The low translucent portion may substantially not transmit exposure light (light of a representative wavelength within 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 representative wavelength (that is, a light-shielding film) and has T3≦0.01, that is, optical density OD≧2, is applied. Alternatively, a laminated film of a low light-transmitting film and a semi-light-transmitting film may be used as a substantial light shielding film.

Alternatively, the low light transmission portion may transmit the exposure light within a predetermined range. However, when the exposure light is transmitted in a predetermined range, the transmittance T3 (%) of the low light-transmitting portion (here, in the case of a laminate of a semi-transparent film and a low light-transmitting film, transmittance) is
T3 < T1
It satisfies Preferably,
0≦T3<30
More preferably
0 < T3 ≤ 20
meet. The transmittance T3 (%) is also the transmittance of the representative wavelength when the transmittance of the transparent substrate is used as a reference.

Further, when the low light-transmitting portion transmits the exposure light with a predetermined transmittance, the phase difference φ3 between the light transmitted through the low light-transmitting portion and the light transmitted through the light-transmitting portion should be 90 degrees or less. 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 a phase difference with respect to the representative wavelength contained in the exposure light.

Therefore, in this case, the single property of the low light-transmitting film used in the photomask of this embodiment is to have a transmittance (T2(%)) of less than 30(%) (that is, 0<T2<30). , the phase shift amount (φ2) is preferably approximately 180 degrees. Approximately 180 degrees means 120 to 240 degrees. Preferably, the phase difference φ1 is 150-210 degrees. As a result, φ3 can be set within the range described above for the phase shift characteristics of the low light-transmitting portion formed by lamination.

The transmittance here is also the transmittance of the representative wavelength when the transmittance of the transparent substrate is used as a reference, as in the above case.

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

The excellent effect of the invention can be obtained when At this time, the distance between the center of the main pattern and the center of the auxiliary pattern in the width direction is defined as a 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 effect like a pseudo-dense pattern on the main pattern, which is isolated in design. The exposure light that has passed through the pattern and the auxiliary pattern interacts well with each other, and can exhibit excellent transferability as shown in Examples below.

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.

Further, it is preferable that d≦W1, and more preferably d<W1.

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

As mentioned above, the main pattern of the photomask shown in FIG. 1 is square, but the invention is not so limited. For example, as illustrated in FIG. 2, the main pattern of the photomask can be a rotationally symmetrical shape, including octagons and circles. The center of rotational symmetry can be used as the reference center for P.

Moreover, although the shape of the auxiliary pattern of the photomask shown in FIG. 1 is an octagonal band, the present invention is not limited to this. The shape of the auxiliary pattern is preferably a shape that is rotationally symmetrical with respect to the center of the hole pattern and is symmetrical about three or more times with a certain width. Preferred shapes of the main pattern and auxiliary pattern are the shapes illustrated in FIGS. may be combined.

For example, the outer circumference of the auxiliary pattern is a regular polygon (preferably a regular 2n-sided polygon, where n is an integer of 2 or more) such as a square, regular hexagon, regular octagon, regular 10-sided polygon, or circular. be. As for the shape of the auxiliary pattern, it is preferable that the outer circumference and the inner circumference of the auxiliary pattern are substantially parallel to each other, that is, a regular polygonal or circular belt-like shape having a substantially constant width. This belt-like shape is also called a polygonal belt or a circular belt. As for the shape of the auxiliary pattern, it is preferable that such a regular polygon band or a circular band surround the main pattern. At this time, since the balance of the amount of light transmitted through the main pattern and the amount of light transmitted through the auxiliary pattern can be made substantially equal, it is easy to obtain the light interaction for obtaining the effects 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, the auxiliary pattern is formed on the transfer target. 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 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 a quadrangular band are missing, as shown in FIG. 2(f).

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

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

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

This photomask blank has a semi-transparent film and a low-transparent film formed in this order on a transparent substrate made of glass or the like, and further coated with a first photoresist film.

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

The semitransparent film preferably satisfies the above transmittance and phase difference and is made of a material that can be wet-etched as described below. However, if the amount of side etching that occurs during wet etching becomes too large, problems such as deterioration of CD precision and destruction of the upper layer film due to undercut will occur. For example, the range is 300-2000 Å, more preferably 300-1800 Å. Here, CD stands for Critical Dimension, and is used in this specification to mean pattern line width.

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

Furthermore, in order to fully exhibit the phase shift effect, it is preferable that the wet etching pattern cross section (etched surface) is nearly perpendicular to the main surface of the transparent substrate.

Considering the above properties, the film material for the semitransparent film is a material containing at least one of Zr, Nb, Hf, Ta, Mo, and Ti and Si, or an oxide or nitride of these materials. , oxynitrides, carbides, or oxynitride carbides.

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

The low light-transmitting film of the photomask blank can 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 light-transmitting film used for manufacturing the photomask of the present invention has a transmittance T2 ( %).

When the low light-transmitting film can transmit exposure light, the transmittance and phase shift amount of the low light-transmitting film with respect to the exposure light are the transmittance and phase shift amount of the low light-transmitting portion of the photomask of the present invention. It is required to be able to achieve Preferably, in the laminated state of the low light-transmitting film and the semi-transmitting film, the transmittance T3 (%) with respect to the light of the representative wavelength of the exposure light satisfies T3<30, preferably T3≦20, and further, the phase shift The amount φ3 is set to 90 (degrees) or less, more preferably 60 (degrees) or less.

The single property of the low translucent 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 < T2<30), and the phase shift amount (φ2) is preferably approximately 180 degrees. Approximately 180 degrees means 120 to 240 degrees. Preferably, the phase difference φ1 is 150-210 (degrees).

The material of the low translucent film of the photomask blank may be Cr or its compounds (oxide, nitride, carbide, oxynitride, or oxynitride carbide), or Mo, W, Ta, Ti. It may be a silicide of the containing metal or the above compound of the silicide. However, the material of the low translucent film of the photomask blank is preferably a material that can be wet-etched in the same manner as the semi-translucent film and has etching selectivity with respect to the material of the semi-translucent film. That is, it is desirable that the low translucent film has resistance to the etchant for the semitranslucent film, and that the semitranslucent film has resistance to the etchant for the low translucent film.

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, the photoresist suitable for it is used. The first photoresist film may be either positive type or negative type, but the positive type will be described below.

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

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

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

Next, as shown in FIG. 4E, a second drawing is performed on the second photoresist film to form a second resist pattern formed by development. Using the second resist pattern and the low light-transmitting film pattern as a mask, the semi-transparent film is wet-etched. This etching (development) forms the main pattern area, which consists of the translucent portion where the transparent substrate is exposed. The second resist pattern covers the area to be the auxiliary pattern and has an opening in the area to be the main pattern consisting of the light-transmitting portion. It is preferable to perform sizing on the drawing data for 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 deterioration of the CD accuracy of the transfer pattern. This is the effect of utilizing the etching selectivity of the materials of the low translucent film and the semi-translucent film with respect to each other.

In the photomask of this aspect, the semi-transparent film and the low-translucent film may be made of a material having no etching selectivity and common etching characteristics, and an etching stopper film may be provided between the two films. good.

That is, by performing the sizing of the second resist pattern in the second drawing in this way, when an isolated hole pattern is to be formed on the object to be transferred, the patterning of the light-shielding film and the semi-transparent film may be misaligned. Therefore, in the transfer pattern shown in FIG. 1, the centers of gravity of the main pattern and the auxiliary pattern can be matched precisely.

A wet etchant for the semi-transparent film is appropriately selected according to the composition of the semi-transparent film.

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

In the manufacture of photomasks for display devices, dry etching and wet etching are used for patterning an optical film such as a light shielding film formed on a transparent substrate. Either method may be used, but wet etching is particularly advantageous in the present invention. This is because photomasks for display devices are relatively large in size and have a wide variety of sizes. If dry etching using a vacuum chamber is applied in manufacturing such a photomask, inefficiency will occur in the size of the dry etching apparatus and in the manufacturing process.

However, there are also challenges associated with applying wet etching during the fabrication of such photomasks. Since wet etching has the property of isotropic etching, when a predetermined film is etched in the depth direction to be eluted, the etching progresses also in the direction perpendicular to the depth direction. For example, when a slit is formed by etching a semi-transparent film having a thickness of F (nm), the opening of the resist pattern serving as an etching mask is 2F (nm) from the desired slit width (that is, F (nm) on one side). ), 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 to set the width d of the auxiliary pattern to 1 (μm) or more, preferably 1.3 (μm) or more.

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

By the way, as the photomask of the present invention shown in FIG. 1, there is a photomask other than the above-described mode that has the same optical action and effect due to a different layer structure.

A second embodiment 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, similarly to the first mode, but the layered structure when viewed in cross section is different. That is, in the low light-transmitting portion shown in FIG. 3B, the lamination order of the low light-transmitting film and the semi-transparent film is reversed, and the low light-transmitting film is arranged on the substrate side.

In this case, as the photomask of the present invention, the pattern design, its parameters, and the optical effects thereof are the same as those of the photomask of the first embodiment, and the design design is shown in FIG. It is the same that modifications are applicable. Also, the physical properties of the film materials used can be the same.

However, in the photomask of the second mode, there are some differences from the first mode in the following points in terms of the manufacturing method. does not have to be

For example, in the first embodiment, as shown in FIG. 4A, a photomask blank in which a semi-transparent film and a low-translucent film are laminated is prepared, and the photolithography process is applied twice to this, A photomask has been manufactured, but in the second aspect, it is necessary to prepare a photomask blank in which only a low translucent film is deposited on a transparent substrate.

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

Next, a third embodiment of the photomask of the present invention will be described with reference to FIG. 3(c). Also in this embodiment, the schematic plan view is the same as that of FIG. It is the same, and it is also the same that the modification shown in FIG. 2 can be applied as a design design.

The photomask of the third mode shown in FIG. 3C is different from the photomasks of the first and second modes in that the phase shift amount of the semitransparent film with respect to the light of the representative wavelength is approximately This is not restricted to 180 degrees, and related to this is that the transparent substrate is recessed by a predetermined amount in the main pattern portion. That is, in the main pattern of this aspect, instead of partially exposing the main surface of the transparent substrate as a material, a carved surface formed by etching the main surface to a predetermined amount is exposed. there is The phase difference between the auxiliary pattern formed with the semi-transparent film and the main pattern formed with the engraving is approximately 180 between representative wavelengths in the wavelength range of i-line to g-line that transmit each other. adjusted to the degree. As in the photomasks of the first and second aspects, the low light-transmitting portion includes a semi-transparent film and a low light-transmitting film having a transmittance of T2 (%) for light at a representative wavelength on a transparent substrate. are stacked in this order or in the reverse order.

In the first aspect or the second aspect, depending on the material and film thickness of the semi-transparent film, the transmittance T1 condition and the phase difference between the representative wavelengths that transmit the main pattern and the auxiliary pattern are approximately 180 degrees. However, in the photomask of the third aspect, the composition and film thickness of the semitransparent film are determined with priority given to the condition of the transmittance T1, and the phase difference is adjusted. , there is an advantage that it can be performed depending on the depth of the main pattern.

From this point, in the photomask of this aspect, the phase shift amount of the semitransparent film with respect to the light of the representative wavelength may be 90 degrees or less, or 60 degrees or less. The sum of the amount of engraving of the main pattern and the amount of phase shift of the semitransparent film may be adjusted so that the phase difference between the representative wavelengths transmitted through the main pattern and the auxiliary pattern is approximately 180 degrees.

In addition, in the photomask of the third aspect, wet or dry etching is used for digging the transparent substrate, and dry etching is more preferably applied. Also in the photomask of this mode, an etching stopper film may be provided between the semi-transparent film and the low-translucent film.

For example, there is a process of preparing a photomask blank in which a semi-transparent film and a low-translucent film are laminated on a transparent substrate, first removing both films from the main pattern portion by etching, and then digging and etching the transparent substrate. Applicable. Next, the photomask of the third aspect can be manufactured by etching away the low light-transmitting film in the auxiliary pattern portion by a second photolithography process. In this case, the film material may be the same as in the first mode.

As in the relationship between the first mode and the second mode, also in the photomask of the third mode, the stacking order of the semi-transparent film and the low-translucent film may be reversed.

Next, a fourth aspect of the photomask of the present invention will be described with reference to FIG. 3(d). A schematic plan view of this embodiment is also shown in FIG. In the fourth mode, a recess is formed in the transparent substrate of the main pattern portion similarly to the third mode, but unlike the third mode, a semitransparent film 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 depth of engraving in the main pattern portion, the phase difference between the light of the representative wavelength that passes through the main pattern and the auxiliary pattern becomes approximately 180 degrees, as in the first to third modes. there is

In the fourth mode, since there is no semi-transparent film in the auxiliary pattern portion, the transmittance (T1) is 100(%). In this case, the number of times of film formation can be reduced, thereby obtaining advantages such as an improvement in production efficiency and a reduction in the probability of occurrence of defects as compared with the third mode.

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 formula (2),

i.e.
0.5≦d≦1.5 (2)
becomes. Preferably, d<W1.

Further, the phase shift amount of the light of the representative wavelength, which the low light-transmitting film used for the photomask of the fourth aspect has, need not be approximately 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 pattern design shown in FIG. , the modifications shown in FIG. 2 are also applicable. Also, the film material and physical properties used for the low translucent film can be the same as in the first mode. That is, the low light-transmitting portion can have a structure in which a low light-transmitting film having a transmittance of T2(%) (=T3(%)) for light of the representative wavelength is formed on a transparent substrate. .

By the way, the fifth mode (FIG. 3(e)) is obtained by reversing the cross-sectional structures of the main pattern and the auxiliary pattern in the fourth mode. The main pattern of the fifth aspect exposes a portion of the main surface of the transparent substrate, and the auxiliary pattern is formed by engraving the main surface of the transparent substrate. That is, instead of digging the transparent substrate in the main pattern portion, by digging the transparent substrate in the auxiliary pattern portion, the phase difference of the light of the representative wavelength, which is transmitted through the main pattern and the auxiliary pattern, is set to approximately 180 degrees. there is Even in this case, it goes without saying that the plan view design and its optical effects are the same as those of the fourth aspect. Moreover, there is no particular difference in the manufacturing method, the film material to be applied, and the like. Therefore, in the low light-transmitting portion of the fifth aspect, a low light-transmitting film having a transmittance of T2(%) (=T3(%)) for light of the representative wavelength is formed on the transparent substrate.

The sixth aspect of the present invention shown in FIG. ), which shows the possibility of adding a light-shielding film pattern. This is worth considering if the low transmissive film has substantial transmittance.

In other words, in the vicinity of the main pattern and the auxiliary pattern, the interference effect of light of opposite phases is used, but in the region of the low light-transmitting portion away from the above, there is no need for light to pass through the low light-transmitting film. Or rather, there is a risk of bringing about the demerit of reducing the residual film amount of the resist pattern formed on the transferred body. If it is desired to eliminate this risk, it is useful to add a light-shielding film pattern to the region of the low light-transmitting portion separated from the main pattern and the auxiliary pattern to completely shield the light.

Therefore, in the present invention, the use of such a light-shielding film pattern is not prohibited as long as the effects are not impaired. The light-shielding film is a film having an OD (optical density) of 2 or more, which substantially does not 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 of manufacturing a display device, comprising the step of exposing the photomask of the present invention described above with an exposure device to transfer the transfer pattern onto a transfer target to form a hole pattern. .

In the manufacturing method of the display device of the present invention, first, the above-described 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 an exposure light source including 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 material to be transferred. The exposure light source of the exposure device preferably includes i-line, h-line and g-line. It is common and advantageous to apply exposure at the same magnification.

The exposure apparatus used for transferring the transfer pattern using the photomask of the present invention is a system that performs projection exposure at the same magnification, and includes the following. That is, it is an exposure machine used for LCD (liquid crystal display) (or for FPD or liquid crystal). σ) is 0.4 to 0.9) and has a light source (also referred to as a broad wavelength light source) containing at least one of the i-line, h-line and g-line in the exposure light. However, even in an exposure apparatus having a numerical aperture NA of 0.10 to 0.20, the present invention can be applied to obtain the effects of the present invention.

Further, the light source of the exposure apparatus used may be modified illumination (annular illumination, etc.), but the excellent effects of the invention can be obtained even with non-deformed illumination.

The present invention provides a semi-transparent film and a low-light-transmitting film (and, if necessary, a light-shielding film) on a transparent substrate as raw materials for photomasks of the first to third aspects (and the sixth aspect to which these are applied). ) is used. Further, a resist film is formed on the surface to manufacture a photomask.

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

That is, it is preferable that the translucent film of the photomask blank has a transmittance T1 of 30 to 80 (%) for representative wavelengths in the wavelength range from i-line to g-line. Further, the semi-transparent film has a refractive index of 1.5 to 2.9 with respect to the representative wavelength, and has a film thickness with a phase shift amount of approximately 180 degrees. Even if the film thickness of the semi-transparent film having such a refractive index is sufficiently thin, the desired phase shift amount can be obtained, and therefore the wet etching time of the semi-transparent film can be shortened. As a result, side etching of the semitransparent film can be suppressed.

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

The low light-transmitting film can be one that does not substantially transmit the light of the representative wavelength, or one that has a transmittance of less than 30%. Further, the phase shift amount of the low translucent film with respect to representative wavelengths within 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 case of a photomask made of , the angle may be 90 degrees or less, more preferably 60 degrees or less.

Three types of photomasks (Comparative Examples 1-1 and 1-2 and Example 1) shown in FIG. 5 were compared and evaluated in transfer performance by optical simulation. That is, what kind of transfer performance is shown when exposure conditions are set in common for three photomasks having transfer patterns for forming hole patterns with a diameter of 2.0 μm on a transfer target? Optical simulation was performed for

(Comparative Example 1-1)
As shown in FIG. 5, the photomask of Comparative Example 1-1 has a so-called binary mask pattern consisting 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 light-transmitting 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 semitransparent film having an exposure light transmittance (vs. h-line) of 5% and a phase shift amount of 180 degrees. It is also a halftone type phase shift mask having a main pattern consisting of a square light-transmitting portion with one side (diameter) (that is, W1) of 2.0 (μm).

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

The auxiliary pattern is assumed to be the photomask of the first mode, in which a semitransparent film is formed on a transparent substrate. This semitransparent film has an exposure light (for h-line) transmittance T1 of 70 (%) and a phase shift amount of 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.

For both the photomasks of Comparative Examples 1-1 and 1-2 and Example 1, the diameter W2 is 2.0 μm (W1=W2) on the transfer target. 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 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 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 material was set to 1.5 μm.

FIG. 5 shows the performance evaluation of each transfer pattern under the above conditions. FIG. 6 shows an aerial image of the light intensity formed on the transferred material and the cross-sectional shape of the resist pattern formed thereby.

(Optical Evaluation of Photomask)
For example, in order to transfer a fine light-transmitting pattern with a small diameter, the aerial image formed on the transfer target by the exposure light after passing through the photomask, that is, the profile of the transmitted light intensity curve must be good. Specifically, the slope forming the peak of the transmitted light intensity is sharp and rises almost vertically, and the absolute value of the peak light intensity is high (when sub-peaks are formed around is sufficiently high relative to its strength).

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

(1) Depth of focus (DOF)
The depth of focus to be within ±10% or less of the target CD. If the DOF value is high, it is less likely to be affected by the flatness of the object to be transferred (for example, a panel substrate for a display device), a fine pattern can be reliably formed, and its CD (line width) variation can be suppressed.

(2) MEEF (Mask Error Enhancement Factor)
It is a numerical value indicating the ratio of the mask CD error and the CD error of the pattern formed on the transfer medium, and the lower the MEEF, the more the CD error of the pattern formed on the transfer medium can be reduced.

(3) Eop
Eop is a particularly important evaluation item for photomasks for manufacturing display devices. This is the amount of exposure light required to form the desired pattern size on the transferred material. In the manufacture of display devices, the photomask size is large (for example, a square or rectangle with a side of about 300 to 1400 mm on the main surface), so using a photomask with a low Eop value can increase the speed of scanning exposure. , production efficiency is improved.

Based on the above, when evaluating the performance of each sample to be simulated, as shown in FIG. In terms of its superiority, it exhibits stable pattern transferability. This means that the value of MEEF is small and the CD precision of fine patterns is high.

Furthermore, the Eop value of the photomask of Example 1 is very small. This indicates that the photomask of Example 1 has the advantage that the exposure time does not increase or can be shortened even in the manufacture of large-area display devices.

Further, referring to the aerial image of transmitted light intensity shown in FIG. 6, in the case of the photomask of Example 1, the peak of the main pattern portion is increased with respect to the threshold level (Eth) at which the resist is exposed. It can be seen that the inclination of the peak can be made sufficiently high (approximately perpendicular to the surface of the object to be transferred). This point is superior to Comparative Examples 1-1 and 1-2. Here, an increase in Eop and a reduction 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 they are equal to or less than Eth, the transfer of the main pattern is not affected.

A method for reducing the loss of residual resist films resulting from the side peaks will be described below.

The design of the transfer pattern formed on the photomask was changed, and simulations were performed using the samples of Comparative Example 2-1, Comparative Example 2-2, and Example 2 shown in FIG. Both differ 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 set to 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 light-transmitting 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 semitransparent film having an exposure light transmittance (vs. h-line) of 5% and a phase shift amount of 180 degrees. It is also a halftone type phase shift mask having a main pattern consisting of a square light-transmitting portion with a main pattern diameter W1 (one side of the square) of 2.5 (μm).

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

Using the photomasks of Comparative Example 2-1, Comparative Example 2-2 and Example 2, a hole pattern with 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 those for 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, excellent DOF and MEEF as well as performance advantageous to Comparative Examples 2-1 and 2-2 were exhibited. . In the photomask of Example 2, the DOF in particular exceeds 35 μm.

Further, referring to the aerial image of transmitted light intensity and the cross-sectional shape of the resist pattern on the transferred material shown in FIG. 8, the excellent characteristics of the sample of Example 2 are further clarified. 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 resist damage hardly occurs.

From the above results, in the case of pattern transfer using the photomask of the present invention, the mask bias β is about 0.5 (μm), specifically in the range of 0.2 to 1.0 (μm). It has been found that a certain transfer pattern can provide an excellent transfer image that is more practical.

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, the ability to obtain a MEEF value of 2.5 or less in a fine pattern of 2 μm or less will be of great significance in the future manufacture of display devices.

There are no particular restrictions on the use of the photomask of the present invention. The photomask of the present invention can be preferably used in manufacturing display devices including liquid crystal display devices and EL display devices.

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

As an application where such effects can be advantageously obtained, it is advantageous to use the photomask of the present invention for forming isolated hole patterns such as contact holes frequently used in liquid crystal and EL devices. There are two types of patterns: a dense pattern in which a large number of patterns are arranged with a certain regularity and thereby exert an optical influence on each other, and an isolated pattern in which such a regular arrangement pattern does not exist in the surroundings. It is often called by distinguishing it from the pattern. The photomask of the present invention is suitable for forming an isolated pattern on an object to be transferred.

Additional optical films and functional films may be used in 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 light transmittance of the low light-transmitting film from interfering with inspection and photomask position detection, a light-shielding film may be formed in regions other than the transfer pattern. Further, in the semitransparent film, an antireflection layer may be provided on the surface thereof to reduce reflection of drawing light and exposure light.

Claims (14)

A semi-transparent film having a transmittance T1 of 30 to 80 (%) with respect to a representative wavelength of exposure light, and a low light-transmitting film having a transmittance with respect to the representative wavelength lower than that of the semi-transparent film, on a main surface of a transparent substrate. A photomask blank for manufacturing a display device, which is laminated with a film,
The exposure light includes i-line, h-line, and g-line,
The representative wavelength is the h-line,
The semitransparent film is a film that can be wet-etched, has a film thickness of 300 to 2000 Å, has a refractive index of 1.5 to 2.4 with respect to the representative wavelength, and has a phase shift amount. is approximately 180 degrees,
A photomask blank for manufacturing a display device, wherein the low light-transmitting film is wet-etchable, and has an optical density OD of 2 or more with respect to light of the representative wavelength. A semi-transparent film having a transmittance T1 of 30 to 80 (%) with respect to a representative wavelength of exposure light, and a low light-transmitting film having a transmittance with respect to the representative wavelength lower than that of the semi-transparent film, on a main surface of a transparent substrate. A photomask blank for manufacturing a display device, which is laminated with a film,
The exposure light includes i-line, h-line, and g-line,
The representative wavelength is the h-line,
The semitransparent film is a film that can be wet-etched, has a film thickness of 300 to 2000 Å, has a refractive index of 1.5 to 2.4 with respect to the representative wavelength, and has a phase shift amount. is approximately 180 degrees,
The low light-transmitting film can be wet-etched, and in a laminated state of the low light-transmitting film and the semi-transparent film, the transmittance T3 (%) for light of the representative wavelength is T3≦20. and a phase shift amount φ3 of 90 degrees or less. 3. The photomask blank for manufacturing a display device according to claim 1, wherein said low translucent film is made of a material having etching selectivity with respect to the material of said semi-translucent film. 3. The photomask blank for manufacturing a display device according to claim 1, wherein an etching stopper film is provided between said semi-transparent film and said low-translucent film. 5. The photomask blank for manufacturing a display device according to claim 1, wherein said low light-transmitting film is Cr or Cr oxide, nitride, carbide, oxynitride or oxynitride carbide. The semi-transparent film includes a transition metal including Zr, Nb, Hf, Ta, Mo, and Ti, and a material including Si, or an oxide, nitride, oxynitride, carbide, or oxynitride carbide thereof. The photomask blank for manufacturing a display device according to any one of claims 1 to 5, made of the material. A photomask for manufacturing a display device having a transfer pattern by patterning the semi-transparent film and the low light-transmitting film in the photomask blank for manufacturing a display device according to any one of claims 1 to 6. and
The transfer pattern is
a main pattern with a diameter W1 (μm) consisting of a transparent portion where the transparent substrate is exposed;
an auxiliary pattern having a width of d (μm), which is arranged near the main pattern and is composed of a semi-transparent portion in which the semi-transparent film is formed on the transparent substrate;
a low light-transmitting portion disposed in a region of the transfer pattern other than the region where the main pattern and the auxiliary pattern are formed, wherein the semi-light-transmitting film and the low light-transmitting film are laminated on the transparent substrate; , has
A photomask for manufacturing a display device, which satisfies the following formulas (1) and (2).
0.8 ≤ W1 ≤ 4.0 (1)

8. The auxiliary pattern according to claim 7, wherein the shape of the auxiliary pattern is a 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. Photomasks for manufacturing display devices. 9. The photomask for manufacturing a display device according to claim 7, wherein said width d of said auxiliary pattern satisfies d≦W1. The diameter W1 of the main pattern in the transfer pattern is 4.0 (μm) or less, and a hole pattern having a diameter W2 (where W1>W2) is formed on the transferred body corresponding to the main pattern. 10. The photomask for manufacturing a display device according to any one of claims 7 to 9, which is formed. 11. The photomask for manufacturing a display device according to claim 10, wherein said diameter W2 is 3.0 ([mu]m) or less. When the difference W1-W2 between the diameter W1 of the main pattern and the diameter W2 on the transferred material is defined as a bias β (μm),
0.2 ≤ β ≤ 1.0
12. The photomask for manufacturing a display device according to claim 10, wherein: A method for manufacturing a photomask for manufacturing a display device, comprising:
A step of preparing a photomask blank for manufacturing a display device according to any one of claims 1 to 6;
forming the transfer pattern by wet etching the low translucent film and the semi-translucent film, respectively;
The transfer pattern is
a main pattern with a diameter W1 (μm) consisting of a transparent portion where the transparent substrate is exposed;
an auxiliary pattern having a width of d (μm), which is arranged near the main pattern and is composed of a semi-transparent portion in which the semi-transparent film is formed on the transparent substrate;
a low light-transmitting portion disposed in a region of the transfer pattern other than the region where the main pattern and the auxiliary pattern are formed, wherein the semi-light-transmitting film and the low light-transmitting film are laminated on the transparent substrate; , has
A method for manufacturing a photomask for manufacturing a display device, which satisfies the following formulas (1) and (2).
0.8 ≤ W1 ≤ 4.0 (1)

A method for manufacturing a display device,
A step of preparing the photomask for manufacturing a display device according to any one of claims 7 to 12 or the photomask for manufacturing a display device manufactured by the manufacturing method according to claim 13;
exposing the transfer pattern using an exposure device to form a hole pattern on a transferred object;
A method of manufacturing a display device, comprising:

Images