JP4252126B2 - Manufacturing method of liquid crystal display device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a liquid crystal display device in which a termination wiring is formed in order to prevent damage due to static electricity during manufacture, and in particular, a method for manufacturing a liquid crystal display device suitable for manufacturing a liquid crystal display device having a built-in drive circuit. About.
[0002]
[Prior art]
The active matrix liquid crystal display device prevents crosstalk by providing each pixel with a switch that shuts off a signal when it is not selected, and is superior to a simple matrix liquid crystal display device. Display characteristics are shown. In particular, a liquid crystal display device using a TFT (Thin Film Transistor) as a switch has a high TFT drive capability, and thus exhibits excellent display characteristics comparable to a CRT (Cathode-Ray Tube).
[0003]
In general, a liquid crystal display device has a structure in which liquid crystal is sealed between two transparent substrates. Of the two opposing surfaces (opposing surfaces) of the transparent substrate, a counter electrode, a color filter, an alignment film, and the like are formed on one surface side, and a TFT, a pixel electrode, and an alignment surface on the other surface side. A film or the like is formed. Furthermore, a polarizing plate is attached to the surface opposite to the facing surface of each transparent substrate. These two polarizing plates are, for example, arranged so that the polarizing axes of the polarizing plates are orthogonal to each other, and according to this, a mode that transmits light when no electric field is applied and shields light when an electric field is applied, That is, the normally white mode is set. On the other hand, when the polarization axes of the two polarizing plates are parallel, the normally black mode is set. Hereinafter, the transparent substrate on which the TFT and the pixel electrode are formed is referred to as a TFT substrate, and the transparent substrate on which the counter electrode is formed is referred to as a counter substrate.
[0004]
In recent years, TFTs using thin film polysilicon formed by a low temperature process have been developed and used in liquid crystal display devices. In the case of forming a TFT by a low temperature process, there is an advantage that an inexpensive glass substrate can be used as the transparent substrate. In addition, since the polysilicon TFT has a high driving capability and can be miniaturized as compared with the amorphous silicon TFT, there is an advantage that the aperture ratio is improved and a bright image can be obtained. Furthermore, since the driving speed is low in the case of amorphous silicon TFT, it was necessary to prepare a driving IC separately and connect it to the liquid crystal display device. However, since the driving speed of polysilicon TFT is high, a driving (driver) circuit is required. It can be formed on a glass substrate. As a result, the number of input terminals of the liquid crystal display device can be reduced to about 40, and the product cost can be reduced.
[0005]
FIG. 9 is an enlarged plan view showing a part of a TFT substrate of a liquid crystal display device being manufactured by a conventional method, and FIG. 10 is a schematic diagram showing the entire TFT substrate of the liquid crystal display device. A manufacturing method of the liquid crystal display device will be described with reference to these drawings.
First, a polysilicon film 52a is formed on the glass substrate 50, and a gate insulating film (not shown) is formed thereon. Thereafter, a plurality of gate bus lines 55 passing over the polysilicon film 52a are formed. Then, impurities are introduced into the polysilicon film 52a to form a source / drain. The source / drain and the gate bus line 55 constitute a TFT 70.
[0006]
Next, after forming an interlayer insulating film (not shown) on the glass substrate 50, the data bus line 57 is formed so as to intersect the gate bus line 55 at a right angle. The data bus line 57 is electrically connected to the drain of the TFT 70 through a contact hole 53a formed in the interlayer insulating film.
Then, after forming an interlayer insulating film (not shown) on the entire surface of the substrate, a pixel electrode 59 made of ITO (indium tin oxide) is formed on the interlayer insulating film. The pixel electrode 59 is electrically connected to the source of the TFT 70 through a contact hole 53b provided in the interlayer insulating film. As shown in FIG. 9, the TFT 70 and the pixel electrode 59 are formed for each rectangular region defined by the gate bus line 55 and the data bus line 57. One rectangular area is one pixel, and a display area 63 shown in FIG. 10 is an area in which these pixels are gathered.
[0007]
In order to prevent damage due to static electricity generated in various parts of the manufacturing process of the liquid crystal display device, one end side of each gate bus line 55 and each data bus line 57 is extended to the outside of the display area 63, and a termination wiring (GND line). The gate bus lines 55 and the data bus lines 57 are connected at the same potential. On the other end side of the gate bus line 55 and the data bus line 57, a gate driver circuit 61 and a data driver circuit 62 are formed by TFTs formed simultaneously with the TFTs 70 in the display region 63. The gate driver circuit 61 and the data driver circuit 62 are connected to an input terminal 71 for connection to an external circuit via a flexible cable. In this case, the input terminal 71 is also connected to the termination wiring 55a in order to avoid damage to the driver circuits 61 and 62 due to generation of static electricity in the manufacturing process. In this way, the TFT substrate is manufactured. In FIG. 10, G _{1 to} G _N and D _{1 to} D _N indicate gate bus lines and data bus lines extending outward from the display area 63.
[0008]
On the other hand, a counter substrate in which a counter electrode and a color filter are formed on a glass substrate is prepared. Then, as shown in FIG. 11, the surface of the TFT substrate 81 where the bus lines 55 (57) and the TFT 70 are formed and the surface of the counter substrate 82 where the counter electrode (ITO film) 82a is formed are opposed to each other. The liquid crystal 83 is filled between them and sealed with a sealant 84.
[0009]
Thereafter, the TFT substrate 81 and the counter substrate 82 are cut at a portion inside the termination wirings 55a and 57a to have a predetermined size. Thereby, a liquid crystal display device is completed.
[0010]
[Problems to be solved by the invention]
However, in the above-described conventional method for manufacturing a liquid crystal display device, the input terminal 21, the gate bus lines 55, and the data bus lines 57 are connected to each other via the termination wirings 55a and 55b. (Substrate inspection) cannot be performed.
[0011]
Usually, the bus lines 55 and 57 are formed of a metal thin film such as aluminum. However, in the polysilicon TFT liquid crystal display device, the film thickness of the thin film wiring (bus line) is generally larger than that of the amorphous silicon TFT. When the substrate is cut, the gate bus line 55 and the data bus line 57 tend to peel off. For this reason, when the glass substrate is cut, a part of the metal thin film is peeled off and comes into contact with the counter electrode (ITO film) 82a of the counter substrate 82 as shown in FIG.
[0012]
In order to avoid such a problem, it may be considered that the counter electrode (ITO film) 82a outside the sealant 84 is deleted. However, in this case, an ITO film patterning step is required, resulting in an increase in manufacturing cost. Moreover, as shown in FIG. 13, the piece 85 of the wiring peeled off from the glass substrate may short-circuit between adjacent bus lines 55 (57). Further, the gate bus line 55 and the data bus line 57 made of a metal thin film may corrode from the cut surface, and the corrosion may progress toward the inside.
[0013]
It is also conceivable to form an ITO film on the scribe line and connect the bus line and the termination wiring via the ITO film. In this case, since the formation of the ITO film is the final process, I cannot take measures.
The present invention is capable of preventing damage due to static electricity generated during manufacturing, performing inspection before cutting the termination wiring, and avoiding malfunction caused by peeling of the wiring at the time of cutting. It is an object to provide a method for manufacturing a display device.
[0014]
[Means for Solving the Problems]
The problem described above is that a plurality of signal electrodes and scanning electrodes passing through the display area of the transparent substrate are formed to define pixels, a polysilicon thin film transistor and a pixel electrode are formed for each pixel, and the outside of the display area A plurality of first impurity resistors made of impurity-introduced polysilicon connected to the signal electrode and the scan electrode, an inspection circuit connected to the plurality of impurity resistors, a termination wiring, the inspection circuit, and the termination wiring; A step of forming a second impurity resistor made of impurity-introduced polysilicon for connecting between them, a step of performing an inspection by driving the inspection circuit, and cutting the transparent substrate at a portion of the first impurity resistor And solving the problem by a method for manufacturing a liquid crystal display device.
[0017]
The operation will be described below.
In the present invention, a plurality of impurity resistors made of impurity-doped polysilicon are formed outside the display region, and signal electrodes (data bus lines), scanning electrodes (gate bus lines), and termination wirings are connected via the impurity resistors. Connecting. As a result, even when a voltage is applied to the signal electrode and the scan electrode, an impurity resistance is interposed between the signal electrode and the scan electrode, so that a short circuit is not caused, and the termination wiring remains connected. Inspection can be performed.
[0018]
In this case, the resistance value of the impurity resistance is preferably 50 kΩ to 1 MΩ. If the resistance value of the impurity resistor is too small, the inspection cannot be performed with the termination wiring connected. On the other hand, when the resistance value of the impurity resistance is too large, the effect of preventing damage due to static electricity during the production is reduced.
Although the resistance value of the impurity resistance can be adjusted by the amount of impurities introduced into the polysilicon, it is easy to obtain a resistance value of 50 kΩ to 1 MΩ with a length of several mm. Further, since the polysilicon film serving as the impurity resistance can be formed simultaneously with the polysilicon film serving as the active region of the polysilicon thin film transistor in the display region, an increase in the number of manufacturing steps can be suppressed.
[0019]
In the case of a liquid crystal display device using a polysilicon thin film transistor, since a polysilicon film is formed at an early stage of the manufacturing process, the impurity resistance is also formed at a relatively fast stage. Therefore, simultaneously with the formation of the signal electrode and the scan electrode, the signal electrode and the scan electrode can be connected to the termination wiring through the impurity resistance. Thereby, the effect which prevents the damage by static electricity can be acquired from the comparatively early stage of manufacture.
[0020]
Furthermore, in the present invention, since the transparent substrate is cut at the impurity resistance portion made of polysilicon, a short circuit due to peeling of the metal thin film is avoided unlike the case of the metal thin film.
In the case of an active matrix liquid crystal display device, a polysilicon thin film transistor can be formed outside the display region, and a driving circuit can be formed using these thin film transistors. Furthermore, by forming an inspection circuit on the glass substrate, a special inspection device is not necessary. Therefore, when a polysilicon thin film transistor is formed in a display area on a transparent substrate, a polysilicon thin film transistor is also formed outside the display area, and a drive circuit or an inspection circuit is formed by the polysilicon thin film transistor outside the display area. It is preferable to do.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
(First embodiment)
1 to 4 are sectional views showing a manufacturing method of the liquid crystal display device according to the first embodiment of the present invention, FIG. 5 is an enlarged plan view showing a part of a TFT substrate being manufactured, and FIG. It is a schematic diagram which shows the whole TFT substrate. 1 and 2 are cross-sectional views taken along line AA in FIG. 5, and FIGS. 3 and 4 are cross-sectional views taken along line BB in FIG. In the following description, the manufacture of the TFT in the display area 24 is described. However, the TFTs in the gate driver circuit 22 and the data driver circuit 23 are formed at the same time as the TFT 20 in the display area 24, and the driver circuits 22, 23 are formed. The internal wiring can be formed simultaneously with the gate bus line 15 and the data bus line 17.
[0022]
First, as shown in FIGS. 1A and 3A, a base protective film 11 made of SiO ₂ is formed on a glass substrate 10 to a thickness of about 200 nm, and then the base protective film 11 is formed by CVD. Then, an amorphous silicon film 12 is formed to a thickness of about 50 nm. At this time, for example, monosilane and hydrogen gas are used to form the amorphous silicon film 12.
[0023]
Next, the amorphous silicon film 12 is irradiated with an excimer laser to change the amorphous silicon into polysilicon. Thereafter, the polysilicon film is selectively etched by dry etching using chlorine gas, and as shown in FIGS. 1B, 3B, 5 and 6, the TFT 20 and the impurity resistances R ₁ to R ₁ . R _N, GR ₁ ~GR _N, only the region for forming the DR ₁ ~DR _N polysilicon film 12a, 12b, leaving the 12c.
[0024]
Thereafter, an insulating film 14 is formed on the entire upper surface of the substrate 10 by plasma CVD, and the polysilicon films 12a, 12b, and 12c are covered with the insulating film 14. This insulating film 14 is formed, for example, by depositing SiO ₂ to a thickness of 150 nm.
Next, as shown in FIGS. 1C and 3C, an aluminum film is formed on the entire upper surface of the substrate 10 to a thickness of about 300 nm, and the aluminum film is patterned to form a plurality of parallel films. Two gate bus lines (scanning electrodes) 15 and a termination wiring 15a are formed simultaneously. Of the gate bus line 15, the portion located above the polysilicon film 12 a becomes the gate of the TFT 20. Incidentally, in FIG. 6, G ₁ ~G _N denotes a gate bus line 15 which extends out to the outside from the display area 24.
[0025]
Thereafter, the portion of the insulating film 14 not covered with the gate bus line 15 and the termination wiring 15a is removed by etching with CHF ₃ gas. Then, for example, boron (B) is ion-implanted into the polysilicon film 12 a exposed on both sides of the gate bus line 15 to form the source / drain of the TFT 20. At the same time, impurities are ion-implanted into the polysilicon films 12b and 12c at a concentration of 5 × 10 ¹⁴ / cm ² , for example, so that the resistance values of the polysilicon films 12b and 12c are about 50 kΩ to 1 MΩ. Thus, impurities resistance R ₁ to R _N shown in FIG. _{6, GR 1 ~GR N, DR} 1 ~DR N is formed. As conditions for ion implantation, for example, when boron (B) is used as an impurity, the acceleration voltage is 30 kV, and when phosphorus (P) is used as an impurity, the acceleration voltage is 10 kV.
[0026]
Next, as shown in FIGS. 2A and 4A, an interlayer insulating film 16 is formed on the entire surface of the substrate 10 by, eg, plasma CVD, and the gate bus line 15, The end point wiring 15a and the polysilicon films 12a, 12b, and 12c are covered.
Next, as shown in FIGS. 2B and 4B, the interlayer insulating film 16 is selectively etched, and contact holes 16a reaching the source / drain (polysilicon film 12a) of the TFT 20; Contact holes 16b exposing both ends of the polysilicon films 12b and 12c, contact holes 16c exposing portions of the gate bus line 15 and termination wiring 15a on the polysilicon film 12b side, and contact holes exposing both ends of the termination wiring 15a. (Not shown) is opened. Thereafter, an aluminum film is formed on the entire upper surface of the substrate 10 by sputtering, for example, to cover the interlayer insulating film 16, and the aluminum film is etched to form a data bus line (signal electrode) 17, a termination wiring 17a, an intermediate electrode 17c, Connection wirings 17d and 17e are formed. In this case, the data bus line 17 is connected to the drain of the TFT 20 through the contact hole 16a, and the intermediate electrode 17c is connected to the source of the TFT 20 through another contact hole 16a. The gate bus line 15 is electrically connected to the polysilicon film 12b through contact holes 16b and 16c and connection wirings 17d and 17e. The data bus line 17 is connected to the polysilicon film 12c (impurity resistances DR _{1 to} DR _N ) through a contact hole (not shown), and is further electrically connected to the termination wiring 17a through the polysilicon film 12c. Furthermore, the termination wiring 15a and the termination wiring 17a are connected through a contact hole (not shown). In FIG. 6, D _{1 to DN} indicate the data bus lines 17 extending outward from the display area 24.
[0027]
Next, as shown in FIGS. 2C and 4C, an interlayer insulating film 18 is formed on the entire surface of the substrate 10 to a thickness of about 300 nm, and the data bus lines 17, The termination wiring 17a, the intermediate electrode 17c, and the connection wirings 17d and 17e are covered. Then, the interlayer insulating film 18 is selectively etched to form a contact hole reaching the intermediate electrode 17c. At the same time, in the region where the input terminal 21 (see FIG. 6) is formed, an opening is formed so that the wiring is exposed.
[0028]
Next, an ITO film is formed on the entire surface of the substrate 10 by sputtering, and the ITO film is selectively etched to form the pixel electrode 19. Further, in the formation region of the input terminal 21 (see FIG. 6), the exposed wiring is covered with an ITO film, and these ITO films are used as the input terminal 21. Thereafter, an alignment film (not shown) is formed on the display region 24 of the substrate 10. In this way, the TFT substrate is completed.
[0029]
On the other hand, a counter substrate in which a counter electrode, a color filter, an alignment film, and the like are formed on a glass substrate is prepared. Then, as shown in FIG. 7, the surface of the TFT substrate 31 on which the TFT 20 and the like are formed and the surface of the counter substrate 32 on which the counter electrode 32a and the like are formed face each other, and the liquid crystal 33 is filled therebetween. Then, the sealing agent 34 is used for sealing.
Next, an inspection apparatus (not shown) is connected to the input terminal 21 shown in FIG. At this time, impurity resistances R _{1 to} R _N , GR _{1 to} GR _N , DR ₁ having resistance values of 50 kΩ to ₁ MΩ between the termination wirings 15 a and 17 a and the input terminal 21, the gate bus line 15 and the data bus line 17. since ～DR _N is connected, it is left end wires 15a, 17a are connected, it is possible to perform without hindrance test.
[0030]
After that, when it is determined that there is no abnormality in the inspection, the portions indicated by broken lines in FIGS. 6 and 7, that is, along the cutting lines passing through the impurity resistances R _{1 to} R _N , GR _{1 to} GR _N , DR _{1 to} DR _N Then, the TFT substrate 31 and the counter substrate 32 are cut. Thereafter, polarizing plates are arranged on the outer surfaces of the TFT substrate 31 and the counter substrate 32 to complete the liquid crystal display device.
In the present embodiment, impurity resistances R _{1 to} R _N , GR _{1 to} GR _N , 50 kΩ to ₁ MΩ are all provided between the termination wirings 15 a and 17 a and the gate bus line 15, the data bus line 17, and the input terminal 21. Since DR _{1 to} DR _N are provided, the termination wirings 15a. Substrate inspection can be performed while 17a remains connected. As a result, the defective substrate does not have to be made into a panel, and the manufacturing cost can be reduced. In addition, since each gate bus line 15 and each data bus line 17 are electrically connected to each other via termination wirings 15a and 17a, damage due to static electricity generated in various parts of the manufacturing process can be avoided. Moreover, in the present embodiment, the impurity resistances R _{1 to} R _N , GR _{1 to} GR _N , and DR _{1 to} DR _N are formed at a relatively early stage, and the gate bus line 15 and the data bus line 17 are formed. At the same time, since it is connected to the termination wirings 15a and 17a, an effect of preventing damage due to static electricity from the initial stage of the manufacturing process can be obtained.
[0031]
Furthermore, in the present embodiment, when the substrate is cut, it is cut at the portion of the impurity resistances R _{1 to} R _N , GR _{1 to} GR _N , DR _{1 to} DR _N , that is, the portion of the polysilicon film. Unlike metal wiring such as the above, short circuit due to peeling of the wiring is prevented. As a result, the manufacturing yield is improved, and the product cost can be reduced. Moreover, corrosion of the metal from the cut surface is avoided.
[0032]
(Second Embodiment)
FIG. 8 is a schematic view showing a manufacturing method of the liquid crystal display device according to the second embodiment of the present invention. 8, the same components as those in FIG. 6 are denoted by the same reference numerals, and detailed description thereof is omitted.
In the present embodiment, as shown in FIG. 8, driver circuits 22 and 23 are formed on one end side of the gate bus line and the data bus line, and inspection circuits 25 and 26 are formed on the other end side. Then, first impurity resistors GR _{1 to} GR _N and DR _{1 to} DR _N are formed between the gate bus line and the data bus line and the inspection circuits 25 and 26, and the inspection circuits 25 and 26 and the termination wiring 15a, Second impurity resistances Gr _{1 to} Gr _N and Dr _{1 to} Dr _N are formed between the _first impurity resistances 17a and 17a. These impurity resistances Gr _{1 to} Gr _N and Dr _{1 to} Dr _N are formed simultaneously with the polysilicon film that becomes the source / drain of the polysilicon TFT, as in the first embodiment.
[0033]
At the time of substrate inspection, a power supply voltage and a signal are supplied to the inspection circuits 25 and 26 to perform a predetermined inspection. Thereafter, the substrate is cut along a portion indicated by a broken line in the drawing, that is, along a straight line passing through the impurity resistances GR _{1 to} GR _N and DR _{1 to} DR _N.
Also in this embodiment, in addition to obtaining the same effect as in the first embodiment, the dedicated inspection circuits 25 and 26 are provided, so that it is not necessary to connect to an external inspection circuit, and the inspection process is simplified. There is an effect that can be made.
[0034]
【The invention's effect】
As described above, according to the present invention, since the impurity resistance made of impurity-doped polysilicon is formed between the signal electrode and the scanning electrode and the termination wiring, even if a voltage is applied to the signal electrode and the scanning electrode. Since the impurity resistance is interposed between the signal electrode and the scan electrode, the short-circuit state is not caused, and the inspection can be performed with the termination wiring being connected. Thereby, the reliability of the liquid crystal display device is improved.
[0035]
Further, in the present invention, since the substrate is cut at the impurity resistance portion made of polysilicon, a short circuit due to peeling of the metal thin film is avoided and corrosion from the cut surface can be avoided, thereby improving the manufacturing yield.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view (part 1) illustrating a method for manufacturing a liquid crystal display device according to a first embodiment of the present invention, and is a cross-sectional view in a TFT formation region;
FIG. 2 is a cross-sectional view (No. 2) illustrating the method for manufacturing the liquid crystal display device according to the first embodiment of the present invention, and is a cross-sectional view in a TFT formation region;
FIG. 3 is a cross-sectional view (part 3) illustrating the method for manufacturing the liquid crystal display device according to the first embodiment of the present invention, and is a cross-sectional view in the impurity resistance forming region;
FIG. 4 is a cross-sectional view (part 4) illustrating the method for manufacturing the liquid crystal display device according to the first embodiment of the present invention, and is a cross-sectional view in the impurity resistance forming region;
FIG. 5 is an enlarged plan view showing a part of the TFT substrate in the middle of manufacture according to the first embodiment of the present invention.
FIG. 6 is a schematic view showing the entire TFT substrate in the process of manufacturing according to the first embodiment of the present invention.
FIG. 7 is a cross-sectional view showing a joint portion between a TFT substrate and a counter substrate in the method for manufacturing a liquid crystal display device according to the first embodiment of the present invention.
FIG. 8 is a schematic view showing a method for manufacturing the liquid crystal display device of the second embodiment of the present invention.
FIG. 9 is an enlarged plan view showing a part of a TFT substrate of a liquid crystal display device being manufactured by a conventional method.
FIG. 10 is a schematic view showing the entire TFT substrate of the liquid crystal display device.
FIG. 11 is a cross-sectional view showing a bonding portion between a TFT substrate and a counter substrate in a method for manufacturing a liquid crystal display device according to a conventional method.
FIG. 12 is a cross-sectional view showing a conventional problem (No. 1).
FIG. 13 is a cross-sectional view showing a conventional problem (No. 2).
[Explanation of symbols]
10,50 glass substrate,
12 Amorphous silicon film,
12a to 12c, 52a polysilicon film,
15, 55 gate bus line (scanning electrode),
15a, 17a, 55a, 57a Termination wiring,
17, 57 Data bus line (signal electrode),
19 pixel electrodes,
20 TFT,
22 Gate driver circuit,
23 Data driver circuit,
25, 26 Inspection circuit,
31, 81 TFT substrate,
32, 82 counter substrate,
34,84 sealant,
_{R 1 ~R N, GR 1 ~GR} N, DR 1 ~DR N impurity resistance.

Claims (2)

A plurality of signal electrodes and scanning electrodes that pass through the display area of the transparent substrate are formed to define pixels, a polysilicon thin film transistor and a pixel electrode are formed for each pixel, and the signal electrodes and the scanning are formed outside the display area. A plurality of first impurity resistors made of impurity-introduced polysilicon connected to the respective electrodes, an inspection circuit connected to the plurality of impurity resistors, a termination wiring, and an impurity connecting between the inspection circuit and the termination wiring Forming a second impurity resistor made of introduced polysilicon;
A step of performing inspection by driving the inspection circuit;
And a step of cutting the transparent substrate at the portion of the first impurity resistance. A polysilicon thin film transistor is formed outside the display region simultaneously with the formation of the polysilicon thin film transistor in the display region, and a drive circuit for driving the thin film transistor in the display region is formed by the polysilicon thin film transistor. The manufacturing method of the liquid crystal display device of Claim 1 .

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