JPS63195687A - Terminal construction of active matrix substrate - 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 [Field of Industrial Application] The present invention relates to a terminal structure of an external signal input terminal formed in the peripheral portion of an active matrix substrate using MIM elements as active elements.

[Conventional technology]

An active matrix substrate is a constituent substrate of an active matrix type liquid crystal panel that can achieve high image quality, and is a component substrate of an active matrix type liquid crystal panel that can achieve high image quality.
It is a device in which IM elements etc. are formed in a matrix on a transparent substrate - as an active element, compared to TFT, M
IM elements have a simpler structure, shorter manufacturing processes, and higher yields, making them more cost-effective and suitable for larger screens.
The figure shows an equivalent circuit diagram of a panel constructed from an active matrix substrate using MIM elements.
This is a terminal for inputting a drive signal to the MIM element connected in the direction of the K-chuck semi-spring knife. Reference numeral 3 denotes an external terminal of a striped electrode pattern formed on a glass substrate facing the MIM substrate with a liquid crystal in between, and is usually formed of a transparent conductive film such as TO. 4 is an MIM element, and 5 is a liquid crystal layer. MIM elements have voltage-current characteristics similar to diode characteristics, so depending on the voltage applied to external terminals 2 and 3, a signal may be written to a certain pixel or no signal may be written to a certain pixel. or

FIG. 2 is a pattern diagram of the MIM board.

In the figure, 6 is a glass substrate, 7 is a pattern made of a first metal film, and 8 is a pattern made of a second metal film. Reference numeral 9 denotes a pattern made of a transparent electrode such as TO, which serves as a liquid crystal drive electrode for a pixel. The intersection point 10 between the - metal pattern and the second gold IS pattern becomes the MIM element.

The manufacturing process of the MIM element substrate will be briefly explained as follows.

First, a Ta thin film is formed and patterned on the surface of the glass substrate 60 (7 and 11 in Figure C), and then the surface of the Ta pattern is anodized to form a zero-order Or thin film to form a TIL oxide film. After forming the TO thin film that will become the zero-order liquid crystal drive electrode (8 in the figure), patterning it into a predetermined pattern allows the MIM elements to be formed in a matrix with the pattern shown in Figure 2. 11
This part is an external terminal part where the MIM element is read directly in the row direction.
12 in the figure is a pattern for removing the Ta oxide film on the terminal.

FIG. 3 is a cross-sectional view of the panel peripheral mounting structure when inputting external signals to this MIM panel terminal section 11. In FIG. 0, 6 is a glass substrate, 13 is a Ta thin film pattern, and 14 is a T
& It is a molten film. As an example, this mounting will be explained using a mounting method using an anisotropic conductive sheet 17. 15 in Figure 1 is a 7 lexiple tape such as polyimide tape, and 16
is the lead wire on the tape. An anisotropic conductive sheet 17 is placed between the lead wire and the Ta terminal portion on the MIM board.
Conductivity can be established by heat-pressing the two. This implementation method was structurally simple and was expected to be sufficiently reliable, but a major reliability problem arose.

[Problem that the invention seeks to solve]

That is, in the mounting structure shown in FIG.
The resistance between the a terminals increases and after a certain time, the withstand voltage is reached.This phenomenon is caused by oxygen in the atmosphere diffusing in the anisotropic conductive film and causing IllI on the surface of 76.
The present invention was invented in order to solve such a fatal problem.

[Means for solving problems]

This problem, as mentioned above, is a phenomenon that occurs due to the formation of a Ta oxide film on the surface of Test 3 [Airborne acid only. Therefore, it is necessary to cover the surface of the Ta metal grain with a film that is resistant to oxidation. It is also possible to use a thin film of gold, etc., but the process would be longer. - As mentioned above, in the case of MIM substrates, which have a small number of MIMs, a TO thin film is used as the liquid crystal drive electrode, so it can be formed in the same process. We investigated a structure in which a Ta metal surface is covered with a TOAI film.

〔Example〕

FIG. 4 is a pattern diagram explaining the pattern of the terminal structure of the active matrix substrate according to the present invention. 18 in FIG. 0 is a liquid crystal driving i! The electrode pattern is an x'rO pattern formed in the same process, and is formed in two layers on the Ta terminal.

FIG. 5 shows a cross section and a plan view. In FIG. 5 (α), 6 is a glass substrate, 13 is a terminal portion made of Ta, and 14 is a Ta oxide film. '! of the terminal section! 'a After removing the oxide film,
Form a TO thin film as shown in 8,
1-T'Fn/T'*increase"!,"5)-1-su-,=y
Figure 5Cb) shows a panel mounting structure using im construction.We conducted high-temperature operation and humidity resistance tests on this structure in the same manner as before, and examined the changes in contact resistance at the connection parts. It was at a level that caused no problems.

〔Effect of the invention〕

FIG. 6 is a diagram showing an example of a change in contact resistance over time. These are the results of a humidity resistance test at 60°C and 90%. The vertical axis shows the change over time, with the initial value of the contact resistance being 1. For those with only Ta terminals, the resistance gradually increases and 2
0 to 10011 [later, it has a withstand voltage of several VIQ degrees, whereas the two-layer structure with terminals made of T O/Ta has almost no change in resistance.

As explained above, the present invention uses a transparent substrate mainly as a terminal structure of an active matrix substrate for an active panel in which MIM elements are formed in a matrix, on a gold film of MIM elements connected in the row or column direction. By adopting a two-layer structure of overlapping transparent conductive films for liquid crystal drive electrodes, we have established an extremely reliable mounting method. Of course, this invention provides a terminal structure that can be applied to other types of active matrix elements. Needless to say, it can be applied.

In addition, although the embodiment described a mounting method using an anisotropic conductive film, the double-layer structure terminal according to the present invention is very effective even in other mounting methods where oxidation of the Ta terminal surface is a problem. be.

[Brief explanation of the drawing]

Fig. 1 is an equivalent circuit diagram of an active matrix panel using nonlinear elements MIM, Fig. 2 is a pattern diagram of an M-V active matrix board, and Fig. 3 is a conventional M
A mounting structure diagram of peripheral terminals of the IM panel. FIG. 4 is an explanatory diagram of a two-layer structure pattern of TO/Ta according to the present invention;
FIG. 5 is a diagram of a mounting structure employing the terminal structure of an active matrix board according to the present invention, and FIG. 6 is a data diagram comparing the change in contact resistance over time between a conventional terminal structure and a terminal structure of the present invention. Applicant: Seiko Epson Corporation (b) Figure 14 (a) (b) Figure 5

Claims (2)

[Claims] (1) A pixel circuit consisting of an MIM (metal film-insulating film-metal film) element and a transparent drive electrode connected to one of the metal films is formed in a matrix on a transparent substrate, and the other metal film is As a terminal structure of an active matrix substrate in which films are connected to each other in the row or column direction, a two-layer thin film for the transparent drive electrode is formed on the terminal end of a metal film that is connected to each other in the row or column direction. A terminal structure of an active matrix board, characterized in that: (2) As a terminal structure, IT is placed on the Ta (tantalum) film.
The terminal structure of an active matrix substrate according to claim 1, characterized in that it has a two-layer structure in which an O (indium-tin oxide) film is formed.