JP3416718B2 - Manufacturing method of liquid crystal display device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a liquid crystal display device, and more particularly, to a technique for forming a conductive film pattern to be formed outside an effective area on a substrate, and more specifically to a conductive film pattern. Related to technology for preventing static electricity defects.

[0002]

2. Description of the Related Art In recent years, liquid crystal display devices have been used as
It is expected to be used not only for notebook personal computers, car navigation devices, various types of portable terminals such as electronic notebooks and PHSs, but also for television displays and display monitors that replace CRTs. However, when replacing the CRT, the price of the current liquid crystal display device is considerably high, and therefore measures for cost reduction are desired, and improvement of the manufacturing yield (the number of non-defective products / the number of input) is an issue. Has become.

In particular, the size of the glass substrate used for manufacturing an active matrix type liquid crystal display device is increasing, and a decrease in yield due to electrostatic breakdown is an important issue.

As a conventional technique, a method for manufacturing an active matrix type liquid crystal display device using anodic oxidation will be described below as an example. FIG. 6 is a plan view showing the outline of an active matrix substrate which is being manufactured. An image display unit 12 in which TFTs (thin film transistors; not shown) as switching elements for liquid crystals are arranged in a matrix is formed on a glass substrate 11, and a gate for inputting a drive signal from the outside is formed. A signal input terminal 13 and a source signal input terminal 14 for inputting a data signal are formed. VGA (Video Graphics Arra
In the case of y), the number of gate signal input terminals 13 is 480.
The number of source signal input terminals 14 is 640, and the number of TFTs is 480 × 640.
ics Array), the number of gate signal input terminals 13 is 768, the number of source signal input terminals 14 is 1024,
The number of TFTs and picture elements is 768 × 1024.

After assembling the liquid crystal display cell, the glass substrate 11 is cut at the separation boundary line 15 shown by the chain double-dashed line before the liquid crystal is filled. The area inside the separation boundary line 15 is the effective area 1 as an active matrix substrate.
It is 6. A pair of L's for anodizing TFTs on the glass substrate 11 mainly in the region outside the separation boundary line 15.
A V-shaped conductive film pattern 17 is formed. One end of the conductive film pattern 17 is electrically connected to the gate signal input terminal 13. FIG. 7 shows a state in which an interlayer insulating film 18 is formed on the conductive film pattern 17, but this interlayer insulating film 18 covers the entire surface of the glass substrate 11 except the gate signal input terminal 13 and the source signal input terminal 14. Is formed in. The interlayer insulating film 18 is not shown in FIG.

At the time of anodic oxidation of the TFT portion, the two conductive film patterns 17 are immersed in an electrolytic solution with an electrode clip sandwiched between the portions near the edges of the glass substrate 11,
One conductive film pattern 17 to the other conductive film pattern 1
By passing a current through 7, a current is passed through the gate signal line and a part of the surface of the gate of each TFT section is oxidized to form an insulating film. As a result, insulation is provided between the gate and the source / drain in the TFT section. Anodizing has the advantage that a uniform insulating film can be formed relatively easily on a large number of TFT parts.

[0007]

In the case of the above-mentioned conventional structure, no countermeasure against static electricity is taken, and static electricity enters the image display portion 12 from the end portion of the glass substrate 11 through the conductive film pattern 17. Alternatively, a phenomenon may occur in which a charged glass substrate is discharged through the conductive film pattern 17 at the edge of the substrate. In the manufacturing process of the TFT part, due to the nature of the manufacturing line, there are parts where the glass substrate is adsorbed and parts where the robot hand passes near the glass substrate, so it is impossible to completely suppress the charging of the substrate. Therefore, the image display portion 12 is formed from the end portion of the substrate through the conductive film pattern 17.
When static electricity enters the device or discharges from the charged edge of the substrate, it causes defects such as destruction of the interlayer insulating film between the gate and source of the TFT part, which is a factor that reduces the yield. Was there.

In the above description, the case where the conductive film pattern 17 for anodic oxidation is formed in the region outside the separation boundary line 15 of the glass substrate 11 has been described as an example. The above problem occurs not only when the pattern is formed but also when an arbitrary conductive film pattern is formed outside the separation boundary line.

Japanese Unexamined Patent Publication No. 7-225393 discloses the following technique for countermeasures against static electricity. This will be described with reference to FIGS. 8 and 9. An image display unit 23 in which TFTs are arranged in a matrix is formed in the effective area 22 of the glass substrate 21, and a gate signal input terminal 24 for inputting a drive signal from the outside and a data signal are input. Source signal input terminal 25 is formed. Outside the effective area 22 on the glass substrate 21,
The short pattern 26 for preventing the dielectric breakdown of the TFT part from static electricity during the manufacturing process is formed in an L shape, and the end portions of the individual gate signal input terminals 24 and the source signal input terminals 25 are zigzag with respect to the short pattern 26. Are electrically connected via the resistance patterns 27a and 27b. By electrically keeping the gates and sources of all the TFT parts at the same electric potential through the short pattern 26, it is possible to prevent the interlayer insulating film between the gate and the source of the TFT parts from being destroyed due to static electricity. .

The glass substrate 21 is cut at the separation boundary 28 at some stage of the manufacturing process, and the effective area 22 is taken out. If the gate signal input terminal 24 and the source signal input terminal 25 are simply connected to the short pattern 26 as they are without the zigzag resistance patterns 27a and 27b, the cut surface is exposed to the substrate end surface, and the cut end surface area is reduced. Since it is relatively large, it serves as an entrance and exit for static electricity, and there is a risk of electrostatic damage after cutting. Zigzag resistance pattern 2
7a and 27b are for preventing electrostatic breakdown after this cutting. In this respect, the premises of the present invention and the technology of this publication differ from those of the present invention, which mainly aims at prevention of electrostatic breakdown before cutting. Vertical zigzag resistance pattern 27a
The width of the parallel zigzag resistance pattern 27b is sufficiently smaller than that of the gate signal input terminal 24 and the source signal input terminal 25. Even if the cutting line with respect to the glass substrate 21 is slightly deviated from the predetermined separation boundary line 28, the parallel zigzag resistance pattern 27b is one of the narrow lines 1 of the elements.
Only the book is connected to the vertical zigzag resistance pattern 27a, and the area of the cut end surface of the book is sufficiently small. This cut end surface serves as an entrance / exit for static electricity, but since the area is sufficiently small, penetration and discharge are suppressed. Effective area 22
The vertical zigzag resistance pattern 27a remaining inside has a sufficiently small cross-sectional area and is enlarged several times in length, so that the resistance value is sufficiently large (R = ρ · d /
S). Vertical zigzag resistance pattern 27a with large resistance
In (1), by delaying and blunting the steep input / output waveform of static electricity, suppressing overcurrent, and lowering the voltage, electrostatic breakdown of the TFT section in the cut glass substrate is prevented.

However, the narrow width line of one of the vertical zigzag resistance pattern 27a and the remaining parallel zigzag resistance pattern 27b is apt to be broken because the cross-sectional area is too small, leading to a reduction in yield. Although the vertical zigzag resistance pattern 27a is thin when viewed as one continuous line, the width of the range occupied by the entire pattern is the original gate signal input terminal 24.
And the width of the source signal input terminal 25 is larger than the width of the source signal input terminal 25, and the adjoining interval is reduced from W1 to W2, which may cause a short circuit at the stage of a finished product, resulting in deterioration of display quality. Further, it is unavoidable that signal delay occurs due to the large resistance value. Furthermore, a zigzag resistance pattern 2
The exposure machine for forming 7a and 27b must use a stepper, and requires repeated printing of a reduced pattern, which is inefficient.

And again, in the first place, the zigzag resistance pattern 27 in the technique of the above publication is originally.
It can be said that a and 27b are related to the prevention of electrostatic breakdown after cutting the glass substrate and are meaningless even if applied to the present invention whose main purpose is to prevent electrostatic breakdown before cutting.

The present invention was devised in view of such circumstances, and the conductive film pattern forming the main part on the substrate on the outside of the effective area serves as a static electricity passage to serve as an electrostatic discharge for the image display portion. The purpose is to prevent causing defects. In particular, in the case of an active matrix substrate, when the conductive film pattern that also serves as a path for static electricity is formed as a conductive film pattern for anodization, electrostatic breakdown of the interlayer insulating film between the gate and source / drain of the TFT The purpose is to prevent.
As a result, the manufacturing yield of particularly large-sized liquid crystal display devices is improved and the cost is reduced.

[0014]

A method of manufacturing a liquid crystal display device according to a first aspect of the present invention has the following aspects. That is, one or more image display portions are formed on a substrate such as a glass substrate. These image display portions are formed inside the effective area of the substrate that is to be the final product. In the middle of the manufacturing process, the main part of the conductive film pattern is formed on the substrate in the area outside the effective area for performing, for example, anodic oxidation and other treatments. One end of the conductive film pattern is electrically connected to the image display unit. This conductive film pattern serves as an entrance / exit for static electricity, and there is a possibility of causing static electricity failure in the image display portion. To prevent this possibility reliably, when forming this conductive film pattern outside the effective area. Then, a conductive film pattern having a sufficient resistance value to prevent static electricity failure on the image display portion through the conductive film pattern is formed. Since a conductive film pattern having a large resistance value is formed as a conductive film pattern that serves as a path for static electricity, its time constant becomes sufficiently large to delay and steeply steep input / output waveforms of static electricity, and to prevent overcurrent. By suppressing and dropping the voltage, in the stage before cutting the effective area from the substrate,
For example, the gate and source of the TFT section in the screen display section /
It is possible to surely prevent static electricity failure on the image display unit such as dielectric breakdown with the drain.

Further, in the method for manufacturing a liquid crystal display device according to the first aspect of the present invention, in addition to the above , a conductive film pattern for capacitance formation is formed facing the conductive film pattern with an interlayer insulating film interposed. Rather than simply increasing the time constant by simply using the resistance value, by providing an electrostatic capacity, the CR time constant can be made sufficiently large by the resistance value and the electrostatic capacity, and the prevention of static electricity on the image display unit is more reliable. I shall.

A method for manufacturing a liquid crystal display device according to a second aspect of the present invention is the method according to the first aspect, wherein a transparent conductive film is formed as a conductive film pattern for forming a capacitance. Since the transparent conductive film is also used to form the pixel electrodes, the conductive film pattern for anodic oxidation can be formed simultaneously with the formation of the pixel electrodes.

[0017]

[0018]

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a method for manufacturing a liquid crystal display device according to the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a plan view showing the outline of an active matrix substrate which is being manufactured. An image display unit 2 is formed on a glass substrate 1 by arranging TFTs (thin film transistors; not shown) as elements for switching liquid crystals in a matrix, and a large number for externally inputting drive signals. A gate signal input terminal 3 and a large number of source signal input terminals 4 for inputting data signals are formed. After assembling the liquid crystal display cell, the glass substrate 1 is cut at the separation boundary line 5 indicated by the chain double-dashed line before the liquid crystal is sealed. An area inside the separation boundary line 5 is an effective area 6 as an active matrix substrate. A pair of conductive film patterns 7 for anodizing TFTs is formed on the glass substrate 1 mainly in the region outside the separation boundary line 5. The conductive film pattern 7 for anodic oxidation is indicated by a terminal portion 7a for fastening an electrode clip in the vicinity of the lower side of the glass substrate 1 and a broken line extending substantially along the entire length along the vertical side of the glass substrate 1. A first long pattern portion 7b and a second length which is U-turned from the end of the first long pattern portion 7b and extends long in parallel to the first long pattern portion 7b and is also indicated by a broken line. The gate signal input terminal 3 extends in an L shape from the ends of the long pattern portion 7c and the second long pattern portion 7c.
And a connection pattern portion 7d electrically connected to. The pair of conductive film patterns 7, 7 for anodic oxidation are formed symmetrically. FIG. 2 shows a state in which the interlayer insulating film 8 is formed on the conductive film pattern 7 for anodization (the first long pattern portion 7b and the second long pattern portion 7c). The interlayer insulating film 8 is formed on the entire surface of the glass substrate 1 except for the gate signal input terminal 3 and the source signal input terminal 4, and the gate and the source /
Insulation is applied to the drain. In FIG. 1, the interlayer insulating film 8 is not shown. A conductive film pattern 9 for capacitance formation is formed on the interlayer insulating film 8 above the first long pattern portion 7b and the second long pattern portion 7c of the conductive film pattern 7 for anodic oxidation. This conductive film pattern 9 is also formed symmetrically. The material of the conductive film pattern 9 for forming the capacitance is not particularly limited as long as it is a conductive film, but since a transparent conductive film such as ITO (indium tin oxide) is used as the pixel electrode, the transparent conductive material of the same material is used. If the conductive film pattern 9 for forming a capacitance is formed of a film, it can be formed at the same time as the formation of the pixel electrode, which leads to simplification of the manufacturing process.

In the conductive film pattern 7 for anodic oxidation, the first long pattern portion 7b extends over substantially the entire length of the vertical side of the glass substrate 1, and the second long pattern portion 7c extends vertically in the glass substrate 1. Since it has a length of about 80% of the side and has the terminal portion 7a and the connection pattern portion 7d other than that,
The total length of the conductive film pattern 7 is 200 on the vertical side of the glass substrate 1.
% Or more. Further, the width of the conductive film pattern 7 is made sufficiently small within the range in which the disconnection that causes the reduction in yield does not occur. Its width is 1 to 2% of the vertical side of the glass substrate 1. As a result, the resistance value of the conductive film pattern 7 for anodic oxidation is sufficiently large (R = ρ · d / S). Since the conductive film pattern 9 for forming a capacitance is formed on the long first long pattern portion 7b and the second long pattern portion 7c with the interlayer insulating film 8 interposed therebetween, The capacitances of the conductive film patterns 7 and 9 also have sufficiently large values (C∝ε · S / d).

Since the conductive film pattern 7 for anodic oxidation, which serves as a passage for static electricity, has a large resistance value and electrostatic capacitance as described above, its CR time constant (τ = C · R) becomes sufficiently large. , The steep electrostatic input / output waveform is delayed and blunted, the overcurrent is suppressed, and the voltage is dropped, so that the gate of the TFT portion due to static electricity is generated at a stage before the glass substrate 1 is cut at the separation boundary line 5. It is possible to reliably prevent dielectric breakdown between the source and the drain. Therefore, as a result, it is possible to improve the production yield of particularly large-sized liquid crystal display devices and reduce the cost.

The distance between the first long pattern portion 7b and the second long pattern portion 7c of the conductive film pattern 7 for anodic oxidation may seem narrow in the drawing, but the gate in the case of the prior art publications. The distance is very large as compared with the distance between adjacent signal input terminals or source signal input terminals one by one, and no short circuit occurs at all.

It is not necessary to use a stepper as an exposure device for forming the conductive film pattern 7 for anodization.
A large-scale exposure machine that can perform ordinary batch exposure is sufficient.

Although one embodiment has been described above, the present invention also includes the one configured as follows.

(1) In the above embodiment, the conductive film pattern 7 for anodic oxidation has a long main portion of the first long pattern portion 7b and the second long pattern portion 7c. Although the U-turn path is reciprocated, it may be reciprocated more than two times. Alternatively, the terminal portion 7a may be disposed near the upper side of the glass substrate 1 to reciprocate 1.5 or 2.5 reciprocations. It is also possible to In any case, the conductive film pattern 9 for forming a capacitance is formed on the main part of the conductive film pattern 7 with the interlayer insulating film 8 interposed therebetween. Figure 3 shows 1.
An example of five round trips is shown. The reference numerals are the same as in FIG.

(2) The upper part of the effective area 6 of the glass substrate 1 shown in FIG. 1 is a blank area, but the conductive film pattern 7 for anodization may be extended to this area. Also in this case, the conductive film pattern 9 for forming a capacitor is formed on the main part of the conductive film pattern 7 with the interlayer insulating film 8 interposed therebetween. FIG. 4 shows an example thereof. The reference numerals are the same as in FIG.

(3) In the above embodiment, the conductive film pattern 9 for capacitance formation is formed so as to face the conductive film pattern 7 for anodic oxidation, but instead of this, the conductive film pattern for capacitance formation is used. The film pattern 9 may not be formed. This point also applies to the above (1) and (2).

(4) In the above embodiment, the conductive film pattern 7 for anodic oxidation was taken as an example of the static electricity passage, but the conductive film pattern is not limited to the conductive film pattern for anodic oxidation, and any conductive film pattern may be separated. When formed outside the boundary line, the problem of electrostatic breakdown may be solved by taking the same measure for the conductive film pattern.

(5) In the above embodiment, one active matrix substrate is produced from one glass substrate 1, but a plurality of active matrix substrates are produced from one glass substrate. May be In this case, a long conductive film pattern may be connected to each active matrix substrate as a conductive film pattern serving as a path of static electricity, or a long conductive film may be commonly used for all or a plurality of active matrix substrates. You may connect patterns. FIG. 5 shows an example thereof. The reference numerals are the same as in FIG.

(6) In the above embodiment, the TFT is exemplified as the switching element of the image display section 2, but instead of this, a TFD (thin film diode) or an MIM (Meta) is used.
A non-linear resistance element such as an Insulator Metal) or a ZnO varistor may be used as the switching element.

(7) In the above embodiments, the active matrix substrate is targeted, but it may be applied to a simple matrix substrate.

(8) At the beginning, a description was given of a liquid crystal display device for a television display or a display monitor that replaces a CRT, but of course the present invention is not limited to this, and the present invention can be applied to any type of liquid crystal display device. You may

The above items (1) to (8) are independent of each other, and any number of these items may be combined in an appropriate number.

[0035]

According to the first aspect of the invention of the method of manufacturing a liquid crystal display device, static electricity failure is prevented when a conductive film pattern that can serve as a static electricity passage in a state connected to the image display portion is formed outside the effective area. Since a conductive film pattern having a sufficient resistance value to be formed is formed, the time constant of the conductive film pattern is made sufficiently large,
By delaying and blunting the steep electrostatic input / output waveform, suppressing the overcurrent, and lowering the voltage, at the stage before cutting the effective area from the substrate, for example, with the gate of the TFT section in the screen display section. It is possible to reliably prevent static electricity failure on the image display unit such as dielectric breakdown between the source / drain.

Further , according to the invention of claim 1 ,
Since the conductive film pattern for forming a capacitance is formed so as to face the conductive film pattern via the interlayer insulating film, the CR time constant can be further increased sufficiently by the resistance value and the electrostatic capacitance, and the static electricity defect to the image display unit can be prevented. It can be prevented more reliably. Also applied to anodic oxidation as a gate insulating film of TFT
Even if the
Can be prevented.

According to the second aspect of the present invention, since the transparent conductive film which is also used for forming the pixel electrode is formed as the conductive film pattern for forming the capacitance, it is possible to form these simultaneously and simplify the manufacturing process. Can be converted.

[0038]

[0039]

In the description (particularly the detailed description of the invention and the claims) or the drawings relating to the present case, any matters described in the beginning of the application (arbitrary elements or combinational / combinational relationships of arbitrary elements) are described. (Including), the possibility of omission is reserved. Further, regarding any matters not described in the claims but described in the detailed description of the invention or in the drawings, the possibility of addition to the claims and the possibility of modification of the description accompanying the addition are described. Withhold. That is, such omissions or additions / changes shall be treated as being directly and unambiguously guided, and it shall be declared that no new matter is added.

[Brief description of drawings]

FIG. 1 is a plan view schematically showing an active matrix substrate manufactured by a method for manufacturing a liquid crystal display device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of part of an active matrix substrate according to an embodiment.

FIG. 3 is a schematic plan view of an active matrix substrate in a modified embodiment.

FIG. 4 is a schematic plan view of an active matrix substrate according to another modified embodiment.

FIG. 5 is a schematic plan view of an active matrix substrate in still another modified embodiment.

FIG. 6 is a schematic plan view of an active matrix substrate manufactured by a method of manufacturing a liquid crystal display device according to a conventional technique.

FIG. 7 is a cross-sectional view of a part of an active matrix substrate in the related art.

FIG. 8 is a schematic plan view of an active matrix substrate disclosed in Japanese Unexamined Patent Publication.

FIG. 9 is an enlarged plan view of a main part of the active matrix substrate of the above publication.

[Explanation of symbols]

1 ... Glass substrate 2 ... Image display unit 3 ... Gate signal input terminal 4 ... Source signal input terminal 5 ... Separation boundary line 6 ... Effective area 7 ... Anodizing conductive film pattern 7a ... Terminal portion 7b ... 1st long pattern part 7c ... 2nd long pattern part 7d ... Connection pattern part 8 ... Interlayer insulating film 9 ... Conductive film pattern for capacity formation

─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Toshihiro Yamashita 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka Inside Sharp Corporation (56) Reference JP-A-6-289430 (JP, A) JP-A-6- 317810 (JP, A) JP-A-7-225393 (JP, A) JP-A-8-321620 (JP, A) JP-A-9-265110 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G02F 1/1345 G09F 9/00

Claims (2)

(57) [Claims] 1. A TFT which is an effective area on a substrate.
A main part is formed in the outer area, and one end is electrically connected to the gate of the TFT.
The gate insulation film of this TFT by connecting electrically
Forming a conductive film pattern to be anodized as
Has a resistance value sufficient to prevent static electricity failure for FT
Capacitor formation on the conductive film pattern via the interlayer insulating film
A method for manufacturing a liquid crystal display device for forming a conductive film pattern for a display. 2. A transparent conductive film pattern for forming a capacitance.
A liquid crystal display device according to claim 1, wherein a conductive film is formed.
Method.