Material or article handling – Article reorienting device – Orienter has article gripping means
Reexamination Certificate
1999-04-15
2002-01-22
Krizek, Janice L. (Department: 3652)
Material or article handling
Article reorienting device
Orienter has article gripping means
C414S936000
Reexamination Certificate
active
06340281
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method and an apparatus for positioning a disk-shaped object in a predetermined position and orientation.
BACKGROUND OF THE INVENTION
For example, a reaction chamber is used to form an electrode pattern on the surface of a semiconductor wafer by plasma dry etching. This processing operation is a minute and delicate one, in which a wafer is held on an electrode in a reaction chamber, for example, by electrostatic attraction, vacuum is produced in the reaction chamber and plasma gas is generated, and heat transfer gas such as He gas is supplied onto the back surface of the wafer facing the electrode to keep the temperature, by which the operation is performed. In order to achieve such an operation with required accuracy, the wafer must be placed on the electrode with high positional accuracy. In many cases, since the wafer has a disk shape, the position of its center becomes a problem. Also, since the wafer is a single crystal, the electrode pattern or the like must be formed corresponding to the orientation of the crystal. Therefore, the positioning necessary for the aforesaid operation must be performed with regard to the position of the wafer center and the orientation around the center.
To position such a disk-shaped object with regard to the center position and orientation thereof, a notch b, which is an orientation flat (straight cut portion) or a notch indicating the orientation of a disk-shaped object a, is formed at the outer periphery of the disk-shaped object a as shown in FIG.
6
. After this disk-shaped object a is placed on a rotating stage c, the rotating stage c is moved together with a rotating mechanism d in two directions of X and Y perpendicular to each other by using an X-direction moving table e and a Y-direction moving table f, by which the center position of the disk-shaped object a is positioned at a predetermined position. To orient this disk-shaped object a, whose center has been positioned, around the center thereof, the rotating stage c is turned by the rotating mechanism d such as a motor so that the notch b formed in the disk-shaped object a is oriented in a predetermined direction. In positioning, the center position of the disk-shaped object a is judged by detecting about three points of outer periphery of the disk-shaped object a by using a range-finding sensor g, and the rotating stage c is moved so that the judged center position becomes the predetermined position. The orientation of the disk-shaped object a, whose center has been positioned, is judged by detecting the direction of the notch b by using the range-finding sensor g, and the rotating stage c is turned so that the detected direction becomes the predetermined direction. The above described positioning mechanism is usually formed into a unit. In positioning in the atmosphere, this unit is arranged in an air flow of down flow, and a mechanism portion h is located under the disk-shaped object a to prevent dust produced by the mechanism portion h from flying up, by which dust is prevented from affecting the delicate processing operation, and the quality is prevented from being degraded.
When a vacuum vessel i communicating with the reaction chamber, as shown in
FIG. 7
, is used, the mechanism portion h is arranged under the vacuum vessel i, and the rotating stage c is located in the vacuum vessel i from the downside. In this case, it is necessary to seal a portion that a rotating shaft j of the rotating stage c passes through to prevent leakage when a vacuum is produced in the reaction chamber. For this purpose, a portion of the vacuum vessel i that the rotating shaft j passes through is covered with bellows k. Specifically, one end of the bellows k is connected to the circumference of the opening of the vacuum vessel i that the rotating shaft j passes through, and a vacuum seal m connected to the other end of the bellows k and the rotating shaft j are in slidable contact with each other while maintaining airtightness. Thereupon, the aforementioned necessary positioning can be performed by turning the rotating shaft j and moving it in the direction perpendicular to the axis thereof without the occurrence of leakage under vacuum.
However, in the conventional sealing construction using the bellows k as shown in
FIG. 7
, which is used for positioning in the vacuum vessel, the slidable contact portion between the vacuum seal m and the rotating shaft j is located in the vacuum region, so that dust produced here adheres to the wafer, resulting in the adverse effect of dust on the delicate processing operation and the degraded quality. Also, such a sliding portion is liable to be damaged and has a low physical life. If any trouble occurs, a vacuum break is caused, and the reliability as the wafer positioning mechanism is decreased. Further, the bellows k must have rigidity for overcoming a restoring force such as to be straightened by the vacuum in the direction such that the misalignment relative to the rotating shaft is eliminated and a deformation caused when following the movement in the direction perpendicular to the axis for the positioning of the rotating shaft j. This following action of the bellows k causes a load when the rotating stage c is moved in the direction perpendicular to the axis to perform the positioning, so that a design is required such as to satisfy the positioning rigidity requirement for overcoming this load, resulting in increased weight and size of the apparatus and therefore an increased cost. An object of the present invention is to provide a method and an apparatus for positioning a disk-shaped object, in which the life of a sealing portion is prolonged by using bellows, and the generation of dust and the effect thereof are prevented.
SUMMARY OF THE INVENTION
To attain the above object, with the method for positioning the disk-shaped object in accordance with the present invention, to position the disk-shaped object by supporting a disk-shaped object by a support member which can be rotated and moved in the direction perpendicular to the axis of the rotation, and by moving the support member from the outside of a vacuum vessel, the support member is extended to the outside of the vacuum vessel through an opening of the vacuum vessel and bellows one end of which is connected to the circumference of the opening without being in contact with the opening and the bellows and with a play such that the aforesaid movement can be performed, and the support member is received in a bulkhead portion by a roller bearing so as to be capable of rotating as described above, said bulkhead portion connected to the other end of the bellows and closing the other end of the bellows of a bearing support. The leakage under vacuum can be prevented by sealing the opening of the vacuum vessel that the support member passes through by using the bellows and the bulkhead of the support member, and at the same time the support member can be supported so as to be capable of rotating by eliminating a sliding portion located in the vacuum region by using the bulkhead and the roller bearing at the sealing portion, so that the decrease in life of the sealing portion caused by the sliding portion, the generation of dust, and the adhesion of dust to the object being positioned can be avoided.
Moreover, since necessary rotation is given to the support member from the outside of the bulkhead of the support member via a pair of inside and outside magnetic couplings facing each other on the inside and outside of the bulkhead in a state in which the play is present between the support member and the bellows, and movement in the direction perpendicular to the axis is given to the support member by moving the support member from outside in the direction perpendicular to the axis with respect to the vacuum vessel, the movement necessary for positioning is achieved while the sealing state and the non-contact state between the support member and the bellows are maintained, by which the positioning of the disk-shaped object can be performed.
By opti
Haraguchi Hideo
Matsuda Izuru
Krizek Janice L.
Matsushita Electric - Industrial Co., Ltd.
Parkhurst & Wendel L.L.P.
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