Endpoint detection apparatus and method for chemical/mechanical polishing
First Claim
1. In a process of polishing of a layer of a first material requiring a chemical/mechanical removal process arranged over a layer of second material requiring only a mechanical removal process disposed on a surface of a workpiece wherein the workpiece is rotated by a first motor and is brought into contact with a polish wheel rotated by a second motor and having a polishing pad disposed thereon, the improvement comprising:
- providing a chemical/mechanical slurry on said polishing pad wherein said polishing pad is coated with said slurry;
placing the workpiece on the polishing pad and rotating the workpiece and the polishing pad,maintaining the rotational speed of the workpiece above the rotational speed of the polish wheel and applying pressure to the workpiece and;
monitoring the current drawn by the first motor.
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Accused Products
Abstract
An apparatus and method for determining a selected endpoint in the polishing of layers on a workpiece in a chemical/mechanical polishing apparatus where the workpiece is rotated by a motor against a polishing pad. When a difficult to polish layer, i.e., one requiring a chemical change in a surface skin of the layer which skin is then abraded away by a mechanical process is removed from a more easy to polish surface, i.e., one that relies solely on mechanical abrasion and does not need to have a chemically converted skin thereon. The power required to maintain a set rotational speed in a motor rotating the workpiece significantly drops when the difficult to polish layer is removed. This current drop is used to detect the point at which the polishing must be stopped to avoid over polishing effects, i.e., dishing or thinning or removal of the more easily removed underlying material. Thus, an end point in the process can be established.
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Citations
14 Claims
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1. In a process of polishing of a layer of a first material requiring a chemical/mechanical removal process arranged over a layer of second material requiring only a mechanical removal process disposed on a surface of a workpiece wherein the workpiece is rotated by a first motor and is brought into contact with a polish wheel rotated by a second motor and having a polishing pad disposed thereon, the improvement comprising:
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providing a chemical/mechanical slurry on said polishing pad wherein said polishing pad is coated with said slurry; placing the workpiece on the polishing pad and rotating the workpiece and the polishing pad, maintaining the rotational speed of the workpiece above the rotational speed of the polish wheel and applying pressure to the workpiece and; monitoring the current drawn by the first motor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A process for polishing a workpiece wherein said workpiece comprises a first material having a first coefficient of friction arranged over a second material having a second coefficient of friction wherein said first coefficient is higher than said second coefficient, comprising,
holding said workpiece in contact with a polishing pad disposed on a polishing wheel; -
providing a slurry on said polishing pad; rotating said workpiece by a first motor; rotating said polishing wheel by a second motor wherein rotational speed of said workpiece is above rotational speed of said polishing wheel; monitoring current in said first motor; detecting an endpoint in said polishing after current in said first motor is reduced.
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Specification