KR100213966B1 - Active matrix liquid crystal display device and its manufacturing method - Google Patents

Abstract

A method of manufacturing an active matrix liquid crystal display device according to the present invention includes the steps of forming a gate electrode branching from a gate bus line on a transparent substrate, forming a gate insulating film 23 with an organic insulating film, and forming a gate insulating film surface N _2. Forming a semiconductor layer on the gate insulating film of the gate electrode part after plasma interfacial treatment with a gas containing N, a gas containing F, and the like; and a source / drain branching from the data bus line 15 to be in contact with the semiconductor layer. After forming the electrode and forming the source / drain electrodes, the surface of the semiconductor layer is exposed to the surface of the semiconductor layer with N _2, N-containing gas, F-containing gas, etc., and then the protective layer 26 is formed of an organic insulating layer. Active to achieve high aperture ratio without sacrificing image quality and contrast by maintaining the stable characteristics of switching elements by including the forming process To provide a matrix liquid crystal display device.

Description

Manufacturing Method of Active Matrix Liquid Crystal Display and Active Matrix Liquid Crystal Display

1 is a perspective view of a basic structure showing a part of a general active matrix liquid crystal display device.

2 is a partial plan view of a conventional active matrix liquid crystal display device.

3 is a cross-sectional view of the first substrate 3 of the conventional active matrix liquid crystal display device shown by cutting the line III-III of FIG.

4 is a perspective view showing the intersection of a conventional gate bus line and data bus line.

5 is a partial plan view of an active matrix liquid crystal display of the present invention.

6 and 7 are cross-sectional views of the manufacturing process of the first substrate 3 of the active matrix liquid crystal display device of the present invention, taken along line VI-VI of FIG.

8, 9, and 10 are cross-sectional views of a first substrate (3) of an active matrix liquid crystal display device to which the present invention is applicable.

* Explanation of symbols for main parts of the drawings

DESCRIPTION OF SYMBOLS 1: Polarizing plate 22: Semiconductor layer

2: second substrate 25: ohmic contact layer

3: first substrate 26: protective film

4 pixel electrode 40 liquid crystal

15a: source electrode 8: TFT

15: data bus line 15b: drain electrode

17a: gate electrode 17: gate bus line

11, 11 ': transparent substrate 23: gate insulating film

35 anodized film 31 contact hole

36a: Gas plasma-treated interface of BCB film

36b: gas plasma-treated interface of semiconductor layer

The present invention relates to a method of manufacturing an active matrix liquid crystal display device including a thin film transistor (hereinafter referred to as TFT), and to a structure of an active matrix liquid crystal display device manufactured by the method. will be.

As shown in FIG. 1, which is a perspective view of a basic structure showing a part of a general active matrix liquid crystal display device, the liquid crystal display device has a substrate (hereinafter referred to as a first substrate) having a plurality of pixels arranged in a matrix.

Each pixel electrode 4 of the liquid crystal display of the first substrate 3 is disposed at a portion where two adjacent gate bus lines 17 and two adjacent data bus lines 15 cross each other.

The gate bus line 17 is formed in a horizontal direction, and a plurality of gate electrodes (not shown) branched from the gate bus line 17 are formed in the longitudinal direction.

On the other hand, the data bus line 15 is formed in the longitudinal direction and a plurality of source electrodes (not shown) branched from the data bus line 15 are formed in the horizontal direction.

A TFT 8 is formed at a portion where the gate bus line 17 and the data bus line 15 cross each other, and the TFT 8 is formed to be in electrical contact with the pixel electrode 4.

On the other hand, the liquid crystal display includes a substrate (hereinafter referred to as a second substrate) on which the color filter layer 38 and the common electrode 37 are formed.

The first substrate 3 and the second substrate 2 are disposed to face each other, and the liquid crystal 40 is filled between the two substrates.

The polarizing plate 1 is formed in the 1st board | substrate 3 and the 2nd board | substrate 2, respectively.

11 and 11 ', which are not described in FIG. 1, are transparent substrates.

The above components are combined to form an active matrix liquid crystal display.

With reference to the drawings will be described in detail with respect to the manufacturing method of the first substrate (3) related to the object of the present invention among the various components as described above.

2 is a partial plan view of a conventional active matrix liquid crystal display device.

3 is a cross-sectional view of the first substrate 3 taken along the line III-III of FIG.

As can be seen from FIG. 3, the configuration of the first substrate 3 of the active matrix liquid crystal display device manufactured by the conventional manufacturing method is as follows.

A gate bus line 17 formed laterally on the transparent substrate 11 and a gate electrode 17a branching in the longitudinal direction from the gate bus line 17 are formed.

The gate electrode 17a is anodized to improve insulation and prevent hillocks.

A gate insulating film 23 made of an inorganic film such as silicon nitride (SiNx) or silicon oxide (SiOx) is formed on the transparent substrate 11 on which the gate electrode 17a is formed.

A semiconductor layer 22 such as amorphous silicon (hereinafter referred to as a-Si) is formed on the gate insulating film 23 in the gate electrode 17a portion.

An ohmic contact layer 25 is formed on the semiconductor layer 22 such as a-Si.

A source electrode 15a is formed by branching in the longitudinal direction from the source bus line 15 and the source bus line 15 formed in the longitudinal direction, and the drain electrode 15b is spaced apart from the source electrode 15a at a predetermined interval. Is formed.

The source electrode 15a and the drain electrode 15b are formed to contact the ohmic contact layer 25.

A protective film 26 made of an inorganic film such as silicon nitride (SiNx) is formed to cover the source drain electrode and the like, and the ITO (transparent conductive film contacting the drain electrode 15b through the contact hole 31 of the drain electrode part) is formed. An indium tin oxide film is formed on the passivation film 26 to form the pixel electrode 4.

However, the manufacturing method of the active matrix liquid crystal display device manufactured by manufacturing the first substrate 3 by the conventional manufacturing method as described above

First, since the data bus line 15 crosses the gate bus line 17 as it is along the line step at the intersection with the gate bus line 17, the step of the data bus line 15 In this case, the data bus line may be disconnected or the data bus line 15 may be shorted with the gate bus line 17.

Second, the pixel bus 4 formed on the passivation layer 26 made of an inorganic film such as SiNx, SiOx, or the like to realize a high aperture ratio by the conventional manufacturing method, as shown in Fig. 5, the gate bus line 17 and the deata bus line If the pixel electrode 4 overlaps the gate bus line 17 and the data bus line 15, a problem occurs that the image quality and contrast of the pixel are deteriorated.

The deterioration of the image quality and contrast may be achieved by forming a protective film 26 made of an inorganic film such as SiNx, SiOx, and the like, and overlapping the pixel electrode on the protective film 26 with the gate bus line 17 and the data bus line 15. This is because the alignment states of the liquid crystal molecules of the stepped portions are different due to the poor rubbing of the stepped portions of the gate busian 17 and the data bus line 15 in the rubbing process of the alignment film which is subsequently performed when formed.

The problem of the conventional manufacturing method of the liquid crystal display device, that is, the problem of poor rubbing, short defect, and small aperture ratio of the alignment layer can be solved to some extent by configuring the gate insulating film 23 and the protective film 26 with an organic insulating film.

However, by using the organic insulating film, charge traps of charge are generated at the interface portion where the semiconductor layer 22 and the organic insulating film of the TFT come into contact with each other, thereby shifting the ON characteristic of the TFT by a certain amount, thereby improving stability of the TFT. There is a problem falling.

In addition, since the organic insulating film has a weak bonding force with another material, for example, a metal, an ITO film, or the like, many defects occur when the other material is deposited or patterned on the organic insulating film. An object of the present invention is to prevent the data bus line from being disconnected or the data bus line 15 and the gate bus line 17 from shorting at the intersection portion of the gate bus line 17 and the data bus line 15, and the like. SUMMARY OF THE INVENTION An object of the present invention is to provide a liquid crystal display device having an aperture ratio, in particular, switching elements such as TFTs having stable characteristics.

In the active matrix liquid crystal display device of the present invention, in order to achieve the above object, the gate insulating film 23 is formed of an organic insulating film,

After the plasma interfacial treatment of the gate insulating film surface with a gas containing N ₂ N, a gas containing F, and the like, a semiconductor layer is formed on the gate insulating film of the gate electrode portion,

Forming a source / drain electrode branching from the data bus line 15 to be in contact with the semiconductor layer,

The first substrate 3 is configured by forming a protective film 26 using an organic insulating film after plasma interfacial treatment with a gas containing N ₂ N, a gas containing F, or the like on the surface of the semiconductor layer.

As the organic insulating layer, Benzocyclobytene (BCB), F-added parerin, and the like, and PFCB (Perfluorocyclobutane) not mentioned in Table 1-1, are used.

These organic substances may react to light depending on the structure of additives or similar organic substances.

Since the organic insulating layer has a good leveling characteristic that exceeds the step, it is possible to flatten the surface of the substrate of the liquid crystal display device, reduce the misalignment of the liquid crystal due to the step, and the organic insulating layer has a lower relative dielectric constant than the inorganic insulating layer. Even when a pixel electrode is formed on the organic insulating layer to overlap a line such as a data bus line to form a liquid crystal display device having a high aperture ratio, voltage distortion due to parasitic capacitance does not occur at the portion where the pixel electrode and the line overlap. Therefore, it is possible to provide a liquid crystal display device in which a defect such as screen flicker does not occur.

In addition, when the organic insulating film is used as the data insulating film 23, since no step difference occurs, a defect in which the data bus line 17 is disconnected or shorted at a portion where the gate bus line 15 and the data bus line 17 cross each other is eliminated. There is an advantage that does not occur.

Hereinafter, a method of manufacturing a first substrate of an active matrix liquid crystal display device will be described in detail with reference to BCB including a Si—O bonding structure among organic insulating films having a relative dielectric constant of 3.0 or less.

Example 1

Embodiment 1 of the present invention describes a method of manufacturing an active matrix liquid crystal display device by a process sectional view of FIG. 6, which is taken along line VI-VI of FIG. 5, which is a plan view of the active matrix liquid crystal display device of the present invention.

Anodized metal (Al, AlTa, AlMo, Ta, Ti) or Cr metal without anodization is deposited on the transparent substrate 11, a photoresist is applied on the metal film, and the photoresist is formed in a predetermined pattern. The metal film is etched by wet etching or the like according to the developed pattern to form a gate electrode 17a branching from the gate bus line and the gate bus line (Fig. 6A).

The photoresist left on the substrate is removed by a separate process.

Subsequently, when the metal film is an anodized metal, an anodization film 35 is formed on the gate bus line 17 and the gate electrode 17a to improve insulation and prevent hillock (FIG. 6B).

Subsequently to the above process, BCB serving as the gate insulating film 23 is applied, and the surface of the BCB is treated with a plasma interface 36a with a gas containing NN, a gas containing F, or the like (FIG. 6C).

The gate insulating film 23 is formed of an organic insulating film including a bonding structure of Si and O, and the surface is interfacial so that a Si-N (silicon nitride) or Si-F (silicon fluoride) bond is formed in a subsequent process. The characteristics of the TFT can be stabilized by preventing charge trapping from occurring between the semiconductor layer and the organic insulating layer.

In addition, when a conventional inorganic insulating film is used, disconnection or short defect of the data bus line 15 occurring at the intersection of the gate bus line 17 and the data bus line 15 is eliminated.

Subsequently, the a-Si layer serving as the semiconductor layer 22 and the n + -type a-Si layer serving as the ohmic contact layer 25 are successively deposited, and then a photoresist is applied on the n + -type a-Si layer. Is developed to a predetermined pattern, and the ohmic contact layer 25 and the semiconductor layer 22 are formed by simultaneously etching the n + type a-Si layer and the a-Si layer according to the developed pattern (Fig. 6D). .

The photoresist left on the substrate is removed by a separate process.

Subsequently, an Al metal film or the like is deposited on the entire surface of the substrate by a sputtering method, a photoresist is applied on the metal film, the photoresist is deposited to a predetermined pattern, and the metal film is etched according to the developed pattern to signal lines. A data bus line 15 functioning as a source, a source electrode 15a branched from the data bus line 15, and a drain electrode 15b functioning as output terminals are formed. Next, using the source electrode and the drain electrode as a mask, the center portion of the ohmic contact layer 25 is etched so that the ohmic contact layer 25 is separated on both sides (Fig. 6E).

Subsequently, after the plasma interface 36b is treated with a gas including NN, a gas containing F, and the like, the BCB serving as the protective layer 26 is exposed to the surface of the semiconductor layer exposed by etching of the central portion of the ohmic contact layer 25. It apply | coats (FIG. 6f).

As described above, when the plasma interfaces 36a and 36b are treated with a gas containing NN, a gas containing F, or the like on the surface of the organic insulating film serving as the gate insulating film 23 or the exposed semiconductor layer, the baby plasma surface treatment is performed. As the combined energy of the interface is increased, charge traps of charges do not occur at the interface of the semiconductor layer 22, so that the TFT is stabilized and other materials such as metal, ITO film, Even if the a-Si layer or the like is deposited or patterned, no peeling or patterning failure of the film occurs.

Therefore, by using the organic insulating film as the gate insulating film 23 and the protective film 26 and interfacing the film formed as necessary, the data bus line 15 is formed at the intersection portion of the gate bus line 17 and the data bus line 15 and the like. It is possible to prevent disconnection or short circuit between the data bus line 15 and the gate bus line 17, to have a high aperture ratio, and in particular, to ensure that switching elements such as TFTs have stable characteristics.

Next, a photoresist is applied on the passivation layer 26 made of the organic insulating layer, and the photoresist is developed to have a predetermined pattern, and the passivation layer 26 is etched according to the developed pattern to contact the drain electrode part ( 31) (Fig. 6g).

The photoresist left on the substrate is removed by a separate process.

Subsequently, an indium tin oxide (ITO) film is deposited on the protective layer 26 having the contact hole by sputtering, a photoresist is applied on the ITO film, and the photoresist is developed to have a predetermined pattern. In this manner, the ITO film is etched to form the pixel electrode 4 so as to overlap the data bus line as shown in FIG. 5 (FIG. 6H).

The photoresist left on the substrate is removed by a separate process.

In FIG. 5, which shows a partial plan view of the active matrix liquid crystal display device of the present invention, the pixel electrode 4 overlaps only the data bus line 15, but is selectively applied to other portions, that is, the gate bus line 17 and the TFT portion. By overlapping, the aperture ratio can be maximized.

In general, the pixel electrode portion overlapping the gate bus line 17 is a portion of the storage capacitor nationwide, but the description of the formation process of the storage capacitor electrode is omitted.

Although the present invention has only been applied to the IOP (ITO On Passivation) structure in which the pixel electrode is formed on the passivation layer, the present invention can be applied regardless of the position where the pixel electrode is formed.

For example, a pixel electrode may be formed before or after forming the semiconductor layer-ohmic contact layer (FIG. 7).

The common electrode may be formed on the same substrate on which the pixel electrode is formed, and the common electrode may be formed on a substrate facing the substrate on which the pixel electrode is formed.

The structure in which the common electrode and the pixel electrode are formed on the same substrate, that is, in-plane switching (IPS) mode is advantageous for implementing a wide viewing angle.

The present invention can also be applied to a liquid crystal display device in which the first substrate has the structures shown in FIG. 8, FIG. 9, and FIG.

Claims (20)

A switching element having a gate electrode branched from the gate bus line, a gate insulating film, a semiconductor layer with a portion of the surface exposed, an ohmic contact layer, and a source / drain electrode branched from the data bus line; A manufacturing method of a liquid crystal display device comprising a protective film covering the switching element; Forming the gate insulating film as an organic insulating film, subjecting the surface of the organic insulating film to an interfacial treatment, forming the switching element, and interfacing the exposed semiconductor layer surface of the switching element; And forming a protective film covering the interface-treated switching element as an organic insulating film. The method of claim 1; And exposing the gate insulating film surface and the exposed semiconductor layer surface of the switching element to a gas plasma to perform interfacial treatment. The method of claim 2; The gas plasma may be any one selected from a gas containing N ₂ N and a gas containing F. The method of claim 1; And forming a pixel electrode on the passivation layer so as to selectively overlap the data bus line. The method of claim 1; And forming a pixel electrode on the passivation layer so as to selectively overlap with the neighboring gate bus line and the data bus line of the gate bus line. The method of claim 1; And forming a pixel electrode after the semiconductor layer is formed. The method of claim 1; And further forming a pixel electrode before forming the semiconductor layer. 8. A compound according to any one of the preceding claims; The organic insulating film is a manufacturing method of a liquid crystal display device comprising a Si-O bond structure. 8. A compound according to any one of the preceding claims; And said organic insulating film has a relative dielectric constant of 3.0 or less. 8. A compound according to any one of the preceding claims; And the organic insulating layer is any one selected from BCB and PFCB. A switching element having a gate electrode branched from the gate bus line, a gate insulating film, a semiconductor layer with a portion of the surface exposed, an ohmic contact layer, and a source / drain electrode branched from the data bus line; A liquid crystal display device comprising: a protective film covering the switching element; And the gate insulating film is formed of an organic insulating film, the surface of the organic insulating film is interfacially treated, the exposed semiconductor layer surface of the switching element is interfacially treated, and the protective film is formed of an organic insulating film. The method of claim 11; And the surface of the gate insulating layer and the exposed semiconductor layer surface of the switching element are exposed to a gas plasma to perform an interface treatment. The method of claim 12; And the gas plasma uses any one selected from a gas containing N ₂ N and a gas containing F. The method of claim 11; And a pixel electrode is further formed on the passivation layer so as to selectively overlap the data bus line. The method of claim 11; And a pixel electrode is further formed on the passivation layer so as to selectively overlap the gate bus line and the data bus line adjacent to the gate bus line. The method of claim 11; And a pixel electrode is further added after the semiconductor layer is formed. The method of claim 11; And a pixel electrode is added before forming the semiconductor layer. The method according to any one of claims 11 to 17; And the organic insulating layer includes a Si—O bond structure. The method according to any one of claims 11 to 17; The organic insulating film has a relative dielectric constant of 3.0 or less. The method according to any one of claims 11 to 17; And the organic insulating layer is any one selected from BCB and PFCB.