ABSTRACT
This chapter describes the mechanical design of the sensing element in MEMS silicon oscillating accelerometers (SOA). It focuses on the micro lever structure in the SOA, analyses the micro lever mechanism, and derives the amplification factor of the micro lever and the system amplification factor with the consideration of the effect from the support beams of the sensing element. The chapter describes the two major error sources that impact the SOA performance, e.g. thermal sensitivity and stiffness nonlinearity and discusses the sensitivity of the bias to temperature and nonlinearity stiffness of the Double-Ended Tuning Folks (DETF) resonator. The SOA dies are fabricated using a bulk silicon-on-insulator (SOI) process and a wafer-level vacuum packaging compatible with the SOI process. Then the SOI wafer and the substrate wafer are bonded by a silicon direct bond (SDB). The thickness of the SOI device layer is chosen such that it will match the desired proof mass thickness, typically 60 to 80 µm.
