Chemical mechanical polishing temperature scanning apparatus for temperature control

A chemical mechanical polishing apparatus comprising:

• a rotatable platen having an axis of rotation and a top surface to hold a polishing pad;
• a carrier head to hold a substrate against a polishing surface of the polishing pad during a polishing process;
• a temperature control system including a heater and/or cooler,
• a support extending over the platen,
• a temperature monitoring system including a non-contact thermal sensor positioned above the platen to have a field of view of a portion of the polishing pad on the platen;
• an actuator to move the sensor radially relative to the axis of rotation;
• a controller coupled to the temperature control system, the temperature monitoring system and the linear actuator and configured to
• control the actuator so as to cause the thermal sensor to move radially relative to the axis of rotation,
• receive a plurality of temperature measurements from thermal sensor of the polishing pad at a plurality of different radial distances from the axis of rotation of the platen,
• determine radial positions of the field of view of the thermal sensor relative to the axis of rotation of the platen for the plurality of temperature measurements,
• generate a radial temperature profile of the polishing pad using the plurality of temperature measurements and the radial positions, and
• adjust operation of the heater and/or cooler based on the radial temperature profile so as to improve temperature uniformity of the polishing pad.