JPH02201317A - Display device - Google Patents

Abstract

PURPOSE:To obtain the device which is free from deterioration in image quality at a low cost by providing a 2nd transparent insulating substrate with a light shielding mask in the part confronting the upper part of a semiconductor layer on a 1st transparent insulating substrate. CONSTITUTION:The semiconductor layer 4 of a switching element exists on a scanning electrode 3 consisting of the opaque conductive material on the substrate and the extension part of an image element electrode 2 consisting of a transparent conductive material comes into contact with the counter substrate side of the semiconductor layer 4. The 2nd transparent insulating substrate 5 is provided with the light shielding mask 6 as well in the part confronting the upper part of the semiconductor layer 4 on the 1st transparent insulating substrate 1. The incident light from the lower part to the semiconductor layer 4 is prevented by the scanning electrode 3 consisting of the opaque conductive material on the 1st transparent insulating substrate 1 and the incident light from the upper part to the semiconductor layer 4 is prevented by the light shielding mask 6 provided on the 2nd transparent insulating substrate 5 confronted thereto. The active matrix element consists of only the scanning electrode 3, the semiconductor 4 and the image element electrode 2. The sharp images having the high contrast are obtd. in this way and the production cost is reduced.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a structure in which liquid crystal, etc. The present invention relates to a display device in which display semiconductor layers are sandwiched.

[Conventional technology]

Thin display devices such as liquid crystal displays are used in large quantities as display devices for small electronic devices such as calculators and watches.
Currently, the goal is to increase the size of the display screen and improve the image quality. An effective method for displaying high-quality images on a large screen is an active matrix method in which each pixel on the screen is provided with a switching element. Thin film transistors (T P
Three-terminal devices such as T), MIM (metal-insulating film interconnect) devices, and two-terminal nonlinear devices such as varistor three diodes have been proposed, and two-terminal nonlinear devices in particular have a simple structure. , the manufacturing cost is superior to the active matrix method using three-terminal devices. Amorphous silicon, which can be uniformly formed over a large area on a substrate such as glass, is an excellent semiconductor film for use in active matrix elements.

FIG. 2 shows a conventional active matrix type liquid crystal display device equipped with thin film diodes as switching elements.The liquid crystal display device has a structure in which a liquid crystal 8 is sandwiched between two glass substrates 1 and 5; A pixel electrode 21 and a scanning electrode 31 made of a transparent conductive film are formed on a glass substrate 7 . An active matrix element composed of a semiconductor layer 4 made of amorphous silicon or the like and a wiring electrode 51 is provided, and a counter electrode 7 made of a transparent conductive film is provided on the other glass substrate 5.
and a light-shielding mask 6 that covers the gap between each pixel. The light-shielding mask 6 has a function of preventing the contrast of the liquid crystal display from deteriorating due to light leakage from the gaps between each pixel. In the conventional liquid crystal display device shown in FIG.
Incident light 10 from the semiconductor layer 4 directly enters the semiconductor layer 4 . Semiconductor materials such as amorphous silicon used in active matrix elements almost always have photoconductivity, so when incident light 10 enters the semiconductor layer 4 as shown in FIG. 2, leakage current due to photoconductivity occurs. There is a problem in that the switching characteristics of the active matrix element are deteriorated, and the performance of the display device is reduced. In order to prevent light from entering the semiconductor layer 4, a light-shielding film may be provided below the semiconductor layer 4. A conventional example in which this light-shielding film 11 is provided is shown in FIG.

FIG. 4 (al to Tfl shows the manufacturing process of a substrate provided with an active matrix element equipped with a lower light-shielding film 11 of the liquid crystal display device shown in FIG. 3. First, a transparent conductive film 20 is formed on a glass substrate 1. The metal film 30 is stacked in Figure a), the pixel electrode 21. The scanning electrodes 31 are patterned while being covered with metal films 13 and 12 (Figure b).Next, amorphous silicon or the like deposited by plasma CVD is patterned to form a semiconductor that partially adheres to the pixel electrodes 21. Layer 4 is formed (Figure c) a. Further, a metal film is deposited and patterned to provide wiring electrodes 51 that connect semiconductor layer 4 and scanning electrodes 31 (Figure d), and then wiring electrodes 51 are formed.
The semiconductor layer 4 is re-patterned using as a mask (
Figure e), using the wiring electrode 51 and semiconductor layer 4 as a mask, the exposed portion of the metal 1113 is removed by etching, leaving the lower light shielding film 11 (Figure f).

[Problem to be solved by the invention]

As can be seen from the steps shown in FIG. 4, the manufacturing of the active matrix element having the lower light shielding film 11 shown in FIG. 3 is different from the manufacturing of the active matrix element shown in FIG. There is a problem in that the manufacturing process becomes complicated due to the increase in the number of film forming and patterning steps, resulting in a decrease in yield and, as a result, an increase in manufacturing costs.

The object of the present invention is to solve such problems and to manufacture a display device at a low cost without deteriorating the switching characteristics of the active matrix element due to leakage current caused by light entering the semiconductor layer and deterioration of the switching characteristics of the active matrix element. It is provided at a cost.

[Means to solve the problem]

In order to solve the above problems, a switching element and one pixel electrode are provided on a first transparent insulating substrate, and both sides of the semiconductor layer of the switching element are connected to the pixel electrode and the scanning electrode. In a display device in which the other pixel electrode and a light shielding mask are provided on a transparent insulating substrate, and a display semiconductor layer is present between both pixel electrodes, the semiconductor layer of the switching element is a scanning electrode made of an opaque conductive material on the substrate. A second transparent w
It is assumed that a light-shielding mask is also provided on the green substrate A in a portion facing the upper portion of the semiconductor layer on the first transparent insulating substrate.

[Effect]

In the above structure, light incident on the semiconductor layer from the bottom is prevented by the scanning electrode made of an opaque conductive material on the first transparent insulating substrate, and light incident on the semiconductor layer from the top is prevented by the scanning electrode made of an opaque conductive material on the first transparent insulating substrate. This is prevented by a light shielding mask provided on the transparent insulating substrate. Further, since the active matrix element according to the present invention has a simple structure consisting of only scan electrodes, semiconductors, and pixel electrodes, the manufacturing process is simple.

〔Example〕

FIG. 1 shows a display device according to an embodiment of the present invention, and FIG.
Components common to those in FIG. 3 are given the same reference numerals. In this display device, the pixel type f! j2 is made of a transparent conductive film, the scanning electrode 3 is made of a metal material, and the 0 pixel electrode 2, which is opaque, extends to the upper surface of the semiconductor layer 4. As a result, a switching element occurs between the scanning electrode 3 and the extension of the pixel electrode 2. The incidence of light through the glass substrate 1 on the semiconductor layer 4 of the switching element is blocked by the scanning current 1Ii3.

On the other hand, the incidence of light from the upper glass substrate 5 through the transparent pixel t8i is blocked by the light shielding mask 6 which extends above the semiconductor layer 4, unlike in FIGS. 2 and 3.

FIG. 5(5) is a plan view of the glass substrate 1 of FIG. 1 viewed from the pixel electrode 2 side. An element 41 made of the semiconductor layer 4 shown in cross section in FIG. 1 and an element 42 provided on the connection type 8i32 are connected in parallel between the pixel electrode 2 and the scanning electrode 3 via the lower connection electrode 32 and the upper connection electrode 22. Connected in reverse. The lower connection electrode 32 is formed at the same time as the scanning electrode 3 is formed by patterning, and also serves as a light shielding film for the switching element 42. The upper connection electrode 22 is made of the same transparent conductive film as the pixel electrode 2.

5) is a perspective view seen from above the glass substrate 5, and the planar pattern of the light-shielding mask 6 shows the gaps between the pixel electrodes and the gaps between the pixel electrodes and the scanning electrodes, as shown with hunting. The covering is similar to that in FIGS. 2 and 3, but the pixel electrode 2 and the lower connection electrode 22 extending above the semiconductor layer 4 are also covered. Materials used for the light-shielding mask 6 include natural polymers such as gelatin and casein, synthetic polymers such as Nippon Synthetic Rubber (trade name: JDS-509), and Nippon Kayaku (trade name: Black), for example.
dyed with black dye such as k81 or l
r,kl.

Metals, metal compounds, or metal oxides such as Mo, Ta, and Mo5iz are used.

6 fa) to fd+ show the manufacturing process of a substrate having an active matrix element as shown in FIG.

On the transparent insulating substrate 1, as the scanning electrode 3, a 1,000-layer thick layer of Cr is deposited by sputtering, and then buttered. After being deposited, it is buttered (Figure b).

Then, an ITO film having a thickness of 2,000 yen is deposited by sputtering and then patterned to form the pixel electrode 2 and its extension. Furthermore, by patterning the semiconductor layer 4 again using the pixel electrode 2 as a mask, the portion of the semiconductor layer 4 protruding from the pixel electrode 2 is removed (Figure d
), as described above, the active matrix element according to the present invention can be manufactured in a simple manufacturing process using only three film forming steps and three photomasks. The materials of the scanning electrode 3 include Cr, u, Mo+Ta,
Metal materials or metal compounds such as MO3Ig can be used. As the transparent insulating substrate, a polymer substrate can be used in addition to a glass substrate. As the material for the pixel electrode,
■In addition to TO, a SnO□ metal thin film can be used.

〔Effect of the invention〕

According to the present invention, light incident on the semiconductor layer of an active matrix element provided on one of two transparent insulating substrates sandwiching a display semiconductor layer is transmitted through an opaque scanning electrode formed at the bottom of the semiconductor layer and an opaque scanning electrode formed on the bottom of the semiconductor layer. Because the light is shielded by a light-shielding mask provided on the substrate, even if a photoconductive material such as amorphous silicon is used for the semiconductor layer, the switching characteristics of the device are less likely to deteriorate due to the incident light, resulting in a decrease in image quality. It is possible to obtain a display device that displays clear images with high contrast. In addition, since the extension of the pixel electrode is used as the electrode on the opposite side of the semiconductor layer to the substrate, the active matrix element can be easily manufactured using only three film formation steps and three photoprocessing steps, and has fewer defects. It is possible to improve yield and reduce manufacturing costs. It should be noted that since the opposing substrate is only changed from the conventional light-shielding mask pattern, there is no increase in manufacturing costs.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a display device according to an embodiment of the present invention, FIGS. 2 and 3 are sectional views of two conventional examples of the display device,
4 (al to (fl) are cross-sectional views sequentially showing the manufacturing process of the active matrix substrate of the display device shown in FIG. (4) is a top view of the lower substrate, (bl is v
FIG. 6 is a perspective plan view of the entire t2 from above, and is a sectional view sequentially showing the manufacturing process of the active matrix substrate of the display device shown in FIG. 1. 115 glass substrate, 2: pixel electrode, 3: scanning electrode, 4
: Semiconductor layer, 6: Light-shielding mask, 7: Opposing cylinders 3 Figure 1 Figure 4-1 Figure 6

Claims (1)

[Claims] (1) A switching element and one pixel electrode are provided on a first transparent insulating substrate, and both sides of a semiconductor layer of the switching element are connected to a pixel electrode and a scanning electrode. In a device including the other pixel electrode and a light-shielding mask, and a display semiconductor layer is present between both pixel electrodes, the semiconductor layer of the switching element is located on the scanning electrode made of an opaque conductive material on the substrate, and the semiconductor layer is located on the scanning electrode made of an opaque conductive material on the substrate. An extension of a pixel electrode made of a transparent conductive material is in contact with the side of the layer opposite to the substrate, and a light-shielding mask is also provided on the second transparent insulating substrate at a portion facing the top of the semiconductor layer on the first transparent insulating substrate. A display device characterized by being provided.