Micro-heater and airflow sensor using the same
US6450025B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Feb 4, 2000 |
| Grant date | Sep 17, 2002 |
| Priority date | — |
| Expiry date | Feb 4, 2020 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH05B2203/017
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
An airflow sensor including a micro-heater having a film structure, which can reduce a warpage of the film structure even when a thick ness of the film structure to improve a mechanical strength thereof. An airflow sensor is provided with a monocrystalline silicon substrate having a hollow portion therein; a thin film heater portion as a micro-heater arranged above the hollow portion; and a temperature sensor. The thin film heater portion has a laminated structure of a lower thin film, a heater layer, and an upper thin film. The lower and the upper thin film respectively have a tensile stress film and a compressive stress film laminated with the tensile stress film, and are symmetry laminated with respect to the heater layer. The tensile stress film is made up of a Si3N4 film having a great moisture-proof characteristic; and the compressive stress film is made up of a SiO2 film having a great adhesion. Since these stress films cancel their internal stress each other, the internal stress can be released, and a warpage moment can be cancelled so that a warpage of the whole film structure can be restricted. Therefore, the mechanical strength can be improved even if the thickness of th…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.