JPH0527258A - Production of active matrix substrate - Google Patents

Abstract

PURPOSE:To inspect an image display device without disassembling it before the image display device which enables correction is assembled and to perform a rubbing process without any trouble. CONSTITUTION:Before the inspection, gate bus lines 3 and source bus lines 5 are wired in a lattice shape, picture elements which have thin film transistors 2 and picture element capacitances 1 are arranged in a matrix in areas encircled with the gate bus lines 3 and source bus lines 5, and external terminals 12 are formed. After the inspection and before the rubbing process, a short-ring conductor 6 which short-circuits the gate bus lines 3, source bus lines 5, and external connection terminals 12 is formed. Consequently, neither the formation of the short-ring conductor 6 nor the assembly of the image display device is performed before the inspection. Therefore, the image display device need not be disassembled at the time of corrections and the inspection is performed without any trouble. Further, the short-ring conductor 6 is formed after the inspection, so the rubbing process can be performed without trouble.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an active matrix substrate mainly used for an image display device such as a liquid crystal display.

[0002]

2. Description of the Related Art As the above active matrix substrate, the one shown in FIG. 5 is conventionally known. That is, the gate bus lines 103 and the source bus lines 105 are wired in a grid pattern on the substrate 107, and both lines 103, 10
A pixel capacitance 1 for accumulating charges in the area surrounded by 5.
01 and thin film transistors 102 are arranged in a matrix. A capacitance wiring 104 is connected to one electrode of the pixel capacitance 101, and one end of each capacitance wiring 104 is grounded via a common line 104a.

The gate bus line 103 is connected to the gate electrode of each thin film transistor 102, and controls the switching operation of the thin film transistor 102 based on a signal given from an external connection terminal 112 connected to one end. On the other hand, the source bus line 105 is connected to each thin film transistor 10
An image signal to be displayed, which is connected to one of the two source electrodes and is connected to one end of the external connection terminal 112, is written in each pixel. This operation will be described in detail. When a plurality of gate bus lines 103 sequentially output an ON signal to the thin film transistors 102, one row of thin film transistors arranged side by side is regarded as one group and each group is turned on from top to bottom. Then, during the ON state, electric charges according to the image signal sent through each source bus line 105 are written in each pixel capacitor 101.

FIG. 6 shows a structure of an active matrix substrate formed by using a top gate type thin film transistor (hereinafter abbreviated as TFT) as the thin film transistor. This substrate is manufactured as follows. First, a silicon thin film 122 to be an electrode for a channel of a TFT and an electrode for a pixel capacitance is formed on a transparent insulating substrate 121, and a gate insulating film 123 and a part of the polycrystalline silicon with a gate electrode 124 formed thereon. The film is formed in this order. Impurities are doped into necessary portions of the silicon thin film 122 by an ion implantation method or the like, and then an interlayer insulating film 125 is formed.

Next, a contact hole penetrating the interlayer insulating film 125 and the gate insulating film 123 is opened, and an AlSi layer 126 is formed on the interlayer insulating film 125 with a part thereof inserted in the contact hole. In this case, the portion of the AlSi layer 126 on the left side of the gate electrode 124 corresponds to the source bus line 105 described above. Furthermore,
A second interlayer insulating film 127 is formed on the substrate 121, a contact hole is formed in the second interlayer insulating film 127, and then a pixel electrode 128 made of ITO is formed on the second interlayer insulating film 127. To do.

By disposing a transparent insulating substrate having a transparent electrode formed on the surface thereof so as to face the active matrix substrate manufactured in this manner, and a liquid crystal is sandwiched between both substrates. , A liquid crystal display for displaying information corresponding to the image signal given to the picture element electrode 128.

By the way, the inspection of the active matrix substrate is performed up to the state of the liquid crystal display (image display device), and all the pixel electrodes are exposed to the liquid crystal display.
Alternatively, a defective portion where desired display is not performed is optically detected by applying a dark electric signal. But,
According to this optical inspection, even if the active matrix substrate is defective, it cannot be inspected unless the steps for assembling the image display device are performed. On the other hand, even if a defect can be detected, the image display device is disassembled. It has to be reassembled after the modification, which increases the cost and lowers the workability.

Therefore, before assembling the image display device,
A method for electrically inspecting an active matrix substrate has been proposed (for example, JP-A-64-9375). This method writes a signal to each pixel capacitance through a TFT,
This is a method of reading it out after a certain period of time, and utilizes the electrical action of the pixel capacitance. Note that the written signal can be read again
The inspection can be performed only when the time constant during writing of the TFT is sufficiently small and the time constant during holding is sufficiently large.

Therefore, when there is some failure in the writing or holding operation, a signal different from the signal read from the normal portion is read. Therefore, in the above electrical inspection, it is possible to determine whether or not the picture element is defective based on the read signal. Further, according to this electrical inspection method, since the inspection is performed for each picture element, the location of the defective picture element can be specified, and thus the defective location can be corrected without making a mistake.

[0010]

Among the active matrix substrates that have been electrically inspected as described above, those that have been determined as non-defective and those that have been modified are image displays that sandwich a display medium such as liquid crystal. Sent to the process of making the device,
A rubbing process for orienting the display medium is performed.
However, since this treatment is performed by rubbing the alignment film made of polyimide or the like formed on the substrate with a cloth, a large amount of static electricity is generated, which causes a problem that the TFT is destroyed and becomes defective.

In order to prevent the destruction of the TFT,
The external connection terminal 112 connected to the TFT 102, the gate bus line 103, and the source bus line 105 are electrically connected by a wiring called a short ring to make a short circuit, and a rubbing process is performed in that state, and the short ring is performed after the rubbing process. A method of cutting the wiring is known. However, when this method is adopted, there is a problem that the above-described electrical inspection method cannot be used because all bus lines are short-circuited.

The present invention has been made to solve the above-mentioned problems of the prior art, and can be inspected before assembling into an image display device so that the image display device can be corrected without disassembling and rubbing can be performed. It is an object of the present invention to provide a method for manufacturing an active matrix substrate that can be processed without any trouble.

[0013]

A method of manufacturing an active matrix substrate according to the present invention comprises a method of arranging scanning lines and signal lines in a grid pattern, and switching elements and picture elements in a region surrounded by the scanning lines and signal lines. A step of arranging each picture element having a capacitance in a matrix and forming an external connection terminal; a step of electrically inspecting the operation of each picture element; the scanning line, the signal line, and the The step of forming a short ring wiring for short-circuiting the external connection terminals and then performing a rubbing treatment is included, whereby the above object can be achieved.

[0014]

According to the method of the present invention, the short ring wiring for short-circuiting the scanning line, the signal line and the external connection terminal is formed after the inspection and before the rubbing process. The display device has not been assembled yet. Therefore, it is not necessary to disassemble the image display device for correction, and the inspection can be performed without any trouble.
Further, since the short ring wiring is formed on the active matrix substrate after the inspection, the rubbing process can be performed without any trouble.

[0015]

FIG. 1 is an equivalent circuit diagram showing an example of an active matrix substrate manufactured by the method of the present invention, showing a state after inspection and before rubbing treatment. A gate bus line 3 and a source bus line 5 are wired in a grid pattern on a substrate 7, and a picture having a picture element capacitor 1 for accumulating charges and a TFT 2 is provided in a region surrounded by both the lines 3 and 5. The elements are arranged in a matrix. The capacitance wiring 4 is connected to one electrode of the pixel capacitance 1, and one end of each capacitance wiring 4 has a common line 4
It is grounded via a.

The gate bus line 3 is connected to the gate electrode of each TFT 2, and controls the switching operation of the TFT 2 based on a signal given from an external connection terminal 12 connected to one end (left end). On the other hand, the source bus line 5 has T
An image signal to be displayed, which is connected to the source electrode of FT2 and is supplied from the external connection terminal 12 connected to one end, is written in each pixel.

All the other ends (right ends) of the gate bus lines 3, all the other ends (upper ends) of the source bus lines 5, and one end (upper ends) of the common lines 4a are connected to the short ring wiring 6. There is. The short ring wiring 6 is formed after performing an electrical inspection described later.

FIG. 2 shows a sectional structure of the active matrix substrate. This active matrix substrate is manufactured as follows. First, the transparent insulating substrate 21
A silicon thin film 22 to be a channel electrode of the TFT 2 and one electrode of the pixel capacitor 1 is formed on the gate insulating film 23, and a part thereof is a gate electrode 24, and the other part is the pixel capacitor. A polycrystalline silicon film serving as the other electrode 24b of No. 1 is formed in this order. Impurities are doped into necessary portions of the silicon thin film 22 by an ion implantation method or the like, and then an interlayer insulating film 25 is formed.

Next, a contact hole penetrating the interlayer insulating film 25 and the gate insulating film 23 is opened, and the interlayer insulating film 25 is partially inserted in the contact hole.
An AlSi layer 26 is formed on top. In this case, the portion of the AlSi layer 26 on the left side of the gate electrode 24 corresponds to the source bus line 5 described above. Furthermore, such a substrate 2
A second interlayer insulating film 27 was formed on top of No. 1 and a contact hole was formed in this film.

In this state, electrical inspection is performed. That is,
A signal is written to each pixel capacitor 1 through the TFT 2, and after a certain period of time, it is read and inspected. Above picture element capacity 1
Is formed at the portion where the electrode 24b and the silicon thin film 22 face each other.

When the above-mentioned inspection is completed, an ITO film is formed on the second interlayer insulating film 27 by inserting a part of the contact hole formed in the film into an ITO film, and patterning the ITO film. Elementary electrode 28 and the short ring wiring 6
To form. The short ring wiring 6 is formed, for example, as shown in FIG. The short ring wiring 6 was provided by penetrating the portion of the second interlayer insulating film 27 existing on the end portion of the source bus line 5 to open a contact hole 27a and forming an ITO film thereon.

Then, an alignment film (not shown) was formed on almost the entire surface of the substrate 21 on which the short ring wiring 6 was formed, and the alignment film was rubbed by rubbing with a cloth or the like. At this time, the gate bus line 3, the source bus line 5, the external connection terminal 12, and the capacitance wiring 4
However, since it is short-circuited via the already formed short ring wiring 6, a large static electricity is not generated during the rubbing process, and the TFT 2 is not destroyed.

After that, the vicinity of the connection portion of the gate bus line 3 with the short ring wiring 6 is cut, and similarly, the vicinity of the connection portion of the source bus line 5 and the common line 4a with the short ring wiring 6 is cut. As a result, the active matrix substrate of this example is manufactured. The disconnection is performed by the gate bus line 3, the source bus line 5 and the common line 4a.
The connection points of the short ring wiring 6 connected to each other may be cut off.

Next, a liquid crystal display is manufactured by facing a transparent insulating substrate having a transparent electrode formed on a surface separately prepared to the active matrix substrate and sandwiching liquid crystal between the two substrates.

Therefore, according to the method of the present invention,
Before the inspection, the formation of the short ring wiring 6 and the assembling into the liquid crystal display have not been performed yet. Therefore, it is not necessary to disassemble the liquid crystal display at the time of correction, and the inspection can be performed without any trouble. Further, since the short ring wiring 6 is formed on the active matrix substrate after the inspection, it is possible to suppress the occurrence of a defect caused by static electricity that occurs when the rubbing process is performed.

In the above embodiment, the short ring wiring 6
Is formed by ITO in the same step as the pixel electrode 28, because the manufacturing process can be simplified as compared with the case where they are formed separately. However, the operation test of the active matrix substrate can be performed when the TFT, the capacitor, the gate and the source bus line of each picture element are formed, so that another metal or the like is used after the picture element electrode 28 is formed. Short ring wiring may be formed. Even when the short ring wiring is formed at the same time as the picture element electrode, the short ring wiring may be formed using a material different from that of the picture element electrode.

In the above embodiment, the second interlayer insulating film 27 was formed and the inspection was performed after opening the contact hole that penetrates the second interlayer insulating film 27. The inspection time is AlSi.
It may be performed after forming the layer 26.

In the above embodiment, the top gate type T
Although the active matrix substrate including the FT has been described, the present invention is not limited to this, and it is needless to say that the present invention can be applied to an active matrix substrate including a TFT having a bottom gate structure.

Further, the present invention can be applied to the active matrix substrate of the equivalent circuit diagram shown in FIG. This active matrix substrate contains a gate drive circuit 30 and a source drive circuit 31, and one end (left end) of each gate bus line 3 is connected to the gate drive circuit 30.
The gate drive circuit 30 has an X start, an X clock,
External connection terminals 32a, 32b, 32 for V _DD and GND
c, 32d.

One end (lower end) side of the source bus line 5 is extended, the other end of the source bus line additional capacitance 8 having one end connected to the capacitance wiring 4 is connected in the middle thereof, and an analog switch is provided at a position further closer to the end. 9 is interposed, and the source drive circuit 31 is connected to one switch terminal of the analog switch 9.
Is connected, and the video external connection terminal 34 is connected to the other switch terminal. The source drive circuit 31 is
The external connection terminals 33a, 33b, 33c and 33d for Y start, Y clock, V _DD and GND are provided. Also,
Each capacitance line 4 is grounded via the common line 4a.

After the inspection, the external connection terminal 32 is
a-32d, 33a-33d, and 34 are formed, and the short ring wiring 6 is grounded. The short ring line 6 is also connected to the other end (right end) of each gate bus line 3 and the other end (upper end) of each source bus line 5.

The active matrix substrate having the drive circuits 30 and 31 built therein can be manufactured in the same manner as in the previous embodiment. That is, before forming the short ring wiring 6, the gate drive circuit 30 and the source drive circuit 3 are formed.
1 is operated to write an inspection signal from the video external connection terminal 34 to the pixel capacitor 1 through the video signal line 13, the analog switch 9 and the TFT 2, and read the inspection signal to perform the inspection.

After this inspection, an ITO film is used to form the short ring wiring 6, whereby the external connection terminal 32 is formed.
a-32d, 33a-33d, 34, the gate bus line 3, the source bus line 5, the capacitance wiring 4, and the source bus line additional capacitance 8 are all electrically short-circuited. After rubbing treatment in this state, a liquid crystal display can be manufactured.

The active matrix substrate manufactured according to the present invention can be applied not only to the above-mentioned liquid crystal display but also to image display devices in general.

[0035]

According to the method of the present invention, since the formation of the short ring wiring and the assembling into the image display device have not been carried out before the inspection, it is not necessary to disassemble the image display device for the correction, and the inspection is performed. Can be performed without any trouble.
Further, since the short ring wiring is formed on the active matrix substrate after the inspection, the rubbing process can be performed without any trouble, TFT defects are less likely to occur, and the yield can be improved.

[Brief description of drawings]

FIG. 1 is an equivalent circuit diagram showing an example of an active matrix substrate manufactured by a method of the present invention, showing a state after inspection and before rubbing treatment.

FIG. 2 is a sectional view showing the active matrix substrate.

FIG. 3 is a plan view showing a part of the short ring wiring of the active matrix substrate.

FIG. 4 is another embodiment of the present invention, showing an equivalent circuit diagram of an active matrix substrate incorporating a drive circuit.

FIG. 5 shows an equivalent circuit diagram of a conventional active matrix substrate.

6 is a cross-sectional view showing the active matrix substrate of FIG.

[Explanation of symbols]

1 picture element capacity 2 TFT 3 gate bus lines 4 capacitance wiring 4a common line 5 Source bus line 6 Short ring wiring 7 substrate 8 Source bus line additional capacity 9 analog switch 12 External connection terminal 13 video signal lines 21 board 22 Silicon layer 23 Gate insulating film 24a gate electrode 25 Interlayer insulation film 26 AlSi layer 27 Second interlayer insulating film 28 picture element electrode 30 gate drive circuit 31 Source drive circuit 32a External connection terminal 32b External connection terminal 32c External connection terminal 32d External connection terminal 33a External connection terminal 33b External connection terminal 33c External connection terminal 33d External connection terminal 34 External connection terminal

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location H01L 27/12 A 8728-4M 29/784

Claims (2)

[Claims] 1. A scanning line and a signal line are arranged in a grid pattern, and switching elements and picture elements each having a picture element capacity are arranged in a matrix in a region surrounded by the scanning line and the signal line, and an external element is provided. Forming a connection terminal, electrically inspecting the operation of each picture element, forming a short ring wiring for short-circuiting the scanning line, the signal line and the external connection terminal after the inspection, and thereafter A method of manufacturing an active matrix substrate, including a step of performing a rubbing process. 2. The method of manufacturing an active matrix substrate according to claim 1, wherein the short ring wiring is formed of the same transparent conductive film as the pixel electrodes formed in the region.