JPS58130562A - Thin film transistor matrix substrate - Google Patents

Abstract

PURPOSE:To facilitate the repair work, in a transparent insulating substrate wherein thin film transistors are arranged at the intersections of a plurality of gate lines and data lines which cross at a right angle, by making the breakdown voltage of the gate insulating film of each transistor smaller than the insulation breakdown voltage at the crossover part of each line. CONSTITUTION:The thin film transistor 5 is connected to each crossover part 6 of the data line 1 and the gate line 2. In this constitution, when the insulation breakdown voltage of the insulation film of the crossover part 6 is relatively small, the lines 1 and 2 are shorted at the crossover part 6. This shortage results in the line fault, which is a serious problem is a liquid crystal display device. Therefore, the breakdown voltage of the gate insulating film of the thin film transistor 5 that is corrected to the crossover part 6 is made smaller than the breakdown voltage of the crossover part 6. If static electricity flows at an emergency, the breakdown is limited to one of the transistors 5 and the accident such as the line fault is decreased to zero.

Description

[Detailed Description of the Invention] Inventively, B+m) transistor (hereinafter abbreviated as TI)
(written as PT) is related to the board. Furthermore, present invention 1
This relates to the 1-temperature characteristics of a 1TF te matrix substrate.

In recent years, new displays to replace conventional CRT displays have been actively developed. Among these, liquid crystal displays are thin and can operate at low voltage and low power, so they are attracting attention as displays for personal information devices and portable information devices, as well as N1 calculators and watches, home appliances, and automobiles. A large market is expected for this display. Under these circumstances, a characteristic that will be required of liquid crystal displays in the future will be large capacity display capability. In other words, with the shift from gestatic drive to time-division drive, and the development of liquid crystal materials, it has now become possible to display horizontal scanning lines with a width of about 60 degrees. Material development has reached its limit, and it is difficult to increase the number of display scanning layers further without adopting an active matrix method.In light of this W view, recently, crystalline crystallization using an active matrix method has been developed. Development of non-exclusive bonds is actively underway.

Among active matrix methods, MOS (metal-
There are two types: one using an array tube (fluoride-semiconductor element) and the other using a TFT array. The former has a small area and a simple high-density display because the peripheral driver can be on-chip, while the latter has a large area and high V! ! The degree of display is consistent with the body design. In addition, from the viewpoint of the indicated product fiber, in the latter case, TPT
Since the play can be formed on a transparent insulating JLK board, the TN mode is possible as the liquid aS display mode, and the contrast is sharp.

FIG. 1 shows a plan view, a sectional structure diagram, and a circuit diagram of a conventional TPT active matrix S board. Figure 1 (al[T
FF Active matrix substrate picture representation - A plan view of one pixel which is a castle's S acid unit. In the picture, 1 is the data gA line, 2 is the gate signal line, and 3 is the Ijl
@Display electrode. This IIIiIg11 display electrode may be a single electrode with a transparent conductor, or may be a transparent conductive s'm electrode. 4 is a contact hole between the TFT source region and data in, and the TFT drain region and image gI.
This is a contact hole with the display electrode. 5 is TPT. 6d data line No. 18 and gate signal line cross-over/<g min. Normally, this data signal line and gate signal line are electrically separated by a thin insulation film such as an oxide film or a nitride layer. The area surrounded by points 11 in the diagram is a one pixel area. No. 18!1
(a) Moum cross section 1mtIJI41h(bztc
(in the figure) 7 is the gate oxide layer of TIFT, 8t'j
The TFT source-drain diffusion region 9 is absolutely m\i. Figure 1 (0) is -1! It is the j-element circuit itself. Such a conventional τIFT active matrix! ilK&
t'l, as shown in No. 211, the gate line and data line are connected to the outside of the 1st position, and the pad for terminal extraction is lighted at θ, and these are connected to the driver channel. The pad for bringing out the terminal 9 should be connected to at least one gate line or one data line. This TPT active matrix path*Fi
As shown in FIG. 1, since the TFT array is formed on an insulating substrate, it has the drawback of being extremely susceptible to static electricity. For example, outside of TPT active matrix substrate Ii! When static electricity enters from the terminal extraction pad of the i1 section, the static electricity destroys either the gate of the TPT or the part of the crossover between the gate line and the data line.

Since the normal voltage for the insulation is from several thousand volts to tens of thousands of volts, if the insulation is applied, it will definitely break down to these insulations, resulting in a short circuit or connection with low resistance. Therefore, in the manufacturing process of the TPT active matrix substrate, it is necessary to provide sufficient electrostatic countermeasures. It would be better if the 7iTFT active matrix 1 board could be equipped with a static circulation circuit with resistors and diode circuits, as is done in the MOBils board, but for now, the physical properties 'Static WX protection circuit'
iT IFT is difficult to form on active matrix substrates. Therefore, in the case of a TPT active matrix difference plate, if a problem occurs, it is recommended to pull it out in such a way as to destroy it in a specific location, and then repair that location later by cutting the wiring using a laser or the like. There is a need.

The present invention is a TFT active matrix based on the idea that when static electricity enters a TPT active matrix substrate that is weak against static electricity, it will be destroyed at a specific location, and this location will be repaired later. The present invention relates to a substrate, and will be explained below using specific examples.

ais s txi (&) u, T] FT7/? (B lol)
A case is shown in which the disconnection I#- of the crossover s6 between gate line 2 and data line 1 is destroyed when static electricity enters the 9x4 board. When a portion of this crossover breaks down, the breakdown voltage of the insulating film of this portion of the crossover is smaller than the breakdown voltage of the gate insulating film of the TFT 5. In this case, the gate line and data line are shorted in a part of this crossover, so Kllll
When applied to the destruction of a display body, etc., it becomes a big problem because it appears as a line defect. Therefore jllll! 3
As shown at 10 in FIG. 3(b) and IIK in FIG. 3(c), it is necessary to correct both the gate line and the data line with @t laser in this crossover St-nes. For example, as shown in Figure 3(b), the gate line t-2 places are cut with a laser, and the terminals are provided on both sides of this gate line)
The entry from the exit pad to the gate is good. However, in this case, the same gate information is applied to the terminal exit pads on both sides.
In order to enter R, two series of gate driver circuits are required. Since it is difficult to input the gate driver circuit t-2 series due to the cost η, the signal from the gate line adjacent to Fi is usually input. In this case, the matching gate lines (l111#) will display the same display, resulting in a display defect. The same ``''C exists in the case of wJ3 figure (c).

On the other hand, as shown in Fig. 4(a), a part of the crossover
If the rupture mw pressure is made larger than the rupture tIs voltage of the gate isolation film, the gate isolation will always be -1 due to the input of the electrostatic force.
4 will be destroyed. At this time, if the gate electrode and the source diffusion layer are short-circuited, a display defect (line defect) as shown in the previous P embodiment occurs. However, in this case, Figure 4 (bJ and (
As shown in c), line defects can be easily converted into point defects by cutting with the 12 and 13 partial tube laser in each □□□. In other words, the breakdown voltage of a part of the crossover is lower than the gate breakdown voltage of TPT.
If the gate insulating film is destroyed by static air entering from the outside, the gate insulating film will definitely be destroyed, and in this case it can be repaired more easily with a laser.

As explained in the above P embodiment, the present invention uses TIF'! which is weak against static electricity! 'In the active matrix S board,
By increasing the dielectric breakdown voltage of a portion of the crossover between the gate line and the data line as compared to the dielectric breakdown voltage of the gate, it can be destroyed in a single vacuum and can be easily repaired using a laser in the next case. ? ? The present invention relates to TIFT active matrix substrates and greatly contributes to improving the yield and reducing costs of TIFT active matrix substrates for liquid crystal display devices and electroluminescence display devices.

For example, as in the present invention, there are many ways to make the dielectric breakdown voltage of the crossover part larger than the gate breakdown voltage. In other words, the cross-over part of the insulation film and the TPT insulation II
In the case of s film t-1 made of colloid, the film thickness of the insulating film in a part of the crossover may be made thicker than the gate layer thickness.For example, when the gate insulating film is oNjlttooooX, -The film thickness is 1oooX or more 200
A value of about 0 to 1 o oo oX is desirable. Further, it is desirable to design the process and design the pattern so that even if the insulation film thickness of the crossover part and the gate insulating film thickness are the same, the breakdown voltage is larger in the crossover part.

For example, 810. In this case, the breakdown voltage will differ depending on the slight difference in phosphorus concentration. Also B10
．． The breakdown voltage also differs depending on the annealing 1jAwI after formation. Furthermore, the distribution is 111! itl step shape! Since the breakdown voltage varies depending on R-, sufficient care must be taken in the device design and process design of the four TIPT active matrix boards.

FIG. 5 is a cross-sectional view of a liquid crystal display device using a transparent insulating substrate and a TPT active matrix group @ 14 iH formed thereon (Tli mode (twisted nematic mode). 15 is an upper glass substrate, 16 is a Spacer, 1
7 is a liquid crystal layer, 18tlj polarizing plate, 19 is a reflection plate・
This TN mode liquid crystal display device provides a high contrast and bright display, making it ideal as a display for N1 small pocket televisions.

[Brief explanation of drawings]

8111 figure and M2 figure company's conventional 'rF? Figures 3 and 4 are circuit diagrams used to explain the structure and cell channels of the active matrix substrate, and Figure 5 is a circuit diagram used to explain the structure of the TFT active matrix substrate according to the present invention. A structural diagram of a liquid crystal display device using a matrix substrate. 1... Data line 2... Gate line 3... Liquid crystal drive electrode 4... Contact hole 5... FT 6... Crossover part 7... Gate insulating film 8... Source and drain diffusion region 9...Insulating substrate 10...Laser fusing part 11 of gate line/laser fusing part 12 of data line...Laser fusing part 13 of gate electrode of TFT...Source diffusion Laser-fused portion of electrode 14... TPT active matrix substrate 15... Upper glass plate 16... Spacer 17... Liquid crystal layer 18... Polarizing plate 19... Anti-pulling plate and above (C) 1st Figure 2 [1 Figure 3 Figure 4

Claims (1)

[Claims] ... A thin-film transistor matrix substrate in which thin-film transistors are arranged at each intersection of a gate line and a data line orthogonal thereto, and a gate insulating film of an [I#] transistor. The breakdown voltage of the gate line and the data line is
Thin film transistor matrix 1 plate, where the pressure and p are also small, t*m. 12+4-) The thin transistor matrix substrate according to claim 1 P, wherein the substrate on which the transistors are arranged is a transparent insulating substrate.