Abrading – Work feeder – Ejector or unloader
Reexamination Certificate
1999-04-22
2001-03-06
Banks, Derris H. (Department: 3723)
Abrading
Work feeder
Ejector or unloader
C451S397000
Reexamination Certificate
active
06196906
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to measures for taking out a workpiece from a surface plate after completion of polishing in a surface polishing device for polishing a disc-like workpiece such as a semiconductor wafer or a magnetic disc substrate.
RELATED ART
A surface polishing apparatus such as a lapping machine or a polishing machine, incorporates a sun gear, an internal gear and upper and lower surface plates which are concentrically arranged, and a carry meshed with both gears so as to carries out planetary motion. With this arrangement, opposite surfaces of a workpiece W held by the carrier by means of the surface plates are polished while polishing liquid is fed thereto.
In such a polishing apparatus, the workpiece after completion of polishing is taken out by, for example, a vacuum type chuck means from a holding hole for the workpiece in the carrier. Since washing liquid is present between the workpiece and the outer surfaces of the surface plates, the workpiece sticks to the outer surfaces of the surface plates due to the surface tension of the polishing liquid, and accordingly, a large force is required for taking out the workpiece or it is likely to cause damage such as breakage to the workpiece. In particular, such damage is liable to occur to a thin workpiece such as a semiconductor wafer.
SUMMARY OF THE INVENTION
An object of the present invention is to enable a workpiece to be simply and surely taken out from a surface plate even though polishing liquid is present therebetween.
To that end according to the present invention, there is provided a method of taking out a workpiece, comprising the steps of chucking a workpiece horizontally set on a surface plate by means of a chuck means, lifting up one end of the workpiece by inclining the chuck mechanism with the use of a posture control mechanism so as to separate the workpiece from the surface plate, and thereafter, lifting the workpiece in its entirety so as to take out the workpiece from the surface plate.
In the above-mentioned method, the above-mentioned workpiece may be chucked mechanically at its outer periphery by a plurality of openable pawl members or under vacuum.
Further, in order to carry out the above-mentioned take-out method, according to the present invention, there is provided a takeout apparatus comprising a chuck means for chucking a workpiece, and a posture control device for controlling the posture of the workpiece. The chuck means has a plurality of pawl members which can be opened and closed by a first actuator attached to a base member, and with which a workpiece is chucked at its outer periphery. Further, the above-mentioned posture control mechanism has a support part provided at the distal end of a takeout arm, for supporting the base member which is therefore tiltable, and a second actuator for controlling the posture of the base member between a horizontal condition and an inclined condition, and accordingly, the chuck means is inclined by the second actuator through the intermediary of the base member. The above-mentioned carrier has a plurality of cutouts at the peripheral edge of the workpiece holding hole, through which the pawl members of the chuck means are inserted and engaged with the outer periphery of the workpiece.
In a surface polishing apparatus according to the present invention, instead of the above-mentioned chuck means for chucking the outer periphery of the workpiece by means of the pawl members, a vacuum chuck means comprising a chuck head having suction holes connected to a vacuum pump, and a base member for supporting the chuck head can be used.
In a specific form of the present invention, the base member of the chuck means is suspended by the support member at a position where the base member is gravitationally unbalanced, and accordingly, the chuck means is inclined by its dead weight when the takeout arm is lifted. Further, it is returned to its horizontal posture by means of the second actuator.
According to the present invention having the above-mentioned arrangement, the workpiece is not lifted up being held horizontally, but it is lifted up at first by its one end so as to be separated from the surface plate, and thereafter, the workpiece is lifted up its entirety so as to be taken out. Thus, even though the workpiece is stuck to the outer surface of the surface plate by the polishing liquid which is present between the workpiece and the surface plate, the sticking can be simply eliminated, and accordingly, the workpiece can surely be taken out by a small force. Thereby it is possible to safely take out the workpiece with no damage even though the workpiece such as a semiconductor wafer has a thin thickness and a large diameter.
REFERENCES:
patent: 4502252 (1985-03-01), Iwabuchi
patent: 5333413 (1994-08-01), Hashimoto
patent: 5429544 (1995-07-01), Hasegawa et al.
patent: 5443416 (1995-08-01), Volodarsky et al.
patent: 5947802 (1999-09-01), Zhang et al.
Banks Derris H.
Snell & Wilmer L.L.P.
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