Methods and apparatus for feedback controlled polishing. A computer program
product for generating feedback for chemical mechanical polishing. The product
includes instructions operable to cause a processor to receive monitoring information
during a current polishing cycle in which a first polishing process is performed
on a substrate that includes a metal layer. The first polishing process clears
the metal layer from the substrate during the current polishing cycle. The product
includes instructions to calculate a representation of a clearing profile of the
first polishing process. The calculation is based on the monitoring information
received during the current polishing cycle. The product includes instructions
to detect non-uniformity in the representation. The product includes instructions
to generate, from the non-uniformity detected, feedback information for improving
the uniformity of a clearing profile of the first polishing process for a subsequent
polishing cycle.