Endpoint detection apparatus and method for chemical/mechanical polishing
US5308438A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 30, 1992 |
| Grant date | May 3, 1994 |
| Priority date | — |
| Expiry date | Jan 30, 2012 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01L21/31053
- WIPO fieldMachine tools
- WIPO sectorMechanical engineering
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.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.