A CMOS MEMS Pirani vacuum gauge with complementary bump heat sink and cavity heater

A novel CMOS-MEMS Pirani vacuum gauge with complementary bump heat-sink and cavity heater design has been proposed and demonstrated. This design using CMOS-MEMS process to offer the following advantages for Pirani gauge: (1) The bump heat-sink vertical integrates with cavity heater increases the dynamic range and sensitivity without changing device footprint size, (2) The cavity in heater reduces the thermal mass for low-power operation, and (3) Easy integration with packaged CMOS-MEMS devices for pressure monitoring [1]. The design is implemented using the standard TSMC 0.18μm 1P6M CMOS process. A 120μm×120μm die size with 0.53μm sensing gap is demonstrated. Measurement indicates the gauge has sensing range 0.3-100torr with sensitivity of 1.53×10⁴(K/W)/torr. The power consumption is 67μW for 1% resistance change. In comparison, the gauge with typical heat-sink/heater design has sensing range 1-100torr with sensitivity of 0.99×10⁴(K/W)/torr and power consumption of 119μW.