JP2000267253A - Method for formation of exposure mask and production of liquid crystal device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a specified pattern at a desired position on a substrate with good accuracy and to apply this method for the formation of a black matrix pattern on the color filter side of a liquid crystal device so as to obtain a liquid crystal device with high dimensional accuracy, by correcting the position of the pattern on the mask according to an exposure mask when the exposure mask bends by its weight. SOLUTION: Each light-shielding pattern 11a, 11b on a mask substrate 10 is formed taking the elongation of the mask in consideration so that the distance of the pattern from the substrate center is shorter than the distance of the light-shielding pattern 12a, 12b from the substrate center with no elongation. The correction amt. in the distance of each light-shielding pattern is determined according to the size of the substrate, the position on the substrate or the like. The correction amt. is practically determined by experimentally forming a pattern by using the mask without correction, measuring the misalignment of the each pattern from the normal position by using an optical device or the like and regarding the misalignment as the correction amt., or determined by calculation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposure technique using a mask, and more particularly to an effective technique used for forming a pattern of a liquid crystal device.

[0002]

2. Description of the Related Art Conventionally, in a manufacturing process of a liquid crystal device, two glass substrates are joined by hardening an ultraviolet-curing resin or a thermosetting resin applied to the periphery at a predetermined minute interval, and bonding the two substrates. A technique of manufacturing a liquid crystal device by enclosing a liquid crystal therein is used.

For example, in a process of an active matrix type liquid crystal display device, a matrix-like pixel electrode is formed on a glass substrate and a switching element (TFT: Thin Film Transistor or TFD:
A thin film diode is provided, and a color filter layer and a counter electrode corresponding to the pixel electrode are formed and joined to the counter substrate to form a liquid crystal device. The position of each pixel electrode and the color filter layer is determined. If it shifts, the display image quality deteriorates. Therefore, it is required that the precision of the pattern dimension formed on each substrate is high.

[0004]

In the process of the conventional liquid crystal device, generally, a pattern such as electrodes of a plurality of liquid crystal panels is formed on one large glass substrate, and then the element side substrate and the color filter side substrate are formed. Are bonded to each other with an adhesive and then cut into individual liquid crystal panels. The pattern of the electrodes and the like on each substrate is formed by sequentially exposing each panel using a stepper device because the pattern on the element side substrate is complicated and more precise patterning is required. On the other hand, since the color filter side substrate has a relatively simple pattern, a method of exposing a large substrate including a plurality of panel patterns using a glass mask such as quartz glass or low expansion glass may be employed. .

However, in the exposure technique using a glass mask as described above, the mask deflects as shown in FIG. 5 due to the weight of the glass, and as a result, the distance of the pattern transferred to the substrate 20 is reduced. It has been found that there is a disadvantage that it deviates from the design value. Specifically, in the case of a rectangular quartz glass substrate having a thickness of 5 mm and a side of 400 to 500 mm, the central portion is deflected by about 25 μm, and the position of the pattern is shifted by up to 2 μm.

In particular, when the pattern forming method is different, such as the above-mentioned stepper forming a pattern of electrodes and the like on the element-side substrate and forming a black matrix pattern on the color filter-side substrate using a glass mask. Since the pattern formed on the color filter-side substrate has a larger dimensional error, the positional deviation between the pattern on the element-side substrate and the pattern on the color filter-side substrate is larger.

In addition, in the case of a glass mask, if it bends due to its own weight, the size of the pattern on the mask itself becomes large, so that in a liquid crystal device, a positional shift occurs between the pattern on the element side substrate and the pattern on the color filter side substrate. .

Further, in the case of forming a pattern using a glass mask, when the mask is bent by its own weight, the inclination becomes larger toward the periphery of the mask. That is, if the patterns have the same area on the substrate, the projected area becomes smaller toward the periphery. Since the amount of elongation of the mask and the amount of change in the projected area due to the deflection of the mask differ depending on the position on the mask, the dimensional error of the actually formed exposure pattern is different from the amount of elongation and the amount of change in the projected area. Influence each other and get complicated.

An object of the present invention is to provide a method of forming an exposure mask capable of forming a pattern with a small dimensional error in exposure using a mask.

Another object of the present invention is to provide a technique of manufacturing a liquid crystal device having a high aperture ratio with a small displacement between the pattern on the element side substrate and the pattern on the color filter side substrate.

[0011]

According to the present invention, in order to achieve the above object, when the deflection due to its own weight is so large that it cannot be ignored, the pattern on the exposure mask is determined in advance by taking into account the amount of elongation of the exposure mask due to its own weight. For example, the distance from a reference point such as the center of a mask substrate is formed to be shorter than the distance when it is assumed that there is no elongation. Preferably, each pattern on the exposure mask is formed to have a smaller size in consideration of the elongation of the mask.

The present invention is particularly effective when a plurality of liquid crystal device patterns are arranged on the mask substrate in the vertical and horizontal directions, respectively.
This is because such a substrate is relatively large, and the larger the size, the larger the size of the exposure mask used and the larger the amount of deflection.

Further, according to the present invention, one of the two substrates to be joined is subjected to pattern formation by a stepper,
In a liquid crystal device manufacturing method in which the other substrate is formed with a single mask, the pattern on the exposure mask of the substrate on which the pattern is formed with one exposure mask is taken into account in consideration of the amount of mask elongation. And the distance from the reference point is
The pattern was formed so as to be shorter than the distance assuming that there was no elongation, and the pattern was formed using the exposure mask.

According to the above-described means, when the exposure mask bends under its own weight, the position of the pattern on the mask is corrected accordingly, so that a predetermined pattern can be accurately formed at a desired position on the substrate. . In addition, when the present invention is applied to the formation of a black matrix pattern on a color filter side substrate of a liquid crystal device, the dimensional accuracy of the formed pattern can be increased. The accuracy of alignment with the filter layer can be increased, and as a result, the width of the black matrix can be reduced, thereby improving the aperture ratio.

Further, by setting the reference point at the center of the exposure mask, the correction amount of each pattern can be determined by utilizing the symmetry of the mask, so that the correction amount can be easily determined.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a pattern of an exposure mask for a substrate on a color filter side of a liquid crystal device which is an example of a device suitable for applying the present invention. FIG. 1 shows an exposure mask used to form a total of nine liquid crystal panel patterns on a single glass substrate, three in length and three in width, due to the size of the paper. However, the present invention is not limited to this, and more liquid crystal panel patterns may be formed.

In FIG. 1, reference numeral 10 denotes a mask substrate made of quartz glass or the like, and reference numerals 11a and 11b denote light-shielding patterns made of a chromium film or the like formed on the surface of the mask substrate 10 by applying this embodiment. Among them, 11a is a light-shielding pattern for forming a pattern necessary for a liquid crystal panel substrate such as a black matrix, and 11b is a light-shielding pattern for forming an alignment mark used for bonding the substrates. Reference numerals 12a and 12b denote light-shielding patterns formed by a conventional exposure mask that does not consider bending. In FIG. 1, reference numeral 13 denotes an alignment mark formed on the mask substrate 10 for use in aligning the mask substrate 10 with the glass substrate.

In this embodiment, as shown in FIG. 1, each light-shielding pattern 11a, 11b
Is formed such that the distance from the substrate center is shorter than the distance from the substrate center of the light-shielding patterns 12a and 12b when there is no expansion in consideration of the amount of extension of the mask in advance.

The correction amount of the distance of each light shielding pattern is determined according to the size of the substrate, the position on the substrate, and the like. Further, in the embodiment, the distance from the center of the mask substrate 10 to each pattern is corrected in accordance with the elongation of the mask, but one or four of the four corners of the mask substrate are corrected. The distance to each pattern may be corrected according to the elongation of the mask, using the center point of one of the sides as a reference point.

A specific method of determining the correction amount is to experimentally form a pattern using a mask that is not corrected in advance and measure the amount of deviation of each pattern from a normal position using an optical device or the like. , A method of using the shift amount as a correction amount,
There is a method of obtaining by calculation. In any of the methods, when the center of the mask is used as a reference point, the light-shielding pattern on the mask substrate is symmetrically arranged, and therefore, as shown in FIG. It is only necessary to measure or calculate
The amount of correction for a pattern in one area can then be automatically determined.

Even when a pattern is experimentally formed using an exposure mask that has not been corrected in advance and the amount of displacement is measured, it is not necessary to create a new exposure mask for the experiment. Among the masks for exposure of other products, those having the same or similar size and the same or similar number of patterns may be used. Alternatively, it is also possible to estimate the shift amount by measuring the pattern of another product formed by such an exposure mask.

FIG. 3 shows a second embodiment of the present invention.
As in FIG. 1, reference numerals 11a and 11b denote light-shielding patterns formed on the mask substrate 10 by applying this embodiment,
Reference numeral 2b denotes a pattern formed by a conventional exposure mask that does not consider bending. In the first embodiment, the pattern on the mask is formed such that the distance from the center is shorter than the distance when there is no extension in consideration of the amount of extension of the mask in advance. In the above, in addition to the above-described distance correction, the size, that is, the size of each pattern is formed to be small in advance in consideration of the elongation amount of the mask.

Next, a description will be given of a method of aligning a mask and a glass substrate when a pattern is formed on a glass substrate of a liquid crystal device using the exposure mask of the above embodiment.

On the mask substrate 10, rectangular frame-shaped alignment marks AM1 as shown in FIG. 4A are formed on a pair of opposing sides as shown in FIG.
On the other hand, a cross-shaped alignment mark AM
2 are formed. First, the alignment mark AM1
The rough alignment is performed by moving the glass substrate so that the alignment mark AM2 is located inside the substrate. next,
Alignment marks AM1 and AM with image sensor
The amount of reflected light from the second alignment mark is detected, and the direction and the amount of displacement of both alignment marks are calculated.

Since two alignment marks AM1 and AM2 are provided on each of the mask and the glass substrate, the direction and the amount of deviation between the marks are calculated for the other alignment mark in the same manner as described above. Ask by. Then, from the direction and amount of these shifts, the shift between the midpoint O1 of the alignment mark AM1 and the midpoint O2 of the alignment mark AM2 is calculated, and FIG.
The substrate is moved so that the midpoints O1 and O2 coincide with each other as shown in FIG.

Alternatively, an optical device (such as a camera)
The camera or the table is moved so that the alignment marks AM1 and AM2 are located at the centers of the fields of view, and the coordinates of the alignment marks AM1 and AM2 are obtained.
From the coordinates, each pair of alignment marks AM1 and AM2
The coordinates of the respective midpoints O1 and O2 are obtained by calculation. Then, the mask and the glass substrate may be aligned so that the obtained midpoints O1 and O2 match.

FIG. 4 shows a method of aligning the substrate in the horizontal direction (X direction). By performing the alignment in the vertical direction (Y direction) of the substrate in the same manner, a more accurate position can be obtained. Matching becomes possible.

As described above, the exposure mask for forming a black matrix pattern on the color filter side substrate constituting the liquid crystal device has been described as an example. However, other than the black matrix, for example, a transparent electrode pattern on the color filter side substrate may be formed. It can also be applied to the case. Note that the color filter layer of the color filter side substrate may be formed using an exposure mask in the same manner as in the above embodiment, but since high accuracy is not required as much as a black matrix, the color filter layer is formed by a printing method without using a mask. Is also good.

The color filter side substrate on which a black matrix or the like is formed using the exposure mask of the above embodiment is
Separately, using a stepper or the like, the device is bonded to the element-side substrate on which the electrode pattern and the like are formed at a predetermined interval by an adhesive, and then cut along the boundary (scribe area) of each liquid crystal device before the liquid crystal is removed. Enclosed.

Thereafter, for example, TAB (Tape Automated B)
The driving circuit board on which the driving IC is mounted by the onding (automated tape mounting) method is an ACF (Anisotropic Conducti
ve Film: anisotropic conductive film).
In addition, the driving I / O is performed by COG (Chip On Glass) method.
The structure in which C is directly mounted and mounted on the terminal electrode of each substrate may be adopted. And necessary power supply circuit and control circuit,
It is configured as a liquid crystal display device including a lighting device such as a backlight.

In the above description, as an example, an exposure mask for forming a pattern on a color filter side substrate constituting a liquid crystal device has been described. However, the present invention is not limited to a liquid crystal device, and a relatively large exposure mask may be used for a substrate. It can be widely used in a manufacturing process for forming a pattern thereon.

[0033]

As described above, according to the present invention,
When the exposure mask bends under its own weight, the position of the pattern on the mask is corrected in accordance therewith, so that there is an effect that a predetermined pattern can be accurately formed at a desired position on the substrate. Further, by applying the present invention to the formation of the black matrix pattern on the color filter side of the liquid crystal device, a liquid crystal device having high dimensional accuracy can be obtained. As a result, a liquid crystal display device having a high aperture ratio and good display quality can be obtained. Can be realized.

[Brief description of the drawings]

FIG. 1 is a plan view showing a first embodiment of an exposure mask for a color filter side substrate of a liquid crystal device which is an example of a device suitable for applying the present invention.

FIG. 2 is a plan view showing a second embodiment of an exposure mask for a color filter-side substrate of a liquid crystal device which is an example of a device suitable for applying the present invention.

FIG. 3 is a plan view for explaining a method of determining a correction amount of each pattern of an exposure mask when a reference point is set at a mask center.

FIG. 4 is an explanatory view showing a method for aligning an exposure mask and a substrate on which a pattern is formed by the mask.

FIG. 5 is an explanatory cross-sectional view showing a problem in forming a pattern on a substrate using a conventional exposure mask.

[Description of Signs] 10 Mask substrate 11a, 11b Light-shielding pattern 12a, 12b Light-shielding pattern of conventional exposure mask AM1, AM2 Alignment mark

Claims (6)

[Claims] 1. A pattern on an exposure mask is formed so that a distance from a reference point is shorter than a distance when it is assumed that there is no extension in consideration of an extension amount of the exposure mask due to its own weight. A method for forming an exposure mask. 2. The method according to claim 1, wherein the reference point is set at the center of the exposure mask. 3. A pattern according to claim 1, wherein each pattern on the exposure mask is formed to have a smaller size in consideration of the amount of extension of the exposure mask due to its own weight.
3. The method for forming an exposure mask according to item 1. 4. A method for manufacturing a liquid crystal device, wherein one of two substrates to be joined is exposed using a stepper, and the other substrate is exposed using an exposure mask. The pattern on the mask is formed such that the distance from the reference point is shorter than the distance when it is assumed that there is no elongation, taking into account the amount of elongation of the exposure mask due to its own weight, and exposing using the exposure mask. And a method for manufacturing a liquid crystal device. 5. The method according to claim 4, wherein the reference point is set at the center of an exposure mask. 6. The method according to claim 1, wherein the one substrate is a substrate on which a pixel electrode and a switching element are formed, and the other substrate is a substrate on which a color filter layer, a black matrix, and a transparent electrode are formed. 6. The method for manufacturing a liquid crystal device according to claim 4, wherein an exposure mask formed as described above is used for forming a matrix pattern.