Miniature gauge pressure sensor using silicon fusion bonding and back etching
US6629465B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Nov 24, 1999 |
| Grant date | Oct 7, 2003 |
| Priority date | — |
| Expiry date | Nov 24, 2019 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01L9/0042
- WIPO fieldMeasurement
- WIPO sectorInstruments
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.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.