JPH03144422A - Panel for liquid crystal display - Google Patents

Abstract

PURPOSE:To realize a liquid crystal panel with a large aperture by using a black dielectric material as the passivation film of an active matrix substrate comprised of a thin film transistor and a transference conductive film, and selectively applying etching on a black dielectric film. CONSTITUTION:A gate wiring 11 of Cr and a pixel electrode 12 of ITO are formed on a first insulating substrate 10, and after that, a source wiring 16 is formed so as to be superimposed on part of a semiconductor layer, and a drain electrode 17 so as to superimposed on part of the semiconductor layer and a contact hole with Al. An SiO that is a black inorganic dielectric material is formed on a TFT substrate formed by sputtering. After that, a part except for the one set as a black matrix 18 by applying etching on the SiO is eliminated. Therefore, deviation for the wiring of a black stripe can be reduced, which increases the aperture. Thereby, it is possible to obtain the liquid crystal panel with a large aperture effectively.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a liquid crystal display panel having an active matrix substrate using thin film transistors, and more particularly to an active matrix substrate used in a transmissive liquid crystal display.

Twisted nematic (hereinafter abbreviated as TN) will be explained as a liquid crystal mode used in conventional liquid crystal display systems.

FIG. 2(A) is a perspective view schematically showing a panel section of a conventional liquid crystal display device. FIG. 2(B) shows a structural diagram of one pixel of an active matrix liquid crystal display using a gate insulated TPT. In these figures, 21 is a scanning line (gate bus), 22 is a data v
A (source electrode or drain electrode), 23 is electrically connected to the source electrode or drain electrode? The picture element electrode 24 for driving the night crystal is shown. Here, the TFT section is the section 25. In a normal transmissive type L&crystal display device, it is necessary to transmit light from a rear light source, so the picture element electrode 24 must be a transparent conductive film. 26 indicates a liquid crystal. The above elements are array side substrate 2
7, by repeating thin film formation 1 selective etching, etc. 28 is a passivation film. This passivation film 28 is formed on the signal line and TFT. - In general, TFT array substrates are passivated with an a-free insulating film such as SiNx or 5i02 to cut the DC voltage component of the electrodes inside the panel, thereby preventing deterioration of the display quality. Picture element TL
The passivation film 28 on the pole 24 is removed to lower the driving voltage of the liquid crystal. 29 is a transparent conductive film serving as a counter electrode, and 30 is a blank matrix. If the liquid crystal panel is to display color, it can be done by forming a color filter on each pixel of the opposing substrate. In such a liquid crystal panel, when the TPT is driven in accordance with an image signal and the voltage applied to the liquid crystal layer is changed, the transmittance of the liquid crystal panel changes accordingly, and an image is displayed. FIG. 2(C) shows the equivalent circuit. A pixel signal is written to the pixel electrode 24 during the ON period of the TPT by a scanning pulse applied to the scanning electrode 21,
This potential is held until the scan pulse of the next field.

The function of the blank matrix 30 is to suppress the photoconductivity of thin film transistors used as active elements by preventing light from entering from the front surface of the liquid crystal panel, or to prevent light from leaking from the back light source in areas other than the pixel electrodes. This improves the contrast. This blank matrix 30 is generally formed on a counter substrate by overlapping Cr◯ or R₂O,B color filters. Generally, when designing a TFT array, the width of the black matrix 30 is determined by the assembly accuracy of the array substrate and the counter substrate, and this value is generally larger than the mask alignment accuracy.

Problems to be Solved by the Invention If a black matrix is formed on the counter substrate using the method described above, when the size of the LCD panel increases, the alignment accuracy between the counter substrate and the array substrate will shift in the periphery of the panel due to the warping of the glass, resulting in black. Matrix loses its original function,
Additionally, the assembly precision between the upper and lower substrates is generally greater than the TFT array assembly precision. Due to the above factors, the width of the blank matrix must be greater than the width actually required for light shielding.

As a result, the transmittance of the 7& product panel is lowered more than necessary. To solve the above-mentioned problem, by forming the black matrix on the array side substrate instead of the counter substrate, it is possible to create a structure in which misalignment of the substrates does not become a problem even when the liquid crystal panel size increases.

Means for Solving the Problems The present invention uses a black dielectric as a badge hesigon film of an active matrix substrate consisting of a thin film transistor formed on a glass substrate and a transparent HF2 film, and selectively etches the black dielectric film. The black dielectric film is used as a blank matrix.

Function By adopting the above configuration, a black portion is formed on the array substrate side and used as a black matrix material, and this black dielectric film is formed of an inorganic material to have a function as a passivation film. As a result, the width of the black matrix can be made narrower than in the past, and a liquid crystal panel with a large aperture ratio can be realized.

Embodiment A first embodiment will be explained with reference to FIGS. 1(A), 1(B), and 1(C). FIG. 1(A) is a plan view of the first substrate;
Figures (B) and (C) show a-a after being assembled into a liquid crystal display device.
FIG. 2 is a sectional view taken along line bb' and viewed from the direction of the arrow.

Gate wiring 11 made of Cr on first insulating substrate 10
After forming the picture element electrode 12 made of ITO and SiNx
A gate insulating film 13 and a semiconductor layer 14 made of amorphous silicon are successively formed using a plasma CVD method. After that, the semiconductor layer and the gate disappeared! ! Contact holes 15 are formed in the layer by etching. Next, a source wiring 16 is formed so as to partially overlap the semiconductor layer, and a drain electrode 17 is formed using /l so as to partially overlap the semiconductor layer and the contact hole. SiO, which is a black inorganic dielectric material, is formed on the TPT substrate thus formed by sputtering. Thereafter, the SiO is etched to remove the portion other than the portion that will become the blank matrix 18.

On the other hand, the second glass substrate 19 has IT○ as a counter electrode.
Form 20. Thereafter, the two substrates are aligned, their peripheries are glued together, and liquid crystal 21 is injected between them to complete the liquid crystal panel.

By using the SiO formed on the first substrate, a blank matrix, which was conventionally formed on the counter substrate side, can be formed on the TFT array substrate side, and the SiO can also provide a bancivation function.

Therefore, compared to the conventional method in which a blank matrix is formed on the opposite substrate side, the deviation of the black stripe from the wiring can be suppressed to a small extent, so that the aperture ratio can be increased. As a result, we were able to create a bright panel.

It is obvious that the black dielectric film is not limited to SiO and may be made of other materials as long as it has sufficient insulation properties.

Furthermore, it is clear that forming the black dielectric film by a vacuum deposition method other than the spunter method does not violate the spirit of this patent.

Effects of the Invention According to the present invention, a liquid crystal panel with an effectively high aperture ratio can be obtained, which has great technical significance.

[Brief explanation of the drawing]

FIG. 1(A) is a plan view of a liquid crystal display device according to a first embodiment of the present invention, and FIG. 1(B) and (C) are FIG.
2(A) is a cross-sectional view taken along a-a and bb' lines and viewed from the direction of the arrows in A), and FIG. 2(A) is a perspective view schematically showing the liquid crystal panel of a conventional liquid crystal display device. , Figure 2 (B) is a cross-sectional view of the source wiring of a liquid crystal display device using conventional thin film transistors taken from the side, and Figure 2 (C) is an equivalent circuit of a TPT matrix substrate. It is a diagram. 11... Gate wiring, 12... Picture element electrode, 15... Contact hole, 16...
...Source wiring, 17...Drain NFit.

Claims (3)

[Claims] (1) Thin film transistors and electrodes in a liquid crystal display panel using an active matrix substrate consisting of a thin film transistor formed on the first substrate and a transparent conductive film in which liquid crystal is sealed between opposing first and second substrates. A liquid crystal display panel characterized in that an inorganic black dielectric is used as a passivation film, and the black dielectric is selectively etched so that part or all of the transparent conductive film is exposed. (2) Claim (1) or (2) characterized in that the black dielectric material is formed of an inorganic oxide or a nitrogen compound.
) liquid crystal display panel. (3) The liquid crystal display panel according to claim (1), wherein the black dielectric material is formed by a vacuum evaporation method.