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:
Sep. 22, 1992
Filed:
Sep. 23, 1991
David C Look, Dayton, OH (US);
Philip D Mumford, Dayton, OH (US);
Abstract
A non-destructive measurement system for producing whole wafer maps of sheet Hall concentration and Hall mobility in a GaAs wafer. The wafer need only have van der Pauw patterns available for the wafer measurements to be made. The measurement system includes an automatic test prober apparatus modified to incorporate a powerful permanent magnet providing a magnetic field to produce a Hall effect in the GaAs wafer. A parametric measurement system coupled through test probes to the van der Pauw patterns is programmed to measure sheet resistivity, Hall voltage and magnetic field strength, from which are derived values of sheet Hall concentration and mobility that are stored and mapped.