CMP point of use filtration

Abstract

A system for detecting the usable state of a point of use filter of a chemical mechanical polishing (CMP) tool. The system measures the pressure differential across the point of use filter. In one example, the system includes an upstream and a down stream pressure transducer for measuring the pressure differential. The system can provide an indication that the usable state of filter has decreased to a point where the filter needs to be replaced. Such an indication may be displayed on a display located on the polishing tool frame.

What is claimed is:  
     
         1 . A method for polishing a semiconductor wafer in a polishing tool, the method comprising: 
 controlling by a flow regulator at a first location in a slurry path to a polishing pad, a flow rate of slurry to a polishing pad;    filtering, with a point of use filter, the slurry at a second location in the slurry path located downstream of the first location;    measuring a first pressure in the slurry path upstream of the filter;    measuring a second pressure in the slurry path down stream of the filter;    providing the slurry to the polishing pad;    polishing the semiconductor wafer with the polishing pad;    providing an indication including information based upon a pressure differential between the first pressure and the second pressure wherein the pressure differential is indicative of a usable state of the point of use filter.    
     
     
         2 . The method of  claim 1 , further comprising: 
 calculating the pressure differential, wherein the information includes the pressure differential.    
     
     
         3 . The method of  claim 2  further comprising: 
 displaying the pressure differential.  
 
     
     
         4 . The method of  claim 1 , wherein the indication indicates that the pressure differential exceeds a predetermined threshold pressure.  
     
     
         5 . The method of  claim 4  wherein the predetermined threshold pressure corresponds to the usable state of the filter being such that the filter needs to be replaced.  
     
     
         6 . The method of  claim 4  further comprising: 
 displaying an indication that the filter needs to be replaced in response to the indication indicating that the pressure differential exceeds a predetermined threshold pressure.  
 
     
     
         7 . The method of  claim 6 , further comprising: 
 changing a filter used to filter the slurry in response to receiving the displayed indication.    
     
     
         8 . The method of  claim 7  wherein the changing the filter includes snapping the filter into a notch in a bracket.  
     
     
         9 . The method of  claim 1  further comprising: 
 displaying the indication on a display.  
 
     
     
         10 . The method of  claim 1  further comprising: 
 providing the indication to a system controller of the polishing tool.  
 
     
     
         11 . A semiconductor wafer polishing tool comprising: 
 a slurry path to provide slurry to a polishing pad;    a flow regulator located in the slurry path and controlling the flow rate of the slurry to the polishing pad during polishing;    a point of use filter located in the slurry path downstream from the flow regulator;    a first pressure sensor located in the slurry path upstream from the point of use filter, the first pressure sensor measuring a first pressure and providing a first indication of the first pressure;    a second pressure sensor located in the slurry path downstream from the point of use filter, the second pressure sensor measuring a second pressure and providing a second indication of the second pressure; and    a pressure differential indicator coupled to receive the first indication and the second indication, the pressure differential indicator providing a third indication, the third indication including information based upon a pressure differential between the first pressure as indicated by first indication and the second pressure as indicated by the second indication, wherein the pressure differential is indicative of a usable state of the point of use filter.    
     
     
         12 . The polishing tool of  claim 11 , wherein the third indication includes a value of the pressure differential.  
     
     
         13 . The polishing tool of  claim 11 , wherein the pressure differential indicator further includes a display, the display displaying the third indication.  
     
     
         14 . The polishing tool of  claim 13  wherein the third indication indicates that the filter needs to be replaced as based upon the pressure differential exceeding a predetermined threshold pressure.  
     
     
         15 . The polishing tool of  claim 11 , wherein the pressure differential further includes a controller operably coupled to receive the first indication and the second indication, wherein the controller calculates the pressure differential between the first pressure as indicated by first indication and the second pressure as indicated by the second indication wherein the third indication is based upon the pressure differential calculated.  
     
     
         16 . The polishing tool of  claim 11 , wherein the third indication includes an indication that the pressure differential exceeds a predetermined threshold pressure.  
     
     
         17 . The polishing tool of  claim 16  wherein the predetermined threshold pressure corresponds to the usable state of the filter being such that the filter needs to be replaced.  
     
     
         18 . The polishing tool of  claim 11 , further comprising a system controller operably coupled to the pressure differential indicator to receive the third indication.  
     
     
         19 . The polishing tool of  claim 18  further comprising a system display operably coupled to the system controller to receive information regarding the third indication for display on the system display.  
     
     
         20 . The polishing tool of  claim 11 , further comprising an isolation valve located in the slurry pathway downstream from the point of use filter, wherein the slurry travels through the isolation valve at a flow rate determined by the flow regulator.  
     
     
         21 . The polishing tool of  claim 11  further comprising: 
 a dispense arm located in the slurry path downstream from the point of use filter, wherein the dispense arm provides the slurry to the polishing pad.  
 
     
     
         22 . The polishing tool of  claim 11 , wherein the flow regulator includes a peristaltic pump.  
     
     
         23 . The polishing tool of  claim 11 , wherein the pressure differential indicator includes a display and a controller, wherein the controller is operably coupled to receive the first indication and the second indication, wherein the controller calculates the pressure differential between the first pressure as indicated by first indication and the second pressure as indicated by the second indication, wherein the display displays information based the pressure differential as calculated by the controller.  
     
     
         24 . The polishing tool of  claim 11 , further comprising a first pressure sensor includes a first pressure transducer and the second pressure sensor includes a second pressure transducer.  
     
     
         25 . The polishing tool of  claim 11 , further comprising: 
 a frame, wherein the polishing pad is located within the frame and wherein the point of use filter is located within the frame.    
     
     
         26 . The polishing tool of  claim 11  further comprising: 
 a frame;  
 a bracket mechanically coupled to the frame, the bracket including a notch sized to receive the filter in a snap-in configuration.  
 
     
     
         27 . A filtration system for a chemical mechanical polishing tool comprising: 
 a slurry path having a first end to receive a slurry from a flow regulator and an second end for providing slurry for its application to a polishing pad for polishing, the slurry regulated at a flow rate by the flow regulator;    a point of use filter located in the slurry path downstream of the first end;    a first pressure sensor located in the slurry path upstream from the point of use filter, the first pressure sensor measuring a first pressure and providing a first indication of the first pressure;    a second pressure sensor located in the slurry path downstream from the point of use filter, the second pressure sensor measuring a second pressure and providing a second indication of the second pressure; and    the pressure differential indicator providing a third indication, the third indication including information based upon a pressure differential between the first pressure as indicated by first indication and the second pressure as indicated by the second indication, wherein the pressure differential is indicative of a usable state of the point of use filter.    
     
     
         28 . The system of  claim 27 , wherein the pressure differential indicator includes a display, the display displaying the third indication.  
     
     
         29 . The system of  claim 28  wherein the third indication indicates that the filter needs to be replaced as based upon the pressure differential exceeding a predetermined threshold pressure.  
     
     
         30 . The system of  claim 27 , wherein the third indication includes an indication that the pressure differential exceeds a predetermined threshold pressure.  
     
     
         31 . The system of  claim 30  wherein the predetermined threshold pressure corresponds to the usable state of the filter being such that the filter needs to be replaced.  
     
     
         32 . The system of  claim 27 , wherein the pressure differential indicator includes a display and a controller, wherein the controller is operably coupled to receive the first indication and the second indication, wherein the controller calculates the pressure differential between the first pressure as indicated by first indication and the second pressure as indicated by the second indication, wherein the display displays information based the pressure differential as calculated by the controller.