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A device for acoustic particle manipulation in the 40 MHz range for continuous-flow operation in a 50 μm wide PDMS channel has been evaluated. Unidirectional interdigital transducers on a Y-cut Z-propagation lithium nixobate wafer were used to excite a surface acoustic wave that generated an acoustic standing wave inside the microfluidic channel. It was shown that particle alignment nodes with different inter-node spacing could be obtained, depending on device design and driving frequency. The observed inter-node spacing differed from the standard half-wavelength inter-node spacing generally employed in bulk acoustic transducer excited resonant systems. This effect and the related issue of acoustic node positions relative the channel walls, which is fundamental for most continuous flow particle manipulation operations in channels, was evaluated in measurements and simulations. Specific applications of particle separation and alignment where these systems can offer benefits relative state-of the art designs were identified.

A shear mode AlN solidly mounted resonator (SMR) microfluidic sensor system was fabricated and characterized. The AlN SMR fabrication process is fully IC compatible and uses reactive sputtering to ...

Oscillators based on AlN thin-film bulk acoustic resonators are designed, fabricated and measured. The circuits are realised as silicon-on-silicon multichip modules where SiGe transistors are flip-chip mounted on a novel carrier substrate which includes monolithically integrated resonators and passive components. The paper describes the development and processing of the carrier substrate and resonators, as well as the development of the oscillator circuits.

A new design of a solidly mounted resonator (SMR) that utilizes an all-metal Bragg reflector eliminating thus the need for a bottom electrode is proposed. In this configuration, the role of the bottom electrode is taken by the Bragg reflector rendering the resonator “combined electrode-Bragg reflector SMR”. The main advantages of the proposed design are the substantially reduced electrode resistance (and hence higher Q), the utilization of the full piezoelectric coupling at high frequencies as well as expected improvement in power handling capabilities due to lower dissipation and improved heat conductivity. Resonators with the classical and the new design have been fabricated and evaluated. The measurements indicate that indeed the resonators with the new design demonstrate improved performance.

Highly c-oriented aluminum nitride (AlN) thin piezoelectric films have been grown by pulsed direct-current (DC) magnetron reactive sputter deposition. The films were deposited at room temperature and had a typical full width half maximum (FWHM) value of the (0 0 2) rocking curve of around 2 degrees. Resonant devices in thin film plates having surface acoustic wave (SAW) based designs were fabricated by means of low resolution photolithography. The devices were designed to operate with the fast Rayleigh and Lamb modes respectively. Both types of devices exhibited propagation velocities in excess of 10,000 m/s and sufficient electromechanical couplings. The device measurements illustrate the big potential of these modes for the development of low cost IC compatible electroacoustic devices in the lower GHz range. The basic properties of the modes studied are discussed in a comparative manner. Potential commercial applications are also outlined.

Semiconducting boron doped single-crystal CVD diamond has been patterned using aluminum masks and an inductively coupled plasma (ICP) etch system. For comparison insulating HPHT diamond samples were also patterned using the same process. Diamond etch rates above 200 nm/min were obtained with an O2/Ar discharge for a gas pressure of 2.5 mTorr using 600 W RF power. We have accomplished the fabrication of structures with a minimum feature size of 1 μm with vertical sidewalls in both CVD and HPHT diamond. The ICP etching produced smooth surfaces with a typical root-mean-square surface roughness of 3 nm. The dependence of etch rate on bias voltage was somewhat different for the two types of diamond. However, for all samples both the etch rate and anisotropy were found to improve with increasing bias voltage.

The work in question addresses the issue of continuous flow particle manipulation in liquid media with particular emphasis on particles with micron and sub-micron dimensions. The subject is of significant relevance for a range of bio-technological applications and in particular for lab-on-chip ones. Particle manipulation utilizing Interface Acoustic Waves (IAW) is proposed for the first time. Manipulation of submicron sized particles is successfully demonstrated in a streaming free regime.

A 2 GHz oscillator based on a solidly mounted AlN Thin-Film Bulk Acoustic Resonator (TFBAR) is reported. The oscillator is realised as a silicon-on-silicon Multi-Chip Module (MCM) where all passive elements, including the TFBAR, are monolithically integrated on a High-Resistivity Silicon (HRS) carrier. SiGe transistors are flipchip mounted on the MCM carrier. Measurements of the oscillators reveal a best phase-noise of −125 dBc/Hz at 100 kHz offset.

A solidly mounted resonator (SMR) that has a bottom electrode with a thickness of one quarter of the acoustic wavelength at resonance has been fabricated. In this configuration, the bottom electrode is uncoupled from the resonance cavity of the SMR rendering it "electrodeless". The uncoupling of the bottom electrode is confirmed both by simulation with the one-dimensional Nowotny-Benes model, and experimentally by comparison with a SMR with a standard thin bottom electrode. The "electrodeless" SMR exhibits reduced series resistance Rs and improved device Q. A solidly mounted resonator (SMR) consists of a piezoelectric thin film, sandwiched between two thin electrodes and is fabricated directly onto a carrier substrate. The resonance frequency of the resonator is determined by the total acoustic thickness of the resonance cavity defined by the piezo- layer and the electrodes. To acoustically isolate the resonator from the substrate, it is fabricated on top of a classical acoustic mirror, here called Bragg reflector. The Bragg reflector consists of a sequence of a quarter wavelength layers of low and high acoustic impedance, respectively (1). In this work the bottom electrode is eliminated from the acoustic cavity of the SMR by incorporating it into the Bragg reflector instead. Choosing a low impedance conducting material as the topmost layer in the reflector, eliminates completely the need for a bottom electrode and brings, in return, a number of significant benefits. Most notably, the ohmic resistance of the resonator is reduced, since the reflector layer is much thicker than the original electrode. Alternatively, the whole stack could be made of conducting materials to reduce ohmic resistance even further. The excitation efficiency is also increased since the bottom electrode, which is piezoelectrically inactive, is no longer part of the resonance cavity. Furthermore, if the acoustic reflector layers are made up entirely of metals, an efficient heat path through the mirror is established, which reduces thermal resistance and should improve the power handling capabilities of the device. By the same token, the top electrode can also be eliminated from the resonance cavity, achieving total acoustic isolation of the resonator from its surrounding in addition to doubling the gains described above. In the present study, a one-port SMR, based on reactively sputtered, c-axis oriented aluminum nitride (AlN) was fabricated according to the schematic in Fig.1. The SMR was fabricated such that the bottom electrode is incorporated into the Bragg reflector. Aluminum was used for the top electrode. The acoustic mirror, underneath the resonators were made of a quarter wavelength aluminum (Al) and molybdenum (Mo) layers, providing electrical contact underneath the piezo-layer. The devices were electroacoustically characterized and the results compared with a thin electrode SMR.

This paper describes the design and measurement of a 2 GHz oscillator based on a Solidly Mounted Thin Film Bulk Acoustic wave Resonator (SM TFBAR). The circuitry is patterned on an alumina substrate on which the transistors and capacitors are soldered. The SM TFBAR chip is integrated by means of wirebonding. The measured oscillator centre frequency is about 2.038 GHz with an output power of 0 dBm.

Thin film bulk acoustic wave resonators (FBAR), solidly mounted resonators (SMR), and thin film plate acoustic resonators (FPAR) based on piezoelectric aluminum nitride (AlN) are all attractive candidates for monolithically integrated filters, sensors and oscillators operating in the gigahertz frequency range. This work aims at performing a systematic study of the DC electric field sensitivity of FBAR, SMR and FPAR devices fabricated with the same technology and utilizing membranes with comparable thicknesses. Further, the results are presented in terms of the electric field coefficient of frequency (ECF) which is supposed to be a thickness independent value under certain assumptions. The ECF coefficients of the devices under study were extracted from the frequency shift in the recorded frequency spectra. No hysteresis effects are observed during the measurements. Finally, a novel frequency tuning concept for FPARs based on biasing the distributed reflectors, thus shifting the frequency stopband edges, is reported. The effects studied can be utilized for active temperature compensation circuits as well as for static voltage sensors

This letter discusses the design of thickness shear mode thin-film bulk acoustic resonator (FBAR) sensor array for in liquid operation with respect to minimizing the observed Q-degradation and crosstalk.

Particle manipulation utilizing interface acoustic waves (IAWs) is proposed for the first time. An IAW-based manipulation system has been designed, micromachined and tested. This work addresses the issue of particle manipulation in microfluidic channels with particular emphasis on particles with submicron dimensions. The subject is of significant relevance for a range of bio-technological applications and in particular for lab-on-chip ones. Submicron particle manipulation in continuous flow has been demonstrated.

Compositional analysis of aluminium oxy-nitride (AlON) films deposited by reactive magnetron sputtering was performed using time-of-flight elastic recoil detection analysis (ToF-ERDA) and X-ray photoelectron spectroscopy (XPS) with sputter profiling. The composition profiles of the films depend on deposition conditions. The benefits of the different analytical methods are discussed and comparison of the profiles is performed. Conversion of the depth scale from XPS sputter time to a nm scale is implemented and the ToF-ERDA profile fitted. Densities of the deposited AlON films are calculated indicating differing film quality in agreement with the composition profile extracted.

For use in thin film electroacoustic (TEA) technology a few hundred nanometre thick nickel silicide (NiSi) electrode would need to be fabricated. A complete fabrication process for the formation of over 200 nm thick silicide films has been optimised for use as an electroacoustic electrode. Optimisation of silicidation temperature and identification of the mono phase of silicide is demonstrated. Thick electrodes are formed by depositing multilayers of silicon and nickel pairs onto silicon (Si) substrates before rapid thermal annealing. The numbers of multilayers and relative material thicknesses are optimized for both surface roughness and electrical resistivity. The growth of textured aluminium nitride (AlN) has been investigated on the optimised surfaces.