Cleaning and liquid contact with solids – Processes – Including application of electrical radiant or wave energy...
Reexamination Certificate
2000-05-17
2001-01-30
Coe, Philip R. (Department: 1746)
Cleaning and liquid contact with solids
Processes
Including application of electrical radiant or wave energy...
Reexamination Certificate
active
06178974
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an apparatus and method for cleaning an object to be cleaned, such as a wafer or the like, using for example ultrasonic vibration.
DESCRIPTION OF THE RELATED ART
A cleaning apparatus, in which an object to be cleaned such as a wafer is immersed in cleaning fluid and the cleaning fluid is ultrasonically vibrated or oscillated, is well known. In order to enhance the cleaning power of such kinds of ultrasonic cleaning apparatus, various attempts have been made.
In, for example, Japanese Unexamined Patent Publication No. 6(1994)-320124, is described an ultrasonic cleaning apparatus that enhances the ultrasonic cleaning power by pouring fine air-bubbles into the cleaning fluid. Also, in Japanese Unexamined Patent Publication No. 8(1996)-141527, is described an ultrasonic cleaning apparatus in which the residue is exfoliated and removed by using an ultrasonic vibrator that vibrates at different frequencies. Furthermore, in Japanese Unexamined Patent Publication No. 8(1996)-108155 is described a cleaning apparatus that cleans an object to be cleaned with the object obliquely attached to the ultrasonic vibrator.
As mentioned above, according to the conventional cleaning apparatuses, the residue and dirts adhered to the object to be cleaned can be removed to some extent. However, polished tailings and residues confined in a groove of the object to be cleaned could not positively be removed.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a cleaning apparatus and a cleaning method that can substantially positively remove polished tailings and residues confined in grooves of the object to be cleaned.
According to the present invention, a cleaning apparatus includes a cleaning tank for reserving cleaning fluid, an object to be cleaned being immersed in the cleaning fluid, a vibrator for vibrating the cleaning fluid in the cleaning tank, and two micro-vibration sources for minutely vibrating the object to be cleaned in two different directions.
Furthermore, according to the present invention, a cleaning method for cleaning an object to be cleaned, has a step of immersing the object in cleaning fluid, a step of vibrating the cleaning fluid, and a step of minutely vibrating the object in two different directions during the vibration of the cleaning fluid.
The cleaning fluid in the cleaning tank is vibrated by a vibrator and, at the same time, an object to be cleaned is minutely vibrated in two different directions. Cleaning non-uniformities due to the vibrator cavitation can be removed by minutely vibrating the object to be cleaned in two different directions by two micro-vibration sources.
It is preferred that the vibrator produces pressure distribution in the cleaning fluid in the cleaning tank, and that at least one of the micro-vibration sources presents to the object micro-vibration in a direction vertical and/or parallel to an advance direction of the pressure distribution.
It is also preferred that the two micro-vibration sources presents to the object micro-vibrations in two directions orthogonal to each other. Such crossing of vibration directions at right angle can facilitate the removal of polished tailings and residues confined in grooves or the like.
It is preferred that the vibrator produces pressure distribution in the cleaning fluid in the cleaning tank, and that at least one of the micro-vibration sources is rocked in a direction parallel to an advance direction of the pressure distribution.
It is further preferred that the cleaning tank has a wall to which the vibrator is attached, and that the two micro-vibration sources are rocked in a direction vertical to a surface of the wall of the cleaning tank. When the vibrator is attached to one wall surface of the cleaning tank, a sound pressure distribution is generated between this wall surface and opposite wall surface of the cleaning tank in the cleaning fluid in the cleaning tank. A larger cleaning effect is obtained at the maximum point in the sound pressure change and a smaller cleaning effect is obtained at the minimum point in the sound pressure change, thereby generating a cleaning non-uniformities. When the wall surface to attach the vibrator is a bottom surface, the opposite wall surface is a fluid surface. Oscillation of the minute vibration source in a direction vertical to this attaching wall surface oscillates the object to be cleaned along this sound pressure distribution. Accordingly the object does not remain only at the maximum or minimum point in the sound pressure change, thereby removing the cleaning non-uniformities.
It is preferred that the micro-vibration sources consist of oscillating horns.
Preferably, the vibrator is an ultrasonic oscillator and/or the micro-vibration sources are ultrasonic oscillators.
Further, objects and advantages of the present invention will be apparent from description of the preferred embodiments of the invention in the accompanying drawing.
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Kobayashi Kanji
Kubota Toshio
Kudo Jun
Yamaguchi Masao
Yoshihara Shinya
Arent Fox Kintner & Plotkin & Kahn, PLLC
Coe Philip R.
TDK Corporation
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