Design optimization and fabrication of a novel structural piezoresistive pressure sensor for micro-pressure measurement

- A novel four-beams-bossed-membrane (FBBM) structural MEMS piezoresistive pressure sensor was proposed.
- A new geometry optimization method of the FBBM structure based on curve fitting and statistic was introduced.
- The relative equations between the performance and dimension variables for accurate design and fabrication were deduced.
- The proposed sensor alleviated the contradiction between sensitivity and linearity.

This paper presents a novel structural piezoresistive pressure sensor with a four-beams-bossed-membrane (FBBM) structure that consisted of four short beams and a central mass to measure micro-pressure. The proposed structure can alleviate the contradiction between sensitivity and linearity to realize the micro measurement with high accuracy. In this study, the design, fabrication and test of the sensor are involved. By utilizing the finite element analysis (FEA) to analyze the stress distribution of sensitive elements and subsequently deducing the relationships between structural dimensions and mechanical performance, the optimization process makes the sensor achieve a higher sensitivity and a lower pressure nonlinearity. Based on the deduced equations, a series of optimized FBBM structure dimensions are ultimately determined. The designed sensor is fabricated on a silicon wafer by using traditional MEMS bulk-micromachining and anodic bonding technology. Experimental results show that the sensor achieves the sensitivity of 4.65 mV/V/kPa and pressure nonlinearity of 0.25% FSS in the operating range of 0-5 kPa at room temperature, indicating that this novel structure sensor can be applied in measuring the absolute micro pressure lower than 5 kPa.