Piezoresistive accelerometer with overload protection and low cross-sensitivity

• Published in: Sensors and actuators. A. Physical. 1993, Vol.39 (3), p.201-207
• Main Authors: Crazzolara, H., Flach, G., von Miinch, W.
• Format: Article
• Language: English
• Subjects: Exact sciences and technology; Measurements common to several branches of physics and astronomy; Metrology, measurements and laboratory procedures; Physics; Velocity, acceleration and rotation
• ISSN: 0924-4247; 1873-3069
• DOI: 10.1016/0924-4247(93)80220-B

A piezoresistive silicon bridge-type accelerometer is described. The application of a standard bipolar process allows the mechanical structure to be realized by anisotropic wet etching in KOH with an electrochemical etchstop at selectively diffused n-type layers. A novel glass-bonding technology offers complete encapsulation of the sensor with silicon top and bottom caps, including wafer-level assembly and simultaneous overload protection. Optimization of the mechanical structure by finite-element modelling (FEM) with respect to the resonance frequency results in the application of transverse piezoresistors with excellent cross-sensitivity compensation. The sensor features a sensitivity of 40 μV/N g with a non-linearity of less than 0.5% up to 350 g, first resonance frequency of about 5 kHz, and cross-sensitivity in lateral directions of less than 0.2% with an overall chip size of 3.7 × 3.7 × 1.0 mm 3.