Electricity: measuring and testing – Measuring – testing – or sensing electricity – per se – With rotor
Patent
1988-03-02
1989-03-28
Eisenzopf, Reinhard J.
Electricity: measuring and testing
Measuring, testing, or sensing electricity, per se
With rotor
324 64, 324158D, 324501, G01R 3100
Patent
active
048167550
ABSTRACT:
A method and apparatus for measuring the characteristics of a photoconductive semiconductor wafer. The apparatus comprises a light source for directing light of substantially uniform intensity toward one surface of the wafer. The apparatus further comprises masking apparatus, interposed between the wafer and light source, for transmitting the light to the wafer in the shape of a cross formed by a pixel of light at the intersection of the cross and four paths extending outwardly from the pixel to the periphery of the wafer. The apparatus also comprises a first set of contacts for providing an electrical contact with the paths of light. The apparatus further comprises control apparatus connected to each of the contacts of the first set, for applying current successively to each of four sets of adjacent paths of light and measuring the voltage across the opposing set of adjacent paths in response to each application of current. As a result, the resistivity of a first portion of the wafer illuminated by the projection of the pixel of light through the wafer is determined. The apparatus may also comprise a magnet for applying a substantially uniform magnetic field to the other surface of the wafer. As a result, the carrier mobility and carrier concentration of the first portion of the wafer illuminated by the projection of the pixel light are determined.
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Look David C.
Pimentel Eileen
Burns W.
Eisenzopf Reinhard J.
Wright State University
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