Slurry-based temperature control for cmp

Abstract

A method for removing material from a substrate includes dispensing an abrasive slurry on a polishing pad, storing an indication of a relative charge on the abrasive agent, contacting a surface of a substrate to the polishing pad in the presence of the slurry, generating relative motion between the substrate and the polishing pad, measuring a removal rate for the substrate, comparing a the measured removal rate to a target removal rate and determining whether to increase or decrease the removal rate based on the comparison, determining whether to increase or decrease a temperature of an interface between the polishing pad and the substrate based on the indication of the relative charge of the abrasive agent and on whether to increase or decrease the removal rate, and controlling a temperature of the interface as determined to modify the removal rate.

What is claimed is: 
     
         1 . A method of polishing, comprising:
 dispensing a polishing slurry containing negatively charged ceria oxide onto a polishing pad;   contacting a surface of a substrate to the polishing pad in the presence of the slurry;   generating relative motion between the substrate and the polishing pad to polish the surface of the substrate;   measuring at a removal rate for the substrate;   determining that the measured removal rate is less than a target removal rate; and   in response to determining that the measured removal rate is less than the target removal rate, decreasing a temperature of an interface between the polishing pad and the substrate.   
     
     
         2 . The method of  claim 1 , wherein decreasing the temperature comprises dispensing a coolant fluid onto the polishing pad. 
     
     
         3 . The method of  claim 2 , wherein the coolant fluid is DI water chilled below 20° C. 
     
     
         4 . The method of  claim 2 , wherein dispensing the coolant fluid comprises spraying the coolant fluid through a convergent-divergent nozzle. 
     
     
         5 . The method of  claim 1 , wherein measuring the removal rate comprises monitoring the substrate during polishing with an in-situ optical monitoring system. 
     
     
         6 . The method of  claim 1 , wherein the surface of the substrate comprises an oxide layer. 
     
     
         7 . The method of  claim 6 , wherein the oxide layer comprises silicon oxide. 
     
     
         8 . A method of polishing, comprising:
 dispensing a polishing slurry containing negatively charged ceria oxide onto a polishing pad;   contacting a surface of a substrate to the polishing pad in the presence of the slurry;   generating relative motion between the substrate and the polishing pad to polish the surface of the substrate;   measuring at a removal rate for the substrate;   determining that the measured removal rate is greater than a target removal rate; and   in response to determining that the measured removal rate is greater than the target removal rate, increasing a temperature of an interface between the polishing pad and the substrate.   
     
     
         9 . The method of  claim 8 , wherein increasing the temperature comprises dispensing a heating fluid onto the polishing pad. 
     
     
         10 . The method of  claim 9 , wherein dispensing the heating fluid comprises spraying the heating fluid. 
     
     
         11 . The method of  claim 9 , wherein the heating fluid comprises steam. 
     
     
         12 . The method of  claim 8 , wherein measuring the removal rate comprises monitoring the substrate during polishing with an in-situ optical monitoring system. 
     
     
         13 . The method of  claim 6 , wherein the surface of the substrate comprises an oxide layer. 
     
     
         14 . The method of  claim 13 , wherein the oxide layer comprises silicon oxide. 
     
     
         15 . A method for removing material from a substrate, comprising:
 dispensing a slurry on a surface of a polishing pad, wherein the slurry includes a carrier liquid and an abrasive agent;   storing an indication of a relative charge on the abrasive agent;   contacting a surface of a substrate to the polishing pad in the presence of the slurry;   generating relative motion between the substrate and the polishing pad to polish the surface of the substrate;   measuring a removal rate for the substrate;   comparing a the measured removal rate to a target removal rate and determining whether to increase or decrease the removal rate based on the comparison;   determining whether to increase or decrease a temperature of an interface between the polishing pad and the substrate based on the indication of the relative charge of the abrasive agent and on whether to increase or decrease the removal rate; and   controlling a temperature of the interface as determined to modify the removal rate.   
     
     
         16 . The method of  claim 15 , wherein the abrasive agent comprises cerium oxide particles. 
     
     
         17 . The method of  claim 15 , wherein controlling the temperature of the removal medium includes increasing the polishing rate by increasing the temperature if the indication is positively charged, increasing the polishing rate by decreasing the temperature if the indication is negatively charged, decreasing the polishing rate by decreasing the temperature if the indication is positively charged, or decreasing the polishing rate by increasing the temperature if the indication is negatively charged. 
     
     
         18 . A computer program product, comprising instructions on non-transitory computer readable media, to cause one or more computers to:
 cause a polishing system to polish a substrate on a polishing pad using a slurry with an abrasive agent;   store an indication of a relative charge on the abrasive agent;   calculate a removal rate for the substrate based on a signal received from an in-situ monitoring system;   compare the measured removal rate to a target removal rate;   determine whether to increase or decrease the removal rate based on the comparison;   determine whether to increase or decrease a temperature of an interface between the polishing pad and the substrate based on the indication of the relative charge on the abrasive agent and on whether to increase or decrease the removal rate; and   cause a temperature control system to adjust a temperature of the interface as determined to modify the removal rate.   
     
     
         19 . The computer program product of  claim 18 , wherein the instructions to control the temperature of the removal medium include instructions to increase the polishing rate by increasing the temperature if the indication is positively charged, and instructions to increase the polishing rate by decreasing the temperature if the indication is negatively charged. 
     
     
         20 . The computer program product of  claim 18 , wherein the instructions to control the temperature of the removal medium include instructions to decrease the polishing rate by decreasing the temperature if the indication is positively charged, and instructions to decrease the polishing rate by increasing the temperature if the indication is negatively charged.