CMOS compatible 3D flow and thermal sensors in SOI technology

Three-dimensional (3D) self-assembled microstructures are employed in various applications ranging from isolated inductors to tunable capacitors or micro-mirrors. In this article, we present interdigitated capacitors for flow and thermal sensing and circular-shaped bolometers for thermal applications, both based on a one-mask CMOS compatible silicon-on-insulator (SOI) process. We obtained a detection range of 0 to 20 m/s for flow with a variation of 450 MHz in resonance frequency or 9 fF in capacitance for a change of one meter per second and a detection range of 20 to 320deg C with a variation of 600 MHz in resonance frequency for a change of 10deg C. These flow and thermal sensors were also studied from a theoretical point of view simulating the capacitive transducer using finite element softwares which agreed well with measurements