KR100202232B1 - Structure and fabrication method of liquid crystal display device - Google Patents

Abstract

The present invention is a transparent substrate, a gate electrode, a gate insulating layer, a semiconductor layer, a gas flow rate SiH the gate insulating film in the manufacturing method of the liquid crystal display device comprising a source electrode and a drain electrode _4: O ₂ is 1: 10 20, substrate temperature is 350 Or less, and in conditions using N ₂ as a diluent gas applying the manufacturing method of forming by deposition the transparent substrate.

This manufacturing method is 400 after forming the gate electrode Since the insulating film is not deposited at the high temperature, there is no fear of heel lock due to stress of the metal such as the gate electrode. Can be improved.

Description

Manufacturing Method of Liquid Crystal Display and Structure of Liquid Crystal Display

1 is a cross-sectional view of a liquid crystal display device for explaining the conventional technology.

2 is a plan view of a liquid crystal display device for explaining the conventional technology.

3 is the second - Section of the line.

4 is a cross-sectional view for explaining an embodiment of a liquid crystal display device according to the present invention.

* Explanation of symbols for main parts of the drawings

11,12: transparent substrate 15: pixel electrode

16 TFT 17 Common electrode

13 spacer 14 liquid crystal

18: gate bus line 19: source bus line

35: etch stopper layer 18a: gate electrode

19a: source electrode 19b: drain electrode

23: first insulating film 22: semiconductor layer

25: ohmic contact layer 26: protective film

21: second insulating film 31: contact hole

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device in which a thin film transistor (hereinafter referred to as TFT) is incorporated, and more particularly, to a structure and a manufacturing method of a TFT.

In this type of liquid crystal display, for example, as shown in FIGS. 1 and 2, the transparent substrates 11 and 12 are separated by a spacer 13 for maintaining a cell gap. It is provided to face each other at predetermined intervals which can be injected.

A plurality of pixel electrodes 15 are formed on the inner surface of one transparent substrate 11.

Each pixel electrode 15 is formed with a TFT 16 serving as a switching element.

The drain electrode of the TFT becomes a portion connected to the pixel electrode.

A transparent common electrode 17 is formed on the inner surface of the other transparent substrate 12 facing the plurality of pixel electrodes 15.

The pixel electrodes 15 are rectangular, for example, arranged in a lattice shape on the transparent substrate 11 in close proximity to each other in the longitudinal and transverse directions.

Gate bus lines 18 are formed in close proximity to the lateral directions of the pixel electrodes 15.

In addition, a source bus line 19 is formed to be close to the longitudinal direction of the pixel electrode 15.

The TFT 16 is provided near the intersection of the gate bus line 18 and the source bus line 19.

The gate electrodes of the TFTs provided at the intersection points are branched at the gate bus lines 18, and the source electrodes are branched at the source bus lines 19. The gate electrodes of the TFTs shown in FIG.

When each of the gate bus line 18 and the source bus line 19 is selected and a voltage is applied, only the TFT 16 to which the voltage is applied is turned ON, and the pixel electrode connected to the drain electrode of the turned on TFT Charges are accumulated in the 15 so that voltage is applied only to the liquid crystal 14 portion between the pixel electrode 15 and the common electrode 17.

The liquid crystal to which the voltage is applied changes the angle of the liquid crystal molecules, and transmits or blocks light depending on the angle of the liquid crystal molecules.

By using the same principle as described above, transmission and blocking of light may be selectively controlled for each pixel electrode 15.

The conventional transparent substrate 11 including the TFT 16 is, for example, shown in FIGS. - It is comprised as shown in FIG. 3 which showed the cross section.

The gate bus line 18 formed laterally on the transparent substrate 11 and the gate electrode 18a branching in the longitudinal direction from the gate bus line 18 are formed of a high melting point metal film such as Mo or Cr.

On the transparent substrate 11 on which the gate electrode 18a is formed, a first insulating film 23 made of an inorganic film such as SiNx, SiOx or the like is formed by a plasma enhanced chemical vapor deposition (hereinafter referred to as PECVD) method.

The first insulating film 23 is commonly referred to as a gate insulating film.

A second insulating film 21 made of SiNx or the like and a semiconductor layer 22 made of amorphous silicon (hereinafter referred to as a-Si) or the like are formed on the first insulating film 23 of the gate electrode 18a.

The second insulating film 21 serves to obtain a good interface with the semiconductor layer and to improve the threshold voltage of the TFT.

An etch stopper layer 35 made of SiNx or the like and an ohmic contact layer 25 are formed on the semiconductor layer 22 such as a-Si.

Subsequently, source bus lines 19 formed in the longitudinal direction and source electrodes 19a branching laterally from the source bus lines 19 are formed.

In addition, the drain electrode 19b is formed at a predetermined distance from the source electrode 19a.

The source electrode 19a and the drain electrode 19b are formed to contact the ohmic contact layer 25.

A protective film 26 made of an inorganic film such as SiNx is formed to cover the source drain electrode and the like, and an ITO (Indium Tin Oxide) which is a transparent conductive film contacting the drain electrode 19b through the contact hole 31 of the drain electrode part. A film is formed on the protective film 26 to form the pixel electrode 15.

However, in the conventional liquid crystal display device, an important factor that governs the characteristics of the TFT is the first insulating film 23 which is a gate insulating film.

As the first insulating film of the TFT, a SiOx film deposited by PECVD is frequently used. The problem of the PECVD method is that particles generated by the gas phase polymerization reaction tend to be generated because a large amount of highly reactive species are generated by increasing the decomposition reaction of SiH _{4 in} the plasma space.

Such particles cause point bonding and predecession of the image because they cause the pin-capacitance at the intersection of the sub-capacitance electrode portion and the gate bus line and the source bus line to assist the pixel potential in manufacturing a TFT element.

Accordingly, as a solution to the above problems, defects such as pinholes and particles are eliminated by depositing SiOx films using some Atmosphreric Pressure Chemical Vapor Deposition (hereinafter, referred to as atmospheric pressure CVD).

However, the problem of the atmospheric CVD method is 400 Because of the high temperature deposition, when a low melting point metal (aluminum series) is used as a gate electrode or a gate bus line instead of a high melting point metal such as Mo or Cr, hillock occurs due to thermal stress, resulting in a gate bus line and a source. The short circuit between the bus lines or the storage capacitor electrode portion assisting the pixel potential causes a decrease in productivity.

In order to solve the problems of Hillock and the like, the present invention provides a gas flow rate ratio of SiH ₄ : O ₂ 1: 10. 20 and substrate temperature is 350 A first insulating film made of SiOx is deposited on the transparent substrate 11 under the following conditions.

Hereinafter, an embodiment of a method of manufacturing a liquid crystal display device according to the present invention will be described in detail with reference to the process cross section of FIG.

EXAMPLE

A metal film, for example, an aluminum film is deposited on the transparent substrate 11 and then patterned to form a gate bus line 18 and a gate electrode 18a branched from the gate bus line (FIG. 4A).

The gate bus line 18 is not shown in the cross sectional view.

An anode oxide film may be formed to increase insulation and prevent hillock after FIG. 4A, but the description thereof will be omitted.

After the above step, a SiOx film serving as a first insulating film as a gate insulating film is deposited on the substrate (FIG. 4B).

Deposition of the first insulating film 23 is performed by using SiH ₄ and O ₂ as source gas and N ₂ as dilution gas in atmospheric pressure CVD.

Substrate temperature is 350 The gas flow rate is adjusted to be a ratio below.

In this embodiment, for example, the gas flow rate ratio SiH ₄ : O ₂ is 1: 10. It was set to 20.

Subsequently, the SiNx layer serving as the second insulating film, the a-Si layer serving as the semiconductor layer, and the SiNx layer serving as the etch stopper layer are successively deposited by PECVD and then patterned to form the second insulating film 21 and the semiconductor layer 22. An etch stopper layer 35 is formed (FIG. 4C).

The second insulating layer 21 and the etch stopper layer 35 may be omitted in some cases.

However, when the second insulating film is omitted and the SiO ₂ layer and the a-Si layer are directly applied, the threshold voltage of the TFT is high and the value of the field effect mobility is small, so that it is difficult to match the peripheral driving circuit. 2 An insulating film is formed.

In addition, the etch stopper layer 35 may be formed by continuously depositing SiOx or SiOx and SiNx using a low temperature atmospheric pressure CVD method.

Subsequently, the semiconductor layer is doped with ions so as to be an n ⁺ a-Si layer and deposited, and then patterned to form an ohmic contact layer 25 (FIG. 4D).

Subsequently, a metal film, for example, an aluminum or chromium film is deposited, and then patterned to form a source bus line 19 functioning as a signal line, a source electrode 19a and a drain electrode 19b branched from the source bus line 19. (Fig. 4e).

The source bus line 19 is not shown in the process sectional view.

Subsequently, a protective film 26 made of an inorganic insulating film or an organic insulating film is deposited on the substrate, and a contact hole 31 connecting the drain electrode 19a and the pixel electrode 15 is formed (FIG. 4f).

Subsequently, an ITO film is deposited on the protective film by sputtering, and the ITO film is patterned to form a pixel electrode 15 (FIG. 4G).

In the manufacturing method according to the above embodiment, the substrate temperature is 350 in an atmospheric pressure CVD apparatus. Gas flow ratio is less than SiH ₄ : O ₂ is 1: 10 The formation of the first insulating film 23 on the gate electrode made of the low melting point metal of the TFT under the condition of 20 is the most characteristic point distinguished from the conventional manufacturing method.

The effect on the above is that the first insulating film is 400 as in the conventional manufacturing method. 350 without deposition at high temperatures Since the deposition is performed at the following low temperature, even if the low melting point metal is used as the gate electrode or the like, there is no fear of the hillock due to the stress of the metal film.

Therefore, in general, the conductivity can be improved because a low melting point material having a lower resistance than a high melting point material having a high resistance can be used.

In addition, 350 Since the protective film 26 can be deposited at the following low temperature, it is possible to prevent destruction of TFTs and malfunctions due to high temperatures.

Claims (7)

A method of manufacturing a liquid crystal display device comprising a substrate, a gate electrode, an insulating film, a semiconductor layer, a source electrode and a drain electrode; The insulating film has a gas flow rate ratio of SiH ₄ : O ₂ equal to 1: 10. 20, the temperature of the substrate is 350 A method for manufacturing a liquid crystal display device, which is deposited under the following conditions. The method of claim 1; The insulating film is a method of manufacturing a liquid crystal display device, characterized in that formed by atmospheric pressure CVD. The method of claim 1; And the insulating film includes a first insulating film serving as a gate insulating film. The method of claim 3; And the first insulating layer is SiOx. A substrate; A gate electrode formed on the substrate; Gas flow ratio SiH ₄ : O ₂ is 1: 10 by atmospheric pressure CVD on the substrate on which the gate electrode is formed. 20, and the temperature of the substrate is 350 A first insulating film formed under the following conditions; A semiconductor layer formed in an island shape on the first insulating film of the gate electrode part; An ohmic contact layer formed separately on both sides of the semiconductor layer; Source and drain electrodes formed on both ohmic contact layers; A protective film formed to cover the substrate on which the source drain electrode is formed; And a pixel electrode in contact with the drain electrode through the passivation layer and formed on the passivation layer. The method of claim 5; And the first insulating layer is SiOx. The method of claim 6; And a second insulating film made of SiNx is formed between the first insulating film and the semiconductor layer formed in the island shape.