The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 03, 1994
Filed:
Jan. 30, 1992
William J Cote, Poughquag, NY (US);
John E Cronin, Milton, VT (US);
William R Hill, Underhill, VT (US);
Cheryl A Hoffman, Colchester, VT (US);
International Business Machines Corporation, Armonk, NY (US);
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.