Handling: hand and hoist-line implements – Grapple
Reexamination Certificate
1999-12-01
2001-08-14
Kramer, Dean (Department: 2167)
Handling: hand and hoist-line implements
Grapple
C294S001200, C414S941000, C034S058000
Reexamination Certificate
active
06273484
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a substrate holding device. In particular, this invention relates to a wafer holding device provided with a rotatable plate pivoted with jaws to effectively clamp a wafer thereon by means of centrifugal force.
2. Description of Prior Art
Referring to
FIG. 1
, a side view depicts the structure of a wafer W rotated by a wafer holding device
1
to perform the cleaning process according to the prior art.
As shown in
FIG. 1
, the wafer holding device
1
comprises a base
10
, a vacuum pump
12
and a motor M. The base
10
is a supporting plate used to support wafer W and is rotated above an axis A—A by the motor M. A sucking portion
100
formed on the top surface of the base
10
is a concavity communicated to the vacuum pump
12
by a channel
13
. Wafer W is placed on the sucking portion
100
of the base
10
and sucked by the vacuum pump
12
and rotated with the base
10
above the axis A—A. Given the acting force of the flushing water during the cleaning, the contact and suction between the wafer W and the base
10
must be well maintained to prevent disengagement of the wafer W during the rotation.
FIG. 2A
is top view of a wafer holding device
2
according to the second prior art, and
FIG. 2B
is front view showing the structure of the wafer holding device
2
according to FIG.
2
A. As shown in
FIG. 2B
, the holding device
2
of a second example of the prior art comprises a rotatable base
20
, a plurality of pins
21
used to support the wafer W and a motor M used to actuate the base
20
. The pins
21
are spaced apart from each other and mounted on the upper surface of the base
20
, symmetrically and vertically. Each of the pins
21
is provided with a step portion
210
composed of surfaces
211
,
212
and the wafer W is limited and clamped therebetween. The fit and clearance of the wafer W set between the pins
21
should be accurately calculated, otherwise the wafer W easily disengages from the pins
21
when the base
20
is rotated above the axis A—A at a high speed.
SUMMARY OF THE INVENTION
To solve the above problems, the primary object of this invention is to provide a wafer holding device to effectively clamp the wafer while it is rotated during the cleaning process. The wafer holding device of the present invention comprises a base used to rotate about an axis with a predetermined velocity and a plurality of jaws coupled to the base. The jaws are pivotally mounted on the circumference of the base and each is reciprocally moved between a first position and a second position. Each of the jaws has a holding surface for supporting the wafer at the first position as well as clamping the wafer at the second position, wherein the jaws move to the second position by means of centrifugal force generated by the rotation of the base at the predetermined velocity.
REFERENCES:
patent: 4651440 (1987-03-01), Karl
patent: 5851041 (1998-12-01), Anderson et al.
patent: 5954072 (1999-09-01), Matusita
patent: 5974681 (1999-11-01), Gonzalez-Martin
patent: 6167893 (2001-01-01), Taatjes et al.
Beyer Weaver & Thomas LLP
Kramer Dean
Winbond Electronics Corp.
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