JP2000056284A - Manufacturing method of liquid crystal display device - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To reduce non-uniformity of a processing line width in a substrate surface during wet etching. SOLUTION: The present invention relates to a Mo / A material which is used as a material of a signal line of a liquid crystal display device, a source electrode and a drain electrode of a pixel TFT.
After forming the l / Mo laminated film 9, a resist pattern 10 is formed on the upper surface thereof, and wet etching is performed using an etching solution containing a long-chain alkyl ester. Thereby, even if the resist pattern 10 is softened during the etching and the lower surface side of the resist pattern 10 is eroded by the etching, the eroded area can be covered with the resist pattern 10. Therefore, there is no risk of being excessively etched.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an etching step which is one of manufacturing steps of a liquid crystal display device, and particularly to a case where wet etching is performed.

[0002]

2. Description of the Related Art In recent years, an active matrix type liquid crystal display device is often used as a display device of various portable devices such as a notebook computer for reasons of high image quality, thinness, light weight and low power consumption. Was. In this type of active matrix liquid crystal display device, a thin film transistor (TFT) is used as a switching element for pixel display.
Film Transistor) is generally used.

A liquid crystal display device has a structure in which a liquid crystal material is sealed between a pixel array substrate and a counter substrate. The pixel array substrate has a gate electrode and a scanning line (not shown), a gate insulating film, an a-Si film serving as a channel layer, an etching stopper layer,
A pixel electrode, a source electrode, a drain electrode, a signal line, and a passivation layer formed of a low-resistance Si layer, ITO (Indium Tin Oxide), or the like.

When processing an etching stopper layer, a gate line, a signal line, a pixel electrode layer, and a contact hole on a pixel array substrate, a wet etching method using a chemical is often employed.

[0005]

However, when wet etching is performed, the etching progresses isotropically, so that a portion of the lower surface of the photoresist is shaved and an undercut region is generated. Further, in general, it is difficult to uniformly supply an etchant within a substrate surface of a large-sized substrate such as used in a liquid crystal display device, and an etching rate varies depending on a location.

For this reason, it is necessary to perform etching in accordance with the portion of the substrate surface where the progress of etching is the slowest, and in places where the etching rate is high in the substrate surface, the etching proceeds excessively and the line of the resist The line width of the completed pattern with respect to the width becomes too thin. That is, the line width of the completed pattern varies within the substrate surface.

The difference between the line width of the pattern and the line width of the resist is called a conversion difference. When designing a photomask, it is necessary to design a pattern layout in consideration of the conversion difference and the in-plane non-uniformity of the conversion difference, and a useless space is generated in the layout.

The present invention has been made in view of the above points, and an object of the present invention is to provide a method of manufacturing a liquid crystal display device capable of reducing in-plane nonuniformity of a processing line width during wet etching. It is in.

[0009]

According to a first aspect of the present invention, there is provided a method of manufacturing a liquid crystal display device in which a pattern is formed by a wet etching process using a resist as a mask. As an etchant used in the process, an etchant containing a long-chain alkyl ester is used.

According to a second aspect of the present invention, there is provided a method of manufacturing a liquid crystal display device in which a signal line and a scanning line are arranged in a row and a thin film transistor is formed near each intersection of the signal line and the scanning line. A source electrode and a drain electrode are formed by wet etching using a resist as a mask, and an etchant containing a long-chain alkyl ester is used as an etchant used in the wet etch process.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a method for manufacturing a liquid crystal display device according to the present invention will be specifically described with reference to the drawings. The embodiment described below is characterized in that when forming a source electrode, a drain electrode and a signal line by wet etching, an etching solution containing a long-chain alkyl ester is used.

FIGS. 1 and 2 are process diagrams showing a manufacturing process of a liquid crystal display device according to the present invention, and show cross-sectional views of an inverted stagger type array substrate for a liquid crystal display device.

First, as shown in FIG. 1A, a metal or alloy thin film is formed on one main surface of a glass substrate 1, which is a light-transmitting insulating substrate, and this thin film is etched into a predetermined pattern. Processing is performed to form the gate electrode 2 and a scanning electrode (not shown).

Next, as shown in FIG. 1B, a gate insulating film 3 made of silicon oxide or the like is formed on the gate electrode 2 by a plasma CVD method. Next, as shown in FIG. 2C, after the a-Si film 4 serving as a channel layer and the etching stopper layer 5 are continuously formed by a plasma CVD method, only the etching stopper layer 5 is processed to form an island shape. leave.

Next, as shown in FIG.
After forming the layer 6, the low-resistance Si layer 6 and the a-Si film 4 are etched into the same shape. Next, after ITO is formed by a sputtering method, the ITO is etched into a predetermined pattern to form the pixel electrode 7. Next, a contact hole is formed on the gate insulating film 3 using a buffered hydrofluoric acid solution BHF, and a signal can be externally applied to the scanning electrode through the contact hole.

Next, as shown in FIG. 2A, three layers of Mo / Al / Mo 9 are continuously formed by sputtering, and a predetermined resist pattern 10 is formed on the upper surface by photolithography. Form.

Next, a part of the Mo / Al / Mo laminated film 9 is etched using the resist pattern 10 as a mask. As a photoresist material used as a mask at the time of etching, a mixture of orthodiazonaphthoquinone-5-sulfonic acid ester and a novolak resin is often used. It is known that such resins are generally plasticized by adding long-chain alkyl esters. Materials exhibiting such effects are called plasticizers.

Therefore, in this embodiment, for example, 10% by volume of dimethyl phthalate is added as a plasticizer to a solution having a volume ratio of phosphoric acid: nitric acid: acetic acid: water of 16: 1: 2: 1. Etching is performed with an etchant.

It is sufficient that the plasticizer contains a long-chain alkyl ester, such as phthalic acid ester, adipic acid ester, azelaic acid ester, trimellitic acid ester, sebacic acid ester, phosphate ester, glycol ester, epoxy ester Any of fatty acid ester, butyl lauryl, and butyl benzyl, or a mixture thereof may be used.

By etching using an etching solution containing such a plasticizer, predetermined portions of the Mo / Al / Mo laminated film 9 are removed by etching, and as shown in FIG. 11, a drain electrode 12, and a signal line (not shown) are formed.

The thickness of the Mo / Al / Mo laminated film 9 is, for example, 1000 angstroms, 5000 angstroms, and 1000 angstroms, respectively. In this case, the distribution of the etching rate in the plane of the substrate was about ± 30%. As a material for the photoresist, Ship
ley's AZ1350 was used.

Next, as shown in FIG.
After forming a film of SiN 13 as a material of the passivation layer by CVD, etching is performed to complete the pixel array substrate. Next, the pixel array substrate is opposed to the opposing substrate 14 on which a color filter or the like is formed, and a liquid crystal material 15 is sealed therebetween and bonded.

FIG. 3 is a diagram for explaining the steps of FIGS. 2A and 2B in detail. FIG. 3A shows an etching target film to be etched, that is, the Mo film shown in FIG.
A state where a resist pattern 10 is formed on the upper surface of the / Al / Mo laminated film 9 is shown. FIG. 3B shows a state immediately after wet etching is started using the above-described etching solution containing a plasticizer.

As shown in FIG. 3B, since the wet etching is isotropically performed, not only the portion where the resist pattern 10 is not adhered but also the lateral direction, that is, the lower surface side of the resist pattern 10 is used. Some parts will be etched.

However, since the etchant of this embodiment contains a plasticizer made of the above-described material,
The resist softens during etching. For this reason, FIG.
As shown in (c), as the etching progresses,
The resist pattern 10 hangs down along the etching surface to cover the etching surface. Then, at the end of the etching, the entire etched surface at the end of the resist is covered with the resist. Therefore, there is no possibility that the film to be etched is excessively etched, and the signal line and the source electrode and the drain electrode of the thin film transistor can be accurately formed as designed.

As a result, the conversion difference, which is the line width difference of the completed pattern with respect to the resist pattern, is reduced and the variation in the conversion difference is reduced as compared with the related art.

FIG. 4 is a diagram showing the conversion difference of the present embodiment and the conventional conversion difference. As shown, according to the present embodiment, the conversion difference is equal to or less than a quarter of the conventional value.

In the above-described embodiment, an example has been described in which an etching solution containing a plasticizer is used to form a signal line and a source electrode and a drain electrode of a thin film transistor. When forming, the above-mentioned etching solution may be used.

[0029]

As described above in detail, according to the present invention, since the wet etching is performed using the etching solution containing the long-chain alkyl ester, the resist can be softened during the etching, and the softened resist can be obtained. The resist can cover the etched surface near the edge of the resist. Therefore, there is no possibility that the surface to be etched is etched more than necessary, the variation in pattern line width during wet etching can be reduced, and a pattern as designed can be formed.

[Brief description of the drawings]

FIG. 1 is a view showing a manufacturing process of an embodiment of a liquid crystal display device.

FIG. 2 is a view showing a manufacturing process following FIG. 1;

FIG. 3 is a diagram for explaining the steps of FIGS. 2A and 2B in detail.

FIG. 4 is a diagram showing a conversion difference of one embodiment and a conventional conversion difference.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Glass substrate 2 Gate electrode 3 Gate insulating film 4 a-Si film 5 Etching stopper layer 6 Low resistance Si layer 7 Pixel electrode 8 Contact hole 9 Mo / Al / Mo laminated film 10 Resist pattern 11 Source electrode 12 Drain electrode

Claims (3)

[Claims] 1. A method for manufacturing a liquid crystal display device in which a pattern is formed by a wet etching process using a resist as a mask, wherein an etching solution containing a long-chain alkyl ester is used as an etching solution used in the wet etching process. A method for manufacturing a liquid crystal display device characterized by the above-mentioned. 2. A method for manufacturing a liquid crystal display device in which a signal line and a scanning line are arranged in a row and a thin film transistor is formed near each intersection of the signal line and the scanning line, wherein at least the signal line and a source electrode and a drain of the thin film transistor are provided. A liquid-crystal display device, comprising: a wet etching step of forming an electrode by wet etching using a resist as a mask; and using an etching solution containing a long-chain alkyl ester as an etching solution used in the wet etching process. Manufacturing method. 3. The etching solution according to claim 1, wherein the etching solution is a phthalate ester,
Adipates, azelates, trimellites, sebacates, phosphates,
3. The method for manufacturing a liquid crystal display device according to claim 1, wherein the liquid crystal display device is any one of a glycol ester, an epoxy fatty acid ester, butyl lauryl, and butyl benzyl, or a mixture thereof.