Method for making thin film orthogonal microsensor for air flow
US4895616A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 24, 1989 |
| Grant date | Jan 23, 1990 |
| Priority date | — |
| Expiry date | Apr 24, 2009 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01H2001/0089
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A microbridge air flow sensor which has a sealed etched cavity beneath the silicon nitride diaphragm so that the cavity is not susceptible to contamination from residual films or other material accumulating within the cavity. The cavity thermally isolates the heater and detectors which are encapsulated in the diaphragm. The cavity is fabricated by front side etching of the silicon wafer. Narrow slots are made through the silicon nitride diaphragm to expose a thin film (400 angstrom) rectangle of aluminum. A first etch removes the aluminum leaving a 400 angstrom very shallow cavity under the diaphragm. Anisotropic etch is then introduced into the shallow cavity to etch the silicon pit.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.