JP2009076910A - Etching fluid composition for metal wiring formation for tft-lcd - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an etching fluid composition for metal wiring formation for TFT-LCD. <P>SOLUTION: Disclosed is the etching fluid composition containing 55 to 75% by mass of phosphorous acid, 0.75 to 1.99% by mass of nitric acid, 10 to 20% by mass of acetic acid, 0.05 to 0.5% by mass of an Mo etching conditioner, 0.02 to 3% by mass of a boron-containing compound, and water for the rest based on the entire mass of the composition. An etching profile in a superior tapered shape can be obtained without undercutting nor projection phenomenon by wet-etching an Mo/AlNd double film or an Mo/Al/Mo triple film as gate and source/drain wiring materials in a single process, and a dry etching process is excluded to make processes smooth for improved productivity, thereby lowering manufacturing costs. Further, an environmentally harmful substance such as perchloric acid, an unstable component shortening the life of etching fluid, or a fluorine-based compound which corrodes glass of a substrate is unneeded. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

The present invention relates to a thin film transistor liquid crystal display (TFT-LCD).
More specifically, an etching solution composition used for etching a metal layer for an electrode of a transistor-liquid crystal display (Mo / AlNd double film or Mo / Al / Mo triple film) which is a gate and source / drain wiring material It is related with the etching liquid composition which can provide the taper-shaped etching profile excellent without undercut and a protrusion phenomenon by carrying out wet etching in a single process.

  Liquid crystal display devices (LCD devices) are the most common flat panel display devices because they provide clear images with excellent resolution, low power consumption, and thin display screens. Attention has been paid. At present, a typical electronic circuit for driving such a liquid crystal display element is a thin film transistor (TFT) circuit, and a typical thin film transistor liquid crystal display (TFT-LCD) element has a pixel on a display screen. Is formed. The TFT-LCD element is a TFT-LCD element manufactured by filling a liquid crystal substance between a TFT substrate arranged in a matrix and a color filter substrate facing the TFT-LCD element. is there. The entire TFT-LCD manufacturing process is roughly divided into a TFT substrate manufacturing process, a color filter process, a cell process, and a module process. In order to obtain an accurate and clear image, the TFT substrate and the color filter manufacturing process. Is very important.

  Aluminum (Al) or Al alloy is often used as a TFT gate and source / drain electrode wiring material in the TFT substrate manufacturing process. Specifically, molybdenum (Mo) and Al pure gold or alloy, respectively. For example, a double layer composed of Mo and Al-neodymium (Nd) or a triple layer of Mo / Al / Mo is laminated on the substrate. In order to form a desired electric circuit line on these metal layers, an etching process is required to cut the metal layers according to the circuit pattern. Since many thin film layers are stacked on the TFT substrate, in order to prevent an undesired electrical short circuit between them, the cut side surface of the etched metal layer, that is, the etching profile is uniformly inclined. It is desirable that the lower part is a gentle taper shape wider than the upper part. The reason is that if the etching profile has a gentle taper shape, the steps between the formed thin film layers are reduced. In practice, when the etching pattern of the gate metal layer is not uniform and not precise, the resolution of the TFT-LCD image is lowered and the hue is not accurate.

Examples of the etching method include a wet etching method and a dry etching method.
The wet etching method is an isotropic etching in which etching is uniformly performed in all directions, so that it is not used for manufacturing a shape of 3 μm or less, and there is a disadvantage that the cost of an etching solution (etchant) and deionized water is high. The equipment investment cost for the process is low, the etching environment does not need to be maintained in a high vacuum state, and both the mask and the substrate are excellent in etching selectivity. In the case of a wiring material for an aluminum alloy electrode, a mixed acid etching solution of phosphoric acid-nitric acid-acetic acid has been widely used. In mixed acid etchant, nitric acid functions to oxidize aluminum to aluminum oxide and molybdenum to molybdenum oxide, acetic acid functions as a buffer solution to adjust the reaction rate, phosphoric acid functions as aluminum oxide and molybdenum oxide. The function to dissolve. However, phosphoric acid has a problem of high cost and high viscosity.
On the other hand, the dry etching method is an anisotropic etching method, and its greatest advantage is that etching of a structure of 3 μm or less is possible. However, it requires high-cost vacuum equipment and is physically dry etching. The law has the disadvantage of poor selectivity.

  With only one conventional wet etching, it is difficult to obtain an excellent etching profile, that is, a tapered etching profile without undercut phenomenon, in which aluminum in the lower metal layer is etched more than the molybdenum layer. When undercut occurs, a method of adding dry etching to etch the protruding molybdenum layer has been used, but this has a problem in that productivity is lowered due to process delay and cost increase. Therefore, in this technical field, various attempts have been made to develop a method capable of obtaining an excellent etching profile by only one wet etching using an etching solution having a low cost and high selectivity.

In contrast, Patent Document 1 discloses an etching containing nitric acid, iron nitrate, and 1-4% by mass of perchloric acid (HClO ₄ ) as an oxidizing agent as a composition for etching a Mo / AlNd bilayer in a single step. Presenting liquid. However, since perchloric acid can be a source of chlorine radicals (Cl ⁻ ) that destroy the stratospheric ozone layer, it is classified as an environmental hazardous substance and its use is restricted. In addition, perchloric acid has a problem that it is difficult to use perchloric acid together with other components by depositing unnecessary substances such as residues on the substrate. Hydrogen peroxide has good oxidizing power and helps in etching of indium tin oxide (ITO) films, but it makes the etching solution unstable and shortens the life of the etching solution. As a result, the cost increases. Patent Document 2 discloses an etching solution comprising 10 to 50% nitric acid, 5 to 30% acetic acid, 0.1 to 5% fluorine-containing compound, and 0.1 to 5% boron-containing compound based on the mass ratio. However, this patented invention has a problem that the glass of the substrate is corroded by the use of the fluorine-based compound, and the browning phenomenon occurs when the iron (Fe) series compound is used.
Korean Patent Application No. 2003-70738 Specification Korean registered patent No. 598418 specification

  The present invention provides an excellent taper for a metal layer such as a Mo / AlNd double film or a Mo / Al / Mo triple film widely used as a wiring material for gate and source / drain electrodes by only one wet etching process. It is an object of the present invention to provide an etchant composition that does not contain environmentally harmful substances, unstable components that shorten the life of the etchant, or fluorine compounds that corrode the glass of the substrate. .

  In order to solve the above problems, the present invention is based on the mass of the etching solution composition, phosphoric acid 55-75 mass%, nitric acid 0.75-1.99 mass%, acetic acid 10-20 mass%, Mo etching adjustment Provided is an etching solution composition containing 0.05 to 0.5% by mass of an agent, 0.02 to 3% by mass of a boron-containing compound, and the balance of water.

In the etching solution composition of the present invention, the Mo etching modifier is MH ₂ PO ₄ , M ₂ HPO ₄ , M ₃ PO ₄ , MHSO ₄ , M ₂ SO ₄ , CH ₃ COOM, MHCO ₃ , M ₂ CO _3. , MNO ₃ and M ₂ C ₂ O ₄ (wherein M is NH 4, Na or K), one or more salt compounds selected from the group consisting of KNO ₃ , CH ₃ COOK, One or more substances selected from the group consisting of NH ₄ NO ₃ , CH ₃ COONH ₄ , KH ₂ PO ₄ , (NH ₄ ) H ₂ PO ₄ and KHSO ₄ , in particular, KNO ₃ or It is characterized by being CH ₃ COONH ₄ .

In the etching solution composition of the present invention, the boron-containing compound is a compound that dissociates in the etching solution composition to form boron ions or ions containing boron, and is characterized in that H ₃ BO ₃ , B ₂ O ₂ , B ₂ O ₃ , B ₄ O ₃ , B ₄ O ₅ , KBO ₂ , NaBO ₂ , HBO ₂ , H ₂ B ₄ O ₇ , Na ₂ B ₄ O ₇ .10H ₂ O, KB ₅ O ₈ -One or more substances selected from the group consisting of 4H ₂ O, BN, BF ₃ , BCl ₃ and BBr ₃ , especially boric acid (H ₃ BO ₃ ) To do.

  If the etching liquid composition for TFT-LCD of the present invention is used, the Mo / AlNd double film or the Mo / Al / Mo triple film, which is the gate and source / drain wiring material, is wet-etched in a single step, and AlNd is obtained. It is possible to provide an excellent tapered etching profile without undercutting and protruding phenomenon of Al or Mo. Further, by eliminating the dry etching process, the process can be smoothed to improve the productivity, and the production cost can be reduced. Even if it does not contain environmentally hazardous substances such as perchloric acid, unstable components that shorten the lifetime of the etching solution, or fluorine-based compounds that corrode the glass of the substrate, the Mo / AlNd double film or Mo / Al An excellent taper-shaped etching profile can be obtained by only one wet etching process with respect to the / Mo triple film.

Hereinafter, the present invention will be described in more detail.
The etching solution composition of the present invention is 55 to 75% by mass of phosphoric acid, 0.75 to 1.99% by mass of nitric acid, 10 to 20% by mass of acetic acid, and Mo etching modifier 0 with respect to the mass of the whole etching solution composition 0.05 to 0.5% by mass, 0.03 to 3% by mass of a boron-containing compound and the remaining amount of water.

  Mo etching modifier is a deviation caused by the difference in oxidation tendency between aluminum and molybdenum layer by selectively adjusting the etching rate of molybdenum in the batch etching process of Mo / AlNd double layer or Mo / Al / Mo triple layer. Is an additive that prevents etching and etches to an appropriate etching profile, and uses an ammonium salt and an alkaline earth metal (sodium or potassium or lithium) salt as a Mo etching modifier. The mechanism is as follows. is there.

Monovalent alkali ions ammonium salts and alkaline earth metal (sodium or potassium or lithium) salt, at the surface of the molybdenum film molybdenum (Mo) and _M 2 O · MoO ₃ or _M 2 O · 2MoO _{3 (M} is NH ₄ Or, it has a fine reaction force to form a hardly soluble molybdenum composite oxide of Na or K), and lowers the molybdenum etching reaction rate at which molybdenum changes to MoPO ₄ . Further, the adhesion between the photoresist and the metal is reduced in the metal layer, and the etching profile of the metal layer is excellent even in wet etching, and the residue is reduced.

  At this time, when the content of the Mo etching modifier is less than 0.05% by mass, the molybdenum etching reaction rate does not decrease, and the upper part of the Mo / AlNd double film and the Mo / Al / Mo, Mo / AlNd / Mo triple film. Mo forms a staircase profile, and an undercut phenomenon occurs in the lower Mo. When the content of the Mo etching modifier is more than 0.5% by mass, the molybdenum etching reaction rate becomes excessively slow, and the Mo / AlNd double film and the Mo / AlNMo, Mo / AlNd / Mo triple film A phenomenon occurs in which the upper and lower Mo protrude.

Mo etch modifiers include MH ₂ PO ₄ , M ₂ HPO ₄ , M ₃ PO ₄ , MHSO ₄ , M ₂ SO ₄ , CH ₃ COOM, MHCO ₃ , M ₂ CO ₃ , MNO ₃ , M ₂ C ₂ O ₄ using one or more salt compounds selected from the group consisting of ammonium, sodium and potassium salt compounds in the form of ₄ (M is NH ₄ , Na or K), in particular KNO ₃ , CH ₃ COOK, NH ₄ NO ₃ , CH ₃ COONH ₄ , KH ₂ PO ₄ , (NH ₄ ) H ₂ PO ₄ or KHSO ₄ is used, preferably KNO ₃ or CH ₃ COONH ₄ is used.

  Nitric acid oxidizes aluminum to aluminum oxide and acts to etch molybdenum. At this time, when the content of nitric acid is more than 1.99% by mass, the stepped profile in which Mo / AlNd double film and Mo / Al / Mo, Mo / AlNd / Mo triple film upper Mo are excessively contained. Undercut phenomenon occurs in the lower Mo. When the content of nitric acid is less than 0.75% by mass, a phenomenon in which upper and lower molybdenum protrude in the Mo / AlNd double film, the Mo / Al / Mo, and Mo / AlNd / Mo triple films occurs.

  Phosphoric acid acts to dissolve the aluminum oxide. When the phosphoric acid content is less than 55% by mass, the etching rate of aluminum becomes slow, and the upper Mo forms a stepped profile and the lower Mo forms an undercut in the triple film. When the content of phosphoric acid is more than 75% by mass, the etching rate of aluminum becomes excessively high, causing a phenomenon that upper / lower Mo protrudes, and the viscosity of the etching solution increases due to the high viscosity of phosphoric acid. Therefore, there arises a problem that the etching uniformity is lowered.

  Acetic acid acts as a buffer solution that adjusts the reaction rate, but when the acetic acid content is less than 10% by mass, the etching solution life is shortened due to the lack of buffering agent, and the etching solution viscosity increases, resulting in uniform etching. Sex is reduced. On the other hand, when the content is more than 20% by mass, the etching reaction rate of molybdenum becomes slow, and the Mo / AlNd double film and Mo / Al / Mo, and the upper and lower Mo of the Mo / AlNd / Mo triple film protrude. Will occur.

The boron-containing compound improves the productivity by suppressing the etching rate and makes it possible to secure a process margin. When the boron-containing compound content is less than 0.02% by mass, the etching rate of aluminum is improved, the change in the etching profile due to over-etching is severed, the process margin is difficult to secure, and the productivity is reduced. . When the content of the boron-containing compound is more than 3% by mass, the solubility of other compounds in the etching solution is lowered, and the etching rate of the metal film is made very slow. Examples of the boron-containing compound include H ₃ BO ₃ , B ₂ O ₂ , B ₂ O ₃ , B ₄ O ₃ , B ₄ O ₅ , KBO ₂ , NaBO ₂ , HBO ₂ , H ₂ B ₄ O ₇ , Na _2. It is selected from the group consisting of B ₄ O ₇ · 10H ₂ O, KB ₅ O ₈ · 4H ₂ O, BN, BF ₃ , BCl ₃ , and BBr ₃ , and preferably boric acid (H ₃ BO ₃ ) is used.

Further, the etching solution of the present invention is an aqueous solution, and the remainder with respect to the sum of the mass ratios of the essential components essentially contains water so that the total mass ratio becomes 100%. The water used at this time is preferably ultrapure water.
As a result, an excellent tapered etching profile can be obtained by using the etching solution composition of the present invention.

  Hereinafter, the present invention will be described in more detail with reference to examples. The configurations shown in the following examples are only for helping understanding of the invention, and in any case, the technical scope of the present invention is not limited to the embodiments shown in the examples.

An etchant composition was produced according to the composition shown in Table 1 below. CH ₃ COONH ₄ was used as the Mo etching modifier, and H ₃ BO ₃ was used as the boron-containing compound.

(Test example)
The etching performance of the manufactured Example 1 and Comparative Examples 1 to 5 was compared. Specifically, the etching process is performed within 2 minutes by spraying 10 L of an etching solution with a spray circulation type simple equipment onto a 10 cm × 10 cm substrate on which a Mo / AlNd double film and a Mo / Al / Mo triple film are laminated. It was. Etching performance was evaluated by observing the etched substrate with an electron microscope. 1 to 5 are photographs of each of the substrates that have been etched using the etching solutions of Example 1 and Comparative Examples 1 to 4 observed with an electron microscope.

  According to FIG. 1, when etched with the etching solution of Example 1 of the present invention, it represents an excellent taper etching profile for the Mo / AlNd double film and the Mo / Al / Mo triple film. Can be confirmed. As the double film, the molybdenum upper layer is shaved more than the lower aluminum layer, and the inclination of the bimetallic layer is also appropriate, so it can be seen that it is excellently tapered, and even in the triple film, the upper molybdenum layer is more than the aluminum layer It can be confirmed that the lower molybdenum layer is scraped less than the aluminum layer and has an excellent taper shape.

  According to FIG. 2, when etched with the etching solution of Comparative Example 1, since the phosphoric acid content is less than the range of the present invention, the etching rate of aluminum becomes slow, and in the double film, the molybdenum layer is In the triple film, it can be confirmed that the upper Mo forms a stepped profile and the lower Mo forms an undercut. The stepped etching result increases the risk of an electrical short circuit, which causes a deterioration in the image quality of the TFT-LCD.

  According to FIG. 3, when etched with the etching solution of Comparative Example 2, the content of nitric acid is larger than the range of the present invention, so that the upper Mo of the Mo / AlNd bilayer film and the Mo / Al / Mo trilayer film. Can be confirmed that an undercut phenomenon has occurred in the lower Mo.

  According to FIG. 4, when etching is performed with the etching solution of Comparative Example 3, since the content of acetic acid as a buffer solution is larger than the range of the present invention, the etching reaction rate of molybdenum becomes slow, and Mo / AlNd 2 It can be confirmed that the phenomenon in which the Mo layer of the heavy film and the upper and lower Mo of the Mo / Al / Mo trilayer protrude is generated.

  According to FIG. 5, when etching is performed with the etching solution of Comparative Example 4, the Mo etching modifier content is larger than the range of the present invention, so that the molybdenum etching reaction rate becomes excessively slow, and Mo / AlNd 2 It can be confirmed that the phenomenon in which the Mo layer of the heavy film and the upper and lower Mo of the Mo / Al / Mo trilayer protrude is generated.

  On the other hand, when etched with the etching solution of Comparative Example 5, since the content of the boron-containing compound is larger than the range of the present invention, the etching reaction rate is remarkably reduced as shown in Table 2 below.

  Although the present invention has been described in detail with reference to preferred embodiments and comparative examples, it is intended to be exemplary only, and various modifications and equivalent other embodiments may be made by those skilled in the art. You will see that. Therefore, the true technical protection scope of the present invention must be determined by the technical idea of the claims.

  The present invention is applicable to technical fields related to semiconductor substrate manufacturing.

It is the photograph which measured the profile of the Mo / AlNd double film | membrane and Mo / Al / Mo triple film | membrane before removing a photoresist after wet-etching with the etching liquid by this invention with the electron microscope. The profile of the Mo / AlNd double film and the Mo / Al / Mo triple film before the photoresist is removed after wet etching with an etching solution containing phosphoric acid in an amount less than the phosphoric acid content of the etching solution according to the present invention. It is the photograph measured with the microscope. The profile of the Mo / AlNd double film and the Mo / Al / Mo triple film after wet etching with an etching solution containing nitric acid in an amount larger than the nitric acid content of the etching solution according to the present invention and before removing the photoresist is observed with an electron microscope. It is the measured photograph. The profile of the Mo / AlNd double film and the Mo / Al / Mo triple film after wet etching with an etching solution containing acetic acid in an amount larger than the acetic acid content of the etching solution according to the present invention and before removing the photoresist is observed with an electron microscope. It is the measured photograph. The Mo / AlNd double film and the Mo / Al / Mo triple layer after wet etching with an etchant containing an amount of Mo etch modifier greater than the Mo etch modifier content of the etchant according to the present invention and before removing the photoresist It is the photograph which measured the profile of the film | membrane with the electron microscope.

Claims (7)

  55-75 mass% phosphoric acid, 0.75-1.99 mass% nitric acid, 10-20 mass% acetic acid, 0.05-0.5 mass% Mo etching modifier, based on the total mass of the etching solution composition, An etching solution composition comprising 0.02 to 3% by mass of a boron-containing compound and the remaining water. The Mo etch modifier is MH ₂ PO ₄ , M ₂ HPO ₄ , M ₃ PO ₄ , MHSO ₄ , M ₂ SO ₄ , CH ₃ COOM, MHCO ₃ , M ₂ CO ₃ , MNO ₃ and M ₂ C ₂ O. _4. The etching solution composition according to claim 1, wherein the etching solution composition is one or more salt compounds selected from the group consisting of ₄ (wherein M is NH ₄ , Na, or K). The Mo etch modifier is one or more selected from the group consisting of KNO ₃ , CH ₃ COOK, NH ₄ NO ₃ , CH ₃ COONH ₄ , KH ₂ PO ₄ , (NH ₄ ) H ₂ PO ₄ and KHSO _4. The etching solution composition according to claim 1, wherein The etchant composition according to claim 1, wherein the Mo etching regulator is KNO ₃ or CH ₃ COONH ₄ .   2. The etching solution composition according to claim 1, wherein the boron-containing compound is a compound that dissociates in the etching solution composition to form boron ions or ions containing boron. 3. The boron-containing compounds are H ₃ BO ₃ , B ₂ O ₂ , B ₂ O ₃ , B ₄ O ₃ , B ₄ O ₅ , KBO ₂ , NaBO ₂ , HBO ₂ , H ₂ B ₄ O ₇ , Na ₂ B. _{4 O 7 · 10H 2 O,} KB 5 O 8 · 4H 2 O, BN, the BF 3, BCl ₃ and claim 5, characterized in that one or more materials selected from the group consisting of BBr ₃ The etching liquid composition as described. The etchant composition according to claim 6, wherein the boron-containing compound is H ₃ BO ₃ .

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