JPS6055383A - Transmission type liquid crystal display unit - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an active matrix transmissive liquid crystal display device.

[Technical background of the invention and its problems]

In recent years, active matrix type liquid crystal display device prototype development using a thin film transistor (TPT) using amorphous silicon or polysilicon as a switch transistor has become active. Since the TPT plate can be formed by a low-temperature process, the substrate material is not particularly limited, and it has the advantage that it can utilize at least one of the exposure and etching techniques used in conventional semiconductor devices. For this reason, it is seen as a promising device for reducing the cost, thickness, and power consumption of various displays.

Generally, a transparent glass substrate such as borosilicate glass or quartz glass, which is polished on both sides, is used as a substrate for a transmission type liquid crystal display device. In the process of integratedly forming a TFT array using these glass substrates, a TPT dirt insulating film,
S s used as interlayer insulating film and passivation film
PSG, BS with O2 film and 5to2'i as main components
The entire G film etching step is required multiple times. In this case, if the etching method is a wet type, it is necessary to use a hydrogen fluoride HF type etching solution. However, such an etching solution also etches the glass substrate containing 5i02e as a main component. As a result, the surface of the glass substrate on which the TFT array is integrated becomes cloudy and opaque. This significantly reduces the light transmittance, which is the lifeblood of a transmissive liquid crystal display device. When a TFT array is actually formed around the entire circumference of a normal borosilicate glass substrate, the light transmittance of the substrate is about 30%.

[Purpose of the invention]

In view of the above points, the present invention aims to provide an active matrix type transmission type liquid crystal display device with improved performance.

[Summary of the invention]

The present invention is characterized in that both surfaces or at least the back surface of the glass substrate on which the TFT array is integrated are coated in advance with a transparent insulating film having excellent etching resistance.

〔Effect of the invention〕

According to the present invention, despite the multiple etching steps required to form a TFT array, the transparent glass substrate is prevented from becoming cloudy and opaque, and a high-performance active matrix transmissive liquid crystal display device is realized. can do.

[Embodiments of the invention]

The figure is a sectional view showing one pixel portion of a device according to an embodiment of the present invention. The entire display device is composed of a first electrode plate 1, a second electrode plate 2, and a liquid crystal 3 sandwiched between them. The first electrode plate 1 covers the entire back surface of the transparent glass substrate 4.
1000~ as a transparent insulating film with excellent etching resistance properties
A S nO 2 film 5 of 2000× was formed by the magnetron DC snow and vine method and was used as the starting substrate for all of the samples.

On this substrate, a dirt electrode 6 made of an At film is formed,
(2) After forming the capacitor electrode 7 of the TO film, a CVD-S 102 film 8, which becomes a dirt insulating film, is entirely formed on the entire surface. Since the dirt electrode 6 is provided in common to each pixel in one direction and serves as an address line, it is necessary to take it out to the outside at its end. For this purpose, a contact hole (not shown) is made by etching the 1CVD-8102 film 8 with perfluorinated ammonium. After this, an amorphous silicon film 9 is deposited and left on the dirt electrode 6.
Let's turn. Further, a display pixel electrode 10f is formed by vapor deposition and gloss turning of an ITO film. After this, At
After the film is deposited and the electrodes are deposited, a source electrode 12 that partially overlaps the display pixel electrode 10 and a drain electrode 1 that is commonly connected in a direction orthogonal to the address line and constitute a data line are formed. do. And the entire surface k CVD-8iOz film 1
3) This is then selectively etched with perfluorinated ammonium to form contact holes (not shown) for each terminal portion of data lines and address lines and display pixel electrodes 10.
Form the upper window. After that, the entire MO film is vapor-deposited and patterned to completely form the photoresistance film 14 in the TPT region, and the CVD-3102 film 15 is deposited again on the entire surface, and this is covered with ammonium fluoride on the contact hole and the display pixel electrode. form a window.

The second electrode plate 2 is made of ITO on the entire surface of the transparent glass substrate 16.
A film 17 is formed thereon.

The thus obtained transmission type liquid crystal display device had no clouding of the substrate and was able to exhibit good display characteristics.

By the way, the light transmittance of the first electrode plate 1 is about 80%, which is almost the same as before the TFT array assembly Ht process, and compared to when a conventional glass substrate is used as it is. It was confirmed that the transmittance was more than twice as high.

In addition, as a result of all experiments in which a 5nO7 film formed on a borosilicate glass substrate was immersed in hydrochloric acid, aqua regia, phosphoric acid, hydrofluoric acid, and ammonium fluoride for 10 minutes, the light transmittance was almost the same in all cases. It was confirmed that there was no change.

The present invention is not limited to the above embodiments. For example, the glass substrate f on which the TFT array is integrated: In addition to the 5n02 film, a cylindrical material with excellent acid resistance and alkali resistance and light transmittance, such as At205 and St 3N, can be used as the transparent insulating film.
4. A laminated film of SiC, etc., or a suitable combination of all these can be used.

Further, in the embodiment, the transparent insulating film was provided only on the back surface of the glass substrate, but it may be provided on both surfaces.

Furthermore, other semiconductor materials such as polycrystalline silicon can be used as the semiconductor material constituting TPT'.

[Brief explanation of the drawing]

The figure is a cross-sectional view of one pixel portion of a liquid crystal display device according to an embodiment of the present invention. 1... first electrode plate, 2... second electrode plate, 3...
...Liquid crystal, 4...Transparent glass substrate, 5...5n02
Film (transparent insulating film), 6... Dirt electrode, 7... Capacitor electrode, 8... CVD-8i02 film, 9... Amorphous silicon layer, 10... Display pixel electrode, 11
...Drain electrode, 12-7-, Z electrode, 13-=
CVD-8IO2 film, 14... light shielding film, 15.
...CVD-S i O2 film, 16... Transparent glass substrate, 17... ITO film.

Claims (1)

[Claims] A first electrode plate formed by integrally forming a thin film transistor array and display pixel electrodes selectively driven by the thin film transistor array on the surface of a transparent glass substrate, and a second electrode formed by forming a transparent conductive film on the surface of the transparent glass substrate. Board and these first. A transmissive liquid crystal display device characterized in that both surfaces or the back surface of the sandwiched between the second electrode plates are coated with a transparent insulating film having excellent etching resistance.