阅读说明：本技术 光掩模及其制造方法、图案转印方法、显示装置的制造方法 (Photomask, method for manufacturing photomask, method for transferring pattern, and method for manufacturing display device ) 是由 吉田光一郎 于 2014-11-17 设计创作，主要内容包括：本发明提供一种光掩模及其制造方法、图案转印方法、显示装置的制造方法。所述光掩模具有用于在被转印体上形成线宽Wp的器件图案的转印用图案,器件图案的线宽Wp与构成转印用图案的第1空白图案的线宽Wm之间的关系满足下述式(1)和式(2)：Wp＜10μm…(1)1≤(Wm－Wp)/2≤4(μm)…(2)。(The invention provides a photomask, a manufacturing method thereof, a pattern transfer method and a manufacturing method of a display device. The photomask has a transfer pattern for forming a device pattern having a line width Wp on a transferred body, and the relationship between the line width Wp of the device pattern and the line width Wm of a1 st blank pattern constituting the transfer pattern satisfies the following expressions (1) and (2): wp is less than 10 μm … (1), 1 is less than or equal to (Wm-Wp)/2 is less than or equal to 4(μm) … (2).)

1. A photomask for proximity exposure, which is a photomask for manufacturing a display device and has a transfer pattern for forming a device pattern having a line width Wp on a transferred object,

the transfer pattern has:

a light-shielding region in which at least a light-shielding film is formed on a transparent substrate; and

a semi-transmissive portion corresponding to the device pattern, the semi-transmissive portion being adjacent to the light-shielding region and having a line width Wm arranged so as to be sandwiched from both sides by the light-shielding region,

the semi-light-transmitting part is formed by forming a semi-light-transmitting film on the transparent substrate,

the exposure light transmittance of the semi-transparent film is 20-60%,

a relationship between a line width Wp of the device pattern and a line width Wm of the semi-light transmitting portion satisfies the following equations 1 and 2:

wp < 10 μm … formula 1

1.0 mu m-Wp)/2 is 3.0 mu m- … formula 2.

2. The photomask according to claim 1, wherein the transfer pattern has a plurality of the semi-light transmitting portions, and the semi-light transmitting portions have a line shape with a line width Wm.

3. The photomask according to claim 2, wherein a portion where the light shielding region having a width of 3 xWm or more is interposed between the semi-light transmitting portions adjacent in the width direction of the line shape.

4. The photomask of claim 2, wherein the transfer pattern has a light-transmitting portion.

5. The photomask according to claim 4, wherein a phase difference between the transmitted light of the semi-light transmitting portion and the light transmitting portion is 90 degrees or less.

6. The photomask according to claim 4, wherein a phase difference between the transmitted light of the semi-light transmitting portion and the transmitted light of the light transmitting portion is 60 degrees or less.

7. The photomask according to claim 5, wherein the transfer pattern has a light-transmitting portion in a line shape having a line width Wn, wherein Wn > Wm.

8. The photomask of claim 7, wherein 10 μm ≦ Wn.

9. The photomask according to any one of claims 1 to 8, wherein the light-shielding region is formed by sequentially laminating the semi-light-transmissive film and the light-shielding film on the transparent substrate.

10. The photomask of any of claims 1 to 8, wherein the transfer pattern is used for black matrix or black stripe fabrication.

11. The photomask of any of claims 1 to 8, wherein the transfer pattern is used in color filter fabrication.

12. The photomask according to any one of claims 1 to 8, wherein the line width Wp of the device pattern satisfies 3 μm ≦ Wp ≦ 8 μm.

13. The photomask according to any one of claims 1 to 8, wherein the line width Wp of the device pattern satisfies 4 μm ≦ Wp ≦ 7 μm.

14. The photomask of any of claims 1 to 8, wherein the transfer pattern is used for photo spacer fabrication.

15. The photomask according to any one of claims 1 to 8, wherein light-shielding regions having a predetermined shape are regularly arranged in the transfer pattern.

16. The photomask according to any one of claims 1 to 8, wherein the pattern for transfer is a pattern applied to exposure to a negative photosensitive material.

17. The photomask according to any one of claims 1 to 8, wherein the photomask is a photomask for proximity exposure in which the proximity gap is in the range of 10 to 200 μm.

18. A method of manufacturing a photomask for proximity exposure, the photomask being a photomask for manufacturing a display device and having a pattern for transfer for forming a device pattern having a line width Wp on a transferred object, the method comprising:

forming a photomask blank having formed thereon an optical film including at least a light-shielding film on a transparent substrate, subjecting the optical film to a photolithography step, and then patterning the optical film by wet etching to form the transfer pattern,

the transfer pattern has:

a light-shielding region in which at least a light-shielding film is formed on the transparent substrate; and

a semi-transmissive portion corresponding to the device pattern, the semi-transmissive portion being adjacent to the light-shielding region and having a line width Wm arranged so as to be sandwiched from both sides by the light-shielding region,

the semi-light-transmitting part is formed by forming a semi-light-transmitting film on the transparent substrate,

the exposure light transmittance of the semi-transparent film is 20-60%,

a relationship between a line width Wp of the device pattern and a line width Wm of the semi-light transmitting portion satisfies the following equations 1 and 2:

wp < 10 μm … formula 1

1.0 mu m-Wp)/2 is 3.0 mu m- … formula 2.

19. A pattern transfer method for forming a device pattern of a line width Wp on a transferred object using a photomask having a pattern for transfer, the pattern transfer method being characterized in that,

the negative photosensitive material film formed on the transferred body is exposed using a proximity exposure apparatus using the photomask according to any one of claim 1 to claim 17.

20. A manufacturing method of a display device, characterized in that the manufacturing method uses the pattern transfer method of claim 19.

Technical Field

The present invention relates to a photomask having a pattern for transfer, a method for manufacturing the photomask, a method for transferring a pattern using the photomask, and a method for manufacturing a display device.

Background

In recent years, in the manufacture of Display devices such as Liquid Crystal Display devices (LCD), high transfer accuracy has been demanded in association with the improvement in production efficiency due to the increase in size of photomasks used. The liquid crystal display device has such a structure: a TFT substrate on which a Thin Film Transistor (TFT) array is formed is bonded to a color filter on which an RGB pattern is formed, and liquid crystal is sealed therebetween.

Fig. 1A to 1C are schematic views showing an example of a color filter. As shown in fig. 1A to 1C, the color filter includes: a colored portion 101 that selectively transmits only light of a specific wavelength, and a black matrix (black matrix)102 (light shielding portion) that shields light. The colored portion 101 is colored in each color of red, green, and blue (RGB). Fig. 1A shows a stripe (stripe) arrangement of color filters, and fig. 1B shows a mosaic (mosaic) arrangement of color filters. Also, FIG. 1C shows a schematic cross-sectional view of line A-A of FIG. 1A or line B-B of FIG. 1B.

When a black matrix layer or each colored layer is formed on a light-transmissive substrate using a photomask, it is most advantageous to apply proximity (proximity) exposure. This is because, compared with the proximity exposure (projection) exposure, the exposure apparatus does not need a complicated optical system in its structure, and the apparatus cost is low, thereby improving the production efficiency.

Fig. 2 is a schematic diagram showing an exposure apparatus that performs proximity exposure. As shown in fig. 2, an exposure apparatus 110 for performing proximity exposure includes: a light source 111, an elliptical mirror 112 functioning as a condenser, an integrator 113, and a collimating lens (collimating lens) 114. As the light source 111, a mercury lamp or the like having a wavelength region including i-line, h-line, and g-line is generally used.

In the exposure device 110, a light beam emitted from a light source 111 passes through an elliptical mirror 112, an integrator 113, and a collimator lens 114 to become a light beam of uniform illuminance. Then, the light beam is irradiated to the photomask 120. The light beam transmitted through the photomask 120 exposes the photosensitive material film on the work of the transfer object 121 disposed with a predetermined proximity gap (pg) from the photomask 120.

In this way, during the proximity exposure, the object 121 to be transferred on which the photosensitive material film is formed is horizontally placed on a stage (not shown), and the photomask 120 is held so that the pattern surface 120a on which the transfer pattern is formed faces the object 121. Then, the pattern is transferred onto the photosensitive material film of the object 121 by irradiating light from the back surface side of the photomask 120. At this time, a predetermined interval (proximity gap) is provided between the photomask 120 and the transferred body 121.

In general, when a photomask is installed in a proximity exposure apparatus, a region (also referred to as a pattern region) where a transfer pattern is formed is held by a holding member of the exposure apparatus on a main surface where the transfer pattern is formed. That is, the holding member of the exposure apparatus is brought into contact with the vicinity of the opposing 2 sides or 4 sides constituting the outer periphery of the rectangular photomask, thereby holding the photomask. Then, the photomask is placed on the exposure apparatus in a substantially horizontal posture while maintaining a predetermined proximity gap.

In addition, when proximity exposure is applied, there are problems as follows: in transfer, it is difficult to perform distortion correction using optical means, and transfer accuracy is easily degraded compared to projection exposure.

For example, since the photomask is deflected by its own weight, the deflection of the photomask is corrected to some extent by using a holding mechanism of the exposure apparatus. For example, patent document 1 describes the following method: in a supporting mechanism for horizontally supporting a flat-plate-shaped mask, a predetermined pressure is applied from above the mask to the outside of a supporting point of a holding member for supporting the photomask from below, thereby correcting deflection.

Patent document 2 describes a photomask blank for reducing variations caused by the position close to the gap when the photomask blank is mounted on a proximity exposure apparatus and used.

[ patent document 1 ] Japanese patent application laid-open No. 9-306832

[ patent document 2 ] Japanese patent laid-open No. 2012 and 256798

However, the present inventors have found that even though it is useful to reduce the influence of the pattern transfer due to the flexure of the photomask, it is not sufficient to manufacture a precise display device for the above-mentioned application only in this respect.

For example, it is known that the main surface of the photomask substrate is deformed due to the different directions and magnitudes of the forces to which the photomask is subjected by the holding system of the photomask or the holding mechanism for reducing the flexure. Further, it is almost impossible to completely suppress the in-plane variation of the proximity gap due to the flatness of the stage of the exposure apparatus, the thickness distribution of the transferred body placed on the stage of the exposure apparatus, and the like. Patent document 2 describes a method of reducing such in-plane variation of the proximity gap by using the shape of the photomask substrate. However, there is a problem that the in-plane variation of the proximity gap differs for each exposure apparatus used.

In the proximity exposure, when the in-plane deviation of the proximity gap occurs, it is more difficult to transfer the blank pattern (pull き パ タ ー ン) having a fine line width. This is because diffraction of light occurs at the edge (edge) of the slit-shaped blank pattern, and the influence of the diffraction and interference increases to a non-negligible extent as the width of the blank pattern becomes finer.

Fig. 3 is a diagram illustrating a light intensity distribution caused by interference due to transmitted light in proximity exposure. In fig. 3, the photomask 120 provided with the blank pattern is disposed such that the pattern surface 120a faces the object 121 to be transferred. At this time, an approach gap pg is provided between the photomask 120 and the transferred body 121.

Curve 122 schematically represents a light intensity curve due to an interference pattern formed by transmitted light when light is irradiated from the back side of the photomask 120. As shown in fig. 3, diffraction of light is generated in the edges of the blank pattern in the pattern surface 120a, forming a complex interference pattern.

In proximity exposure, gaps of different sizes are generated depending on the positions in the plane, different diffraction patterns corresponding to the gaps are generated, and the line width and the light irradiation amount of the formed pattern tend to vary. However, it is not easy to estimate the intensity distribution of transmitted light actually received by the transferred body at each position in the plane.

The color filter and the TFT substrate shown in fig. 1 are manufactured by using a plurality of photomasks and applying a photolithography (photolithography) process. In recent years, with the advancement of standards such as luminance and operation speed of display devices as final products, patterns of photomasks have been miniaturized, and the requirement for line width accuracy as a result of transfer has been increasingly strict.

For example, in the black matrix for LCD, it is considered that thinning is effective for the improvement of performance currently required for LCD, that is, at least (2) to (4) of (1) operation speed, (2) luminance, (3) reduction of power consumption, and (4) high definition. Specifically, the amount of transmitted light is increased by thinning the black matrix, and thus the luminance of the LCD can be obtained. Further, if the luminance is greatly increased, power consumption of a backlight (backlight) of the LCD can be reduced. Further, by thinning the black matrix, the sharpness (sharpness) of the image can be improved.

In order to form a black matrix using a black negative photosensitive material, it is necessary to use a photomask having a pattern for transfer, in which a matrix-like blank pattern (lattice-like blank pattern) composed of an aggregate of linear blank patterns in the X direction and the Y direction is formed, in a large light-shielding region. However, it is not easy to delicately form a blank pattern of a fine width.

In the case of forming a surplus pattern formed of a linear film pattern in a large-area light-transmitting region, fine adjustment of the line width can be performed by side etching (side etching) among wet etching (wet etching) in order to obtain a desired line width. However, in the blank pattern, it is necessary to precisely determine conditions for drawing, developing, etching, and the like in advance. Further, even if the line width itself is fine, there is a disadvantage that the light transmission behavior due to the variation is greatly varied if the line width itself is fine.

Further, even when a photomask whose line width is reliably controlled is used, there is a further problem in transferring a transfer pattern to a transfer target.

When exposure is performed using a transfer pattern having a blank pattern sandwiched between light-shielding portions, the light intensity distribution on the object to be transferred is affected by light diffraction as described above as the line width of the blank pattern is reduced.

Fig. 4A and 4B are diagrams schematically showing the relationship between the line width of the blank pattern and the light intensity distribution on the transfer target. In fig. 4A and 4B, the transfer pattern is composed of a light shielding portion 103 and a blank pattern 104 sandwiched between the light shielding portion 103.

Fig. 4A shows the light intensity distribution among C-D in the case where the line width of the blank pattern 104 is a 1. Fig. 4B shows the light intensity distribution among E-F in the case where the line width of the blank pattern 104 is a2(a2 < a 1). When the line width of the blank pattern 104 is a2 < a1 as described above, when fig. 4A and 4B are compared, the peak value (peak) of the light intensity distribution at the line width a2 shown in fig. 4B is lower than the peak value of the light intensity distribution at the line width a1 shown in fig. 4A, that is, the peak value of the light intensity distribution is lower as the line width of the blank pattern 104 is smaller, and thus there is a problem that it is difficult to sufficiently sense light of the photosensitive material on the transferred body.

Disclosure of Invention

The present invention has been made in view of the above-described circumstances, and an object of the present invention is to provide a photomask, a method for manufacturing the photomask, a method for transferring a pattern, and a method for manufacturing a display device, which are capable of precisely controlling a line width and a light amount when a blank pattern having a fine line width is transferred onto a transfer target.

The photomask of the present invention has a transfer pattern for forming a device pattern (device pattern) having a line width Wp on a transferred object, and has a main surface with one side of 300mm or more, the transfer pattern including: a light-shielding region in which at least a light-shielding film is formed on a transparent substrate; and a1 st blank pattern having a line width Wm, which is a1 st blank pattern disposed so as to be surrounded by the light-shielding region, and corresponds to the device pattern, and in which a relationship between a line width Wp of the device pattern and the line width Wm of the 1 st blank pattern satisfies the following expressions (1) and (2):

Wp＜10μm…(1)

1≦(Wm－Wp)/2≦4(μm)…(2)。

according to the photomask, the line width Wm of the 1 st blank pattern in the transfer pattern of the photomask required for forming the device pattern having the line width Wp on the transferred object is adjusted to satisfy the predetermined bias (bias) amount ((Wm-Wp)/2 (μm)), so that the amount of light reaching the transferred object can be adjusted, and the CD variation of the device pattern due to the variation of the proximity gap can be suppressed. Therefore, when a blank pattern having a fine line width is transferred onto a transfer target, the line width and the light amount can be finely controlled.

In the photomask, the 1 st blank pattern may be a light-transmitting portion in which a surface of the transparent substrate is exposed.

In the photomask, the 1 st blank pattern may be a semi-transmissive portion formed by forming a semi-transmissive film on the transparent substrate.

In the photomask, the semi-transparent film may have an exposure light transmittance of 20% to 60%.

In the photomask, the transfer pattern may include a plurality of the 1 st blank patterns, each of the 1 st blank patterns may have a line shape having a line width Wm, and a portion having the light-shielding region with a width (3 × Wm) or more may be provided between the 1 st blank patterns adjacent to each other in the width direction.

Further, in the above photomask, the transfer pattern may further have a2 nd blank pattern having a line width Wn (Wn > Wm), and the 2 nd blank pattern may be formed of a light-transmitting portion.

In the photomask, the proximity gap may be in a range of 10 to 200 μm for proximity exposure.

The present invention provides a method for manufacturing a photomask having a transfer pattern for forming a device pattern having a line width Wp on a transferred object, the method comprising: forming a photomask blank having formed thereon an optical film including at least a light-shielding film on a transparent substrate, performing a photolithography process on the optical film, and then performing patterning (patterning) including wet etching to form the transfer pattern, the transfer pattern including: a light-shielding region in which at least a light-shielding film is formed on the transparent substrate; and a1 st blank pattern having a line width Wm, which is a1 st blank pattern disposed so as to be surrounded by the light-shielding region, and corresponds to the device pattern, and in which a relationship between a line width Wp of the device pattern and the line width Wm of the 1 st blank pattern satisfies the following expressions (1) and (2):

Wp＜10μm…(1)

1≦(Wm－Wp)/2≦4(μm)…(2)。

the pattern transfer method according to the present invention is a method for forming a device pattern having a line width Wp on a transfer target by proximity exposure using a photomask having a transfer pattern, and is characterized in that the photomask or the photomask manufactured by the method for manufacturing the photomask is used to expose a negative photosensitive material film formed on the transfer target with a proximity exposure apparatus.

The method for manufacturing a display device of the present invention is characterized by using the pattern transfer method.

According to the present invention, when a blank pattern having a fine line width is transferred onto a transfer target, the line width and the light amount can be finely controlled.

The invention provides a photomask for proximity exposure, which is used for manufacturing a display device and has a transfer pattern for forming a device pattern with a line width Wp on a transferred body,

the transfer pattern has:

a light-shielding region in which at least a light-shielding film is formed on a transparent substrate; and

a semi-transmissive portion corresponding to the device pattern, the semi-transmissive portion being adjacent to the light-shielding region and having a line width Wm arranged so as to be sandwiched from both sides by the light-shielding region,

the semi-light-transmitting part is formed by forming a semi-light-transmitting film on the transparent substrate,

the exposure light transmittance of the semi-transparent film is 20-60%,

a relationship between a line width Wp of the device pattern and a line width Wm of the semi-light transmitting portion satisfies the following equations 1 and 2:

wp < 10 μm … formula 1

1.0 mu m-Wp)/2 is 3.0 mu m- … formula 2.

The present invention provides a method for manufacturing a photomask for proximity exposure, the photomask being a photomask for manufacturing a display device and having a transfer pattern for forming a device pattern having a line width Wp on a transferred object, the method comprising:

forming a photomask blank having formed thereon an optical film including at least a light-shielding film on a transparent substrate, subjecting the optical film to a photolithography step, and then patterning the optical film by wet etching to form the transfer pattern,

the transfer pattern has:

a light-shielding region in which at least a light-shielding film is formed on the transparent substrate; and

a semi-transmissive portion corresponding to the device pattern, the semi-transmissive portion being adjacent to the light-shielding region and having a line width Wm arranged so as to be sandwiched from both sides by the light-shielding region,

the semi-light-transmitting part is formed by forming a semi-light-transmitting film on the transparent substrate,

the exposure light transmittance of the semi-transparent film is 20-60%,

a relationship between a line width Wp of the device pattern and a line width Wm of the semi-light transmitting portion satisfies the following equations 1 and 2:

wp < 10 μm … formula 1

1.0 mu m-Wp)/2 is 3.0 mu m- … formula 2.

The present invention provides a pattern transfer method for forming a device pattern having a line width Wp on a transfer target using a photomask having a pattern for transfer, the method being characterized in that,

the negative photosensitive material film formed on the transfer object is exposed using a proximity exposure apparatus using the photomask.

The present invention provides a method for manufacturing a display device, which is characterized by using the pattern transfer method.

Drawings

Fig. 1A is a schematic diagram showing an example of a color filter in a stripe arrangement.

Fig. 1B is a schematic diagram showing an example of a color filter in a mosaic arrangement.

FIG. 1C is a schematic cross-sectional view of line A-A of FIG. 1A or line B-B of FIG. 1B.

Fig. 2 is a schematic diagram showing an exposure apparatus that performs proximity exposure.

Fig. 3 is a diagram illustrating a light intensity distribution caused by interference due to transmitted light in proximity exposure.

Fig. 4A is a diagram showing a relationship between a line width (a1) of a blank pattern constituting a transfer pattern and a light intensity distribution on a transfer target.

Fig. 4B is a diagram showing a relationship between the line width (a2) of the blank pattern constituting the transfer pattern and the light intensity distribution on the transfer target.

Fig. 5 is a schematic view showing an example of a photomask according to one embodiment of the present invention and a transfer target to which a device pattern 1 (device pattern) is transferred using the photomask.

Fig. 6 is a schematic view showing an example of a photomask according to one embodiment of the present invention and a1 st device pattern transferred to a transfer target using the photomask.

Fig. 7 is a schematic view showing an example of a photomask according to an embodiment of the present invention and a transfer target to which a1 st device pattern and a2 nd device pattern are transferred by using the photomask.

Fig. 8 is a diagram showing an example of a black matrix manufactured using the photomask according to the above embodiment.

Fig. 9A is a diagram illustrating a part of a pixel portion of a photomask in a matrix form.

Fig. 9B is a diagram illustrating a part of a pixel portion of a matrix-shaped photomask.

Fig. 10A is a diagram showing an example of a black matrix for explaining a relationship between the device pattern formed on the transfer target and the shape of the blank pattern in the photomask.

Fig. 10B is a diagram showing an example of a photomask for explaining a relationship between the device pattern formed on the transferred object and the shape of the blank pattern in the photomask.

Fig. 10C is a diagram showing an example of a photomask for explaining a relationship between the device pattern formed on the transferred object and the shape of the blank pattern in the photomask.

Fig. 11A is a diagram showing an example of a black matrix for explaining a relationship between the device pattern formed on the transfer target and the shape of the blank pattern in the photomask.

Fig. 11B is a diagram showing an example of a photomask for explaining a relationship between the device pattern formed on the transferred object and the shape of the blank pattern in the photomask.

Fig. 12A is a diagram showing an example of a black matrix for explaining a relationship between the device pattern formed on the transfer target and the shape of the blank pattern in the photomask.

Fig. 12B is a diagram showing an example of a photomask for explaining a relationship between the device pattern formed on the transferred object and the shape of the blank pattern in the photomask.

Fig. 13A is a diagram showing an example of a black matrix for explaining a relationship between the device pattern formed on the transfer target and the shape of the blank pattern in the photomask.

Fig. 13B is a diagram showing an example of a photomask for explaining a relationship between the device pattern formed on the transferred object and the shape of the blank pattern in the photomask.

Fig. 14 is a sectional view for explaining the method of manufacturing the 1 st photomask according to the above embodiment.

Fig. 15 is a sectional view for explaining the method of manufacturing the 2 nd photomask according to the above embodiment.

Fig. 16A is a diagram showing a model of a photomask (binary mask) used in optical simulation (simulation) in the embodiment of the present invention.

Fig. 16B is a diagram showing a model of a photomask (halftone mask) used in optical simulation in the embodiment of the present invention.

Fig. 17A is a graph showing a simulation result of the comparative example.

Fig. 17B is a diagram showing a simulation result of the comparative example.

Fig. 17C is a graph showing the simulation result of the comparative example.

Fig. 18A is a diagram showing a simulation result of embodiment 1 of the present invention.

Fig. 18B is a diagram showing a simulation result of embodiment 1 of the present invention.

Fig. 19 is a graph showing a simulation result of embodiment 2 of the present invention.

Fig. 20A is a diagram showing a simulation result of embodiment 3 of the present invention.

Fig. 20B is a diagram showing a simulation result of embodiment 3 of the present invention.

Fig. 20C is a graph showing a simulation result of embodiment 3 of the present invention.

Fig. 21A is a diagram showing a simulation result of embodiment 4 of the present invention.

Fig. 21B is a diagram showing a simulation result of embodiment 4 of the present invention.

Fig. 21C is a graph showing a simulation result of embodiment 4 of the present invention.

Fig. 22A is a diagram showing a simulation result of embodiment 5 of the present invention.

Fig. 22B is a diagram showing a simulation result of embodiment 5 of the present invention.

Fig. 22C is a diagram showing a simulation result of embodiment 5 of the present invention.

Description of the reference symbols

10. 12, 14: a photomask; 10a, 12a, 14 a: a transparent substrate; 10b, 12b, 14 b: a light-shielding area; 10c, 12c, 14 c: 1 st blank pattern; 14 d: a2 nd blank pattern; 11 a: a transfer-receiving body; 11 b: 1 st device pattern; 11 c: a2 nd device pattern; 110: an exposure device; 111: a light source; 112: an elliptical mirror; 113: an integrator; 114: a collimating lens.

Detailed Description

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

Fig. 5 and 6 are schematic views showing an example of a photomask according to the present embodiment and a1 st device pattern transferred to a transfer target using the photomask.

The photomask 10 shown in fig. 5 has: a light shielding region 10b formed by providing a light shielding film on a transparent substrate 10a, and a1 st blank pattern 10c having a line width Wm. The light-shielding region 10b and the 1 st blank pattern 10c constitute a transfer pattern (e.g., a pixel pattern). The 1 st blank pattern 10c is a light-transmitting portion formed by exposing the surface of the transparent substrate 10 a.

On the other hand, the photomask 12 shown in fig. 6 includes: a light shielding region 12b composed of a light shielding film or a light shielding film and a semi-light transmitting film is provided on a transparent substrate 12a, and a1 st blank pattern 12c having a line width Wm is provided on the transparent substrate 12a only with the semi-light transmitting film. The light-shielding region 12b and the 1 st blank pattern 12c constitute a transfer pattern (e.g., a pixel pattern).

In the photomask 12 shown in fig. 6, a semi-light-transmitting film may be formed on the transparent substrate 12a, and a light-shielding film may be laminated on the semi-light-transmitting film to form a light-shielding region, or only a light-shielding film may be formed on the transparent substrate to form a light-shielding region.

The line width is a Critical Dimension (CD), and is a line width in the case of a line pattern, and a diameter (or a short diameter) in the case of a hole pattern.

The photomask 10(12) has a main surface whose one side is 300mm or more. One side corresponds to one side of the photomask 10(12) when the outer shape is a square, and corresponds to a short side of the photomask when the outer shape is a rectangle. The photomask according to the present embodiment has an effect of suppressing deterioration of transferability due to in-plane misalignment of the proximity gap caused by flexure or distortion due to a holding jig or the like for reducing the flexure, and therefore, a significant effect can be obtained in a large photomask having one side of 300mm or more. Further, a photomask having a square shape with one side of 600mm or more (generation 6) can obtain a greater effect.

The 1 st blank pattern 10c (12c) is disposed so as to be surrounded by the light-shielding region 10b (12 b). In other words, the 1 st blank pattern 10c (12c) is disposed in a state of being sandwiched from both sides by at least the light-shielding regions (10b) (12 b). For example, when the 1 st blank pattern 10c (12c) has a line shape with a predetermined width, the light shielding region is disposed adjacent to both sides of the line. When the 1 st blank pattern 10c (12c) is a hole pattern, a light shielding region is disposed so as to surround the hole pattern.

The 1 st device pattern 11b formed on the transferred body 11a of the color filter substrate or the like has a fine width (Wp < 10 μm). The 1 st device pattern 11b may be used as, for example, a Photo Spacer (PS) used as a Black Matrix (BM) for a color filter or a Black Stripe (BS). It is preferable that the line width Wp of the 1 st device pattern 11b specifically satisfies 2 μm ≦ Wp < 10 μm. In the case where the 1 st device pattern 11b is used as a black matrix or black stripe, it is preferable that the line width Wp satisfies 3 μm ≦ Wp < 8 μm, and more preferable that the line width Wp satisfies 4 μm ≦ Wp < 7 μm.

On the other hand, it is preferable that the line width Wm of the 1 st blank pattern 10c (12c) constituting the transfer pattern satisfies 1 ≦ (Wm-Wp)/2 ≦ 4(μm). Here, the line width Wm of the 1 st blank pattern 10c (12c) is offset on both sides with respect to the line width Wp of the 1 st device pattern 11 b. That is, when the bias is β, 1 ≦ β ≦ 4(μm) holds. In this way, the 1 st device pattern 11b having a width in which both sides are increased by the amount of β on one side with respect to the line width Wm of the 1 st blank pattern 10c on the photomask 10 is transferred onto the transfer target 11 a. More preferably, the line width Wm of the 1 st blank pattern 10c (12c) satisfies 1.2Wp ≦ Wm ≦ 3.0 Wp. More preferably, the line width Wm of the 1 st blank pattern 10c (12c) satisfies 1.4Wp ≦ Wm ≦ 3.0 Wp.

When the 1 st blank pattern 10c is formed of a light-transmitting portion in which the surface of the transparent substrate 10a is exposed, as in the photomask 10, the line width Wm of the 1 st blank pattern 10c is preferably 1.4Wp ≦ Wm ≦ 2.0 Wp.

On the other hand, when the 1 st blank pattern 12c is formed of a semi-transmissive portion formed by forming a semi-transmissive film on the transparent substrate 12a as in the photomask 12, the line width Wm of the 1 st blank pattern 12c preferably satisfies 1.2Wp ≦ Wm ≦ 2.6 Wp. More preferably, the line width Wm of the 1 st blank pattern 12c satisfies 1.0 μm ≦ (Wm-Wp)/2 ≦ 3.0 μm, that is, 1.0 μm ≦ β ≦ 3.0 μm.

In the photomask 12, it is preferable that the semi-transmissive film is formed not only in a portion corresponding to the 1 st blank pattern 12c but also in a light-shielding region portion. That is, in the light-shielding region, it is preferable to adopt a structure in which a light-shielding film and a semi-light-transmissive film are laminated. This is because, when the patterned light-shielding film and the patterned semi-light-transmitting film are formed on the transparent substrate 12a, etching processes for the respective films are required, and it is not easy to sufficiently obtain the alignment accuracy.

However, for example, in a region where fine patterns such as pixel patterns do not exist (for example, a peripheral region of the photomask, see fig. 8), a light-transmitting portion exposed on the surface of the transparent substrate may be used, and in this case, the semi-light-transmitting film after film formation may be removed. Alternatively, the translucent film is not formed in such a region, and the transparent substrate 12a may be exposed. This is because the alignment (alignment) accuracy of patterning is not high the more such a region is within the pixel pattern.

In the photomask 12, the exposure light transmittance T of the semi-transparent film is preferably 20% to 60%. Further, the exposure light transmittance T of the semi-light transmissive film is more preferably 30% to 55%, and still more preferably 30% to 50%. This is because, when the exposure light transmittance T of the semi-transmissive film becomes excessively high, the film thickness of the semi-transmissive film becomes small, and in this case, a slight variation in the film thickness of the semi-transmissive film tends to cause a relatively large variation in the transmittance value. On the other hand, this is because, when the transmittance of the semi-transmissive film is too small, there is a risk that the amount of light transmitting the fine 1 st blank pattern 12c is insufficient.

The exposure light transmittance T of the semi-transparent film indicates the transmittance of the semi-transparent portion in which the semi-transparent film is formed on the transparent substrate 12a when the exposure light transmittance of the transparent substrate 12a is set to 100%. However, it is assumed that the semi-transmissive portion has a sufficient width as it is less affected by the adjacent pattern.

The exposure light transmittance T is a transmittance for a representative wavelength in a wavelength region including i-line to g-line serving as exposure light, and preferably, is a transmittance for all wavelengths of i-line, h-line, and g-line.

The photomask may be provided with a transfer pattern having a2 nd blank pattern with a line width Wn (Wn > Wm). Fig. 7 is a schematic diagram showing an example of a photomask having a2 nd blank pattern and a transferred object to which a2 nd device pattern is transferred using the photomask.

The photomask 14 shown in fig. 7 has: a light-shielding region 14b in which a light-shielding film or a light-shielding film and a semi-light-transmitting film are laminated, a1 st blank pattern 14c having a line width Wm, and a2 nd blank pattern 14d having a line width Wn are provided on a transparent substrate 14a made of quartz or the like. The light-shielding region 14b, the 1 st blank pattern 14c, and the 2 nd blank pattern 14d constitute a transfer pattern (e.g., a pixel pattern). The 1 st blank pattern 14c is formed of a semi-transmissive portion in which a semi-transmissive film is formed on the transparent substrate 14 a. The 2 nd blank pattern 14d is formed of a light-transmitting portion exposed from the surface of the transparent substrate 14 a.

The 2 nd blank pattern 14d in the photomask 14 is used to form the 2 nd device pattern 11c of the line width Wq on the transferred body 11 a. Preferably, the line width Wn of the 2 nd space pattern 14d is 8 μm or more and 10 μm or more. That is, the line width of the 2 nd blank pattern 14d is larger than the line width of the 1 st blank pattern 14c, and the transmitted light amount obtained by the translucent portion can be prioritized over the advantage (merit) of using the finer translucent portion described later.

Preferably, the transfer pattern in the photomask 10(12, 14) has a plurality of 1 st blank patterns 10c (12c, 14c) formed in a linear shape with a line width Wm, and a light shielding region having a width of 3 × Wm or more is interposed between the 1 st blank patterns 10c (12c, 14c) adjacent to each other in the width square.

As a result of interference between diffracted light generated at the edges of the slits, which are blank patterns, and light generated thereby, a light intensity distribution, which will be described later, is formed on the transfer target 11 a. Preferably, the light intensity distribution is a light intensity curve having a single peak in the center as described below (see fig. 17A, B, C to 22A, B, C). More preferably, the light intensity distribution has a single peak in the center, and a bell-shaped peak that monotonically increases or decreases on both sides of the peak, as in a gaussian distribution. This is achieved by appropriate selection of the design of the pattern for transfer (blank pattern line width, transmittance), and exposure conditions (illuminance, collimation angle).

This means that diffracted light caused by the diffraction action of light generated at both edges of the 1 st blank pattern 10c (12c, 14c), respectively, generates complex interference according to the width of the 1 st blank pattern 10c (12c, 14c), and as a result, the combined light intensity distribution forms a single peak. Preferably, the light intensity distribution formed on the transferred body 11a forms a single peak in a region of ± Wp/2 with respect to the center in the width direction. And, there may be side peaks (sidepeaks) outside the above region.

When the interval between the adjacent 1 st blank patterns 10c (12c, 14c) is small, if the adjacent 1 st blank patterns 10c (12c, 14c) interfere with each other by transmitted light, the shape of the light intensity distribution formed on the object 11a changes, and becomes complicated. As a result, the light intensity distribution does not necessarily show a single peak, and it is difficult to form a photosensitive material film pattern having a good resolution on the transfer target 11 a.

The transfer pattern in the photomask 10(12, 14) may be used for black matrix or black stripe fabrication.

Fig. 8 is a diagram showing an example of a black matrix manufactured using the photomask 10(12) according to the present embodiment. Fig. 8 shows a black matrix pattern panorama of 1 panel (panel). The black matrix 20 shown in fig. 8 is composed of a pixel pattern region 20a and a peripheral region 20 b. The pattern width of the peripheral region 20b is larger than the pattern width of the pixel pattern region, but the size ratio of other patterns, the area of the pixel pattern, and the arrangement position are appropriately changed depending on the device to be obtained.

Fig. 9A and 9B are views showing a part of a pixel portion of a photomask. Fig. 9A shows a photomask for forming the pixel pattern region 20a of the black matrix 20 shown in fig. 8. Here, the spacing interval isLight-shielding regions having a square shape are arranged in a matrix (matrix) and a blank pattern is formed between adjacent light-shielding regions. However, the light-shielding regions need not necessarily be square, and may be formed by regularly arranging light-shielding regions having a predetermined shape different from this. The photomask shown in fig. 9A has: light-shielding portion 21a and linear 1 st blank pattern 21b having line width Wm₁And the 1 st blank pattern 21b₁Line-shaped 2 nd blank pattern 21b having intersecting line width Wn (Wn > Wm)₂。

On the other hand, fig. 9B shows a striped photomask for forming black stripes. The photomask shown in fig. 9B has a light-shielding portion 21a and a linear 1 st blank pattern 21c having a line width Wm.

Fig. 10A, 10B, 10C to 13A, 13B are diagrams for explaining the relationship between the shapes of the device pattern formed on the transferred body and the blank pattern in the photomask. In these figures, the peripheral region of the photomask is not shown, and only the pixel pattern region is shown.

Fig. 10A shows a black matrix configured by the device patterns 22 in a line shape extending in the Y direction. To form the device pattern shown in fig. 10A, the photomask has a1 st blank pattern with a line width Wm in a line shape extending in the Y direction. The photomask shown in fig. 10B has a light-shielding portion 23a and a1 st blank pattern 23B composed of a light-transmitting portion. The photomask shown in fig. 10C has a light-shielding portion 23a and a1 st blank pattern 23C composed of a semi-light-transmitting portion.

Fig. 11A shows a black matrix including linear device patterns 24 extending in the X direction and the Y direction perpendicular to each other. In order to form the device pattern shown in fig. 11A, the photomask shown in fig. 11B has a linear 1 st blank pattern 24B having a line width Wm extending in the X direction and the Y direction, respectively. The photomask shown in fig. 11B has a light-shielding portion 24a and a1 st blank pattern 24B in a lattice shape formed of a semi-light-transmitting portion.

Fig. 12A shows a black matrix including a linear device pattern 25a having a line width Wp extending in the Y direction and a linear device pattern 25b having a line width Wq extending in the X direction (Wq > Wp). In order to form the device pattern shown in fig. 12A, the photomask shown in fig. 12B has a linear 1 st blank pattern 26B having a line width Wm extending in the Y direction and a linear 2 nd blank pattern 26c having a line width Wn extending in the X direction (Wn > Wm). The photomask shown in fig. 12B has a light-shielding portion 26a, and a1 st blank pattern 26B and a2 nd blank pattern 26c each formed of a semi-light-transmitting portion.

Preferably, the line width Wn of the 2 nd blank pattern 26c is 8 μm to Wn, and further 10 μm to Wn. The line width Wn of the 2 nd space pattern 26c is not limited to an upper limit, but may be configured to satisfy 8 μm ≦ Wn ≦ 30 μm, for example, in the case of using a cross line as shown in fig. 12B. Also, it is preferable that the relationship between the line width Wn of the 2 nd space pattern 26c and the line width Wq of the device pattern 25b satisfies 1.0 ≦ Wn/Wq ≦ 1.5, and more preferably satisfies 1.0 ≦ Wn/Wq ≦ 1.2.

Fig. 13A shows a black matrix including a linear device pattern 27a having a line width Wp extending in the Y direction and a linear device pattern 27b having a line width Wq extending in the X direction (Wq > Wp). In order to form the device pattern shown in fig. 13A, the photomask shown in fig. 13B has a linear 1 st blank pattern 28B having a line width Wm extending in the Y direction and a linear 2 nd blank pattern 28c having a line width Wn extending in the X direction (Wn > Wm). The photomask shown in fig. 13B includes a light-shielding portion 28a, a1 st blank pattern 28B formed of a semi-transmissive portion, and a2 nd blank pattern 28c formed of a transmissive portion.

Next, a method for manufacturing a photomask according to the present embodiment will be described.

Fig. 14 is a diagram for explaining the method of manufacturing the 1 st photomask according to the present embodiment.

First, as shown in fig. 14(a), photomask blank 30 is prepared in which light-shielding film 32 and resist film 33 are formed as optical films in this order on transparent substrate 31.

As the transparent substrate 31, a substrate transparent to exposure light, such as synthetic quartz, soda-lime glass (soda-lime glass), or alkali-free glass, can be used.

As the light-shielding film 32, chromium or a compound thereof can be used. For example, the light-shielding film 32 may be a chromium nitride film, a chromium carbide oxide film, a chromium oxynitride film, or a laminated film thereof.

Alternatively, as the light shielding film 32, a metal silicide may be used. For example, as the light shielding film 32, molybdenum silicide, tantalum silicide, titanium silicide, tungsten silicide, or an oxide, nitride, or oxynitride thereof can be used. The molybdenum silicide film used for the light shielding film 32 may be, for example, a MoxSiy film, a MoSiO film, a MoSiN film, a MoSiON film, or the like.

Next, as shown in fig. 14(b), the photomask blank 30 is drawn with a laser beam or an electron beam using a drawing apparatus, and the resist film 33 is exposed. The drawing data is used to form a light shielding portion.

Next, as shown in fig. 14(c), a developing solution is supplied to the resist film 33 to develop the resist film, thereby forming a resist pattern 33a covering a region to be formed of the light-shielding portion.

Next, as shown in fig. 14(d), the light shielding film 32 is etched using the resist pattern 33a as a mask, thereby forming a light shielding film pattern 32 a. Wet etching using a known etchant (etchant) can be applied to the etching of the light-shielding film 32. For example, if the light-shielding film 32 contains chromium or a compound thereof, an etchant for chromium (e.g., cerium ammonium nitrate, perchloric acid, and the like) may be used. If the light shielding film 32 contains silicide, a fluorine-based etchant can be used.

Next, as shown in fig. 14(e), after the resist pattern 33a is stripped, a semi-light-transmitting film 34 is formed on the entire surface of the transparent substrate 31 on which the light-shielding film pattern 32a is formed. The semi-light transmissive film 34 is formed in an appropriate film thickness by determining a desired transmittance and a phase shift amount (if necessary).

As the semi-light-transmitting film 34, a film using a chromium compound or a metal silicide as a raw material can be used. Examples of the chromium compound film used as the semi-light-transmitting film 34 include a chromium nitride film, a chromium carbide oxide film, a chromium oxide film, and a chromium oxynitride film.

As the metal silicide film used as the semi-light-transmitting film 34, a molybdenum silicide film, a tantalum silicide film, a titanium silicide film, a tungsten silicide film, or an oxide film, a nitride film, an oxynitride film, or the like thereof is given. The molybdenum silicide film used for the semi-light-transmitting film 34 may be, for example, a MoxSiy film, a MoSiO film, a MoSiN film, a MoSiON film, or the like.

According to the method for manufacturing a photomask, when the etching selectivity of the semi-light transmissive film 34 and the light transmissive film 32 is required, it is preferable to use a combination of a chromium-based film and a silicide-based film.

In the step shown in fig. 14(e), the transfer pattern of the photomask shown in fig. 10B, 10C, and 11B can be formed. That is, a photomask having the 1 st blank pattern 23b composed of a light transmitting portion having a line width Wm (1 ≦ Wm-Wp)/2 ≦ 4(μm)) or the 1 st blank pattern 23c (24b) composed of a semi-light transmitting portion having a line width Wm (1 ≦ Wm-Wp)/2 ≦ 4(μm)) for forming the device pattern 22(24) having Wp (Wp < 10 μm) on the transfer target can be manufactured by the above-described steps.

On the other hand, as in the transfer patterns of the photomask shown in fig. 12B and 13B, when the transfer pattern has a blank pattern with a line width Wn (Wn > Wm), the following steps are further performed.

As shown in fig. 14(f), a resist film 35 is formed on the entire surface of the photomask blank having the light-shielding film pattern 32a and the exposed semi-transmissive film 34. Then, the photomask blank 30a on which the resist film 35 is formed is subjected to drawing with a laser beam or an electron beam using a drawing apparatus, and the resist film 33 is exposed. The drawing data is used for forming a light-transmitting portion.

Next, as shown in fig. 14(g), a developing solution is supplied to the resist film 35 to develop the resist film, thereby forming a resist pattern 35a covering the light transmitting portion except for the region to be formed.

Next, as shown in fig. 14(h), the semi-transparent film 34 is etched using the resist pattern 35a as a mask, thereby forming a semi-transparent film pattern 34 a.

Finally, as shown in fig. 14(i), by peeling the resist pattern 35a, a photomask having a blank pattern with a line width Wn (Wn > Wm) formed by a light transmitting portion in addition to the blank pattern with a line width Wm can be manufactured.

The method of manufacturing the 1 st photomask shown in fig. 14 is an example of using a material having an etching selectivity between the semi-transmissive film 34 and the light-shielding film 32. However, even when there is no etching selectivity between the semi-transmissive film 34 and the light-shielding film 32, that is, even when the etchant for one of the semi-transmissive film 34 and the light-shielding film 32 has low resistance to the other, the method for manufacturing the 1 st photomask can be applied. In this case, it is necessary to consider the following: the pattern size may be affected by the alignment deviation in the 2-pass drawing process.

In addition, the transmittance of the semi-transmissive film 34 preferably satisfies 20% to 60%. Further, for example, as in the photomask shown in fig. 13B, when the transfer pattern includes a light-shielding portion, a semi-transmissive portion, and a transmissive portion, the transmissive portion and the semi-transmissive portion may be adjacent to each other. In this case, depending on the semi-transmissive film 34 selected, there is a possibility that: at the boundary with the light-transmitting portion, interference due to a phase difference of the transmitted light occurs, and an undesired dark portion is formed. Therefore, it is preferable to select the material and the film thickness of the semi-transmissive film 34 so that the phase difference of the transmitted light is 90 degrees or less, more preferably 60 degrees or less, between the adjacent light-transmissive portion and the semi-transmissive portion.

Next, a method for manufacturing a photomask, which is different from the method for manufacturing the above-described 1 st photomask, will be described. Fig. 15 is a diagram illustrating a method for manufacturing the 2 nd photomask according to the present embodiment.

First, as shown in fig. 15(a), a photomask blank 40 in which a semi-light transmissive film 42, a light shielding film 43, and a resist film 44 are formed on a transparent substrate 41 in this order is prepared. As described above, the method for manufacturing the 2 nd photomask is different from the method for manufacturing the 1 st photomask in that the semi-transmissive film 42 is formed on the transparent substrate 41.

Next, as shown in fig. 15(b), the photomask blank 40 is drawn with a laser beam or an electron beam using a drawing apparatus, and the resist film 44 is exposed. The drawing data is used to form a light shielding portion.

Next, as shown in fig. 15(c), a developing solution is supplied to the resist film 44 to develop the resist film, thereby forming a resist pattern 44a covering a region to be formed of the light-shielding portion.

Next, as shown in fig. 15(d), the light shielding film 43 is etched using the resist pattern 44a as a mask, thereby forming a light shielding film pattern 43 a.

Next, as shown in fig. 15(e), the resist pattern 44a is peeled off.

When the transfer pattern has a blank pattern with a line width Wn (Wn > Wm), the following steps are performed.

As shown in fig. 15(f), a resist film 45 is formed on the entire surface of the photomask blank having the semi-transmissive film 42 and the light-shielding film pattern 43 a. Then, the photomask blank 40a on which the resist film 45 is formed is subjected to drawing with a laser beam or an electron beam using a drawing apparatus, and the resist film 45 is exposed. The drawing data is used for forming a light-transmitting portion.

Next, as shown in fig. 15(g), a developing solution is supplied to the resist film 45 to develop the resist film, thereby forming a resist pattern 45a covering the light transmitting portion except for the region to be formed.

Next, as shown in fig. 15(h), the semi-light transmissive film 42 is etched using the resist pattern 45a as a mask, thereby forming a semi-light transmissive film pattern 42 a.

Finally, as shown in fig. 15(i), by peeling the resist pattern 45a, a photomask having a2 nd blank pattern with a line width Wn (Wn > Wm) formed of a light transmitting portion in addition to the 1 st blank pattern with a line width Wm can be manufactured.

In the method of manufacturing the 2 nd photomask shown in fig. 15, a material having an etching selectivity between the semi-light transmissive film 42 and the light shielding film 43 is used. The thickness of the semi-transmissive film 42 needs to be determined in advance for the transmittance to be obtained.

Next, a pattern transfer method using the photomask according to the present embodiment will be described.

The pattern transfer method according to the present embodiment forms the 1 st device pattern having the line width Wp on the object to be transferred by exposing the negative photosensitive material film formed on the object to be transferred using the proximity exposure apparatus using the photomask having the transfer pattern. For example, a black matrix in a display device may be manufactured using such a pattern transfer method.

In this case, a pattern transfer method for forming a device pattern having a line width Wp on a transfer target using a photomask blank having a transfer pattern with a main surface of 300mm or more on one side, the transfer pattern including: in the pattern transfer method, a pattern can be transferred by a transfer method in which the pattern is transferred by applying an appropriate exposure condition so that the relationship between the line width Wp of the device pattern and the line width Wm of the 1 st blank pattern satisfies the following expressions (1) and (2).

Wp＜10μm…(1)

1≦(Wm－Wp)/2≦4(μm)…(2)

Preferably, the photomask according to the present embodiment is used for proximity exposure in which the proximity gap is in the range of 10 to 200 μm. More preferably, the proximity gap is in the range of 30 to 150 μm, and still more preferably in the range of 60 to 150 μm. Further, it is preferable that the proximity gap is within the above range at any position in the plane even when there is an in-plane variation in which the proximity gap differs depending on the in-plane position of the transferred object.

Here, the effect of the present invention becomes remarkable when the distribution of the proximity gap in the plane, that is, the difference between the maximum value and the minimum value of the proximity gap is in the range of 30 μm to 100 μm. That is, the photomask according to the present embodiment is useful in a system in which the distribution of the proximity gap in the plane varies.

In designing the transfer pattern of the photomask according to the present embodiment, it is preferable that when the device pattern is transferred onto the object to be transferred, the light intensity variation of the exposure light caused by the light intensity variation is suppressed even in the presence of the proximity gap, and the in-plane CD distribution is set to the target CD ± 10% or the CD variation is set to 1 μm or less.

For example, referring to fig. 20A, 20B, and 20C, when the proximity gap varies from 70 μm to 130 μm and the distribution of the proximity gap is 60 μm (see fig. 20A), the CD variation is suppressed to 0.9 μm or less (see fig. 20B). In fig. 21B, the CD variation is 0.8 μm or less, and in fig. 22B, the CD variation is 0.7 μm or less (among others, CD due to light intensity distribution).

(examples)

In order to confirm the transferability of the photomask according to the embodiment of the present invention, optical simulation was performed using the model shown in fig. 16.

Fig. 16A shows a photomask (binary mask) 50 having a light-transmitting portion. The photomask 50 has: a light shielding portion 50a and a blank pattern 50b formed of a light transmitting portion having a line width Wm. Also, fig. 16B shows a photomask (halftone mask) 51 having a translucent portion. The photomask 51 has: a light-shielding portion 51a and a blank pattern 51b composed of a semi-transmissive portion having a line width Wm.

Comparative example

In the photomask 50 shown in fig. 16A, when the line width Wp of the device pattern to be formed on the transferred object is 5 μm and the line width Wm of the blank pattern 50b in the photomask 50 is 5 μm, that is, when the offset β is 0, the proximity gap is varied to obtain the CD variation and the peak value of the light intensity. Here, the case of approaching the gap of 100 μm was used as a reference, and the case of obtaining the target CD at this value was examined.

Fig. 17A is a graph showing a light intensity distribution formed on a transferred body. In fig. 17A, the horizontal axis represents a position on the mask, and the vertical axis represents light intensity. The proximity gap varies between 70 μm and 130 μm every 5 μm. In fig. 17A, a graph 170a shows a graph close to the gap of 70 μm, a graph 170b shows a graph close to the gap of 130 μm, and a graph 170c shows a graph close to the gap of 100 μm.

Fig. 17B is a graph showing the relationship between the proximity gap and the CD of the formed pattern. In fig. 17B, the horizontal axis represents the proximity gap, and the vertical axis represents CD [ μm ]. Fig. 17C is a graph showing a relationship between the light intensity near the gap and the peak. In fig. 17C, the horizontal axis represents the proximity gap, and the vertical axis represents the light intensity.

As shown in FIG. 17B, when the proximity gap varies from 70 μm to 130 μm, that is, while varying by 60 μm, CD variation of about 2.3 μm occurs. As shown in fig. 17C, when the proximity gap varies from 70 μm to 130 μm, that is, in the 60 μm variation, a light intensity variation having a peak value of 0.35 unit (relative value) occurs.

(example 1)

In the photomask 50 shown in fig. 16A, the same simulation was performed, as in the comparative example, with the line widths Wp of the device patterns to be formed on the transferred object set to 5 μm, and with the line widths Wm of the blank patterns 50b in the photomask 50 set to 6 μm and 7 μm. That is, the values of the offsets β are 0.5 μm and 1.0 μm, respectively, and Wm/Wp is 1.2 and 1.4, respectively.

Fig. 18A and 18B show simulation results. Fig. 18A is a graph showing the relationship between the proximity gap and the CD. In fig. 18A, the horizontal axis represents the proximity gap, and the vertical axis represents CD [ μm ]. Fig. 18B is a graph showing a relationship between the light intensity near the gap and the peak. In fig. 18B, the horizontal axis represents the proximity gap, and the vertical axis represents the light intensity.

In fig. 18A and 18B, a graph 180a shows a graph in which the line width Wm of the blank pattern 50B is 5 μm, a graph 180B shows a graph in which the line width Wm of the blank pattern 50B is 6 μm, and a graph 180c shows a graph in which the line width Wm of the blank pattern 50B is 7 μm.

As shown in fig. 18A, in the graphs 180b and 180c, CD variation of about 1 μm occurs in both. As shown in fig. 18B, the larger the value of the offset β, the larger the light intensity of the peak in the same proximity gap. In particular, in the graph 180c in which the line width Wm is set to 7 μm, the light intensity at the peak is greatly increased as compared with the comparative example shown in the graph 180 a. The increase in light intensity is advantageous in sufficiently generating the crosslinking reaction of the negative photosensitive material.

(example 2)

The difference from the photomask 50 in the case of using the photomask 51 shown in fig. 16B was examined.

Fig. 19 is a graph showing a light intensity distribution formed on a transferred body. In fig. 19, the horizontal axis represents a position on the mask, and the vertical axis represents light intensity. In fig. 19, a graph 190a shows a comparative example. The graph 190B shows a graph in the case where the line width Wp of the device pattern to be formed on the transferred object is 5 μm, the line width Wm of the blank pattern 51B in the photomask 51 is 8 μm, and the transmittance of the semi-transparent film constituting the blank pattern 51B is 55% in the photomask 51 shown in fig. 16B. In this way, the peak intensities of the light intensity distributions in the graph 190a and the graph 190b representing the comparative examples are made to coincide to the same extent.

As shown in fig. 19, in the present embodiment 2 (graph 190b) using the halftone mask, the peak shape is sharper (sharp) compared to the binary mask (graph 190a) every time the same peak intensity is obtained. That is, according to embodiment 2, not only a finer pattern can be formed, but also the inclination angle of the light intensity is large and close to vertical. This means that the cross-sectional shape of the edge portion of the obtained resist pattern is nearly vertical when actually used for transfer, and this shows an excellent effect of increasing the processing accuracy in the subsequent step. This can contribute to improvement in stability of performance and yield in intermediate products such as color filters and final products such as display devices.

(example 3)

From the results of example 2, in the photomask 51 shown in fig. 16B, when the line width Wp of the device pattern to be formed on the transferred object was set to 5 μm, the line width Wm of the blank pattern 51B in the photomask 51 was set to 7 μm, and the transmittance of the semi-transparent film was set to 55%, the proximity gap was varied, and the CD variation and the peak value of the light intensity were determined. Here, the case of approaching the gap of 100 μm was used as a reference, and the case of obtaining the target CD at this value was examined.

Fig. 20A is a graph showing a light intensity distribution formed on a transferred body. In fig. 20A, the horizontal axis represents a position on the mask, and the vertical axis represents light intensity. The proximity gap varies between 70 μm and 130 μm every 5 μm. In fig. 20A, a graph 200A shows a graph approaching the gap 70 μm, a graph 200b shows a graph approaching the gap 130 μm, and a graph 200c shows a graph approaching the gap 100 μm.

Fig. 20B is a graph showing the relationship between the proximity gap and the CD of the formed pattern. In fig. 20B, the horizontal axis represents the proximity gap, and the vertical axis represents CD [ μm ]. Fig. 20C is a graph showing a relationship between the light intensity near the gap and the peak. In fig. 20C, the horizontal axis represents the proximity gap, and the vertical axis represents the light intensity.

As shown in FIG. 20B, when the proximity gap was varied from 70 μm to 130 μm, i.e., during a variation of 60 μm, the CD was varied by less than 1 μm. As shown in fig. 20C, when the proximity gap varies from 70 μm to 130 μm, that is, in a variation of 60 μm, a light intensity variation having a peak value of 0.25 unit (relative value) occurs.

(example 4)

The same simulation as in example 3 was performed assuming that the line width Wm of the blank pattern 51b in the photomask 51 was 8 μm.

Fig. 21A is a graph showing a light intensity distribution formed on a transferred body. In fig. 21A, the horizontal axis represents a position on the mask, and the vertical axis represents light intensity. The proximity gap varies between 70 μm and 130 μm every 5 μm. In fig. 21A, graph 210a shows a graph near the gap of 70 μm, graph 210b shows a graph near the gap of 130 μm, and graph 210c shows a graph near the gap of 100 μm.

Fig. 21B is a graph showing the relationship between the proximity gap and the CD of the formed pattern. In fig. 21B, the horizontal axis represents the proximity gap, and the vertical axis represents CD [ μm ]. Fig. 21C is a graph showing a relationship between the light intensity near the gap and the peak. In fig. 21C, the horizontal axis represents the proximity gap, and the vertical axis represents the light intensity.

As shown in FIG. 21B, when the proximity gap varies from 70 μm to 130 μm, i.e., during a variation of 60 μm, the CD variation is smaller and less than 0.8 μm. Also, as shown in fig. 21C, the light intensity of the peak increases as compared with example 3.

(example 5)

The same simulation as in example 3 was performed assuming that the line width Wm of the blank pattern 51b in the photomask 51 was 9 μm.

Fig. 22A is a graph showing a light intensity distribution formed on a transferred body. In fig. 22A, the horizontal axis represents a position on the mask, and the vertical axis represents light intensity. The proximity gap varies between 70 μm and 130 μm every 5 μm. In fig. 22A, a graph 220a shows a graph approaching the gap 70 μm, a graph 220b shows a graph approaching the gap 130 μm, and a graph 220c shows a graph approaching the gap 100 μm.

Fig. 22B is a graph showing the relationship between the proximity gap and the CD of the formed pattern. In fig. 22B, the horizontal axis represents the proximity gap, and the vertical axis represents CD [ μm ]. Fig. 22C is a graph showing a relationship between the light intensity near the gap and the peak. In fig. 22C, the horizontal axis represents the proximity gap, and the vertical axis represents the light intensity.

As shown in FIG. 22B, when the proximity gap varies from 70 μm to 130 μm, i.e., during a variation of 60 μm, the CD variation is smaller and less than 0.7 μm. Also, as shown in fig. 22C, the light intensity of the peak increases as compared with example 4.

As is clear from the above, the amount of light reaching the object to be transferred can be adjusted by making the blank pattern of the photomask, which is necessary for forming a pattern having a fine width on the object to be transferred, have a larger line width than that of the blank pattern. And it is known that by adjusting the offset amount (β), more preferably, the offset ratio Wm/Wp, CD variations of the transfer pattern with respect to variations close to the gap can be effectively suppressed. This is of great significance in particular in mass production.

In addition, this effect is caused by: a light intensity variation caused by approaching an exposure gap is reduced by using a pattern having a line width larger than a target line width formed on a transferred body as a blank pattern of a photomask. Further, by using a semi-transparent film on the blank pattern of the photomask, exposure is performed by appropriately adjusting the intensity of transmitted light, and the effect of suppressing the line width variation due to the exposure gap is obtained.

According to the present invention, the pattern having the fine width can be formed without depending on a technique such as a so-called projection exposure apparatus for semiconductor manufacturing or a phase shift mask.

The present invention is not limited to the above-described embodiments, and can be implemented by being variously modified. In the above-described embodiments, the size, shape, and the like shown in the drawings are not limited thereto, and can be appropriately modified within a range in which the effects of the present invention are exhibited. Further, the present invention can be implemented with appropriate modifications without departing from the intended scope of the present invention.

For example, the present invention is not limited to the black matrix and the black stripe, and can be applied to a Photo Spacer (PS) of a liquid crystal display device, and the like. In this case, the blank pattern in the above embodiment is a different shape such as a hole pattern, but does not hinder the effect of the present invention.