JPH07140487A - Production of liquid crystal display device - Google Patents

Abstract

PURPOSE:To prevent a short circuit of display electrodes and auxiliary capacitance electrodes even if a pinhole exists in a dielectric layer by subjecting the surface of the transparent conductive film exposed by etchant to slight etching in stages after a stage for forming the transparent conductive film. CONSTITUTION:A gate metal is laminated on a transparent substrate and after gate electrodes and the auxiliary capacitance electrodes 12 are formed by etching the patterns of gate wirings, an insulating film 13, a-Si 14 and Si-Nx are successively laminated. In succession, a-Si 16 doped by phosphorus is laminated and is etched to allow the a-Si to remain in TFT parts, by which channel contact layers are formed. An ITO 17 as the transparent electrode material in then laminated and display electrodes 17P are formed by patterning display pixels by photoetching. Further, the ITO 17 is subjected to slight etching of 1/4 to 1/2 the film thickness of the ITO separately from patterning to the display electrodes 17P after formation of the ITO film, by which the ITO formed in the pinhole 21 is removed and the connection of the display electrodes 17P and the auxiliary capacitance electrode 13 is broken.

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 method of manufacturing a liquid crystal display device with improved defect processing.

[0002]

2. Description of the Related Art Liquid crystal display devices have advantages such as small size, thin shape, and low power consumption, and are being put to practical use in fields such as OA equipment and AV equipment. In particular, an active matrix type using a thin film transistor (hereinafter abbreviated as TFT) as a switching element can display a fine moving image,
It is used in displays for automobiles.

The active matrix type liquid crystal display device is
The structure is such that a substrate on which display electrodes connected to TFTs are arranged in a matrix and a substrate having a common electrode are attached with a liquid crystal layer interposed therebetween. The TFT is a switching element that selects an input data signal to the display electrode, and is a FET that uses amorphous silicon or polysilicon as a channel layer. The gate electrode and the drain electrode are connected to the gate line and the drain line, respectively, and the source electrode is connected to the display electrode. The display electrode and the common electrode are transparent electrodes formed of, for example, a mixture of indium oxide and tin oxide (hereinafter abbreviated as ITO).

The gate line group is line-sequentially scanned to turn on all the TFTs in the same row, and at the same time, a data signal synchronized with the scanning signal is input to the display electrodes. The potential of the common electrode is also set in synchronization with the scanning signal, and the desired effective voltage is applied to the liquid crystal layer in the gap with the display electrode to drive the liquid crystal, and the light transmittance is adjusted for each pixel. It
The driving state of the liquid crystal is held by the electric charge accumulated in the liquid crystal capacitance for one frame period when the TFT is turned off, and is rewritten by AC inversion in the next frame.

The driving state of the liquid crystal is improved by installing an auxiliary capacitance in parallel with the liquid crystal capacitance to improve the charge retention characteristic. The auxiliary capacitance is formed by setting display electrodes in common and disposing independent electrodes facing each other and setting the same potential as the common electrode, or by extending a part of the gate line and superposing them. Further, the auxiliary capacitance has a function of suppressing the shift of the display electrode potential that occurs when the TFT operates. That is, in the overlapping portion of the source and gate electrodes, which is inevitable due to the limitation of the manufacturing process, the parasitic capacitance is generated and disappears with the ON / OFF of the TFT. Therefore, by increasing the total capacitance value by adding the auxiliary capacitance in parallel, the influence of the DC component on the display electrode potential due to the parasitic capacitance is mitigated.

[0006]

By adding the auxiliary capacitance, there is a problem that both electrodes are short-circuited when there is a film defect such as a pinhole in the dielectric layer. That is, when a lower electrode, a dielectric layer, and an upper electrode are sequentially formed and foreign matter is present in the dielectric layer, the foreign matter is detached and becomes a pinhole in a photoetching process that follows. When the upper electrode is formed on this, the electrode material enters and is generated in the pinhole, and the upper and lower electrodes are short-circuited. For example, when the ITO of the upper display electrode is connected to the lower auxiliary capacitance electrode, the display electrode becomes the same potential as the common electrode or the gate electrode, and the effective voltage cannot be applied to the liquid crystal layer. Cannot be displayed.

[0007]

The present invention has been made in view of the above-mentioned problems, and includes a step of laminating a first metal on a substrate,
Patterning the first metal, forming an insulating film covering the first metal, forming a semiconductor layer on the insulating film, patterning the semiconductor layer, A step of forming a transparent conductive film on the insulating film so as to cover the semiconductor layer; a step of patterning the transparent conductive film by photoetching; and a second step on the insulating film so as to cover the transparent conductive film and the semiconductor layer. In a method of manufacturing a liquid crystal display device, which comprises a step of laminating a metal and a step of patterning the second metal, after the step of forming the transparent conductive film, the exposed transparent conductive film is replaced with the transparent conductive film. The structure is provided with a step of performing a slight etching with an etching amount of 1/4 to 1/2 of the film thickness of the film.

[0008]

In general, when a foreign substance is present in the insulating film, the foreign substance is released during the subsequent pattern formation etching or photoresist stripping to form a pinhole, and when the upper electrode material enters and forms in the pinhole, the upper and lower electrodes are formed. Leading to a short circuit. In the case of the auxiliary capacitor, the upper display electrode ITO
Is about 2000 to 4000Å, which is four times as large as the film thickness of about 500 to 1000Å. Therefore, in the pinhole, the ITO is formed thinner than the display electrode portion, especially in the side wall portion.
By performing the slight etching with an etching amount of 1/4 to 1/2 of the film thickness of, the ITO in the pinhole is removed and the connection between the display electrode and the auxiliary capacitance electrode is disconnected.

[0009]

EXAMPLES Next, examples of the present invention will be described with reference to FIGS.
It demonstrates using. In particular, the effect of the present invention is clear in the figure.
Therefore, a pinhole due to foreign matter is generated in the auxiliary capacitance section.
The figure shows the case of twisting. Gate on transparent substrate (10)
As a metal, for example, Cr is sputtered
Layered to a thickness of about 1500Å, gate wiring pattern
By etching into the gate electrode (11) and
An auxiliary capacitance electrode (12) is formed (see FIG. 1 above).
See). The auxiliary capacitance electrode (12) can be an independent electrode or a gate
It may be an electrode integrated with the line. Next, the gate insulating film and
As an insulating film (13) common to the dielectric film of the auxiliary capacitance, for example,
If SiN_X2000-4000 by plasma CVD
Laminate to a thickness of approximately Å. At this time, the auxiliary capacitance electrode (1
2) If a foreign substance (20) is attached on the insulating film (1
3) grows with inclusion of foreign matter (20). Continue to
Z-CVD for a-Si (14) about 1000Å, Si
N_XAre sequentially laminated to a thickness of about 2500Å. a-Si
(14) is the channel layer of the TFT, the uppermost SiN _XIs
Photoetch to the part corresponding to the gate electrode (11)
If left unetched, it becomes an etching stopper (15).
(For the above, refer to FIG. 2). Next, phosphorus is used to improve contact.
A-Si (hereinafter referred to as N⁺Abbreviated as a-Si
(16) by plasma CVD to a thickness of about 500Å
Stack it up. This N⁺a-Si (16) and a-Si
(14) remains in the TFT area by etching with the same mask
Channel contact layer is formed by
It Through the above steps, SiN_XAnd a-Si patterning
At the time of removal, unnecessary parts are removed and the resist film is peeled off,
Is detached, and that part becomes a pinhole (21) (below
Above, see FIG. 3).

Next, ITO (17) was used as a transparent electrode material.
Is laminated to a thickness of about 500 to 1000Å by sputtering or the like. At this time, I is also inside the pinhole (21).
TO is generated and short-circuited to the auxiliary capacitance electrode (12) below (see FIG. 4). The ITO (17) is formed by patterning display pixels by photo-etching to display electrodes (17).
P). After forming the ITO (17), apart from the patterning on the display electrode (17P), the slight etching of ITO is performed with an etching amount of ¼ of the film thickness of ITO by adjusting the etching time, for example. As a result, the ITO generated in the pinhole is removed, and the connection between the display electrode (17P) and the auxiliary capacitance electrode (12) is cut off. For example, when the film thickness of ITO (17) is 1000 Å, the ITO in the pinhole is completely removed at the same time as it is thinned to about 750 Å by the light etching (see above, FIG. 5). Since the etching amount of the slight etching is set for the purpose of removing the ITO in the pinhole without impairing the function of the display electrode (17P), it is 1/4 to 1/2 of the film thickness of the ITO (17). Has an allowable range of. In this embodiment, the insulating film (13) has a film thickness of about 2000 to 4000Å, and the ITO (17) has a film thickness of 5
Since it is set to about 100 to 1000Å, in this case, the amount of the slight etch is ¼ experimentally suitable. It should be noted that the slight etch is the display electrode (1) after the film formation of ITO (17).
7P) before or after patterning.

Then, as source / drain metal,
For example, a source electrode (18) and a drain electrode (1) are formed by stacking a two-layer film made of Al having an upper layer of 7,000 Å and Mo having a lower layer of 1000 Å by sputtering and etching the source / drain wiring pattern.
9) is formed. Finally, the center portion of N ⁺ a-Si (16) is removed by using both electrodes (18, 19) as a mask (see FIG. 6 above).

It should be noted that the slight etching of ITO (17) has the same effect even if it is performed after the source / drain pattern is formed and the display electrode is exposed.

[0013]

As is apparent from the above description, after the ITO film is formed, a slight etching of 1/4 to 1/2 of the ITO film thickness is performed, so that even if pinholes exist in the dielectric layer. , The ITO in the pinhole is removed, and the short circuit between the display electrode and the auxiliary capacitance electrode is cut off.

[Brief description of drawings]

FIG. 1 is a cross-sectional view illustrating a method of manufacturing a liquid crystal display device that is an embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating a method of manufacturing a liquid crystal display device that is an embodiment of the present invention.

FIG. 3 is a cross-sectional view illustrating a method of manufacturing a liquid crystal display device that is an embodiment of the present invention.

FIG. 4 is a cross-sectional view illustrating a method of manufacturing a liquid crystal display device that is an embodiment of the present invention.

FIG. 5 is a cross-sectional view illustrating a method of manufacturing a liquid crystal display device that is an embodiment of the present invention.

FIG. 6 is a cross-sectional view illustrating a method of manufacturing a liquid crystal display device that is an embodiment of the present invention.

[Explanation of symbols]

10 Transparent Substrate 11 Gate Electrode 12 Auxiliary Capacitance Electrode 13 Insulating Film i 14 a-Si 15 Etching Stopper 16 N ⁺ a-Si 17 ITO 18 Source Electrode 19 Drain Electrode 20 Foreign Material 21 Pinhole

Claims (2)

[Claims] 1. A step of depositing a first metal on a substrate, a step of patterning the first metal, and a step of patterning the first metal.
A step of forming an insulating film over the metal, a step of forming a semiconductor layer on the insulating film, a step of patterning the semiconductor layer, and a transparent conductive film over the insulating film and covering the semiconductor film. A step of forming, a step of patterning the transparent conductive film by photoetching, a step of laminating a second metal on the insulating film to cover the transparent conductive film and the semiconductor film, and a step of depositing the second metal. In the method for manufacturing a liquid crystal display device, which comprises a step of patterning, a step of slightly etching a surface of the transparent conductive film exposed by an etchant of the transparent conductive film is provided after the step of forming the transparent conductive film. A method for manufacturing a liquid crystal display device, comprising: 2. The method of manufacturing a liquid crystal display device according to claim 1, wherein the slight etching is performed with an etching amount of 1/4 to 1/2 of a film thickness of the transparent conductive film.