JPH05150249A - Liquid crystal display device and its manufacture - Google Patents

Abstract

PURPOSE:To prevent a spacer from falling in the display area or on the display electrode of the active matrix liquid crystal display device and to eliminate deterioration in the display quality due to the presence of the spacer. CONSTITUTION:The orienting film 55 on the display electrode 35 is charged up to the negative polarity to discharge electrostatic charges in the orienting film 55 corresponding to a light shield film 53 through the light shield film 53. When spacers which are charged up to the negative polarity are scattered, the spacers reaching the area surrounded with the light shield film 53 are repelled and arranged except in the display area since the orientation film 55 in this area is charged to the negative polarity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device which further improves display characteristics and a manufacturing method thereof.

[0002]

2. Description of the Related Art In a liquid crystal display device, liquid crystal is injected into a gap between two glass substrates, and a spacer is used to keep the gap between the substrates constant. As these techniques, (a) a method of using a sealing material mixed with a spacer and holding a gap by a spacer in a sealing part (b) a method of spraying spacers after solidifying an alignment film on a substrate (c) ) A general method is to coat the spacers with an adhesive and spray the spacers on the alignment film formed on the substrate.

On the other hand, as a method of spraying spacers, there is, for example, Japanese Patent Application Laid-Open No. 1-225919. In this,
Wet and dry methods are mentioned. The wet method is a method in which spacer particles are added to a dispersion liquid such as Freon and stirred, and then this solution is sprayed from above the substrate by spraying nitrogen gas from a spray nozzle, and the solution reaches the substrate. By this time, the dispersion is completely scattered and dried.

The dry method is a method in which spacer particles are directly dispersed in nitrogen gas without using a dispersion liquid, and the spacer particles are jetted from a spray nozzle as a solid gas two-layer flow. In any of these methods, the spacers (1) are randomly distributed as shown in FIG. Quadrangle (2)
The area indicated by is the display electrode or the display area. For example, in the case of the active matrix type, other switching elements and the like are formed, but they are omitted here.

[0005]

As shown in FIG. 2, there is a problem that the display quality is deteriorated when the spacer (1) is present on the display electrode (2). FIG. 3 is a diagram for explaining the deterioration of the display quality, showing a state in which a voltage is applied to a normally white TN cell, and is shown on the outside of two glass substrates (3) and (4) sandwiching a spacer. Is a polarizing plate (5),
(6) is provided. The glass substrate (3),
A liquid crystal (7) shown by a dotted line is filled between (4). Of course, there are various components on the facing surfaces of the glass substrates (3) and (4), but they are omitted here.

A polarizing plate (5) is provided in a portion where there is no spacer.
Since the light passing through the liquid crystal (7) does not change its polarization state even if it passes through the liquid crystal (7), it does not pass through the polarizing plate (6) arranged such that the polarization axis is orthogonal to the polarizing plate (5). .. On the other hand, around the spacer (1), the alignment of liquid crystal or the twist state is disturbed, and the light passing through the polarizing plate (5) is
The polarization state is disturbed by the liquid crystal (7) around the spacer (1) and is transmitted through the polarizing plate (6).

For these reasons, if the spacer exists on the display electrode (2) or in the display area, light leakage occurs and the display quality deteriorates. This issue is active,
It occurs regardless of the simple matrix type.

[0008]

The present invention has been made in view of the above-mentioned problems, and at least an electrode (51) and a light shielding film (53).
A transparent first insulating substrate (50) provided with an alignment film (55), at least an electrode (35), a second transparent insulating substrate (30) provided with an alignment film; 1
Insulating substrate (51) and the second insulating substrate (30)
In a liquid crystal display device in which a liquid crystal is injected between the spacer (56) and the spacer (56) for setting a predetermined interval, the spacer (56) is provided with an alignment film (55) corresponding to the light shielding film (53).
The solution is to disperse

Furthermore, a transparent first insulating substrate (30)
A plurality of address lines (31) and a plurality of data lines (41) insulated from each other via an insulating layer (36)
And the source electrode (42) of the TFT formed at this intersection
A display electrode (35) electrically connected to the first insulating substrate (30), an alignment film substantially provided on the entire surface of the insulating substrate (30), and a transparent second electrode facing the first insulating substrate (30). In the liquid crystal display device having at least the counter electrode (51), the light-shielding film (53) and the alignment film (55) formed on the insulating substrate (50), the light-shielding film (53) has conductivity, An insulating layer (52) is provided on the lower layer for insulation from the counter electrode (51), and an alignment film (55) for preventing the escape of charges is provided on the light shielding film (53). ) On the alignment film (55) corresponding to the spacer (5
This is solved by dispersing 6).

Further, a plurality of address lines (31) and a plurality of data lines (41) provided on the transparent first insulating substrate (30) via an insulating film (36) are provided at the intersections. Forming a switching element, a display electrode (35) electrically connected to the switching element, and an alignment film provided on the entire surface, and transparent facing the first insulating substrate (30). Counter electrode (51) provided on the second insulating substrate (50), and the counter electrode (51)
Insulating layer (52) provided on this insulating layer (52)
A step of forming a conductive light-shielding film (53) provided on the light-shielding film and an alignment film (55) provided on the light-shielding film (53) in which charge does not easily escape, and one of the light-shielding film (53) Part is exposed to the external atmosphere, or this light-shielding film (5
Part of 3) is grounded, the charge of the alignment film (55) corresponding to the light shielding film (53) is discharged to the outside, and the charge is left in the display region, and the second insulating substrate (50). The spacers (56) are sprayed on the upper surface, and the spacers (56) are repelled by the charge remaining in the display area, and the spacers (56) are scattered on the alignment film (55) corresponding to the light shielding film (53). And the first insulating substrate (3
0) and the second insulating substrate (50) are opposed to each other and sealed, and a liquid crystal is injected between the pair of substrates (30) and (50). is there.

[0011]

The present invention can be solved by dispersing spacers on the light-shielding film in order to improve display characteristics and eliminating the spacers dispersed in the display area surrounded by the display area. However, since the spacers are dispersed from the spray nozzle, they are randomly arranged. However, the spacer is charged up, and in the alignment film on the counter substrate side, in the region surrounded by the light-shielding film, the same polarity as that charged in the spacer is charged up, so that the region surrounded by the light-shielding film is charged. We found that the spacers that reach can be repelled and that they can be scattered outside this area.

The light-shielding film is formed of a conductive material, and an alignment film, such as an organic polymer, in which charges are unlikely to escape is formed on the light-shielding film. After the formation of this alignment film, the alignment film is negatively charged up, for example, by rubbing or ion probe. However, it is not necessary if the alignment film is charged up by the process before this process. After that, the light-shielding film formed in the lower layer of the alignment film is electrically grounded, or a part of the light-shielding film is exposed to the external atmosphere, and the charge of the alignment film above the light-shielding film is discharged to the outside. Since the alignment film in the region surrounded by the light-shielding film is not in contact with the light-shielding film, the charge is not discharged through the light-shielding film, and the charge is less reduced. Therefore, if the charged spacers are sprayed, the spacers repel and become stable outside the display area.

As a characteristic of the alignment film, a sheet resistance higher is more likely to be charged or less likely to escape to the outside. For example, when polyimide is used, it is preferable that the sheet resistance is almost completely imidized because the sheet resistance is high. ..

[0014]

EXAMPLES Examples of the present invention will be described below. The present invention can be applied to an active matrix type that requires a light shielding film, particularly a TFT or the like using amorphous silicon or polysilicon. Before explaining a specific example, the basic principle will be described first. First, in order to prevent the display quality from being deteriorated by the spacer, it is possible to provide the spacer in the display region or in the region where the light shielding film is not formed, because the alignment or twist state of the liquid crystal is not disturbed. Further, since the spacers are scattered in the region where the light shielding film is formed, the gap between the pair of glass substrates sandwiching the spacer is kept constant.

To disperse the spacers on the alignment film in the region corresponding to the light-shielding film, first, the alignment film on the counter substrate is charged up to one polarity and then charged through the conductive light-shielding film formed in the lower layer. When discharged to the outside, charges remain only in the alignment film on the display area surrounded by the light shielding film. Therefore, if the spacers have the same polarity as the charges, the spacers reaching the display area repel and are scattered on the alignment film corresponding to the light shielding film.

As a method of charging the alignment film
Can be achieved simply by rubbing. But Aeonbu
By applying a rho to the surface of the alignment film, it can be positive or negative.
Can be achieved more reliably. The spacer is generally made of resin.
It is contained in the spraying device and is N in the dry method.
₂Spray with gas. The spacers should be
Because they are rubbing against each other, they naturally charge up negatively.
Have been Furthermore, the spacer is forcibly vibrated.
Rubbing against each other, applying an electric field,
-It can be charged up. Latter two
You can also add a positive charge up.
In the wet method, volatile agents such as freon and ethanol,
Is H ₂O is used, but with the previous two volatilizers, charge
Up is possible. The spray sprayed from the spray nozzle
The pacer rubs against the surrounding atmosphere after the volatilizer evaporates.
I will naturally charge. Immediately before reaching the substrate,
You may forcibly charge up with low etc. here
Examples of the spacer material include styrene resin and benzo.
Guanamine resin is used.

An embodiment applied to an active matrix type liquid crystal display device will be described with reference to FIGS. 1, 4, 5 and 6. Here, a TFT structure using amorphous silicon is used for explanation, and a detailed cell structure is shown in FIG. First, as can be seen from FIGS. 5 and 6, there is a transparent insulating substrate (30) on which a plurality of gate lines (31) and a plurality of gate lines (31) substantially parallel to the gate lines (31) are provided. Book auxiliary capacitance lines (32) are provided. This gate line (31) is, for example, about 150
The gate line (31) is provided with a region which is made of Cr of 0Å and extends to the left and right, and this region is used as a gate (33) of the TFT. Further, since the auxiliary capacitance electrode (34) is formed at the same time as the gate line (31), the auxiliary capacitance electrode (34) is made of Cr and has a thickness of about 1500Å.
In order to be integrated with the auxiliary capacitance electrodes adjacent to the left and right,
An auxiliary capacitance line (32) extends parallel to the gate line (31).

A gate insulating film (36) covering the gate line (31) integrated with the gate (33) and the auxiliary capacitance line (32) integrated with the auxiliary capacitance electrode (34), and the auxiliary capacitance electrode (34). And a non-doped non-single-crystal silicon film (37) laminated on the interlayer insulating layer corresponding to the gate (33), and a display electrode (35) made of ITO superposed on the silicon film (37). A laminated N ⁺ type non-single crystal silicon film (38) is provided.

The gate insulating film is made of SiNx and is formed on the surface of the glass substrate to a thickness of about 4000Å.
On the interlayer insulating layer on which the TFT is formed, for example, non-doped amorphous silicon (hereinafter referred to as a-Si layer) (37) and N ⁺ -type amorphous silicon (hereinafter referred to as N ⁺ a-Si layer). (38) are laminated. The a-Si layer (37) is approximately 1000 Å
And the N ⁺ a-Si layer (38) has a thickness of about 50 nm.
It is formed with a thickness of 0Å. In addition, the a-Si layer and N ⁺ a
A semiconductor protective film (39) of about 2500 Å made of SiNx may be provided between the -Si layer and the -Si layer.

Further, a drain electrode (40) electrically connected to the drain region, and a plurality of drain lines (41) integrally formed with the drain electrode and extending in a direction orthogonal to the gate line (31). ) And a display electrode (3) electrically connected to the source region and provided in a region surrounded by the drain line (41) and the gate line (31).
5) and the source electrode (42) electrically connected.

The drain electrode (40) and the drain line (41) integrated with the drain electrode (40) have a two-layer structure of Mo and Al. The lower layer Mo has a thickness of about 1000 Å and the upper layer Al has a thickness of about 7 liters.
It is made of 000Å. The display electrode (35) is IT
Although it is made of O and the source electrode is formed of a two-layer structure of Mo and Al like the drain electrode, it may be integrally formed of ITO.

The structure up to this point (a sectional view taken along line AA in FIG. 4) is shown in FIGS. Although the gate insulating film has one layer in FIG. 5, it has two layers in FIG. 6 and the lower layer has about 3 layers.
The SiN _x film of 000A, but the upper layer is made from the SiN _x film of about 2000 Å, the SiO ₂ film as an upper layer or a lower layer film, or both two layers may be used. The upper gate insulating film (35) covers the periphery of the display electrode,
The main surface is exposed by etching.

Further, although not shown, final passivation is formed, or this passivation is omitted and the alignment film is directly formed. On the other hand, FIG. 1 shows a perspective view of a counter substrate, in which IT is formed on a transparent insulating substrate (50).
There is a counter electrode (51) made of a transparent electrode such as O. On this counter electrode, SiN _X, insulating layer of an organic film having a SiO ₂ or heat-resistant (52) is provided. A light shielding film (53) made of, for example, Cr is formed on the insulating layer. The opening area of the light shielding film corresponds to the area (54) surrounded by the short diagonal lines shown in FIG. Further, an alignment film (55) is formed on the light shielding film. Then, the two glass substrates (30), via the spacer (56),
The periphery of (50) is sealed, and liquid crystal is injected into it to obtain this device.

Here, the arrangement state of the alignment film (55) and the spacer (56) and the arrangement method of the spacer are the features of the present invention. As the alignment film, a polymer film having a high sheet resistance is used. For example, when using polyimide,
It is preferably substantially completely imidized. This is because the sheet resistance becomes high and charging up becomes easy if the polymerization is completed.

This alignment film is coated with a technique such as PI printing after cleaning the substrate, and after being cured, subjected to a rubbing treatment. After that, the film is washed again, and the entire surface is ion-blown to negatively charge up the alignment film. Alignment film (5
Since the conductive light-shielding film (53) is formed under 5), the light-shielding film is electrically grounded like the earth symbol in FIG. The charge of the alignment film corresponding to can be removed. Alternatively, a part of the light-shielding film may be exposed so as to come into contact with the external atmosphere, and the charge of the alignment film can be released to the outside from this exposed region as indicated by an arrow indicating that the negative ions are released to the outside.
For example, the charge can be released by providing an exposed region of the light-shielding film on the outer periphery of the region to be the screen and allowing the exposed region to stand for a while.

The charge remaining on the alignment film naturally disappears if left for a long time. Therefore, if a negatively charged spacer is sprayed from a spacer nozzle before the charge disappears, a display surrounded by a light-shielding film is displayed. The spacer (56 ') reaching the area repels and moves onto the alignment film corresponding to the light-shielding film. Since the repulsive force is large when the amount of charge is large, most of it is scattered on the light-shielding film, but when the amount of charge is small, the repulsive force becomes small and some remain in the display area. However, most of it moves from the center of the display area to the periphery.

After the spacers have been dispersed, the substrate on which the sealing resin is applied around the substrate and the TFT is formed is bonded to the counter substrate, and the liquid crystal is injected therein. Up to this point, we proceed with a large glass substrate so that multiple panels can be removed. Then, after being broken into a plurality of panels by a glass cutter or the like, a defective product is removed through an inspection process, and polarizing plates are arranged on both sides of the panel to complete.

The method of spraying the spacers by charging the alignment film has been described above, but the spacers can be fixed to the counter substrate by the following method. First, as shown in FIG. 7, a light-shielding film (62) having a light-shielding ability is formed on a transparent insulating substrate (61) serving as a counter substrate having a counter electrode (60). Figure 8
As described above, in order to pattern the light shielding film (62), a photoresist (63) is formed and etching is performed.
At this time, spacers (64) are mixed in the photoresist, and the photoresist corresponding to the display electrodes is etched to form openings. As shown in FIG. 9, if the light shielding film is etched through the opening, a light shielding film having a predetermined shape is formed. Normally, after this, there is a photoresist removing step, but here, by leaving this photoresist, the spacers remain in the region corresponding to the light shielding film.

Further, an alignment film may be formed on the entire surface of the substrate, and the alignment film may be attached to the above-described insulating substrate having the TFT formed thereon.
Although the inverse stagger type a-Si TFT has been described as an example of the active matrix type, it goes without saying that a stagger type, inverse stagger type or stagger type polysilicon TFT can also be used.

[0030]

As is clear from the above description, since the spacer does not drop on the display electrode, it is possible to prevent deterioration of display quality. Further, miniaturization of display electrodes can be considered in order to achieve high-density pixels in the future, but spacers do not drop on the display electrodes, which is effective for high-vision and the like.

Further, since the ion blow is performed on the side of the counter substrate on which the TFT is not formed, the element is not destroyed by these charges, so that the yield can be improved. Further, if spacers are mixed in the resin used as a photoresist, it can be achieved by the conventional process without adding any additional process.

[Brief description of drawings]

FIG. 1 is a schematic diagram illustrating spacer dispersion on a counter substrate of a liquid crystal display device of the present invention.

FIG. 2 is a schematic diagram illustrating how spacers are dispersed in a conventional liquid crystal display device.

FIG. 3 is a diagram illustrating a reduction in display quality due to a spacer.

FIG. 4 is a plan view of a liquid crystal cell used in the present invention.

5 is a cross-sectional view taken along the line AA of FIG.

6 is a cross-sectional view taken along the line AA of FIG.

FIG. 7 is a diagram illustrating a spacer arrangement method.

FIG. 8 is a diagram illustrating a spacer arrangement method.

FIG. 9 is a diagram illustrating a spacer arrangement method.

[Explanation of symbols]

10 Display Area 20 First Substrate 21 First Electrode Line 22 Alignment Film 23 Second Substrate 24 Second Electrode 26 Alignment Film 27 Spacer 30 Transparent Insulating Substrate 31 Gate Line 33 Gate 35 Display Electrode 36 Gate Insulation Film 37 a-Si Film 38 N ⁺ a-Si film 40 Drain electrode 41 Drain line 42 Source electrode

Claims (5)

[Claims] 1. A transparent first insulating substrate provided with at least an electrode, a light-shielding film, and an alignment film, a second transparent insulating substrate provided with at least an electrode, an alignment film, and the first transparent substrate. In a liquid crystal display device in which an insulating substrate and the second insulating substrate are set at a predetermined distance, and a liquid crystal is injected between the spacers, the spacers are dispersed in an alignment film substantially corresponding to a light shielding film. A liquid crystal display device characterized in that 2. The liquid crystal according to claim 1, wherein an organic film having spacers mixed therein is formed between the light shielding film and the alignment film in a pattern formed in a region where the light shielding film is formed. Display device. 3. A plurality of address lines and a plurality of data lines, which are insulated from each other through an insulating layer on a transparent first insulating substrate, and a source electrode of a TFT formed at this intersection and an electric field. Electrically connected display electrodes, an alignment film substantially provided on the entire surface of the insulating substrate, and a counter electrode formed on a transparent second insulating substrate facing the first insulating substrate, In a liquid crystal display device having at least a light-shielding film and an alignment film, the light-shielding film has conductivity, an insulating layer is provided below the light-shielding film for insulation from a counter electrode, and an upper layer above the light-shielding film is provided. A liquid crystal display device characterized in that an alignment film is provided to prevent the charge from escaping, and spacers are dispersed on the alignment film corresponding to the light shielding film. 4. A plurality of address lines and a plurality of data lines provided on a transparent first insulative substrate via an insulating film and a switching element provided at an intersection of the plurality of address lines and a plurality of data lines, and the switching element electrically. A step of forming a display electrode connected to the first insulating substrate and an alignment film provided on the entire surface, and a counter electrode provided on a transparent second insulating substrate facing the first insulating substrate. A step of forming an insulating layer provided on the electrode, a conductive light-shielding film provided on the insulating layer, and an alignment film provided on the light-shielding film, in which charge is hard to escape, and Exposing a part of the light-shielding film to the outside atmosphere or grounding a part of the light-shielding film, discharging the charge of the alignment film corresponding to the light-shielding film to the outside, and leaving the charge in the display region; Display by spraying spacers on a flexible substrate A step of repelling the spacers by the charge remaining in the region to disperse the spacers on the alignment film corresponding to the light-shielding film, and the first insulating substrate and the second insulating substrate are opposed to each other. A method for manufacturing a liquid crystal display device, comprising at least a step of sealing and a step of injecting liquid crystal between the pair of substrates. 5. A plurality of address lines and a plurality of data lines provided on a transparent first insulating substrate via an insulating film and a switching element provided at an intersection of the plurality of address lines and a plurality of data lines, and an electrical connection between the switching element and the switching element. A step of forming a display electrode connected to the first insulating substrate and an alignment film provided on the entire surface, and a counter electrode provided on a transparent second insulating substrate facing the first insulating substrate. A step of forming a light-shielding film provided on the electrode, a step of forming a photoresist mixed with spacers on the entire surface, and patterning the photoresist into a predetermined shape of the light-shielding film, and an opening of the photoresist. A step of etching the light-shielding film, a step of forming an alignment film on the entire surface while leaving the photoresist, and a step of sealing the first insulating substrate and the second insulating substrate so as to face each other. A step, preparation method of the liquid crystal display device wherein at least a step of injecting a liquid crystal between the pair of substrates.