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:
Jun. 13, 2000
Filed:
Jun. 16, 1998
Steven Edward Staller, Russiaville, IN (US);
Delphi Technologies, Inc., Troy, MI (US);
Abstract
A method and device for verifying whether a cavity (16) enclosing a micromachined sensing structure (14) between a pair of wafers (10, 12) is hermetically sealed by detecting the presence of moisture within the cavity (16). The method entails forming a bare, unpassivated PN junction diode (20) in a semiconductor substrate, preferably a device wafer (10) with the sensing structure (14). The device wafer (10) is then bonded to a capping wafer (12) to enclose the PN junction diode (20) and micromachine (14) within a cavity (16) defined by and between the wafers (10, 12). The reverse diode characteristics of the PN junction diode (20) are then determined by causing a reverse current to flow through the diode (20). For this purpose, either a known voltage is applied across the diode (20) and the reverse leakage current measured, or a known reverse current is forced across the diode (20) and the voltage measured. The unpassivated junction diode (20) exhibits unstable current/voltage readings if sufficient moisture is present within the cavity (16), thereby indicating whether or not the cavity (16) is hermetically sealed.