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:
Mar. 20, 1990
Filed:
Oct. 15, 1987
Robert C Abbe, Newton, MA (US);
Noel S Poduje, Needham Heights, MA (US);
ADE Corporation, Newton, MA (US);
Abstract
An error compensated thickness measuring system utilizing first and second probes placed on opposite sides of a semiconductor wafer whose thickness is to be measured. The output of the probes is linearized and electronically processed to provide a signal representative of the thickness of the semiconductor wafer. The electronic processing includes an error compensating circuit which removes higher order error in the thickness signal attributable to the wafer being other than precisely centered between the two probes. The error compensating circuitry operates to produce a scaled higher order representation of the displacement of the wafer from the centered condition to combine this with the thickness signal to produce an error compensated signal. The present invention finds particular application in the thickness gauging of semiconductor wafers which represent a substantial impedance to circuit common and in which compensating circuitry is utilized to adjust for or control the potential of the ungrounded object.