An integrated thermo-capacitive type MOS flow sensor

A prototype of a new thermo-capacitive integrated flow sensor consisting of a floating-gate MOS transistor has been developed. Tantalum pentoxide is the dielectric material between the top (control) gate and the floating-gate. The temperature dependence of the dielectric constant is about 375 ppm//spl deg/C. The process flow is compatible with standard MOS process and augmented to include a capacitor module and bulk micromachining. The output voltage change at the flow velocity of 20 m/s is about 26 mV at 57 mW of heater power. The sensitivity in the 0-4 m/s flow velocity region is 4.25 mV(m/s)/sup -1/.