TWI721247B - Photomask for use in manufacturing a display device and method of manufacturing a display device - Google Patents

Abstract

Object: To provide a photomask which is for use in manufacturing a display device and which is capable of stably forming a fine hole pattern on a transfer object. Solution: A photomask for use in manufacturing a display device has a transfer pattern formed on a transparent substrate. The transfer pattern includes a main pattern constituted by a rectangular light-transmitting portion, an auxiliary pattern constituted by a phase shift portion and disposed around the main pattern, and a low transmittance portion formed in a region except the main pattern and the auxiliary pattern. Defining an equilateral octagonal zone having a predetermined width and surrounding the main pattern at a periphery of the main pattern, the auxiliary pattern constitutes at least a part of the equilateral octagonal zone. The transfer pattern includes a plurality of the main patterns one of which is defined as a first main pattern. A second main pattern different from the first main pattern is disposed at a position near to the first main pattern. The equilateral octagonal zone surrounding the first main pattern is constituted by eight sections. The auxiliary pattern having a gap in at least one section faced to the second main pattern is disposed at a periphery of the first main pattern.

Description

Mask for manufacturing display device, and manufacturing method of display device

The present invention relates to a photomask for manufacturing electronic devices, and more particularly to a photomask suitable for manufacturing display devices (flat panel displays: FPD).

Patent Document 1 describes a mask suitable for the exposure environment of a mask for manufacturing a display device, and a mask capable of stably transferring a fine pattern.

In addition, Patent Document 2 describes a method for simultaneously miniaturizing an isolated pattern and a dense pattern for a photomask for forming a fine pattern used in the manufacture of a semiconductor integrated circuit device.

[Prior Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2016-024264

[Patent Document 2] Japanese Patent Laid-Open No. 2006-338057

In display devices including liquid crystal display (liquid crystal display) or organic electroluminescence (EL, Organic Electroluminescence) display devices, it is expected that brighter and more power-saving, high-definition, high-speed display, wide viewing angle and other display performance are desired Promote.

For example, for the Thin Film Transistor (TFT) used in the above-mentioned display device, the contact hole formed in the interlayer insulating film among the plurality of patterns constituting the TFT must have a pattern connecting the upper layer and the lower layer. Only by functioning can the correct action be ensured. On the other hand, in order to increase the aperture ratio of the liquid crystal display device as much as possible, and to make a bright and power-saving display device, the diameter of the contact hole is required to be sufficiently small, and the diameter of the hole pattern is expected to increase. Also miniaturized (for example, less than 3μm). For example, it is considered that a hole pattern having a diameter of 0.8 μm or more and 2.5 μm or less, and furthermore, a diameter of 2.0 μm or less is required. Specifically, it is also desirable to form a pattern having a diameter of 0.8 to 1.8 μm.

However, in the field of semiconductor device (LSI) manufacturing photomasks, which are more integrated than display devices and have made more significant progress in the miniaturization of patterns, there is a need for higher resolution in exposure devices. The optical system with a numerical aperture NA (for example, more than 0.2) promotes the situation of shortening the wavelength of exposure light. As a result, in this field, KrF or ArF excimer lasers (single wavelengths of 248nm and 193nm, respectively) are commonly used.

On the other hand, in the field of lithography for manufacturing display devices, the methods described above are generally not applied in order to improve the resolution. For example, the NA (numerical aperture) of the optical system of the exposure device used in this field is about 0.08~0.12, and it is expected to be in an environment of less than 0.20, for example, about 0.08~0.15 in the future. In addition, exposure light sources also commonly use i-line, h-line, or g-line, and by using a wide-wavelength light source mainly including them, the amount of light used to illuminate a large area is obtained, and there is a strong tendency to pay attention to production efficiency or cost.

In addition, in the manufacture of display devices, as described above, the requirements for miniaturization of patterns have increased. Here, there are several problems in directly applying the semiconductor device manufacturing technology to the manufacturing of the display device. For example, the conversion to a high-resolution exposure device with a high NA (numerical aperture) requires a large investment in equipment, so that it cannot be matched with the price of the display device. Also, for exposure The change of wavelength (using a single wavelength such as the short wavelength of ArF excimer lasers), if applicable to a display device with a large area, is not suitable for not only reducing the production efficiency, but also requiring considerable equipment investment. That is to say, the pursuit of miniaturization of patterns that did not exist before, and on the other hand, the aspect of cost or efficiency that cannot be lost as the existing advantages has become a problem for the masks used in the manufacture of display devices.

The present inventor proposes a photomask having: a main pattern that includes a light-transmitting portion; an auxiliary pattern that is disposed near the main pattern and includes a phase shift portion that shifts the phase of light of a specific wavelength; And a low-transmittance part, which is formed in an area other than the main pattern and the auxiliary pattern (Patent Document 1). This photomask can be advantageously used when stably forming fine isolated holes in a transfer target body such as a display panel substrate.

On the other hand, as the structure of the display device becomes more complicated, the design of the transfer pattern becomes more complicated, and even if the mask described in Patent Document 1 is used, a new problem that cannot be sufficiently eliminated has been discovered by the present inventors. For example, when it is desired to arrange a plurality of hole patterns at a specific close distance to each other on the body to be transferred to form a dense pattern, in the transfer pattern on the mask, the auxiliary patterns of each main pattern are close to each other . In this case, the transmitted light of the auxiliary pattern that is not originally intended for transfer causes the thickness of the resist to be lost on the transferred body, thereby causing the risk of hindering the formation of the intended transfer image. Here, the so-called dense pattern refers to a pattern in which two or more hole patterns are closely arranged on the to-be-transferred body. Therefore, on the mask, the dense pattern refers to a pattern in which two or more main patterns are arranged closely. The so-called closely arranged pattern refers to the pattern on the photomask at the distance to the degree that the hole-forming patterns mutually cause optical influence in the exposure environment. In the specification of this case, in addition to the case where the main patterns are close to each other, there are also the cases where the auxiliary patterns attached to the main pattern are close to each other, which are referred to as adjacently arranged patterns.

Patent Document 2 describes that exposure is carried out by a reduced projection exposure system using ring-shaped illumination. Light, a photomask used in the manufacture of semiconductor integrated circuit devices. Among them, it is described that in a pattern with contour shifters surrounding the opening, when the distance between the contour shifters corresponding to each of the adjacent patterns becomes smaller, by shifting the respective contours The devices are combined with each other to form a phase shifter. Specifically, as shown in FIG. 15, when the opening patterns 721, 722, and 723 are surrounded by four contour shifters 711, 712, and 713, and the interval between the opening pattern 722 and the opening pattern 723 is small, The contour shifter 714 becomes the contour shifter shared by both the opening pattern 722 and the opening pattern 723. In addition, the photomask described in Patent Document 2 is useful for miniaturizing the isolated gap pattern and the isolated line pattern or the dense pattern at the same time.

However, according to research conducted by the inventors, it has been found that the method described in Patent Document 2 is not necessarily useful in a mask for manufacturing a display device.

Therefore, an object of the present invention is to provide a photomask for manufacturing a display device that can stably form a fine hole pattern on a transferred body when manufacturing a display device.

(First aspect)

The first aspect of the present invention is a photomask for manufacturing a display device, which is characterized in that it has a pattern for transfer on a transparent substrate, and the pattern for transfer includes: a main pattern including a quadrangular light-transmitting pattern Auxiliary pattern, which is arranged on the periphery of the main pattern and includes a phase shift part; and a low-transmittance portion, which is formed in an area other than the main pattern and the auxiliary pattern; in defining the periphery of the main pattern In the case of a regular octagonal belt of a specific width surrounded by the main pattern, the auxiliary pattern constitutes at least a part of the regular octagonal belt, and one of the plurality of main patterns included in the transfer pattern is set as the first main Figure At the time of the case, a second main pattern that is different from the first main pattern is arranged at a position close to the first main pattern to form the eight sections of the regular octagonal band surrounding the first main pattern facing the second main pattern. Auxiliary patterns with defects in a section of the pattern side are arranged around the first main pattern.

(2nd aspect)

A second aspect of the present invention is the photomask for manufacturing a display device as in the first aspect, characterized in that when the diameter of the main pattern is W1, the transfer pattern is formed on the body to be transferred The hole pattern of diameter W2 (where W1≧W2) is used as the transfer image of the above-mentioned main pattern.

(3rd aspect)

A third aspect of the present invention is the mask for manufacturing a display device as in the first or second aspect, characterized in that when the arrangement direction of the first main pattern and the second main pattern is set to the X direction , The size of the first main pattern in the X direction is smaller than the size of the Y direction perpendicular to the X direction.

(4th aspect)

A fourth aspect of the present invention is the photomask for manufacturing a display device according to any one of the first to third aspects, wherein the transfer pattern includes three or more of the main patterns in the X direction, The Y direction perpendicular to the X direction, or the dense patterns regularly arranged in the X direction and the Y direction, and each of the main patterns constituting the dense pattern has such that one of the eight segments faces the other main The above-mentioned auxiliary pattern formed by defecting at least one section on the pattern side.

(Fifth aspect)

The fifth aspect of the present invention is used for manufacturing the display device of any one of the above-mentioned first to fourth aspects The photomask is characterized in that the phase shift portion is formed on the transparent substrate with a phase shift of 20 to 80% for the representative wavelength of the exposed light and shifts the phase of the exposed light by approximately 180 degrees. Transfer film.

(6th aspect)

The sixth aspect of the present invention is the photomask for manufacturing a display device according to any one of the above-mentioned first to fifth aspects, characterized in that the optical density OD of the low-transmittance portion with respect to the exposure light is 2 or more The shading part.

(Seventh aspect)

The seventh aspect of the present invention is a method for manufacturing a display device, which includes the following steps: preparing a photomask as in any one of the above-mentioned first to sixth aspects; using a numerical aperture (NA) of 0.08 to 0.15 and having An exposure device including at least any one of the i-line, h-line, and g-line exposure light source exposes the transfer pattern to form a hole pattern with a diameter W2 of 0.8 to 3.0 (μm) on the transferred body.

According to the present invention, in the case of manufacturing a display device, a fine hole pattern can be stably formed on the transferred body.

1: Main pattern

1a: Main pattern

1b: Main pattern

2: auxiliary pattern

2a: auxiliary pattern

2b: auxiliary pattern

3: Low light transmission part

4: Transmitting part

5: Phase shift part

10: Transparent substrate

11: Phase shift film

12: Low light transmission film

12p: Low light transmission film pattern

13: The first photoresist film

13p: The first resist pattern

14: 2nd photoresist film

14p: 2nd resist pattern

20: resist pattern

21a: Hole pattern

21b: Hole pattern

22: recess

30: Mask base

711: Contour shifter

712: Contour Shifter

713: Contour Shifter

714: contour shifter

721: opening pattern

722: Opening Pattern

723: opening pattern

d: Width of auxiliary pattern 2

L: slit pitch

P: hole spacing

S: area

W1: width of pattern 1

X: direction

Y: direction

Fig. 1 is a diagram showing the main part of the transfer pattern of the photomask described in Patent Document 1, (a) is a plan view, and (b) is a cross-sectional view at the position A-A of (a).

Figures 2(a)~(c) are top views showing the patterns of the masks of Reference Examples 1~3.

Fig. 3 is a graph showing the simulation results of Reference Examples 1 to 3.

Fig. 4 is a plan view showing a state where the main patterns of Reference Example 3 are arranged close to each other.

Fig. 5 (a) is a plan view illustrating a state where the first main pattern and the second main pattern are sufficiently separated, and (b) is a cross-sectional view illustrating the structure of the resist pattern formed on the transfer body in this case.

Fig. 6(a) is a plan view illustrating a situation where the second main pattern approaches the first main pattern, and (b) is a cross-sectional view illustrating the structure of the resist pattern formed on the transfer body in this situation.

Fig. 7 illustrates the main part of the transfer pattern provided in the mask for manufacturing the display device of the embodiment of the present invention, (a) is a plan view, and (b) is a cross-sectional view at the position of BB in (a) Figure.

Fig. 8 is a plan view showing an example of dividing the auxiliary pattern arranged around the main pattern into eight segments.

FIG. 9 is a cross-sectional view illustrating the structure of the resist pattern formed on the transferred body when the transfer pattern of the photomask according to the embodiment of the present invention is applied.

Fig. 10(a)~(e) are top views showing the pattern of the photomask of Reference Examples 4~8.

Figures 11(f)~(i) are top views showing the patterns of the photomasks of Examples 1~4.

Fig. 12 is a diagram showing the simulation results of the reference example and the example in the embodiment of the present invention.

FIG. 13 is a plan view showing an example of a transfer pattern including a mask provided with a main pattern of a mask deviation β2.

Fig. 14(a)~(f) are process diagrams illustrating an example of a manufacturing method of a photomask applicable to the embodiment of the present invention.

FIG. 15 is a plan view showing the pattern of the mask described in Patent Document 2. FIG.

[Design of mask for forming hole pattern with auxiliary pattern]

Fig. 1 shows the main part of the transfer pattern of the photomask described in Patent Document 1, (a) It is a top view schematic diagram, and (b) is a cross-sectional schematic diagram at the A-A position of (a).

The transfer pattern of the photomask shown in the figure has a main pattern 1 including a light-transmitting part, and an auxiliary pattern 2 arranged around the main pattern 1 to surround the main pattern 1. The auxiliary pattern 2 is attached to the main pattern 1 and arranged around the main pattern 1.

In addition, a phase shift film 11 and a low light transmission film 12 are formed on the transparent substrate 10. The main pattern 1 includes the light-transmitting portion 4 exposing the transparent substrate 10, and the auxiliary pattern 2 includes the phase shifting portion 5 exposing the phase shift film 11 on the transparent substrate 10. In addition, the low light transmission portion 3 surrounds the main pattern 1 and the auxiliary pattern 2 respectively.

The low light transmission part 3 includes a laminated film of a phase shift film 11 and a low light transmission film 12 formed on the transparent substrate 10. The low light transmission part 3 may also include a single-layer film of the low light transmission film 12 formed on the transparent substrate 10. That is, the low light transmission part 3 includes at least a portion where the low light transmission film 12 is formed. In the transfer pattern shown in the figure, the area other than the area where the main pattern 1 and the auxiliary pattern 2 are formed becomes the low light-transmitting portion 3.

The phase shift film 11 has a phase shift amount that shifts the exposure light of the representative wavelength in the wavelength range of the i-line to the g-line by approximately 180 degrees. That is, the auxiliary pattern 2 has a function of reversing the phase of the transmitted light by the phase shift film 11. In addition, the phase shift film 11 has a transmittance of T1 (%) for the exposure light of the above-mentioned representative wavelength.

According to Patent Document 1, after an optical simulation of forming a hole pattern on the transferred body using a photomask with the above-mentioned transfer pattern, compared with a phase shift mask without a binary mask or auxiliary pattern, it is obvious It has excellent performance in Eop (the amount of exposure light required to form a pattern of the target size on the transferred body) or DOF (Depth of Focus).

In order to form a finer pattern on the body to be transferred, the inventor performed an optical simulation on the photomask shown in Figs. 2(a) to (c). Here, the photomask in Figure 2(a) is referred to as Reference Example 1, and Figure 2(b) The photomask shown is referred to as Reference Example 2, and the photomask shown in FIG. 2(c) is referred to as Reference Example 3. Then, using each of the masks of Reference Examples 1 to 3 with a main pattern including a hole pattern with a diameter W1 of 2.0 μm, a positive type photoresist was formed on the transferred body (display panel substrate, etc.) corresponding to the diameter W2 (Here 1.5μm) the simulation of the transfer image of the hole pattern.

Furthermore, as described above, the diameter W1 on the mask is set to be W1≧W2 (preferably W1>W2) relative to the target diameter W2 on the object to be transferred. Here, if the mask deviation β1 (μm) is set to β1=W1-W2, then β1 is set to 0.5 (μm) here.

The simulation conditions are as follows.

(Reference example 1)

In Reference Example 1, as shown in Figure 2(a), using a mask containing a binary mask, the light-transmitting portion of a square with a diameter W1=2μm surrounded by a low-transmitting portion (light-shielding portion) 3 is used. Set the hole pattern as main pattern 1.

(Reference example 2)

In Reference Example 2, as shown in Figure 2(b), using a halftone type phase shift mask, the transmittance of the exposed light is 5.2% and the phase shift is 180 degrees. A hole pattern including a square light-transmitting portion with a diameter W1=2 μm surrounded by the offset portion 5 is set as the main pattern 1.

(Reference example 3)

In Reference Example 3, as shown in Figure 2(c), a photomask including a phase shift mask with auxiliary patterns is used, and a hole pattern including a square light-transmitting portion with a diameter of W1=2μm is set as the main The pattern 1 and the auxiliary pattern 2 of the regular octagonal band surround the periphery of the pattern 1. In addition, the auxiliary pattern 2 includes a phase shift portion with a light transmittance of 45% and a phase shift of 180 degrees. The area outside the main pattern 1 and the auxiliary pattern 2 includes a low light transmittance with an optical density of OD≧2. Section (shading section) 3. The distance (L) between the center of the main pattern 1 and the center of the auxiliary pattern 2 in the width direction (L) is set as 3.25μm, the width (d) of the auxiliary pattern 2 is set to 1.3μm. The photomask of Reference Example 3 was designed based on the structure described in Patent Document 1.

Using the respective photomasks corresponding to the above reference examples 1 to 3, a hole pattern with a width W2=1.5 μm was formed on the transferred body.

The simulated exposure conditions are as follows.

The optical system coefficient value of the exposure device has an aperture NA of 0.1 and a coherence factor σ of 0.5. In addition, a light source including all i-line, h-line, and g-line (broad-wavelength light source) is used in the exposure light source, and the intensity ratio is set to g:h:i=1:1:1.

The optical evaluation items of the mask are as follows.

(1) Depth of focus (DOF)

The depth of focus (DOF) is used on the transferred body to make the CD change relative to the target CD into a specific range (for example, ±10%) when the defocus occurs during exposure, and it is ideal Its value is larger. If the DOF value is high, it is less likely to be affected by the flatness of the transferred body (for example, a panel substrate for a display device), so that a fine pattern can be formed reliably and the CD unevenness can be suppressed. In the simulation of this case, as the DOF value, the target CD±10% is set as the benchmark. Here, the so-called CD is an abbreviation of Critical Dimension, and is used in the meaning of pattern width. The photomask for display device manufacturing is larger than the photomask for semiconductor device manufacturing. In addition, the transfer target (display panel substrate, etc.) is also large in size, and it is difficult to obtain complete flatness. Therefore, the DOF value is increased. The mask is of greater significance.

(2) Mask Error Enhancement Factor (MEEF: Mask Error Enhancement Factor)

The mask error enhancement factor is a numerical value representing the ratio of the CD error of the pattern formed on the transferred body to the CD error on the mask. The lower the MEEF, the more the pattern formed on the transferred body can be reduced. CD error. The specifications of display devices have evolved, requiring miniaturization of patterns, and A photomask with a pattern close to the resolution limit of the exposure device is required. Therefore, in the photomask for manufacturing display devices, there is a higher possibility that MEEF will be emphasized in the future.

(3)Eop

Eop (hereinafter also referred to as "Eop dose") is a particularly important evaluation item in the mask for display device manufacturing. Eop is the amount of exposure light required to form the required pattern size on the body to be transferred. The size of the photomask used in the manufacture of the display device is extremely large (for example, a square or rectangle with one side of the main surface of about 300-2000 mm). Therefore, if a mask with a lower Eop value is used, the scanning exposure speed can be increased, and the production efficiency can be improved.

The specific evaluation results of the above evaluation items are shown in FIG. 3.

First of all, if we focus on Eop, compared with the photomasks of Reference Example 1 and Reference Example 2, the exposure amount (Eop value) used to obtain the hole pattern of the target size is smaller than 30% for the mask of Reference Example 3. Therefore, it can be seen that if the mask of Reference Example 3 is used, higher production efficiency can be obtained. In addition, compared with the photomasks of Reference Example 1 and Reference Example 2, the DOF value of the photomask of Reference Example 3 becomes higher, and the MEEF value of the photomask becomes lower. Therefore, it can be seen that the photomask of Reference Example 3 is also extremely advantageous in DOF or MEEF.

[Design of hole patterns in close proximity to each other]

On the other hand, if the resolution required for the display device increases, the number of pixels per unit area increases, resulting in an increase in integration. Therefore, it is necessary to arrange a plurality of main patterns (hole patterns) close to each other as a pattern for transfer of a mask for manufacturing a display device. Hereinafter, a case where the photomask of Reference Example 3 described above is applied to the formation of dense patterns including a plurality of main patterns will be studied.

FIG. 4 shows a situation in which the patterns (combining the main pattern and the auxiliary pattern formed on the periphery thereof, which are also referred to as the hole forming pattern in the specification of this case) applied to the reference example 3 mentioned above are arranged close to each other. Here, one of the two main patterns is set as the first main pattern 1a, and the other is set as the second main pattern 1b. Next, consider that the position of the second main pattern 1b is from the arrow side to the first main pattern 1a. When approaching, the hole pitch P, which is the distance between the centers of gravity of the two main patterns 1a, 1b, and the cross-sectional shape of the resist pattern formed on the body to be transferred.

First, as shown in Fig. 5(a), when the first main pattern 1a and the second main pattern 1b are sufficiently separated (P=12μm), as shown in Fig. 5(b), on the body to be transferred The resist pattern (here, a pattern containing a positive photoresist) 20 forms hole patterns 21a, 21b corresponding to the respective main patterns 1a, 1b.

On the other hand, as shown in Fig. 6(a), when the second main pattern 1b is close to the first main pattern 1a (P=8μm), the auxiliary pattern 2a is arranged around each main pattern 1a, 1b , 2b becomes extremely close to each other. At this time, if the cross-section of the resist pattern 20 formed on the body to be transferred is observed, as shown in FIG. 6(b), in addition to the hole patterns 21a, 21b corresponding to the main patterns 1a, 1b, among others A recess 22 is formed in the middle portion, and therefore, a large loss of the resist film thickness occurs. This partial reduction of the resist residual film may adversely affect the processing stability of the display device substrate using the resist pattern as an etching mask.

Therefore, the inventors of the present invention have favorable characteristics in terms of Eop or DOF, but the above-mentioned partial reduction of the resist residual film and other disadvantages such as the hole formation pattern of Reference Example 3 have been studied, and they have investigated the ability to eliminate the disadvantages. The best condition of the mask.

<The composition of the mask>

Next, the structure of the mask for manufacturing a display device according to the embodiment of the present invention will be described.

The photomask for manufacturing the display device of the embodiment of the present invention has a pattern for transfer on a transparent substrate, and the pattern for transfer includes: a main pattern including a quadrangular light-transmitting part; and an auxiliary pattern, which is arranged on the above The periphery of the main pattern and includes the phase shift part; and A low light transmission portion, which is formed in an area other than the main pattern and the auxiliary pattern; when defining a regular octagonal band of a specific width surrounding the main pattern in the periphery of the main pattern, the auxiliary pattern constitutes the regular octagonal band When at least a part of the plurality of main patterns included in the transfer pattern is set as the first main pattern, a second main pattern different from the first main pattern is arranged close to the first main pattern In the position, among the eight sections of the regular octagonal belt surrounding the first main pattern, the auxiliary patterns with defects in one of the sections facing the second main pattern side are arranged on the periphery of the first main pattern.

Hereinafter, a specific description will be given using FIG. 7.

Fig. 7 shows the main part of the transfer pattern included in the mask for manufacturing the display device according to the embodiment of the present invention, (a) is a plan view, and (b) is a cross-sectional view at the position of BB in (a) Figure.

The above-mentioned photomask for display device manufacturing (hereinafter also referred to as "mask"), for example, includes a transfer film formed by patterning a phase shift film 11 and a low-transmittance film 12 formed on a transparent substrate 10, respectively. pattern. The transfer pattern includes a main pattern 1 (1a, 1b) and an auxiliary pattern 2 (2a, 2b) arranged around the main pattern 1. When the auxiliary pattern 2 defines a regular octagonal band of a specific width surrounding the main pattern 1, it has a shape that constitutes at least a part of the regular octagonal band.

Two main patterns 1 are arranged in the X direction, one of which becomes the first main pattern 1a, and the other becomes the second main pattern 1b. An auxiliary pattern 2a is arranged around the first main pattern 1a, and an auxiliary pattern 2b is arranged around the second main pattern 1b. Furthermore, in FIG. 7(a), the main pattern on the left side is set as the first main pattern, and the main pattern on the right side is set as the second main pattern, but either one can be set as the first main pattern.

In this embodiment, the main pattern 1 includes the light-transmitting portion 4 exposing the transparent substrate 10, and the auxiliary pattern 2 includes the phase shifting portion 5 exposing the phase shift film 11 on the transparent substrate 10. In addition, the area other than the main pattern 1 and the auxiliary pattern 2 becomes the low light transmission part 3 in which at least the low light transmission film 12 is formed on the transparent substrate 10.

In this embodiment, the low light transmission part 3 is formed by laminating a phase shift film 11 and a low light transmission film 12 on a transparent substrate 10. The phase shift film 11 has a phase shift amount that shifts the exposure light of the representative wavelength in the wavelength range of the i-line to the g-line by approximately 180 degrees. In addition, the transmittance of the phase shift film 11 to the exposure light of the above-mentioned representative wavelength is T1 (%).

The low-transmittance film 12 can be set to have a specific low transmittance for the representative wavelength of the exposed light. In this embodiment, the low-transmittance film 12 can have a lower transmittance T2 than the transmittance T1 (%) of the phase shift film 11 for the exposure light of the representative wavelength in the wavelength range of the i-line ~ g-line. %). Alternatively, the low light-transmitting film 12 can also be a light-shielding film that does not substantially transmit exposure light.

Here, when a fine pattern (hole pattern) corresponding to the main pattern 1 of the photomask is formed on the transferred body by exposure using the photomask, if the diameter W1 of the main pattern 1 is set to 4μm Below, a fine pattern with a diameter of W2 (μm) (W1≧W2, more preferably W1>W2) can be formed on the transferred body.

Specifically, the diameter W1 (μm) of the main pattern 1 is preferably 0.8≦W1≦4.0, and more preferably 1.0≦W1≦3.5. Furthermore, it can be set to 1.2<W1≦3.0, and when it is necessary to make it finer, it can be set to 1.2<W1<2.5.

In addition, the diameter W2 (μm) of the hole pattern formed on the transferred body as the transfer image of the main pattern 1 is preferably 0.8≦W2≦3.0, more preferably 0.8≦W2≦2.5, and still more preferably 0.8 ≦W2≦2.0 or 0.8≦W2≦1.8. Or, it can be set to 0.8<W2<2.0 or 0.8<W2<1.8. When it is necessary to be more refined, it can be set to 0.8<W2<1.5.

In addition, the photomask of this embodiment can be used for the purpose of forming a fine-sized pattern useful for the manufacture of a display device. For example, when the diameter W1 of the main pattern 1 is 3.0 (μm) or less, a more significant effect can be obtained.

However, in a photomask that requires a hole pattern to be formed on the body to be transferred (for example, Reference Examples 1 to 3), it is advantageous to provide the mask deviation β1 as described above. That is, if the diameter of the hole pattern on the photomask is set to W1 and the diameter of the hole pattern formed on the to-be-transferred body is set to W2, then W1=W2 can also be set, but it is preferably W1>W2. For example, if β1 (μm) is set as the deviation value (W1-W2), and β1>0 (μm), the deviation value β1 (μm) is preferably 0.2≦β1≦1.0, more preferably 0.2≦β1≦0.8 . In this way, by specifying the relationship between the diameter W1 and the diameter W2 as the deviation value β1, advantageous effects such as reduction in the loss of the film thickness of the resist pattern on the transferred body can be obtained.

Furthermore, the main pattern 1 includes a quadrilateral pattern, and the diameter W1 of the main pattern 1 is the size of one side of the quadrilateral. For example, if the main pattern 1 is a square pattern, the diameter W1 of the main pattern 1 refers to the size of one side of the square, and if the main pattern 1 is a rectangular pattern, the diameter W1 refers to the size of the long side. In addition, the shape of the main pattern 1 refers to the shape of the main pattern 1 when viewed from above. Furthermore, the diameter W2 of the hole pattern formed on the body to be transferred refers to the length of the part with the largest distance between the two opposing sides.

The mask deviation β1 as described above can also be given to the mask of this embodiment. In this embodiment, since the two hole forming patterns are formed close to a specific distance, the size given as the mask deviation β1 may be larger than the isolated pattern (reference examples 1 to 3, etc.).

Furthermore, it is preferable to generate the mask of this embodiment in a situation where a mask deviation of an unequal size is provided with respect to the X direction and the Y direction perpendicular to the X direction and the Y direction perpendicular to the X direction according to the positional relationship of the two hole forming patterns arranged close to each other. Therefore, this mask deviation is set to β2, and the amount of deviation given to the X direction and the Y direction perpendicular thereto is set to β2(x) and β2(y), respectively. The details of the mask deviation β2 are described below.

Regarding the representative wavelength of the exposure light used for the exposure of the photomask of the present embodiment having the above-mentioned transfer pattern, the phase difference Φ between the main pattern 1 and the auxiliary pattern 2 is approximately 180 degrees. That is, the phase difference Φ1 between the light of the representative wavelength passing through the main pattern 1 and the light of the representative wavelength passing through the auxiliary pattern 2 becomes approximately 180 degrees. The so-called approximately 180 degrees means 120 to 240 degrees. The above-mentioned phase difference Φ1 is preferably 150 to 210 degrees.

Furthermore, the photomask of this embodiment is more effective when using at least one type of exposure light including i-line, h-line, and g-line. In particular, it is preferably suitable for use including i-line, h-line, and g-line. The wide-wavelength light is used as exposure light. In this case, any wavelength in the wavelength range of i-line ~ g-line can be set as the representative wavelength. For example, the photomask of this embodiment can be constructed using the h line as the representative wavelength. More preferably, the phase difference Φ1 with respect to the above-mentioned representative wavelength is Φ1=180 degrees.

In the photomask of this embodiment, in order to realize the above-mentioned phase difference, it is only necessary to set the main pattern 1 as the light-transmitting portion 4 where the main surface of the transparent substrate 10 is exposed, and set the auxiliary pattern 2 as the light-transmitting portion 4 formed on the transparent substrate 10. In the phase shift portion 5 where the phase shift film 11 is exposed, the phase shift amount of the phase shift film 11 with respect to the above-mentioned representative wavelength may be approximately 180 degrees.

The transmittance T1 of the phase shift part 5 can be set as follows. That is, if the transmittance of the phase shift film 11 formed in the phase shift portion 5 to the above-mentioned representative wavelength is set to T1 (%), it is preferably 20≦T1≦80, and more preferably 30≦T1≦75. More preferably, it is 40≦T1≦75. If the transmittance of the auxiliary pattern 2 is high, the width (d) of the auxiliary pattern can be reduced in order to obtain a specific amount of transmitted light. Therefore, it has the advantage of obtaining a degree of freedom of configuration that can avoid mutual physical interference in dense patterns. . On the other hand, if the transmittance T1 is slightly reduced and the width (d) of the auxiliary pattern is enlarged, there is an advantage that the manufacturing difficulty of pattern formation is alleviated. In this case, the transmittance T1 is preferably 40-60 (%). Furthermore, the transmittance T1 (%) here is the transmittance of the above-mentioned representative wavelength based on the transmittance of the transparent substrate 10 (100%).

In the photomask of this embodiment, the low light transmission part 3 is formed in a region other than the region where the main pattern 1 and the auxiliary pattern 2 are formed. Here, the main pattern 1 and the auxiliary pattern 2 are separated by a low light transmission part 3. The low light transmission portion 3 can be configured as follows.

The low light transmission part 3 is a low light transmission film (i.e., light-shielding film) 12 that is substantially impermeable to the exposed light (the light of the representative wavelength in the wavelength range of the i-line ~ g-line), and can be set on the transparent substrate 10 It is formed by forming a film with an optical density OD≧2 (preferably OD≧3).

In addition, the low light transmission portion 3 may be formed by forming a low light transmission film 12 that allows exposure light to pass through with a transmittance in a specific range. However, when the exposure light is transmitted through a specific range of transmittance, the transmittance T3 (%) of the low light transmission portion 3 to the above-mentioned representative wavelength is set to be compared with the transmittance T1 (%) of the above-mentioned phase shift portion 5 , Those satisfying 0<T3<T1, preferably satisfying 0<T3≦20. Here, when the phase shift portion 5 is not a single-layer film including the phase shift film 11 but includes a laminated film of the phase shift film 11 and the low-transmittance film 12, the transmittance of the laminated film is set to T3(%). The transmittance T3 (%) here is also the transmittance of the representative wavelength based on the transmittance of the transparent substrate 10 in the same manner as described above.

In addition, when the low light transmission film 12 transmits the exposure light with a specific range of transmittance, the phase shift amount Φ3 of the phase shift film 11 and the low light transmission film 12 in the layered state is preferably 90 (Degree) or less, more preferably 60 (degree) or less. The so-called "90 degrees or less" means that if expressed in radians, the above-mentioned phase difference is "(2n-1/2)π~(2n+1/2)π (where n is an integer)". Regarding the phase difference, in the same manner as described above, it is assumed to be the representative wavelength included in the exposure light.

In addition, as the sole property of the low light transmission film 12 used in the mask of this embodiment, it is preferable to substantially not transmit light of the above-mentioned representative wavelength (OD≧2, more preferably OD>3), or It has a transmittance (T2 (%)) less than 30 (%) (ie 0<T2<30) and the phase shift (Φ2) is approximately 180 degrees. The so-called approximately 180 degrees refers to those of 120 to 240 degrees. Preferably, the phase offset Φ2 is 150~210 degree.

The transmittance T2 (%) here is also the transmittance of the above-mentioned representative wavelength based on the transmittance of the transparent substrate 10 in the same manner as described above.

In the transfer pattern of this embodiment, if the width of the auxiliary pattern 2 is d (μm), a significant effect can be obtained when the relationship of the following formula (1) is established.

At this time, if the distance between the center of the main pattern 1 and the center of the auxiliary pattern 2 in the width direction is defined as the slit pitch L (μm), it is preferably 1.0<L≦5.0, and more preferably 1.5<L≦4.5. However, the auxiliary pattern 2 constitutes at least a part of the area of the regular octagonal band of the main pattern 1 that is surrounded by the low light transmission portion 3. Therefore, the main pattern 1 and the auxiliary pattern 2 are not in contact with each other, that is, on the condition that the low light transmission part 3 is interposed between the main pattern 1 and the auxiliary pattern 2 to determine the slit pitch L and the main pattern Diameter W1.

The width d (μm) of the auxiliary pattern 2 is set to be suitable for the exposure conditions (exposure device used) of the mask of this embodiment, and the auxiliary pattern with the transmittance T1 is not resolved. To cite a specific example, the width d (μm) of the auxiliary pattern 2 is preferably d≧0.7, more preferably d≧0.8. In addition, when compared with the width W1 (μm) of the main pattern 1, d≦W1 is more preferable, and d<W1 is more preferable.

Regarding the width d (μm) of the auxiliary pattern 2, the relational expression represented in the above formula (1) is more preferably the following formula (1)-1, and still more preferably the following formula (1)-2.

The shape of the main pattern 1 provided in the transfer pattern of this embodiment is a quadrilateral. Specifically, the shape of the main pattern 1 is preferably, for example, a square or a rectangle. When the shape of the main pattern 1 is a quadrilateral, the position of the center of gravity of the quadrilateral and the center of the width direction of the auxiliary pattern 2 The distance becomes the slit pitch L.

In this embodiment, when defining a regular octagonal band of a specific width surrounding the main pattern 1 around the periphery of the main pattern 1, the auxiliary pattern 2 becomes a pattern that constitutes at least a part of the regular octagonal band. The so-called regular octagonal belt refers to a shape whose outer and inner circumferences are both octagonal and approximately a fixed width. As shown in Fig. 7, the auxiliary pattern 2 has a fixed width except for the corners. The regular octagonal bands defining the auxiliary pattern 2 are arranged around the main pattern 1 in such a way as to surround the main pattern 1. In addition, the center of gravity of the regular octagon that becomes the inner and outer contours of the regular octagon band of the auxiliary pattern 2 is located at the same position as the center of gravity of the main pattern 1. In this embodiment, for convenience of description, as shown in FIG. 8, the regular octagonal belt is divided into 8 segments corresponding to each side of the octagon on the outer circumference (or inner circumference). Here, the section on the right end of Fig. 8 among the eight divided sections is referred to as section A, the upper section adjacent to it is referred to as section H, and the lower section is referred to as section B. That is, from the section A, the sections B, C, D, E, F, G, and H are set clockwise.

As shown in FIG. 4, when the second main pattern 1b is placed close to the first main pattern 1a, in this embodiment, the regular octagonal belt is arranged around the first main pattern 1a. Among the 8 sections A to H, the auxiliary pattern 2a has a defective shape in a section facing the side of the second main pattern 1b. Specifically, as shown in FIG. 7(a), an auxiliary pattern 2a in which a part of the octagonal band is missing is arranged on the periphery of the first auxiliary pattern 1a. As shown in the figure, the auxiliary pattern 2a attached to the first main pattern 1a has a shape with a defect on the side facing the second main pattern 1b, that is, at the right end section (corresponding to the above section A). In addition, the auxiliary pattern 2b attached to the second main pattern 1b also has a shape that has a defect in a section (corresponding to the above-mentioned section E) on the side facing the first main pattern 1a. That is, the two main patterns have auxiliary patterns in the shape of octagonal bands with defects in a section located on opposite sides.

That is, when the two hole-forming patterns are arranged at a close distance less than a certain distance, The auxiliary patterns of each main pattern are missing between the two main patterns. Therefore, if the centers of gravity of the two main patterns are connected by a straight line (not shown), the straight line does not pass through the auxiliary pattern at all.

Furthermore, it is preferable that the auxiliary pattern is not substantially arranged in the region S (shown by the dotted line in FIG. 7(a)) sandwiched by the mutually opposed sides of the two main patterns. However, when a part of the auxiliary pattern enters the area S, it is preferable that the part does not have a side parallel to the mutually opposed sides of the two main patterns. In the aspect shown in FIG. 7, the end of the auxiliary pattern enters the area S, but the end only has a side that is inclined to the mutually opposed sides of the two main patterns.

Furthermore, it is preferable that there is no island-shaped auxiliary pattern (a shape surrounded by a closed straight line or a curved line) in the region S.

Furthermore, it is preferable that 90% or more of the area in the above-mentioned region S includes a low light transmission portion. Thereby, the shape of the resist pattern of the two hole patterns formed on the transferred body becomes good, and the loss of the resist residual film thickness can be suppressed.

If the auxiliary patterns 2a, 2b with partial segment defects are arranged in this way, the loss of the resist film thickness due to the recess 22 shown in FIG. 6(b) is eliminated as shown in FIG. 9, and it has a good profile. The shape of the resist pattern. Furthermore, Fig. 6(b) and Fig. 9 both show the case where the hole pitch P is 8 μm.

The allowable range of the loss of the resist film thickness observed in FIG. 6(b) can be determined according to the manufacturing conditions of the display device to be obtained by using the photomask. If the initial film thickness (coating film thickness) of the resist film is set to 100%, the allowable range of its loss is 10% or less of the initial film thickness, more preferably 5% or less, which is a good condition.

Therefore, in this embodiment, whether or not to partially defect the auxiliary patterns 2a, 2b attached to the main patterns 1a, 1b that are close to each other, it is only necessary to grasp the amount of loss of resist film thickness by experiment or simulation in advance, and base it on it. The result can be judged. Specifically, the judgment is made in the following way To be useful, that is, when the loss of the resist film thickness exceeds 10%, for example, part of the auxiliary patterns 2a and 2b is damaged, and when it becomes 10% or less, the auxiliary patterns 2a and 2b are not damaged.

Furthermore, when the second main pattern 1b is arranged at a position close to the first main pattern 1a, it is preferable that the distance D (refer to FIG. 4) between the auxiliary patterns 2a and 2b becomes 1.0 μm or less, The section (section A mentioned above) facing the side of the second main pattern 1b of the auxiliary pattern 2a arranged on the periphery of the first main pattern 1a is defective. Similarly, it is preferable that the second main pattern 1b also forms an auxiliary pattern 2b that makes the section facing the side of the first main pattern 1a (section E mentioned above) missing. Furthermore, it is more preferable that the defect in the above-mentioned segment is applied when the distance D between the auxiliary patterns 2a and 2b is 1.5 μm or less.

The above situation is exemplified in view of the resolution performance of the exposure device for the display device.

Furthermore, the so-called distance between the auxiliary patterns as shown in FIG. 4 refers to the distance between the opposing sections (the length of the vertical line). Therefore, when the two main patterns 1a, 1b are arranged adjacent to each other in a certain direction as shown in the figure, and the respective main patterns 1a, 1b are respectively surrounded by the corresponding (attached) auxiliary patterns 2a, 2b, in In the arrangement direction of the two main patterns 1a and 1b, the distance between the opposite (facing to each other) sides of the auxiliary patterns 2a and 2b becomes the distance D between the auxiliary patterns.

In addition, in the photomask of this embodiment, when the hole pitch P, which is the distance between the centers of gravity of the main patterns 1a and 1b, is 1.6 μm or more, preferably 3 μm or more, the remarkable effect of the present invention can be obtained. If the value of the hole pitch P is too small, there is a risk of inadequate situations where the residual film amount of the resist pattern formed at the position corresponding to the two main patterns cannot be obtained sufficiently, or the following mask The value of the deviation β2 becomes too large and pattern design becomes difficult.

The optical simulations of the embodiments and reference examples of the present invention will be described below.

Fig. 10 is a plan view of the main part of the transfer pattern included in the photomask of the reference example In the formula diagram, (a) represents Reference Example 4, (b) represents Reference Example 5, (c) represents Reference Example 6, (d) represents Reference Example 7, and (e) represents Reference Example 8. 11 is a schematic plan view showing the main part of the transfer pattern provided in the photomask of the embodiment of the present invention, (f) shows Example 1, (g) shows Example 2, (h) shows Example 3 , (I) represents Example 4.

10(a) shows the case where the hole pitch P of the main patterns 1a, 1b (refer to FIGS. 5 to 7) is 16 μm and the auxiliary patterns 2a, 2b of the regular octagonal belt have no segmental defects. FIG. 10(b) ) Means that the hole pitch P of the main patterns 1a, 1b is 12 μm and the auxiliary patterns 2a, 2b have no segment defects. 10(c) shows the case where the hole pitch P of the main patterns 1a, 1b is 9 μm and the auxiliary patterns 2a, 2b have no segment defects, and Fig. 10(d) shows that the hole pitch P of the main patterns 1a, 1b is 8.75 μm and the auxiliary patterns 2a, 2b have no segment defects. Fig. 10(e) shows a situation in which the hole pitch P of the two main patterns 1a, 1b is 8.75 μm, and a section of each auxiliary pattern 2a, 2b is combined and shared.

On the other hand, Fig. 11(f) shows the case where the hole pitch P of the main patterns 1a, 1b is 8.75μm and the auxiliary patterns 2a, 2b are missing a section, and Fig. 11(g) shows the hole pitch of the main patterns 1a, 1b When P is 8 μm and the auxiliary patterns 2a and 2b are missing a section. 11(h) shows the case where the hole pitch P of the main patterns 1a, 1b is 7.5 μm and the auxiliary patterns 2a, 2b are missing a section, and Fig. 11(i) shows that the hole pitch P of the main patterns 1a, 1b is 7μm and 3 segments of auxiliary patterns 2a and 2b are missing.

In addition, in this simulation, the case of using the mask (binary mask) shown in Figure 2(a) above is set as Reference Example 1, and the mask (halftone mask) shown in Figure 2(b) above will be used. The case of formula phase shift mask) is set as Reference Example 2. The main patterns applicable to Reference Example 1 and Reference Example 2 are isolated patterns without auxiliary patterns.

The optical simulation of the patterns of the above-mentioned masks was carried out, and the results as shown in Fig. 12 were obtained. ^{In this simulation, in addition to Reference Example 1 and Reference Example 2, a dose of 80mJ/cm 2} (Eop dose) was used as the exposure energy for the transfer of the main pattern (isolated pattern) shown in Figure 2(c). ) Is used as a reference to evaluate the resist pattern formed on the body to be transferred when the dose is applied. Furthermore, "panel X-CD" and "panel Y-CD" correspond to the size of the hole pattern formed on the transferred body in the X direction and the Y direction corresponding to the main pattern of the mask. Furthermore, in each reference example and each embodiment, the target size of X-CD and Y-CD is set to 1.5 μm.

First, in Reference Example 4 of Fig. 10(a), the two main patterns 1a, 1b are sufficiently separated, and therefore, each of the main patterns 1a, 1b substantially exhibits the optical performance as an isolated pattern. This aspect is also the same in Reference Example 5 of FIG. 10(b) or Reference Example 6 of FIG. 10(c). On the other hand, if the two main patterns 1a and 1b are close to each other and the hole pitch P is reduced to 8.75 μm as in Reference Example 7 of FIG. 10(d), the distance D between the auxiliary patterns 2a and 2b becomes 0.95 μm. At this time, the loss of resist film thickness exceeds 12%.

Here, as in Reference Example 8 of Fig. 10(e), when the auxiliary patterns 2a, 2b of the main patterns 1a, 1b that are close to each other are partially joined to one another (1 segment) to share them, The loss of resist film thickness is also close to 12%, almost no improvement.

According to the research of the inventor, it is believed that this problem is related to the photoresist suitable for the manufacture of display devices. Specifically, the photoresist (positive photoresist) used in the manufacture of display devices is different from the photoresist used in the manufacture of semiconductor devices and has a higher sensitivity. Therefore, the corresponding film reduction is not avoided even at relatively low doses, and it is easy to cause local film thickness loss in unexpected parts.

Furthermore, the interaction between the main pattern 1 and the auxiliary pattern 2 generated in the mask of Reference Example 3 is to use the optical image formed by the light of the inverted phase transmitted through the auxiliary pattern 2 to improve the optical image generated by the transmitted light of the main pattern 1. The phenomenon of peak light intensity. Moreover, the excellent transfer performance (DOF, MEEF) shown in Figure 3 was obtained. On the other hand, the light intensity generated by the light passing through the auxiliary pattern is also slightly increased by the interaction with the main pattern 1. It can be considered that the photoresist used in the manufacture of display devices has a high sensitivity, so except for the case where the auxiliary patterns 2 are close to each other, if the auxiliary patterns 2 If shared by a plurality of main patterns 1, there is a risk that the transmitted light of the auxiliary pattern 2 will reduce the thickness of the resist on the transferred body.

On the other hand, in Example 1 of FIG. 11(f), one of the eight sections constituting the regular octagonal band surrounding the first main pattern 1a is defective, and one of the sections facing the second main pattern 1b side is defective. The remaining 7-segment auxiliary patterns 2a are arranged around the first main pattern 1a. That is, it is set as the shape of the auxiliary pattern 2a in which the segment of the regular octagonal band surrounding the periphery of the first main pattern 1a and the portion of the regular octagonal band surrounding the periphery of the second main pattern 1b that is closest to and facing each other is missing . In the same manner as for the second main pattern 1b, a segment facing the side of the first main pattern 1a is cut off, and an auxiliary pattern 2b having the remaining 7 segments is arranged around the second main pattern 1b.

Furthermore, when the segment of the auxiliary pattern is defective, it is not necessary to cut according to the boundary line of the segment shown in FIG. 8, for example, as shown in FIG. 7(a), as long as the main part of the segment is defective at least can. Regarding the area of the defective part, it is preferable, for example, that if one of the eight segments is defective, it will be 80% or more of the area of one segment, and set it as the defective segment More than 80% of the area of the quantity. At this time, there is a portion between the two main patterns that only interposes the low light transmission portion 3, and the straight line connecting the centers of gravity of the two main patterns 1a, 1b does not pass through the auxiliary pattern.

In this way, it can be seen that when the adjacent sections of the auxiliary patterns of the two main patterns are defective, the loss of the resist film thickness becomes zero in the formed resist pattern, and the loss is greatly reduced. And can get a significant effect. In addition, it can be seen that the same effect is in the case where the two main patterns 1a and 1b are further approached as in Example 2 of Figure 11(g) or Example 3 of Figure 11(h) (Pitch P=8μm, P=7.5 In the case of μm) can also be obtained. The cross-sectional structure of the resist pattern in this case is the same as in FIG. 9.

However, in the embodiment of Fig. 11(f)~(i), although the same exposure dose as the above reference examples 4~8 is applied, the diameter of the hole pattern transferred to the resist film is slightly changed from the initial target size small. Specifically, in Example 1, with respect to the initial target size of 1.5 (μm), X-CD (diameter in X direction) becomes 1.39 (μm), and Y-CD (diameter in Y direction) becomes 1.37 (μm). Therefore, in order to form the hole pattern so that the X-CD and Y-CD on the transfer body are both close to the target size (1.5 μm), it is preferable to make the mask deviation β1 larger than 0.5 μm.

Furthermore, in order to make the X-CD and Y-CD on the transfer target equally the target size (1.5 μm), it is preferable to provide appropriate mask deviation β2 in the X direction and the Y direction.

Therefore, as shown in Fig. 12, in the embodiment of Fig. 11(f)~(h), by assigning appropriate mask deviation β2(x), β2(y) to the CD on the mask, the result is On the transfer body, both X-CD and Y-CD achieved the target size of 1.5 μm.

Moreover, as a result, it can be seen that in the case of the mask of the embodiment in Fig. 11(f)~(h), the DOF (depth of focus) value (24) is compared with the binary mask of Reference Example 1 (Fig. 2(a)) ) Or the halftone phase shift mask of Reference Example 2 (Figure 2(b)) is large, and can stably form a hole pattern of the required diameter on the transferred body. In addition, since the Eop dose required for exposure is smaller than that of the binary mask of Reference Example 1 or the halftone type phase shift mask of Reference Example 2, the exposure step can be performed efficiently.

Furthermore, in the embodiment of Fig. 11(f)~(h), the eight sections of the auxiliary pattern 2a attached to the first main pattern 1a and the eight sections of the auxiliary pattern 2b attached to the second main pattern 1b One of the segments facing each other is defective. That is, for one main pattern 1, the number of segments of the auxiliary pattern 2 is set to 7. On the other hand, when the two main patterns 1a and 1b are further arranged close to each other, it is also possible to center the defective section, and to further deficient the sections located on both sides thereof. For example, in the embodiment 4 of FIG. 11(i), the section A of the eight sections of the auxiliary pattern 2a attached to the first main pattern 1a, and the sections B and H located on both sides of the section A are missing, In addition, the section E of the eight sections of the auxiliary pattern 2b attached to the second main pattern 1b, and the sections D and F located on both sides of the section E are defective, thereby reducing the loss of the resist film thickness. Set to zero. As a result, here, one main pattern 1 is missing three segments, whereby the number of segments of the auxiliary pattern 2 is set to five. Furthermore, the number of main patterns arranged close to each other is not limited to two, and more hole formation patterns can be arranged at a close distance. In this case, the segment defect can also be designed in the same manner as described above.

In a pattern group that includes a plurality of main patterns (respectively close to at least any other) in a close arrangement, when the number of main patterns included is set to N, and the total number of sections of the auxiliary pattern is set to K, you can Set K≦(8-1)N.

Furthermore, in FIGS. 11(f) to (i), only the case where the second main pattern 1b approaches the first main pattern 1a in the X direction (the left and right directions in the figure) is illustrated, but it approaches it in the Y direction. In this case, it is also possible to arrange the auxiliary pattern 2 to make any one of the eight segments missing in the same manner as described above.

Furthermore, the present invention can also be effectively applied when the second main pattern 1b approaches the first main pattern 1a in the diagonal direction of the autonomous pattern 1, such as when approaching from the oblique direction. In this case, at least one of the eight sections of the auxiliary pattern 2a attached to the first main pattern 1a that faces the second main pattern 1b may be defective.

In addition, when the third main pattern and the fourth main pattern are arranged close to the first main pattern, in the same manner as described above, the eight segments of the auxiliary patterns attached to each main pattern may be aligned with each other. The segment to the side is defective. In this case, according to the relative arrangement of a plurality of main patterns, in addition to the main pattern with seven-segment auxiliary pattern and the main pattern with five-segment auxiliary pattern, there may also be six-segment and four-segment , The main pattern of the auxiliary pattern of three sections, two sections, and then one section.

For example, it can be set as a pattern group in which two main patterns each have an auxiliary pattern that is missing one segment one by one, or a pattern group that has three auxiliary patterns that are missing three segments one by one.

Alternatively, three main patterns can be set as a pattern group in which the auxiliary patterns of 1 or 2 segments are missing according to their arrangement (X direction, Y direction, or X and Y directions, the same below). Furthermore, it is also possible to set as a pattern group in which the four main patterns have auxiliary patterns with 1 to 5 segments missing according to their arrangement.

Hereinafter, it can also be set as a pattern group with 5 or 6 or 7 main patterns having auxiliary patterns with defects of 1 to 6 segments according to their arrangement, or set as 8 main patterns having defects of 1 to 7 according to their arrangement. The pattern group of the auxiliary pattern of the segment.

On the other hand, the auxiliary pattern of one main pattern can be set to have no defect except for the section facing the side of the other main pattern or the sections on both sides thereof.

Moreover, the diameter of the hole pattern formed on the to-be-transferred body may become a different value in the X direction and the Y direction according to the approach direction of a plurality of hole formation patterns. The reason is that the optical image changes caused by the defect of a part of the auxiliary pattern are unevenly generated in the X direction and the Y direction. Therefore, for the purpose of compensating for the influence of the uneven optical image in the X direction and the Y direction, it is more useful to provide the pattern drawing data with a mask deviation β2 of different sizes in the X direction and the Y direction.

For example, as shown in FIG. 7(a) above, the first main pattern 1a and the second main pattern 1b are arranged in the X direction, and the auxiliary patterns 2a and 2b attached to the two main patterns 1a and 1b face each other When the segment (that is, the segment extending in the Y direction) is defective, the mask deviation β2 (μm) given to the size of the first main pattern 1a and the second main pattern 1b is given to the X direction When the amount is set to β2(x) and the amount given in the Y direction is set to β2(y), it can be set as β2(y)>β2(x).

Specifically, in autonomous pattern observation, a positive deviation β2( y). Furthermore, if necessary, a negative deviation β2(x) may be given to the direction (X direction in FIG. 7(a)) where the defect portion of the auxiliary pattern exists.

An example of a transfer pattern including the main patterns 1a and 1b provided with the mask deviation β2 in this way is shown in FIG. 13. Here, as a result of applying the mask deviation β2, the X-direction dimensions of the main patterns 1a and 1b are smaller than the Y-direction dimensions, and the shapes of the main patterns 1a and 1b are elongated rectangles.

In the embodiment of Figure 11(g), the hole pattern formed on the transferred body as the transfer image of the square main pattern 1a, 1b becomes a horizontally long rectangle (X-CD=1.40μm, Y-CD =1.37μm). Therefore, if the shapes of the main patterns 1a, 1b are set to be elongated rectangles by applying the mask deviation, the error of the pattern size caused by the defect of a part of the auxiliary patterns 2a, 2b can be eliminated. As a result, it is possible to form a hole pattern whose size in the X direction and the size in the Y direction are equal to the transferred body.

Therefore, by optical simulation, for each of the X direction and the Y direction, it is only necessary to obtain the deviation β2 for the size of the X direction and the Y direction to be equal on the transferred body, and reflect it in the pattern drawing data. .

Therefore, among the transfer patterns of the photomask, the main pattern to which the deviation β2 is provided becomes a rectangle. That is, the first main pattern becomes a rectangle with long sides on the side facing the second main pattern at the close position.

As for the arrangement example in Figure 13 above, the long side W3(y) of the main pattern becomes W3(y)=W1+β2(y), and the short side W3(x) becomes W3(x)=W1+β2(x) ). Furthermore, W3(x) and W3(y) preferably satisfy the following formula.

For the long side, 0.8≦W3(y)≦4.0, more preferably 1.0≦W3(y)<3.5, for the short side, 0.8≦W3(x)≦4.0, more preferably 1.0≦W3(x)≦3.0 .

As described above, when the photomask of this embodiment is used as a photomask for manufacturing a display device At this time, that is, when the photomask of the present embodiment is used in combination with the photoresist for manufacturing the display device, the loss of the resist film thickness of the portion corresponding to the auxiliary pattern on the transferred body can be greatly reduced.

<Manufacturing Method of Mask>

Next, an example of a method of manufacturing a photomask applicable to the embodiment of the present invention will be described below with reference to FIGS. 14(a) to (f). Furthermore, in FIGS. 14(a) to (f), the left side shows a cross-sectional view, and the right side shows a plan view. For simplicity, the mask pattern shape only shows the first main pattern and the auxiliary patterns attached to the first main pattern.

First, as shown in FIG. 14(a), a photomask substrate 30 is prepared. In the photomask base 30, a phase shift film 11 and a low-transmittance film 12 are sequentially formed on a transparent substrate 10 including glass or the like, and a first photoresist film 13 is further coated.

The phase shift film 11 is formed on the main surface of the transparent substrate 10. When the phase shift film 11 sets any one of the i-line, h-line, and g-line as the representative wavelength of the exposure light, the transmittance T1 (%) for the representative wavelength is preferably 20 to 80 (%), It is more preferably 30 to 75 (%), and still more preferably 40 to 75 (%). In addition, the phase shift amount of the phase shift film 11 with respect to the above-mentioned representative wavelength is approximately 180 degrees. With this phase shift film 11, the phase difference of the transmitted light between the main pattern including the light-transmitting portion and the auxiliary pattern including the phase shifting portion can be approximately 180 degrees. Such a phase shift film 11 shifts the phase of the light of the representative wavelength in the wavelength range of the i-line to the g-line by approximately 180 degrees. As a film formation method of the phase shift film 11, well-known methods, such as a sputtering method, can be applied.

Preferably, the phase shift film 11 satisfies the above-mentioned transmittance and phase difference, and is formed of a material capable of wet etching as described below. However, if the amount of side etching generated during wet etching becomes too large, it will cause deterioration of CD accuracy or destruction of the upper layer film due to undercutting. Therefore, the film thickness of the phase shift film 11 is preferably set to 2000 Å or less, preferably 300 ~ 2000Å, more preferably 300~1800Å.

In addition, in order to satisfy these conditions, the refractive index of the representative wavelength (for example, h-line) included in the exposure light of the material of the phase shift film 11 is preferably 1.5 to 2.9, and more preferably 1.8 to 2.4.

Furthermore, in order to fully exhibit the phase shift effect, it is preferable that the cross section of the pattern (etched surface) obtained by wet etching is approximately perpendicular to the main surface of the transparent substrate 10.

In consideration of the above properties, as the material of the phase shift film 11, materials including any one of Zr, Nb, Hf, Ta, Mo, Ti and Si or oxides, nitrides, and oxynitrides including these materials can be used. Materials, carbides, or carbon and nitrogen oxides.

A low light transmission film 12 is formed on the phase shift film 11. As a film forming method of the low light-transmitting film 12, as in the case of the phase shift film 11, a known method such as a sputtering method can be applied. Furthermore, it is preferable that the wavelength dependence of the phase shift amount of the phase shift film 11 with respect to the i-line, h-line, and g-line has a fluctuation range within 40 degrees.

The low light-transmitting film 12 may include a light-shielding film that does not substantially transmit exposed light. Furthermore, in addition to this, the low light-transmitting film 12 may be formed of a film having a specific low transmittance for the representative wavelength of the exposed light. The low-transmittance film 12 used in the manufacture of the photomask of this embodiment has a transmittance T2 that is lower than the transmittance T1 (%) of the phase shift film 11 for the light of the representative wavelength in the wavelength range of the i-line to the g-line. (%).

When the low-transmittance film 12 transmits the exposed light with a low transmittance, the low-transmittance film 12 is required to have the low transmittance and phase shift of the exposure light to reach the low transmittance of the photomask of the cost embodiment. The transmittance and phase shift of the light part. Preferably, in the layered state of the phase shift film 11 and the low-transmittance film 12, the transmittance T3 (%) for the light of the representative wavelength of the exposed light is T3≦20, and the phase shift amount Φ3 is better It is 90 (degrees) or less, more preferably 60 (degrees) or less.

As a separate property of the low light transmission film 12, it is preferable that the above-mentioned representative wavelength is not substantially The light-transmitting person may have a transmittance (T2 (%)) less than 30 (%) (ie, 0<T2<30), and the phase shift amount (Φ2) is approximately 180 degrees. The so-called approximately 180 degrees means 120 to 240 degrees. Preferably, the phase offset Φ2 is 150 to 210 (degrees).

The material of the low light transmission film 12 can be Cr or its compound (oxide, nitride, carbide, oxynitride, or oxycarbonitride), or it can also be a metal containing Mo, W, Ta, and Ti. Silicide or the above-mentioned compound of the silicide. However, the material of the low light-transmitting film 12 is preferably a material that can be wet-etched in the same manner as the phase shift film 11 and has etching selectivity to the material of the phase shift film 11. That is, it is preferable that the low light transmission film 12 has resistance to the etchant of the phase shift film 11, and the phase shift film 11 has resistance to the etchant of the low light transmission film 12.

The first photoresist film 13 is coated on the low light transmission film 12. The photomask of this embodiment is preferably drawn by a laser drawing device, and therefore is set as a photoresist suitable for the laser drawing device. The photoresist constituting the first photoresist film 13 may be a positive type or a negative type, but the following description is made as a positive type photoresist.

Next, as shown in FIG. 14(b), for the first photoresist film 13, a drawing device is used to perform drawing using drawing data based on a transfer pattern (first drawing). Then, using the first resist pattern 13p obtained by development as a mask, the low-light-transmitting film 12 is wet-etched, thereby forming the low-light-transmitting film pattern 12p. At this stage, the area of the low light transmission part is defined, and the area of the auxiliary pattern (the low light transmission film pattern 12p) surrounded by the low light transmission part is defined. As the etching solution (wet etchant) used for wet etching, a known one suitable for the composition of the low light transmission film 12 used can be used. For example, if the low light-transmitting film 12 is a film containing Cr, as the wet etchant, cerium ammonium nitrate or the like can be used.

Next, as shown in FIG. 14(c), the first resist pattern 13p is peeled off. Thereby, the low light-transmitting film pattern 12p and a part of the phase shift film 11 are exposed.

Next, as shown in FIG. 14(d), a second photoresist is applied to the entire surface including the low-transmittance film pattern 12p 膜14。 Film 14.

Next, as shown in FIG. 14(e), after the second drawing is performed on the second photoresist film 14, the second resist pattern 14p is formed by development. Next, using the second resist pattern 14p and the low light-transmitting film pattern 12p as a mask, the phase shift film 11 is wet-etched. By this etching (development), the main surface of the transparent substrate 10 is exposed as a light-transmitting portion, thereby delimiting an area including the main pattern of the light-transmitting portion.

Furthermore, the second resist pattern 14p covers the area that becomes the auxiliary pattern and has an opening in the area including the main pattern of the light-transmitting portion. In this case, it is preferable to size the drawing data of the second drawing in such a way that the edge portion of the low light-transmitting film pattern 12p is exposed on the inner side of the opening edge of the second resist pattern 14p. In this way, the misalignment generated between the first drawing and the second drawing can be absorbed, and the CD accuracy of the transfer pattern can be prevented from deteriorating.

That is, if the second resist pattern 14p is dimensioned during the second drawing, when it is desired to form an isolated hole pattern on the transferred body, the phase shift film 11 and the low light transmission film will not be used. Position shift occurs during patterning of 12. Therefore, in the transfer pattern as illustrated in FIG. 1, the center of gravity of the main pattern 1 and the auxiliary pattern 2 can be precisely aligned.

The wet etchant used for the etching of the phase shift film 11 is appropriately selected according to the composition of the phase shift film 11.

Next, as shown in FIG. 14(f), the second resist pattern 14p is peeled off. In this way, a photomask with a pattern for transfer is completed. Furthermore, FIG. 14 shows the formation of a regular octagonal auxiliary pattern with no segment defect, but when any one of the eight segments is missing, it is as long as shown in FIG. 14(b) When defining the area of the auxiliary pattern, the drawing data can be changed according to the position and size of the segment to be defective.

In the manufacture of the above-mentioned photomask, dry etching or wet etching is included in the etching that can be applied when patterning optical films such as the phase shift film 11 or the low-transmittance film 12. Any of them can be used However, in the present invention, wet etching is particularly advantageous. The reason is that the size of the mask for manufacturing the display device is relatively large, and furthermore, there are multiple sizes. When manufacturing this type of photomask, if dry etching that requires a vacuum chamber is applied, the dry etching device will be enlarged or the efficiency of the manufacturing steps will be reduced.

However, there is also a problem associated with the application of wet etching when manufacturing such photomasks. Wet etching has the property of isotropic etching. Therefore, when a specific film is etched in the depth direction to dissolve it, etching is also performed in a direction perpendicular to the depth direction. For example, when the phase shift film 11 with a film thickness of F (nm) is etched to form a slit, the opening of the resist pattern that becomes the etching mask is 2F (nm) smaller than the required slit width (that is, one side F(nm)), but the narrower 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 above-mentioned film thickness F (nm) is large, the amount of side etching also becomes large. Therefore, it is advantageous to use a film material having a phase shift amount of approximately 180 degrees even if the film thickness is small. Therefore, it is desirable that the refractive index of the phase shift film 11 is relatively high for the representative wavelength of the exposure light. Specifically, it is preferable to use a material having a refractive index of preferably 1.5 to 2.9, and more preferably 1.8 to 2.4 for the above-mentioned representative wavelength to form the phase shift film 11.

The present invention includes a method of manufacturing a display device, which includes a step of applying the photomask of the present embodiment to expose with an exposure device, and transferring the above-mentioned transfer pattern on the transfer body.

The manufacturing method of the display device of the present invention first prepares the photomask of this embodiment. Next, an exposure device with a numerical aperture (NA) of 0.08~0.15 and an exposure light source including i-line, h-line, and g-line is used to expose the above-mentioned transfer pattern, and the diameter W2 is formed on the transferred body 0.8~3.0(μm) hole pattern. Normally, equal magnification exposure is suitable for exposure, which is more advantageous.

When using the mask transfer pattern of this embodiment, reduction exposure can also be used. However, as an exposure machine for the mask used in the manufacture of display devices, it is a method of equal magnification projection exposure, preferably the following By.

For example, the numerical aperture (NA) of the optical system is preferably 0.08≦NA<0.20, more preferably 0.08≦NA≦0.15, and more preferably 0.08<NA<0.15. In addition, the coherence factor σ is 0.4≦σ≦0.9, more preferably 0.4<σ<0.7, and still more preferably 0.4<σ<0.6.

The exposure light source is a light source that includes at least one of i-line, h-line, and g-line in the exposure light. When applying a single wavelength of exposure light, it is better to use the i-line. On the other hand, it is more useful to use a light source that includes i-line, h-line, and g-line (also known as a wide-wavelength light source) to ensure sufficient light.

In addition, the light source of the exposure device used can also use oblique illumination (ring illumination, etc.), but by using normal illumination that is not suitable for oblique illumination, the excellent effects of the present invention can be fully obtained.

According to the present invention, in a method of manufacturing a display device using a mask for manufacturing a display device, even if it is a fine dense pattern, it is possible to stably perform transfer to the transfer target body. Specifically, it is possible to precisely form hole patterns while ensuring the process margin during manufacturing such as DOF or MEEF. Furthermore, when a dense pattern is formed, the thickness of the resist pattern formed on the object to be transferred can be sufficiently ensured. It improves the accuracy of CD in the production of display devices and provides industrial benefits such as stable production and high yield.

1a‧‧‧Main pattern

1b‧‧‧Main pattern

2a‧‧‧Auxiliary pattern

2b‧‧‧Auxiliary pattern

3‧‧‧Low transmittance

d‧‧‧Width of auxiliary pattern 2

L‧‧‧Slit pitch

P‧‧‧Hole spacing

S‧‧‧area

W1‧‧‧Width of pattern 1

X‧‧‧direction

Y‧‧‧ direction

Claims (20)

A photomask for manufacturing a display device, characterized in that it has a pattern for transfer on a transparent substrate, the pattern for transfer includes: a main pattern including a quadrangular light-transmitting part; and an auxiliary pattern, which is arranged on the above The periphery of the main pattern, and includes a phase shift part; and a low-transmittance part, which is formed in the area outside the main pattern and the auxiliary pattern; a positive eight with a specific width that surrounds the main pattern in the periphery of the main pattern In the case of a polygonal belt, the auxiliary pattern constitutes at least a part of the regular octagonal belt, and when one of the plurality of main patterns included in the transfer pattern is set as the first main pattern, it is the same as the first main pattern The different second main pattern is arranged at a position close to the first main pattern, and one of the eight sections of the regular octagonal band that surrounds the first main pattern has a section facing the second main pattern. The defective auxiliary pattern is arranged on the periphery of the first main pattern. The photomask for manufacturing a display device according to claim 1, wherein the pattern for transfer is a hole pattern formed on the body to be transferred. The photomask for manufacturing a display device of claim 1, wherein when the diameter of the main pattern is set to W1, the transfer pattern forms a hole pattern of diameter W2 on the body to be transferred as the transfer image of the main pattern , And W1≧W2. For example, in the photomask for display device manufacturing of claim 3, the deviation value β1 is: β1=W1-W2≧0, and when the unit of β1, W1, and W2 is μm, 0.2≦β1≦1.0 is satisfied. The photomask for manufacturing a display device according to any one of claims 1 to 3, wherein the transfer pattern includes three or more of the main patterns in the X direction, the Y direction perpendicular to the X direction, or the X direction and The dense pattern arranged regularly in the Y direction, and each of the main patterns constituting the dense pattern has the auxiliary pattern formed by deficiencies in at least one of the eight sectors facing the other main pattern side . The photomask for manufacturing a display device according to any one of claims 1 to 3, wherein the phase shift portion is formed on the transparent substrate with a transmittance T1 of 20 to 80% for the representative wavelength of the light to be exposed A phase shift film in which the phase of the exposure light is shifted by approximately 180 degrees. The above-mentioned so-called approximately 180 degrees is in the range of 120 to 240 degrees. The mask for manufacturing a display device according to any one of claims 1 to 3, wherein the main pattern and the auxiliary pattern are each surrounded by a low light transmission portion. The photomask for manufacturing a display device according to any one of claims 1 to 3, wherein the low light-transmitting portion is a light-shielding portion having an optical density OD of exposed light of 2 or more. The photomask for manufacturing a display device according to any one of claims 1 to 3, wherein the transmittance of the low light transmission portion to the representative wavelength of the exposed light exceeds 0% and 20% or less. For example, the mask for manufacturing a display device according to any one of claims 1 to 3, wherein the diameter of the main pattern is W1, and the unit of W1 is μm, 0.8≦W1≦4.0. Such as the photomask for manufacturing a display device according to any one of claims 1 to 3, wherein the width of the auxiliary pattern is set to d and the unit of d is set to μm, d≧0.7. The photomask for manufacturing a display device according to any one of claims 1 to 3, wherein the phase shift portion has a transmittance T1 with respect to a representative wavelength of exposed light, the width of the auxiliary pattern is set to d, and the unit of d is When it is μm and the unit of T1 is %, the relationship of the following formula (1) is established:

The photomask for manufacturing a display device according to any one of claims 1 to 3, wherein the distance between the center of the main pattern and the center of the auxiliary pattern in the width direction is the slit pitch L, and the unit of the L is μm When, 1.0<L≦5.0. The photomask for manufacturing a display device according to any one of claims 1 to 3, wherein the distance between the center of gravity of the first main pattern and the second main pattern is set to a hole pitch P, and the unit of the hole pitch P is set to μm When, P≧1.6. For example, the mask for manufacturing a display device of claim 1 or 2, wherein when the arrangement direction of the first main pattern and the second main pattern is set to the X direction, the size of the first main pattern in the X direction is smaller than that of the first main pattern. For the size of the pattern in the Y direction, the Y direction is the direction perpendicular to the X direction. The photomask for manufacturing a display device according to any one of claims 1 to 3, wherein in the transfer pattern, a section of the auxiliary pattern having a defect is the center, and the sections on both sides are further defective. For example, the photomask for manufacturing a display device according to any one of claims 1 to 3, which is a photomask for transferring the above-mentioned pattern for transfer with an exposure machine with a numerical aperture NA of an optical system of 0.08≦NA<0.20. The photomask for manufacturing a display device according to any one of claims 1 to 3, which is a photomask used for transferring the above-mentioned pattern for transfer by an exposure machine of an equal-magnification projection exposure method. The photomask for manufacturing a display device according to any one of claims 1 to 3, which is a photomask used for transferring the above-mentioned transfer pattern with an exposure machine whose coherence factor σ of the optical system is 0.4≦σ≦0.9. A method for manufacturing a display device, which includes the following steps: preparing a photomask as in any one of claims 1 to 6; and using a numerical aperture NA that satisfies 0.08≦NA<0.20 and includes i-line, h-line, and g-line The exposure device of at least any one of the exposure light sources exposes the above-mentioned transfer pattern to form a hole pattern with a diameter W2 of 0.8 to 3.0 μm on the transferred body.

Images