JP2002053984A - Etching liquid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an etching solution which achieves stabilization of hydrogen peroxide when etching titanium, tungsten or a titanium-tungsten alloy, is economical and has excellent operation stability. SOLUTION: 5-Amino-1H-tetrazole, 5-methyltetrazole and 3-amino-1H-
An etching solution for a semiconductor device having a metal film, comprising at least one selected from the group consisting of 1,2,4-triazole and an aqueous solution of hydrogen peroxide.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the manufacture of semiconductor devices, and more particularly to an etching solution for titanium, tungsten or a titanium-tungsten alloy.

[0002]

2. Description of the Related Art Metal layers of titanium, tungsten and titanium-tungsten alloy are generally used as barrier layers in electronic parts. Especially in semiconductor parts,
These barrier layers are used to prevent metal ions from diffusing into and contaminating the underlying semiconductor substrate. As an etchant for etching these barrier layers, an aqueous solution of hydrogen peroxide is used. Titanium and hydrogen peroxide react by etching to generate titanium oxide, and tungsten and hydrogen peroxide react to oxidize. Tungsten is produced.

However, in such an etching method, hydrogen peroxide used as an etchant releases oxygen itself and gradually decomposes, and when containing a metal, decomposition is accelerated. Furthermore, when the temperature of the etching solution is increased to improve the etching rate, the decomposition rate of hydrogen peroxide is also increased, which shortens the life of the etching solution and also controls the concentration of hydrogen peroxide in the etching solution. Very difficult. In order to solve such a problem, it is known to add a chelating agent such as ethylenediaminetetraacetic acid to improve the stability of the solution. However, even with this method, the stability of the solution is insufficient, and there is a risk that hydrogen peroxide may be rapidly decomposed when the processing temperature is increased to improve the etching rate.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems in the prior art, and to provide an economical and operationally stable etching method in which hydrogen peroxide in an etching solution is kept stable. To provide a liquid.

[0005]

Means for Solving the Problems The inventors of the present invention have made intensive studies to solve the above-mentioned problems, and as a result, by adding a specific azole to an aqueous solution of hydrogen peroxide, even if etching is continued, the excess in the solution is maintained. The inventors have found that the stability of hydrogen oxide is maintained, and have reached the present invention. That is, the present invention includes that at least one selected from the group consisting of 5-amino-1H-tetrazole, 5-methyltetrazole and 3-amino-1H-1,2,4-triazole and an aqueous hydrogen peroxide solution. The present invention relates to an etching solution for a semiconductor substrate having a characteristic metal film, or an etching method using the etching solution.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The etching solution of the present invention is an aqueous solution comprising hydrogen peroxide and specific azoles. The concentration of hydrogen peroxide is determined by the required etching rate, but is preferably 25 to 45% by weight. When the concentration of hydrogen peroxide is lower than 25% by weight, the dissolution rate is low, and the dissolving efficiency is deteriorated. When the concentration is higher than 45% by weight, there is a problem in safety.

As the azole, a compound having an azole group and a water-soluble substance is used. In particular, azoles selected from 5-amino-1H-tetrazole, 5-methyltetrazole and 3-amino-1H-1,2,4-triazole can be suitably used. The concentration of the azoles may be any as long as it can be dissolved in an aqueous hydrogen peroxide solution, but is preferably 0.005 to 0.5% by weight. If the amount of azoles is less than 0.005% by weight, a sufficient effect of stabilizing hydrogen peroxide cannot be obtained, and if the amount is more than 0.5% by weight, the effect does not change, and the economic efficiency is poor, which is not preferable.

[0008] A chelating agent may be added to the etching solution of the present invention. Examples of the chelating agent include ethylenediaminetetraacetic acid or diethylenetriaminepentaacetic acid, or an alkali metal salt or an ammonium salt thereof. The addition amount is preferably 0.005 to 0.5% by weight.

The processing temperature of the etching solution of the present invention is as follows:
The temperature is 30 to 60 ° C, preferably 40 to 50 ° C. If the treatment temperature is too low, a sufficient dissolving effect cannot be obtained. If the treatment temperature is too high, decomposition of hydrogen peroxide in the solution proceeds, which is not preferable.

[0010]

EXAMPLES Examples of the present invention will be described below, but the present invention is not limited to these examples.

Example 1 A wafer on which a titanium / tungsten film was sputtered was immersed in an etching solution with 1 liter of an aqueous solution containing 30% by weight of hydrogen peroxide and 0.01% by weight of 5-amino-1H-tetrazole. When the concentration became 30 mg / l and the tungsten concentration became 1200 mg / l, a part of the liquid was extracted and the concentration of hydrogen peroxide was measured. After keeping this solution at 50 ° C. for 24 hours, the concentration of hydrogen peroxide was measured again, and the residual ratio of hydrogen peroxide (%) was determined.

Example 2 The same procedure as in Example 1 was carried out except that the amount of 5-amino-1H-tetrazole was changed to 0.1% by weight.

Example 3 Example 1 except that the amount of 5-methyltetrazole was changed to 0.01% by weight instead of 5-amino-1H-tetrazole.
Was performed in the same manner as described above.

Example 4 The procedure of Example 1 was repeated, except that the amount of 5-methyltetrazole was changed to 0.1% by weight instead of 5-amino-1H-tetrazole.

Example 5 The same procedure as in Example 1 was carried out except that the amount of 3-amino-1H-1,2,4-triazole was changed to 0.01% by weight instead of 5-amino-1H-tetrazole.

EXAMPLE 6 Instead of 5-amino-1H-tetrazole, the amount of 3-amino-1H-1,2,4-triazole was changed to 0.1% by weight.
The procedure was performed in the same manner as in Example 1 except that

EXAMPLE 7 The amount of ethylenediaminetetraacetic acid / 4 sodium salt was adjusted to 0.0
It carried out similarly to Example 1 except having added 1 weight%.

Example 8 Example 8 was carried out in the same manner as in Example 1, except that 0.01% by weight of diethylenetriaminepentaacetic acid / 5 sodium salt was added.

COMPARATIVE EXAMPLE 1 A wafer on which a titanium / tungsten film was sputtered was immersed in an etching solution with 1 liter of an aqueous solution containing 30% by weight of hydrogen peroxide to obtain a titanium concentration of 30 mg / l and a tungsten concentration of 1200 mg / l. A part of the liquid was withdrawn by using to measure the concentration of hydrogen peroxide. After keeping this solution at 50 ° C. for 24 hours, the concentration of hydrogen peroxide was measured again, and the residual ratio of hydrogen peroxide (%) was determined.

Comparative Example 2 The same procedure as in Comparative Example 1 was carried out except that 0.01% by weight of ethylenediaminetetraacetic acid / 4 sodium salt was added.

Comparative Example 3 Diethylenetriaminepentaacetic acid / 5 sodium salt was added to 0.0
The operation was performed in the same manner as in Comparative Example 1 except that 1% by weight was added.

[0022]

[Table 1]

[0023]

According to the present invention, when etching titanium, tungsten or a titanium-tungsten alloy,
Stabilization of hydrogen peroxide can be achieved, and an etching solution that is economical and has excellent operation stability can be obtained.

Continued on the front page F term (reference) 4K057 WB08 WE25 WF01 WF10 WG02 WG03 5E339 BC01 BE17 5F043 AA26 BB18 DD07 EE22 EE23 GG10

Claims (3)

[Claims] (1) 5-amino-1H-tetrazole, 5-
Methyltetrazole and 3-amino-1H-1,2,2
An etching solution for a semiconductor device having a metal film, comprising at least one selected from the group consisting of 4-triazole and an aqueous solution of hydrogen peroxide. 2. The etching solution according to claim 1, wherein the metal film is titanium, tungsten or a titanium-tungsten alloy. 3. A semiconductor substrate having a metal film comprising at least one selected from the group consisting of 5-amino-1H-tetrazole, 5-methyltetrazole and 3-amino-1H-1,2,4-triazole and hydrogen peroxide An etching method for a semiconductor device, wherein the semiconductor device is treated with an etching solution containing an aqueous solution.