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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 ...

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.