Radiant energy – Invisible radiant energy responsive electric signalling – With means to inspect passive solid objects
Patent
1989-10-03
1991-01-29
Anderson, Bruce C.
Radiant energy
Invisible radiant energy responsive electric signalling
With means to inspect passive solid objects
G01F 2300
Patent
active
049888773
ABSTRACT:
Method and apparatus for determining the amount, if any, of residue remaining at the bottom of an aperture in a layer of dielectric or insulator material. A layer of electrically conducting material is positioned adjacent to the aperture bottom, an electron collector is positioned adjacent to the mouth of the aperture, and a voltage difference (optional) is impressed between the conducting material and the electron collector. The aperture bottom is illuminated with a light beam with photon energy greater than the electron work function of the conducting material, and a portion of the photons that comprise the light beam reach the conducting material and produce photoelectrons by photoemissive action. A photoelectron current is sensed by the electron collector, and the cleanliness of the aperture bottom is determined from the value of the current.
REFERENCES:
patent: 4443278 (1984-04-01), Zingher
patent: 4578279 (1986-03-01), Zingher
patent: 4590376 (1986-05-01), Smith
patent: 4680084 (1987-07-01), Heimann et al.
patent: 4725332 (1988-02-01), Spohr
S. N. Levine, Quantum Physics of Electronics, MacMillan Co., 1965, pp. 150-154.
Neukermans Armand P.
Stokowksi Stanley
Wolze David
Anderson Bruce C.
Schipper John
Schneck Thomas
Tencor Instruments
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