A method for characterizing 
semiconductor device performance variations includes 
processing a 
wafer in a 
processing line to form a feature on the 
wafer; measuring a physical 
critical dimension of the feature in a first 
metrology tool to generate a first 
critical dimension measurement; measuring the physical 
critical dimension of the feature in a second 
metrology tool to generate a second critical 
dimension measurement independent of the first critical 
dimension measurement; determining an effective critical dimension of the feature in a third 
metrology tool to generate a third critical 
dimension measurement; and comparing the first, second, and third critical dimension measurements to identify a metrology drift in one of the first and second metrology tools. A 
system for characterizing 
semiconductor device performance variations includes a 
processing line, first, second, and third metrology tools, and a process controller. The processing line is adapted to process a 
wafer to form a feature on the wafer. The first metrology tool is adapted to measure a physical critical dimension of the feature to generate a first critical dimension measurement. The second metrology tool is adapted to measure the physical critical dimension of the feature to generate a second critical dimension measurement independent of the first critical dimension measurement. The third metrology tool adapted to determine an effective critical dimension of the feature to generate a third critical dimension measurement. The process controller is adapted to compare the first, second, and third critical dimension measurements to identify a metrology drift in one of the first and second metrology tools.