METHOD FOR PREVENTING DAMAGE TO WAFERS IN A SEQUENTIAL MULTIPLE STEPS POLISHING PROCESS

摘要

A method for preventing the drying of a residue on a wafer surface in a multiple stage polishing operation increases wafer processing throughput and extends the useful life of polishing pads used in a CMP operation. The method includes detecting a polishing endpoint for a wafer polished in a second polishing step following a first polishing operation for the wafer. Endpoint detection terminates polishing of another wafer in the first polishing operation and triggers overpolishing of the prior wafer in the second polishing operation. After a set period, overpolishing of the prior wafer in the second polishing operation ends. Finally each of the wafers moves to a subsequent processing operation, which may include a polishing operation or a buffing operation. One of the advantages of the invention is the maximization of total platen pad usage between platen pad changes since total processing time has been increased for the same polishing pads, thus permitting polishing of greater numbers of wafers between platen pad changes.