Computer integrated manufacturing control system for oxide chemical mechanical polishing

Abstract

A new method is provided that extends the process of automation of the CMP process by monitoring the in-line removal rate, by using methods of curve-fitting that enable a reduction in the frequency of monitoring the removal rate of the CMP process, by enhancing the life expectancy of the polishing pad thereby further reducing the frequency of the required Preventive Maintenance and by allowing for the polishing of non-standard lots of wafers.

1 .- 14 . (canceled)  
   
   
       15 . A system to determine a Base Removal Rate (RR), comprising: 
 a means for measuring in off-line mode a thickness of a layer of semiconductor material before and after Chemical Mechanical Polishing (CMP); and    a means for calculating a Peak Removal Rate (RR) using a Peak RR End Point mode function.    
   
   
       16 . The system of  claim 15 , said Peak RR End Point mode function comprising: 
 a means for focusing a laser created light beam on the surface of a wafer, said laser light beam being reflected by the surface of said wafer;    a means for analyzing said reflected light beam by recognizing a CMP end-point therein.    
   
   
       17 . The system of  claim 16 , said recognizing a CMP end-point comprising means for curve fitting.  
   
   
       18 . The system of  claim 16 , said Peak RR End Point mode function being performed in-situ.  
   
   
       19 . The system of  claim 17 , said means for curve fitting comprising creating a mathematical expression that, when plotted, closely fits a reference set of data points.  
   
   
       20 . The system of  claim 15 , said thickness of a layer of semiconductor material before and after Chemical Mechanical Polishing (CMP) being used as input to said Peak RR End Point mode function.  
   
   
       21 . A system to extend a polishing pad-use, comprising means for polishing under reduced pressure for first period of time.  
   
   
       22 . The system of  claim 21 , said first period of time being ten hours.  
   
   
       23 . The system of  claim 21 , said system further being extended by providing means for initially “breaking-in” polishing pads, said “breaking-in” comprising using said polishing pads on a separate line, said separate line having a lower removal rate than a regular polishing line by a measurable amount.  
   
   
       24 . The system of  claim 21 , said system further being extended by providing means for changing polishing conditions dependent on length of time that a polishing pad has been used.  
   
   
       25 . The system of  claim 21 , said system being controlled by a Computer Integrated Manufacturing (CIM) acting in a Supervisory and Controlling capacity.  
   
   
       26 . The system of  claim 15 , said system further being extended with means for monitoring wafers simultaneously being polished on two platens, comprising means for calculating a Removal Rate (RR) using an equation for a two-platen polishing arrangement.  110 . The system of claim  109 , said equation for calculating a Removal Rate (RR) using an equation for a two-platen polishing arrangement being RR=(RR 1 +RR 2 )/2, whereby RR 1 =A 1 /(t 1 −B 1 ) for platen  1  and RR 2 =A 2 /(t 2 −B 2 ) for platen  2 , whereby of these parameters A 1  is a removal thickness for platen  1 , A 2  is a removal thickness for platen  2 , B 1  is an off-set value for platen  1 , B 2  is an off-set value for platen  2 , t 1  is a polishing time for platen  1  and t 2  is a polishing time for platen  2 , whereby values for A 1 , A 2 , B 1  and B 2  are measured by optical methods using laser technology, values for t 1  and t 2  are controlled by a host computer on which a CIM function resides.  
   
   
       27 . The system of  claim 26 , said system being extended with means for, if an absolute vale of RR 1 −RR 2 >750, a CIM function places a hold on the monitor wafer and invokes engineering intervention by creating a message stating that “RR between P 1  and P 1  larger than 750, wait for Engineering evaluation”.