JP2000100778A - Etching liquid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate the smell of acetic acid, to improve the working environment for manufacturing an etchant and to facilitate waste disposal of the etching liquid concerning the etching liquid, when an electrode and a wiring material, which consist of an aluminium film and an aluminium alloy thin film are formed on a substrate, such as a silicon substrate, a ceramic substrate and a glass substrate. SOLUTION: A mixture of the composition of phosphoric acid with nitric acid, citric acid, malonic acid and water or the mixture of the composition of phosphoric acid with nitric acid, malonic acid and water is used as an etchant instead of the mixture of phosphoric acid with nitric acid, acetic acid and water, which is prepared conventional techniques. As a result, these mixtures were roughly equal with the mixture prepared by the conventional techniques in the flatness of an etching surface, but the smell of acetic acid disappeared and it has been found that the working environment for manufacturing the etching liquid can be improved because of it and at the same time, recycling becomes easy to promote also about the disposal of the waste fluid of the etching liquid. Moreover, in this method, it is hardly affects the fluctuations of the composition of the etching liquid, the fluctuations in the temperature of the etching liquid and the elution of Al in the etching liquid as compared with the conventional technique and a stable etching can be promoted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an etching solution for forming aluminum and aluminum alloy thin films as electrodes and wiring members on a substrate made 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 of aluminum and aluminum alloy thin films on a substrate 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. Further, the odor of acetic acid also makes it difficult to reuse the waste liquid having lost the etching function 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 and water as the composition of an etching solution. In the present invention, instead of the mixture of phosphoric acid, nitric acid, acetic acid, and water, the mixture of the composition of phosphoric acid, nitric acid, citric acid, malonic acid, and water or the mixture of phosphoric acid, nitric acid, malonic acid, and water are used in the present invention. A mixture of the following composition was used.

[0005]

As a result, it was confirmed that the performance as an etching solution was almost the same as or superior to that of the prior art, and at the same time, there was no odor such as acetic acid odor. confirmed. The advantages over the prior art are that, first of all, the odor of this etchant has been reduced, resulting in a very good working environment. Reuse has become easier. Secondly, it has been found that even if the amount of variation of the composition of the etching solution is large, the variation of the etching rate is small as compared with the prior art. This makes it easier to control the etching.
The smoothness of the etched surface was almost the same as the conventional method. Third, it was found that even if the fluctuation range of the liquid temperature was large, the fluctuation range of the etching rate was smaller than that of the conventional technique.
This also makes it easier to control the etching. Fourth, as the etching progresses, the amount of Al dissolved in the etchant increases. In this case, it was found that even when the amount of Al dissolved increased, the decrease in the etching rate was small compared to the conventional technology.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be described in detail below in comparison with the prior art. Etching solutions having various compositions were prepared, and an etching test was performed at a solution temperature of 40 ° C. ± 0.5 ° C. 99.9% Al was used for the Al electrode, and a first-class reagent and ion-exchanged water were used for the etching solution composition. In the prior art, the mixing ratio of phosphoric acid-nitric acid-acetic acid-water is determined by the electrode, etching conditions, and electrode design goals, but in this embodiment, 85% phosphoric acid: 85.5-70% nitric acid by weight. : 4.5-99% acetic acid: 6.
5-Water: 3.5 was used as a standard, and the mixing ratio of the present technology was set so as to be the same as the etching rate of this formulation.

[Example 1] [0007] For the prescription of the prior art,
85% phosphoric acid: 85.5-70% nitric acid by weight ratio: 4.
An etching solution of 5-99% acetic acid: 6.5-water: 3.5 was prepared, and for the formulation of the present invention, 85% phosphoric acid: 83.0-70% nitric acid: 6.5-99 by weight ratio. % Citric acid: 3.4-99% malonic acid: 1.0-water: 6.0 was prepared as an etching solution. The etching rates were adjusted to be the same, and a comparative test of etching was performed for both formulations. As a result, it was confirmed that the odor of acetic acid was eliminated in the technique of the present invention as compared with the conventional technique, and that the smoothness of the etched surface was almost the same as that of the conventional technique.

Example 2 For the prior art formulation,
85% phosphoric acid: 85.5-70% nitric acid by weight ratio: 4.
An etching solution of 5-99% acetic acid: 6.5-water: 3.5 was prepared, and for the formulation of the present invention, 85% phosphoric acid: 84.5-70% nitric acid: 5.0-99 by weight ratio. % Malonic acid 2.4-water: An etching solution of 8.0 was prepared. The etching rates were adjusted to be the same, and a comparative test of etching was performed for both formulations. As a result, the odor of acetic acid was eliminated in the technique of the present invention as compared with the conventional technique, and the smoothness of the etched 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 each increased or decreased by ± 1% by weight (the amount of increase or decrease was adjusted by water to 10%).
0%), and an etching test was performed. as a result,
Regarding the etching rate, the fluctuation of the etching rate was small in the present invention technology compared to the conventional technology.

[Example 4] In Example 2, 70% nitric acid and 85% phosphoric acid in the formulations of the prior art and the present invention were each increased or decreased by ± 1% by weight.
(Set to 0%). As a result, with respect to the etching rate, the variation of the etching rate was small in the present technology compared to the conventional technology.

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

[Embodiment 6] With respect to the influence of the Al concentration in the etching solution, an etching test was conducted by comparing the present invention technique and the conventional technique in Embodiment 1 and Embodiment 2 with each other. The results are shown below.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4K057 WA18 WA20 WB05 WE02 WE04 WE13 WN01 WN02 5E339 AB05 AB06 BC03 BE13 BE17 5F043 AA24 BB16 DD07 GG02 GG04 GG10

Claims (2)

[Claims] A mixture of phosphoric acid, nitric acid, citric acid, malonic acid, and water in etching for forming an aluminum or aluminum alloy thin film as an electrode and a wiring material on the surface of a substrate such as silicon, glass, or ceramic. Characterized by etching with a mixed acid consisting of 2. An etching method characterized by etching with a mixed acid comprising a mixture of phosphoric acid, nitric acid, malonic acid and water.