JPH0437720A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To offer the liquid crystal display device which is uniform in contrast among respective parts of the screen and has no display defect by providing a columnar cell interval holding material made of an insulator on an insulting film for protecting the surfaces of thin film transistors(TFT) and picture element electrodes. CONSTITUTION:In an active matrix liquid crystal display, a front glass substrate 2 and a rear glass substrate 3 hold a liquid crystal layer 4 across the insulators 12 which are formed at specific positions on the insulating film 10 to uniform thickness. The insulators 12 are formed preferably in areas on the insulating film 10 where no TFT 8 is arranged, and further preferably in areas facing a black matrix 6 on the front glass substrate 2. Thus, the insulators 10 are formed in the above mentioned areas, then the damaging of respective electrodes of the TFTs 8 can be evaded when the front glass substrates 2 and rear glass substrate 3 are stuck one over the other, and the aperture rate of picture elements is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a liquid crystal display device, and more particularly to an active matrix liquid crystal display.

[Prior Art J] FIG. 2 is a sectional view schematically showing a configuration example of a conventional active matrix liquid crystal display.

Traditional active matrix liquid crystal displays
As shown in the figure, a liquid crystal layer 27 is sandwiched between a front glass substrate 22 bonded together by a sealing layer 21 and a rear glass substrate 25 provided with a thin film transistor 23 and a pixel electrode 24 via a spacer 26.

A counter electrode 28 made of a transparent electrode material such as ITO is provided on the front glass substrate 22, a black matrix 29 is provided on the counter electrode 28, and an alignment film 30 is provided on the black matrix 29. ing.

On the other hand, the front glass substrate 2 of the back glass substrate 25
On the surface facing 2, a plurality of data line electrodes and scanning electrodes are formed in a stripe shape orthogonal to each other, and a thin film transistor 23 is provided at the intersection of the two electrodes. Further, the pixel electrode 24 is provided between the two electrodes, and the pixel electrode 24 is connected to the thin film transistor 23. The thin film transistor 23 and the pixel electrode 24 are disposed on the thin film transistor 23 and the pixel electrode 24.
An insulating film 31 is provided to protect the surface of the substrate 4, and an alignment film 32 is provided on the insulating film 31.

In the conventional active matrix liquid crystal display having the above configuration, the pixel electrode 24 and the counter electrode 28
Display is performed by applying a voltage between the two electrodes to change the arrangement state of the liquid crystal between the two electrodes. Therefore, in order to make the contrast of each part of the screen uniform, there is a gap between the front glass substrate 22 and the rear glass substrate 25. It is necessary to keep the thickness (cell spacing) of the liquid crystal layer 27 constant. Therefore, spacers 26 made of glass fiber, ceramic, or resin and molded into a spherical or cylindrical shape having a uniform diameter are scattered between the front glass substrate 22 and the rear glass substrate 25. A liquid crystal layer 27 is sandwiched between the rear glass substrate 25 and a spacer 26 .

The diameter of the spacer 26 is normally set appropriately within the range of 3 to 10 μm.

The conventional active matrix liquid crystal display mentioned above is
After the spacers 26 are scattered on the back glass substrate 25, the front glass substrate 22 and the back glass substrate 25 are bonded together by being pressurized and fixed via the sealing layer 21.

[Problems to be Solved by the Invention] However, in the above-mentioned conventional active matrix liquid crystal display, the spacers are scattered irregularly on the rear substrate, so the spacers may be placed in undesired positions. There's a problem.

For example, if the spacers sprinkled on the rear substrate are located above the thin film transistors, the spacer between the front and rear substrates will be pressurized because in active matrix liquid crystal displays, the cell spacing is narrow where the thin film transistors are formed. When fixed and bonded together, the spacer may press the drain electrode (data line electrode) or gate electrode (scanning line electrode) constituting the transistor, damaging the electrode. Damage to the above electrode is
The electrodes are often disconnected.

If the train electrode or the source electrode is disconnected, the data signal or scanning signal will not be transmitted to the entire panel, causing display defects in the active matrix liquid crystal display.

Therefore, the present invention has been made to solve the problems of the prior art as described above, and its purpose is to:
It is an object of the present invention to provide a liquid crystal display device which has uniform contrast in each part of the screen and is free from display defects.

[Means for Solving the Problems] A liquid crystal display device according to the present invention includes: a first substrate provided with a thin film transistor and a pixel electrode; a second substrate provided with an electrode facing the pixel electrode; In a liquid crystal display device comprising a liquid crystal layer provided between the first and second substrates, an insulator provided at a predetermined position on the first and second substrates or the first substrate. It is characterized in that the liquid crystal layer is sandwiched between the two.

[Function] In the liquid crystal display device of the present invention, a columnar cell spacing member made of an insulator is formed on an insulating film for protecting the surfaces of the thin film transistor and the pixel electrode. Since the insulator is formed to have a uniform thickness at each part on the insulating film, by sandwiching the liquid crystal layer between the front substrate and the rear substrate or the insulator, the liquid crystal layer can be formed without using a spacer.
The cell spacing of the liquid crystal layer in each part of the screen is maintained constant.

Furthermore, since the insulator can be formed at a desired position on the surface protection film, it can be formed avoiding the thin film transistor area, which makes it easier to bond the front and rear substrates together, unlike spacers that are scattered irregularly. At this time, the rain electrode or gate electrode is not compressed.

Therefore, according to the present invention, the cell spacing in each part of the screen can be made uniform, and damage to each electrode of the thin film transistor can also be avoided.

[Example code] The present invention will be explained below based on illustrated embodiments.

FIG. 1 is a cross-sectional view schematically showing an embodiment of an active matrix liquid crystal display according to the present invention. The active matrix liquid crystal display of this embodiment has a first
As shown in the figure, a front glass substrate 2 and a rear glass substrate 3
are bonded together by a sealing layer 1, and a front glass substrate 2 is attached.
A liquid crystal layer 4 is provided between the rear glass substrate 3 and the rear glass substrate 3.

A counter electrode 5 made of a transparent electrode material such as ITO is provided on the front glass substrate 2, a black matrix 6 is provided on the counter electrode 5, and an alignment film 7 is provided on the black matrix 6. It is being

On the other hand, on the surface of the rear glass substrate 3 facing the front glass substrate 2, a plurality of data line electrodes and scanning electrodes are formed in a stripe shape orthogonal to each other, and a thin film transistor is located at the intersection of the two electrodes. 8 is provided. Further, a pixel electrode 9 is provided between the two electrodes, and the pixel electrode 9 is connected to the thin film transistor 8. An insulating film 10 is provided on the thin film transistor 8 and the pixel electrode 9 to protect the surfaces of the thin film transistor 8 and the pixel electrode 9, and an alignment film 11 is provided on the insulating film 10.

In the active matrix liquid crystal display of this embodiment, the front glass substrate 2 and the rear glass substrate 3 are connected to the liquid crystal display via an insulator 12 formed at a predetermined position on the insulating film 10 with a uniform thickness. It is characterized by sandwiching layer 4.

The insulator 12 is preferably formed in a region on the insulating film 10 where the thin film transistor 8 is not disposed, and more preferably in a region facing the black matrix 6 on the front glass substrate 2. preferable.

By forming the insulator 10 in the above region, each electrode of the thin film transistor 8 can be prevented from being damaged when the front glass substrate 2 and the rear glass substrate 3 are bonded together, and the aperture ratio of the pixel can be reduced. can be improved.

Examples of the material for forming the insulator 12 include silicon carbide (SiC), silicon nitride (SiN), and silicon oxide (Sin), with SiC being particularly preferred. The thickness of the insulator 12 may be arbitrarily set according to the desired cell spacing, and is usually 3 to 3.
It is set to a value in the range of about 10 μm.

The shape of the surface of the insulator 12 parallel to the glass substrate may be any shape such as a square, a rectangle, or a circle.
The cross-sectional area of the plane parallel to the glass substrate is preferably such that it can withstand the pressure applied when the front glass substrate and the back glass substrate are bonded together. The above cross-sectional area is, for example,
When the cross-sectional shape of the insulator 12 is square, 3μmX
It is preferably in the range of about 3 μm to 15 μm×15 μm.

In this embodiment, the insulator is preferably formed into a columnar shape having the shape described above.

The active matrix liquid crystal display of this example is
For example, it can be advantageously manufactured as follows.

First, a film of one of metals such as chromium (Cr), tantalum (Ta), and molybdenum (Mo) is formed on the rear glass substrate 3 by sputtering or vapor deposition to a thickness of approximately 0.1 to 0.3 μm. Form a metal film with a thickness of .

Next, the metal film is formed into a gate electrode pattern by photolithography and etching. A plurality of the gate electrodes are formed in a stripe shape.

Next, a transparent electrode material such as ITO is formed on the rear glass substrate 3 by sputtering or vapor deposition to a thickness of about 0.1 μm. Next, the transparent electrode film is formed into the pattern of the pixel electrode 9 by photolithography and etching.

Next, a SiNx film is deposited on the entire surface of the back glass substrate 3 by a plasma CVD method using NH3 and SiH4 as main component gases. A film is formed to a thickness of approximately 1 to 0.4 μm, and then an amorphous silicon (a-8i) film is deposited on the entire surface of the rear glass substrate 3 by a plasma CVD method using SiH4 as the main component gas. The film is formed to a thickness of about 0.2 μm. Then, the above S r N
The x film and the a-8i film are formed into a predetermined pattern by photolithography and etching. SiN is formed by the above steps.

A gate insulating film is formed from the film, and a semiconductor film is formed from the a-3i film.

Next, aluminum (AI) is applied to the entire surface of the rear glass substrate 3.
, nickel (Ni), chromium, molybdenum, copper (Cu)
Nichrome (N
A metal film having a thickness of about 0.3 to 1.0 μm is formed by depositing one of the alloys such as iCr) by sputtering or vapor deposition. Next, the metal film is formed into a predetermined pattern by photolithography and etching.

Through the above steps, a data line electrode, a drain electrode, and a source electrode are respectively formed. In the above step, a plurality of the data line electrodes are formed in a stripe shape perpendicular to the gate electrode, and the drain electrode is formed integrally with the data line electrode at the intersection of the data line electrodes. There is.

The thin film transistor 10 is configured by the gate electrode, gate insulating film, semiconductor film, drain electrode, and source electrode. The thin film transistor 10 is formed at the intersection of the data line electrode and the gate electrode.

Next, an insulating film 10 made of SiN x is formed on the entire surface of the rear glass substrate 3. The SiN film may be formed by a plasma CVD method using NH3 and SiHa as main component gases. The insulating film 10 has a function of protecting the surfaces of the thin film transistor 8 and the pixel electrode 9.

Next, a SiC film is formed on the entire surface of the rear glass substrate 3 to a thickness of about 3 to 10 μm by plasma CVD using 5IH4 and ethylene as main component gases. Next, the SiC film is formed into a predetermined pattern by photolithography and etching. Through the above steps, columnar insulators 12 are formed. The insulator 12 is preferably formed in a region on the insulating film 10 where the thin film transistor 8 is not disposed, and is preferably formed in a region on the front glass substrate 2 that is scheduled to face the black matrix 6. More preferred.

Next, the entire surface of the rear glass substrate 3 is coated with 0. A polyimide film having a thickness of about 1 μm is formed, and the polyimide film is subjected to a rubbing treatment to form an alignment film 12.

This completes the manufacture of the back glass substrate provided with the thin film transistor and pixel electrode.

In the above manufacturing method, it is preferable that the insulator 12 is formed after the insulating film 10 is formed and before the alignment film 11 is formed.

If the insulator 12 is formed after the alignment film 11 is formed, the surface of the alignment film 11 that has been rubbed may be damaged due to etching or the like during the formation of the insulator film 12.

Also, if the alignment film 11 is formed after the formation of the insulator 12, the alignment process of the alignment film 11 may be insufficient in the vicinity of the insulator 12. By forming it in the area where the alignment process is to be performed, it is possible to reduce the influence on the display of the portion where the alignment treatment is insufficient near the insulator 12.

Next, a transparent electrode material such as ITO is formed on the front glass substrate 2 by sputtering or vapor deposition to a thickness of about 0.1 μm to form a counter electrode 5.

Next, a black matrix 6 is formed in a region on the counter electrode 5 that is scheduled to face the thin film transistor 8 . The black matrix 6 may be formed using materials and methods known per se. Next, the entire surface of the front glass substrate 2 is coated with 0.
A polyimide film having a thickness of about 1 μm is formed, and the polyimide film is subjected to a rubbing treatment to form an alignment film 7.

Next, a 3 to 10μ
A polymeric insulating material containing a molded body made of glass fiber, ceramic or resin in a spherical or cylindrical shape having a substantially uniform diameter in the range of m is formed into a film in a predetermined pattern by a thick film screen printing method, and the sealing layer 1 is formed into a film by a thick film screen printing method. form.

Examples of the polymer insulating material include polymer resins such as epoxy, acrylic, and polyester resins. The thickness of the sealing layer 1 may be arbitrarily set according to the desired cell spacing, and is usually set appropriately in the range of 5 to 20 μm.

Next, the rear glass substrate provided with the thin film transistor 8 and pixel electrode 9 and the front glass substrate are arranged so that the surface provided with the thin film transistor 8 and pixel electrode 9 and the surface provided with the counter electrode 6 face each other. In this way, the two substrates are bonded together by aligning and pressurizing and fixing them using the seal layer 1, and heating and curing the polymer insulating material of the seal layer 1. At this time, the insulator 12 functions to maintain a constant distance between the liquid crystal layer 4 between the rear glass substrate and the front glass substrate, but since it is formed in an area where the thin film transistor 8 is not arranged, The pressurizing operation described above does not damage the electrodes constituting the thin film transistor 8.

Next, the interior of the back glass substrate and front glass substrate bonded together using the sealing layer 1 is vacuum degassed, and the injection port (
(not shown) to complete the manufacture of the active matrix liquid crystal display.

[Effects of the Invention] As explained in detail above, according to the liquid crystal display device of the present invention, the cell spacing of the liquid crystal layer is maintained by the insulator formed to have a uniform thickness, so that the cell spacing is uniform in all parts of the screen. In addition, since the insulator is formed in a region where no thin film transistor is disposed, the electrode of the thin film transistor is not damaged during the manufacturing process, and therefore display defects can be reduced.

[Brief explanation of drawings]

FIG. 1 is a sectional view schematically showing an embodiment of an active matrix liquid crystal display according to the present invention, and FIG. 2 is a sectional view schematically showing an example of the configuration of a conventional active matrix liquid crystal display. 2... Front glass substrate, 3... Back glass substrate, 12... Insulator.

Claims (1)

[Claims] A first substrate provided with a thin film transistor and a pixel electrode, a second substrate provided with an electrode facing the pixel electrode, and a substrate provided between the first and second substrates. and a liquid crystal layer, wherein the first and second substrates sandwich the liquid crystal layer via an insulator provided at a predetermined position on the first substrate. A liquid crystal display device featuring: