Cold liquid polishing control

Abstract

A chemical mechanical polishing apparatus includes 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, a temperature control system including coolant liquid fluid reservoirs for containing coolant fluids, a thermal controller configured to control the temperature of the coolant fluid within the coolant fluid reservoirs, and a first dispenser having openings in fluid connection with the coolant fluid reservoirs, the openings positioned configured to spray an aerosolized coolant liquid directly onto the polishing pad, and a second dispenser having a coolant port in fluid connection with the coolant fluid reservoirs, the coolant port positioned over the platen and configured to flow a stream of coolant liquid directly onto the polishing pad.

What is claimed is: 
     
         1 . A chemical mechanical polishing apparatus 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;   a temperature control system including
 one or more coolant liquid fluid reservoirs for containing one or more coolant fluids, 
 a thermal controller configured to control the temperature of the one or more coolant fluid within the one or more coolant fluid reservoirs; and 
 a first dispenser having a plurality of openings in fluid connection with the one or more coolant fluid reservoirs, the plurality of openings positioned over the platen and configured to spray an aerosolized coolant liquid directly onto the polishing pad, 
 a second dispenser having a coolant port in fluid connection with the one or more coolant fluid reservoirs, the coolant port positioned over the platen and configured to flow a stream of coolant liquid directly onto the polishing pad. 
   
     
     
         2 . The apparatus of  claim 1 , further comprising a temperature control arm extending over the platen, and wherein the one or more openings are formed in nozzles secured to the temperature control arm. 
     
     
         3 . The apparatus of  claim 2 , wherein the coolant port is secured to the temperature control arm. 
     
     
         4 . The apparatus of  claim 2 , wherein the coolant port is secured to a separate temperature control arm. 
     
     
         5 . The apparatus of  claim 4 , comprising a polishing liquid arm extending over the platen, wherein the coolant port and the polishing liquid port are on the polishing liquid arm. 
     
     
         6 . The apparatus of  claim 1 , wherein the thermal controller comprises a temperature sensor and a temperature control element and is configured to receive temperature value from the temperature sensor indicative of a temperature of the coolant fluid and, based on the received temperature value, control the temperature control element to cool the coolant fluid to below 5° C. 
     
     
         7 . The apparatus of  claim 1 , wherein one or more coolant fluid reservoirs include a first coolant fluid reservoir connected to the plurality of openings of the first dispenser and a second coolant fluid reservoir connected to the port of the second dispenser. 
     
     
         8 . The apparatus of  claim 7 , wherein the second coolant fluid reservoir is configured to hold less coolant fluid than the first coolant fluid reservoir. 
     
     
         9 . The apparatus of  claim 7 , wherein the first coolant fluid reservoir and the second coolant fluid reservoir hold a same composition of coolant liquid. 
     
     
         10 . The apparatus of  claim 9 , wherein the coolant liquid is deionized water. 
     
     
         11 . The apparatus of  claim 7 , wherein the temperature control system is configured to control both the first coolant fluid reservoir and the second coolant fluid reservoir to different temperature values, the temperature value of the second coolant fluid reservoir being lower than the temperature value of the first coolant fluid reservoir. 
     
     
         12 . The apparatus of  claim 1 , wherein one or more coolant fluid reservoirs include a common coolant fluid reservoir connected to the plurality of openings of the first dispenser and to the port of the second dispenser. 
     
     
         13 . The apparatus of  claim 1 , wherein the temperature control system is configured to dispense less than 1 L of fluid through the second dispenser to reduce a temperature of the polishing pad by at least 10° C. 
     
     
         14 . The apparatus of  claim 1 , further comprising a controller configured to cause the first dispenser to spray the aerosolized coolant liquid onto the polishing pad during a polishing step in which the substrate is polished on the polishing pad, and to cause the second dispenser to flow the stream of coolant fluid onto the polishing pad at a transition from a first polishing step to a second polishing step. 
     
     
         15 . The apparatus of  claim 14 , wherein the controller is configured to receive a temperature measurement from a sensor during the polishing step and to control the first dispenser to spray the aerosolized coolant liquid so as to bring the measured temperature to a desired temperature. 
     
     
         16 . The apparatus of  claim 14 , wherein the controller is configured to receive a signal indicating that less than a threshold amount of material remains to be polished, and to control the second dispenser to flow the stream of coolant fluid onto the polishing pad in response to the signal. 
     
     
         17 . The apparatus of  claim 1 , further comprising a pad rinse system including a nozzle to direct a rinsing medium onto the polishing pad. 
     
     
         18 . 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. 
   
     
     
         19 . 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.   
     
     
         20 . The method of  claim 19 , further comprising controlling the temperature of the cooling liquid during the polishing process to be less than 5° C.