Pipe joints or couplings – Having plural independent paths – Allowing relative motion of pipes
Reexamination Certificate
1999-10-15
2002-07-02
Matecki, Kathy (Department: 3627)
Pipe joints or couplings
Having plural independent paths
Allowing relative motion of pipes
C285S041000, C285S140100, C285S121100, C277S937000, C277S941000
Reexamination Certificate
active
06412822
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to rotary joints for fluids, and more specifically to rotary joints that allow fluids—such as polishing solution for polishing the surface of silicon wafer by the chemical mechanical polishing (CMP) technique—to flow through the components that rotate relative to one another.
2. Description of the Prior Art
An apparatus for polishing the surface of silicon wafers by CMP, to which this invention relates, has been developed in recent years. The apparatus, as shown in
FIGS. 10 and 11
, comprises: a rotary table
102
that rotates horizontally; a pad shaft support block
103
which moves horizontally back and forward and up and down; a polishing pad shaft
104
which, held by the pad shaft support block
103
, is forced to rotate; a slurry fluid feeding and discharging passage
105
formed on the non-rotary side in the pad shaft support block
103
; a feeding and discharging mechanism
107
connected to the slurry fluid feeding and discharging passage
105
for a polishing solution
106
, for example, a KOH-contained silica slurry mixed in isopropyl alcohol; a slurry fluid feeding and discharging passage
108
on the rotary side which runs through the polishing pad shaft
104
and opens at the central portion of a pad head
104
a;
and a rotary joint
101
which, installed between the pad shaft support block
103
and the polishing pad shaft
104
, connects the two slurry fluid feeding and discharging passages
105
and
108
in such a way that the two passages
105
and
108
are relatively rotatable when communicating with each other.
By that surface polishing apparatus, the silicon wafer
109
is polished in this way: first, the silicon wafer
109
is held on the rotary table
102
, the surface
109
a
up, and the polishing pad shaft
104
is moved down until the pad head
104
a
comes into contact with the wafer surface
109
a.
Then, the polishing solution
106
is jetted out to between the pad head
104
a
and the wafer
109
by means of positive pressure action (jetting operation of the polishing solution pump) of the feeding and discharging mechanism
107
. And the polishing pad shaft
104
is rotated and moved back and forward horizontally to polish the wafer surface
109
a.
After polishing is over, the feeding and discharging mechanism
107
is switched to negative pressure action (sucking operation of the polishing solution pump) to suck and remove the residues of the polishing solution
106
in the slurry fluid feeding and discharging passages
105
and
108
. That is, care is taken so that the residues of the polishing solution
106
in the slurry fluid feeding and discharging passages
105
and
108
may not drop on the polished surface of the wafer, and that is effected by switching the slurry fluid feeding and discharging passages
105
,
108
from the positive pressure mode to the negative pressure or dry mode.
The rotary joint
101
mounted in that surface polishing apparatus is designed as in the following. A first joint body, which is to be mounted on the pad shaft support block
103
, is connected to a second joint body, which is to be fixed on the polishing pad shaft
104
such that the firs joint body and the second joint body may rotate relative to one another. Within the first joint body is formed a first fluid passage section which is connected to the slurry fluid feeding and discharging passage
105
on the non-rotary side. In the second joint body on the rotary side is formed a second fluid passage section that is connected to the slurry fluid feeding and discharging passage
108
. A space formed between the two slurry fluid passage sections is sealed with a sealing member placed between the relatively rotating opposed faces of the first joint body and the second joint body. An example of such a sealing member is sealing faces formed on the opposing parts of the relatively rotating first and second joint bodies that are brought into contact with and pressed against each other. Another example to seal the relatively rotating parts is elastic seal materials such as O-ring.
The rotary joint
101
of such a design presents the following problems. That is, the polishing solution
106
is a slurry fluid containing abrasive grains. Those abrasive grains tend to intrude and be deposited between the sealing faces, making it difficult to keep the sealing function in a good shape for a long period. Also, the sealing faces will be worn in contact with the polishing solution
106
, losing sealing function in a short period. Another problem is that wear particles from the seal faces and ingredients dissolving out of the elastic seal will get mixed in polishing solution
106
, hampering the polishing of wafer surface
109
a.
The intrusion and deposition of such abrasive grains and the wearing of the sealing faces occur more evidently in particular by switching the slurry fluid feeding and discharging passages
105
,
108
from positive pressure to negative pressure or dry mode. Especially in the dry mode, in addition, seizure will be inflicted on the sealing faces because of frictional heat. If the intrusion and deposition of abrasive grains and the wearing of the sealing faces affect the seal performance, polishing solution
106
can leak out of the sealing faces, causing such problems as staining wafer surface
109
a
and creeping into the bearings between the first and second joint bodies and hindering the polishing pad shaft
104
from rotating smoothly. And good polishing could hardly be hoped for of such a rotary joint
101
.
Those problems are encountered with the prior art rotary joint
101
not only in the aforesaid surface polishing apparatus but in a rotary equipment in which a slurry fluid like polishing solution or a corrosive fluid must flow between component parts rotating at a rate higher than a certain level. Such being the case, it has been keenly desired that a solution to the problems should be found, but the fact is that no rotary joint for fluids has been developed which exhibits a stabilized sealing performance for a long time.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a rotary joint which permits smooth flow of a flurry fluid such as a polishing solution or a corrosive fluid through relatively rotating component parts without leakage and which makes a surface polishing apparatus or other equipment properly perform the functions as mentioned earlier.
It is another object of the present invention to provide a rotary joint that always exhibits a good and stable sealing performance irrespective of the sealing conditions such as the pressure and properties of fluid, thus perfectly preventing the contamination of fluids and the environment and which is suitable for use in a variety of equipment where a high degree of cleanness is required.
It is still another object of the present invention to provide a rotary joint which permits simultaneously smooth flow between the two joint bodies of a slurry fluid like polishing fluid and one or more kinds of liquids or gases, thus opening up a wide range of applications.
It is yet another object of the present invention to provide a rotary joint that can be reduced in size to a maximum extent.
Those objects are attained by a rotary joint constructed according to the present invention.
The rotary joint of the present invention comprises: a first joint body; a second joint body connected to the first joint body such that the second joint body is allowed to rotate in relation the first joint body; and a prime seal unit installed between opposed end portions of the two joint bodies, the opposed end portions arranged in the direction of the axis of rotation; and a continuous line of prime fluid passage which runs through the two joint bodies. The prime seal unit is a mechanical seal comprising: a stationary seal ring fixed concentrically on one of the opposed end portions of the two joint bodies with the axis of rotation as its center; a movable seal ring held on the other of the op
Omiya Junyi
Wada Masato
Griffin & Szipl, P.C.
Lugo Carlos
Matecki Kathy
Nippon Pillar Packing Co. Ltd.
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