Investigation of residual stress and its effects on the vibrational characteristics of piezoelectric-based multilayered microdiaphragms

Abstract

In this study, residual stress influences on the vibrational behavior of piezoelectric circular microdiaphragm-based biosensors are investigated theoretically and experimentally. The piezoelectric microdiaphragm was first fabricated by combining sol-gel PZT thin film and MEMS technology. The stress measurements by the wafer curvature method and the micro-Raman technique demonstrate that high tensile stresses are generated in the upper films (Pt/PZT/Pt), while the silicon oxide layer experiences a compressive stress. After backside etching of the microdiaphragm, the suspended membrane method was used to measure the average stress and equivalent Young's modulus of the diaphragm, which were 96 MPa and 106.4 GPa, respectively. The dynamic behavior of the fabricated sensor under this stress was then investigated. A comprehensive mechanics model based on vibration modes is presented and the natural frequencies of the diaphragm are obtained. A nondimensional tension parameter is defined, and effects of this parameter on the resonant frequency of the diaphragm are presented. It was concluded that both flexural rigidity and tension contribute to the resonant frequency of the diaphragm sensor. Finally, the resonant frequencies of the fabricated sensor were measured by impedance analysis and laser vibrometry techniques. These frequencies were compared with their theoretical counterparts and a good agreement was observed.

Aluminum Nitride Ultrasonic Air-Coupled Actuator

“…The diaphragm mechanical model is used to calculate the volume displacement in (20). The equivalent circuit representation of the two-port model is shown in Fig.…”

“…The authors reported two diaphragm designs with diameters of 1.2 and 1.42 mm and a thickness of 15 μm. The responses [20].…”

Biosensors Based on Sol–Gel-Derived Materials

“…This is a specialized application of the Quartz crystal microbalance as a biosensor. 225 Recently, microdiaphragm piezoelectric-based biosensors have been successfully applied as a biological diagnostic tool in air and liquid media. 226 Thermometric-and magnetic-based sol-gel biosensors are seldom being reported and very few publications could be found in Web of Science.…”

Digital reflection holography based systems development for MEMS testing

“…The diaphragm was fabricated by bonding a piezoelectric plate onto a SOI (silicon on insulator) wafer with 20μm thick device layer [12]. The thickness of the piezoelectric layer was thinned down to about 40μm by using chemical/mechanical polish.…”