Patent ID: 6801309
Filing Date: 2004-10-05
Classification: G01J

Abstract:
An apparatus for measuring the intensity of broadband light across a range of wavelengths, said broadband light being collected after reflecting from a sample in a metrology tool, said apparatus comprising:an optical element for angularly dispersing the broadband light along a first axis as a function of wavelength; a first photodetector array positioned to receive light dispersed from the optical element along the first axis and oriented to measure light specularly reflected from the sample and generating first output signals as function of wavelength; a second photodetector array positioned along side of the first photodetector array and extending parallel to said first axis and oriented to measure light scattered as the light passes through the metrology tool and generating second output signals as a function of wavelength and distance from the first photodetector array; and a processor for using the second output signals to correct the information derived from the first output signals as a function of wavelength, the processor further using the second output signals to correct information derived from the first output signals for each detector element of the first photodetector array by extrapolating measured light values from neighboring detector elements of the second photodetector array in order to account for scattered light in the first output signals.