JPH0990412A - Production of liquid crystal display device and liquid crystal display device produced by the process - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a voltage holding rate and to make display with high quality and high contrast free from unequal display and burn by forming a black insulator on a first substrate, then washing the substrate with a specific solvent. SOLUTION: A washing stage is included in the process after the formation of the black insulator. The washing is preferably executed by using the org. solvent. Namely, the black insulator is washed with the solvent after the formation thereof, by which the ions in the black insulator are extracted by the solvent. Such components which are dissolved to generate ions by an oriented film solvent are previously removed. The washing by such solvent is effective even after the formation of the oriented film. The ion components in the black insulator previously diffuse into the oriented film when oriented film is formed prior to the washing by the solvent. The black insulator is partially dissolved by the oriented film solvent and is conceivably held diffused in the oriented film. The ionic impurities diffused into the oriented film may be extracted by executing the washing by the solvent in this state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a liquid crystal display device having a non-linear element and a liquid crystal display device manufactured by using the method.

[0002]

2. Description of the Related Art A conventional example of a liquid crystal display device using an amorphous silicon thin film transistor (hereinafter abbreviated as TFT) as a non-linear element will be described below.

FIG. 2 is a plan view of a liquid crystal panel portion of such a liquid crystal display device, and FIG. 3 is a sectional view taken along the line AA 'of FIG. First, the gate wiring 2 made of chromium and the transparent pixel electrode 3 made of ITO are formed on the first glass substrate (array substrate) 1, and then the gate insulating film 4 made of silicon nitride is deposited on the entire surface. Further, a semiconductor layer 5 made of amorphous silicon is formed, a hole 6 is opened in the gate insulating film,
The source wiring is formed so as to partially overlap the semiconductor layer, and the drain electrode 7 is formed so as to partially overlap the semiconductor layer and the hole 6. Then, a black stripe 8 for hiding each wiring is formed by photolithography with a black insulating material.
By such a method, compared with the case where the black dielectric is provided on the second substrate (counter substrate), the deviation with respect to the wiring can be reduced, and the gap between the pixel electrodes can be effectively shielded. .

[0004]

However, in the liquid crystal display device using the conventional black insulator as described above, ionic impurities generated from the black insulator, dissolved ions by a solvent such as an alignment film, and the like. Seeping into the liquid crystal, the voltage holding characteristics deteriorate and the contrast decreases,
There is a problem in that display unevenness and printing occur.

Therefore, an object of the present invention is to solve the problems in the conventional liquid crystal display device as described above and to provide a liquid crystal display device which can obtain a high voltage holding ratio, and thus a high contrast and a high quality display. To do.

[0006]

A method of manufacturing a liquid crystal display device according to the present invention for achieving the above object is characterized by including a cleaning step after forming a black insulator. The washing is preferably performed using an organic solvent.

[0007]

According to the present invention, by washing with a solvent after forming a black insulator, the ions in the black insulator are extracted by the solvent, and the ions are dissolved by the alignment film solvent to generate ions. Such components can be removed in advance. Such cleaning with a solvent is effective even after forming the alignment film. If the alignment film is formed before cleaning with a solvent, the ionic components in the black insulator will diffuse into the alignment film in advance, or a part of the black insulator will be dissolved by the alignment film solvent and diffuse into the alignment film. It is thought that it is in a state of doing. By washing with a solvent in this state, the ionic impurities diffused in the alignment film can be extracted. As a result, even if the liquid crystal is injected, the diffusion of impurity ions into the liquid crystal is eliminated, so that the voltage holding ratio does not decrease, and finally a liquid crystal display device of good display quality without display unevenness or image sticking is obtained. You can

This washing step is carried out separately from the washing step after development when a black resist is used, or the usual washing step after array formation and before panel formation.
Further, it is effective to wash with an organic solvent having a high washing ability such as isopropyl alcohol.

3 (a) to 1 (c) show three embodiments of the present invention in a concrete liquid crystal manufacturing process. The manufacturing process shown in these figures is a process of forming a black insulator (also referred to as a black dielectric) on the first substrate and then attaching the panels, and FIG. 1A shows the black insulator formation. An embodiment in which cleaning is performed later. 1B shows an embodiment in which cleaning is performed after the alignment film is cured, and FIG. 2C shows an embodiment in which cleaning is performed after the rubbing treatment. For comparison, a conventional process without cleaning is shown in FIG.

[0010]

EXAMPLES Examples corresponding to the above-described embodiment will be described below. First, after forming an array, a negative photosensitive resist was applied by a spinner, exposed and developed, and washed with water to form a black insulator. Then, by immersing in isopropyl alcohol for 5 minutes, cleaning was performed as shown in FIG. Then, the panel was washed with water for 10 minutes and dried, and then an alignment film was printed, followed by curing and rubbing. After that, a panel was manufactured by a usual method.
Polyimide was used for the alignment film.

For testing the voltage holding ratio, a panel with electrodes without an array was prepared by the above method.
When the retention rate was measured by applying a predetermined voltage waveform, a good retention rate of 97% was obtained at 60 ° C. Incidentally, the liquid crystal panel produced by the conventional process not including the solvent washing process had a retention rate of 80% at 60 ° C.

Further, as shown in FIG. 1B, when a panel having a non-linear element after the alignment film is cured is washed,
The contrast was 150 or more, and good display characteristics without unevenness or image sticking were obtained. On the other hand, in the panel with the non-linear element manufactured by the conventional process that does not include the cleaning process,
The contrast was as low as 50, and many unevenness and burning occurred.

When cleaning was performed using Schumma, γ-butyl lactone, N-methylpyrrolidone or the like instead of isopropyl alcohol, the same effect was obtained. Such an effect is not limited to the case of using these solvents. The array configuration is not limited to the array configuration shown in FIG.

Further, as shown in FIG. 1 (b), after the alignment film was cured and the rubbing treatment was performed, and then the above-mentioned cleaning was performed, the same effect as described above was obtained. in this case,
The voltage holding ratio was 95%, which was slightly lower than that in the case of the steps of FIGS. 1B and 1C.

Note that the cleaning effect was improved by applying ultrasonic waves or the like during cleaning. It was also confirmed that the cleaning effect was improved by increasing the temperature and performing the cleaning. That is, the voltage holding ratio is further increased and the display characteristics are further improved.

[0016]

As described above, the liquid crystal display device manufactured by the method for manufacturing a liquid crystal display device of the present invention exhibits a high voltage holding ratio, and as a result, it has high contrast and high quality without display unevenness and burning. You can get the display.

[Brief description of drawings]

FIG. 1 is a manufacturing process diagram of a liquid crystal display device according to an embodiment of the present invention.

FIG. 2 is a plan view of a liquid crystal display device.

3 is a sectional view taken along the line AA ′ of the liquid crystal display device of FIG.

FIG. 4 is a manufacturing process diagram of a conventional liquid crystal display device.

[Explanation of symbols]

 1 Glass Substrate 2 Gate Wiring 3 Pixel Electrode 4 Gate Insulation Film 5 Source Electrode 6 Hole in Gate Insulation Film 7 Drain Electrode 8 Black Insulator

Claims (4)

[Claims] 1. A pixel electrode is connected to each intersection of a matrix wiring composed of a plurality of row electrodes and a plurality of column electrodes via a non-linear element, and the wiring is provided so as to cover one or both of the row electrode and the column electrode. A first substrate on which a black insulating member is formed,
A method of manufacturing a liquid crystal display device, comprising filling a liquid crystal between a second substrate having a transparent electrode, wherein a black insulator is formed on the first substrate and then washed with a predetermined solvent. A method for manufacturing a liquid crystal display device. 2. The method for manufacturing a liquid crystal display device according to claim 1, wherein the solvent is an organic solvent. 3. A pixel electrode is connected to each intersection of a matrix wiring composed of a plurality of row electrodes and a plurality of column electrodes via a non-linear element, and along the wiring so as to cover one or both of the row electrode and the column electrode. A liquid crystal display device comprising: a first substrate on which a black insulating member is formed; a second substrate having a transparent electrode; and a liquid crystal sandwiched between the first and second substrates. The liquid crystal display device is characterized in that the black insulator is formed on the first substrate and then washed with a predetermined solvent. 4. The liquid crystal display device according to claim 3, wherein the solvent is an organic solvent.