Methods and apparatus for identifying the material of a particle occurring on the surface of a substrate
US6122047A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 14, 1999 |
| Grant date | Sep 19, 2000 |
| Priority date | — |
| Expiry date | Jan 14, 2019 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N2021/556
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
The composition of a particle occurring on the surface of a smooth substrate is identified by impinging the surface with a light beam having a strong P-polarized component at an oblique angle of incidence to the surface, and collecting light scattered from the surface at forward, center, and back locations relative to the portion of the surface impinged by the incident beam. The intensities of the light collected at these locations are measured by detectors and converted into signals, and the magnitudes of the signals are compared to correlations of particle material as a function of the relative magnitudes of the forward-, center-, and back-scatter signals so as to identify the material whose correlation most nearly matches the measured detector signals. Preferably, a ratio of the back detector signal magnitude to forward detector signal magnitude is correlated with particle material and back detector signal magnitude. Alternatively or additionally, a ratio of back detector signal magnitude to center detector signal magnitude is correlated with particle material and back detector signal magnitude. Average particle diameter versus back detector signal magnitude is correlated with p…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.