JP2002040452A - Method for manufacturing plastic liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a plastic liquid crystal display device by which a transparent electrode pattern can be formed while dissolving a problem of shift in position without giving damages to the plastic substrate itself. SOLUTION: The exposure process in the photolithographic process to form the film of a transparent electrode pattern is carried out by using a photomask designed in such a manner that the dimension from the center line of the plastic substrate to each point of the transparent electrode pattern after the film is the multiplied value of the dimension from the center line of the plastic substrate to each point of the region where the transparent electrode pattern is to be formed when the formation of a color film layer previously formed on the plastic substrate is completed by the elongation/shrinkage magnification of the substrate dimension after the completion of the exposure in the forming process of the transparent electrode pattern to the substrate dimension when the formation of the color film layer is completed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a plastic liquid crystal display device, and more particularly to a method for manufacturing a plastic liquid crystal display device characterized by an exposure method for forming a transparent electrode pattern.

[0002]

2. Description of the Related Art A plastic liquid crystal display device using a plastic substrate has been evaluated for being lighter and less susceptible to cracking than a glass substrate, and has been highly expected in the fields of mobile phones and portable information terminals. ing. In particular,
In the information terminal field, as the amount of information expands, the screen resolution increases and the size of the screen increases.Therefore, there is a limit to the weight reduction of liquid crystal display devices using glass substrates, and the development of plastic liquid crystal display elements is expected. Recently, in particular, there is a great demand for color liquid crystal display elements.

Here, the structure of a general color liquid crystal display element 1 will be briefly described. As shown in FIG. 2, there is provided two transparent substrates 2 which are arranged substantially in parallel at an interval. The outer periphery between these transparent substrates 2 is hermetically sealed by a sealing material 8. Of the transparent substrate 2, a transparent electrode 3 (signal electrode 3A) made of ITO (indium tin oxide) or the like is arranged on the lower surface of a transparent substrate (hereinafter, FRONT substrate) 2A located above in the figure. Below the signal electrode 3A and the exposed FRONT substrate 2A, an alignment film 4 for controlling the alignment of liquid crystal molecules in accordance with a voltage applied between the electrodes is provided so as to be in close contact.

On the other hand, a black matrix 5 is disposed on the upper surface of a transparent substrate (hereinafter, referred to as a CF substrate) 2B which is located below the FRONT substrate 2A in the figure and faces the opening 5a of the black matrix 5. Has color filters 6 of three colors of red (R), green (G), and blue (B), which are colored films. As a method of forming the color filter 6, various methods such as a printing method, an electrodeposition method, a dyeing method, and a pigment dispersion method are used. A protective film 7 is provided above the color filter 6 and the black matrix 5, and a transparent electrode 3 made of ITO or the like is further provided above the color filter 6 and the black matrix 5. The alignment film 4 is provided so as to be in close contact.

A liquid crystal (not shown) is provided in a sealed space surrounded by the transparent substrates 2A and 2B and the sealing material 8.
Are implanted, and a plurality of spacers (not shown) are interposed between the alignment films 4 in order to keep a constant gap between the transparent substrates 2A and 2B.

In the color liquid crystal display element 1 having such a structure, when a glass substrate is used as the transparent substrate 2, an ITO film pattern 3B as the transparent electrode 3 of the CF substrate 2B is obtained by applying a resist solution to the glass substrate. rear,
Prebake to form a photoresist film, then
A photomask is arranged in alignment with the alignment mark on the glass substrate, and a region where the color filter is formed is exposed to UV light to form a predetermined pattern.

[0007]

However, when a plastic substrate is used as the transparent substrate 2, the plastic substrate itself swells by absorbing moisture during the process.
Since the thermal expansion causes thermal expansion and a dimensional change in the vertical and horizontal directions, the above-described ITO film pattern 3B is formed using a photomask for a glass substrate which does not need to consider the dimensional change. The ITO film pattern 3B located away from the center line including the alignment mark of the substrate has caused a positional shift in the direction away from the center line. In other words, when several film layers are formed on a plastic substrate, the plastic substrate at the time of forming the upper layer film to be laminated later is smaller than the plastic substrate at the time of forming the lower film layer already laminated. It expands and contracts due to various processes on the plastic substrate up to the process, for example, a heating process in a protective film forming process, a substrate cleaning process, an ITO film forming process in an ITO film pattern forming process, a resist coating process, a pre-baking process, and the like. . Therefore, a problem of misregistration occurs at the time of exposure in the step of forming the ITO film pattern 3B which requires alignment with the color filter formed in the lower layer.

Further, since the plastic substrate is inferior to the glass substrate in rigidity of the substrate itself, warpage and undulation are likely to occur.
B has caused the displacement.

The displacement of the ITO film pattern 3B is shown in FIG.
As shown in the figure, the color filter 6 on the CF substrate 2B and the IT
A portion that does not overlap with the O film pattern 3B is formed. This reduces the effective area as a pixel,
It appears as a defect that the display quality of the color liquid crystal display element 1 is inferior.

Conventionally, in order to solve these problems, a method of applying a heat treatment to the plastic substrate or a method of performing a vacuum treatment before the exposure has been adopted. However, such a method increases the number of working steps, There was a problem of damaging the plastic substrate itself.

Accordingly, an object of the present invention is to provide a method of manufacturing a plastic liquid crystal display device capable of forming a transparent electrode pattern by solving the problem of positional displacement without damaging the plastic substrate itself. It is assumed that.

[0012]

In order to achieve the above-mentioned object, a method of manufacturing a plastic liquid crystal display device according to the present invention comprises a method of aligning a first film layer already formed on a plastic substrate with a photo film. In a method of manufacturing a plastic liquid crystal display element for forming a film on a predetermined second film pattern by photolithography having an exposure step using a mask, the exposure is performed from the center line of the plastic substrate after the formation of the second film pattern. Of the plastic substrate at the time of completion of the formation of the first film layer, and the dimensions from the center line of the plastic substrate to each point of the region where the second film pattern is to be formed at the time of completion of the formation of the first film layer. A photomask designed to be a size obtained by multiplying the substrate size by the expansion / contraction magnification of the substrate size at the time of completion of the exposure in the second film pattern forming step. Is characterized in that performed are.

According to the present invention, the second film pattern formed on the plastic substrate can reduce the changed dimensional difference even if the plastic substrate undergoes a dimensional change due to swelling, thermal expansion, or the like in the flow process of manufacturing the substrate. Since the design dimensions are considered in advance, it is possible to prevent the first film layer and the second film pattern from being displaced on the substrate separated from the alignment mark portion of the plastic substrate.

According to a second aspect of the present invention, in the method of manufacturing a plastic liquid crystal display device, the first film layer is a colored film layer.
The second film pattern is a transparent electrode pattern.

According to the present invention, it is possible to easily perform the alignment between the color filter composed of the colored film layer and the transparent electrode pattern, which requires particularly high alignment accuracy, without requiring any special process. , A color liquid crystal display device having a high density can be produced.

According to a third aspect of the present invention, there is provided a method of manufacturing a plastic liquid crystal display device according to the first or second aspect, wherein the plastic substrate is a gas barrier coat on at least one surface of a base substrate. It is characterized by having a layer.

According to the present invention, the plastic substrate is inferior to the glass substrate in terms of rigidity, and the plastic substrate itself can be prevented from warping or undulating.
In the transparent electrode forming step, if exposure is performed using a photomask for a plastic substrate, the displacement of the transparent electrode pattern separated from the alignment mark on the plastic substrate can be completely prevented.

[0018]

An embodiment of the present invention will be described below with reference to FIG.

In this embodiment, the ITO film pattern 3 of the CF substrate 2B is used as an example of the formation of the transparent electrode pattern in the method of manufacturing a color plastic liquid crystal display device.
This relates to exposure at the time of forming B, and the other manufacturing steps are based on the conventional manufacturing steps, and description thereof is omitted. The same members as those in the above-described conventional example are denoted by the same reference numerals and described.

The CF substrate 2B used for manufacturing the color liquid crystal display element 1 is made of 0.1-0.4 mm polycarbonate, polyarylate, polyethersulfone or the like having a gas barrier coat layer on both sides of the base substrate. A plastic substrate is used.

The black matrix 5 is arranged on the plastic substrate. The black matrix 5 includes a light-transmitting opening 5a and a light-blocking light-shielding portion 5b. The light-transmitting opening 5a is provided with a color filter 6 made of a color film layer of three colors of RGB. Deploy. A protective film 7 is provided above the color filters 6 and the black matrix 5.

In the present embodiment, a photomask 9 for a plastic substrate designed as follows.
To form an ITO film pattern 3B as the transparent electrode 3 in accordance with the formation position of the color filter 6 formed in the lower layer.

That is, the photomask 9 used in the present embodiment is formed of the plastic substrate which is caused by various processes applied from the completion of the formation of the color filter 6 to the exposure in the step of forming the ITO film pattern 3B. The exposure is performed using the photomask 9 in the method of manufacturing a plastic liquid crystal display device of the present embodiment in consideration of the expansion and contraction of the device itself.

Normally, a plastic substrate used as the transparent substrate 2 is a substrate formed isotropically or a substrate from which anisotropy has been removed. However, the substrate is still affected by moisture, heat and the like as described above. It is undeniable that the plastic substrate is slightly expanded and contracted in the vertical and horizontal directions. For example, the plastic substrate made of the above-mentioned polyethersulfone differs in the expansion and contraction ratio between the stretching direction when forming the substrate and the anti-stretching direction. Therefore, evaluation regarding the expansion and contraction of the plastic substrate is performed in advance.

In order to evaluate the expansion and contraction of the plastic substrate, a plastic substrate made of the same material and configuration as the plastic substrate actually used is prepared as a sample, and the plastic substrate is used in a flow process for manufacturing a normal plastic liquid crystal display element. Substrate dimensions at the completion of formation of the color filter 6;
The substrate size at the time of completion of the exposure in the formation process of the TO film pattern 3B is measured, and the expansion / contraction magnification of the substrate size at the time of completion of the exposure in the formation process of the ITO film pattern 3B with respect to the substrate size at the completion of formation of the color filter 6 is obtained. Things.

This evaluation is desirably performed in both the vertical and horizontal directions of the plastic substrate. In addition, a plurality of plastic substrates to be sampled are prepared, and one expansion / contraction magnification is finally determined in one direction by a method such as calculating an average value in consideration of measurement errors and product errors of the substrates. I do.

For example, the expansion / contraction magnification used in a specific example of the present embodiment described later was obtained as follows.

The plastic substrate as a sample for which the expansion ratio was determined in the examples is a 0.2 mm thick plastic substrate having a gas barrier coat layer made of SiOx on both surfaces of a base substrate made of polycarbonate. It was formed 260 mm in width and 300 mm in the horizontal direction. Ten samples of this sample were prepared, and the above-described evaluation of the expansion and contraction was performed on each sample. As a result, the expansion and contraction magnification of the plastic substrate in the vertical direction upon completion of the exposure in the process of forming the ITO film pattern 3B was 1.02 ± 0.
Since a numerical value of 003 was obtained, the expansion / contraction magnification in the vertical direction was finally determined to be 1.02.

Similarly, the expansion / contraction ratio in the horizontal direction is
As a result, a numerical value of 1.02 ± 0.004 was obtained.
It was decided to be 2.

Then, a photomask 9 for a plastic substrate is designed based on the expansion / contraction magnification.

In the present embodiment, the photomask 9 is moved from the center line of the plastic substrate after film formation by IT.
The dimension up to each point of the O film pattern 3B is the dimension up to each point of the center line of the plastic substrate and the area where the ITO film pattern 3B is to be formed when the formation of the color filter 6 is completed (hereinafter referred to as an initial dimension). To
The design is made to have a size obtained by multiplying the expansion / contraction magnification obtained earlier.

Hereinafter, a specific example of the design of the photomask 9 for a plastic substrate will be described with reference to FIG.

At the center of the photomask 9 in the vertical direction, an alignment mark 1 for matching an alignment mark (not shown) provided at the center of the plastic substrate in the vertical direction.
0A is provided, and an alignment mark 10B is formed at the center in the horizontal direction to match the alignment mark provided at the center in the horizontal direction of the plastic substrate.

First, the design position in the vertical direction of the photomask 9 in the formation region of each ITO film pattern 3B is set such that the size from the vertical center line 11A to the formation region of each ITO film pattern 3B is set to the initial size. It is designed to have a dimension multiplied by 1.02 as a multiplier.

Specifically, as shown in FIG. 3, a point A (A in the figure) represents an outer edge portion of a formation region of the ITO film pattern 3B formed farthest from the vertical center line 11A. A point B (B in the figure) represents an inner edge of the same ITO film pattern 3B forming area as the point A, and
In a case where the outer end side of the formation area of another ITO film pattern 3B formed on the vertical center line 11A is point C (C in the figure), the vertical center of the photomask 9 for a plastic substrate is set. Assuming that the initial design dimension between the vertical center line 11A and the point A is X, the dimension between the line 11A and the point A is X (the initial design dimension between the vertical center line and the point A) × 1. It is 1.02X by the relational expression of .02 (expansion / contraction magnification). Similarly, the dimension between the vertical centerline 11A and the point B is 1.02Y, where Y is the initial design dimension between the vertical centerline 11A and the point B, and the vertical centerline. Assuming that the initial design dimension between the vertical center line 11A and the point C is Z, the dimension between the vertical center line 11A and the point C is 1.02.
Z.

Although not shown, similarly, the design dimensions of the formation region of the ITO film pattern 3B in the lateral direction of the photomask 9 are from the horizontal center line 11B to the formation region of each ITO film pattern 3B. Is obtained by multiplying the initial dimension of the above by 1.02.

The ITO film pattern 3 thus obtained
A photomask 9 for a plastic substrate is designed based on the design dimensions of the B formation region.

Then, the photomask 9 for the plastic substrate, in which the design dimensions of the formation region of each ITO film pattern 3B are adjusted from the center lines 11A and 11B in both the vertical and horizontal directions, is formed on the alignment mark formed on the photomask 9. The desired ITO film pattern 3B is formed by arranging the color filters 6A and 10B so as to correspond to the alignment marks formed on the plastic substrate, and exposing the formation region of the color filter 6 with UV light.

The ITO film pattern 3B formed on the plastic substrate in this way has a design dimension in which even if the plastic substrate undergoes a dimensional change due to swelling, thermal expansion or the like in the flow step, the changed dimensional difference is considered in advance. Therefore, the ITO film pattern 3B formed apart from the center line including the alignment mark of the plastic substrate
Can be solved.

The method of this embodiment does not apply heat treatment or vacuum treatment to the plastic substrate, so that the plastic substrate itself is not damaged and the photomask 9 for the plastic substrate is once formed without damaging the plastic substrate itself. Once designed and prepared, the photomask 9 can be used in a normal flow process as long as a plastic substrate of the same standard is used, so that the number of working steps does not particularly increase.

As the plastic substrate, a base substrate having a gas barrier coat layer formed thereon as described above was used. The gas barrier coat layer was formed of, for example, SiOx or the like, and this gas barrier coat layer was formed at least on the base substrate. Forming on one side, preferably on both sides, covers the point where the plastic substrate is inferior in rigidity to the glass substrate. By providing a gas barrier coat layer on a plastic substrate, warpage and undulation of the substrate itself can be prevented. In the process of forming a transparent electrode, if exposure is performed using a photomask 9 for a plastic substrate, alignment on the plastic substrate can be achieved. It is possible to completely eliminate the positional deviation of the transparent electrode pattern separated from the center line including the mark.

Note that the present invention is not limited to the above-described embodiment, and various modifications can be made as necessary.

For example, in the above embodiment, the formation of the transparent electrode pattern on the CF substrate has been described as an example, but the plastic substrate is not limited to the above-described substrate. In short, the present invention is a technique that can be applied to an exposure method in a process of forming another film layer while overlaying another film layer while performing alignment using an alignment mark above an already formed film layer. For example, the present invention may be applied to a case where a colored film pattern as a second film is formed on information in which a reflective film layer is formed as a first film layer.

[0044]

As described above, according to the present invention, it is possible to form a transparent electrode pattern without damaging the pattern, without damaging the plastic substrate itself. A plastic liquid crystal display device capable of obtaining a certain display quality in a display region of a panel can be manufactured.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram relating to the design of a photomask for a plastic substrate used in the present invention.

FIG. 2 is a sectional view showing the structure of a general color liquid crystal display device.

FIG. 3 is a schematic diagram showing a displacement of an ITO film pattern.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Color liquid crystal display element 2 Transparent substrate 2A FRONT substrate 2B CF substrate 3 Transparent electrode 3A Signal electrode 3B ITO film pattern 4 Alignment film 5 Black matrix 5a Opening 5b Shielding part 6 Color filter 7 Protective film 8 Sealing material 9 Photomask 10A ( (Vertical direction of photomask) alignment mark 10B (horizontal direction of photomask) alignment mark 11 center line 11A (vertical direction of photomask) center line 11B (horizontal direction of photomask) center line

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G09F 9/30 310 G09F 9/30 310 5G435 343 343Z 349 349B F term (Reference) 2H088 EA02 FA16 FA18 FA29 HA02 MA20 2H090 JA07 JB03 JC07 JD11 JD15 JD18 LA01 LA15 2H091 FA02Y FA35Y FD04 FD05 GA01 GA03 GA07 LA30 2H092 GA15 HA04 JB52 JB56 MA13 MA14 NA25 NA29 PA01 PA08 5C094 AA05 AA05 AA15 AA04 EB01 EB04 EB01 EB04 FB15 GB10 5G435 AA01 AA04 AA17 BB12 CC09 FF05 GG12 HH02 HH12 KK05

Claims (3)

[Claims] 1. A photolithography method having an exposure step using a photomask while performing positioning on a first film layer already formed on a plastic substrate. In the method of manufacturing a plastic liquid crystal display element for forming a second film pattern, the exposure is performed when a dimension from a center line of the plastic substrate to each point of the second film pattern after film formation is completed. In the dimension from the center line of the plastic substrate to each point of the second film pattern formation scheduled area,
It is characterized by using a photomask designed to be a size obtained by multiplying the substrate size at the time of completion of exposure in the second film pattern forming step by the expansion / contraction magnification of the substrate size at the time of completion of the formation of the first film layer. Manufacturing method of plastic liquid crystal display element. 2. The method according to claim 1, wherein the first film layer is a colored film layer, and the second film layer is a colored film layer.
2. The method according to claim 1, wherein the pattern is a pattern comprising a transparent electrode. 3. The method for manufacturing a plastic liquid crystal display device according to claim 1, wherein said plastic substrate has a gas barrier coat layer on at least one surface of a base substrate.