High sensitive, linear and thermostable pressure sensor utilizing bipolar junction transistor for 5 kPa

Mikhail Basov

doi:10.1088/1402-4896/abf536

Abstract

Research of pressure sensor chip utilizing novel electrical circuit with bipolar-junction transistor-based (BJT) piezosensitive differential amplifier with negative feedback loop (PDA-NFL) for 5 kPa differential range was done. The significant advantages of developed chip PDA-NFL in the comparative analysis of advanced pressure sensor analogs, which are using the Wheatstone piezoresistive bridge, are clearly shown. The experimental results prove that pressure sensor chip PDA-NFL with 4.0 × 4.0 mm2 chip area has sensitivity S = 11.2 ± 1.8 mV/V/kPa with nonlinearity of 2KNLback = 0.11 ± 0.09%/FS (pressure is applied from the back side of pressure sensor chip) and 2KNLtop = 0.18 ± 0.09%/FS (pressure is applied from the top side of pressure sensor chip). All temperature characteristics have low errors, because the precision elements balance of PDA-NFL electric circuit was used. Additionally, the burst pressure is 80 times higher than the working range.

Highlights

Microelectromechanical system (MEMS) piezoresistive pressure sensors with Wheatstone bridge electrical circuit are the most widely used elements for pressure analysis in many industrial and research fields
The experimental results prove that pressure sensor chip piezosensitive differential amplifier with negative feedback loop (PDA-NFL) with 4.0x4.0 mm2 chip area has sensitivity S = 11.2 ± 1.8 mV/V/kPa with nonlinearity of 2KNLback = 0.11 ± 0.09 %/FS and 2KNLtop = 0.18 ± 0.09 %/FS
It is important to note that the pressure sensor PDA-NFL combination of selected electrical circuit and mechanical part with supmembrane oxide (SO) allows to achieve fairly low temperature dependence

Summary

Introduction

Microelectromechanical system (MEMS) piezoresistive pressure sensors with Wheatstone bridge electrical circuit are the most widely used elements for pressure analysis in many industrial and research fields. The thinned membrane part with thickness of several microns, where maximum mechanical stresses (MS) are created, is most susceptible to residual MS influence from: 1) SiO2 and Si3N4 layers, especially in case of their step distribution on top silicon surface [3,4], 2) metallization with significantly different coefficient of thermal expansion (CTE) [3,4,5,6], 3) the back surface roughness after etching [7], 4) types and methods of packaging [4,8,9,10,11,12] These facts lead to error increase for nonlinearity, temperature characteristics and larger scatter of output parameters The efficiency of PDA-NFL circuit has already been successfully demonstrated for sensors of medium pressure range for 60 kPa [21,22]

PDA-NFL circuit analysis

Output characteristics

Findings

Conclusion