Cleaning of cmp temperature control system

Abstract

A chemical mechanical polishing apparatus has a heating system, a purge gas source, a purge liquid source, and a controller. The heating system includes a source of heated gas, an arm extending over a platen, and a manifold in the arm with an a plurality of openings positioned over the platen and separated from a polishing pad for delivering the heated gas onto the polishing pad. The controller is configured to cause the heated gas to flow from the source of heated gas through the manifold and the plurality of openings to heat the polishing pad during a polishing operation, and to cause the apparatus to perform a purging operation which alternates between flowing purge gas from the purge gas source and flowing purge liquid from the purge liquid source through the manifold and the plurality of openings.

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; and   a heating system including a source of heated gas, an arm extending over the platen, and a manifold with an a plurality of openings positioned over the platen and separated from the polishing pad for delivering the heated gas onto the polishing pad;   a purge gas source;   a purge liquid source; and   a controller configured to cause the heated gas to flow from the source of heated gas through the manifold and the plurality of openings to heat the polishing pad during a polishing operation, and to cause the apparatus to perform a first purging operation which alternates between flowing purge gas from the purge gas source and flowing purge liquid from the purge liquid source through the manifold and the plurality of openings.   
     
     
         2 . The apparatus of  claim 1 , wherein the controller is configured to iterate flowing the purge gas and flowing purge liquid for two to ten iterations. 
     
     
         3 . The apparatus of  claim 2 , wherein the controller is configured to, for each iteration, cause the purge gas to flow for five to twenty seconds. 
     
     
         4 . The apparatus of  claim 2 , wherein the controller is configured to, for each iteration, cause the purge liquid to flow for five to twenty seconds. 
     
     
         5 . The apparatus of  claim 1 , comprising a common fluid delivery line coupling the source of heated gas and the purge gas source to the manifold. 
     
     
         6 . The apparatus of  claim 5 , wherein the source of heated gas comprises a boiler, the boiler having an inlet for a heating liquid source, a drain, and a steam outlet coupled to the common fluid delivery line. 
     
     
         7 . The apparatus of  claim 6 , wherein the purge liquid source serves as a heating liquid source coupled to the boiler. 
     
     
         8 . The apparatus of  claim 7 , wherein the controller is configured to cause the purge liquid to flow from the purge liquid source by causing the boiler to fill with the purge liquid until the purge liquid flows through the steam outlet. 
     
     
         9 . The apparatus of  claim 8 , wherein the controller is configured to cause the purge liquid to drain from the boiler. 
     
     
         10 . The apparatus of  claim 5 , wherein the controller is configured to cause the apparatus to perform a second purging operation which alternates between alternately filling and draining the boiler. 
     
     
         11 . The apparatus of  claim 10 , wherein the controller is configured to cause filling and draining of the boiler to be performed iteratively while a heating element of the boiler is disabled. 
     
     
         12 . The apparatus of  claim 10 , wherein the controller is configured to iterate draining and filling the boiler two to ten times. 
     
     
         13 . The apparatus of  claim 11 , comprising the heated liquid source, and wherein the heated liquid source is a water source such that the heated gas comprises steam. 
     
     
         14 . 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 heating system including
 an arm extending over the platen, the arm having a manifold with a plurality of openings positioned over the platen and separated from the polishing pad for delivering the heated gas onto the polishing pad, 
 a source of heating liquid, 
 a boiler having an inlet for the heating liquid and a steam outlet coupled by a fluid delivery line to the manifold in the arm; and 
   a controller configured to cause the heated gas to flow from the boiler through the manifold and the plurality of openings to heat the polishing pad during a polishing operation, and to cause the apparatus to perform a purging operation which alternates between filling and draining the boiler with the heating liquid.   
     
     
         15 . The apparatus of  claim 14 , wherein the controller is configured to cause filling and draining of the boiler to be performed iteratively while a heating element of the boiler is disabled. 
     
     
         16 . The apparatus of  claim 15 , wherein the controller is configured to iterate draining and filling the boiler two to ten times. 
     
     
         17 . 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 source of heated gas; and   an arm extending over the platen, the arm including a diffusion plate that separates a volume inside the arm into an upper plenum that is coupled to the source of heated gas and a lower plenum, and a distribution plate that provides a lower surface of the arm and that has a plurality of openings disposed uniformly across the distribution plate, and wherein the diffusion plate includes a plurality of apertures distributed non-uniformly across the diffusion plate so as to induce a non-uniform mass flow of the heated gas through the plurality of openings.   
     
     
         18 . The apparatus of  claim 17 , wherein the platen is rotatable about an axis of rotation. 
     
     
         19 . The apparatus of  claim 18 , wherein the plurality of apertures are distributed such that the mass flow rate is a monotonically increasing function of radial distance from the axis of rotation of the platen. 
     
     
         20 . The apparatus of  claim 19 , wherein the plurality of apertures are distributed such that the mass flow rate is a parabolically increasing function of radial distance from the axis of rotation of the platen.