KR20090095408A - Etching solution composition for formation of metal line - Google Patents

Abstract

An etchant composites to form metal wiring is provided to secure the stability of the solution in the process progress and prevent the damage of an under layer. An etchant composites to form metal wiring comprises H3PO4 of 40~70 weight%, HNO3 of 2~10 weight%, CH3COOH of 5~20 weight%, phosphate of 0.1~5 weight%, rest compound having the amino radical of 0.1~5 weight% and carboxylic acid group, and water. The phosphate is the sodium dihydrogen phosphate and one kind or greater selected from the potassium dihydrogen phosphate. The compound having the amino radical and carboxylic acid group within one molecule is one selected from alanine series, aminobutyric acid series, glutamic acid series, glycine series, iminodiacetic acid series, nitrilotriacetic acid series and sarcosine series. The etchant composites more includes one or greater among the etching control, surfactant, scavenger, anticorrosive agent and pH adjusting agent.

Description

Etching liquid composition for forming metal wiring {ETCHING SOLUTION COMPOSITION FOR FORMATION OF METAL LINE}

The present invention relates to a wet etchant composition related to copper, and more particularly, to an etchant composition capable of etching a single layer composed of copper or a copper alloy and multiple layers formed of the above metals in a flat panel display device.

In general, the process of forming metal wiring on a substrate in a semiconductor device and a flat panel display device is typically a metal film forming process by sputtering, a photoresist forming process and an etching process in a selective region by photoresist coating, exposure and development. It consists of the steps by, and includes a washing process before and after the individual unit process.

The etching process refers to a process of leaving a metal film in a selective region using a photoresist mask, and typically, dry etching using plasma or wet etching using an etching solution is used.

In recent years, resistance of metal wiring has emerged as a major concern. Resistance is a major factor in inducing RC signal delay, especially in the case of TFT-LCD (thin film transistor-liquid crystal display), which is a key factor in increasing panel size and realizing high resolution.

Therefore, in order to realize the reduction of RC signal delay, which is essential for the large-sized TFT-LCD, low-resistance material development is essential, and chromium (Cr resistivity: 12.7 × 10 ^-8 Ωm), molybdenum ( Mo resistivity: 5 × 10 ⁻⁸ mm, aluminum (Al resistivity: 2.65 × 10 ⁻⁸ mm) and alloys thereof are difficult to use for gate and data wiring used in large-sized TFT-LCDs.

Under this background, there is a great interest in copper films or copper alloy films, which are one of new low resistance metal films. This is because the copper film is known to have an advantage that the resistance is significantly lower than that of the aluminum film or the chromium film and that there is no big problem in the environment.

As a food solution composition for a copper film or a copper alloy film, a mixture of a chlorinated compound and a fluorine-containing compound was used depending on the constituent conditions of the thin film. However, due to its disadvantages in practical processes, it is not used much at present. However, hydrogen peroxide water generally has a problem that when the metal (metal) is included, the decomposition reaction is caused by the metal as shown in the following reaction formula to become an unstable state.

Cu + 2H ₂ O ₂ → Cu ^{2 +} + 2H ₂ O + O ₂ ↑

In addition, although an etchant including oxone has been proposed as a copper film etchant, there are problems such as instability of oxone itself and a slow etching rate.

The present invention is to solve the problems of the prior art as described above, in etching a single film consisting of copper or a copper alloy and more than one double film made of the metal, the stability of the chemical solution is secured in the process, It is an object of the present invention to provide an etching liquid composition that exhibits excellent etching characteristics without damage to the film, exhibits uniform etching characteristics, can be applied to a large area substrate, and has no damage to equipment.

The present invention is based on the total weight of the composition, 40 to 70% by weight of H ₃ PO ₄ , 2 to 10% by weight of HNO ₃ , 5 to 20% by weight of CH ₃ COOH, 0.1 to 5% by weight of phosphate, 0.1 to 5% by weight of a compound having amino and carboxylic acid groups in one molecule, and the balance of water It provides an etching solution composition comprising.

The etching liquid composition of the present invention, in the etching of a single film consisting of copper or a copper alloy and a multi-layer or more of the double film consisting of the metals ensures the stability of the chemical solution in the process, there is no damage to the lower film, and exhibits uniform etching characteristics In addition, it can be applied to large area substrates and shows excellent etching characteristics without damage to equipment, contributing to productivity improvement.

The present invention is based on the total weight of the composition, 40 to 70% by weight of H ₃ PO ₄ , 2 to 10% by weight of HNO ₃ , 5 to 20% by weight of CH ₃ COOH, 0.1 to 5% by weight of phosphate, 0.1 to 5% by weight of a compound having amino and carboxylic acid groups in one molecule, and the balance of water It relates to an etching liquid composition comprising.

The etchant composition of the present invention is for wet etching a single film made of copper or a copper alloy and a multilayer of two or more films made of the above metals. The etchant composition of the present invention may be preferably used when simultaneously etching a single film composed of copper or a copper alloy and multiple films of at least two layers formed of the metals at the same time.

In the etchant composition of the present invention, the H ₃ PO ₄ serves to oxidize copper. The H ₃ PO ₄ is preferably included in 40 to 70% by weight relative to the total weight of the composition, when included in less than 40% by weight of the copper etch rate is lowered or non-uniform etching can not obtain the desired etching characteristics In the case of more than 70% by weight, it is difficult to control the process due to the excessive etching speed of copper, and the pattern line width of the copper film is narrowed by the excessive etching, so that a desired resistance characteristic value cannot be obtained.

In the present invention, the HNO ₃ serves to oxidize copper, it is preferably included in 2 to 10% by weight based on the total weight of the composition. When the HNO ₃ is included in less than 2% by weight, staining occurs due to a decrease in the etching speed of copper or an uneven etching phenomenon, and overetching of copper occurs when it exceeds 10% by weight.

Acetic acid in the present invention is included in the amount of 5 to 20% by weight based on the total weight of the composition as a component for oxidizing copper. When acetic acid is included in less than 5% by weight, the copper may not be etched smoothly, and thus a partial copper residue may occur in the substrate. When the amount of acetic acid is more than 20% by weight, copper may be over-etched to provide uniform etching characteristics. Difficult to get.

In the present invention, the phosphate is preferably contained in 0.1 to 5% by weight based on the total weight of the composition as a component for controlling the etching rate of copper. When the phosphate is contained in less than 0.1% by weight, it does not function properly as an etching rate control agent of copper, and when it exceeds 10% by weight, the etching rate of copper is rather slow, resulting in copper residue and non-uniform etching characteristics. Indicates.

The phosphate is preferably at least one selected from salts in which one to three hydrogens are substituted with alkali metals or alkaline earth metals in phosphoric acid. For example, sodium dihydrogen phosphate and potassium dihydrogen phosphate (potassium). dihydrogen phosphate) may be used one or more selected from.

In the present invention, the compound having an amino group and a carboxylic acid group in one molecule is preferably contained in an amount of 0.1 to 5% by weight relative to the total weight of the composition as a component for controlling the etching rate of copper. When the component is contained in less than 0.1% by weight it is impossible to control the etching rate of the copper may cause over-etching, if the content exceeds 5% by weight the copper etching rate is lowered and the etching time in the process is prolonged in productivity Can cause problems.

Examples of the compound having an amino group and a carboxylic acid group in one molecule include alanine series, aminobutyric acid series, glutamic acid series, glycine series, and iminodiacetic acid series. At least one selected from nitrilotriacetic acid series and sarcosine series compounds may be preferably used. In particular, imino-diacetic acid-based compounds can be preferably used.

In the present invention, the water is not particularly limited, but deionized water is preferable. In particular, it is more preferable to use deionized water having a specific resistance value of the water (that is, the degree of removal of ions in the water) of 18 kV / cm or more.

The etchant composition of the present invention may further include conventional additives in addition to the above-described components, and may be used as an additive, such as an etching regulator, a surfactant, a metal ion sequestrant, a corrosion inhibitor and a pH regulator.

The surfactant serves to lower the surface tension to increase the uniformity of the etching. Such surfactants are preferably surfactants that can withstand etching solutions and are compatible. Examples thereof include any anionic, cationic, zwitterionic or nonionic surfactant. Moreover, a fluorine-type surfactant can be used as surfactant.

In addition, the additive is not limited thereto, and in order to further improve the effects of the present invention, various other additives known in the art may be selected and added.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the following examples are intended to illustrate the present invention in more detail, and the scope of the present invention is not limited by the following examples, and those skilled in the art can be appropriately modified and changed within the scope of the present invention.

Example  1-10: Etchant  Preparation of the composition and Etching  Characteristic test

H ₃ PO ₄ , HNO ₃ , CH ₃ COOH, sodium dihydrogen phosphate, imino diacetic acid,  And water was mixed in the composition ratio shown in Table 1 below to prepare a 180 kg etching solution.

A Cu layer was deposited on the glass, and a substrate on which the photoresist was patterned into a predetermined shape was prepared. When the etching solution prepared above is put into a spraying etching experiment apparatus (manufactured by K, C Tech, model name: ETCHER (TFT)) and warmed by setting the temperature to 35 ° C, and the temperature reaches 35 ± 0.1 ° C. An etching process was performed. Total etch time was given at 50% based on EPD. Insert the prepared substrate, start spraying, and when the etching is complete, take out and wash with deionized water, dry using a hot air dryer, and remove the photoresist using a photoresist stripper. It was. After washing and drying, the items of EDP, CD (critical dimension) skew, taper angle, and etching residue were evaluated using an electron scanning microscope (SEM; manufactured by Hitachi, model name: S-4700), and the results are shown in Table 1. .

< Etching  Characteristic evaluation criteria>

◎: EPD ≤ 70sec, CD Skew ≤ 2㎛, taper angle 70-90 degrees

○: EPD ≤ 75 sec, CD Skew ≤ 3 μm, taper angle 60 to 70 degrees

△: EPD ≤ 80sec, CD Skew ≤ 4㎛, taper angle 50 to 60 degrees

×: EPD> 80 sec, CD Skew> 4 µm, taper angle <50 degrees

As shown in Table 1, when the Cu film was etched using the etchant compositions of Examples 1 to 10 according to the present invention, good etching was achieved in all evaluation items of EDP, CD (critical dimension) skew, taper angle, and etch residue. It can be seen that the characteristics are shown.

In addition, a scanning electron micrograph (FIG. 1) of the substrate surface photographed after etching the Cu film using the etchant composition according to Example 6 attached below, and the substrate surface photographed after stripping the photoresist from the etched substrate From the scanning electron micrograph (FIG. 2), it can be confirmed that the composition of the present invention has good etching characteristics.

Comparative example  1-5: Etchant  Preparation of the composition and Etching  Characteristic test

The components shown in Table 2 were mixed according to the corresponding composition ratios to prepare 180 kg of an etching solution.

A Cu layer was deposited on the glass, and a substrate on which the photoresist was patterned into a predetermined shape was prepared. When the etching solution prepared above is put into a spraying etching experiment apparatus (manufactured by K, C Tech, model name: ETCHER (TFT)) and warmed by setting the temperature to 35 ° C, and the temperature reaches 35 ± 0.1 ° C. An etching process was performed. Total etch time was given at 50% based on EPD. Insert the prepared substrate, start spraying, and when the etching is complete, take out and wash with deionized water, dry using a hot air dryer, and remove the photoresist using a photoresist stripper. It was. After washing and drying, the items of EDP, CD (critical dimension) skew, taper angle, and etching residue were evaluated using an electron scanning microscope (SEM; manufactured by HITACHI, model name: S-4700), and the results are shown in Table 2. .

< Etching  Characteristic evaluation criteria>

◎: EPD ≤ 70sec, CD Skew ≤ 2㎛, taper angle 70-90 degrees

○: EPD ≤ 75 sec, CD Skew ≤ 3 μm, taper angle 60 to 70 degrees

△: EPD ≤ 80sec, CD Skew ≤ 4㎛, taper angle 50 to 60 degrees

×: EPD> 80 sec, CD Skew> 4 µm, taper angle <50 degrees

As shown in Table 2, in the case of etching using the etchant composition of Comparative Examples 1 to 5, most of the evaluation items of EDP, CD (critical dimension) skew, taper angle, and etching residue were poor in etching characteristics, and thus the etchant was used. It can be seen that the composition is difficult to apply in the actual process.

1 is a scanning electron micrograph of a substrate surface photographed after etching a Cu film using the etchant composition according to Example 6 of the present invention.

FIG. 2 is a scanning electron micrograph of a substrate surface photographed after etching a Cu film and stripping a photoresist using the etchant composition according to Example 6 of the present invention.

Claims (6)

40 to 70 weight percent of H ₃ PO ₄ , based on the total weight of the composition, 2 to 10% by weight of HNO ₃ , 5 to 20% by weight of CH ₃ COOH, 0.1 to 5% by weight of phosphate, 0.1 to 5% by weight of a compound having amino and carboxylic acid groups in one molecule, and the balance of water Etching liquid composition comprising. The etchant composition of claim 1, wherein the phosphate salt compound is at least one selected from salts in which one to three hydrogens are substituted with an alkali metal or an alkaline earth metal in phosphoric acid. The etchant composition according to claim 2, wherein the phosphate salt is at least one selected from sodium dihydrogen phosphate and potassium dihydrogen phosphate. The method of claim 1, wherein the compound having an amino group and a carboxylic acid group in the molecule is alanine (alanine series, aminobutyric acid series, glutamic acid (glutamic acid), glycine (glycine) series, iminodiacetic acid), nitrilotriacetic acid series and sarcosine-based compounds, characterized in that the etchant composition characterized in that at least one selected from the group. The etchant composition of claim 1, wherein the etchant composition further comprises one or more of an etchant, a surfactant, a metal ion sequestrant, a corrosion inhibitor, and a pH regulator. The etchant composition according to any one of claims 1 to 5, wherein the etchant composition is capable of collectively etching a single film made of copper or a copper alloy and multiple films of at least two layers made of the metals.

Images