JP2000187227A - Production of liquid crystal device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To execute jointing with lessened misalignment between pixel electrodes and color filters layers by designing in advance the patterns of an exposure mask for production of a substrate on a side to be irradiated with UV rays or heat rays which are set smaller than the patterns of an exposure mask for production of a substrate on an opposite side and jointing the substrates formed by these exposure masks to each other. SOLUTION: A spacing L1 of patterns 21 and alignment marks AM1 on the element side substrate 11 on a side opposite to the side irradiated with UV rays is so designed in advance as to be made larger by as much as the component meeting the shrinkage rate after jointing in the stage of designing of the exposure masks. The exposure mask is so formed that the spacing L2 of the patterns 22 and alignment marks AM2 on the color filter side substrate 12 on the side irradiated with the UV rays is so designed in advance as to be made smaller by as much as the component meeting the expansion rate after jointing. The alignment of the elements and the color filter side substrates 11 and 12 is executed, in such a manner that the angles of the lines connecting the alignment marks AM1 and AM2 are aligned to each other and the substrates are irradiated with the UV rays.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technology effective when applied to a device constituted by precisely aligning two substrates and joining them with a resin or the like, and is used, for example, for manufacturing a liquid crystal device. The present invention relates to a technique suitable for:

[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 bonded to the counter substrate to form a liquid crystal device. The positions of the pixel electrodes and the color filter layer are shifted. And the display quality deteriorates.
It is necessary to precisely align the two substrates and fix them with an adhesive.

Therefore, conventionally, an adhesive such as an ultraviolet curable resin is applied to a peripheral portion of a glass substrate on the switching element side (hereinafter, referred to as an element side substrate), and then a lower surface plate composed of a glass substrate is formed. The counter substrate (color filter side substrate) and the element side substrate are separated by a comma m using a substrate bonding apparatus including an upper surface plate having positioning and air press functions.
m, a position alignment of about several tens of μm (coarse alignment) is performed, and then two substrates are brought close to 15 to 20 μm for a position alignment of several μm (precision alignment), and then using an air press means. 0.1 to 0.8 kg / cm ^2, preferably 0.4 kg / cm ²
A technique has been proposed in which a light source is operated while applying a pressure higher by ² cm ² to an opposing substrate, and ultraviolet light is irradiated from below to cure the adhesive.

[0005]

However, in the above-described method of curing the adhesive by irradiating ultraviolet rays, the substrate on the color filter side irradiated with the ultraviolet rays thermally expands, so that the method shown in FIG. As described above, the adhesive is cured while the electrode pattern of the element-side substrate and the color filter layer of the color filter-side substrate are displaced, and thus there is a problem that an aperture ratio is reduced and display quality is reduced. It became clear. It is considered that when the temperature of the liquid crystal device to which the adhesive has been hardened and joined is lowered, the color filter-side substrate 12 contracts, and the entire substrate is curved as shown in FIG. 5B.

According to the verification of the present inventor, the length of the substrate
For 0 to 400 mm, the strain due to thermal expansion is about 4 μm. Therefore, when the adhesive is cured in a state where the pixel electrode at the center of the substrate and the color filter layer are aligned, the adhesive is cured with the pixel electrode at the edge of the substrate and the color filter layer being displaced by about 2 μm. On the other hand, the pitch of the pixel electrodes has been provided to be about 50 μm with the increase in the fineness of the liquid crystal device. Therefore, the aperture ratio is reduced by about 4% only by the thermal expansion in one direction.

An object of the present invention is to provide a technique for manufacturing a liquid crystal device in which a pixel electrode and a color filter layer can be joined with less displacement.

Another object of the present invention is to provide a liquid crystal device having a high aperture ratio and good display quality.

[0009]

According to the present invention, in order to achieve the above-mentioned object, an adhesive is applied to one of two substrates, and the other substrate is brought close to and opposed to align the substrates. In a manufacturing method of irradiating ultraviolet rays or heat rays from one side of the substrate to cure the adhesive and joining the substrates to obtain a liquid crystal device or the like, for example, a method of manufacturing a substrate on the side irradiated with ultraviolet rays or heat rays is used. The pattern of the exposure mask is designed to be smaller in advance than the pattern of the exposure mask for manufacturing the substrate on the opposite side, and the substrates formed with these exposure masks are joined together.

According to the above-described means, the adhesive formed on the substrate formed with the small exposure mask is cured by the irradiation of ultraviolet rays in a state in which the adhesive is extended more than the other substrate. Since the bonding is completed in a state where the pixel electrode of the element-side substrate and the color filter layer of the counter substrate coincide with each other in the bonding of the liquid crystal device, a decrease in the aperture ratio can be prevented.

The present invention is particularly effective when each of the substrates is formed with a plurality of electrode patterns and color filter layers of a liquid crystal device arranged in a vertical direction and a horizontal direction, respectively. This is because such a substrate is relatively large, and the larger the substrate, the larger the thermal expansion strain between the substrates.

[0012]

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

FIGS. 1A and 1B show patterns of respective substrates of a liquid crystal device which is an example of a device suitable for applying the present invention. 1A and 1B, 11 is a glass substrate serving as an element-side substrate, 12 is a glass substrate serving as a counter substrate,
Reference numeral 21 denotes a region for forming an electrode pattern made of Cr (chromium), Al (aluminum), or the like formed on the glass substrate 11 on the element side by using a photolithography technique; It is a color filter layer formed. In addition, FIG.
In (B), AM1 and AM2 are alignment marks formed on the glass substrates 11 and 12, respectively. Although not particularly limited, these alignment marks AM1 and AM2 are formed of the same material as the electrodes 21 and the color filter layers 22 provided on the respective substrates with the same exposure mask.

In this embodiment, each of the substrates 11 and 12 is separately formed with a plurality of electrode patterns (21) and a color filter layer 22 of a liquid crystal device arranged in a vertical direction and a horizontal direction, respectively. An adhesive / sealant is applied to one of the substrates 11 and 12 and joined while being aligned using an alignment mark, and after the adhesive / sealant is cured, a boundary portion (scribe area) of each liquid crystal device is formed. Is configured to be cut along.

FIGS. 2A and 2B show alignment marks AM1 and AM2 to which the present invention is applied and alignment marks AM1 'and AM formed by a conventional method.
2 'is shown. In the conventional method, as shown in FIG. 2B, an exposure mask is formed such that the intervals L1 'and L2' of the alignment marks AM1 'and AM2' are equal. On the other hand, in the case of the present invention, at the stage of designing the exposure mask, the distance L1 between the pattern 21 and the alignment mark AM1 on the substrate (the element side substrate 11 in this embodiment) on the side opposite to the ultraviolet irradiation side is determined after bonding. Is designed to increase in advance by an amount corresponding to the amount of contraction of the.

The distance L2 between the pattern 22 and the alignment mark AM2 on the substrate on the ultraviolet irradiation side (the color filter side substrate 12 in this embodiment) is previously reduced so as to be reduced by an amount corresponding to the extension amount after bonding. A mask is formed. Specifically, on a substrate having a length of about 300 mm, each substrate is set so that the distance L2 between the alignment marks AM2 on the color filter-side substrate is smaller than the distance L1 between the alignment marks AM1 on the element-side substrate by about 4 μm. The pattern of the exposure mask is designed. And
A pattern such as an electrode or a color filter layer is formed on each substrate by the exposure mask whose pattern dimension has been corrected in this way.

Here, the shape of the alignment marks formed on both substrates is generally rectangular or circular, but is not particularly limited thereto.

Next, the alignment marks AM1, A
An alignment method in the substrate bonding step using M2 will be described.

First, each of the alignment marks AM1 and AM
2 are detected. Specifically, FIG.
As shown in (A) and (B), the camera or the table is moved so that the alignment marks AM1 and AM2 of interest come to the center of the field of view of the optical device (camera or the like), and the center coordinates of each alignment mark AM1 or AM2 are set. Ask. Next, from the coordinates, each pair of alignment marks AM1 and A1
The coordinates of the midpoints O1 and O2 of M2 are calculated. Then, as shown in FIG. 3 (C), the obtained midpoints O1 and O1
The substrates 11 and 12 are aligned so that the angle of the line connecting AM1 and AM2 coincides with the coordinate of No. 2, and then ultraviolet rays are irradiated.

Therefore, even when the substrates 11 and 12 on which the alignment marks AM1 and AM2 having different intervals L1 and L2 as shown in FIG. 1 are joined, alignment can be performed without any problem.

FIG. 3 shows a method of aligning the substrate in the horizontal direction (X direction). By performing alignment in the vertical direction (Y direction) of the substrate in the same manner, a more accurate bonding can be achieved. Becomes possible. However, when the length in the vertical direction is considerably shorter than the length in the horizontal direction, it is possible to perform only the horizontal alignment using the alignment marks AM1 and AM2 described above.

As a result, the sealing agent is hardened in a state where the color filter substrate 12 formed with the small exposure mask is extended from the other element-side substrate 11 by the irradiation of ultraviolet rays. 11 electrode patterns 2
1 and the color filter layer 22 of the counter substrate 12.
Is completed in a state where the distance L2 ″ of the liquid crystal device coincides. As a result, it is possible to prevent a decrease in the aperture ratio of the completed liquid crystal device.

FIG. 4 shows an example of a substrate bonding apparatus used for manufacturing a liquid crystal device to which the present invention is applied. As shown in FIG. 4, in this apparatus, a base 32 is provided at the center of a base 31 serving as a base of the apparatus, and a lower surface plate 33 made of quartz glass having a flatness of 2 μm or less is mounted on the base 32. Is placed. The lower platen 33 has a plurality of through holes 33a penetrating vertically, and the base 32
A groove 32a communicating with the plurality of through holes 33a
By connecting one end of a pipe from a vacuum pump (not shown) to a part of the groove 32a, a vacuum chuck is formed so that the substrate 10 placed on the lower platen 33 does not laterally shift. It is constituted so that adsorption is possible.
The base 32 is also formed of a glass base, and a light source 34 for irradiating ultraviolet rays is disposed below the base.

A column 35 is erected on one side of the base 31, and a horizontal support plate 36 is rotatably mounted on the upper end of the column 35. At the center of the support plate 36, there is provided a table 37 whose position can be adjusted in the X, Y and θ directions, and a cylinder 38 is fixed to the lower surface of the table 37. A pair of vacuum suction arms 39A,
39B is hung. Further, the support plate 36
A guide member 41 for vertically supporting the vertical rod 40 is attached to the distal end of the vertical rod 40. An upper surface plate 42 having a frame 42a protruding downward at the peripheral edge is provided at the lower end of the vertical rod 40. It is fixed. An air cylinder 43 moves the upper platen 42 up and down.

In this embodiment, a gel-like rubber body 44 is adhered to the lower surface of the frame body 42a.
One end of a pipe 45 from an air pump (not shown) is connected to a part of 2 a (the upper platen 42 is also possible), and the air cylinder 43 pushes down the upper platen 42 to move the rubber body 44 to the lower platen 33. When the air pump is operated while being in contact with the substrate 20 placed on the
The structure is configured such that the pressure of air in a space surrounded by the frame and the frame body 42a increases to function as an air press that presses the substrate 20 downward.

In FIG. 4, 46A and 46B are sealed so that air does not leak from through holes 42b and 42b formed in the upper platen 42 so that the vacuum suction arms 39A and 39B can pass through. Leak prevention means 47a and 47b are cameras used for positioning.

The element-side substrate 11 and the opposing substrate (color filter-side substrate) constituting the liquid crystal device by this substrate bonding apparatus
Bonding with the second member 12 is performed according to the following procedure.
In the following description, it is assumed that the sealant is applied to the element-side substrate 11.

First, by rotating the support plate 36, a work storage unit (not shown) provided on the
Only one color filter side substrate 12 vacuum suction arm 3
Adsorbed by 9A, 39B and transferred to lower platen 33,
Place. Then, the vacuum chuck provided on the lower platen 33 is operated to hold the color filter side substrate 12 firmly on the lower platen 33 so as not to be displaced.

Next, the support plate 36 is rotated again to remove only one element-side substrate 11 to which a sealant has been previously applied from another work storage portion provided on the side of the apparatus, and the vacuum suction arm 39A, Adsorbed by 39B and lower surface plate 33
Transfer to the upper part. Then, the table 37 is controlled based on the images of the respective alignment marks obtained from the cameras 47a and 47b, and the position of the element-side substrate 11 is adjusted to perform coarse alignment of, for example, about several μm. When activated, the upper surface plate 42 is brought closer to the lower surface plate 33 to bring the element-side substrate 11 into contact with the color filter-side substrate 12 and lightly pressurized to obtain the respective images obtained based on the images from the cameras 47a and 47b. The center coordinates of the mark are calculated from the coordinates of the alignment mark, and the table 37 is controlled to shift the position of the element-side substrate 11 so that the center coordinates match, thereby performing high-precision alignment of, for example, 1 μm.

Thereafter, the vacuum suction arms 39A, 39B
Is stopped and the cylinder 38 is raised, and then the air cylinder 43 is operated to lower the upper platen 42 to bring the rubber body 44 on the lower surface of the frame body into contact with the counter substrate 12, and then the air press means is operated. The air in the space surrounded by the upper platen 42 and the frame 42a
g / cm ^2, preferably about 0.4 kg / cm ² , and applying pressure to the light source 34 while pressing the opposing substrate 12 to irradiate ultraviolet rays for about 60 seconds to apply the light to the surface of the element-side substrate 11. The sealant that has been cured is cured.

According to the above-described procedure, the element-side substrate 11 and the color filter-side substrate 12 are accurately joined together at a predetermined interval. After the bonded substrates are lifted by the air cylinder 43, the upper platen 42 is raised, the vacuum chuck on the lower platen 33 is stopped to release the bonded substrate, and then the vacuum suction arms 39A and 39B are lowered by the cylinder 38. The substrate is sucked and then raised, and the support plate 36 is rotated, so that the substrate is transferred to and stored in a substrate storage unit provided on the side of the apparatus.

In the substrate bonding apparatus shown in FIG. 4, a light source 34 for irradiating ultraviolet rays is disposed below the lower platen 33 to cure the sealant with the ultraviolet rays. Lower surface plate 3 using curable resin
A heat source, such as an infrared lamp, may be arranged below 3.

The substrate bonded as described above is cut at the boundary of each liquid crystal device, and after the liquid crystal is sealed, the substrate is driven by, for example, a TAB (Tape Automated Bonding) method. The drive circuit board on which the IC is mounted is connected via an ACF (Anisotropic Conductive Film). Also, C
The drive IC may be directly mounted on the terminal electrodes of the substrates 11 and 12 and mounted by an OG (Chip On Glass) method. The liquid crystal display device includes a necessary power supply circuit, a control circuit, and a lighting device such as a backlight.

In the above description, as an example, the case where the element-side substrate and the opposing substrate constituting the active matrix type liquid crystal device are joined has been described. However, the present invention is not limited to a simple matrix type liquid crystal device and the like, but also includes a liquid crystal device. In addition, the present invention can be widely used for a manufacturing method using a bonding apparatus that bonds two substrates and irradiates or heats ultraviolet rays from one side.

[0035]

As described above, according to the present invention,
In the manufacture of a liquid crystal device, there is an effect that bonding can be performed with a small displacement between a pixel electrode formed on each of two substrates to be bonded and a color filter layer. Further, by applying the present invention, a liquid crystal device with high alignment accuracy can be obtained, and as a result, a liquid crystal display device with a high aperture ratio and good display image quality can be realized.

[Brief description of the drawings]

FIG. 1 is a plan view showing a pattern of each substrate of a liquid crystal device which is an example of a device suitable for applying the present invention.

FIG. 2 shows an alignment mark A when the present invention is applied.
It is explanatory drawing which shows the example of M1, AM2, and the alignment mark AM1 ', AM2' formed by the conventional method.

FIG. 3 is an explanatory diagram showing a method of aligning a substrate of a liquid crystal device using an alignment mark to which the method of the present invention is applied.

FIG. 4 is a front sectional view schematically showing a substrate bonding apparatus suitable for bonding substrates of a liquid crystal device to which the present invention is applied.

FIG. 5 is a cross-sectional view showing a problem caused by a conventional liquid crystal device substrate bonding method.

[Explanation of symbols]

 AM1, AM2 Alignment mark 11 Substrate (device side substrate) 12 Substrate (color filter side substrate) 21 Electrode pattern 22 Color filter layer 31 Base 32 Base 33 Lower surface plate 32a, 33a Vacuum chuck 34 Light source 35 Support 36 Support plate 37 Table 38 Cylinder 39A, 39B Vacuum suction arm 40 Vertical rod 41 Guide member 42 Upper surface plate 42a Frame 43 Air cylinder 44 Gel rubber 45 Pipe forming air press 46A, 46B Air leak prevention means 47a, 47b Positioning camera

Claims (2)

[Claims] An adhesive is applied to one of two substrates, and the other substrate is positioned so as to face and approach the other substrate, and the substrate is irradiated with ultraviolet rays or heat rays from one of the substrates. In the method for manufacturing a liquid crystal device, comprising a step of bonding the substrates by curing the adhesive, the pattern of the exposure mask for manufacturing the substrate on the side irradiated with ultraviolet rays or heat rays is changed to the pattern of the exposure mask for manufacturing the substrate on the opposite side. A method of manufacturing the liquid crystal device, wherein the substrates are designed to be smaller in advance than each other, and the substrates formed with these exposure masks are joined to each other. 2. The device according to claim 1, wherein each of the substrates is formed with a plurality of electrode patterns and color filter layers of a liquid crystal device arranged in a vertical direction and a horizontal direction, respectively. Of manufacturing a liquid crystal device.