Seal for a joint or juncture – Seal between relatively movable parts – Circumferential contact seal for other than piston
Reexamination Certificate
2001-08-02
2004-02-10
Miller, William L (Department: 3677)
Seal for a joint or juncture
Seal between relatively movable parts
Circumferential contact seal for other than piston
C277S913000
Reexamination Certificate
active
06688604
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a sealing mechanism for sealing a vacuum chamber, and more particularly to a sealing mechanism for sealing a vacuum chamber formed in the semiconductor producing apparatus to be shut down from its exterior.
2. Description of the Related Art
In general, the semiconductor producing apparatus of this kind is maintained vacuumized and highly pure in air for producing such products because dusts and other foreign materials are detrimental to wafers and other semiconductor materials in the process of producing the semiconductor producing apparatus. The semiconductor producing apparatus is usually required to be operated by some kinds of driving mechanism such as a manipulator driven by a drive shaft to handle semiconductor devices, LCD base plates and other objects to be treated. The drive shaft has axial portions extending inside and outside of a vacuum chamber formed in the semiconductor producing apparatus. This means that the gaps between the axial portions of the drive shaft and the other parts' around the axial portions of the drive shaft are required to be tightly sealed to have the vacuum chamber maintained at a constant vacuum level.
In recent years, meanwhile, the process of producing semiconductors has remarkably been progressed to obtain more excellent performance, higher density and integration for the products. The process, however, tends to have a relatively low productivity as compared with other industrial products. This is due to the fact that dusts and foreign materials detrimental to wafers and other semiconductor materials are apt to enter the vacuum chamber of the semiconductor producing apparatus. The dusts and foreign materials which may cause inferior products are each made of a particle generally larger than the thickness of an insulator layer to be turned into a semiconductor. At the present time, strenuous efforts continue to be made for reducing to as a lowest level as possible such dusts and foreign materials each having a size larger than the thickness of the insulator layer. These strenuous efforts have not yet become successful.
The typical conventional semiconductor producing apparatus is partly shown in FIG.
15
and FIG.
16
and comprises a manipulator
210
drivably installed in the vacuum chamber
261
of the semiconductor producing apparatus which is vacuumized through an aperture
201
formed in the wall of the semiconductor producing apparatus.
The manipulator
210
is shown in FIG.
15
and
FIG. 16
as having a drive shaft
250
which is rotatably supported on a support member
240
. The wall portion
202
of the semiconductor producing apparatus is formed with a hole
202
a
having the support member
240
fixedly received therein. The drive shaft
250
shown in
FIG. 15
has a forward end portion extending in the vacuum chamber
261
to pivotally support first and second arms
213
and
214
, and a handling member
215
operatively coupled with the first and second arms
213
and
214
so that the handling member
215
can be operated to handle semiconductor devices, LCD base plates and other objects to be treated. Also, the drive shaft
250
has a rear end portion extending in the atmosphere
260
and drivably connected with driving means constituted by an electric motor and reduction gears which are not shown in the drawings.
The drive shaft
250
is shown in
FIG. 16
as comprising a first cylindrical shaft
230
rotatably received in the support member
240
through bearings
216
a
and a second cylindrical shaft
220
rotatably received in the first cylindrical shaft
230
through bearings
216
b.
One typical example of the conventional sealing mechanisms is also shown in
FIG. 16
to comprise a first group
218
of magnetic fluid seals axially arranged between the support member
240
and the first cylindrical shaft
230
, and a second group
219
of magnetic fluid seals axially arranged between the first and second cylindrical shafts
230
and
220
. The two groups
218
and
219
of magnetic fluid seals can function to maintain the vacuum chamber
261
in a hermetically sealed state, resulting in the fact that dusts and foreign materials, i.e., fine particles generated from frictional contacts between elements or parts outside of the vacuum chamber
261
can be prevented from entering the vacuum chamber
261
.
The conventional sealing mechanism mentioned in the above is of a performance having a resistant pressure of 0.2 atmospheric pressure for each of the magnetic fluid seals
218
and
219
. From this reason, the conventional sealing mechanism is required to comprise a plurality of magnetic fluid seals
218
axially disposed in a series between the support member
240
and the first cylindrical shaft
230
, and a plurality of magnetic fluid seals
219
also axially disposed in a series between the first and second cylindrical shafts
230
and
220
as described in the above.
The above known sealing mechanism, however, encounters such a problem that the dusts and foreign materials cannot fully be prevented from entering the vacuum chamber and that the vacuum chamber thus cannot be maintained at a constant vacuum level.
It is, therefore, an object of the present invention to provide a sealing mechanism suitable for sealing a vacuum chamber formed in the semiconductor producing apparatus.
It is another object of the present invention to provide a sealing mechanism having an excellent sealing performance to seal a vacuum chamber formed in the semiconductor producing apparatus.
SUMMARY OF THE INVENTION
According to the first aspect of the present invention there is provided a sealing mechanism for sealing a vacuum chamber formed in the semiconductor producing apparatus, comprising: a rotation shaft driven to be rotatable around its own axis and having an outer surface in the form of a cylindrical shape; a support member intervening between the vacuum chamber and the atmosphere and rotatably supporting the rotation shaft to have the rotation shaft received therein, the support member having an inner surface in the form of a cylindrical hollow shape and first and second axial ends respectively extending in the atmosphere and the vacuum chamber, the inner surface of the support member being larger in diameter than the outer surface of the rotation shaft, the support member being formed with a first fluid passageway having a first end and a second end and a second fluid passageway having a first end and a second end open toward the vacuum chamber; first and second seal rings positioned between the rotation shaft and the support member in axially spaced-apart relationship with each other to hermetically seal the gap between the rotation shaft and the support member under the state that the first seal ring is located in the neighborhood of the first axial end of the support member and remote from the second axial end of the support member and that the second seal ring is located in the neighborhood of the second axial end of the support member and remote from the first axial end of the support member, the rotation shaft, the support member, and the first and second seal rings collectively forming a first fluid chamber held in communication with the first fluid passageway through the first end of the first fluid passageway; an air sucking unit having a port held in communication with the second end of the first fluid passageway to maintain the pressure of the first fluid passageway at a level between the atmospheric pressure and the inner pressure of the vacuum chamber; a third seal ring positioned between the rotation shaft and the support member in axially spaced-apart relationship with the second seal ring between the second seal ring and the extension plane radially inwardly extending and flush with the second axial end of the support member to hermetically seal the gap between the rotation shaft and the support member, the rotation shaft, the support member, and the second and third seal rings collectively forming a second fluid chamber held
Aitken Andrew C.
Anderson Chad C.
Miller William L
Teijin Seiki Co. Ltd.
Venable LLP
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