A low cross-axis sensitivity piezoresistive accelerometer fabricated by masked-maskless wet etching

The paper focuses on the design, simulation, fabrication and experiment of a low cross-axis sensitivity piezoresistive accelerometer fabricated by masked-maskless wet etching in iodine-supersaturated KOH solution. The piezoresistive accelerometer consists of a proof mass, eight supporting beams and four sensing beams. The sensing beams are located at the top surface of silicon chips in order to pattern piezoresistive resistors and metal lines. A boron-diffused piezoresistive Wheatstone bridge is located at the frame-side end of a sensing beam to detect the strain. The gravity center of the proof mass lies within the neutral plane of supporting beams to minimize the rotation of the proof mass under in-plane acceleration. Compared with accelerometer of which the supporting beams located at the surface of chips, the rotating angle of the newly designed sensor under in-plane acceleration is reduced by 98.91%. Preliminary experimental results show that the cross-axis sensitivity under X and Y acceleration is 1.67% and 0.82%, respectively.