KR19990012715A - Structure of Substrate of LCD and Manufacturing Method Thereof - Google Patents

Abstract

The present invention relates to a substrate of a liquid crystal display device. When a conductive film is formed to be in contact with the metal film by etching a portion of the protective film applied on the metal film, a contact resistance is not formed at the boundary between the metal film and the conductive film. There is a purpose.

In the substrate of the liquid crystal display of the present invention, a process of forming a metal film 360 such as Mo, Ta, W, etc. in a predetermined pattern, and forming a protective film 155 made of an organic or inorganic film including an Si group to cover the patterned metal film Etching a portion of the passivation layer 155 so that a portion of the surface of the metal layer 360 is exposed in a chamber containing SF ₆ or CF ₄ gas, and simultaneously etching a thickness of the exposed surface of the metal layer 100 Å or more. It is formed through.

Accordingly, the surface of the etched metal film is removed from the diffusion insulating layer formed by the diffusion of organic or inorganic materials, and the insulating film such as an oxide film is not formed when etched using SF ₆ / O ₂ or CF ₄ / O ₂ gas. Therefore, no contact resistance is formed between the etched metal film and the conductive film.

Description

Structure of Substrate of LCD and Manufacturing Method Thereof

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device using a thin film transistor (hereinafter referred to as TFT) as a switching element, and in particular, to a contact resistance of a metal film generated during patterning of a metal film and an insulating film.

A substrate constituting a conventional liquid crystal display device has a pixel electrode 80 formed in an area where two adjacent gate bus lines 60 and two adjacent data bus lines 70 intersect each other, as shown in FIG. The TFT 37 in electrical contact is formed near the intersection of the gate bus line 60 and the data bus line 70.

The TFT 37 includes a gate electrode 61 branching from the gate bus line 60, a source electrode 71 branching from the data bus line 70, a drain electrode 72 disposed to face the source electrode, a semiconductor layer 90, and the like.

The portion 33 where the pixel electrode 80 and the gate bus line 60 overlap with each other serves as a storage capacitor electrode.

The manufacturing method of the board | substrate of the conventional liquid crystal display device comprised as mentioned above is demonstrated by FIG. 2 (sectional drawing cut | disconnected along the II-II line of FIG. 1).

First, a Cr metal film is deposited on a transparent glass substrate 10 by a sputtering method, and a photoresist is coated on the Cr metal film by spin coating. After exposing the photoresist using a mask, the photoresist is developed to a predetermined pattern, and the Cr metal film is etched with an etchant such as CAN (ceric ammonium nitrate) according to the developed pattern, and then, at the gate bus line and the gate bus line. After forming the branching gate electrode 61, the photoresist remaining on the metal film is removed with an organic solution of NMP (N-Methyl-Pyrrolidone), a mixture of alcohol and amine.

Subsequently, an inorganic insulating film made of SiN _X , SiO _X or the like serving as the gate insulating film 50, an a-Si layer serving as the semiconductor layer 90, and an a-Si layer doped with n ⁺ ions serving as the ohmic contact layer 100 are then subjected to the surfer method. The film was continuously deposited on the a-Si layer doped with n ⁺ ions and spin-coated a photoresist. After exposing the photoresist using a mask, the photoresist is developed in a predetermined pattern, and the a-Si layer and the a-Si layer doped with n ⁺ ions are simultaneously dry-etched or wet-etched according to the developed pattern. The photoresist remaining on the a-Si layer doped with n ⁺ ions is removed with an organic solution of NMP (N-Methyl-Pyrrolidone), a mixture of alcohol and amine.

Due to the etching, the semiconductor layer 90 and the ohmic contact layer 100 are formed in an island shape on the gate insulating layer of the gate electrode 61.

Subsequently, a Cr metal film is deposited on the entire surface of the substrate on which the ohmic contact layer 100 is formed by sputtering, and a photoresist is coated on the Cr metal film by spin coating. After exposing the photoresist using a mask, the photoresist is developed to a predetermined pattern, and the Cr metal film is etched with an etchant such as CAN (ceric ammonium nitrate) according to the developed pattern.

A data bus line 70 is formed on the gate insulating layer 50 by the etching, and a source electrode 71 branching from the data bus line 70 and a drain electrode 72 facing the source electrode 71 are formed on the ohmic contact layer 100. A portion of the drain electrode may be formed to extend on the gate insulating layer 50.

Using the source electrode 71 and the drain electrode 72 as a mask, the exposed ohmic contact layer is removed by dry etching, and the photoresist is formed on the data bus line, the source electrode and the drain electrode with N-Methyl-Pyrrolidone (NMP). Remove with an organic solution of a mixture of alcohol and amine.

Subsequently, a protective film 55 made of SiN _X , SiO _X or benzocyclobutene (BCB) containing Si groups is coated on the entire surface of the substrate on which the source and drain electrodes are formed, and the photoresist is spin coated on the protective film. Apply with After exposing the photoresist using a mask and developing in a predetermined pattern, the exposed protective film is etched in a dry etching chamber using SF ₆ / O ₂ or CF ₄ / O ₂ gas according to the developed pattern. do.

Due to the dry etching, a contact hole 30 through which a portion of the drain electrode 72 is exposed is formed.

The dry etching mechanism of the protective film will be described in more detail as follows.

The exposed protective film starts to be etched because the Si group of the exposed protective film reacts with the F group of the etching gas and turns into a volatile substance of SiF ₄ . Simultaneously with the etching, the photoresist covered on the protective film is removed by ashing with O ₂ gas.

After forming a contact hole on the protective film and removing the photoresist as described above, an ITO (Indium Tin Oxide) film is deposited on the entire surface of the protective film 55 by sputtering, and the photoresist is coated on the ITO film by spin coating. After exposing the photoresist using a mask, the photoresist is developed to a predetermined pattern, and the ITO film is etched with an etchant such as HCl according to the developed pattern to form a pixel electrode 80.

Through the above process, a switching element (TFT) 37 including a semiconductor layer 90, a source electrode 71, a drain electrode 72, a gate electrode 61, and the like is formed on one substrate of the liquid crystal display device, and the drain electrode 72 of the switching element 37 is formed. Is made to be in contact with the pixel electrode 80 via the protective film 55.

On the other hand, the cross section of the gate pad portion and the data pad portion located at the end of each gate bus line and data bus line and in contact with the tape automated bonding (TAB) of the IC has a structure as shown in FIG.

In FIG. 3, 92 is formed of a Cr metal film such as a metal film forming a gate bus line and a data bus line, and is connected to the gate bus line or the data bus line.

Further, 55 is a protective film made of SiN _X, SiO _X BCB or the like containing an Si, 93 is an ITO film formed in order to facilitate the contact with a terminal of the IC TAB.

In particular, the ITO film 93 in contact with the pass portion contacts the Cr metal film 92 after etching a part of the protective film 55 using SF ₆ / O ₂ or CF ₄ / O ₂ gas.

However, in the substrate of the conventional liquid crystal display device configured as shown in FIGS. 2 and 3, the protective film 55 is SF ₆ / O ₂ or CF so that a part of the drain electrode 72 made of the Cr metal film or the Cr metal film 92 of the pad part is exposed. _In the process of etching with ₄ / O ₂ gas, a thin insulating film 75 is formed on the surface of the Cr metal film exposed to the etching gas.

Since the thin insulating film 75 increases the contact resistance of the conductive film that is in contact with the Cr metal film, that is, the ITO film, the display quality of the liquid crystal display device may be degraded, such as raining on the screen. Cause.

The reason why the insulating film 75 is formed on the surface of the Cr metal film can be classified as follows.

One reason is that when the protective film made of an organic insulating material or the like is coated on the Cr metal film, the organic insulating material diffuses to the surface of the Cr metal film by a predetermined thickness to form an insulating film;

Another reason is that when the surface of the Cr metal film is exposed to the etchant of the protective film, a thin insulating film is formed on the surface of the Cr metal film. The thin insulating film formed when the surface of the Cr metal film is exposed to an etchant such as a protective film is presumably because an oxide film is formed by the reaction between the etchant and the Cr metal, but a specific mechanism is not known. In fact, when the contact resistance of the Cr metal film surface is measured according to the time when the surface of the Cr metal film is exposed to the etchant, it can be seen that the contact resistance increases in the form of a graph of FIG. 4. In FIG. 4, Rc is a contact resistance, and T is a time when the surface of the Cr metal film is exposed to the etchant.

According to the present invention, when the protective film is formed on the metal film as described above, the protective film is etched to expose the metal film, and the conductive film such as ITO is brought into contact with the exposed metal film. The purpose is to prevent a thin insulating film from being formed at the boundary of the film.

The present invention forms a metal film in contact with the lower layer of the protective film to be etched in the etchant of the protective film to achieve the above object.

That is, as an example, when an inorganic or organic film such as SiN _X , SiO _X or BCB containing a Si group is used as an insulating protective film, etching is performed in SF ₆ / O ₂ or CF ₄ / O ₂ gas used as an etchant of the insulating protective film. A metal film such as Mo, W, Ta, or the like is formed as a drain electrode, a gate pad or a data pad of the switching element.

Referring to FIG. 5, the insulating protective film 155 including the Si group is covered on the metal film lamps such as Mo, W, and Ta, and a part of the insulating protective film 155 is formed of SF ₆ / O ₂ or CF ₄ / O ₂ gas. After etching to form the contact hole 300, a conductive film 193 such as ITO is formed on the insulating protective film 155 to be in contact with the metal film lamp. When the surface of the metal film lamp is exposed when forming the contact hole 300, the F group and the metal film react with SF ₆ / O ₂ or CF ₄ / O ₂ gas (MoF ₆ using Mo metal, WF ₃ using W metal). , in the case of using a Ta metal changed to volatile substances TaF ₄₎ to the metal film surface is etched.

The etching thickness A of the metal film should be 100 kPa or more so that all of the insulating film diffused on the surface of the metal film may be removed in the process of applying the insulating protective film 155 on the metal film lamp.

As described above, the surface of the metal film is etched 100 Å or more by an etchant of the protective film, and the contact layer is not formed between the metal film and the conductive film by contacting the ITO conductive film 193 so that an impurity layer is not formed. . Particularly, when patterning the metal film 360 by laminating with another metal film is preferable in terms of uniformity and precision of the pattern width, forming another metal film 260 as shown in FIG. 6 does not depart from the object of the present invention. Do not.

1 is a plan view of a substrate of a conventional liquid crystal display device;

FIG. 2 is a cross-sectional view taken along the line II-II of FIG. 1;

3 is a cross-sectional view showing a conventional pad structure,

4 is a graph showing the relationship between the contact time and the time when the Cr metal film is exposed to an etchant such as SF ₆ / O ₂ or CF ₄ / O ₂ ;

5 and 6 are cross-sectional views for explaining a schematic structure of the present invention.

7a to 7j are sectional views of the manufacturing process for explaining the embodiment of the present invention,

8 is a graph showing the relationship between the etching thickness and the contact resistance of a metal film of Mo, W, Ta, etc. of the present invention.

* Description of the symbols for the main parts of the drawings *

10, 110 Transparent glass substrate 33 Auxiliary capacitor electrode part

37 TFT50, 150 gate insulating film

55, 155 Shield 60 Gate Bus Line

61, 161a gate electrode 70, 170a data bus line

71, 170b source electrode 72, 170c drain electrode

75 insulating film 80, 180 pixel electrode

90, 190 semiconductor layers 193, 280 ITO film

100, 200 ohmic contact layer 400 photoresist

The substrate of the liquid crystal display of the present invention includes a metal film having a first region and a second region, a protective film covering the metal film portion of the first region, and a conductive film in contact with the surface of the metal film of the second region. In particular, the thickness of the surface of the metal film of the second region is 100 kPa or more.

The metal film may be formed of any one of Mo, Ta, and W, and the protective film may be formed by stacking any one or more materials selected from inorganic or organic materials, such as SiN _X , SiO _X , and BCB, including Si groups. A conductive film in contact with the metal film of the second region is formed on the protective film.

In addition, the metal film may include at least a source and drain electrode, a gate pad part, and a data pad part of a switching device, and another metal film may be stacked below the metal film.

A method of manufacturing a substrate of a liquid crystal display device having the above structure includes forming a metal film such as Mo, Ta, and W in a predetermined pattern, and forming a protective film with an organic or inorganic film including an Si group to cover the patterned metal film. And removing a part of the protective film so that a part of the surface of the metal film is exposed, and removing a thickness of the exposed metal film by 100 Å or more, and in particular, the protective film so that a part of the surface of the metal film is exposed. The process of removing a portion of the film and removing the thickness of the exposed metal film by 100 Å or more may be performed continuously by reaction with the gas in a chamber containing SF ₆ or CF ₄ gas.

Hereinafter, the manufacturing process and operation of the substrate of the liquid crystal display of the present invention will be described in detail.

EXAMPLE

A metal film 161 selected from Mo, W, and Ta was deposited on the transparent glass substrate 110 by a sputtering method, a photoresist 400 was coated on the metal film 161 by spin coating, and the photoresist 400 was exposed using a mask. After that, the pattern is developed to have a predetermined pattern (Fig. 7A).

Subsequently, a substrate in the state of FIG. 7A is placed in the chamber, and SF ₆ / O ₂ or CF ₄ / O ₂ gas is injected into the chamber to etch the metal film 161 according to the developed pattern, and the photo remaining on the metal film. The resist is removed to form a gate bus line (not shown) and a gate electrode 161a branching from the gate bus line (FIG. 7B).

The etching of the metal film 161 is a reaction between the F group and the metal film of the SF ₆ / O ₂ or CF ₄ / O ₂ gas (MoF _{6 for} Mo metal, WF _{3 for} W metal, TaF _{4 for} Ta metal) To be done). The photoresist can be removed by ashing simultaneously with the etching of the metal film by O ₂ contained in the etching gas, but since the etched impurities can adhere to the metal film surface to form an insulating layer, NMP (N -Methyl-Pyrrolidone) is preferably removed with an organic solution of a mixture of alcohol and amine.

Subsequently, an inorganic insulating film made of SiN _X , SiO _X or the like serving as the gate insulating film 150, an a-Si layer serving as the semiconductor layer 190, and an a-Si layer doped with n ⁺ ions serving as the ohmic contact layer 200 were sputtered. After the deposition, the photoresist 400 was spin coated on the n ⁺ ion-doped a-Si layer, and the photoresist 400 was exposed using a mask and developed in a predetermined pattern (Fig. 7C). .

Subsequently, the a-Si layer and the a-Si layer doped with n ⁺ ions are dry-etched or wet-etched at the same time according to the developed pattern, and a mixture of NMP (N-Methyl-Pyrrolidone), alcohol, and amine is used. and removing the n ⁺ ions remain on the doped a-Si layer 400 on the photoresist by organic solvents. Due to the etching, the semiconductor layer 190 and the ohmic contact layer 200 are formed in an island shape on the gate insulating layer 150 of the gate electrode 161a (FIG. 7D).

Subsequently, a metal film 170 selected from Mo, W, and Ta is deposited on the entire surface of the substrate on which the ohmic contact layer 200 is formed by sputtering, a photoresist 400 is coated on the metal film 170 by spin coating, and a mask is used. Then, the photoresist 400 is exposed and developed to have a predetermined pattern (FIG. 7E).

Subsequently, a substrate in the state of FIG. 7E is placed in the chamber, and SF ₆ / O ₂ or CF ₄ / O ₂ gas is injected into the chamber to etch the metal film 170 according to the developed pattern, and the exposure due to the etching of the metal film. The ohmic contact layer 200 is etched and separated on both sides, and the photoresist remaining on the metal film is removed to form a data bus line 170a and a source electrode 170b and a drain electrode 170c branching from the data bus line (FIG. 7F). .

The etching process for forming the structure of FIG. 7F is the same as the etching process for forming the structure of FIG. 7B. The structure of FIG. 7F is formed on the substrate of the liquid crystal display device so that the gate electrode 161a, the ohmic contact layer 200, the semiconductor layer 190, A switching element composed of the source electrode 170b, the drain electrode 170c, and the like is completed.

Subsequently, a protective film 155 made of SiN _X , SiO _X or BCB containing Si groups is applied to the entire surface of the substrate on which the source and drain electrodes are formed, and the photoresist 400 is coated on the protective film by spin coating, and a mask is applied. The photoresist is exposed to light and then developed in a predetermined pattern (Fig. 7G).

In the present embodiment, the protective film has a structure formed of inorganic films such as SiN _X and SiO _X. However, when the protective film is formed of an organic film such as BCB, the surface of the protective film will have a flat structure.

Subsequently, according to the developed pattern, the exposed protective layer is etched in a chamber into which SF ₆ / O ₂ or CF ₄ / O ₂ gas is injected, thereby forming a contact hole 300 exposing a part of the drain electrode 170c. The surface C of the drain electrode 170c exposed by the formation of the contact hole 300 is etched by the etching gas at least 100 kPa. In more detail, the F layer of the SF ₆ / O ₂ or CF ₄ / O ₂ gas reacts with the Si group of the protective layer to change into a volatile substance of SiF ₄ , thereby exposing the exposed protective layer and simultaneously removing the F of the etching gas. The surface of the exposed metal film is etched since the group reacts with the exposed metal film to become a volatile material. That is, since the surface of the metal film is etched by the volatile material of the MoF ₆ when the drain electrode 170c is Mo metal, the WF ₃ when the W metal, and the TaF ₄ when the Ta metal is etched, impurities such as an insulating film are not formed. Maintain a clean surface. In addition, the photoresist is removed by etching with O ₂ gas included in the etching gas in the process of etching the protective film (FIG. 7H).

The removal of the exposed metal film by etching at least 100 GPa is performed by injecting a protective film onto the metal film, in which atoms of the protective film diffuse into the surface of the metal film to a depth of about 100 GPa, and the diffusion layer forms an insulating film. To eliminate it.

Subsequently, a conductive film 280 made of an indium tin oxide (ITO) film is deposited on the entire surface of the protective film 155 by sputtering, a photoresist 400 is coated on the conductive film by spin coating, and the photoresist is applied using a mask. After exposure, the pattern is developed to have a predetermined pattern (Fig. 7I).

Subsequently, the conductive layer 280 is etched with an etchant such as HCl to form a pixel electrode 180 according to the developed pattern, and the photoresist remaining on the pixel electrode is a mixture of NMP (N-Methyl-Pyrrolidone), alcohol, and amine. Remove with an organic solution (Fig. 7j).

By constructing the substrate of the liquid crystal display device as described above, the pixel electrode 180 and the drain electrode 170c are in contact with each other through the contact hole 300 formed in the passivation layer, that is, the pixel electrode is in contact with the surface C portion of the drain electrode etched by 100 μs or more. Almost no contact resistance is formed at the boundary portion. The contact resistance Rc represents a minimum value when the depth d at which the surface of the metal film is etched is 100 kPa or more, as shown in the graph of FIG. 8.

In the embodiment of the present invention, the metal film is composed of a single layer. However, when patterning the metal film by laminating it with another metal film, it is preferable in pattern uniformity, precision, etc., as shown in FIG. Another metal film 260 can be formed by laminating a metal film lamp made of a lamp or the like.

On the other hand, at each end of the gate bus line and each end of the data bus line is formed a pad portion for contacting the Tape Automated Bonding (TAB) of the IC (not shown), it is apparent that the pad portion is also applied to the present invention. .

According to an embodiment of the present invention, the surface of the Cr metal film is contacted by the etching gas in the process of etching the protective film with SF ₆ / O ₂ or CF ₄ / O ₂ gas so that a part of the surface of the Cr metal film covered with the protective film including the Si group is exposed. This is to solve the conventional problem that a thin insulating film (presumed to be an oxide film) is formed on the substrate.

In the present invention for solving the above problems, a pattern is formed of a metal film selected from Mo, W, and Ta, and a protective film including a Si group is formed to cover the pattern of the metal film.

A portion of the protective film is removed to contact the gate pad portion, the data pad portion, and the drain electrode portion of the switching element, such as ITO, and at the same time, a metal film made of Mo, W, Ta, etc. exposed by the removal of the protective film. The surface is etched more than 100Å. The protective film is removed and the surface of the metal film is etched by an etching method using SF ₆ / O ₂ or CF ₄ / O ₂ gas.

As described above, the surface of the metal film is etched at 100 kPa or more, so that in the process of applying the protective film on the metal film, the diffusion insulating layer formed by diffusion of the constituent atoms of the protective film on the surface of the metal film is removed, and the metal film such as Mo, W, Ta, etc. When etched using F ₆ / O ₂ or CF ₄ / O ₂ gas, an insulating film such as an oxide film is not formed, so that no contact resistance is formed between the conductive films in contact with the metal film.

Therefore, when the liquid crystal display device is configured by using the substrate of the liquid crystal display device of the present invention, there is an effect that the display quality is stabilized without a dropping phenomenon or the like on the screen.

Claims (19)

A metal film having a first region and a second region, A protective film covering the metal film portion of the first region; In the substrate of the liquid crystal display device comprising a conductive film in contact with the surface of the metal film of the second region, The substrate of the liquid crystal display device, wherein the surface of the metal film of the second region is removed by a predetermined thickness or more. The method of claim 1, The metal film is any one of Mo, Ta, W, the protective film is a substrate of a liquid crystal display device, characterized in that made of a material containing a Si group. The method of claim 1, The surface thickness of the metal film of the said 2nd area | region is removed by 100 micrometers or more, The board | substrate of the liquid crystal display device characterized by the above-mentioned. The method according to any one of claims 1 to 3, And the metal film comprises at least one terminal of a switching element. The method according to any one of claims 1 to 3, And the metal film comprises at least a gate pad portion or a data pad portion. The method of claim 2, The protective film is a substrate of a liquid crystal display device, characterized in that by stacking any one or more materials selected from SiN _X , SiO _X , Benzocyclobutene. The method according to any one of claims 1 to 3, A substrate of a liquid crystal display device, wherein another metal film is stacked below the metal film. The method according to any one of claims 1 to 3, A conductive film in contact with the metal film of the second region is formed on the passivation film. The method of claim 8, The conductive film is a substrate of the liquid crystal display device, characterized in that the ITO. Forming a metal film in a predetermined pattern, Forming a protective film covering the patterned metal film, And removing a portion of the protective film so that a portion of the surface of the metal film is exposed, and removing at least a thickness of the exposed surface of the metal film. The method of claim 10, The metal film is any one of Mo, W, Ta, and the protective film is made of a material containing a Si group. The method of claim 10, And a surface thickness of the exposed metal film is removed to be 100 占 퐉 or more. The method of claim 11, The protective film is a method for manufacturing a substrate of a liquid crystal display device, characterized in that by laminating any one or more materials selected from SiN _X , SiO _X , Benzocyclobutene. The method of claim 11, Removing a portion of the protective film so that a portion of the surface of the metal film is exposed, and removing the surface of the exposed metal film by a predetermined thickness or more, the reaction with the gas in a chamber containing SF ₆ or CF ₄ gas A method for manufacturing a substrate of a liquid crystal display device, characterized in that the process is carried out continuously. The method according to any one of claims 10 to 14, And said metal film comprises at least one terminal of a switching element. The method according to any one of claims 10 to 14, And the metal film comprises at least a gate pad portion or a data pad portion. The method according to any one of claims 10 to 14, And forming another metal film on the lower layer of the metal film. The method according to any one of claims 10 to 14, And a conductive film in contact with the metal film is formed on the passivation film. The method of claim 18, The conductive film is ITO, characterized in that the substrate manufacturing method of the liquid crystal display device.