High accuracy film thickness measurement system
US4776695A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 2, 1986 |
| Grant date | Oct 11, 1988 |
| Priority date | — |
| Expiry date | Sep 2, 2006 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01B11/0633
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A system for ascertaining the thickness of thin films, especially on semiconductor substrates, comprising a light source, a randomized bifurcated fiber optic bundle, a pentamirror, a rapid scanning monochromator with a rotating grating, a photodetector, and A/D converter, an interface and a data reduction computer. The randomized bifurcated fiber optic bundle via the pentamirror directs light to and receives reflected light from a surface of the thin film, the reflected light passes through the bifurcated bundle to the monochromator and to the photodetector whose output is read by the A/D converter. A timing control circuit is provided which has an input from an encoder coupled to the motor rotating the grating and clock and trigger outputs coupled to the A/D converter so that the A/D converter consistently samples the analog signal representative of the same portions of the reflected visible spectra returned from the thin film under test.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.