JPS61175623A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To decrease the number of process and to improve considerably yield by forming BTBD between a cell electrode and line electrode. CONSTITUTION:A non-linear device is the BTBD and a p-type a-Si layer 104, an i layer a-Si layer 105 and an a-Si:Ge layer 106 are successively laminated between the line electrode 103 and cell electrode 102 consisting of ITO formed on an insulating substrate 10. The ITO and two times of photolithographing stages for the a-Si part are just required to form the non-linear element. The process for production is extremely short and simple. Since the a-Si:Ge layer 106 has high conductivity and large coefft. of light absorption, said layer acts as a light shielding layer to suppress the malfunction of the BTBD.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a liquid crystal display device in which each pixel is provided with a nonlinear element, which enables multiplexing and greatly reduces the manufacturing process.

[Conventional technology]

In liquid crystal display devices, each pixel is provided with a nonlinear control device in order to realize a large display device. The conventional nonlinear control device includes a three-terminal element represented by a thin film transistor (F'J'), a varistor, a metal-insulator-metal (M),
There are two-terminal devices such as a back-to-back diode (hereinafter referred to as BTBD), which has two diodes connected in the opposite direction, and a back-to-back diode (hereinafter referred to as BTBD).

[Problem to be solved by the invention] However, in the above-mentioned conventional technology, in the case of a three-terminal element, the manufacturing process is long and difficult.
The control buttons of each layer require careful attention during the ~8 photolithography process, which poses a problem in that it is difficult to improve the yield and reduce the manufacturing cost. In the varistor and M process, the capacitance of the non-linear element is large, which causes a problem of crosstalk, which requires installation of additional capacitance and special measures for the element structure. In addition, amorphous silicon (hereinafter referred to as α-i) was used as the semiconductor layer and 9BT
Since α-Bi in BD can be formed by plasma discharge decomposition, it is possible to form a thin film over a large area at low temperatures, making it suitable as a switching element for large-sized displays using inexpensive glass as a substrate. FIG. 2 is a cross-sectional view of a pixel section including a conventional BTBD.

S-type α-Bi layer 20 serving as a common electrode on an insulating base 201
A 2iWa-8ff1 layer 203 is laminated, and a metal electrode 204 of platinum, gold, etc., which forms a shut-key junction, is provided on the upper surface of a-84 to form a nonlinear element. However, this conventional technique also has the problem that four photolithography steps are required, making it difficult to significantly reduce manufacturing costs. Therefore, the present invention is intended to solve these problems, and its purpose is to use an inexpensive glass substrate.

There are ways to reduce the manufacturing process to a large extent, thereby providing a liquid crystal display device with extremely low manufacturing costs.

Means for Solving Problems] In the semiconductor device of the present invention, the nonlinear device is a BTBD, and a layer of Vcpgα−S<layer and smα between the row electrode and the cell electrode formed on the insulating substrate -Bi layer and α-B
A: It is characterized by sequentially laminating Ga layers.

[Effect]

According to the above configuration of the present invention, it is necessary to perform the photolithography process twice for the α-8i section and the photolithography process for the α-8i section until the nonlinear element is formed. 1 construction is extremely short and simple. Furthermore, since the α-sI:Ga layer has high conductivity and a large light absorption coefficient, it acts as a light shielding layer and suppresses malfunction of the BTBD.

〔Example〕

FIG. 1 is a cross-sectional view of one pixel of a liquid crystal display device according to an embodiment of the present invention.
Cell electrode consisting of 2-layer To, row electrode consisting of 103-layer ITO, 104-layer α-84 layer (p layer) containing elements from group 1-b of the periodic table such as bromine, and 105-layer without contamination of impurities. α-Si layer (i tatami), 106 monosilane gas (Si
The α-Bi:G# alloy layer is formed by mixing H4) and germane gas (Gl-) and plasma discharge decomposition. α-Bi: The Gg layer has semimetallic properties and absorbs most of the visible needle tip, so it plays a role as a ml and light-shielding layer. Figure IE3 shows the current-voltage characteristics of this nonlinear element. The nonlinear element has a limit voltage vth, and when a voltage exceeding the limit voltage is applied to the visiting element, the visiting element becomes conductive. As shown in Figure 113, it has symmetrical switching characteristics with respect to 5Vc positive and negative voltages.

Figure 914 is a circuit diagram of a matrix liquid crystal display using BTBDK. There are 401 power-distributed data lines and 402 scanning lines.

403 liquid crystal display elements, 404 indicate BTBD'f. The liquid crystal display element and the BTBD are connected in series to form a unit pixel. The difference between the amplitude vd of the voltage pulse applied to the data line and the amplitude v8 of the voltage pulse applied to the scanning line (vd
-Vs) is the net voltage applied to the liquid crystal, and if this is lower than the limit voltage vth of the nonlinear element, no voltage is applied to the liquid crystal display element, and if the net voltage is higher than the limit voltage of the nonlinear element and the threshold voltage of the liquid crystal, the liquid crystal display element A voltage can be applied to change the optical state of the pixel's liquid crystal.

Furthermore, it is possible to operate by alternately applying positive and negative voltages, which have switching characteristics symmetrical to the positive and negative voltages of #BTBD, and it is possible to extend the life of the liquid crystal.

A method of manufacturing a liquid crystal display element according to the present invention will be explained with reference to FIG. A thin film of TO is formed on an insulating substrate 501 such as glass by a method such as sputtering. (Chapter 5-(b)
figure). Patterns of pixel electrodes and row electrodes are formed by a seven-dimensional etching process.

($5- (c) figure). Thereafter, the substrate is placed on a substrate support in a vacuum container, and the p layer α-ai, the <layer α-si, and the a-siaa layer are successively formed in the same vacuum container ($5-one-piece). figure).

Next, a-Bi:Gg was formed by a photophosphorography process.
, α-8i@ are patterned all at once to obtain a cell electrode (Figure 5-(g)).

The nonlinear element obtained in this example has sufficient switching characteristics as shown in FIG. 3, and can be used in a large-area liquid crystal display device that can be multiplexed by using the above-described driving method to produce uniform and high contrast ratio images. display was possible. In this embodiment, only two photolithography processes are required to form the pattern 1 of the switching element, and the number of photolithography processes is reduced by 3 to 4 times compared to a conventional liquid crystal display device. A significant improvement in yield can be expected. Ichitako T
Since the formation of O and the formation of the final electrode layer can be performed in the same vacuum container, and precise interface control unlike conventional TFTs is not required, an improvement in yield can be expected in this respect as well. Furthermore, this formation method α−s<, a−B′i
: Since the Ge layer can be formed at a low temperature of 200'C to 300C, inexpensive glass or the like can be used, making it suitable for producing and producing liquid crystal display devices at low cost.

〔Effect of the invention〕

As described above, according to the present invention, by forming KBTBD between the cell electrode and the row electrode, the number of steps can be reduced compared to the conventional manufacturing method of a liquid crystal display device, and as a result, the number of steps can be significantly reduced. This has the effect of improving yield and making it possible to manufacture highly reliable and inexpensive liquid crystal display devices.

[Brief explanation of drawings]

FIG. 1 is a main cross-sectional view of a pixel section of a liquid crystal display device according to the present invention. FIG. 2 is a main cross-sectional view of a pixel portion of a liquid crystal display device using a conventional BTBD nonlinear element. FIG. 3 is a diagram showing an example of current-voltage characteristics of the BTBD nonlinear element according to the present invention. FIG. 4 is a circuit diagram of a matrix-driven liquid crystal display according to the present invention. Figures 5 (b) to (8) are diagrams showing the manufacturing process of the pixel portion according to the present invention. 101, 201... Insulating substrates 102, 2
06...Cell electrode 103...Row electrode 104...α-BiCp layer) 105, 203...α-Sze (4 layers) 106
-a-s< Ga layer 107, 207...One counter electrode 108, 20
8...Counter substrate 202...α-Si(
1 layer) 204...Silver key electrode 205...Insulating thin film 401...Data line 402...Scanning line 403...Liquid crystal Display element 404... Bapuktupac diode 501
......Insulating substrate 502...T0 503...α-BiCp layer) 504...α-5iCi layer) 505...α -5ee 1st layer and above Izuhara Suwa Seikosha Co., Ltd.

Claims (4)

[Claims] (1) A liquid crystal layer is provided between electrodes arranged in a matrix, one of the opposing cell electrodes has electrical nonlinear means between a row electrode and a cell electrode, and the nonlinear means is provided between each opposing cell electrode. In a liquid crystal display device in which the optical state of the liquid crystal can be changed and driven by applying a voltage larger than the sum of the limit voltage of the means and the threshold voltage of the liquid crystal, the nonlinear means is arranged between the row electrode and the cell electrode. Periodic Table I
A liquid crystal display device comprising an amorphous silicon layer (p layer) containing an I-b group element and an amorphous silicon layer (i layer) containing no impurities, which are successively laminated. (2) The row electrodes and cell electrodes are indium tin oxide (
Claim 1 characterized in that the material is made of ITO)
The liquid crystal display device described in Section 1. (3) The liquid crystal display device according to claim 1, wherein an opaque and conductive electrode is formed on the nonlinear means. (4) The liquid crystal display device according to claim 1, wherein the opaque and conductive electrode is an amorphous material containing silicon and germanium elements as main components.