Polishing a workpiece using equal velocity at all points overlapping a polisher
First Claim
1. A polishing machine for polishing a surface of a workpiece, said polishing machine comprising:
- a workpiece holder rotatable about a first axis, said workpiece holder being capable of holding said workpiece, wherein during rotary motion of said workpiece holder with said workpiece held thereon, said workpiece rotates at a first angular velocity about said first axis;
a workpiece polisher rotatable about a second axis, said second axis being parallel to said first axis and laterally displaced therefrom such that when viewed in a direction parallel to one of said axes, a portion of a left side of said workpiece polisher overlaps a portion of a right side of said workpiece holder thereby to cause all points of said workpiece in said overlap area to have substantially equal relative velocity with respect to said workpiece polisher when said workpiece polisher rotates at approximately the same angular velocity as said workpiece; and
means for forcing said workpiece polisher and said workpiece towards each other and for causing said workpiece surface to be polished during passage of said workpiece through said overlap area.
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Accused Products
Abstract
A polishing machine for polishing a single side (e.g. a circuit side) of a workpiece (e.g. a semiconductor wafer) includes two platens. A first platen can be a workpiece-holding platen having slots or other structure for holding wafers or other workpieces. The second platen is a polishing platen and is covered with a polishing pad or other material used for polishing, e.g. glass or metal polishing. The two platens have laterally spaced axes of rotation such that, from a top view, the right side of one platen overlaps the left side of the other platen or vice versa. The two platens are both rotated at the same angular velocity i.e. at the same revolutions per minute (RPM) and both clockwise or both counterclockwise, and the two platens overlap such that the differences in velocity (i.e., relative velocity) between overlapping points on the two platens across a workpiece held on the first platen is constant. A second embodiment of the polishing machine uses one or more polishing rollers, instead of the polishing platen described above. In the second embodiment as well, a uniform relative velocity is obtained at overlapping points on the two platens across the workpiece when the angular velocity of the workpiece-holding platen is equal to the angular velocity of the polishing roller about a lateral axis perpendicular to the longitudinal axis of the polishing roller. The polishing roller is simultaneously rotated about the longitudinal axis (which is perpendicular to the lateral axis) to increase or decrease the uniform relative velocity with which the workpiece is polished.
259 Citations
31 Claims
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1. A polishing machine for polishing a surface of a workpiece, said polishing machine comprising:
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a workpiece holder rotatable about a first axis, said workpiece holder being capable of holding said workpiece, wherein during rotary motion of said workpiece holder with said workpiece held thereon, said workpiece rotates at a first angular velocity about said first axis; a workpiece polisher rotatable about a second axis, said second axis being parallel to said first axis and laterally displaced therefrom such that when viewed in a direction parallel to one of said axes, a portion of a left side of said workpiece polisher overlaps a portion of a right side of said workpiece holder thereby to cause all points of said workpiece in said overlap area to have substantially equal relative velocity with respect to said workpiece polisher when said workpiece polisher rotates at approximately the same angular velocity as said workpiece; and means for forcing said workpiece polisher and said workpiece towards each other and for causing said workpiece surface to be polished during passage of said workpiece through said overlap area. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. An apparatus for polishing a surface of a workpiece, said apparatus comprising:
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a first structure capable of holding a workpiece, said first structure being rotatable about a first center such that a first peripheral point of said first structure defines a first circle during rotary motion of said first structure; a second structure capable of holding a polishing pad, said second structure being rotatable about a second center such that a second peripheral point of said second structure defines a second circle during rotary motion of said second structure, wherein said first circle overlaps said second circle to form an overlap area located only between a first straight line passing through said first center and a second straight line passing through said second center, said first straight line and said second straight line being parallel to each other and both lines being perpendicular to a center straight line passing through said first center and said second center; and means for forcing said workpiece and said polisher toward each other in a direction parallel to the first straight line, and for causing said workpiece surface to be polished uniformly at all points during contact with said polisher. - View Dependent Claims (12, 13, 14)
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15. An apparatus for polishing a workpiece, said apparatus comprising:
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first means rotatable about a first center, said first means being capable of holding said workpiece; second means rotatable about a second center removed from said first center, said second means being capable of holding a polisher for polishing said workpiece, a portion of said first means overlapping a portion of said second means in an overlap area such that on rotation of each of said first means and said second means at the same angular velocity, the relative velocity between said polisher and said workpiece is substantially uniform at all points of said workpiece in said overlap area. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22)
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23. A method for polishing a workpiece, said method comprising the steps of:
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mounting a workpiece holder at a first point and a workpiece polisher at a second point removed from said first point; and rotating each of said workpiece holder and said workpiece polisher at approximately the same angular velocity such that the relative velocity across a workpiece held by said workpiece holder is substantially uniform at each point of said workpiece overlapping said workpiece polisher. - View Dependent Claims (24, 25, 26, 27)
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28. A polishing machine for polishing a surface of a workpiece, said polishing machine comprising:
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a workpiece holder rotatable about a first axis, said workpiece holder being capable of holding said workpiece, wherein during rotary motion of said workpiece holder with said workpiece held thereon, said workpiece rotates at a first angular velocity about said first axis; a workpiece polisher rotatable about a second axis, said second axis being parallel to said first axis and laterally displaced therefrom such that when viewed in a direction parallel to one of said axes, a portion of a right side of said workpiece polisher overlaps a portion of a left side of said workpiece holder thereby to cause all points of said workpiece in said overlap area to have substantially equal relative velocity with respect to said workpiece polisher when said workpiece polisher rotates at approximately the same angular velocity as said workpiece; and means for forcing said workpiece polisher and said workpiece towards each other and for causing said workpiece surface to be polished during passage of said workpiece through said overlap area. - View Dependent Claims (29, 30, 31)
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Specification