A novel low pressure sensor with fin-structures

A fin type silicon-based Pirani vacuum gauge and its measurement methodology are first introduced. It provides a wide pressure measurement range from 0.1 torr to 760 torr with device size less than 300 × 300μm². This vacuum gauge can be monolithically integrated with motion sensors or resonators using the same fabrication processes, and thus further be exploited to monitor the cavity pressure where above devices operate. This study demonstrated a fin type structure of 2μm gap and with heat sinks all around. By using this structure, the thermal conduction through air can be greatly improved comparing to a single beam structure. Moreover, it provides a strong rigidity to reduce process imperfections, such as stress imbalanced and stiction risks. The testing setup is a standard I-V testing which can be simply implemented. In-addition, a second-order term extraction from R-V curve is introduced to remove zero-order term variation, such as the resistance variation within wafer and between wafers. This device can potentially be designed as altimeters, hygrometers, pressure sensors or their combination.