Wright State University

Eileen Pimentel

David C Look

An apparatus for measuring the average characteristics of a semiconductor wafer. The apparatus comprises four electrical contacts removably connected to the wafer at generally equidistant positions on the periphery of the wafer and a flat permanent magnet positioned, adjacent the wafer for applying a substantially uniform magnetic field to one surface of the wafer. The apparatus further comprises control apparatus, connected to each of the electrical contacts for applying current successively to each of four sets of adjacent electrical contacts and measuring the voltage across the opposing set of adjacent electrical contacts in response to each application of current and to each of two sets of opposing electrical contacts and measuring the voltage across the other set of opposing electrical contacts in response to each application of current. As a result, the average dark resistivity, the average dark carrier mobility, and the average dark carrier concentration of the wafer are determined. The apparatus may also be adapted to measure the average light characteristics of a photoconductive semiconductor wafer, wherein the apparatus further comprises a light source for directing light of substantially uniform intensity toward the other surface of the wafer, whereby the average light resistivity, the average light carrier mobility and the average light carrier concentration of the wafer are determined.

Method and apparatus for measuring average resistivity and hall-effect

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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Dayton, OH, United States of America

Eileen Pimentel