JP3473451B2 - Etching method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an etching method for forming electrodes and aluminum and aluminum alloy thin films as wiring materials on a substrate of silicon, glass, ceramics or the like.

[0002]

2. Description of the Related Art A mixture of phosphoric acid, nitric acid, acetic acid and water is used as an etching solution for forming electrodes and wirings made of aluminum or aluminum alloy thin film on a substrate made of silicon, glass, ceramics or the like.

[0003]

However, in the phosphoric acid-nitric acid-acetic acid-water system, there is a problem that the working environment is deteriorated due to the odor of acetic acid which is one component of the mixture. Furthermore, the acetic acid odor causes the waste liquid having lost the etching function to be difficult to reuse in other industrial fields.

[0004]

In order to solve the above-mentioned drawbacks, the present inventor reported in Japanese Patent Application No. 322055 a mixture of phosphoric acid-nitric acid-citric acid-water composition as an etching solution composition. In the present invention, as the etching solution composition, instead of a mixture of phosphoric acid, nitric acid, acetic acid and water, a mixture of phosphoric acid, nitric acid, citric acid, malonic acid and water, or phosphoric acid, nitric acid, malonic acid and water. A mixture having the composition of was used.

[0005]

As a result, it has been confirmed that the performance as an etching solution is almost equal to or superior to that of the conventional technique, and at the same time, no bad odor such as acetic acid is generated. confirmed. The advantage over the prior art is that, first of all, the odor of the etching solution was reduced, which made the working environment extremely good, and there were various methods for treating the waste solution of the etching solution. It became easier to reuse. Second, it was found that the fluctuation range of the etching rate was smaller than that of the conventional technique even if the fluctuation range of the composition of the etching solution was large. This makes it easier to control the etching.
The smoothness of the etched surface was almost the same as that of the conventional method. Third, it was found that the fluctuation range of the etching rate was smaller than that of the conventional technique even if the fluctuation range of the liquid temperature was large.
This also makes it easy to control etching. Fourthly, as etching progresses, the amount of Al dissolved in the etching solution increases. In this case, it was found that the decrease in the etching rate was smaller than that in the conventional technique even if the amount of Al dissolved increased.

[0006]

Embodiments of the present invention will be described in detail below in comparison with the prior art. Regulating the etchant various compositions
It was manufactured and subjected to etching test at 40 ° C. ± 0.5 ° C. of liquid temperature. As the Al electrode, 99.9% Al was used, and as the etching liquid composition, a primary reagent and ion-exchanged water were used. In the prior art, the mixing ratio of phosphoric acid-nitric acid-acetic acid-water is determined by the electrodes, etching conditions, and electrode design goals. In this embodiment, the weight ratio is 85% phosphoric acid: 85.5-70% nitric acid. : 4.5-99% acetic acid: 6.
5-Water: 3.5 was used as a standard, and the blending ratio of the technique of the present invention was set so as to be the same as the etching rate of this formulation.

Example 1 For prior art formulations, 85% by weight phosphoric acid:
85.5-70% nitric acid: 4.5-99% acetic acid: 6.5-
An etching solution of water: 3.5 was prepared, and for the formulation of the present invention, 85% phosphoric acid: 83.0-70% nitric acid: 6.5-99% citric acid: 3.4-99% by weight. An etching solution of malonic acid: 1.0-water: 6.0 was prepared . They had the same etching rate and were subjected to a comparative etching test for both formulations.
As a result, it was confirmed that the technique of the present invention has no acetic acid odor as compared with the conventional technique, and that the smoothness of the etching surface is almost the same as that of the conventional technique.

Example 2 For the prior art formulation, 85% phosphoric acid by weight:
85.5-70% nitric acid: 4.5-99% acetic acid: 6.5-
An etching solution of water: 3.5 was prepared, and in the formulation of the present invention, by weight, 85% phosphoric acid: 84.5-70% nitric acid: 5.0-99% malonic acid 2.4-water: 8 An etching solution of 0.0 was prepared . They had the same etching rate and were subjected to a comparative etching test for both formulations. As a result, the technique of the present invention had no acetic acid odor as compared with the conventional technique, and the smoothness of the etching surface was almost the same as that of the conventional technique.

Example 3 In Example 1, 70% nitric acid and 85% phosphoric acid in the formulations of the prior art and the present invention were increased or decreased by ± 1% each by weight (the amount of increase or decrease was adjusted with water to 10%).
Etching test was performed. as a result,
Regarding the etching rate, the technique of the present invention showed less variation in the etching rate than the conventional technique.

Example 4 In Example 2, 70% nitric acid and 85% phosphoric acid in the formulations of the prior art and the present invention were increased / decreased by ± 1% each (the amount of increase / decrease was adjusted with water to 10%).
Etching test was performed (0%). As a result, regarding the etching rate, the variation of the etching rate of the present invention was smaller than that of the conventional technique.

[Embodiment 5] With respect to the influence of the temperature of the etching solution, an etching test was conducted by comparing the technique of the present invention of Example 1 and the technique of Example 2 with the prior art. The results are shown below.

[Embodiment 6] With respect to the influence of Al concentration in the etching solution, an etching test was carried out by comparing the technique of the present invention in Example 1 as well as in Example 2 with the conventional technique. The results are shown below.

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Claims (2)

(57) [Claims] 1. An etching method for forming an aluminum or aluminum alloy thin film as an electrode or wiring material on the surface of a substrate such as silicon, glass or ceramics, wherein phosphoric acid, nitric acid, citric acid or malonic acid is used. , Aluminum or aluminum in a mixed acid consisting of a mixture of water composition
An etching method comprising etching an alloy thin film . 2. A substrate made of silicon, glass, ceramic or the like.
On the surface of the electrode, aluminum or aluminum as wiring material
The etching method for forming a thin film of a nickel alloy
And then etching the aluminum or aluminum alloy thin film with a mixed acid consisting of a mixture of phosphoric acid, nitric acid, malonic acid and water .