Patent ID: 7054006
Filing Date: 2006-05-30
Classification: G01J

Abstract:
1. An ellipsometer for optically inspecting a subject, the apparatus comprising: a source for generating an electromagnetic probe beam having a known polarization state; an objective lens for focusing the probe beam on the surface of the subject, the objective lens also collecting the probe beam after it has been reflected by the subject; a rotating compensator for inducing phase retardations in the polarization state of the probe beam; an analyzer positioned to interact with the probe beam; a detector for measuring the intensity of the probe beam after the interaction with the analyzer, said detector being subdivided to provide eight coefficients for measuring the retardation δ a processor for evaluating the sample based on the outputs of the detector, the processor configured to perform a harmonic analysis on the output signal from the detector to determine normalized Fourier coefficients corresponding to 2ω and 4ω components that are included in the output signal; use the Fourier coefficients to measure the retardation δ use the retardation δ