Feedback controlled polishing processes

A method for generating feedback for chemical mechanical polishing, the method comprising:

• receiving monitoring information during a second polishing process of a first polishing cycle which includes a first polishing process and the second polishing process performed on a first substrate that includes a metal layer, the monitoring information including information for two or more sampling regions that correspond to different annular regions of the substrate, the first polishing process removing a portion of the metal layer, the second polishing process clearing the metal layer from the first substrate during the first polishing cycle;
• calculating, for each sampling region, a clearing time of the second polishing process, the calculation being based on the monitoring information received;
• detecting non-uniformity in the calculated clearing times;
• generating, from the non-uniformity detected, feedback information for improving the uniformity of a clearing profile;
• and
• adjusting the first polishing process in a subsequent polishing cycle of a subsequent substrate, the adjustment being based on the feedback information.