An ellipsometer includes a light source for generating a probe beam of polychromatic light for interacting with a sample. A polarizer is used to impart a known polarization state to the probe beam and the polarized probe beam is directed against the sample at a shallow angle of incidence. A rotating compensator is used to impart phase retardations to the polarization state of the reflected probe beam. After passing through the compensator, the probe beam passes through a second polarizer (analyzer). After leaving the analyzer, the probe beam is received by a detector. The detector translates the received probe beam into a signal that includes DC, 2.omega. and 4.omega. signal components (where .omega. is the angular velocity of the rotating compensator). A processor analyzes the signal using the DC, 2.omega. and 4.omega. components allowing simultaneous evaluation of both critical dimensions and film parameters.
PRIORITY CLAIM
The present application claims priority to U.S. Provisional Patent Application Ser. No. 60/346,265, filed Dec. 19, 2001, the disclosure of which is incorporated herein by reference.
A normal incidence rotating compensator ellipsometer includes an illumination source that produces a broadband probe beam. The probe beam is redirected by a beam splitter to be normally incident on a sample under test. Before reaching the sample, the probe beam is passed through a rotating compensator. The probe beam is reflected by the sample and passes through the rotating compensator a second time before reaching a detector. The detector converts the reflected probe beam into equivalent signals for analysis.
A normal incidence rotating compensator ellipsometer includes an illumination source that produces a broadband probe beam. The probe beam is redirected by a beam splitter to be normally incident on a sample under test. Before reaching the sample, the probe beam is passed through a rotating compensator. The probe beam is reflected by the sample and passes through the rotating compensator a second time before reaching a detector. The detector converts the reflected probe beam into equivalent signals for analysis.
