Heterodyne reflectometer for film thickness monitoring and method for implementing
US7339682B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Feb 25, 2005 |
| Grant date | Mar 4, 2008 |
| Priority date | — |
| Expiry date | Jul 28, 2025 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01B11/0641
- WIPO fieldMeasurement
- WIPO sectorInstruments
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. A grating interferometer may be included with the heterodyne reflectometer system with a grating, which diffracts the reflected beam into zeroth- and first-order bands, which are then detected by separate detectors. A detector receives the zeroth-order beam and genera…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.