Gas sensor

Abstract

A gas sensing device comprises: a substrate comprising an etched cavity portion and a substrate portion, a dielectric layer disposed on the substrate, wherein the dielectric layer comprises a dielectric membrane, wherein the dielectric membrane is adjacent to the etched cavity portion of the substrate, a heater located within the dielectric layer; a material for sensing a gas; and one or more polysilicon electrodes coupled with the material for sensing a gas.

Description

technical field [0001] The present disclosure relates to gas sensors, particularly but not limited to micromachined metal oxide gas sensors. Background technique [0002] Metal oxide (MOX) gas sensors are generally based on depositing metal oxide films onto sensing electrodes defined on or within a suitable substrate. Microfabricated MOX gas sensors typically contain a membrane, a heater element within the membrane, and electrodes in direct contact with a metal oxide (MOX) layer. figure 1 A possible structure of a MOX gas sensor is shown in , where a MOX layer is deposited on the membrane and compared with the other by deep reactive ion etching (DRIE) or wet etching (see e.g.: D. Briand et al., "Design and fabrication of high temperature micro -hotplates for drop-coatedgas sensors”, Sensors and Actuators B, 68, pp.223-233, 2000) the cavity formed is opposite. figure 1 The particular example depicted in shows sloped walls that can be achieved by wet etching. Vertical walls...

AI Technical Summary

Problems solved by technology

This additional deposition of gold or platinum adds to the process complexity and increases the production cost of the device

Also, neither gold nor platinum is CMOS compatible (due to possible deep well formation in the semiconductor bandgap), and the issue of process integration for this layer-behind CMOS is challenging from a cost and supply chain perspective

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