JP2954114B2 - Manufacturing method of liquid crystal display device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission type active matrix type liquid crystal display device manufacturing method.

[0002]

2. Description of the Related Art In recent years, as a display element using a liquid crystal, a large-capacity, high-density active matrix type liquid crystal display element for a television display, a graphic display or the like has been developed and put into practical use. In such a display element, high-contrast display without crosstalk can be performed.
A semiconductor switch is used as a means for driving and controlling each pixel. As the semiconductor switch, a TFT or the like formed on a transparent insulating substrate is usually used because a transmissive display is possible and the area can be easily increased.

FIG. 4 is a sectional view showing one pixel of a liquid crystal display device using a display pixel electrode array provided with a TFT. In FIG. 1, a thin film transistor (Thin Film Transistor) including a gate electrode 2, a gate insulating film 3, a semiconductor layer 4 made of amorphous silicon (α-Si), a drain electrode 5 and a source electrode 6 is provided on a first substrate 1. , TF
T) 7 and a pixel electrode 8 connected to the source electrode 6 of the TFT 7, and a protective film 9 is formed so as to cover the TFT 7 and the pixel electrode 8. On the second substrate, a light-shielding layer 11 is formed at a predetermined position, and a counter electrode 12 is formed on the entire surface so as to cover the light-shielding layer 11. The liquid crystal layer 13 is sandwiched between the first and second substrates 1 and 10 to form a liquid crystal display element 14. Further, a backlight 15 is provided behind the second substrate 10 and the display is observed from the first substrate 1 side. Here, the light-shielding layer 11 has a role of covering an electrodeless portion at a boundary between pixels and a role of preventing characteristics of the TFT 7, particularly, off characteristics from being changed by light from the backlight 15 or ambient external light. ing.

FIG. 5 is a sectional view showing one pixel of a liquid crystal display device using a display pixel electrode array provided with a TFT similarly to FIG. 4, and portions corresponding to FIG. 4 are denoted by the same reference numerals. . FIG. 5 differs from FIG. 4 in that a backlight 15 is provided behind the first substrate 1.

In these liquid crystal display devices, the gate electrode 2
When a write pulse is applied to the liquid crystal layer 13, the state of conduction between the drain electrode 5 and the source electrode 6 is established, and the signal of the drain electrode 5 is interposed between the pixel electrode 8 and the counter electrode 12.
The signal is stored in the capacity of Thus, the pixel is in an operation state, and a signal is written to the pixel. From the fall of the write pulse to the next write pulse being applied, the liquid crystal layer 13 is in the holding state,
The operation of the liquid crystal display element is held by the capacitance of. At this time, the region between the drain electrode 5 and the source electrode 6 is ideally in a non-conducting normal state. However, since α-Si constituting the semiconductor layer 4 of the TFT 7 has photoconductivity, external light is Then, the drain electrode 5 and the source electrode 6 do not become completely non-conductive, and the potential of the pixel electrode 8 gradually approaches the potential of the drain electrode 5. Therefore, even in the holding state, the signal potential is constantly affected, and a phenomenon called so-called crosstalk causes a reduction in display contrast or causes uneven brightness in a screen.

In order to prevent external light from entering the TFT 7, a light shielding layer 11 as shown in FIG. 4 is generally provided. As the material of the light-shielding layer 11, there are roughly two types of materials, a dyeing material and a metal film. However, since the dyeing material has a disadvantage of lacking fine workability, a metal film is often used.

[0007]

However, when a metal film is used as the material of the light shielding layer 11, in the arrangement shown in FIG. 4, external light from the display observation surface is reflected by the light shielding layer 11, and the reflected light Affects the semiconductor layer 4 of the TFT 7. Further, in the arrangement shown in FIG. 5, external light from the surroundings may be reflected on the display surface and affected on the display. In this case, the leakage current passing through the TFT 7 during the holding operation becomes large, causing uneven brightness at the top and bottom of the screen, crosstalk, and flickering of the screen. The present invention has been made in view of such circumstances.

[0008]

According to the present invention, there is provided a method of manufacturing a liquid crystal display device, comprising: a pair of substrates; a liquid crystal sandwiched in a gap obtained by combining one main surface of the pair of substrates so as to face each other; A method of manufacturing a liquid crystal display device having a light shielding layer disposed between substrates, comprising: forming a metal oxide film, a laminated film having a metal film; and forming a light shielding layer by patterning the laminated film. , Is characterized by having.

The liquid crystal display device manufactured by the method of manufacturing a liquid crystal display device of the present invention is provided with a light-shielding layer such that a metal oxide film is disposed on the display observation surface side, so that external light from the display observation surface side can be obtained. On the other hand, the metal oxide film becomes an anti-reflection film, and the reflectance is reduced.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of the present invention will be described in detail with reference to the drawings. In FIG. 1, a gate electrode 2 is formed on one main surface of a first substrate 1 made of, for example, glass by coating a Cr film, for example, by a sputtering method and then performing photo-etching in a predetermined shape. A gate insulating film 3 made of, for example, SiOx is formed so as to cover this by a plasma CVD method. The portion of the gate insulating film 3 facing the gate electrode 2 is, for example, an i-type hydrogenated amorphous silicon (α-S
A semiconductor layer 4 of i: H) is formed using a plasma CVD method. Then, on the gate insulating film 3 adjacent to the source region side of the semiconductor layer 4, for example, an ITO (indium tin oxide) film is coated by a sputtering method, and then the pixel electrode 8 is formed by photo-etching into a predetermined shape. Is provided. One end of the source electrode 6 is connected to the source region, and the other end of the source electrode 6 is connected to the pixel electrode 8 so as to extend therefrom. Further, a drain electrode 5 and a source electrode 6 are provided in the drain region, for example, M
After the o film and the Al film are sequentially coated by the sputtering method, they are formed by the same process of photoetching into a predetermined shape. In this way, a predetermined thin film element 7, that is, a TFT, and a pixel electrode 8 connected thereto are obtained on the first substrate 1. Here, one pixel is constituted by the thin film element 7 and the pixel electrode 8 connected thereto. Although not shown, the one pixel is arranged in a matrix on the first substrate 1. Further, on one main surface of the first substrate 1, a protective film 9 made of, for example, SiOx is formed on the entire surface.

On the other hand, a second substrate 10 made of, for example, glass
A counter electrode 12 made of, for example, ITO,
In addition, a light shielding layer 11 as a black matrix having a predetermined opening corresponding to the pixel electrode 8 is sequentially formed. Here, the light shielding layer 11 is formed as shown in FIG.
It has a two-layer structure of a metal oxide film 11a made of, for example, chromium oxide / a metal film 11b made of, for example, chromium. In the light shielding layer 11, the metal oxide film 11a is the layer closest to the second substrate side. The thickness of the metal film 11b is about 1000 angstroms, while the thickness of the metal oxide film 11a is several tens of angstroms.
Is so thin that it can be ignored. The light-shielding layer 11 is formed by first forming a chromium layer having a thickness of several tens of angstroms and then performing an oxidizing process by an anodic oxidation method or the like to form a metal oxide film. About 1000
A chromium layer of angstrom may be formed to form a metal film, and then patterned into a predetermined shape. The first and second substrates 1 and 10 are combined so that one main surface side is different from the first and second substrates 1 and 10, and a liquid crystal layer 13 is sandwiched in a gap obtained by the combination. Thus, a desired active matrix type liquid crystal display element 14 is obtained.

Further, on the first substrate 1 side, an illuminating means 15 composed of, for example, a cold-cathode discharge tube is arranged so that illumination is performed from the other main surface side of the first substrate 1. In this embodiment, a metal oxide film 11 as an anti-reflection film is applied to external light incident from the second substrate 10 side serving as a display observation surface.
Due to the presence of a, the reflectance is reduced, and the visibility of the display due to the decrease in contrast is not felt.

A liquid crystal display device according to still another embodiment is shown in FIG.
As shown in the figure, the structure of the light-shielding layer includes a three-layer structure of the metal oxide film 11a / metal film 11b / metal oxide film 11c, and the uppermost layer and the lowermost layer are metal oxide films.

FIG. 2 shows the signal voltage (V) and transmittance (%) when the light shielding layer 11 has a three-layer structure as shown in FIG. 1 and a two-layer structure as in FIG. FIG. As can be seen from FIG. 2, the configuration of the light shielding layer 11 is the metal oxide film 11a / metal film 11b / metal oxide film 1
By using the three-layer structure 1c, the signal voltage at which the transmittance becomes 50% can be reduced by 100 to 300 mV as compared with the two-layer structure of FIG. 3C. this is,
The addition of the metal oxide film 11c allows the liquid crystal display element 1
It is considered that the light reflected on the light shielding layer 11 inside 4 decreased. With such a three-layer structure, a better effect can be obtained as compared with the case of a two-layer structure. In this embodiment, even when the backlight, which is the illuminating means, is installed on either substrate side, good image quality can be obtained without being affected by external light from the observation surface side.

[0015]

By arranging the liquid crystal display device manufactured according to the present invention so that the metal oxide film of the light-shielding layer is on the display observation surface side, the light-shielding layer for external light incident from the display observation surface side is provided. By reducing the reflectance, a decrease in contrast can be reduced and good image quality can be obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a liquid crystal display device that supports one embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between signal voltage and transmittance of a liquid crystal display element.

FIG. 3 is an enlarged cross-sectional view of a light shielding layer.

FIG. 4 is a cross-sectional view illustrating an example of a conventional liquid crystal display device.

FIG. 5 is a cross-sectional view illustrating an example of a conventional liquid crystal display device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... 1st substrate 7 ... Thin film element 8 ... Pixel electrode 10 ... 2nd substrate 11 ... Light shielding layer 11a ... Metal oxide film 11b ... Metal film 11c ... Metal oxide film 12 ... Counter electrode 13 ... Liquid crystal layer 14 ... Liquid crystal display element 15 ... lighting means

Claims (2)

(57) [Claims] 1. A thin film element on one principal surface and a thin film element connected to the thin film element
One pixel consisting of pixel electrodes
One substrate, corresponding to the counter electrode and the pixel electrode on one main surface
Substrate on which a light shielding film having a predetermined opening is formed
And the first principal surface of the first and second substrates oppose each other.
Liquid crystal sandwiched in the gap obtained by combining
In the method for manufacturing a liquid crystal display device having a metal oxide film on the second substrate,
A method for manufacturing a liquid crystal display device, comprising: a step of sequentially forming a metal film to form a laminated film ; and a step of patterning the laminated film to form the light-shielding layer. 2. The step of forming a laminated film includes forming a metal film on a substrate and oxidizing the metal film to form a first metal oxide film; and forming a metal film on the first metal oxide film. 2. The method according to claim 1, further comprising: laminating a film.