Detection of film thickness through induced acoustic pulse-echos
US6552803B1 · kind B1 · utility
29Cited by
33References
64Claims
0Family size
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Key dates
| Filing date | Aug 17, 1999 |
| Grant date | Apr 22, 2003 |
| Priority date | — |
| Expiry date | Aug 17, 2019 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N2291/0427
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Thickness of a film in a sample may be detected by directing pump laser pulses to the surface of a sample to generate an acoustic pulse in a sample. The acoustic pulse propagates downwards until it reaches an interface between the bottom of the film and a substrate and is reflected back to the top surface of the film as a first echo. A reflection of the first echo propagates downwards and is again reflected back towards the surface as a second echo. Heterodyne interferometry is used to measure the lapse of time between the first and second echos from which the thickness of the film may be determined.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.