Thermal mass gas flow sensor and method of forming same
First Claim
1. A thermal mass gas flow sensor, comprising:
- a substrate and at least one pair of thermal sensing elements disposed on said substrate;
a heater, disposed on said substrate, between said thermal sensing elements; and
a protective layer disposed on at least said heater and/or said thermal sensing elements, wherein said protective layer comprises a high temperature resistant insulating or dielectric layer.
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Abstract
A thermal gas flow sensor and method of forming such a sensor. The sensor has a substrate and a heater disposed on the substrate. At least one pair of thermal sensing elements is disposed on the substrate either side of the heater. A protective layer is disposed on at least the heater and/or the thermal sensing elements. The protective layer comprises a high temperature resistant polymer based layer which is preferably a fluoropolymer based layer. The protective layer can also cover interconnects and electrical connections also formed on the substrate so as to completely seal the sensor. A passivation layer, such as silicon nitride, can be disposed on the sensing and/or heating elements and optionally the interconnects and is arranged to interpose the protective layer and the substrate.
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Citations
20 Claims
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1. A thermal mass gas flow sensor, comprising:
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a substrate and at least one pair of thermal sensing elements disposed on said substrate;
a heater, disposed on said substrate, between said thermal sensing elements; and
a protective layer disposed on at least said heater and/or said thermal sensing elements, wherein said protective layer comprises a high temperature resistant insulating or dielectric layer. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A thermal gas micro flow sensor comprising:
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a substrate;
a heater disposed on said substrate;
at least one pair of thermal sensing elements disposed on said substrate either side of said heater; and
a protective layer, disposed on at least said heater and/or said thermal sensing elements, wherein said protective layer comprises an high temperature resistant polymer based layer. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15, 16)
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17. A method of manufacturing a thermal mass gas flow sensor comprising:
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providing a substrate;
forming at least one pair of temperature sensing elements on said substrate;
forming a heating element on said substrate between said at least one pair of temperature sensing elements, and forming a protective layer on at least said temperature sensing elements and/or said heating elements, wherein said protective layer comprises a high temperature resistant polymer based layer. - View Dependent Claims (18, 19, 20)
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Specification