This work reports on the first demonstration of frequency tuning and intrinsic polarization switching film bulk acoustic resonators (FBARs), based sputtered AlScN piezoelectric thin films with Sc/(Al + Sc) ratio approx. 30%. A box-like ferroelectric hysteresis behavior 900 nm-thick Al <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.7</sub> Sc xmlns:xlink="http://www.w3.org/1999/xlink">0.3</sub> N is obtained, showing a coercive electric field...

Elastic constants c <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> , xmlns:xlink="http://www.w3.org/1999/xlink">12</sub> and xmlns:xlink="http://www.w3.org/1999/xlink">44</sub> of degenerately doped silicon are studied experimentally as a function the doping level temperature. First-and second-order temperature coefficients elastic extracted from measured resonance frequencies set MEMS resonators fabricated on seven different wafers...

Passive temperature compensation of silicon MEMS resonators based on heavy n- and p-type doping is studied. Resonators are fabricated utilizing with phosphorus level 5·10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">19</sup> cm xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> boron levels 2 · 10 xmlns:xlink="http://www.w3.org/1999/xlink">20</sup> , the latter being stress compensated germanium. The behavior resonance frequencies Lamé...

Scandium-alloying of aluminum nitride (AlScN) enhances the piezoelectric properties material and increases performance microelectromechanical systems (MEMS). However, this enhancement is caused by destabilization wurtzite phase so far stability AlScN thin films has not been sufficiently studied. Stability especially important for devices because changes to film microstructure or residual stress can lead drastic in device behavior. The investigated annealing sputtered characterizing resulting...

Resonating piezoelectric devices, such as aluminum nitride (AlN) micromachined ultrasonic transducers (PMUTs), display superior performance to previous generations of resonating microelectromechanical systems (MEMS). However, the quality thin film can greatly impact operating characteristics, resonant frequency. Several AlN PMUT devices fabricated on same silicon wafer exhibited a range resonance frequencies (400-600 kHz), indicating that there is nonuniformity across processed wafer. likely...

We report on the anisotropic wet etching of sputtered AlN and Sc0.2Al0.8N thin films. With tetramethyl ammonium hydroxide at 80 °C, etch rates along c-axis were 330 30 nm/s for Sc0.2Al0.8N, respectively. Although was anisotropic, significant lateral below mask occurred, perpendicular to c-axis. a 1 µm film, it could be up 1800 nm. studied with molybdenum, SiO2, SiNx TiO2 masks, found leading cause modification or surface caused by ion bombardment oxidation ambient air. The reduced optimizing...

The first- and second-order temperature coefficients the total temperature-induced frequency deviation of degenerately n-type-doped silicon resonators are modeled. Modeling is based on finite element modelling-based sensitivity analysis various resonator geometries combined with experimental results doping-dependent elastic constants silicon. covers a doping range from 2.4 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">17</sup> to 7.5...

Zinc-oxide-based thin-film bulk acoustic wave (BAW) resonators operating at 932 MHz are investigated with respect to variation of dimensions a boundary frame spurious mode suppression structure. A plate dispersion-based semi-2-D model and 2-D finite element method used predict the eigenmode spectrum explain detailed behavior. The models show how changes eigenmodes their coupling driving electrical field via modification mechanical condition leads emergence flat-amplitude piston modes. Narrow...

Scandium-alloyed aluminum nitride (AlScN) is a potential material for micro-electromechanical systems because of its unique advantages, such as strong piezoelectric effect and high thermal stability. However, issues related to stability interaction with other materials in multilayer require investigation. The formation new phases at the interface between piezomaterial electrode can lead device failure. In this study, structures Si substrate/AlN/Ti-Mo/Al <sub...

We report on the design, fabrication and characterization of piezoelectrically actuated single-crystal silicon plate resonators vibrating mainly in their bulk acoustic wave modes. Two resonator types are presented: one operates square extensional mode at 26 MHz with Q~18000 motional resistance R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">m</sub> ~0.240 kOmega, while other features a resonance 22 Q~51000 ~1.5 kOmega. The characterized...

Acoustically coupled thin-film bulk acoustic wave resonator filters, in which the coupling takes place mechanically lateral direction between closely-spaced narrow resonators, are a promising approach to passband filtering at gigahertz frequencies. In this paper, filters with interdigital electrode structures studied. Electrode number, width, and gap width varied. The resonators solidly mounted, having an mirror isolating from Si substrate providing means engineer dispersion properties of...

We model the temperature coefficients of resonance modes degenerately n-type doped silicon resonators. By combining results from FEM-based sensitivity analysis and modelling elastic constants with free carrier theory we are able to identify classes that can be compensated via doping. These include bulk such as width/length extensional a beam, Lamé/square plate resonator, well flexural torsional modes. Our show virtually all practical importance reach zero TCF when resonator is aligned...

Aluminum nitride piezo MEMS mirror for laser beam scanning in automotive LIDAR applications was developed. The has an optical aperture of 4 mm, chip size 6.75×6.75×2mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> , and frequency 1.6 kHz. A tilt angle +/− 15 degrees corresponding to 30-degree scan is achieved with a low drive voltage ~ 2 V <inf xmlns:xlink="http://www.w3.org/1999/xlink">pp</inf> .

The dispersion curves of Lamb-wave modes propagating along a multilayer structure are important for the operation thin-film bulk acoustic wave (BAW) devices. For instance, behavior side resonances that may contaminate electrical response BAW resonator depends on relation layer stack. Because materials parameters (and thicknesses) layers in structure, measurement provides tool determining thin films. We have determined through measuring mechanical displacement profiles over top electrode at...

Beam-drift based flow measurement technique requires frequency matched ultrasound transmitters and receivers for determining the rate. Aluminum nitride (AlN) piezoelectric micromachined ultrasonic transducers (PMUTs) suitable such an application have been designed fabricated. The bottom electrode is in way that it reduces stray capacitances, without degrading properties of AlN layer deposited on it. Frequency matching within a PMUT array PMUTs fabricated across wafer are challenging due to...

Acoustic wave fields both within the active electrode area of a solidly mounted 1.8 GHz bulk acoustic resonator, and around it in surrounding region, are measured using heterodyne laser interferometer. Plate-wave dispersion diagrams for regions extracted from measurement data. The experimental data reveal cutoff frequencies vibration modes region and, therefore, energy trapping range resonator can readily be determined. properties together with abruptly diminishing amplitude curves signal...

A heterodyne laser interferometer is used to study acoustic wave fields excited in a 1.8 GHz AlN thin film bulk resonator. The electrical response of the resonator exhibits strong thickness resonance onto which spurious modes, caused by lateral standing plate waves, are superposed. Optical measurements extract dispersion curves laterally propagating waves responsible for responses. discrete eigenmode spectrum due finite dimensions observed. An equivalent circuit model multimode fitted...

A 2-D model is developed for calculating lateral acoustical coupling between adjacent thin film BAW resonators forming an electrical N-port. The based on solution and superposition of eigenmodes eigenfrequencies in a structure consisting regions with known plate wave dispersion properties. Mechanical response the device are calculated as according to voltage drive at one port time while extracting current induced other ports, leading full Y-parameter description device. Exemplary cases...

We report on the design, fabrication and measurement of 13-MHz piezoelectrically actuated single-crystal silicon beam resonators operating in first length-extensional mode. The transduction mechanism is based an aluminum nitride layer grown top resonator beam. are measured to have a quality factor Q ~ 20000 at p < 1 mbar typical motional resistance R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">m</sub> 3 kOmega. electromechanical eta ~20...

After optimizing for electromechanical coupling coefficient K <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , the main performance improvement in thin film bulk acoustic wave resonators and filters can be achieved by improving Q value, i.e., minimizing losses. In Bragg-reflector-based solidly mounted resonator technology, a significant of has been reflector not only longitudinal wave, intended operation mode, but also shear waves. We...

A heterodyne laser interferometer is used for a detailed study of the acoustic wave fields excited in 932-MHz solidly mounted ZnO thin-film BAW resonator. The sample manufactured on glass substrate, which also allows direct measurement vibration from bottom mirror. Vibration are measured both top resonator and at mirror-substrate interface frequency range 350 to 1200 MHz. Plate dispersion diagrams calculated experimental data cases transmission characteristics mirror determined as function...

This work demonstrates the hysteresis behavior and temperature characterization of an AlScN Film bulk acoustic resonator (FBAR) with ~30% Sc/(Al+Sc) ratio. Operating at ~3 GHz, as-fabricated FBAR exhibits a record high effective electromechanical coupling ( kt <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ) 18% mechanical quality factor Qm) 328. The polarization can be switched from N-polar to Al-polar by using triangular-wave signal...