The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Aug. 15, 1989
Filed:
Mar. 02, 1988
David C Look, Dayton, OH (US);
Eileen Pimentel, Dayton, OH (US);
Wright State University, Dayton, OH (US);
Abstract
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.