JPH0368482A - Ultrasonic cleaning device - Google Patents

Abstract

PURPOSE:To maximize cleaning efficiency by providing a means for changing the frequency of an ultrasonic wave generated from a vibrator in accordance with the volume of a cleaning soln. in a tank. CONSTITUTION:A float 3 floated in the cleaning tank 1 to observe the change in the level of a cleaning soln. 2 is connected to a variable resistor 4, and the resistance value of the resistor 4 is changed in accordance with the movement of the float. A converter 5 is formed by a constant current supply circuit, a frequency changing circuit, etc., the voltage of the constant current supply circuit is changed as the resistance value changes, the voltage change is converted to a frequency change by the frequency changing circuit and supplied to the vibrator 6. The ultrasonic wave of the optimum frequency for the level of the cleaning soln. 2 is generated from the vibrator 6, and cleaning efficiency is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an ultrasonic cleaning device used in the manufacturing process of semiconductor devices.

[Conventional technology]

Conventionally, ultrasonic cleaning apparatuses used in the manufacturing process of semiconductor devices, particularly for cleaning wafers, have been of a single frequency type or a multifrequency type.

[Problem to be solved by the invention]

When using the above-mentioned conventional ultrasonic cleaning equipment to clean wafers, it was thought that it would be sufficient to use a single frequency method or a multi-frequency method in order to process a fixed number of wafers, but in reality The number of wafers cleaned in the semiconductor device manufacturing process varies, and the volume of wafers occupying the cleaning tank and the level of the cleaning solution change, so it is important to always use ultrasonic waves at the optimal frequency. figure,
There is a drawback that cleaning efficiency is not improved.

As shown in Fig. 3, when the distance between the vibrator 6 of the ultrasonic cleaning device and the surface of the cleaning liquid 2 is an odd multiple of 1/4 wavelength, the traveling wave of the sound wave emitted from the vibrator 6 This is based on the fact that the reflected waves interfere in the same phase to generate a standing wave, and at this time, the change in sound pressure becomes maximum, forming the sound pressure distribution 10, and the cleaning efficiency also becomes maximum.

[Means to solve the problem]

An ultrasonic cleaning device of the present invention includes a cleaning tank and a vibrator fixed to a lower part of the cleaning tank.
Means is provided for changing the frequency of the ultrasonic waves generated by the vibrator in accordance with the volume of the cleaning liquid in the cleaning tank.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a schematic cross-sectional view of a first embodiment of the present invention.

A cleaning liquid 2 is contained in a cleaning tank 1, and a float 3 is used to float the cleaning liquid 2 in order to observe changes in the liquid level. The float 3 is connected to a variable resistor 4, and the resistance value of the variable resistor 4 changes according to the movement of the float 3.

The converter 5 is composed of a constant current supply circuit, a frequency conversion circuit, etc. When the resistance value of the variable resistor 4 changes, the voltage of this constant current supply circuit changes.The frequency conversion circuit converts this voltage change into a frequency change. It is converted and supplied to the vibrator 6.

As described above, according to the first embodiment, the ultrasonic wave having the optimum frequency depending on the height of the cleaning liquid 2 can be generated in the vibrator 5, so that the cleaning efficiency is improved.

FIG. 2 is a schematic sectional view of a second embodiment of the invention.

The cleaning liquid 2 in the cleaning tank (inner tank) 1 overflows and is stored in an outer tank 3.The cleaning liquid 2 is then circulated and supplied into the cleaning tank 1 via a pump 4 and a filter 5. be done.

In this second embodiment, since the liquid level of the cleaning liquid 2 is always kept constant, efficient ultrasonic cleaning can be performed by supplying a voltage of a constant frequency to the vibrator 6. Furthermore, by removing particles in the cleaning liquid using the filter 5, it is possible to reduce re-adhesion of particles to the object to be cleaned.

〔Effect of the invention〕

As explained above, the present invention has the effect that efficient cleaning can be performed by providing an ultrasonic cleaning device with means for changing the frequency of the ultrasonic waves generated by the vibrator according to the volume of the cleaning liquid. be.

[Brief explanation of drawings]

1 and 2 are schematic sectional views of first and second embodiments of the present invention, and FIG. 3 is a schematic sectional view of a conventional ultrasonic cleaning device. l...Cleaning tank, 2...Cleaning liquid, 3...Float,
4... Variable resistor, 5... Converter 6...
Vibrator, 7...Pump, 8...Filter 9...
・Outer tank, 10...Sound pressure distribution. 1: Trap〉↑糟2: Written by N□Nko;3Kenji 3: Float 4: Kawo Kamehana 5: Hunl\'-Curo: Gofugome Sword Hand

Claims (1)

[Claims] In an ultrasonic cleaning device having a cleaning tank and a vibrator fixed to a lower part of the cleaning tank, means is provided for changing the frequency of the ultrasonic waves generated by the vibrator according to the volume of cleaning liquid in the cleaning tank. An ultrasonic cleaning device characterized by: