JP2003337328A - Photomask, and method for manufacturing liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photomask capable of efficiently obtaining a directional reflection plate having a desired shape, and to provide a method for manufacturing a liquid crystal display device using the photomask. <P>SOLUTION: The photomask 100 is provided with a plurality of aperture parts 112, the aperture parts 112 are constituted asymmetrically in the longitudinal direction and the surface areas of the aperture parts on the upper side from the center in the longitudinal direction are made smaller than the surface areas of the aperture parts on the lower side. By using the photomask 100 having such aperture parts, the side having large surface areas of the aperture parts in individual aperture parts 112 has a relatively large quantity of exposure an the side having small surface areas of the aperture parts has a relatively small quantity of exposure and distribution of the quantity of exposure in the longitudinal direction can be generated. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photomask and a method for manufacturing a liquid crystal display device, and more particularly, to a photomask capable of effectively forming a directional surface with respect to an object to be exposed, and the same. The present invention relates to a method for manufacturing a liquid crystal display device using a photomask.

[0002]

2. Description of the Related Art Reflective liquid crystal display devices have low power consumption because they do not have a light source such as a backlight, and have been widely used in various portable electronic devices and display units attached to devices. As this type of liquid crystal display device, one having a structure in which a reflective film and a liquid crystal layer are sandwiched between substrates is adopted, and light incident from one substrate side is reflected by the reflective film after passing through the liquid crystal layer. Then, the light again passes through the liquid crystal layer as reflected light and is used for display.

[0003]

Since such a reflective liquid crystal display device uses external light such as sunlight or illumination light to perform display, it is used in places such as indoors where the amount of external light is limited. Then, the visibility of the display may decrease. Therefore, a technique has been proposed in which a large number of concavities and convexities are formed on a reflective film and diffused reflected light to obtain a bright display with a wide viewing angle. Furthermore, the reflected light is used more effectively in the limited light quantity,
From the viewpoint of obtaining a display that is bright to the eyes of the user,
An unevenness having an asymmetric cross-sectional shape is formed on the reflection film, that is, unevenness having a surface with a gentle slope and a surface with a steep slope is formed, and anisotropy (hereinafter referred to as directivity) in light diffusion is provided. A technique for matching the direction of reflected light with the direction of the user's eyes by holding the so-called directional reflector has been proposed.

As a method for obtaining a directional reflector, a photosensitive resin is applied on a base material, and then exposed and developed using a photomask having vertically asymmetric openings.
Obtaining a scattering resin layer having a gentle slope and a steep slope in the vertical direction,
There is a method of obtaining a directional reflector by forming a reflective film on the scattering resin layer. In such a method, the exposure is performed through the opening or the light shielding portion of the photomask, but since light may leak from the opening due to diffraction, the opening or the light shielding portion of the photomask in the scattering resin layer. In some cases, a pattern that is more bulged than the shape may be formed. Therefore, when the scattering resin layer having a desired pattern (that is, a pattern corresponding to the shape of the opening) cannot be obtained and, for example, the inclined surface is sagged, and the gentle slope or the steep surface having the desired shape or the desired inclination angle cannot be obtained. In some cases, the desired directivity may not be imparted to the reflective film.

The present invention has been made to solve the above problems, and a photomask which enables a directional reflector having a desired shape to be efficiently obtained, and a liquid crystal display using the photomask. An object is to provide a method for manufacturing a device.

[0006]

In order to achieve the above object, a photomask of the present invention is a photomask having an opening or a light shielding portion for exposing an object, the opening or the light shielding portion. Are asymmetrically formed in the longitudinal direction and have an angle of at least more than 180 degrees.

According to such a photomask, since the openings or the light shields are formed asymmetrically in the vertical direction, for example, a negative photosensitive resin (exposure target) exposed through the photomask is exposed. In this case, the distribution of the exposure amount is generated at least in the vertical direction, and by developing the exposed object, it is possible to form two or more inclined surfaces having different inclination angles in the vertical direction. Furthermore, since the photomask of the present invention is provided with an angle of at least more than 180 degrees, it is possible to prevent the inclined surface formed on the exposed object corresponding to the position of an angle of more than 180 degrees from spreading out. It will be suppressed. Ie 180
The corners that exceed the degree are the corners that are recessed inward, and the recessed positions play the role of spreading white, and when the object is exposed using the photomask, the corners that are recessed It is possible to prevent or suppress the occurrence of sagging on the inclined surface that may be formed on the exposure object, corresponding to the formation position of. Therefore, by exposing and developing the object to be exposed using the photomask of the present invention, two or more inclined surfaces having different inclination angles in the vertical direction are formed, and unintended spread (sag) is reduced. Resin layer (scattering resin layer)
Can be obtained. A directional reflective film can be obtained by forming a solid reflective film of Al or the like on such a resin layer, and such a reflective film exhibits excellent directivity. , It becomes possible to direct the reflected light in the intended direction. Also, the same effect can be obtained when a positive photosensitive resin is used, that is,
The resin layer will have a concave inclined surface.

The opening portion or the light shielding portion may be formed in a concave polygonal shape. By forming the openings or light-shielding parts in a polygonal shape, the amount of data when designing a photomask with an electronic computer is reduced, the processing speed is increased, and a variety of shapes of openings or light-shielding parts are designed. It becomes possible to do.

Further, a tapered acute-angled portion may be formed on one side of the opening in the vertical direction. In this case, in the object to be exposed, the exposure amount becomes relatively small at the position corresponding to the tapered acute angle portion,
By developing this, it becomes possible to surely form a gentle slope having a small inclination angle at a position corresponding to the acute angle portion.

Further, the opening or the light-shielding portion may be formed substantially symmetrically in the lateral direction, and at least two corners of at least 180 degrees may be provided substantially symmetrically in the lateral direction. In this case, the spread (drip) of the inclined surface in the object to be exposed is further unlikely to occur, and the directivity in the vertical direction is further enhanced. On the axis of symmetry,
In addition, by forming a tapered acute-angled portion on one side of the opening in the vertical direction, the effect of the present invention becomes more remarkable, and a resin layer having high directivity can be obtained.

Next, in order to solve the above-mentioned problems, a method of manufacturing a liquid crystal display device of the present invention comprises a step of forming a photosensitive resin layer directly on a substrate or through another member, and a formed photosensitive resin layer. A step of patterning the photosensitive resin layer into a predetermined shape by exposing the layer to light using the above-mentioned photomask, and forming a reflection film by directly or by opening another member on the patterned resin layer And a process.

By exposing the photosensitive resin layer thus formed on the base material using the photomask, a resin layer having two or more inclined surfaces having different inclination angles is formed as described above. By forming a reflective film on this, it becomes possible to manufacture a liquid crystal display device having a directional reflective film. In this case, since the photomask of the present invention is used, it is possible to obtain a resin layer having an intended directivity, and thus it is possible to provide the liquid crystal display device with a reflective directivity that matches the purpose.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [Photomask] An embodiment of the photomask of the present invention will be described below with reference to the drawings. FIG. 1 is a partially enlarged plan view of a photomask of the present invention, and FIG. 2 is an explanatory view showing an enlarged shape of an opening formed in the photomask of FIG.

The photomask 100 shown in FIG. 1 is a mask for providing an exposure surface of a predetermined pattern when performing exposure in a photolithography method or the like, and is a mask composed of a member having a low light-transmitting property. The main body 110 and a plurality of openings 112 provided in the mask main body 110 are provided. Specifically, the mask body 110
Has a structure in which a light-shielding film such as chrome is formed on a base material composed mainly of quartz, and the opening 112 is formed in a predetermined position of the mask main body 110 in a predetermined pattern. . In the present embodiment, a plurality of openings 112 having a shape as shown in FIG. 2 are formed, and each opening 112 is configured to include a portion that partially overlaps an adjacent opening.

The opening 112 is asymmetrical in the vertical direction (vertical direction in the drawing), and the opening area above the center 113 in the vertical direction is smaller than the opening area below the lower side 114. Then, the opening 112 has a concave corner 1.
It has a concave polygonal opening shape including 15 (angles exceeding 180 degrees), is a concave hexagon in the case of the present embodiment, and the upper side 113 from the center is configured to include a tapered acute angle. ing.

Further, the opening 112 is formed substantially symmetrically in the lateral direction (horizontal direction in the drawing), and is provided with the above-mentioned concave corner 115 at least substantially symmetrically in the lateral direction, and the above-mentioned symmetry axis 119 is provided on the symmetry axis 119. Is formed by forming a tapered acute angle portion. Photomask 100 having an opening having such a configuration
According to the above, in each of the openings 112, the exposure amount on the lower side 114 having a large opening area is relatively large, and the exposure amount on the upper side 113 having a small opening area is relatively small, that is, in the vertical direction. It is possible to give rise to a distribution of quantities. It should be noted that as shown in FIG.
It is also possible to form a concave pentagon, and in this case as well, the concave corner 125 is formed symmetrically with the axis of symmetry 119.
3 is provided with a tapered acute angle portion.

When photolithography is performed on a negative photosensitive resin layer using the photomask 100 having the above-mentioned structure, a resin layer 200 having a pattern as shown in FIG. 4 is obtained. You can That is, the light for exposure is applied to the photosensitive resin layer through the opening 112, but since the light is diffused on the way from the opening 112 to the photosensitive resin layer, the opening shape (see FIG. )
The photosensitive resin layer is exposed in a pattern wider than (indicated by a broken line in the figure), and the resin layer 200 after development is slightly wider than the opening shape of the opening 112. Shape pattern.

Further, the opening 112 of the photomask 100.
Are formed asymmetrically in the vertical direction, so that a distribution of the exposure amount occurs in the vertical direction in the negative photosensitive resin layer, and by developing this, the inclination angle in the vertical direction as shown in FIG. It is possible to form a plurality of inclined surfaces 210 and 220 having different shapes. Further, since the photomask 100 has the concave corner 115, the resin layer 20 to be patterned is formed.
0, the resin layer 2 at the position of the concave corner 115.
It is difficult for 00 to curve outward and spread.

At the position corresponding to the tapered acute angle portion on the upper side 113 in the figure, the exposure amount changes gently in the vertical direction, while on the lower side 114 in the figure, the exposure amount changes sharply in the vertical direction. Therefore, the inclined surface 210 becomes a gentle inclined surface 210 having a small inclination angle, and the inclined surface 220 becomes a steep inclined surface 220 having a large inclination angle. Note that the exposure amount becomes maximum near the center of gravity of the opening 112 of the photomask 100, and the layer thickness of the resin layer 200 becomes maximum at the position corresponding to the center G of gravity of the opening 112 (see FIG. 4A). Become.

As described above, the photomask 1 of this embodiment
00 is used to expose the negative photosensitive resin, and this is developed to develop the resin layer 20 having the predetermined pattern shown in FIG.
0 was obtained, and the cross-sectional shapes thereof were a gentle slope 210 and a slope 22
Will have 0 and. Further, in particular, since the upper side 113 of the opening 112 in the drawing is formed into a tapered acute angle shape, the gentle slope 210 corresponding to the tapered acute angle portion has a lower side 11 in the drawing.
The area is larger than the steep slope 220 corresponding to No. 4. Although the case where the negative type photosensitive resin is used has been described in the present embodiment, the same effect can be obtained also when the positive type photosensitive resin is used, that is, the concave shape of the resin layer is obtained. Will be formed. Further, although the case where a photomask having an opening having a desired shape is used is described in this embodiment mode, similar effects can be obtained also when a photomask having a light-blocking portion having a desired shape is used. It is possible, that is, when a negative photosensitive resin is used, a swelled inclined surface is formed in the resin layer.

[Manufacturing Method of Liquid Crystal Display Device] Next, an example of a manufacturing method of a liquid crystal display device using the photomask 100 of the above embodiment will be described. First, FIG.
As shown in (a), a negative photosensitive resin layer 150 is formed on a transparent substrate 2 such as glass or plastic, and exposure is performed from above using the photomask 100 shown in FIG. Then, the exposed photosensitive resin layer 150 is developed to obtain the resin layer 200 having the inclined surfaces 210 and 220 shown in FIG. 5B. Further, as shown in FIG. 5C, a reflective material such as Al is formed on the entire surface of the resin layer 200 so that the directional reflective film 26 is formed. The directional reflection film 26 is formed on the inclined surface 210 of the resin layer 200.
Based on the angle of (or 220), it is possible to direct the reflected light in the intended direction.

Then, a flattening film is formed on the directional reflection film 26,
While forming a transparent electrode and an alignment film, a color filter and a black matrix, an overcoat film, a transparent electrode and an alignment film are formed on different base materials, and these base materials are bonded together via a liquid crystal material and sealed. A liquid crystal panel is obtained by sealing with a material. Then, the obtained liquid crystal panel is equipped with a driving device or the like to obtain a liquid crystal display device.

[Liquid Crystal Display Device] Next, the structure of the liquid crystal display device manufactured by the manufacturing method of the above embodiment will be described with reference to the drawings. 6 is a plan view showing the overall configuration of the liquid crystal display device of the present embodiment, FIG. 7 is a view showing the display area of the liquid crystal display device, and a cross-sectional view taken along the line BB ′ of FIG. 6 ( It is sectional drawing which shows the state cut | disconnected in the horizontal direction.
The present embodiment is an example of a passive matrix type reflective color liquid crystal display device, and is an example in which a built-in reflector having the above directional reflector is formed on the inner surface side of a lower substrate. In all of the following drawings, in order to make the drawings easy to see, the film thicknesses, the dimensional ratios, and the like of the respective constituent elements are appropriately changed.

As shown in FIG. 6, the liquid crystal display device 1 of the present embodiment has a lower substrate 2 (similar to the base material 2 shown in FIG. 5) and an upper substrate 3 (the other one having a rectangular shape in plan view). And a substrate) are arranged to face each other with the sealing material 4 interposed therebetween. A part of the sealing material 4 is opened on one side (upper side in FIG. 6) of each of the substrates 2 and 3 to form a liquid crystal inlet 5, and a space surrounded by both the substrates 2 and 3 and the sealing material 4. Liquid crystal is sealed inside, and the liquid crystal injection port 5 is sealed by a sealing material 6. In the present embodiment, the outer dimension of the lower substrate 2 is larger than that of the upper substrate 3, and the edges of the upper substrate 3 and the lower substrate 2 are aligned on one side (the upper side in FIG. 6). The peripheral portion of the lower substrate 2 is arranged so as to protrude from the remaining three sides (lower side, right side, left side in FIG. 6). Then, the driving semiconductor element 7 for driving the electrodes of both the upper substrate 3 and the lower substrate 2 is mounted on the end portion on the lower side of the lower substrate 2. Note that reference numeral 8
Is a light shielding layer (peripheral parting) for shielding the periphery of the display area.

In the case of the present embodiment, as shown in FIG.
On the lower substrate 2, a plurality of segment electrodes 10 extending in the vertical direction in the figure are formed in stripes. On the other hand, on the upper substrate 3, a plurality of common electrodes 11 extending in the horizontal direction in the drawing so as to be orthogonal to the segment electrodes 10 are formed in stripes. In order to perform color display, the R, G and B dye layers of the color filter are connected to the segment electrodes 10 respectively.
Are arranged in correspondence with the direction of (vertical stripes / RGB are arranged vertically in the same color in stripes),
One pixel on the screen is composed of three pixels R, G, and B arranged in the horizontal direction. The “pixel” in this embodiment means the segment electrode 10 and the common electrode 11.
And are the overlapping areas when viewed two-dimensionally. The “display area” is an area in which a large number of pixels inside the light-shielding layer 8 are arranged in a matrix and actually contributes to the display.

Looking at the sectional structure, as shown in FIG. 7, a resin layer 200 made of a photosensitive resin is formed on the lower substrate 2, and the resin layer 200 has a large number of inclined surfaces 210 and 220. In this case, many inclined surfaces 210 and 220 are arranged in one pixel. Then, along the surface of the resin layer 200 having these inclined surfaces, a reflection layer (directional reflection layer) formed of a metal film having a high light reflectance such as aluminum or silver.
26 is formed, and a reflecting surface is formed along the inclined surface of the resin layer 200. The reflective layer 26 has a directivity of reflected light in the vertical direction of the display area, and for example, it is possible to direct light obliquely incident from above in the vertical direction in the direction perpendicular to the base material.

A flattening film 27 made of a resin film such as acryl or polyimide or an insulating film such as a silicon oxide film is formed on the reflective layer 26, and indium tin oxide (Indium Tin Oxide) is formed on the flattening film 27. Oxide, hereinafter abbreviated as ITO) segment electrodes 10 are formed in a stripe shape in a direction penetrating the paper surface, and an alignment film 20 made of, for example, polyimide whose surface is rubbed is formed on the segment electrodes 10. Has been done.

On the other hand, on the upper substrate 3 made of a transparent substrate such as glass or plastic, each of the dye layers 13r,
A color filter 13 composed of 13g and 13b is formed, and a resin overcoat film 21 is formed on the color filter 13 for flattening the step between the dye layers and protecting the surface of each dye layer at the same time. . further,
The common electrode 11 made of an ITO film is formed on the overcoat film 21 in a stripe shape in a direction parallel to the paper surface, and the alignment film 22 made of, for example, a rubbing-processed polyimide is formed on the common electrode 11. ing.

Between the upper substrate 3 and the lower substrate 2, STN (Su
A liquid crystal 23 such as a per Twisted Nematic liquid crystal is sandwiched. Further, for example, the black stripes 33 made of resin black or a metal such as chromium having a relatively low reflectance are formed in the R, G, and B dye layers 13r, 13g, and 13b.
It is provided so as to partition the space (boundary).

Since the liquid crystal display device 1 of the present embodiment is provided with the reflection film 26 having the reflection surface with a predetermined inclination angle, it becomes possible to direct the reflected light in a predetermined direction,
As a result, a bright reflective display can be obtained without depending on the lighting environment. Further, since the reflective film 26 of the present embodiment is formed by the method using the photomask 100 shown in the above-described embodiment, it becomes easier to give the intended directivity to the reflective film 26, and the reliability is further ensured. It is possible to provide a bright reflective display.

The technical scope of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, in the embodiment of the method for manufacturing a liquid crystal display device, an example in which the collective exposure is performed has been described, but the exposure may be performed in every predetermined step by a stepper or the like. Further, in the present embodiment, the reflection film 26 is formed directly on the formed resin layer 200, but a thin film resin layer is further formed on the resin layer 200, and the reflection film 26 is formed thereon. In this case, the surface of the reflective film 26 can be made smoother.

[0032]

As described above in detail, according to the photomask of the present invention, it becomes possible to form a resin layer having a gentle slope and a steep slope having an intended angle by exposure, and the resin layer is reflected. By forming the film, it becomes possible to obtain a reflective layer having a directivity more suited to the purpose.

[Brief description of drawings]

FIG. 1 is a plan view showing a schematic configuration of a photomask according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an opening shape of the photomask of FIG.

FIG. 3 is an explanatory diagram showing a modified example of the opening shape of the photomask.

4A and 4B are a plan view and a cross-sectional view showing a configuration of a resin layer when a negative photosensitive resin layer is exposed and developed using the photomask of FIG.

5A and 5B are explanatory views showing a manufacturing process of a liquid crystal display device using the photomask of FIG.

6 is a plan view showing an overall configuration of a liquid crystal display device obtained by a manufacturing method using the photomask of FIG.

7 is a view showing a display area of the liquid crystal display device and is a cross-sectional view taken along line BB ′ of FIG.

[Explanation of symbols]

1 Liquid crystal display 2 Lower substrate (base material) 26 Reflective layer 100 photo mask 112 opening 150 Photosensitive resin 200 resin layer

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Claims (6)

[Claims] 1. A photomask having an opening for exposing an object, wherein the opening or the light-shielding portion is formed asymmetrically in a vertical direction and has an angle of at least more than 180 degrees. Photo mask to be. 2. The photomask according to claim 1, wherein the opening portion or the light shielding portion is formed in a concave polygonal shape. 3. The photomask according to claim 1, wherein a tapered acute-angled portion is formed on one side of the opening or the light-shielding portion in the vertical direction. 4. The opening or the light-shielding portion is formed to be substantially symmetrical in the lateral direction, and at least over 180 degrees.
The photomask according to any one of claims 1 to 3, wherein the above corners are provided substantially symmetrically in the lateral direction. 5. A tapered acute-angled portion is formed on the axis of symmetry of the opening or the light-shielding portion and on one side in the vertical direction of the opening or the light-shielding portion. Item 5. The photomask according to item 4. 6. A method for manufacturing a liquid crystal display device using the photomask according to claim 1, wherein a photosensitive resin layer is formed directly on the substrate or via another member. And a step of patterning the formed photosensitive resin layer into a predetermined shape by exposing the formed photosensitive resin layer using the photomask, and directly or on another member on the patterned resin layer. And a step of forming a reflective film via the above.