JP2618520B2 - Method for manufacturing active matrix liquid crystal display device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for manufacturing an active matrix liquid crystal display device using a liquid crystal as a display medium.

(Prior Art) Conventionally, in a display device using a liquid crystal as a display medium, two substrates having electrodes formed thereon are bonded together, and the liquid crystal is sealed between these substrates.

In recent years, along with higher definition and higher quality of liquid crystal display devices,
A switching element such as a thin film transistor (hereinafter referred to as “TFT”) is added to each pixel electrode formed on the one substrate, and a video signal is applied to the pixel electrode on the substrate via the TFT. An active matrix system for displaying an image is used. On an active matrix substrate constituting such an active matrix liquid crystal display device, an alignment film for regulating alignment of liquid crystal molecules is formed after a bus wiring, a TFT, a pixel electrode and the like are formed. This alignment film is usually subjected to an alignment treatment by rubbing.

Since the manufacturing process of a high-definition liquid crystal display device is very complicated, disconnection or short-circuit of the gate bus wiring functioning as a scanning line or the source bus wiring functioning as a signal line, and furthermore, a manufacturing defect such as a TFT operation defect occurs. It is known to be easy. When such a manufacturing defect occurs, the image quality of the display device is significantly impaired, and the yield of the display device is reduced.

Therefore, by checking for disconnection or short circuit of the gate bus wiring or source bus wiring occurring during the manufacturing process or malfunction of the TFT at the stage when the TFT or the like is formed, an active matrix substrate that functions normally It has been conventionally proposed to sort out.

On the other hand, conventionally, it is known that the TFT threshold voltage changes due to static electricity generated during the rubbing treatment of the alignment film. The screen of a display device using such a TFT includes:
A striped pattern appears along the gate bus wiring and the source bus wiring, and good image display is not performed. In addition, static electricity generated by the rubbing treatment may cause dielectric breakdown at the intersection between the gate bus wiring and the source bus wiring. When such dielectric breakdown occurs, a leak current is generated between these wirings, which causes deterioration of TFT characteristics. Therefore, to prevent the generation of such static electricity,
It has been conventionally proposed to form a short ring for electrically connecting a gate bus wiring and a source bus wiring to an outer peripheral portion of a region where a TFT and a pixel electrode are formed.

(Problems to be Solved by the Invention) However, in the above-described process, TFT
In order to inspect the active matrix substrate on which is formed, since it is necessary to measure a potential difference between each part such as between a gate bus wiring and a source bus wiring, it is necessary to adopt a structure without a short ring. On the other hand, as described above, in order to prevent TFT characteristic deterioration, it is necessary to provide the short ring. As described above, the inspection of the active matrix substrate and the formation of the short ring are contradictory to each other. Thus, in the conventional active matrix type liquid crystal display device,
There is a problem that it is not possible to achieve both.

The present invention is to solve such a problem, and an object of the present invention is to disconnect and short-circuit a scanning line and a signal line.
It is another object of the present invention to provide a method of manufacturing an active matrix liquid crystal display device that can detect a malfunction of a switching element and can also prevent an adverse effect due to static electricity generated by a rubbing process.

(Means for Solving the Problems) In a method for manufacturing an active matrix liquid crystal display device according to the present invention, a scanning line and a signal line crossing each other, and the scanning line and the signal line are surrounded by an insulating substrate. Forming a switching element and a picture element electrode in a region; inspecting disconnection and short-circuit of the scanning line and the signal line, and characteristics of the switching element; and forming a metal film on the entire surface of the insulating substrate And forming a short ring that electrically connects the scanning line and the signal line in the outer peripheral portion of the region where the switching element and the pixel electrode are formed by patterning the metal film. Forming a light shield covering the switching element, and forming a black matrix covering the scanning line, the signal line, and a peripheral portion of the picture element electrode; Rubbing treatment by forming an alignment film on the surface,
Thereby, the above object is achieved.

(Operation) In the method of manufacturing an active matrix liquid crystal display device according to the present invention, when the switching element, the picture element electrode, and the like are formed on the insulating substrate, disconnection and short circuit of each wiring formed on the substrate, and An inspection of the switching element characteristics is performed. After this inspection is completed, a short ring is formed to electrically connect the scanning line and the signal line.
Next, an alignment film is formed, and a rubbing process is performed on the alignment film. At this time, even if static electricity is generated by the rubbing treatment, the scanning lines and the signal lines are electrically connected, so that the scanning lines, the signal lines, and the switching elements are not adversely affected.

In the method of manufacturing an active matrix liquid crystal display device according to the present invention, the short ring is formed simultaneously with the light shield covering the switching element and the black matrix covering the scanning line, the signal line, and the periphery of the pixel electrode. Thereby, a short ring can be formed without increasing the number of steps.

(Example) An example of the present invention will be described below. FIG. 1 schematically shows an active matrix substrate manufactured by one embodiment of a method for manufacturing an active matrix liquid crystal display device of the present invention. FIG. 2 shows a partially enlarged view of the substrate of FIG. FIG. 3 is a sectional view showing the vicinity of the TFT 20 shown in FIG. The method of manufacturing the active matrix liquid crystal display device according to the present embodiment includes a method of forming a gate bus line 12, a source bus line 13,
TFT 20 (second area)
And a step of forming the picture element electrode 9. The gate wiring 12 functions as a scanning line, and the source bus wiring 13 functions as a signal line. Further, the TFT 20 functions as a switching element.

The TFT 20 is manufactured by a known manufacturing method. As shown in FIG. 3, a base coat insulating film 2 was formed on an insulating substrate 1 made of glass or the like, and a gate bus wiring 12 and a gate electrode 3 branched therefrom were formed on the base coat insulating film 2. A gate insulating film 4 made of SiN _x , SiO _x, or the like was formed on a portion of the substrate 1 excluding the peripheral portion so as to cover the gate bus wiring 12 and the gate electrode 3. An a-Si semiconductor film 5 is formed on the gate insulating film 4 at a position corresponding to the position above the gate electrode 3.
Are formed (FIG. 3). On one end of the a-Si semiconductor film 5, a source electrode 7 is formed via a phosphorus-doped a-Si film 6, and on the other end of the a-Si semiconductor film 5, phosphorus-doped a-Si A drain electrode 8 is formed via the film 6. The pixel electrode 9 is formed on the gate insulating film 4.
Is formed, and the end of the drain electrode 8 is connected to the pixel electrode 9.

The source bus wiring 13 includes a source electrode 7 and a drain electrode 8
Is formed simultaneously with the formation of At the intersection of the gate bus line 12 and the source bus line 13, a rectangular insulating film 21 is interposed as shown in FIG. The insulating film 21 is made of an a-Si film, and is provided to prevent a short circuit between the gate bus wiring 12 and the source bus wiring 13. Also, insulating film
21 is formed simultaneously with the formation of the a-Si semiconductor film 5 of the TFT 20.

At the stage when the TFT 20 and the pixel electrode 9 were formed on the active matrix substrate as described above, the disconnection and short-circuit of the gate bus wiring 12 and the source bus wiring 13 and the characteristics of the TFT 20 were inspected. By this inspection, only the normally functioning active matrix substrate is selected. Inspection of the disconnection and short-circuit of the bus wiring, and the characteristics of the TFT are performed by bringing a prober needle into contact with the gate electrode 3, the source electrode 7, the drain electrode 8 and the pixel electrode 9, respectively. Each signal was input and the output signal at the drain electrode 8 was confirmed by a three-terminal method.

After this inspection, a passivation film is formed on the entire surface of the substrate 1.
Formed 10. This passivation film 10 is made of SiN _x , Si
Consist O _X, etc., in the periphery of the substrate 1, it is removed by photolithography and etching.

Next, on the passivation film 10, Al, Ta, Cr, Ti,
A metal film such as Ni was formed. By patterning the metal film, a short ring 14 (FIG. 1) for electrically connecting the gate bus line 12 and the source bus line 13 is formed around the outer periphery of the region where the TFT 20 and the pixel electrode 9 are formed. Formed. At this time, the light shield 15 (FIGS. 2 and 3) covering the TFT 20, the gate bus wiring 12 and the source bus wiring 13
Black matrix 16 covering the peripheral portion of the pixel electrode 9
(FIG. 2) were formed simultaneously. These short rings
14, the light shield 15, and the black matrix 16 can be formed by a single photo process of the metal film.

The short ring 14 is formed in a frame shape around the substrate 1 and is electrically connected to the gate bus wiring 12 and the source bus wiring 13 to keep the wirings 12 and 13 at the same potential.

The light shield 15 prevents irradiation light from entering the TFT 20 from the direction indicated by the arrow A in FIG. This light shield 1
5, the operating characteristics of the TFT 20 are stabilized as follows. TF
T20 gate voltage V _G - 4 showing the characteristics of drain current I _d
In the figure, a characteristic curve a represents TF in a dark state where no light is irradiated.
This is a T characteristic, and a characteristic curve b shows a TFT characteristic obtained by irradiating irradiation light with the light shield 15 provided. As shown in FIG. 4, the characteristic curve b is almost the same as the characteristic curve a in the dark state even when the light irradiation is performed, and it is understood that the TFT characteristic is stable.

The black matrix 16 blocks light that passes through portions where the gate bus lines 12 and the source bus lines 13 which do not contribute to display are formed. Black matrix 16
Are superimposed on the peripheral portion of the pixel electrode 9 to prevent light from leaking from the peripheral portion of the pixel electrode 9. The black matrix 16 that performs such a function improves the contrast.

Next, a rubbing treatment was performed after a polymer resin such as polyimide was applied to the entire surface of the substrate 1 and baked. During this rubbing process, static electricity is most likely to be generated in each manufacturing process of the liquid crystal display device, and the static electricity may cause problems such as insulation failure and TFT operation failure. However, as shown in FIG. When the ring 14 is formed, the gate bus line 12 and the source berth line 13 are electrically connected by the short ring 14, so that the insulation failure between the gate bus line 12 and the source bus line 13 is poor. And
It is possible to reliably prevent the occurrence of an operation failure or the like of the TFT 20. The short ring 14 is removed by etching or the like after the rubbing process.

On the other hand, the rubbing process is also performed on the opposite substrate to be bonded to the substrate 1 after the polyimide is applied and baked in the same manner. Then, the two substrates on which the rubbing process has been completed are bonded together, and liquid crystal is sealed between the two substrates to complete the liquid crystal display device.

As described above, in one embodiment of the manufacturing method of the present embodiment, when the TFT 20 and the pixel electrode 9 are formed on the glass substrate 1, disconnection and short-circuit of the gate bus line 12 and the source bus line 13 and the TFT After performing a characteristic inspection and selecting a normally functioning active matrix substrate, since the short ring 14 is formed, the inspection can be performed.
In addition, the short ring 14 can be formed.
Further, in this embodiment, since the short ring 14 can be formed simultaneously with the light shield 15 and the black matrix 16, it is not necessary to particularly provide a step for forming the short ring 14.

Note that the present invention is not limited to the case where the a-Si semiconductor film is used as in the above-described embodiment, but is applicable to the case where a p-Si semiconductor film is used.

(Effects of the Invention) In the method for manufacturing an active matrix liquid crystal display device according to the present invention, when the switching element and the picture element electrode are formed on the insulating substrate, disconnection and short circuit of the scanning line and the signal line, and the switching element Inspection of the malfunction of the above and after selecting only the active matrix substrate that functions normally, the short ring connecting the scanning line and the signal line is formed, so that the above inspection and the formation of the short ring are compatible. Can be done. Therefore, according to the method of manufacturing an active matrix liquid crystal display device of the present invention,
An active matrix liquid crystal display device can be obtained with a high production yield.

[Brief description of the drawings]

FIG. 1 is a plan view schematically showing an active matrix substrate manufactured by one embodiment of the method for manufacturing an active matrix liquid crystal display device of the present invention, FIG. 2 is a partially enlarged view of the substrate of FIG. FIG. 4 is a cross-sectional view showing the vicinity of the TFT 20 shown in FIG. 2, and FIG.
FIG. 6 is a diagram illustrating a state where a relationship between drain currents changes. 1 ... glass substrate, 3 ... gate electrode, 5 ... a-Si semiconductor film, 7 ... source electrode, 8 ... drain electrode, 9 ...
... picture element electrode, 12 ... gate bus wiring, 13 ... source bus wiring, 14 ... short ring, 15 ... light shield, 16 ...
... black matrix, 20 ... TFT, 21 ... insulating film.

Claims (1)

(57) [Claims] A step of forming a scanning element and a picture element electrode in a region surrounded by the scanning line and the signal line intersecting with each other on the insulating substrate, and the scanning line; Inspecting the disconnection and short-circuit of the signal line and the characteristics of the switching element; forming a metal film on the entire surface of the insulating substrate; patterning the metal film to form the switching element and A short ring that electrically connects the scanning line and the signal line is formed in an outer peripheral portion of the region where the pixel electrode is formed, a light shield that covers the switching element, and the scanning line and the signal Forming a black matrix covering a line and a peripheral portion of the picture element electrode; and forming an alignment film on the entire surface of the insulating substrate and performing a rubbing process. Method of manufacturing a Rikusu liquid crystal display device.