Self referencing heterodyne reflectometer and method for implementing
US7589843B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Sep 27, 2006 |
| Grant date | Sep 15, 2009 |
| Priority date | — |
| Expiry date | Jan 10, 2027 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01B2290/70
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A self referencing heterodyne reflectometer is disclosed which rapidly alternates between a heterodyne reflectometry (HR) mode, in which an HR beam comprised of s- and p-polarized beam components at split angular frequencies of ω and ω+Δω is employed, and a self referencing (SR) mode, in which an SR beam comprised of p-polarized beam components at split angular frequencies of ω and ω+Δω is employed. Alternatively, in SR operating mode the SR beam is replaced by a p-polarized amplitude modulated (AM) beam, operating at two modulated amplitudes of α and α+Δα at a single frequency, ω′. When the two measurements are made in rapid succession, using an optical chopper switcher, temperature induced noise in the detector is be assumed to be equivalent. Film phase shift information is derived from the measured phase shift δRef/film, generated from the HR beam, and the reference phase shift δRef/Sub, generated from the SR/AM beam, which are used for calculating film thickness.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.