Adjustable gap chemical mechanical polishing method and apparatus

Abstract

A polishing apparatus for polishing a surface of wafer is provided. The apparatus includes a carrier to hold the workpiece. An array of fluid nozzles are placed across from the surface of the wafer to provide a gap between the nozzles and the surface of the workpiece. A polishing pad positioned within the gap and configured to polish the surface of the workpiece when a fluid is applied from the plurality of nozzles to push the polishing pad to the surface.

1 . A polishing apparatus for polishing a surface of a workpiece comprising: 
 a carrier surface configured to hold the workpiece;    a plurality of fluid nozzles placed across from the surface to provide a gap between the nozzles and the surface of the workpiece; and    a polishing pad positioned within the gap and configured to polish the surface of the workpiece when a fluid is applied from the plurality of nozzles to push the polishing pad to the surface.    
     
     
         2 . The polishing apparatus of  claim 1 , wherein an isolation region separates fluid nozzles from one another.  
     
     
         3 . The polishing apparatus of  claim 2 , wherein the isolation region drain the fluid after the step of applying the fluid to the polishing pad.  
     
     
         4 . The polishing apparatus of  claim 1 , wherein the fluid nozzles are arranged into a plurality of zones.  
     
     
         5 . The polishing apparatus of  claim 1 , wherein isolation regions separate zones from one another.  
     
     
         6 . The polishing apparatus o f  claim 4 , wherein the plurality of zones are circular and disposed concentrically.  
     
     
         7 . The polishing apparatus of  claim 4  further comprising at least one regulator associated with each zone and configured to modify the fluid flow from the nozzles to create a desired fluid flow rate profile.  
     
     
         8 . The polishing apparatus of  claim 1  wherein the fluid nozzles are configured to be moved close to or away from the polishing pad.  
     
     
         9 . The polishing apparatus of  claim 1 , wherein the polishing pad is configured to be moved with respect to the fluid nozzles.  
     
     
         10 . The polishing apparatus of  claim 1 , wherein the polishing pad is configured to be moved bilinearly.  
     
     
         11 . The polishing apparatus of  claim 1 , wherein the fluid nozzles are placed above the surface of the workpiece.  
     
     
         12 . The polishing apparatus of  claim 1 , wherein the polishing pad is a fixed abrasive pad.  
     
     
         13 . The polishing apparatus of  claim 1 , wherein the polishing pad is a polymeric pad.  
     
     
         14 . The polishing apparatus of  claim 1 , wherein the surface of the wafer comprises copper.  
     
     
         15 . The polishing apparatus of  claim 1 , wherein the fluid is air.  
     
     
         16 . A method of polishing a surface of a workpiece surface using a polishing pad, the method comprising the steps of: 
 placing the polishing pad within a gap defined between the surface of the workpiece and an array of nozzles;    emitting a fluid from the array of nozzles to push the polishing pad onto the surface of the workpiece; and    polishing the surface with the polishing pad while keeping the gap constant.    
     
     
         17 . The method of  claim 16  further comprising the step of removing the fluid through the isolation space between the array of nozzles.  
     
     
         18 . The method of  claim 16 , wherein the step of polishing comprises establishing a relative motion between the polishing pad and the surface.  
     
     
         19 . The method of  claim 16  further comprising the step of reducing the gap to increase the material removal rate from the surface.  
     
     
         20 . The method of  claim 19  further comprising the step of continuing polishing the surface with the polishing pad after the step of reducing the gap.  
     
     
         21 . The method of  claim 19 , wherein the step of reducing the gap is performed by moving the array of nozzles close to the surface.  
     
     
         22 . The method of  claim 19 , wherein the step of reducing the gap is performed by moving the surface close to the array of nozzles.  
     
     
         23 . The method of  claim 16  further comprising the step of increasing the gap to decrease the material removal rate from the surface.  
     
     
         24 . The method of  claim 23  further comprising the step of continuing polishing the surface with the polishing pad after the step of increasing the gap.  
     
     
         25 . The method of  claim 23 , wherein the step of increasing the gap is performed by moving the array of nozzles away from the surface.  
     
     
         26 . The method of  claim 23 , wherein the step of increasing the gap is performed by moving the surface away from the array of nozzles.  
     
     
         27 . The method of  claim 18 , wherein the array of nozzles includes a plurality of zones and the step of emitting fluid comprises emitting fluid with different flow rates from each zone.  
     
     
         28 . The method of  claim 27  further comprising the step of removing the fluid through the isolation space between the zones.  
     
     
         29 . The method of  claim 16  further comprising delivering a polishing slurry between the surface of the workpiece and the polishing pad.  
     
     
         30 . The method of  claim 18 , wherein the step of establishing a relative motion includes moving the polishing pad bi-linearly over the array of nozzles while rotating the surface of the workpiece on the polishing pad.  
     
     
         31 . The method of  claim 16  further comprising the step of increasing the flow rate of the fluid to increase material removal rate from the surface.  
     
     
         32 . The method of  claim 16  further comprising the step of decreasing the flow rate of the fluid to decrease the material removal rate from the surface.  
     
     
         33 . The method of  claim 27 , wherein the step of emitting fluid with different flow rates from each zone comprises emitting fluid with a flow rate from a zone and emitting fluid with another flow rate from another zone.