Calibration as well as measurement on the same workpiece during fabrication

Abstract

A method of fabricating a wafer includes forming a portion of the wafer, making a first measurement in the wafer using a first process, making a second measurement in the wafer using a second process each time the first measurement is made, using one of the first measurement and the second measurement to calibrate the other of the first measurement and the second measurement, and changing a process control parameter used in forming the portion of the wafer depending on the first measurement and on the second measurement.

1 . A method of fabricating a wafer, the method comprising: 
 forming a portion of a wafer;    making a first measurement in the wafer using a first process; making a second measurement in the wafer using a second process each time said first measurement is made;    using one of the first measurement and the second measurement to calibrate the other of the first measurement and the second measurement; and    changing a process control parameter used in forming the portion of the wafer depending on the first measurement and on the second measurement.    
   
   
       2 . The method of  claim 1  wherein: 
 said second measurement is used to calibrate said first measurement;    said using comprises: based on the second measurement, generating a model of a property of the portion of the workpiece as a function of the first measurement; and    looking up the model to determine a value of the property, based on the first measurement.    
   
   
       3 . The method of  claim 1  wherein: 
 said changing of process control parameter is done only if the value of the property exceeds or falls below a predetermined limit.    
   
   
       4 . The method of  claim 1  further comprising: 
 repeating said first measurement and said second measurement in said wafer a plurality of times.