Patent ID: 7505148

Claim:
A method of matching optical metrology tools, the method comprising: obtaining a first set of measured diffraction signals, wherein the first set of measured diffraction signals was measured using a first optical metrology tool; obtaining a second set of measured diffraction signals, wherein the second set of measured diffraction signals was measured using a second optical metrology tool; generating a first spectra-shift offset based on the difference between the first set of measured diffraction signals and the second set of measured diffraction signals; generating a first noise weighting function for the first optical metrology tool based on measured diffraction signals measured using the first optical metrology tool; obtaining a first measured diffraction signal measured using the first optical metrology tool; generating a first adjusted diffraction signal by adjusting the first measured diffraction signal using the first spectra-shift offset and the first noise weighting function; and storing the first adjusted diffraction signal.