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US 6,450,025 B1Granted
Micro-heater and airflow sensor using the same
AssigneeDenso Corporation
InventorsHiroyuki Wado, Yoshinori Otsuka, Eishi Kawasaki
Life of this patent
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AssigneeDenso Corporation
InventorsHiroyuki Wado, Yoshinori Otsuka, Eishi Kawasaki
Estimating the term…
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 the film is increased.
A micro-heater comprising:
The micro-heater of claim l wherein:
A micro-heater comprising :
An airflow sensor comprising:
Dependencies are inferred from the claim text.