Cold liquid polishing control

A chemical mechanical polishing system comprising:

• two polishing stations, each station comprising
• a platen to hold a polishing pad,
• a carrier to hold a substrate against a polishing surface of the polishing pad during a polishing process,
• a polishing liquid dispenser having a polishing liquid port positioned over the platen to deliver polishing liquid onto the polishing pad, and
• a coolant dispenser having a coolant port positioned over the platen to deliver coolant liquid onto the polishing pad;
• and
• a temperature control system comprising
• a coolant fluid reservoir for containing coolant fluid and configured to deliver the coolant fluid to the respective coolant ports of the respective polishing stations, and
• a thermal controller configured to control the temperature of the coolant fluid within the coolant fluid reservoir.

A method for controlling a chemical mechanical polishing process, comprising:

• polishing a substrate on a surface of a polishing pad in a polishing process comprising at least a bulk removal step and a clearing step;
• determining a desired temperature for the bulk removal step;
• during the bulk removal step, spraying the polishing pad with a cooling liquid to bring the polishing pad to the desired temperature;
• detecting a transition from the bulk removal step to the clearing step;
• and
• in response to detecting the transition from the bulk removal step to the clearing step dispensing, flowing the cooling liquid onto the surface to reduce a temperature of the polishing pad.