KR100660810B1 - method for fabric ating thin film transistor and array substrate for liquid crystal display device - Google Patents

Abstract

The present invention relates to a method for manufacturing an array substrate for a liquid crystal display device. When the gate electrode of a thin film transistor, which is a switching element of the array substrate, is composed of a double metal layer, the double metal layer is an alkaline mixed solution (ozone water + TMAH (alkali solution). Since the double gate electrode having the tapered shape can be formed using the etching solution of)), the wet etching method and the dry etching method are used in order to eliminate the overhang on the etched metal layer in the etching process of two electrodes stacked with different materials. In the etching method of the dry etching method does not have to use, there is a low cost effect in the process.

Description

Manufacturing method of thin film transistor and array substrate for liquid crystal display device {method for fabric ating thin film transistor and array substrate for liquid crystal display device}             

1 is a plan view showing some pixels of a general array substrate for a liquid crystal display device;

2A to 2C are cross-sectional views of a conventional process taken along II-II of FIG. 1,

3A to 3D are cross-sectional views of the process according to the present invention taken along the line II-II of FIG.

Figure 4 is a block diagram showing an etching system including a mixing process of the etching solution according to the present invention.

<Brief description of symbols for the main parts of the drawings>

201: ozone manufacturing tank 203: primary TMAH concentration titration tank

205: distilled water recycling device 207: secondary TMAH concentration titration tank

209: etching chamber

The present invention relates to a method for manufacturing a thin film transistor and an array substrate for a liquid crystal display device, and more particularly, to a method for manufacturing a thin film transistor for etching a vertical cross-section of the double metal film to form a stepped shape.

1 is a plan view showing a part of a general array substrate for a liquid crystal display device.

As shown in the drawing, the array substrate includes a thin film transistor T, which is a switching element, and a data wiring 13 and a gate wiring 15 which cross each other around the thin film transistor, and each of the wirings cross each other. The pixel region P is defined. In the pixel region P, a pixel electrode 17 is formed.

The thin film transistor T includes a gate electrode 23, a source electrode 25, and a drain electrode 27, and the data line 13 includes the plurality of thin film transistors T arranged in a matrix form. Is connected to the source electrode 25 while passing in the direction, and the gate wiring 15 is connected to the gate electrode 23 while passing through the plurality of thin film transistors T in one direction.

In addition, a storage capacitor C connected to the pixel electrode 17 in series with the gate wiring 15 is formed.

In the above configuration, the gate electrode and the gate wiring are generally formed of a first metal layer first with aluminum and an aluminum alloy, and then a second metal layer is formed by depositing a metal such as chromium or molybdenum on the first metal layer to form a conductive layer. It is formed of metal.

The reason why the first metal layer of the gate wiring is formed of aluminum is to use a metal having a small resistance such as aluminum in order to prevent a signal delay caused by the wiring resistance of the gate wiring. However, the aluminum-based metal is not easy to match the etching rate during the etching process because of the low corrosion resistance by chemicals, and easily oxidized, resulting in disconnection of the wiring.

Therefore, in order to prevent this, chromium (Cr), molybdenum (Mo), etc., which are highly resistant to chemicals, are formed on the aluminum metal to form a double layer gate electrode.

In the process of etching the aluminum-based metal and the chromium in the form of the gate electrode and the gate wiring, when the two materials are etched with the same etching solution, the aluminum metal has a large etching rate in the etching solution. Among them, it is difficult to control the etching rate, and aluminum metal has more side etching than molybdenum metal due to the large difference in etching rate between molybdenum metal in the upper layer. That is, the gate metal as a whole has an inverse tapered shape, and the upper molybdenum generates an overhang that protrudes laterally than the lower aluminum.

The vertical cross section of the gate pattern having such an overhang structure cannot obtain sufficient coverage with the insulating film deposited on the gate pattern. For this reason, problems such as short-circuit defects and breakdown voltages occur with the metal layer formed in the upper layer in the vertical cross-section.

This problem not only lowers the electrical characteristics of the gate wiring but also lowers the yield of the product.

Therefore, continuous research has been conducted to solve this problem.

Hereinafter, a manufacturing process of an array substrate including a gate electrode having a dual structure will be described with reference to the accompanying drawings.

Such a manufacturing process of the gate electrode will be described with reference to the accompanying process cross section below.

2A to 2C are cross-sectional views taken along the line II-II of FIG. 1.

First, as shown in FIG. 2A, first, an aluminum neodymium (AlNd) layer 10 and a molybdenum (Mo) layer 11, which are aluminum alloys, are sequentially stacked on a substrate, and a photoresist for forming a gate pattern is formed. (12) is applied.

Next, as shown in FIG. 2B, the gate is patterned by simultaneously etching the molybdenum layer 11 as an upper layer and the aluminum neodymium layer 10 as a lower layer with a phosphate etching solution using a gate pattern. At this time, the aluminum neodymium layer 10 and the molybdenum layer 11 is different in the etching rate of the two metal layers due to the potential difference due to galvanic phenomenon.

 That is, the aluminum neodymium layer 10 has a large etching rate in an etching solution, so it is difficult to control the etching rate during the process, and the aluminum neodymium layer 10 has a large difference between the molybdenum layer 11 and the etching rate of the upper layer. The side etching is more than that of the molybdenum layer 11. That is, the gate metal as a whole has an inverse taper shape, and the upper molybdenum 14 generates an overhang 16 which protrudes laterally than the lower aluminum 15.

 Therefore, in order to reduce such an overhang phenomenon, only the upper layer portion is dry-etched again using the resist film 13 as a mask. In this case, the overhang portion of the resist layer 13 and the molybdenum layer 11 below Remove 16) at the same time.

That is, the etching gas used for the dry etching is a method of first ashing the resist film 13 by an appropriate combination of oxygen (O ₂ ) and fluorine-based gas, and then oxidizing and removing the molybdenum layer. To form a gate electrode and a gate wiring in which the overhang does not occur.

However, in the process, wet etching and dry etching are performed to form a double gate electrode having a structure in which both sides are inclined obliquely, so that different etching methods are used, and the dry etching is performed. Compared to wet etching, there is a disadvantage in that a high process cost is generated, such as the use of large equipment.

Accordingly, an object of the present invention is to propose a method capable of patterning the double gate electrode in a simpler process at a lower cost in order to solve the problems as described above.

A thin film transistor manufacturing method for achieving the object of the present invention as described above comprises the steps of sequentially depositing a first metal layer and a second metal layer on a substrate; Applying a resist film on the second metal layer; Patterning the resist film to form a resist pattern; Forming a gate electrode by wet-etching a first metal layer and a second metal layer simultaneously using an alkali mixed solution of ozone water and TMAH solution using the resist pattern as a mask; Forming a gate insulating film on the substrate including the gate electrode; And forming a source electrode and a drain electrode on the active layer on both sides of the gate insulating layer and on the gate insulating layer corresponding to the gate electrode.

Preferably, the ozone water is an alkaline solution in which ozone is dissolved in distilled water.

Preferably, the concentration of ozone water is characterized in that less than 10ppm.

Preferably, the TMAH solution is characterized in that diluted in distilled water.

More preferably, the concentration of the TMAH solution is characterized in that 2.38 mol%.

Preferably, the first metal layer is aluminum (Al) or aluminum neodymium (AsNd).

According to an aspect of the present invention, there is provided a method of manufacturing an array substrate for a liquid crystal display device, comprising: depositing a conductive metal including aluminum on a substrate to form a first metal layer, and subsequently depositing molybdenum to form a second metal layer; Applying a resist film on the second metal layer; Patterning the resist film to form a resist pattern;
Forming a gate electrode and a gate wiring by wet-etching a first metal layer and a second metal layer simultaneously with an alkaline mixed solution of ozone water and TMAH solution using the resist film pattern as a mask; Forming a first insulating layer on the substrate on which the gate wiring and the gate electrode are formed; Forming an active layer on the first insulating layer corresponding to the gate electrode; Forming a source electrode and a drain electrode on the active layer and a data line crossing the gate line to define a pixel area; Forming a second insulating layer on the substrate including the data line; And forming a transparent pixel electrode on the pixel region.

Preferably, the concentration of ozone water is characterized in that less than 10ppm.

Preferably, the ozone water is an alkaline solution in which ozone is dissolved in distilled water.

More preferably, the concentration of ozone water is characterized in that 10ppm or less.

The TMAH solution is characterized in that diluted in distilled water.

Preferably the concentration of the TMAH solution is characterized in that 2.38 mol%.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings.

3A to 3E are cross-sectional views taken along the line II-II of FIG. 1.

As shown in FIG. 3A, a metal such as aluminum neodymium (AlNd), which is an aluminum alloy, is deposited on the glass substrate 111 to form the first metal layer 100. Then, metals having a high melting point such as molybdenum (Mo), tantalum (Ta), tungsten (W), or antimony (Sb) are continuously deposited. In this embodiment, molybdenum is deposited to form the second metal layer 101. do.

After forming the second metal layer, a photoresist 103 is coated on the second metal layer.

Next, as shown in FIG. 3B, after the photoresist is patterned with the first mask on the second metal layer 101, the vertical cross section of the photoresist 103a is heated to form a hemispherical shape. do.

Next, as shown in FIG. 3C, the alkaline metal etching solution (DI (distilled water) + TMAH) is used for the second metal layer 101 and the first metal layer 100 using a hemispherical photoresist whose vertical cross section is a mask. Wet etching is performed simultaneously with (alkali etching solution) + O ₃ (ozone water).

At this time, the alkaline etching solution is formed by mixing a TMAH solution based on distilled water and ozone water.

The TMAH solution is represented by a molecular formula of (CH ₃ ) ₄ NOH and is also used as a developer of a photoresist, or used to etch other materials.

The TMAH solution exhibits particularly strong etching characteristics for aluminum, and can control the concentration of TMAH diluted in distilled water to match the etching ratio for the aluminum.

The ozone water is obtained by mixing the ozone (O ₃ ) with distilled water (DI). The ozone can be easily obtained by a commercial method, and can also be easily obtained by discharging oxygen (O ₂ ) in a laboratory.

The ozone exhibits strong etching characteristics among molybdenum (Mo) metals among various materials. Therefore, the etching rate of the molybdenum can be adjusted by controlling the concentration of ozone mixed in the distilled water.

An etching system using the etching solution used to etch a gate electrode having a double structure of the aluminum neodymium layer 100 and the molybdenum layer 101 will be described with reference to FIG. 4.

Figure 4 is a block diagram showing an etching system (etching system) including the mixing process of the alkaline-based etching solution according to this embodiment.

The ozone water and the diluted TMAH solution are made separately and mixed, which is a means of simultaneously etching a double metal layer formed on the array substrate in an etching chamber.

In detail, ozone (O ₃ ) generated in the ozone manufacturing apparatus 201 is dissolved in distilled water to generate ozone water. At this time, the temperature of the distilled water is adjusted to a temperature of 0 ° C to 30 ° C so as to adjust the concentration of the ozone water to 10 ppm or less.

 On the other hand, the TMAH solution having a predetermined concentration is contained in the first concentration titration tank 203 and diluted using distilled water recycled in the distilled water recycling 205 apparatus.

At this time, the TMAH solution has a concentration value of 2.38 mol%.

The ozone water and the diluted TMAH solution are mixed in the secondary TMAH concentration titration tank 203.

The mixed solution (ozone water + TMAH) is introduced into the etching chamber 209 to etch a material stacked on the array substrate in a predetermined pattern.

When the etching process is completed, it is easy to supply a low-cost etching solution because only the distilled water of the mixed solution can be recycled.

With this etching system, the mechanism by which the mixed solution etches the double metal layer for forming the gate electrode 104 will be described with reference to the process cross section of FIG. 3C.

The mixed solution in which the ozone water and the TMAH solution are mixed is etched away from the metal except for the portion using the photoresist 103a as a mask. First, the molybdenum layer 101a is vertically cross-sectioned by ozone water in the mixed solution. Etched to have.

Next, the aluminum neodymium layer 100a under the molybdenum layer 101a is etched obliquely by the TMAH solution.

Since the alkaline mixed solution has an etching selectivity with respect to the double metal layer forming the gate electrode 104, the etching rate for each layer is possible by controlling the concentration and temperature of the mixed solution. The side of can be configured to be inclined without overhanging.

3D, a first insulating layer 107 is formed by depositing a silicon nitride film (SiN _X ) or a silicon oxide film (SiO ₂ ) on the gate electrode 101 having the dual structure. .

Next, a semiconductor layer and an impurity semiconductor layer are sequentially stacked on the gate insulating layer 107, and an active layer 109 formed in an island shape is formed on the gate electrode.

Next, a conductive metal is deposited and patterned on the entire surface of the substrate 111 on which the active layer 109 is formed, and then data lines defining the pixel region P to cross the gate wiring (see FIG. 1). 1 and 13) and a source electrode 112 protruding upward from the gate electrode 104 in the data line and a drain electrode 113 spaced a predetermined distance from the gate electrode 104.

Next, an inorganic insulating material such as silicon nitride film (SiN _X ) or silicon oxide film (SiO ₂ ), benzocyclobutene (BCB), and the like on the entire surface of the substrate 111 on which the source electrode 112 and the drain electrode 113 are formed. An organic insulating material such as acryl is deposited to form and pattern the protective layer 115, which is the second insulating layer, to form a drain contact hole 117 on the drain electrode 113.

Next, a transparent conductive metal such as indium tin oxide or indium zinc oxide is deposited and patterned on the entire surface of the substrate 111 on which the drain contact hole 117 is formed, and then through the drain contact hole 117. A pixel electrode 119 is formed in contact with the drain electrode 113 and positioned on the pixel region P.

In the above-described process, a thin film transistor array substrate for a liquid crystal display device can be manufactured.

As described above, the present invention is a method of manufacturing a double-gate gate electrode of a thin film transistor array substrate, by using an alkaline mixed solution (ozone water + TMAH) to etch the two-layer metal without an overhang, the conventional wet + dry In the two-step etching process of etching, the dry etching process can be omitted, thereby reducing the process cost.

Claims (12)

Sequentially depositing a first metal layer and a second metal layer on the substrate; Applying a resist film on the second metal layer; Patterning the resist film to form a resist pattern; Forming a gate electrode by wet-etching a first metal layer and a second metal layer simultaneously using an alkali mixed solution of ozone water and TMAH solution using the resist pattern as a mask; Forming a gate insulating film on the substrate including the gate electrode; Forming a source electrode and a drain electrode on the active layer on both sides of the gate insulating layer and on the gate insulating layer corresponding to the gate electrode; Thin film transistor manufacturing method comprising a. The method of claim 1, The ozone water is a thin film transistor manufacturing method of the alkaline solution dissolved ozone in distilled water. The method of claim 2, The concentration of the ozone water is 10ppm or less thin film transistor manufacturing method. The method of claim 1, The TMAH solution is a thin film transistor manufacturing method diluted with distilled water. The method of claim 4, wherein The concentration of the TMAH solution is 2.38 mol% thin film transistor manufacturing method. The method of claim 1, The first metal layer is aluminum (Al) or aluminum neodymium (AlNd) thin film transistor manufacturing method. Depositing a conductive metal comprising aluminum on the substrate to form a first metal layer, and subsequently depositing molybdenum to form a second metal layer; Applying a resist film on the second metal layer; Patterning the resist film to form a resist pattern; Forming a gate electrode and a gate wiring by wet-etching a first metal layer and a second metal layer simultaneously with an alkaline mixed solution of ozone water and TMAH solution using the resist film pattern as a mask; Forming a first insulating layer on the substrate on which the gate wiring and the gate electrode are formed; Forming an active layer on the first insulating layer corresponding to the gate electrode; Forming a source electrode and a drain electrode on the active layer and a data line crossing the gate line to define a pixel area; Forming a second insulating layer on the substrate including the data line; Forming a transparent pixel electrode on the pixel region; Array substrate manufacturing method for a liquid crystal display device comprising a. The method of claim 7, wherein The concentration of the ozone water is 10ppm or less array substrate manufacturing method for a liquid crystal display device. The method of claim 7, wherein And the ozone water is an alkaline solution in which ozone is dissolved in distilled water. The method of claim 9, The concentration of the ozone water is 10ppm or less array substrate manufacturing method for a liquid crystal display device. The method of claim 7, wherein The TMAH solution is a method for manufacturing an array substrate for a liquid crystal display device distilled in distilled water. The method of claim 11, The concentration of the TMAH solution is 2.38 mol% array substrate manufacturing method for a liquid crystal display device.

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