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:
Oct. 07, 2003
Filed:
Nov. 24, 1999
Nadim I. Maluf, Mountain View, CA (US);
John R. Logan, Danville, CA (US);
Gertjan van Sprakelaar, Fremont, CA (US);
NovaSensor Inc., Fremont, CA (US);
Abstract
A gauge or differential pressure sensor has a base portion having walls which define a cavity within the base portion and a diaphragm portion positioned over the cavity. The base portion comprises silicon; the diaphragm portion comprises silicon; the substrate has a passageway from a surface of the substrate into the chamber; the walls of the cavity form an angle with the diaphragm of no more than ninety degrees; and the chamber has a depth of at least about 5 microns. Preferably, the pressure sensor has a lip within the passageway which prevents an adhesive used to glue the sensor to a base from flowing to the diaphragm and fouling it. The pressure sensor is made by forming a cavity in a first wafer, fusion bonding a second wafer over the first wafer in an oxidizing environment, and using the thin oxide formed when fusion bonding the wafers as an etch stop when opening the cavity to the atmosphere. Etch conditions are selected to form the preferred lip in the passageway. The pressure sensor has improved accuracy and reliability as well as small size.