The design of a novel structural four-beams-bossed-membrane (FBBM) piezoresistive pressure sensor

This paper presents a novel structural piezoresistive pressure sensor with four-beams-bossed-membrane (FBBM) that consisted of four short beams and a central mass to measure micro-pressure. In this work, the model design, dimensions optimization, and main fabrication processes are involved. The finite element analysis (FEA) is used to study the stress distribution of sensitive elements and deflection of membrane. Subsequently, the relationships between the structural dimensions and the mechanical performance are deduced. Finally, curve fittings of the mechanical stress and deflection based on simulation results are performed to establish a series of equations of the sensor. According to the optimization processes, the FBBM structural membrane dimensions are ultimately determined. The main fabrication processes of the pressure sensor chip based on MEMS bulk-micromachining and anodic bonding technology are also introduced. The results show that a high sensitivity of 4.71 mV/V/kPa and a low pressure nonlinearity of 0.75% FSS can be achieved, indicating that this novel structure is a proper choice for pressure measurements less than 5 kPa.