KR20250124614A - Two-liquid type titanium etchant composition - Google Patents

Abstract

The present invention relates to a two-component titanium etchant composition, and more specifically, to a two-component titanium etchant composition comprising a first solution containing an alkaline compound and a second solution containing hydrogen peroxide, wherein the first solution comprises 20 to 30 wt% of potassium hydroxide, 1 to 10 wt% of phosphoric acid, 0.1 to 1 wt% of a metal chelator, 0.02 to 0.1 wt% of a hydrogen peroxide radical scavenger, and a balance of water.

Description

Two-liquid type titanium etchant composition

The present invention relates to a two-component titanium etchant composition, and more specifically, to a two-component titanium etchant composition comprising a first solution containing an alkaline compound and a second solution containing hydrogen peroxide, wherein the first solution comprises 20 to 30 wt% of potassium hydroxide, 1 to 10 wt% of phosphoric acid, 0.1 to 1 wt% of a metal chelator, 0.02 to 0.1 wt% of a hydrogen peroxide radical scavenger, and a balance of water.

In general, the titanium layer deposited by sputtering in the Through Silicon Via, Re-Distributed Layer, and CPB (Cu Pillar Bump) processes forms a stable seed layer for the copper layer, and is used as an auxiliary layer that serves as a lead line in plating to form a pattern or bumper in the future.

The titanium and copper layers in the unnecessary space area are electrically separated through a predetermined etching process, and applications are mounted here or an insulator is filled to form a single substrate layer. At this time, wet etching is used as a method to remove the sputtered titanium layer, and the etchant used for this purpose is mainly a mixture of an alkaline compound and hydrogen peroxide.

In these etchants, hydrogen peroxide oxidizes titanium to form a titanium oxide film, which is then dissolved and removed by the action of hydroxyl groups contained in the alkaline compound. However, when hydrogen peroxide and an alkaline compound are mixed, the hydrogen peroxide decomposes over time, generating radicals. Therefore, conventional titanium etchants are provided in the form of a two-component composition in which the hydrogen peroxide and the alkaline compound are separated, and the user mixes them for use.

Furthermore, conventional etchants only use metal chelators as stabilizers to improve the bath life of hydrogen peroxide, but radical scavengers, which are more effective stabilizers, are not used. This is because the peroxidizing properties of hydrogen peroxide reduce the content of radical scavengers in the product, which ultimately shortens the shelf life.

Patent No. 10-1709925 (February 20, 2017) Patent No. 10-2291351 (August 12, 2021) Patent No. 10-2527728 (April 26, 2023)

Conventional titanium etchants have the following challenges:

First, the mixture of hydrogen peroxide and alkaline compounds rapidly generates radicals as hydrogen peroxide decomposes at pH 8, and this decomposition of hydrogen peroxide reduces the titanium etching performance, requiring frequent chemical replacement and resulting in the generation of a large amount of waste liquid.

Second, when a radical scavenger is mixed with hydrogen peroxide, the function of the radical scavenger is significantly reduced due to the peroxidizing property of hydrogen peroxide.

Third, although the decomposition of hydrogen peroxide by metal ions in a mixture of hydrogen peroxide and an alkaline compound can be prevented to some extent by using a metal chelator, it is insufficient in preventing further decomposition of hydrogen peroxide because it cannot suppress the generation of radicals in hydrogen peroxide.

Accordingly, the problem to be solved by the present invention is a two-component titanium etching composition comprising a first liquid containing an alkaline compound and a second liquid containing hydrogen peroxide.

The present invention provides a two-component titanium etchant composition capable of extending the shelf life by inhibiting degeneration in the product state by mixing a metal chelator and a radical scavenger into an alkaline compound.

In addition, the problem to be solved by the present invention is to provide a two-component titanium etchant composition capable of extending the bath life of the etchant by controlling the metal ions generated when etching a titanium layer by mixing a first solution containing an alkaline compound and a second solution containing hydrogen peroxide with a metal chelator and suppressing radicals, which are a decomposition state of hydrogen peroxide, with a scavenger.

A two-component titanium etching composition according to the present invention comprises a first component containing an alkaline compound and a second component containing hydrogen peroxide, wherein the first component comprises 20 to 30 wt% of potassium hydroxide, 1 to 10 wt% of phosphoric acid, 0.1 to 1 wt% of a metal chelator, 0.02 to 0.1 wt% of a hydrogen peroxide radical scavenger, and a balance of water.

The above second solution is composed of a hydrogen peroxide aqueous solution having a concentration of 20 to 35%, and the amount of the second solution used is characterized by being 10 to 30 times that of the first solution.

The two-component titanium etchant composition according to the present invention has the effect of extending the shelf life by suppressing degeneration in the product state, since a metal chelator and a radical scavenger are mixed in an alkaline compound.

In addition, the metal ions generated when etching the titanium layer are controlled by the metal chelator, and the radicals, which are a decomposition state of hydrogen peroxide, are suppressed by the scavenger, which has the effect of extending the bath life of the etchant.

Hereinafter, the present invention will be described in detail using the attached drawings. However, since the attached drawings illustrate preferred embodiments of the present invention, the scope of the present invention is not limited by these embodiments.

In addition, even if it is a configuration that is absolutely necessary for carrying out the present invention, a detailed description is omitted for matters that are introduced in the prior art or that can be easily carried out by a person skilled in the art from known technology.

And to ‘include’ a component means that in addition to the specified components, other components can be included as needed.

The titanium etching composition according to the present invention is composed of a first liquid containing an alkaline compound and a second liquid containing hydrogen peroxide.

And the first liquid contains potassium hydroxide (KOH) as an alkaline compound, phosphoric acid (H ₃ PO ₄ ) as an inorganic acid, a metal chelator, a hydrogen peroxide radical scavenger, and the remainder water.

The above alkaline compound, i.e. potassium hydroxide, has the function of dissolving the titanium oxide film created by the reaction of hydrogen peroxide and titanium (Ti). As the concentration of the alkaline compound increases, the pH increases and the etching speed increases, but when mixed with the second liquid, it promotes the decomposition of hydrogen peroxide, which is not desirable.

Therefore, the content of potassium hydroxide is preferably 20 to 30 wt% with respect to the first solution in order to minimize the change in the ratio of hydrogen peroxide when the first solution and the second solution are mixed.

Next, the inorganic acid, i.e. phosphoric acid, acts as a buffer to suppress rapid pH fluctuations according to the amount of potassium hydroxide added, and its content is preferably 1 to 10 wt% with respect to the first solution.

In general, it is desirable for the etchant to maintain a pH range of 8 to 10 in order to have a stable etching rate for the titanium oxide film. However, if the content of inorganic acid is less than 1 wt% or, conversely, more than 10 wt%, the pH of the etchant will fall outside this range, which is undesirable.

A metal chelator captures titanium (Ti) ions generated during the process of etching a titanium layer and suppresses the decomposition of hydrogen peroxide by titanium ions, and its content is comprised at 0.1 to 1 wt% with respect to the first solution.

If the content of the above metal chelator is less than 0.1 wt%, it cannot function effectively as a chelator, and conversely, if it exceeds 1 wt%, it is not preferable because a change in the etching speed of the titanium layer occurs.

Any one or more of the above ethylenediamine tetra(methylene phosphonic acid) (CAS 1429-50-1), 1,2-diamino propane-N,N,N′,N′-tetrakis(methylphosphonic acid) (CAS 28698-31-9), diethylene triamine penta(methylene phosphonic acid) (CAS 15827-60-8), and trans-1,2-diamino cyclohexane-N,N,N′,N′-tetra acetic acid monohydrate (CAS 125572-95-4) may be used.

Lastly, the radical scavenger removes hydrogen peroxide radicals generated when etching the titanium layer, thereby inhibiting the decomposition of hydrogen peroxide by hydrogen peroxide radicals.

The content of the radical scavenger is preferably 0.02 to 0.1 wt%. If the content is less than 0.02 wt%, the scavenger is not effective, and if it exceeds 0.1 wt%, the solubility is insufficient, which is not preferable.

As the above radical scavenger, one or more of phenyl urea and 1,3-diphenyl urea can be used.

The first solution comprises potassium hydroxide, phosphoric acid, a metal chelator and a hydrogen peroxide radical scavenger, with the remainder being water.

Meanwhile, the second solution is composed of a hydrogen peroxide aqueous solution with a concentration of 20-35%. At this time, if the concentration of the hydrogen peroxide aqueous solution is less than 20%, there is a problem of a low etching rate for the titanium layer, and if it exceeds 35%, there is a problem of an excessively high etching rate for the titanium layer. The preferred concentration of the hydrogen peroxide aqueous solution constituting the second solution is 31%.

The titanium etching composition according to the present invention is used by mixing a first solution and a second solution. At this time, the amount of the second solution used may be 10 to 30 times that of the first solution. The preferred mixing ratio of the first solution and the second solution is 5:95 wt%.

Hereinafter, preferred embodiments of the present invention are presented.

[Example]

As an example of the etchant composition of the present invention, a first solution and a second solution were prepared according to the components and content ratios shown in [Table 1] below. The first solution of each example (total 100 wt%) includes the remaining amount of water in addition to the four components.

Example Liquid 1 (unit: weight%) Second liquid KOH Phosphoric acid chelator Scavenger hydrogen peroxide 1 20% 1% DTPPA 0.2% 1,3-diphenyl urea 0.02% 31% 2 20% 2% DPTPA 0.2% Phenyl urea 0.02% 31% 3 23% 2% EDTMP 0.4% 1,3-diphenyl urea 0.03% 31% 4 23% 4% DPTPA 0.4% Phenyl urea 0.03% 31% 5 23% 5% DTPPA 0.4% Phenyl urea 0.03% 31% 6 25% 3% CyDTA 0.4% 1,3-diphenyl urea 0.05% 31% 7 25% 5% DPTPA 0.6% Phenyl urea 0.05% 31% 8 25% 5% DTPPA 0.6% 1,3-diphenyl urea 0.05% 31% 9 27% 5% CyDTA 0.8% 1,3-diphenyl urea 0.07% 31% 10 27% 7% EDTMP 0.8% Phenyl urea 0.07% 31% 11 30% 7% CyDTA 1% 1,3-diphenyl urea 0.1% 31% 12 30% 10% EDTMP 1% Phenyl urea 0.1% 31%

The meanings of the abbreviations used as chelators in the above [Table 1] are as follows.

- DTPPA; Diethylene triamine penta(methylene phosphonic acid)

- DPTPA; 1,2-diaminopropane-N,N,N′,N′-tetrakis(methylphosphonic acid)

- EDTMP; Ethylenediamine tetra(methylene phosphonic acid)

- CyDTA; trans-1,2-diaminocyclohexane-N,N,N',N'-tetraacetic acid monohydrate

[ Comparative example ]

As comparative examples for the above embodiment, the first and second solutions were prepared according to the components and content ratios as shown in [Table 2] below. The first solution of each comparative example (total 100 wt%) is lacking at least one of the four essential components (KOH, phosphoric acid, chelator, scavenger) of the present invention, or the content of each component is outside the scope of the claims of the present invention, and includes a residual amount of water.

Comparative example Liquid 1 (unit: weight%) Second liquid KOH Phosphoric acid chelator Scavenger hydrogen peroxide 1 5% 0.5% DTPPA 0.2% - 31% 2 10% 1% DPTPA 0.4% Phenyl urea 0.03% 31% 3 15% 2% - 1,3-diphenyl urea 0.05% 31% 4 15% 4% CyDTA 0.2% 1,3-diphenyl urea 0.003% 31% 5 20% 0.5% EDTMP 0.4% Phenyl urea 0.005% 31% 6 20% 1% - - 31% 7 23% 2% DPTPA 0.05% Phenyl urea 0.005% 31% 8 23% 4% DTPPA 0.1% 1,3-diphenyl urea 0.005% 31% 9 23% 6% CyDTA 0.5% - 31% 10 25% 4% EDTMP 0.5% - 31% 11 25% 6% - - 31% 12 27% 4% DPTPA 0.6% - 31% 13 27% 6% - Phenyl urea 0.01% 31% 14 35% 10% EDTMP 0.8% 1,3-diphenyl urea 0.05% 31% 15 40% 12% - Phenyl urea 0.15% 31% 16 40 15 CyDTA 1% 1,3-diphenyl urea 0.2% 31%

[Performance Test]

1) Evaluation items

A titanium etchant composition was prepared by mixing 5 wt% of the first liquid and 95 wt% of the second liquid prepared according to the above examples and comparative examples, and the Ti etching rate, circuit bottom undercut level, and hydrogen peroxide decomposition property of the etchant composition were evaluated, and the results are listed in [Table 3] and [Table 4] below.

Example Ti etching rate Circuit undercut level Hydrogen peroxide decomposition 1 ◎ ○ ◎ 2 ○ ◎ ◎ 3 ◎ ○ ◎ 4 ○ ◎ ◎ 5 ○ ◎ ◎ 6 ◎ ○ ◎ 7 ○ ◎ ◎ 8 ○ ○ ◎ 9 ◎ ○ ◎ 10 ○ ○ ◎ 11 ○ ○ ◎ 12 ○ ○ ◎

Comparative example Ti etching rate Circuit undercut level Hydrogen peroxide decomposition 1 Ⅹ Ⅹ Ⅹ 2 Ⅹ Ⅹ ◎ 3 Ⅹ ○ ◎ 4 Ⅹ △ Ⅹ 5 ◎ △ Ⅹ 6 ◎ ○ Ⅹ 7 ◎ ○ △ 8 ○ ○ △ 9 △ △ Ⅹ 10 ○ ◎ Ⅹ 11 △ ○ Ⅹ 12 ◎ ○ Ⅹ 13 ○ ○ △ 14 ◎ △ △ 15 ◎ Ⅹ △ 16 ○ Ⅹ Ⅹ

2) Test method

First, for the Ti etching rate test, a substrate coated with a 1,000 Å thick Ti thin film was placed in the etchant compositions of the examples and comparative examples, and dipped and swung at a temperature of 30°C for 30 seconds or 1 minute, and then the change in thickness of the Ti thin film was measured using an XRF analyzer. The same test was repeated three times and the average value was taken.

Next, the circuit lower undercut test was conducted in the same manner as the Ti etching rate test, but the undercut level was measured based on the EPD (end point detection) × 2 times for the fine pitch redistribution layer (RDL).

Finally, the hydrogen peroxide decomposition property was measured by adding Ti ions at a concentration of 0.1 g/L to the etchant compositions of the above examples and comparative examples, and measuring the change in the concentration of Ti ions after 24 hours at a temperature of 30°C.

3) Evaluation criteria

The evaluation criteria for the above evaluation items are as follows [Table 5].

Evaluation criteria Ti etching rate Circuit undercut level Hydrogen peroxide decomposition ◎ 1,000Å/min or more 200 nm or less 10% or less ○ 700Å/min or more 250 nm or less 15% or less △ 500Å/min or more 300 nm or less 30% or less Ⅹ Less than 500Å/min Over 300 nm Over 30%

4) Evaluation results

As shown in the above [Table 3] and [Table 4], the titanium etchant composition according to the present invention was confirmed to have relatively superior performance in all evaluation items compared to the etchant composition of the comparative example.

Claims (5)

A two-component titanium etching composition comprising a first liquid containing an alkaline compound and a second liquid containing hydrogen peroxide, wherein the first liquid comprises 20 to 30 wt% of potassium hydroxide, 1 to 10 wt% of phosphoric acid, 0.1 to 1 wt% of a metal chelator, 0.02 to 0.1 wt% of a hydrogen peroxide radical scavenger, and the remainder of water.
A two-component titanium etching composition characterized in that in the first paragraph, the second liquid is composed of a hydrogen peroxide aqueous solution having a concentration of 20 to 35%, and the amount of the second liquid used is 10 to 30 times that of the first liquid.
In the first paragraph, the metal chelator is characterized in that at least one of ethylene diamine tetra(methylene phosphonic acid), 1,2-diamino propane-N,N,N′,N′-tetrakis(methylphosphonic acid), diethylene triamine penta(methylene phosphonic acid), and trans-1,2-diamino cyclohexane-N,N,N′,N′-tetra acetic acid monohydrate is present.
A two-component titanium etchant composition, characterized in that in claim 1, the hydrogen peroxide radical scavenger is at least one of phenyl urea and 1,3-diphenyl urea.
A first solution comprising 20 to 30 wt% of potassium hydroxide, 1 to 10 wt% of phosphoric acid, 0.1 to 1 wt% of 1,2-diamino propane-N,N,N′,N′-tetrakis(methylphosphonic acid), 0.02 to 0.1 wt% of phenylurea, and the remainder of water;
A second solution comprising a hydrogen peroxide aqueous solution having a concentration of 25 to 35%;
A two-component titanium etching composition characterized in that the first and second liquids are mixed in a weight ratio of 5:95.