Cleaning and liquid contact with solids – Apparatus – With movable means to cause fluid motion
Reexamination Certificate
2001-02-20
2003-03-18
Coe, Philip (Department: 1746)
Cleaning and liquid contact with solids
Apparatus
With movable means to cause fluid motion
Reexamination Certificate
active
06532977
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a long-lived cleaning vessel for ultrasonic cleaning, which is easily manufactured and is also easy to handle due to a simple structure thereof and which has excellent durability, mechanical strength, and resistance to corrosion. Further, the present invention also relates to a silicon carbide sintered body which propagates ultrasonic waves, and particularly to a silicon carbide sintered body of high density and high purity, which can be applied to components for semiconductor production apparatuses, components for electronic information equipment, and various structural components for vacuum devices and the like, and which can suitably be used as an ultrasonic resonance plate or an ultrasonic diaphragm.
2. Description of the Related Art
Conventionally, ultrasonic cleaning which allows cleaning of materials to be cleaned by means of ultrasonic waves, has been carried out in various fields. In the above-described ultrasonic cleaning, a material to be cleaned is immersed in a cleaning liquid accommodated in a cleaning vessel. An ultrasonic oscillator disposed at the bottom of the cleaning vessel is oscillated at a predetermined frequency. As a result, ultrasonic vibration is induced in the cleaning liquid, and impurities such as oil or dust, which adhere to the surface of the material to be cleaned, and to the vicinity thereof, are removed due to cavitation of the cleaning liquid.
As the cleaning vessel used for the above-described ultrasonic cleaning, conventionally, for example, a cleaning vessel
10
as shown in
FIG. 3
has been known. The cleaning vessel
10
includes an outer cleaning vessel
12
made of metal, resin, or the like, and an inner cleaning vessel
11
disposed to be accommodated in an interior of the outer cleaning vessel
12
. An ultrasonic propagation medium
13
is accommodated in a clearance formed between the outer cleaning vessel
12
and the inner cleaning vessel
11
, and an ultrasonic oscillator
5
is disposed at the bottom of the outer cleaning vessel
12
. It is advantageous to use, as the cleaning liquid, a liquid such as acid, having a strong corrosiveness, from the standpoint of improving cleaning efficiency of the material to be cleaned. Therefore, conventionally, the inner cleaning vessel
11
has been generally made of quartz in a case of acid cleaning.
However, the inner cleaning vessel
11
made of quartz or the like has a problem in that it is apt to be deteriorated and broken by ultrasonic waves and durability thereof deteriorates, and particularly, such defects are remarkably caused in a peripheral edge portion at the bottom of the vessel. Further, there exists a problem in that propagation of ultrasonic waves is interfered and cleaning efficiency thereby deteriorates. Moreover, there also exists a problem in that sufficient corrosion-resistance to hydracid fluoride is not obtained and the vessel cannot be used when hydrofluoric acid or mixture of hydrofluoric acid and nitric acid, which is used very often for cleaning of semiconductor materials, is used as the cleaning liquid.
Furthermore, in the fields of semiconductors and ultrasonic vibration, quartz components which have been conventionally used, deteriorate or degenerate due to cleaning using chemicals such as hydrofluoric acid. Therefore, there has recently been remarked a high density silicon carbide sintered body having excellent resistance to heat, in which the above-described problems are not caused. Particularly, in the field of ultrasonic vibration, it is necessary that a silicon carbide sintered body propagates ultrasonic waves. Desirably, a sound velocity of propagated ultrasonic waves may be increased.
SUMMARY OF THE INVENTION
An object of the present invention is to solve the above-described conventional problems and achieve the following object. That is, an object of the present invention is to provide a long-lived cleaning vessel used for ultrasonic cleaning, which is easily manufactured and is also easy to handle due to a simple structure thereof and which has excellent durability, mechanical strength, and resistance to corrosion.
As a result of their diligent studies for solving the above-described problems, the present inventors noted that ultrasonic waves contacting a material to be cleaned, which is accommodated within a cleaning vessel, are apt to be reflected and propagated through a peripheral edge at the bottom of the cleaning vessel, the peripheral edge at the bottom of the cleaning vessel is apt to be broken due to the ultrasonic waves, and a portion in which the ultrasonic waves are introduced, is also apt to be broken due to the ultrasonic waves.
The present invention has been devised based on the above-described extended researches of the present inventors, and the above-described problem is solved by the following means.
In accordance with a first aspect of the present invention, there is provided a cleaning vessel for cleaning a material to be cleaned, by introducing therein ultrasonic waves, the cleaning vessel comprising a cleaning vessel main body in which the material to be cleaned is accommodated together with a cleaning liquid, and a layer of silicon carbide sintered body which propagates ultrasonic waves, wherein the layer of silicon carbide sintered body is formed at an inner side of the cleaning vessel main body at least on a bottom peripheral edge portion of the cleaning vessel main body and on a portion in which the ultrasonic waves are introduced.
In accordance with a second aspect of the present invention, the layer of silicon carbide sintered body is comprised of a silicon carbide sintered body of which density is 2.9 g/cm
3
or greater.
In accordance with a third aspect of the present invention, the layer of silicon carbide sintered body is comprised of a silicon carbide sintered body in which the total content of elements other than Si, C, O, N, halogen, and rare gas is 10 ppm or less.
In accordance with a fourth aspect of the present invention, the layer of silicon carbide sintered body is comprised of a silicon carbide sintered body of which volume resistivity is 1 &OHgr;·cm or less.
In accordance with a fifth aspect of the present invention, the layer of silicon carbide sintered body is comprised of a silicon carbide sintered body which can be heated by turning on electricity.
In accordance with a sixth aspect of the present invention, the layer of silicon carbide sintered body formed on the bottom peripheral edge portion at the inner side of the cleaning vessel main body, has a passage for a cooling medium.
In accordance with a seventh aspect of the present invention, providing that a wavelength of introduced ultrasonic waves is &lgr;, an acoustic velocity of the ultrasonic waves is &ugr;, and a frequency of the ultrasonic waves is f, thickness (b) of the layer of silicon carbide sintered body when oscillated a wavelength l/m, is represented by the following expression:
b=
(&lgr;/
m
)
n=
(&ugr;/
mf
)
n
(n represents an integer).
In accordance with an eighth aspect of the present invention, the layer of silicon carbide sintered body is formed on an entire surface at an inner side of the cleaning vessel main body.
In accordance with a ninth aspect of the present invention, the cleaning vessel main body has a heat resisting temperature of 120° C. or higher.
In accordance with a tenth aspect of the present invention, the cleaning vessel main body has high chemical resistance.
In accordance with an eleventh aspect of the present invention, the cleaning vessel main body is made of thermosetting resin.
In accordance with a twelfth aspect of the present invention, the thermosetting resin is any one of polyvinyl chloride and polytetrafluoroethylene.
According to the first aspect, the cleaning vessel is comprised of the cleaning vessel main body in which the material to be cleaned is accommodated together with the cleaning liquid, and the layer of silicon carbide sintered body. When ultrasonic waves are oscillated from an outer side to an inn
Endo Shigeki
Murakawa Yuka
Otsuki Masashi
Bridgestone Corporation
Coe Philip
Oliff & Berridg,e PLC
LandOfFree
Cleaning vessel and silicon carbide sintered body used therefor does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Cleaning vessel and silicon carbide sintered body used therefor, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Cleaning vessel and silicon carbide sintered body used therefor will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3014986