Kenneth P Harvey

US Patent:

7339682, Mar 4, 2008

Filed:

Feb 25, 2005

Appl. No.:

11/066933

Inventors:

Arun Ananth Aiyer - Fremont CA, US
Mark A. Meloni - Flower Mound TX, US
Kenneth C. Harvey - Dallas TX, US
Andrew Weeks Kueny - Dallas TX, US

Assignee:

Verity Instruments, Inc. - Carrollton TX

International Classification:

G01B 9/02

US Classification:

356504, 356485, 356492

Abstract:

The present invention is directed to a heterodyne reflectometer system and method for obtaining highly accurate phase shift information from heterodyned optical signals, from which extremely accurate film depths can be calculated. A linearly polarized light comprised of two linearly polarized components that are orthogonal to each other, with split optical frequencies, is directed toward a film causing one of the optical polarization components to lag behind the other due to an increase in the optical path in the film for that component. A pair of detectors receives the beam reflected from the film layer and produces a measurement signal, and the beam prior to incidence on the film layer and generates a reference signal, respectively. The measurement signal and reference signal are analyzed by a phase detector for phase shift. The detected phase shift is then fed into a thickness calculator for film thickness results.