Fabrication and modelling of CMOS microbridge gas-flow sensors

✍ Scribed by D. Moser; R. Lenggenhager; G. Wachutka; H. Baltes

• Publisher: Elsevier Science
• Year: 1992
• Tongue: English
• Weight: 900 KB
• Volume: 6
• Category: Article
• ISSN: 0925-4005
• DOI: 10.1016/0925-4005(92)80050-8

✦ Synopsis

We report the fabrication, characterization and modelling of an integrated thermoresistive microbridge gas-flow sensor. It is produced using industrial standard CMOS technology followed by a single maskless post-processing etching step. The sensor principle consists in measuring flow-induced temperature modulations on a heated microbridge by means of integrated polysilicon thermoresistors. Typical values of the flow sensitivity are about 2.5 mV/(m/s) in the linear range. For a quantitative description of the sensor function, an analytical two-dimensional model has been formulated, which in particular takes into account the heat-exchange mechanism between sensor and gas along the surface of the sensor element. We obtain analytical expressions for the output signal resulting from the gas flow; these fit the measured sensor response and, thus, may be used to optimize the sensor design.