KR100229612B1 - 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 TFT 8 as a switching element on a transparent substrate and forming an inorganic insulating film such as SiNx and SiOx on the TFT 8 and an inorganic insulating film such as BCB A step of forming a protective film 26 having an insulating film of a two-layer structure by successively layering organic insulating films 26a and 26b and a step of forming a pixel electrode so as to overlap the source bus line and the like on the protective film 26, It is possible to manufacture an active matrix liquid crystal display device having a high aperture ratio in which stable characteristics are obtained and no flicker occurs on the screen.

Description

Method for manufacturing active matrix liquid crystal display device and active matrix liquid crystal display device

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

FIG. 2 is a plan view of a part of a conventional active matrix liquid crystal display; FIG.

3 is a cross-sectional view of a first substrate 3 of a conventional active matrix liquid crystal display device in which a line III-III in FIG. 2 is cut.

FIG. 4 is a partial plan view of the active matrix liquid crystal display device of the present invention. FIG.

5 is a cross-sectional view showing the manufacturing process of the first substrate 3 of the active matrix liquid crystal display device of the present invention, which is obtained by cutting the line V-V in FIG.

Description of the Related Art

(1) Polarizing plate (22) Semiconductor layer

(2) The ohmic contact layer of the second substrate 25

(3) Protective film of the first substrate 26

(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) Anodic oxide film (31) Contact hole

(26a) The inorganic insulating film constituting a part of the protective film (26)

(26b) The organic insulating film constituting a part of the protective film 26

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

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

Each of the pixel electrodes 4 of the liquid crystal display part of the first substrate 3 is arranged at a portion where two adjacent gate bus lines 17 and two adjacent data bus lines 15 are crossed.

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 intersect and the TFT 8 is formed to be in electrical contact with the pixel electrode 4. [

On the other hand, the liquid crystal display device has a substrate (hereinafter referred to as a second substrate) on which a color filter layer 36 and a common electrode 37 are formed.

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

A polarizing plate 1 is formed on the first substrate 3 and the second substrate 2, respectively.

(11) and (11 ') not described in the first figure are transparent substrates.

The above-described various components are combined to complete an active matrix liquid crystal display device.

A method of manufacturing the first substrate 3, which is related to the object of the present invention, will be described in detail with reference to the drawings.

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

FIG. 3 is a cross-sectional view of the first substrate 3 cut along the line III-III in FIG. 2.

As shown in FIG. 3, the structure 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 in a lateral direction on the transparent substrate 11 and a gate electrode 17a branched in the longitudinal direction in the gate bus line 17 are formed.

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

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 of the gate electrode 17a.

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

The source bus line 15 formed in the longitudinal direction and the source bus line 15 are laterally branched to form the source electrode 15a and the drain electrode 15b is formed at a predetermined distance from the source electrode 15a .

The source electrode 15a and the drain electrode 15b are formed to be in contact with 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 and drain electrodes and the like and a transparent conductive film ITO Indium Tin Oxide (ITO) film is formed on the protective film 26 to constitute the pixel electrode 4.

In the active matrix liquid crystal display device manufacturing method in which the first substrate 3 is fabricated by the conventional manufacturing method as described above, an inorganic insulating film such as SiNx or SiOx is used as the protective film 26, A line and a TFT are formed so as to be stepped, and a pixel electrode is formed on the step.

The stepped line and the stepped TFT cause various problems in the active matrix liquid crystal display device.

Particularly, in forming the alignment layer after forming the pixel electrode, rubbing failure occurs in the stepped portion and the alignment state of the liquid crystal is different, which causes deterioration of the quality and contrast of the liquid crystal display device.

Also, when the organic insulating film is used as the protective film 26, a charge trap of charge is generated at the interface portion between the semiconductor layer 22 of the TFT and the organic insulating film, and the ON characteristic of the TFT is shifted by a predetermined amount The stability of the TFT is deteriorated.

In order to solve the above problems, the present invention provides an organic insulating film such as SiNx and SiOx and an organic insulating film having a relative dielectric constant of 3.0 or less as shown in Table 1-1, that is, benzocyclobutene (BCB) (PFCB) or the like not mentioned in Table 1-1 is continuously layered to form a protective film 26 with a double insulating film.

These organic materials can react to light depending on the structure of additives or similar organic materials.

The organic insulating film has a leveling characteristic that is superior to the level difference in level, so that the surface of the substrate of the liquid crystal display device can be planarized and the defective orientation of the liquid crystal due to the step can be reduced. A pixel electrode is formed on the organic insulating layer so as to overlap with a line such as a data bus line, thereby forming a liquid crystal display device having a high aperture ratio. In addition, a voltage distortion phenomenon due to the generation of parasitic capacitance It is possible to provide a liquid crystal display device in which defects such as screen flickering do not occur.

In the present invention, the protective film 26 is formed as a two-layer structure by laminating the protective film 26 with an inorganic insulating film without forming only the organic insulating film. This prevents charge traps from occurring at the interface between the semiconductor layer and the organic insulating film, In order to stabilize TFT characteristics.

The structure of the first substrate of the liquid crystal display of the present invention includes a substrate, a TFT which is a switching element formed on the substrate, that is, a gate electrode 17a branched from the gate bus line 17 and a gate insulating film 23 A semiconductor layer 22 formed on the gate insulating film of the gate electrode 17a and an ohmic contact layer 25 formed on both sides of the semiconductor layer and a data bus line 15 contacted with the ohmic contact layer. The protective film 26 formed of one source / drain electrode and covering the switching element is formed to have a structure in which at least one layer of an inorganic insulating film and an organic insulating film are stacked.

Hereinafter, a method for manufacturing a first substrate of an active matrix liquid crystal display device will be described in detail with reference to bcb as an organic insulating film having a relative dielectric constant of 3.0 or less.

[Example 1]

Embodiment 1 of the present invention describes a manufacturing method of an active matrix liquid crystal display device by a process sectional view of FIG. 5, which is a sectional view taken along line V-V of FIG. 4, which is a plan view of an active matrix liquid crystal display device of the present invention.

Anodic oxidizable metal (Al, AlTa, AlMo, Ta, Ti) or Cr metal which does not cause anodization is deposited on the transparent substrate 11, a photoresist is coated on the metal film, And the metal film is etched by wet etching or the like in accordance with the developed pattern to form a gate electrode 17a that branches off from the gate bus line and the gate bus line (FIG. 5A).

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

Next, in the case where the metal film is an anodic oxidizable metal, an anodic oxide film 35 is formed on the gate bus line 17 and the gate electrode 17a (FIG. 5b) to improve insulation and prevent hillocks.

An a-Si layer to be the semiconductor layer 22 and an n + -type a-Si layer to be the ohmic contact layer 25 are formed on the inorganic insulating film by depositing an inorganic insulating film such as SiNx or SiOx which becomes the gate insulating film 23, Layers are continuously deposited (FIG. 5C).

Then, a photoresist is coated on the n + -type a-Si layer, the photoresist is developed to have a predetermined pattern, and the n + -type a-Si layer and the a-Si layer are simultaneously etched according to the developed pattern, The semiconductor layer 25 and the semiconductor layer 22 are formed (FIG. 5D).

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

Then, an Al metal film or the like is deposited on the entire surface of the substrate by sputtering, a photoresist is coated on the metal film, the photoresist is developed so as to have a predetermined pattern, the metal film is etched according to the developed pattern, A source electrode 15a branched from the data bus line 15 and a drain electrode 15b functioning as an output terminal are formed. Then, the center portion of the ohmic contact layer 25 is etched using the source electrode and the drain electrode as masks to separate the ohmic contact layer 25 on both sides (FIG. 5E)

Then, an inorganic insulating film 26a of SiNx, SiOx, or the like, which becomes the protective film 26, is deposited to a thickness of 500 to 2000 angstroms or more and further evaporated. An organic insulating film 26b such as BCB containing the Si-O bond structure shown in Table 1-1 is coated on the deposited inorganic insulating film by spin coating to a thickness of 1 탆 or more (see FIG. 5f)

In the case where the semiconductor layer 22 and the BCB film 26b are in direct contact with each other, the BCB film is peeled off because the bonding strength between the semiconductor layer and the bcb film is low, and the peeled BCB layer and the semiconductor layer 22 A charge trap of charge is generated in the interface portion where the TFTs are in contact with each other, and the ON characteristics of the TFT are shifted by a predetermined amount. As a result, the protective film 26a made of an inorganic film is applied as described above in order to prevent the stability of the TFT.

The inorganic insulating film may be formed of a single layer or a laminate of SiOx and SiNx.

As a result, the protective film 26 is double-layered with the inorganic insulating film 26a and the BCB film 26b to form the first substrate 3 shown in FIG. 1, It is possible to planarize the surface of the first substrate and fully utilize the advantage of the BCB film having a lower relative dielectric constant than the inorganic insulating film to increase the aperture ratio of the liquid crystal display device.

Even when a liquid crystal display device having a high aperture ratio is formed by forming the BCB film 26B having a lower relative dielectric constant than the inorganic insulating film so as to overlap the line of the data bus line 15 or the like so as to overlap with the line of the data bus line 15, The voltage distortion does not occur due to the generation of the parasitic capacitance in the overlapped portion, so that the defects such as the screen flicker do not occur.

Subsequently, a photoresist is coated on the BCB film 26b, the photoresist is developed to have a predetermined pattern, and the protective film 26 (26a, 26b) is etched according to the developed pattern, (See Fig. 5g)

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

Next, an ITO (Indium Tin Oxide) film is deposited on the protective film 26 on which the contact hole is formed by sputtering, a photoresist is coated on the ITO film, the photoresist is developed to have a predetermined pattern, The ITO film is etched to form the pixel electrode 4 so as to overlap the data bus line as shown in FIG. 4 (5h)

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

Although the pixel electrode 4 is superimposed on only the data bus line 15 in the fourth figure showing a partial plan view of the active matrix liquid crystal display device of the present invention, the other part, that is, the gate bus line 17, So that the aperture ratio can be maximized.

Generally, the portion of the pixel electrode overlapped with the gate bus line 17 becomes a storage capacitor electrode, but a description of the formation process of the storage capacitor electrode is omitted.

A stagger type TFT shown in Fig. 6 (a) or a coplanar type TFT shown in Fig. 6 (b), an organic insulating film having a relative dielectric constant of 3.0 or less is laminated on an inorganic insulating film to form a protective film 26 ).

Although the present invention is applied to an IOP (on-off passivation) structure in which a pixel electrode is formed on a protective film, the present invention can be applied regardless of the position where the pixel electrode is formed.

For example, the pixel electrode may be formed before or after the semiconductor layer-ohmic contact layer is formed.

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 the substrate opposing the substrate on which the pixel electrode is formed.

That is, the IPS (In-Plane Switching) mode is advantageous in realizing a wide viewing angle, because the common electrode and the pixel electrode are formed on the same substrate.

The effect of the above embodiment is that the inorganic insulating film and the organic insulating film having the relative dielectric constant of 3.0 or less, that is, the laminated structure of benzocyclobutene (BCB), F-doped Parelline PFCB (Perfluorocyclobutane) It is possible to further flatten the surface step of the active matrix liquid crystal display device and to reduce the orientation deficiency of the liquid crystal. Therefore, it is possible to prevent the defective image quality of the liquid crystal display device due to the domain development and the like, and to improve the yield as much.

In addition, it is possible to provide an active matrix liquid crystal display device having a stable characteristic of a TFT and a high aperture ratio in which flickering of a screen does not occur.

Claims (20)

A method of manufacturing a liquid crystal display device including a gate electrode, a semiconductor layer, an ohmic contact layer, a source / drain electrode branched from a data bus line, a protective film, and a pixel electrode, Wherein the protective film is at least one selected from the group consisting of F-added polyimide, Teflon, cytochrome, fluorinated polyaryl ether, F-parylene, PFCB and SI- Wherein the first electrode and the second electrode are laminated on the insulating film. The manufacturing method of a liquid crystal display device according to claim 1, wherein the inorganic insulating film is formed to have at least one layer with a thickness of about 500 to 2000 ANGSTROM, and the organic insulating film has a thickness of 1 mu m or more. The method of claim 1, wherein the pixel electrode is formed on the protective film so as to selectively overlap the data bus line. The method of claim 1, wherein the pixel electrode is formed on the passivation layer so as to selectively overlap the gate bus line adjacent to the gate bus line and the data bus line. The method of manufacturing a liquid crystal display device according to claim 1, wherein the pixel electrode is formed before forming the semiconductor layer. The method of manufacturing a liquid crystal display device according to claim 1, wherein the pixel electrode is formed after the semiconductor layer is formed. The manufacturing method of a liquid crystal display device according to claim 1, wherein an etch stopper layer is further formed between the semiconductor layer and the ohmic contact layer. The manufacturing method of a liquid crystal display device according to claim 1, wherein the protective film is formed so that at least one layer of an inorganic insulating film and an organic insulating film are laminated. The method of manufacturing a liquid crystal display device according to any one of claims 1 to 8, wherein the organic insulating film is a BCB. The method of claim 1, wherein the organic insulating layer comprises a photosensitive organic material. 1. A liquid crystal display comprising a gate electrode, a semiconductor layer, an ohmic contact layer, a source / drain electrode branching from a gate bus line, a protective film, and a pixel electrode; Wherein the protective film is at least one selected from the group consisting of F-doped polyimide, Teflon, Cytop, fluorinated polyaryl ether, F-parylene, PFCB and SI- And is formed so as to be laminated on the insulating film. The liquid crystal display device according to claim 11, wherein the inorganic insulating film is formed to have at least one layer with a thickness of about 500 to 2000 ANGSTROM, and the organic insulating film has a thickness of 1 mu m or more. The liquid crystal display of claim 11, wherein the pixel electrodes are formed on the protective film so as to selectively overlap the data bus lines. The liquid crystal display of claim 11, wherein the pixel electrode is formed on the passivation layer so as to selectively overlap the gate bus line adjacent to the gate bus line and the data bus line. The liquid crystal display device according to claim 11, wherein the pixel electrode is formed before forming the semiconductor layer. 12. The liquid crystal display device according to claim 11, wherein the pixel electrode is formed after the semiconductor layer is formed. 12. The method of claim 11, further comprising: And an etch stopper layer is further formed on the semiconductor layer and the ohmic contact layer. The liquid crystal display device according to claim 11, wherein the protective film is formed so that at least one or more inorganic insulating films and organic insulating films are laminated. The liquid crystal display device according to any one of claims 11 to 18, wherein the organic insulating film is BCB. The liquid crystal display of claim 11, wherein the organic insulating layer comprises a photosensitive organic material.