Substrate structure of monolithic gas sensor

Details Substrate structure of monolithic gas sensor Substrate structure of monolithic gas sensor

1996-08-26

1997-08-19

Williams, Hezron E.

Measuring and testing

Gas analysis

Detector detail

7333505, 422 88, 422 94, 338334, G01N 2712

Patent

active

056591276

ABSTRACT:
A substrate structure of a monolithic gas sensor is disclosed, wherein the substrate structure is formed as a thermal resistant and insulating suspended thin plate configuration on a single crystal silicon substrate. The thin plate has formed thereon a heating resistor and coated with tin-oxide-base reducing gas-sensitive material. The thermal resistant thin plate formed on the silicon substrate comprises a native silicon oxide layer, a silicon-rich silicon nitride layer deposited on the native silicon oxide layer, and a top silicon oxide layer formed by thermal oxidation of a surface layer of the deposited silicon-rich silicon nitride layer. An oxide-nitride-oxide sandwiched composited configuration is thus formed that can relieve mechanical stresses internal to the thin plate. The suspended thermal resistantthin plate has corrugation portions formed near the plate edges for relieving mechanical stresses arising from thermal expansion of the silicon substrate and the thin plate when heated to high temperature. The heating resistor formed on the thin plate comprises a polysilicon layer and is covered by a passivation and then by an aluminum oxide layer having a thickness of about several hundred angstroms. The coated tin-oxide-based material is formed by thick-film screen printing to form a sensor film for the single-chip sensing element. Improved thermal and mechanical stress characteristics are obtained while achieving lower electrical power consumption and also maintaining low cost of manufacturing when batched produced.

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Catalogue of a product with Model No. TGS813 of Figaro Engineering, Inc., Whole catalogue.
Wee-Hin et al, "Motorola Micromachined Thin-Film Gas Sensor", Technical data from Sensors Expo. 1996 Exhibition in Anaheim Los Angeles.

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