Finite Element Method on Mass Loading Effect for Gallium Phosphate Surface Acoustic Wave Resonators (original) (raw)
Assembly and interconnection technology for high-temperature bulk acoustic wave resonators
Journal of Sensors and Sensor Systems, 2022
A sensor based on a piezoelectric single crystal enables operation even under harsh environmental conditions. In addition to the sensor element, the packaging technology is crucial for sensor performance. In this paper, a suitable assembly and interconnection technology concept of Ca 3 TaGa 3 Si 2 O 14 (CTGS) resonators for high-temperature applications is presented as a platform for future sensor assemblies. The concept described here has already been functionally tested as a temperature sensor . The concept includes a sapphire base plate, a housing lid, and a spacer made from aluminium oxide (Al 2 O 3 ). The substrate is metallised with platinum manufactured into thin film and thick film technology. The ceramic components are fused with glass solder. The connection of the resonator to the conductive tracks is realised by thermosonic bonding with 25 µm platinum wire. Initially, the stability of the metallisation must be investigated before subsequent electrical testing under high temperature. Diffusion processes play a major role in this temperature range, and the stability of the layer is a necessary condition for subsequent investigations. A suitable set of bonding parameters and the strength of the platinum bonds prior to and after thermal load is analysed. Shear tests are used to evaluate the quality of the ceramic materials fused with glass solder after thermal ageing. The dielectrical properties of sapphire and glass solder such as the isolation resistance, the relative permittivity, and the loss factor at high temperatures are evaluated using interdigital structures. The loss factor is measured on both bare interdigital structures and the samples coated with glass solder to make an estimation about the conductive behaviour up to 1000 • C. A ceramic lid for the sensor housing is attached by a high-temperature stable glass solder. Since platinum conductors are fed through this glass solder connection, the electrical conductivity of the glass solder is characterised at high temperature. Furthermore, the hermeticity of the assemblies is verified by means of helium leakage tests. These investigations are the basis for the implementation of an assembly and interconnection technology that is suitable for reliable operation under extreme temperature conditions. The packaging technology also offers further possibilities for pressure or chemical sensors that can withstand high-temperature loads.
High-Performance Film Bulk Acoustic Wave Pressure and Temperature Sensors
Japanese Journal of Applied Physics, 2007
A film bulk acoustic wave resonator (FBAR)-based sensor for the simultaneous measurement of temperature and pressure with high sensitivity is fabricated and characterized. Temperature or pressure sensing is determined by the change in the series resonant frequency of the FBAR device when exposed to a measurement environment. For temperature sensing, measurement results show a sensitivity of 25.02 ppm/ C, a nonlinearity less than AE0:005% over the measurement range of 10 to 80 C, and a hysteresis within AE0:005% in one temperature cycle. In pressure sensing, measured results show a sensitivity of 336.2 ppm/ bar, a nonlinearity less than AE0:004% over the measurement pressure range of 0 to 2.07 bar, and a hysteresis within AE0:007% in one pressure cycle.
Design of a surface acoustic wave mass sensor in the 100 GHz range
Applied Physics Letters, 2012
A design for photoacoustic mass sensors operating above 100 GHz is proposed. The design is based on impulsive optical excitation of a pseudosurface acoustic wave in a surface phononic crystal with nanometric periodic grating, and on time-resolved extreme ultraviolet detection of the pseudosurface acoustic wave frequency shift upon mass loading the device. The present design opens the path to sensors operating in a frequency range currently unaccessible to electro-acoustical transducers, providing enhanced sensitivity, miniaturization and incorporating time-resolving capability while forgoing the piezoelectric substrate requirement.
Journal of Electronic Materials, 2019
This paper reports the effect of the design parameters of a solidly mounted film bulk acoustic resonator (SMFBAR) for better gas sensing performance. The electrical equivalent circuit of the proposed device has been developed with the help of a Butterworth Van-Dyke (BVD) circuit. The electro-mechanical response of the SMFBAR has been obtained with the help of 3-D finite element method (FEM) analysis. The analytical modeling and FEM simulation results are compared. The physical parameters of the proposed design such as piezoelectric layer material, its thickness, active area of the device and sensing layer thickness affecting the characteristics of the SMFBAR have been investigated in detail. To achieve enhanced sensitivity, the variation of square active area has been analysed with one side dimension ranging from 700 lm to 300 lm. Gas sensing performance of the proposed sensor is tested by exposing toluene gas concentration ranging from 0 ppm to 500 ppm and enhanced sensitivity of 20 kHz/ppm has been achieved and reported. Also, it is reported that the variation in ratio of electrode layer thickness to piezoelectric layer thickness results in improvement of coupling coefficient (k eff 2) up to 7.46%.
Thermal characterization of Surface Acoustic Wave devices
2013
Reliability of micro-electronic devices is one of the most important issues in mobile communication systems and is significantly influenced by the thermal behavior of the components. This study presents different schemes for thermal characterization of a half-section ladder-type Surface Acoustic Wave (SAW) filter which is acoustically passivated with a thick SiO2 layer. Unitarity violation quantifies the entire power loss in the device but is unfeasible regarding correlation to each resonator. The Temperature Coefficient of Frequency (TCF) characterizes thermally induced frequency shifts and has the potential to investigate the resonators' temperatures separately in first order. However, uncertainties arise using this indirect approach as soon as other effects causing a frequency shift play a role. Thermographic techniques such as Infrared Thermography (IRT) and Liquid Crystal Thermography (LCT) serve as direct measurement schemes eliminating inaccuracies inherent to TCF based evaluations and show good agreement with simulation results. Moreover, LCT and IRT provide spatially resolved temperature measurements of the component.
Temperature compensated radio-frequency harmonic bulk acoustic resonators pressure sensors
2010 IEEE International Ultrasonics Symposium, 2010
In this work, we propose a compensated temperature pressure sensor fabricated on compound LiNbO 3 /Quartz/Quartz substrates obtained by Au/Au bonding at room temperature and double face lapping/polishing of LiNbO 3 /Quartz stack and a final gold bonding with a structured Quartz wafer. This paper shows the possibility to obtain device which is intrinsically low sensitive to thermal effects, and even allowing a second order compensation thanks to the Quartz thermal stability Sensitivity of the final sensor to bending moments then is tested and results show pressure sensitivity of such devices.
Spatial sensitivity distribution of surface acoustic wave resonator sensors
2007
Abstract The sensitivity distribution of surface acoustic wave (SAW) resonator sensors is investigated by theoretical and experimental means. It is shown that the sensitivity to mass loading varies strongly across the surface due to the confinement of acoustic energy toward the center of the device. A model is developed for this phenomenon based on the extraction of coupling of modes parameters from a rigorous boundary element method analysis based on a periodic Green's function.
Biosensors and Bioelectronics, 2012
Bulk acoustic wave (BAW) filters have been extensively used in consumer products for mobile communication systems due to their high performance and a standard CMOS compatible integration process. However, a traditional BAW filter generally presents only one frequency transmission band; hence, it cannot meet the demands of multi-mode wireless communication systems. In this work, we propose a radio frequency dual-band filter based on a dual-mode film bulk acoustic resonator (FBAR). The dual-mode FBAR consists of molybdenum electrodes and an aluminum nitride film with a c axis tilt angle, which leads to the coexistence of the longitudinal mode and the shear mode in the resonator. The influence of the tilt angle on the resonant frequency and electromechanical coupling coefficient of the dual-mode FBAR is investigated. Subsequently, the behaviors of the dual-mode FBAR have been emulated by a modified Butterworth-Van Dyke model with two motional branches, which is further used to design and optimize the dual-band filter. The dual-mode FBAR-based filters connected in a ladder configuration present two dual passbands of 43 MHz and 105 MHz, respectively. The developed filters with dual passbands can give an inspiration to the design of BAW devices in modern wireless communications.
Langasite surface acoustic wave gas sensors: modeling and verification
IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, 2000
We report finite element simulations of the effect of conductive sensing layers on the surface wave velocity of langasite substrates. The simulations include both the mechanical and electrical influences of the conducting sensing layer. We show that three-dimensional simulations are necessary because of the out-of-plane displacements of the commonly used (0, 138.5, 26.7) Euler angle. Measurements of the transducer input admittance in reflective delay-line devices yield a value for the electromechanical coupling coefficient that is in good agreement with the threedimensional simulations on bare langasite substrate. The input admittance measurements also show evidence of excitation of an additional wave mode and excess loss due to the finger resistance. The results of these simulations and measurements will be useful in the design of surface acoustic wave gas sensors.