JPH0610161A - Etching solution composition for thin al-si film - Google Patents

Abstract

PURPOSE:To provide an etching soln. compsn. for a thin Al-Si film capable of etching an Al-Si electrode or wiring by an easy method without requiring expensive equipment. CONSTITUTION:This etching soln. compsn. is a mixture of hydrofluoric acid, nitric acid and water in 10:250:60 volume ratio and can etch a thin Al-Si film in a single etching process without using an expensive etching device. The etching of the thin Al-Si film is carried out in two stages up to now by separately etching Al and Si.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an Al-Si thin film etching solution composition used in the manufacture of semiconductor devices.

[0002]

2. Description of the Related Art Conventionally, Al-S has been used in the manufacturing process of semiconductor devices.
The etching for forming the i-electrode is performed by etching Al and removing the residue S.
It was performed by the two-step etching of the etching of i.
That is, the wet etching, the dry etching, and the method of using two kinds of gases in the dry etching are used, and both have a problem that an expensive dry etching apparatus is required.

The wet etching is performed using only a phosphoric acid solution or a mixed solution of phosphoric acid, nitric acid, acetic acid and water. When only the phosphoric acid solution is used, a large amount of hydrogen gas bubbles generated by the reaction between Al and phosphoric acid adhere to the Al-Si surface, leaving an etching residue. Therefore, etching is performed while removing the bubbles by a spray method, a pressure reduction method, or the like. A method is used. In the spray method, phosphoric acid solution is passed through a nozzle to
This is a method of spraying on the 1-Si surface. The depressurization method is a method of removing hydrogen gas generated by the reaction with Al using a vacuum pump.

When a mixed solution of phosphoric acid, nitric acid, acetic acid and water is used, since the viscosity of the mixed solution is lower than that of phosphoric acid alone, hydrogen gas generated by the reaction with Al easily escapes to the liquid surface, There is an advantage that etching can be performed by a simple method.

In the dry etching, a plasma etching apparatus or a reactive sputter etching apparatus is used to activate an etching gas (CF ₄ gas or a mixed gas of CF ₄ and O ₂ ) to react with Si and remove it. Is the way.

The above-mentioned conventional etching method will be described below with reference to the drawings. FIG. 3 illustrates an etching method using two-step etching including wet etching and dry etching. In this two-step etching method,
When Al—Si is etched by wet etching, Si residue 2 remains on the substrate 1 and its cross section has a shape as shown in FIG. In FIG. 3A, 3 is a patterned Al-Si thin film, and 4 is a resist formed on this Al-Si thin film 3. So the remaining S
When i residue 2 is removed by dry etching, as shown in FIG.
The shape is as shown in (B), and finally Al-Si
The resist 4 on the thin film 3 is removed and the structure shown in FIG.

In the dry etching, a reactive sputter etching apparatus is used, and CCl ₄ gas is used to produce Al-S.
When the i thin film is etched, as shown in FIG.
Residue 2 remains. Then, using a CF ₄ gas system, Si residue 2
Is removed by etching, as shown in FIG.

However, with either method, Al--S
An expensive dry etching apparatus is required to etch the i thin film.

[0009]

SUMMARY OF THE INVENTION The present invention is intended to solve such a problem. An Al-Si thin film can be used for etching Al-Si electrodes and wirings by a simple method without requiring expensive equipment. The present invention is intended to provide an etching solution composition of

[0010]

In order to solve this problem, the gist of the etching solution composition of the present invention is to be composed of a mixture of hydrofluoric acid, nitric acid and water. In the present invention, the volume ratio of the mixture is 10: hydrofluoric acid, 250: nitric acid,
The summary is that the water is 60.

[0011]

According to the present invention, according to the above-mentioned constitution, the conventional Al and S
It is possible to perform the etching treatment of the Al—Si thin film, which has been subjected to the etching treatment in the two stages of i, by one etching. When the Al-Si thin film etching solution composition of the present invention is applied to the processing of Al-Si electrodes and wirings of a semiconductor element, it can be processed without using an expensive etching apparatus and the process can be simplified. be able to.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing each step of the embodiment of the present invention.

In FIG. 1A, a glass substrate, for example, is used as a substrate to prevent the deposition of impurity atoms from the glass substrate 11 on the glass substrate 11 and prevent the glass substrate 11 from being damaged by the etching solution. Therefore, tantalum oxide 12 is deposited on the entire surface by sputtering.

Next, as shown in FIG. 1B, an Al--Si thin film 13 containing 2% of silicon is deposited on the entire surface of tantalum oxide 12 to a thickness of 200 nm. As a deposition method, a sputtering method, an electron beam evaporation method, or the like is used.

Then, as shown in FIG. 1C, a desired resist pattern 14 is formed on the Al--Si thin film 13 by using a normal photolithography method. At this time, the post-baking temperature of the photoresist has a great influence on the etching shape, but the post-baking is performed at 130 ° C. here.

Then, as shown in FIG. 1D, nitric acid (HNO ₃ ) with a concentration of 60% and 50% with an etching solution are used.
Hydrofluoric acid (HF), acetic acid (CH ₃ COOH), water (H
₂ O) is mixed by volume, and the Al—Si thin film 13 is patterned at room temperature.

Finally, as shown in FIG. 1 (E), Al-
The resist pattern 14 on the Si thin film 13 is removed. Table 1
60% HNO ₃ (250 ml), CH ₃ COOH (1
The etching time, the etching state, and the adhesiveness of the resist when 50% HF is mixed in different amounts in a base liquid composed of 25 ml) and H ₂ O (125 ml) are shown.

[0018]

[Table 1]

From Table 1, the Al-2% Si thin film remains unetched even if the amount of HF mixed is too large or too small, and among the samples in Table 1, the amount of HF mixed is 10 ml.
The best results were obtained. Thus Si
It is considered that the residue-free etching is possible because the Si in the Al—Si thin film reacts with nitric acid to form a Si oxide, which reacts with the mixed HF and is removed by etching. On the other hand, Si residue remains when the amount of HF mixed is large or small, which indicates that a passive film is formed by the mixed solution.

In Table 2, 50% HF (10 ml), 60% H
CH _{3 is} added to the base solution composed of NO ₃ (250 ml)
The etching time, etching state and adhesiveness of resist when ₃ COOH and H ₂ O are mixed in different amounts are shown.

[0021]

[Table 2]

From Table 2, the Al-2% Si thin film contains 6% H ₂ O.
With an etching solution mixed with 0 ml or more, there is no Si residue, or even if there is, it is very small, and good etching can be performed without resist peeling.

Using the above-mentioned mixed amount of the etching solution, A
FIG. 2 shows a scanning electron microscope photograph when the 1-2% Si thin film was etched. 2A shows an example when no Si residue is generated, and FIG. 2B shows an example when the Si residue remains. In these figures, the glass substrate is widened, and an Al-2% Si thin film is formed on the glass substrate.
Although there is a Si residue on the glass substrate in FIG.
In (A), it can be seen that the Si residue on the glass substrate has been removed.

[0024]

As described above, according to the present invention, conventional Al
The etching treatment of the Al-Si thin film, which has been subjected to the etching treatment in two steps of Si and Si, can be performed by one etching. When the Al-Si thin film etching solution composition of the present invention is applied to the processing of Al-Si electrodes and wirings of a semiconductor element, it can be processed without using an expensive etching apparatus and the process can be simplified. It is possible, and the practical effect is great.

[Brief description of drawings]

1A to 1E are cross-sectional views of an Al—Si thin film treated with the etching solution of the present invention in each step.

FIG. 2A is Al treated with the etching solution of the present invention.
The scanning electron microscope photograph in which the Si residue after the etching of the -Si thin film was removed, and (B) is the scanning electron microscope photograph in which the Si residue after the etching of the Al-Si thin film treated with the etching solution of the present invention remained.

3A to 3C are cross-sectional views in which an Al-Si thin film is etched by a conventional etching method twice.

[Explanation of symbols] 11 glass substrate 12 tantalum oxide 13 Al-Si thin film 14 resist pattern

Claims (2)

[Claims] 1. An etching solution composition for an Al--Si thin film, which is composed of a mixture of hydrofluoric acid, nitric acid and water. 2. The volume ratio of the mixture is hydrofluoric acid 10 and nitric acid 25.
2. Al according to claim 1, characterized in that it is 0 and water 60.
-Si thin film etching solution composition.