US Patent 7097534 Closed-loop control of a chemical mechanical polisher

A method of controlling a chemical mechanical polishing system in which an inner tolerance, an outer tolerance and a specification tolerance limit are received by a control system. The user selects one of the inner tolerance and the outer tolerance, and the user selects a polishing machine procedure for the selected tolerance. A first substrate is polished with the chemical mechanical polishing system, and a thickness of at least one layer in the substrate is measured at an in-line metrology station. If the measured thickness exceeds the selected tolerance, the selected procedure is performed.