Photoemission contaminant detector
US4998019A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 3, 1989 |
| Grant date | Mar 5, 1991 |
| Priority date | — |
| Expiry date | Oct 3, 2009 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N23/227
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Methods for determining the presence or absence of, and the thickness or other spacial extent of, a contaminant layer at each of a plurality of two or more sites on the surface of an electrically conductive material such as a semiconductor, a metal or a metal silicide. The invention uses a change in photoemission current from an illuminated spot on the surface to determine the presence and extent of a contaminant layer at the illuminated site. Compensation is provided for the effects of capacitive current and photovoltaic current. The invention provides a pattern of illumination sites on the conductor surface that can, if desired, cover all points on the surface.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.