Interferometer for in situ measurement of thin film thickness changes
US5220405A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 20, 1991 |
| Grant date | Jun 15, 1993 |
| Priority date | — |
| Expiry date | Dec 20, 2011 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01B11/0675
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An interferometer 10 for measuring the position of the process surface 21 of a substrate 20 includes a coherent light source 12 for providing a light beam 14 which is partially transmitted and partially reflected by a beam splitter 16. The reflected light beam 18 is reflected off of the process surface 21 and the transmitted light beam 30 is reflected off of a translator 32 which vibrates a predetermined distance at a predetermined frequency. The phase shift between the light beams 22, 31 reflected off of translator 32 and the process surface 21 is measured using a photodetector 24, which provides an output signal 26 to a feedback servo unit 28. The servo unit 28 provides an output signal 38 which controls the vibration of translator 32. The output signal 38 of servo unit 28 is also indicative of the position of the process surface 21.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.