Photoemission contaminant detector
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United States of America Patent
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Mar 5, 1991
Grant Date -
N/A
app pub date -
Oct 3, 1989
filing date -
Oct 3, 1989
priority date (Note) -
Expired
status (Latency Note)
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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.
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