TWI495762B - Etchant composition and etching method - Google Patents

Description

Etching liquid composition and etching method

This invention relates to an etchant composition, and more particularly to an etchant composition for etching a copper-containing metal layer.

The wiring materials for small and medium-sized liquid crystal displays are currently dominated by aluminum or aluminum alloys. With the development of large-sized panels, displays require lower RC delay, shorter charging time, and lower aperture ratio. Therefore, on the wiring material, copper and its alloys with high conductivity and electromigration resistance are sought.

The copper-containing wiring is formed by depositing a single layer or a plurality of layers of copper, such as a copper-containing single layer metal, copper/titanium, copper/nickel, copper/molybdenum, and copper/molybdenum nitride. The photoresist is used as a mask to determine the required circuit pattern, and then anisotropic etching is performed by wet etching.

The etching performance needs to meet the following requirements: (1) Good cross-sectional shape, and the taper of the copper-containing wiring profile needs to be a positive taper angle. (2) Less metal residue is etched. (3) The end of the copper-containing wiring is less than 1.2 um on one side of the critical dimension bias (CD bias). In addition, since the metal dissolves into the etching solution during the etching process, the etching liquid maintains the ability to perform etching. And stability must also be considered to extend the life of the etchant.

In order to improve the stability of the etching solution, a common solution is to add a chelating agent such as ethylenediaminetetraacetic acid (EDTA) and salts thereof to the etching solution. However, such chelating agents have the following disadvantages: (1) they are not decomposed by organisms, and are liable to cause excessive chemical oxygen demand (COD) or biochemical oxygen demand (BOD) in the wastewater. (2) The chelation constant is too large, which makes it difficult to coagulate and precipitate metal ions during the treatment of the back-end wastewater. (3) When the concentration of the metal in the etching solution is increased, the etching liquid cannot maintain its etching performance.

In view of this, how to further improve the composition of the etching solution, while maintaining the stability of the etching solution, can simultaneously reduce the damage to the environment and prolong the service life of the etching solution, which is the goal of the industry.

It is an object of the present invention to provide an etchant composition which provides excellent etch performance and maintains its etch performance at high metal concentrations with a long lifetime.

Another object of the present invention is to provide an etchant composition which is more disposable and more environmentally compliant.

One embodiment in accordance with an aspect of the present invention is to provide an etchant composition for etching a copper-containing metal layer. The etching solution composition comprises hydrogen peroxide, a proton source, an organic base compound and an amino acid compound or a salt thereof, wherein the proton source excludes the fluorine-containing acid, and the organic base compound has a chain having at least one nitrogen atom and at least one carbon atom. a compound, and the pH of the organic base compound is greater than 8, and the amino acid compound is a monoamine carboxylic acid, a monoamine carboxylic acid The acid system contains only one nitrogen atom and a compound having at least one -COOH.

According to the aforementioned etching liquid composition, the proton source may be an acid having a pKa of less than 6. For example, the proton source can be acetic acid, glycolic acid, malic acid, lactic acid, succinic acid, malonic acid, gluconic acid, nitric acid, sulfuric acid or phosphoric acid.

According to the aforementioned etching liquid composition, the organic base compound may have at least one nitrogen atom and a chain compound having 2 to 8 carbon atoms. For example, the organic base compound may be triethanolamine, isopropanolamine, diglycolamine, isobutanolamine, propylenediamine, diethylaminopropylamine or dimethylaminopropylamine.

According to the foregoing etching liquid composition, the monoamine carboxylic acid may be triacetic acid ammonia, aspartic acid, glycine, iminodiacetic acid, N,N-dihydroxyethylglycine, N-methylimino Acetic acid, N-ethyliminodiacetic acid or N-(2-hydroxyethyl)iminodiacetic acid (HIDA/EA).

According to the foregoing etching liquid composition, the etching liquid composition may include 5 to 9 weight percent hydrogen peroxide, 5 to 20 weight percent of proton source, and 6 weight percent based on the etching liquid composition of 100% by weight. Up to 20% by weight of the organic base compound and 2% by weight to 10% by weight of the amino acid compound or a salt thereof. More preferably, the etchant composition may comprise from 5 weight percent to 9 weight percent hydrogen peroxide, from 5 weight percent to 20 weight percent proton source, from 6 weight percent to 13 weight percent, based on the etchant composition being 100 weight percent. The organic base compound and 2% by weight to 10% by weight of the amino acid compound or a salt thereof. The etchant composition may further comprise from 30% by weight to 82% by weight of water. In addition, etching The pH of the liquid composition is from 3 to 6.

One embodiment in accordance with another aspect of the present invention is to provide an etching method comprising etching a copper-containing metal layer using the etchant composition described above.

Fig. 1A is a scanning electron microscope (SEM) image showing a cross section of a copper-containing metal layer obtained by etching a copper-containing metal layer at the initial stage of etching in accordance with the etching liquid composition of Example 1 of the present invention.

Fig. 1B is an SEM image showing a cross section of a copper-containing metal layer obtained by etching an copper-containing metal layer in the late etching stage in accordance with the etching liquid composition of Example 1 of the present invention.

Fig. 2A is an SEM image showing a cross section of a copper-containing metal layer obtained by etching a copper-containing metal layer at the initial stage of etching in accordance with the etching liquid composition of Example 2 of the present invention.

Fig. 2B is an SEM image showing a cross section of the copper-containing metal layer obtained by etching the copper-containing metal layer at the later stage of etching in accordance with the etching liquid composition of Example 2 of the present invention.

Fig. 3A is an SEM image showing a cross section of a copper-containing metal layer obtained by etching a copper-containing metal layer at the initial stage of etching in accordance with the etching liquid composition of Example 3 of the present invention.

Fig. 3B is an SEM image showing a cross section of the copper-containing metal layer obtained by etching the copper-containing metal layer in the late etching stage in accordance with the etching liquid composition of Example 3 of the present invention.

Fig. 4A is a SEM image showing a cross section of a copper-containing metal layer obtained by etching a copper-containing metal layer at the initial stage of etching in accordance with the etching liquid composition of Example 4 of the present invention.

Fig. 4B is a SEM image showing a cross section of the copper-containing metal layer obtained by etching the copper-containing metal layer in the late etching stage in accordance with the etching liquid composition of Example 4 of the present invention.

Fig. 5A is an SEM image showing a cross section of a copper-containing metal layer obtained by etching a copper-containing metal layer at the initial stage of etching in accordance with the etching liquid composition of Example 5 of the present invention.

Fig. 5B is an SEM image showing a cross section of the copper-containing metal layer obtained by etching the copper-containing metal layer in the late etching stage in accordance with the etching liquid composition of Example 5 of the present invention.

Fig. 6A is an SEM image showing a cross section of a copper-containing metal layer obtained by etching a copper-containing metal layer at the initial stage of etching in accordance with the etching liquid composition of Example 6 of the present invention.

Fig. 6B is an SEM image showing a cross section of the copper-containing metal layer obtained by etching the copper-containing metal layer in the late etching stage in accordance with the etching liquid composition of Example 6 of the present invention.

Fig. 7A is an SEM image showing a cross section of a copper-containing metal layer obtained by etching a copper-containing metal layer at the initial stage of etching in accordance with the etching liquid composition of Example 7 of the present invention.

Fig. 7B is an SEM image showing a cross section of the copper-containing metal layer obtained by etching the copper-containing metal layer at the later stage of etching in accordance with the etching liquid composition of Example 7 of the present invention.

Fig. 8A is a SEM image showing a cross section of the copper-containing metal layer obtained by etching the copper-containing metal layer at the initial stage of etching of the etching liquid composition of Comparative Example 1'.

Fig. 8B is a SEM image showing a cross section of the copper-containing metal layer obtained by etching the copper-containing metal layer in the etching liquid composition of Comparative Example 1' at the later stage of etching.

Fig. 9A is a SEM image showing a cross section of the copper-containing metal layer obtained by etching the copper-containing metal layer at the initial stage of etching of the etching liquid composition of Comparative Example 2'.

Fig. 9B is a SEM image showing a cross section of the copper-containing metal layer obtained by etching the copper-containing metal layer in the etching liquid composition of Comparative Example 2' at the later stage of etching.

Fig. 10A is a SEM image showing a cross section of the copper-containing metal layer obtained by etching the copper-containing metal layer at the initial stage of etching of the etching liquid composition of Comparative Example 3'.

Fig. 10B is a SEM image showing a cross section of the copper-containing metal layer obtained by etching the copper-containing metal layer in the etching liquid composition of Comparative Example 3' at the later stage of etching.

Fig. 11 is a SEM image showing a cross section of the copper-containing metal layer obtained by etching the copper-containing metal layer at the initial stage of etching of the etching liquid composition of Comparative Example 4'.

<etching liquid composition>

An etchant composition for etching a copper-containing metal layer, specifically, for etching a copper-containing single-layer metal, copper/titanium, copper/nickel, copper/molybdenum, copper/molybdenum nitride, molybdenum/copper/ Multilayer metal layers such as molybdenum nitride, molybdenum nitride/copper/molybdenum nitride, and molybdenum nitride/copper/molybdenum.

The etching solution composition comprises hydrogen peroxide, a proton source, an organic base compound and an amino acid compound or a salt thereof, wherein the hydrogen peroxide and the proton source are used to provide an etching ability to the copper-containing metal layer, an organic alkali compound, The amino acid compound and its salt are used to enhance the stability of the etching liquid composition, to make the cross-sectional shape less prone to chamfering, and to maintain the etching performance of the etching liquid composition at a high metal ion concentration.

The pH of the etchant composition is from 3 to 6.

The hydrogen peroxide may be contained in an amount of from 5 to 9 weight percent based on the etching liquid composition of 100% by weight. When the content of hydrogen peroxide is less than 5 weight percent, the desired etching ability cannot be provided. When the content of hydrogen peroxide is more than 9 weight percent, the etching rate is lowered.

The proton source excludes the fluorine-containing acid, thereby avoiding etching of the germanium-containing layer, such as a glass substrate, a tantalum nitride layer or a hafnium oxide layer. The fluorine-containing acid refers to an acid containing a dissociable fluoride ion and/or a non-dissociable fluorine atom, and the fluorine-containing acid may be, but not limited to, hydrofluoric acid. The proton source can be an acid having a pKa of less than 6. example For example, the proton source may be acetic acid, glycolic acid, malic acid, lactic acid, succinic acid, malonic acid, gluconic acid, nitric acid, sulfuric acid or phosphoric acid, and the above-mentioned acids may be used singly or in combination of two or more. In other words, the proton source may be used alone or in combination of two or more.

The proton source may be included in an amount of from 5 to 20% by weight based on the etchant composition being 100% by weight. When the content of the proton source is less than 5% by weight, etching may not be possible, or, although etching may be performed, the etching rate at the later stage of etching may be lowered, and a preferable sectional shape may not be obtained, that is, the etching life may be short. When the content of the proton source is more than 20% by weight, the etching rate is too high, which will cause the CD bias to be excessive.

The above organic base compound is a chain compound having at least one nitrogen atom and at least one carbon atom, that is, the organic base compound excludes the azole compound, and the pH of the organic base compound is more than 8. Further, the organic base compound may be a chain compound having at least one nitrogen atom and having 2 to 8 carbon atoms. For example, the organic base compound may be triethanolamine, isopropanolamine, diglycolamine, isobutanolamine, propylenediamine, diethylaminopropylamine or dimethylaminopropylamine. Further, the aforementioned compounds may be used singly or in combination of two or more. In other words, the organic base compound may be used alone or in combination of two or more.

The content of the organic base compound may be from 6 to 20% by weight based on 100% by weight of the etching liquid composition. When the content of the organic alkali compound is less than 6% by weight, the buffering ability of the etching liquid composition is lowered, which leads to a failure in obtaining a preferable sectional shape at the late etching and an excessive CD bias, and at the same time, affecting etching uniformity or chamfering. when When the content of the organic base compound is more than 20% by weight, the etching rate is lowered. Preferably, the organic base compound may be included in an amount of from 6 to 13 weight percent.

The aforementioned amino acid compound is a monoamine carboxylic acid, and the monoamine carboxylic acid contains only one nitrogen atom and a compound having at least one -COOH. The aforementioned monoamine carboxylic acid may be nitrilotriacetic acid (NTA), aspartic acid, glycine, iminodiacetic acid, N,N-dihydroxy B. N,N-bis(2-hydroxyethyl)glycine, N-Methyliminodiacetic acid, N-Ethyliminodiacetic acid or hydroxyethyl N-(2-hydroxyethyl)iminodiacetic acid, HIDA/EA). Further, the aforementioned compounds may be used singly or in combination of two or more. In other words, the amino acid compound or a salt thereof may be used alone or in combination of two or more.

The content of the amino acid compound or a salt thereof may be from 2% by weight to 10% by weight based on 100% by weight of the etching liquid composition. When the content of the amino acid compound or a salt thereof is less than 2% by weight, the etching rate cannot be maintained at the later stage of etching, thereby lowering the production efficiency, and further, it is difficult to maintain the stability of hydrogen peroxide. When the content of the amino acid compound or a salt thereof is more than 10% by weight, the activity of hydrogen peroxide is lowered to affect the oxidizing ability of the etching liquid composition.

The etchant composition optionally includes at least one additive, such as a hydrogen peroxide stabilizer or an alcohol, to enhance its etch performance, with respect to being useful The additive for etching the copper-containing metal layer is conventional and will not be described herein.

The etchant composition may further comprise water, wherein the amount of water is from 30% by weight to 82% by weight of water. Specifically, the etching liquid composition uses water as a solvent, and the water may be, but not limited to, distilled water or deionized water, and deionized water is preferred. Further, the content of water varies depending on the sum of the contents of other components in the etching liquid composition, and in the presence of other components, water is added so that the content of the etching liquid composition is 100% by weight, in other words, hydrogen peroxide, The sum of the proton source, the organic base compound, the amino acid compound or a salt thereof, the additive, and water is 100% by weight.

The above "high metal ion concentration" means a metal concentration of more than 6000 ppm. The term "late etching" refers to a period in which the etching liquid composition is used after etching (usually after multiple etching) in which the metal concentration is greater than 6000 ppm.

<etching method>

An etching method comprising etching a copper-containing metal layer using the etchant composition described above.

According to the above embodiment, specific examples and comparative examples will be described in detail below.

<Examples and Comparative Examples>

First, the etching liquid compositions of Examples 1 to 7 and the etching liquid compositions of Comparative Examples 1' to 4' were prepared. The pH values of the etching liquid compositions of Examples 1 to 7 are shown in Table 1, and the compositions of the etching liquid compositions of Examples 1 to 7 are shown in Table 2, and the etching liquid compositions of Comparative Examples 1' to 4' were used. The pH values are shown in Table 3, and the compositions of the etching liquid compositions of Comparative Examples 1' to 4' are shown in Table 4.

Next, a 5000 Å copper layer and a 180 Å molybdenum layer are deposited on the glass substrate to form a copper/molybdenum double layer metal layer, a photoresist is coated on the glass substrate on which the metal layer is deposited, and exposed and developed to form a reticle. Further, the etching liquid compositions of Examples 1 to 7 and the etching liquid compositions of Comparative Examples 1' to 4' were etched at 30 to 35 ° C, respectively. The etching performance is shown in Table 5 below and Table 6 below.

In Tables 5 and 6, the metal just etching time refers to the time taken from the start of etching to the first exposure of the glass substrate to the composition of the etching liquid. The total etching time refers to the time taken from the start of etching to the end of etching.

Etching, CD bias, and chamfering. The glass substrate on which the metal layer was deposited was observed by SEM through the etching liquid compositions of Examples 1 to 7 and the etching liquid compositions of Comparative Examples 1' to 4', respectively. Sectional view. Wherein, the etching angle is measured by cutting the glass substrate on which the metal layer is deposited, and measuring the angle of the cross section of the metal layer of the obtained cross section; the chamfering is measuring the angle between the bottom of the cross section of the metal layer and the glass substrate. If it is greater than 90 degrees, it is judged as chamfering and evaluated as "X". If no chamfering occurs, it is evaluated as "○"; CD bias is used to measure the horizontal distance from the end of the photoresist to the bottom end of the metal layer.

The initial etching refers to the first etching, that is, the etching liquid composition has a copper ion content of about 0 ppm before etching. Post-etching refers to the etchant composition having a copper ion content of about 10,000 ppm after etching (usually after multiple etchings).

The etch angle variation is the etch angle of the initial etch minus the post etch The etch angle, the etch angle variation is preferably less than 20 degrees.

The CD bias variation is the CD bias of the initial etch minus the CD bias of the post-etch, and the CD bias variation is preferably less than 0.2 microns.

If the etching angle variation is less than 20 degrees, the CD bias variation is less than 0.2 μm, and no chamfering occurs, the etching performance retention ability after etching a plurality of times is evaluated as “○”.

Please refer to Table 5, Table 6 and Figures 1A to 11 below. Table 5 is the etching performance of Examples 1-7, and Figures 1A to 7B are the etching liquids according to Embodiments 1~7 of the present invention, respectively. SEM image of a cross section of a copper-containing metal layer obtained by etching a copper-containing metal layer at the initial stage of etching and at the end of etching. Table 6 is the etching performance of Comparative Example 1'~4', and FIG. 8A to FIG. 11 are the copper-containing copper composition obtained by etching the copper-containing metal layer in the initial stage of etching and the etching stage of the etching liquid composition of Comparative Example 1'~4', respectively. SEM image of the metal layer profile.

It can be seen from Table 5 and Figures 1A to 7B that the etching of the copper-containing metal layer using the etching liquid compositions according to Embodiments 1 to 7 of the present invention does not cause chamfering, and the etching angle variation is much less than 20 degrees, CD The bias is less than 0.2 μm, and it is apparent that the etching liquid composition according to the present invention has an excellent etching performance after etching a plurality of times. In other words, the etching liquid composition of the present invention can maintain the etching performance at a high metal ion concentration, and has Long service life. Further, in the etching liquid composition of the present invention, the ability of the amino acid compound to chelate with copper ions is appropriate, and compared with EDTA, it is less likely to cause difficulty in the treatment of the terminal wastewater. From Table 6 and Figures 8A through 11, it can be seen that Comparative Example 1' uses an inorganic base without using an organic base compound, and the etching angle variation is as high as 43.51 degrees, and the CD bias variation is as high as 3 μm, indicating etching after etching a plurality of times. Poor performance performance. Comparative Example 2' used an inorganic base without using an organic base, which was chamfered at the initial etching, and the CD bias variation was 0.62 μm (greater than 0.2), indicating that the etching performance after the etching was performed many times was poor. Comparative Example 3' used an inorganic base and an azole compound (imidazole) without using an organic base compound, which was chamfered in both initial etching and post-etching, and the CD bias variation was 0.22 μm (greater than 0.2), indicating that it was etched multiple times. Rear The etch performance is poorly maintained. Comparative Example 4' did not use an amino acid compound, which was chamfered in the initial etching, and was not etched due to insufficient etching ability in the later etching, and it was found that the etching performance after the etching was not performed was poor. As is apparent from the results of Comparative Examples 1' to 4', if the organic alkali compound is absent in the composition of the etching liquid of the present invention, chamfering is liable to occur, and the etching performance after etching is not good, that is, it is difficult to extend etching. The service life of the liquid composition. If the etching liquid composition of the present invention does not use an amino acid compound, chamfering tends to occur, and etching cannot be performed after a plurality of etchings, resulting in a significantly shorter service life of the etching liquid composition. Therefore, in the etching liquid composition of the present invention, hydrogen peroxide, a proton source, an organic base compound and an amino acid compound need to be used at the same time to achieve good etching performance, and the etching performance can be maintained even at a high metal ion concentration. And has a long service life.

While the present invention has been disclosed in the above embodiments, it is not intended to limit the invention, and the invention may be modified and modified in various ways without departing from the spirit and scope of the invention. The scope is subject to the definition of the scope of the patent application.

Claims (12)

An etchant composition for etching a copper-containing metal layer, the etchant composition comprising: hydrogen peroxide; a proton source excluding a fluorine-containing acid; and an organic base compound having at least one nitrogen a chain compound of an atom and at least one carbon atom, wherein the pH of the organic base compound is greater than 8; and an amino acid compound or a salt thereof, the amino acid compound being a monoamine carboxylic acid, the monoamine carboxylic acid containing only a nitrogen atom and a compound having at least one -COOH. The etchant composition of claim 1, wherein the proton source is an acid having a pKa of less than 6. The etchant composition of claim 2, wherein the proton source is acetic acid, glycolic acid, malic acid, lactic acid, succinic acid, malonic acid, gluconic acid, nitric acid, sulfuric acid or phosphoric acid. The etching liquid composition according to claim 1, wherein the organic base compound has at least one nitrogen atom and a chain compound having 2 to 8 carbon atoms. An etchant composition as claimed in claim 4, wherein the organic alkalization The compound is triethanolamine, isopropanolamine, diglycolamine, isobutanolamine, propylenediamine, diethylaminopropylamine or dimethylaminopropylamine. The etching solution composition according to claim 1, wherein the monoamine carboxylic acid is triacetoxy ammonia, aspartic acid, glycine, iminodiacetic acid, N,N-dihydroxyethylglycine, N- Methyliminodiacetic acid, N-ethyliminodiacetic acid or N-(2-hydroxyethyl)iminodiacetic acid (HIDA/EA). The etchant composition according to any one of claims 1 to 6, wherein the etchant composition comprises: 5 to 9 wt% of the hydrogen peroxide based on the etchant composition being 100 wt% 5 parts by weight to 20% by weight of the proton source; 6 parts by weight to 20% by weight of the organic base compound; and 2% by weight to 10% by weight of the amino acid compound or a salt thereof. The etchant composition of claim 7, further comprising: 30% by weight to 82% by weight of water. The etchant composition according to any one of claims 1 to 6, wherein the etchant composition has a pH of 3 to 6. The etching liquid composition according to any one of claims 1 to 6, wherein the etching liquid composition comprises: 5 to 9 weight percent of the hydrogen peroxide based on the etching liquid composition: 100% by weight 5 parts by weight to 20% by weight of the proton source; 6 parts by weight to 13% by weight of the organic base compound; and 2% by weight to 10% by weight of the amino acid compound or a salt thereof. An etching method comprising: etching the copper-containing metal layer using the etching liquid composition according to any one of claims 1 to 6. An etching method comprising: etching the copper-containing metal layer using an etchant composition as recited in claim 7.