JPH04130629A - Etchant mixer - Google Patents

Abstract

PURPOSE:To get etchant whose etching rate is stabilized at the early stage after dilution by giving ultrasonic vibration to the chemicals inside a mixing vessel, and supplying gas into the chemical. CONSTITUTION:A circulation filtering means 14 comprises a pump, a pipe, etc., and removes the fine particles inside the mixing liquid, communicating with a mixing vessel 1, and also it agitates the liquid. An ultrasonics oscillating means 15 comprises an ultrasonics generator 15a, a vibrator 15b, etc., and the vibrator 15b is fixed to the bottom of the mixing vessel. A bubbling means 16 communicates with a gas supply means, and discharges gas into the mixing liquid 1 through many small holes. To dilute etchant by this device, respectively specified amounts of undiluted solution and pure water are put in a mixing vessel 11, and ultrasonics are applied to this, and also while bubbling gas, circulation filtering is continued for a specified time.

Description

[Detailed Description of the Invention] [Summary] Regarding the structure of an etching liquid blending device, an object of the present invention is to provide an etching solution blending device that can quickly stabilize the etch rate of the etching solution after blending. The device is configured to include a tank, an ultrasonic vibration means for applying ultrasonic vibration to the chemical liquid in the mixing tank, and a bubbling means for supplying gas into the chemical liquid.

[Industrial application field]

The present invention relates to the structure of an etching liquid preparation device.

In recent years, as the patterns of semiconductor devices have become finer and finer, the influence of the adhesion of fine particles on the wafer on the product yield has become increasingly large in the manufacturing process, particularly in the wafer processing process. Therefore, even in 5ift etching, which is frequently performed in the wafer processing process, preventing fine particles from adhering to the wafer is an important issue, and countermeasures include filtering the etching solution and strengthening air purification. Etching liquids containing surfactants are now being used to suppress the adhesion of fine particles to wafers. This etching solution is made by adding a fluorine-based surfactant to, for example, 50% hydrofluoric acid, and is usually used after adding pure water to dilute it to a desired concentration (eg, 5%).

[Conventional technology]

An example of a conventional etching liquid preparation device will be described with reference to FIG. FIG. 3 is a schematic diagram of a conventional etching liquid preparation device. In the figure, ■ is the blended liquid, 11 is the blending tank, and 1
2 is a stock solution supply means, 13 is a pure water supply means, and 14 is a circulation filtration means consisting of a pump, a filter, piping, etc.

In this etching liquid preparation device, a predetermined amount of the stock solution and pure water are put into a mixing tank 11 by a stock solution supply means 12 and a pure water supply means 13, respectively, to form a preparation solution I, and this is supplied to a circulating filtration means 1.
4 to remove fine particles and stir the solution to obtain a diluted etching solution with a desired concentration.

There is also an example in which a mechanical stirring means (not shown) is provided in the mixing tank 1 instead of the circulation filtering means 14.

[Problem to be solved by the invention]

However, when using such an apparatus and diluting an etching solution made of 50% hydrofluoric acid with a fluorine-based surfactant added with pure water, the etch rate for 5 iOz is low immediately after dilution.
After that, the etching solution gradually becomes high (and becomes stable over a long period of time), and after dilution, it cannot be used for a long period of time, so a large amount of diluted etching solution must be stored.
There was a problem.

SUMMARY OF THE INVENTION An object of the present invention is to solve these problems and provide an etching solution preparation device that can obtain an etching solution whose etch rate is stabilized quickly after dilution.

[Means to solve the problem]

According to the present invention, this object is characterized by comprising a mixing tank, an ultrasonic vibration means for applying ultrasonic vibration to the chemical liquid in the mixing tank, and a bubbling means for supplying gas into the chemical liquid. This can be achieved by using an etching liquid preparation device that does this.

[Effect]

Ultrasonic vibration and bubbling have effects such as stirring and defoaming.
It seems to promote the dispersion of the surfactant.

〔Example〕

A first embodiment of the etching liquid preparation device according to the present invention is described below.
This will be explained with reference to the figures and FIG.

FIG. 1 is a schematic diagram of an etching liquid preparation apparatus according to an embodiment of the present invention. In the figure, l is the blended liquid, 11 is the blending tank, and 12
13 is a pure water supply means, 14 is a circulating filtration means, 15 is an ultrasonic vibration means, and 16 is a bubbling means.

The circulation filtration means 14 is composed of a pump, a filter, piping, etc., and communicates with the mixing tank 11 to remove particulates from the mixed liquid I and to stir the liquid. The ultrasonic excitation means 15 includes an ultrasonic generator 15a, a vibrator 15b, etc., and the vibrator 15b is fixed to the bottom of the mixing tank 11. The bubbling means 16 communicates with a gas supply means (not shown) and releases gas into the liquid mixture 1 from a large number of small holes.

To dilute the etching solution using this device, predetermined amounts of the stock solution and pure water are placed in a mixing tank II, and while applying ultrasonic vibration and gas bubbling, circulation filtration is continued for a predetermined period of time.

FIG. 2 shows the results of diluting a stock solution of an etching solution prepared by adding a fluorine-based surfactant to 50% hydrofluoric acid with pure water to 5% hydrofluoric acid using this apparatus. This involves circulating filtration of a blended liquid with a liquid volume of 51 for 2 hours while performing ultrasonic vibration using an ultrasonic generator with an ultrasonic frequency of 41 kHz and a high-frequency output of 35 W, and bubbling purified helium gas. The change in etch rate over time with respect to 5 ift is shown by a solid line. For reference, the result of continuous circulation filtration of the above-mentioned liquid mixture with a liquid volume of 51 for 2 hours using a conventional device is shown in the same figure with a dotted line. The dotted line takes about 20 days to stabilize, while the solid line takes about 2 days to stabilize. As is clear from the figure, 5i of the etching solution diluted by the etching solution preparation device of the present invention.
The etch rate for 02 becomes stable in a very short period of time after dilution and becomes usable.

The present invention is not limited to the above embodiments, but can be implemented with various modifications. For example, it is possible to use a gas other than helium as the bubbling gas.

[Effects of the Invention] As explained above, according to the present invention, it is possible to provide an etching liquid preparation device that can quickly stabilize the etch rate of the etching liquid after preparation, and to process a large amount of diluted etching liquid. There is no need to store etching solution.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of an etching liquid preparation apparatus according to an embodiment of the present invention, FIG. 2 is a graph showing changes in etching rate over time, and FIG. 3 is a schematic diagram of a conventional etching liquid preparation apparatus. In the figure, ■ is a mixed liquid, 11 is a mixing tank, 12 is a stock solution supply means, 13 is a pure water supply means, 14 is a circulating filtration means, is an ultrasonic vibration means, and is a bubbling means. 12J yo night damage r mortar + j2 Suemitsuho's great precedent work, 1000 years old survey order IJ/Mu4; Composition diagram light transmission - 1 record (b) ball, + L - / 7 transverse modelization standard, 'T7゛゛゛゛゛　　〆〆〆)〆゛゛゛゛゛゛゛　〆〆〆)〆〆゛゛゛゛゛゛゛　〆〆〆)

Claims (1)

[Claims] An etching solution mixing device comprising: a mixing tank; ultrasonic vibration means for applying ultrasonic vibration to a chemical solution in the mixing tank; and bubbling means for supplying gas into the chemical solution.