Photoemission contaminant detector

Details Photoemission contaminant detector Photoemission contaminant detector

1989-10-03

1991-03-05

Fields, Carolyn E.

Radiant energy

Invisible radiant energy responsive electric signalling

With means to inspect passive solid objects

2503581, 250372, G01N 2189

Patent

active

049980190

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.

REFERENCES:
patent: 4590376 (1986-05-01), Smith
patent: 4691310 (1987-09-01), Wine
T. Smith, "Photoelectron Emission from Aluminum and Nickel Measured in Air", Jour. Apply. Phys., vol. 46, No. 4, Apr. 1975, pp. 1553-1558.
B. Quiniou et al., "Photoemissive Scanning Microscopy of Doped Regions on Semiconductor Surfaces", Appl. Phys. Lett., vol. 55, No. 5, Jul. 31, 1989, pp. 481-483.

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