Real time profile control for chemical mechanical polishing

A method of controlling processing of a substrate, comprising:

• generating, based on a signal from an in-situ monitoring system, a first sequence of characterizing values indicative of a physical property of a reference zone on a substrate undergoing processing and being monitored by the in-situ monitoring system;
• generating, based on the signal from the in-situ monitoring system, a second sequence of characterizing values indicative of a physical property of a control zone on the substrate;
• determining a reference zone rate from the first sequence of characterizing values;
• determining a control zone rate from the second sequence of characterizing values;
• determining an error value by comparing a characterizing value for the reference zone to a characterizing value for the control zone;
• calculating, using a proportional-integral-derivative control algorithm, an output parameter value for the control zone in a first control loop based on at least i) the error value and ii) a dynamic nominal control zone value;
• generating the dynamic nominal control zone value in a second control loop based on at least the reference zone rate and the control zone rate;
• and
• processing the substrate, including processing the control zone of the substrate according to the output parameter value.

A polishing system, comprising:

• a platen to hold a polishing pad;
• a carrier to hold a substrate in contact with the polishing pad;
• a motor coupled to at least one of the platen and the carrier to create relative motion therebetween;
• an in-situ monitoring system configured to generate a signal indicative of a physical property of the substrate during polishing of the substrate;
• and
• a controller to receive the signal and configured to
• generate, based on the signal from the in-situ monitoring system, a first sequence of characterizing values indicative of the physical property of a reference zone on the substrate;
• generate, based on the signal from the in-situ monitoring system, a second sequence of characterizing values indicative of the physical property of a control zone on the substrate;
• determine a reference zone rate from the first sequence of characterizing values;
• determine a control zone rate from the second sequence of characterizing values;
• determine an error value by comparing a characterizing value for the reference zone to a characterizing value for the control zone;
• calculate, using a proportional-integral-derivative control algorithm, an output pressure value for the control zone in a first control loop based on at least i) the error value and ii) a dynamic nominal control zone value;
• generate the dynamic nominal control zone value in a second control loop based on at least the reference zone rate and the control zone rate;
• and
• cause the carrier to apply the output pressure value to the control zone of the substrate.