Abrading – Work feeder – Ejector or unloader
Reexamination Certificate
1999-12-15
2002-02-12
Banks, Derris H. (Department: 3723)
Abrading
Work feeder
Ejector or unloader
C451S041000, C451S288000, C451S391000
Reexamination Certificate
active
06346038
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a wafer loading/unloading device which attaches a wafer to be polished to a polishing head and which receives the wafer that has undergone polishing on the polishing head from the polishing head, and to a method of producing wafers by using this apparatus.
2. Description of the Related Art
Generally speaking, in a wafer polishing apparatus for polishing the surface of semiconductor wafers, a wafer polishing head holding the wafer and a platen to which a polishing pad is attached are opposed to each other, and polishing is effected by causing the wafer polishing head to make planetary motion on the polishing pad while pressing the surface of the wafer against the polishing pad and supplying slurry containing abrasive.
As shown in
FIG. 12
, an example of such a polishing head comprises a head main body
53
composed of a top plate portion
51
and a cylindrical peripheral wall portion
52
fastened to the outer periphery of the top plate portion
51
, a diaphragm
54
consisting of an elastic material such as rubber stretched inside the head main body
53
, a pressure adjusting mechanism
56
for adjusting the pressure in a fluid chamber
58
, a disc-like carrier
55
fastened to the lower surface of the diaphragm
54
, and an annular retainer ring
57
concentrically arranged in the outer periphery of the carrier
55
.
The carrier
55
and the retainer ring
57
are respectively fixed to a carrier fixing ring
59
and a retainer ring fixing ring
62
provided on the upper side of the diaphragm
54
, and the retainer ring
57
is arranged concentrically, with a slight gap being provided between the outer peripheral surface of the carrier
55
and the peripheral wall portion
52
. When polishing a wafer, a wafer
70
is attached, for example, by vacuum suction, to a wafer attachment sheet
71
provided on the lower side of the carrier
55
, with its outer periphery being engaged with the retainer ring
57
. Then, the surface of the wafer
70
is brought into contact with a polishing pad
63
attached to the upper surface of a platen
61
, and polishing is conducted by rotating a wafer polishing head
50
while supplying slurry containing abrasive.
In many cases, the wafer
70
is automatically attached to the lower surface of the polishing head
50
by means of a wafer loading device having a disc-like wafer support portion. At this time, the wafer
70
is accommodated in a wafer cassette, and extracted from the wafer cassette by a wafer extracting mechanism before it is conveyed to the wafer loading device. Then, the wafer
70
is conveyed to a position below the polishing head
50
by the wafer loading device, and the wafer support portion is brought close to the polishing head
50
, whereby the wafer
70
is attached to the polishing head
50
.
When the process for polishing the wafer
70
has been completed and the polishing head
50
is raised so as to be separated from the polishing pad
63
, a wafer unloading device
81
having a disc-like wafer support portion
80
is arranged below the polishing head
50
, as shown in
FIG. 13
, in order to receive the wafer
70
which has undergone the polishing process. Then, the wafer
70
, which has been released from the attraction by the polishing head
50
, is supported on the wafer support portion
80
. The wafer support portion
80
supporting the wafer
70
moves so as to approach a robot arm
82
for conveying the wafer
70
to the next step. A suction mechanism is formed at the forward end
82
a
of the robot arm
82
, and the wafer
70
is held by being sucked by the suction mechanism at the forward end
82
a
, and conveyed to the next step.
When the wafer
70
is attracted by the robot arm
82
, the robot arm
82
first pressurizes the upper surface of the wafer
70
, and stabilizes the surface with which the wafer
70
is attracted by the robot arm
82
. Then, the upper surface of the wafer
70
is attracted by the suction mechanism at the forward end
82
a
of the robot arm
82
, whereby the wafer
70
is held and conveyed to the next step.
When attaching the wafer
70
to the polishing head
50
by using this wafer loading device, the wafer loading device must perform the positioning correctly at the time of attaching the wafer
70
before the wafer
70
can be engaged with the retainer ring
57
in a stable manner. In this process, a high level of machining accuracy is required of each portion of the wafer loading device and high accuracy is required of each drive section.
When transferring the wafer to the robot after detaching the wafer
70
from the polishing head
50
, the robot arm
82
is brought into press contact with the wafer
70
so as to attract the wafer
70
in a stable manner. At this time, a moment acts on the robot arm
82
. However, since the robot arm
82
is in the form of a thin plate, it is subject to bending, so that it is brought into contact with the wafer
70
in an unstable manner. Further, since the robot arm
82
repeats bending, the service life of the robot arm
82
is rather short.
Further, foreign matter such as polishing swarf generated at the time of polishing the wafer adheres to the wafer
70
and the lower side of the polishing head
50
. Due to this foreign matter, there is naturally the danger of the wafer
70
and the polishing head
50
being damaged. Furthermore, when the foreign matter is dried, it sticks to the lower side of the polishing head
50
, etc., so that much effort is needed to perform cleaning.
SUMMARY OF THE INVENTION
The present invention has been made with a view to above problem in the conventional technique. Accordingly, it is an object of the present invention to provide a wafer loading/unloading device which is capable of performing positioning and mounting easily and in a stable manner when attaching the wafer to the polishing head and which can receive the polished wafer in a stable manner and pass it to the next step and a method of producing wafers.
To achieve the above object, there is provided in accordance with the present Invention a wafer loading/unloading device for attaching a wafer to a polishing head and receiving the wafer from the polishing head, comprising a main body portion formed in a circular configuration in plan view and adapted to support a wafer, a swinging arm supporting the main body portion, a swinging shaft for supporting the swinging arm so as to be horizontally swingable, an arm ascending/descending mechanism for supporting the swinging arm so that it can ascend and descend with the main body portion, and a swinging drive source for driving the swinging shaft, wherein the main body portion is equipped with a disc-like wafer support portion and an action force absorbing mechanism for absorbing a vertical force acting on the wafer support portion.
In accordance with the present invention, the wafer support portion is equipped with an action force absorbing mechanism which is a mechanism for absorbing a vertical force acting on the wafer support portion, so that the impact when the wafer is attached to the polishing head is mitigated. Thus, the wafer and the polishing head are prevented from being damaged. Further, when transferring the wafer to the robot after detaching the wafer from the polishing head, if the robot arm presses the wafer downward, the wafer also moves downward due to the action force absorbing mechanism. As a result, the moment acting on the robot arm in the form of a thin plate is reduced, and the forward end portion of the robot arm can be brought into contact with the upper surface of the wafer, with the robot arm not being bent. Thus, the robot arm can reliably hold the wafer, so that the wafer can be passed to the next step in a stable manner.
Further, the wafer support port-on is of a floating construct which is equipped with a swinging mechanism for swingably supporting the wafer support portion. Thus, when attaching he wafer, if the carrier lower surface which is the wafer attachment surface of the polishing head is p
Kaido Yoshie
Kajiwara Jiro
Komasaki Masahito
Banks Derris H.
Mitsubishi Materials Corporation
Wilson Lee
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