KR20110118297A - Etchant for thin film transistor liquid crystal display - Google Patents

Abstract

The present invention relates to a patterning of multiple films made of a copper film and another metal, which is a metal wiring material for a gate, a source, and a drain electrode, which constitute a thin film transistor (TFT) of a thin film transistor liquid crystal display device. It relates to an etching composition for a thin film transistor liquid crystal display device. The etching composition of the present invention comprises 3 to 35% by weight of hydrogen peroxide, 0.1 to 5% by weight of oxidizing agent, 0.1 to 5% by weight of phosphate, 0.1 to 5% by weight of chelating agent, 0.001 to 5% by weight % Aldehyde derivative, 0.01 to 5% by weight of ammonium compound, 0.1 to 5% by weight of additives and water to the total weight of the total composition is characterized in that it comprises 100% by weight.

Description

Etch Composition for Thin Film Transistor Liquid Crystal Display {ETCHANT FOR THIN FILM TRANSISTOR LIQUID CRYSTAL DISPLAY}

According to an embodiment of the present invention, a photoresist is coated and exposed on a metal wiring material for a gate, a source, and a drain electrode constituting a thin film transistor (TFT) of a liquid crystal display, and then etched to obtain a desired pattern ( The present invention relates to an etching composition for a thin film transistor liquid crystal display device.

In general, the liquid crystal display includes a liquid crystal panel including a thin film transistor substrate, a color filter substrate, and a liquid crystal layer injected between the two substrates. Wiring is formed on the thin film transistor substrate to transmit a signal to the liquid crystal layer. The wiring of the thin film transistor substrate includes a gate wiring and a data wiring. Here, the gate wiring includes a gate line to which a gate signal is applied and a gate electrode of a thin film transistor, and the data wiring is insulated from the gate wiring and a drain electrode and a source constituting the data electrode of the thin film transistor to apply a data signal. An electrode. Such a wiring may be made of a metal single layer or an alloy single layer, but is often formed in multiple layers to compensate for the disadvantages of each metal or alloy and to obtain desired physical properties.

On the other hand, the process of forming the metal wiring on the substrate in the semiconductor device is typically a step by a metal film forming process by sputtering or the like, a photoresist forming process in a selective region by photoresist coating, exposure and development, and an etching process It comprises a washing process before and after an individual unit process. The etching process refers to a process of leaving a metal film in a selective region using a photoresist as a mask, and typically, dry etching using plasma or wet etching using an etching solution is used.

The resistance of the metal film used at this time is a factor that causes the electrical signal delay of the thin film transistor liquid crystal display device and has a direct effect on the high resolution and the panel size. In recent years, copper (Cu) has been in the spotlight as a metal wiring material having a low resistance value and having no large environmental problems in order to reduce the electrical signal delay of a thin film transistor liquid crystal display device.

However, copper has a disadvantage of poor adhesion with glass and silicon films, and thus it is difficult to use copper as a single copper film. Accordingly, a multi-layer film using copper as a main wiring metal film and excellent copper alloy, titanium, molybdenum or molybdenum alloy as a buffer metal film is used to compensate for the shortcomings of a single copper film. Among them, a particularly popular material was copper titanium film. The copper titanium double layer has a known etching solution and a number of new etching solutions have been published. However, due to the special chemical properties of the titanium film, the copper titanium double layer does not have an fluorine ion. When fluorine ions are included in the etching solution, the glass substrate and various silicon layers (passivation layer composed of a semiconductor layer and a silicon nitride film) are also etched and there are many elements that may be defective in the process.

Thus, research on molybdenum films, which are relatively weaker than titanium, is being spread. This is because a copper molybdenum film can make a film having properties similar to or better than those of a copper titanium film by controlling the thickness of copper and molybdenum well.

According to Patent Publication No. 1999-017836, it is disclosed that an etching solution of copper-containing multilayers is a mixture of phosphoric acid, nitric acid, and acetic acid, and according to Publication 2000-0032999, iron chloride ( III) discloses a mixed material of hexahydrate and hydrofluoric acid. However, when the copper molybdenum film is etched using these etching solutions, the etching rate is too fast, which causes a problem in the process margin, and the taper angle of the taper profile has a value of 90 degrees or larger. The process becomes difficult, and the linearity of the pattern is also poor. In addition, in order to etch the multi-layer, as shown in the Patent Publication 1020060099089, the permeate-based etchant is mainly used because the permeate-based etchant contains a fluoride, causing a problem of etching the glass substrate has a problem of limiting the reuse of the glass substrate when a defect occurs during the panel manufacturing process. have.

Although copper (Cu) has been spotlighted as a metal wiring material, copper has a disadvantage in that adhesive strength with glass and silicon films is poor, so it is difficult to use a single copper film. Therefore, multiple films using copper as the main wiring metal film and excellent copper alloy, molybdenum or molybdenum alloy as the buffer metal film have been used to compensate for the shortcomings of the single copper film. In order to etch such multilayers, the permeate etchant contains fluoride, which causes the etching of the glass substrate, thereby limiting the reuse of the glass substrate when defects occur during the panel manufacturing process.

The present invention does not use a fluoride in the permeate-based etchant, it is possible to batch etching of a multi-layer consisting of a copper film and another metal film, an etching composition having an etching rate, an appropriate etching amount and an appropriate taper angle suitable for the process To develop.

In order to solve the above problems, the present invention provides an etching composition for a thin film transistor liquid crystal display device comprising a mixture of hydrogen peroxide, oxidizing agent, phosphate, chelating agent, aldehyde compound, ammonium compound and additives.

More specifically, the etching composition according to the present invention is 3 to 35% by weight of hydrogen peroxide, 0.1 to 5% by weight of oxidizing agent, 0.1 to 5% by weight of phosphate, 0.1 to 5% by weight of chelating agent, 0.001 to 5% by weight of aldehyde derivative, ammonium Appropriate etching rates, etching amounts and taper tilt angles are provided when water is mixed such that 0.01-5% by weight of the compound, 0.1-5% by weight of the additive and the total weight is 100% by weight.

In the present invention, the hydrogen peroxide serves to oxidize copper to form copper oxide (CuO ₂ ), when the content of hydrogen peroxide in the total composition is 35% by weight or more, causing an etching profile defect due to excessive etching of metal wiring, If the content of hydrogen peroxide is less than 3% by weight, the etching ability is weak, there is a limit to the smooth etching of the metal wiring.

The oxidizing agent according to the present invention may be selected from the group consisting of potassium hydrogen sulfate, sodium nitrate, ammonium sulfate, sodium sulfate and sodium hydrogen sulfate. The oxidant replaces copper oxide produced by hydrogen peroxide with copper nitrate (Cu (NO ₃ ) ₂ ) and copper sulfate (CuSO ₄ ), wherein the produced compound may be dissolved in an etching composition with water solubility. The oxidizing agent may include 0.1 to 5 wt% with respect to the total weight of the total composition, and when less than 0.1 wt%, the oxidizing agent may not be smoothly etched when the copper film, the copper alloy film or the multilayer film they are etched.

In the present invention, the chelating agent is characterized in that the organic chelating agent containing an amino group and a carboxyl group. The organic chelating agent is characterized in that at least one of ethylenediaminetetraacetic acid (EDTA), iminodiacetic acid, nitrilotriacetic acid (ditritritriacetic acid) and diethylene trinitrilo pentaacetic acid (DTPA) . When the chelating agent increases the number of etching treatments of the metal wiring to be etched, the chelating agent increases the ion of copper or metal in the etching solution, thereby preventing the etching ability from deteriorating. The chelating agent may include 0.1 to 5% by weight with respect to the total weight of the total composition, when exceeding 5% by weight leads to a threshold that no longer affects, and also has a poor solubility to precipitate It may have, if contained in less than 0.1% by weight does not prevent the phenomenon that the etching ability is lowered when the treatment proceeds. Therefore, the preferred composition range is 0.1 to 5% by weight is appropriate.

The phosphate added in an amount of 0.1 to 5% by weight relative to the total weight of the total composition includes ammonium monophosphate, ammonium dihydrogen phosphate, sodium dihydrogen phosphate and dihydrogen phosphate. Compounds characterized in that hydrogen in phosphoric acid, such as potassium dihydrogen phosphate, is selected from one, two or three substituted salts of ammonium or alkali and alkaline earth metals, are all applicable, alone or in combination of two or more It can be used as a mixture. Phosphate does not directly affect the etching characteristics, but maintains the constant concentration of hydrogen ions participating in copper oxidation by hydrogen peroxide solution, thus maintaining the etching characteristics after initial etching of a large number of substrates. . However, when the content of the phosphate is too high, the etching rate is lowered, so that it is difficult to apply the process.

In the present invention, the aldehyde derivative may be used to control the residue of the metal film in the etching solution, and may be selected from the group consisting of glutaraldehyde derivatives, formaldehyde derivatives, acetaldehyde derivatives and benzaldehyde derivatives. The aldehyde derivative may include 0.001 to 5% by weight based on the total weight of the total composition, and serves to control the taper profile of the metal film. Lose. If the above range is exceeded, the taper profile is sharply lowered to generate an upper undercut. If an amount smaller than the above range is used, the ability to adjust the taper profile is not expressed.

The ammonium compound is characterized in that the organic ammonium, including an ammonium group, inorganic ammonium. The ammonium compound dissociates in water and penetrates into the photoresist denatured into ions, thereby removing the dopant ions penetrated during the dry etching process in the photoresist.

In addition, when copper is used as the main wiring metal film and copper alloy, molybdenum or molybdenum alloy having excellent adhesion to glass and silicon films is used as a buffer metal film, residues are formed on the surface after etching unless it contains fluoride. Cause problems. The ammonium compound helps to control the pH of the etchant and the etching of molybdenum or molybdenum alloy to etch without residue even without using fluoride. If the additive ammonium compound is less than 0.01% by weight, the residue of the metal film may not be completely solved, thereby preventing the formation of wires of the metal film uniformly. In the case of more than 5% by weight, undercut of the lower molybdenum may be caused by a rise in pH, and a safety problem may occur when the treatment proceeds due to a sharp rise in pH.

The ammonium compound is characterized by consisting of at least one of ammonium acetate, ammonium nitrate, ammonium citrate, ammonium persulfate, ammonium chloride and ammonia water.

The present invention may include an additive, without being particularly limited, various kinds are possible, and as the preferred example, an azole compound which may be used as an etching inhibitor of a copper film may be used. The azole compound may be added in an amount of 0.1 to 5% by weight based on the total weight of the total composition, and may be used for controlling the etching rate and etching amount of copper or copper alloy. Examples of the azole compound include 5 amino tetrazole, 1,2,3 benzotriazole, methyl benzotriazole, imidazole and the like. If the additive contains less than 0.1% by weight, the loss due to etching (CD, Critical Dimension) may be large, and if it contains more than 5% by weight, the etching rate of copper or copper alloy may only be slowed. But the taper inclination angle can be non-uniform. In the present invention, the remaining amount of the total composition may be mixed with water, and may serve to dilute the etching composition.

When the etching process is performed with the etching composition according to the present invention, the loss due to etching is 1.0 μm or less, the taper inclination angle is 30 ° or more, and residues do not occur, thereby effectively etching.

The etching composition according to the present invention is a patterning of a copper film, which is a main wiring material of a gate electrode and a source / drain, constituting a thin film transistor liquid crystal display (TFTLCD). Can be used for

The etching composition according to the present invention can uniformly etch a copper film, a copper alloy film, a molybdenum film, a molybdenum alloy film, or a multilayer film in which they are stacked, and does not contain fluoride, so that the organic substrate is not etched. It can be reused to minimize material loss.

FIG. 1 is a photograph illustrating observing a profile of a molybdenum film / copper film after etching with an etching composition according to Example 1 of the present invention.
FIG. 2 is a photograph showing an electron microscope of a glass film after stripping of a photoresist (PR) of a molybdenum film / copper film after an etching process with an etching composition according to Example 1. FIG.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, embodiments of the present invention may be modified in various forms, and the scope of the present invention should not be construed as being limited by the embodiments described below.

[ Example 1 ]

15% by weight hydrogen peroxide, 1% by weight potassium hydrogen sulfate, 1% by weight ammonium phosphate monobasic, 1% by weight chelating agent, 1% by weight formic acid, 1% by weight ammonium citrate, 0.5% by weight 5-aminotetrazole as an additive, Water was mixed up to 100% by weight to prepare an etching composition.

Components and contents of the etching composition are shown in Table 1 below.

[ Example  2 to 4]

As in Example 1, only the composition ratio of the etching composition was changed to prepare an etching composition in the same manner.

Components and contents of the etching composition are shown in Table 1 below.

[ Comparative example  1 to 4]

The same process as in Example 1, but was prepared by mixing with the components and contents shown in Table 2.

[ Test Example ]

Etching process

Using the etching compositions of Examples 1 to 4 and Comparative Examples 1 to 4 prepared above, an etching process was performed on a multilayer film in which a copper film and a molybdenum film were laminated at a temperature of 30 ° C., respectively. Next, a method of manufacturing a liquid crystal display device using the etching solution according to the present invention for forming a gate wiring, a gate electrode, a data wiring, and a source / drain electrode will be described.

After depositing a first copper / molybdenum film on the substrate, a first photosensitive film pattern is formed on the first copper / molybdenum film by a photolithography process. Next, the first copper / molybdenum film is etched with the etching solution according to the present invention using the first photoresist pattern as a mask to form a gate line having one direction, and a gate electrode protruding from the gate line. Deposit. Thereafter, a semiconductor layer is deposited on the entire surface including the gate insulating layer, and then a predetermined region is patterned to form an active layer.

Next, after depositing a second copper / molybdenum film on the entire surface of the substrate, a second photoresist film pattern is formed on the second copper / molybdenum film by a photolithography process, and the second copper / mol is used as an etching solution according to the present invention. The metal layer is etched to form a pixel region by vertically crossing the gate line to form a pixel area, a source electrode protruding from one side of the data line, and a drain electrode spaced apart from the source electrode by a predetermined distance.

In the etching process, the physical properties of the glass substrate were exceeded by 100% from the end point detection (EPD, End Point Detect). At this time, the reason for the excess etching exceeding 100% is that the etching rate of the other metal film is relatively slow compared to the copper film so that the tail and the residue of the other metal film can be sufficiently removed.

Property evaluation

Examples 1 to 4 and Comparative Examples 1 to 4 by the following method to measure the etch loss, inclination angle and stability and the results are shown in Table 1 or Table 2. The etching loss was evaluated as "excellent" when the thickness was 0.5 µm ± 0.2 µm or less, "excellent" when the inclination angle was 30 degrees or more and 70 degrees or less, and "excellent" that no residue of the metal film was found.

FIG. 1 is a photograph of etched copper / molybdenum film with an etching composition according to Example 1 of the present invention and then observing a profile with an electron microscope.

2 is a photograph of the copper / molybdenum film as an etching composition according to Example 1, followed by stripping a photoresist (PR, Photo resist), and observed with an electron microscope, and a tail of the molybdenum film No residue is visible

[ Etch Loss Measurement ]

The profile of the molybdenum film etched by the etching process and the multilayer film (copper / molybdenum film) on which the copper film is laminated is observed using an electron microscope (SEM, Hitachi S4700) and photoresist. The distance between the tip and the tip of the copper film was measured and expressed as an etch loss measurement.

[Inclination angle measurement]

The profile of the multilayer film (copper / molybdenum film) in which the etched titanium film and the copper film are laminated by the etching method is observed using an electron microscope (SEM, Hitachi S4700), The value of the inclination angle was measured to indicate the inclination angle.

[ Residue measurement ]

After the PR is removed using a PR (photoresist) stripper, the multilayer film (copper / molybdenum film) in which the titanium film and the copper film are etched through the etching process is removed, and the middle film (copper / After removing the PR using a (photoresist) stripper, (Profile) was shown as a residue measurement by observing the wiring surface using an electron microscope (SEM, Hitachi S-4700).

Claims (9)

An etching composition for a thin film transistor liquid crystal display device comprising hydrogen peroxide, an oxidizing agent, a phosphate, a chelating agent, an aldehyde derivative, an ammonium compound, and an additive. The method of claim 1
Hydrogen peroxide 3 ~ 35%, Oxidizer 0.1-5%, Phosphate 0.1-5%, Chelating agent 0.1-5%, Aldehyde derivative 0.001-5%, Ammonium compound 0.01-5%, Additive 0.1-5% An etching composition for a thin film transistor liquid crystal display device comprising water and a total weight of 100% by weight. The method of claim 1
The oxidizing agent is an etching composition for a thin film transistor liquid crystal display device selected from potassium hydrogen sulfate, sodium nitrate, ammonium sulfate, sodium sulfate or sodium hydrogen sulfate. The method of claim 1,
Wherein the phosphate is a compound selected from ammonium monophosphate, ammonium dihydrogen phosphate, sodium dihydrogen phosphate or potassium dihydrogen phosphate, or a mixture of two or more selected from the same. The method of claim 1,
The chelating agent is an etching composition for a thin film transistor liquid crystal display device selected from EDTA, imino diacetic acid, nitrilo triacetic acid or diethylene trinitrilo pentaacetic acid (DTPA). The method of claim 1,
The aldehyde derivative is an etching composition for a thin film transistor liquid crystal display device selected from glutaraldehyde derivatives, formaldehyde, acetaldehyde derivatives or benzaldehyde derivatives. The method of claim 1,
The additive is an etch composition for a thin film transistor liquid crystal display device selected from an azole compound which is 5-aminotetrazole, 1,2,3-benzotriazole, methylbenzotriazole and imidazole. The method of claim 1,
The ammonium compound is an etching composition for a thin film transistor liquid crystal display device selected from ammonium acetate, ammonium nitrate, ammonium citrate, ammonium chloride or ammonia water. The method of claim 1,
The composition is an etching composition for a thin film transistor liquid crystal display device applied to a copper film, a copper alloy film, a molybdenum film, a molybdenum alloy film or a multi-layer laminated film.

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