Advances in pulsed-laser-deposited AIN thin films for high-temperature capping, device passivation, and piezoelectric-based RF MEMS/NEMS resonator applications

Abstract

In this paper we report recent advances in pulsed-laser-deposited AlN thin films for high-temperature capping of SiC, passivation of SiC-based devices, and fabrication of a piezoelectric MEMS/NEMS resonator on Pt-metallized SiO 2 /Si. The AlN films grown using the reactive laser ablation technique were found to be highly stoichiometric, dense with an optical band gap of 6.2 eV, and with a surface smoothness of less than 1 nm. A low-temperature buffer-layer approach was used to reduce the lattice and thermal mismatch strains. The dependence of the quality of AlN thin films and its characteristics as a function of processing parameters are discussed. Due to high crystallinity, near-perfect stoichiometry, and high packing density, pulsed-laser-deposited AlN thin films show a tendency to withstand high temperatures up to 1600°C, and which enables it to be used as an anneal capping layer for SiC wafers for removing ion-implantation damage and dopant activation. The laser-deposited AlN thin films show conformal coverage on SiC-based devices and exhibit an electrical break-down strength of 1.66 MV/cm up to 350°C when used as an insulator in Ni/AlN/SiC metal-insulator-semiconductor (MIS) devices. Pulsed laser deposition (PLD) AlN films grown on Pt/ SiO 2 /Si (100) substrates for radio-frequency microelectrical and mechanical systems and nanoelectrical and mechanical systems (MEMS and NEMS) demonstrated resonators having high Q values ranging from 8,000 to 17,000 in the frequency range of 2.5-0.45 MHz. AlN thin films were characterized by x-ray diffraction, Rutherford backscattering spectrometry (in normal and oxygen resonance mode), atomic force microscopy, ultraviolet (UV)-visible spectroscopy, and scanning electron microscopy. Applications exploiting characteristics of high bandgap, high bond strength, excellent piezoelectric characteristics, extremely high chemical inertness, high electrical resistivity, high breakdown strength, and high thermal stability of the pulsed-laser-deposited thin films have been discussed in the context of emerging developments of SiC power devices, for high-temperature electronics, and for radio frequency (RF) MEMS.

Tactile multisensing on flexible aluminum nitride

“…Among available deposition techniques, 33,34 reactive sputtering is characterized by good crystal quality at moderate deposition temperature, which is compatible with CMOS technologies and with some organic substrates. 23 The structure and crystalline state of the film are analyzed by X-ray diffraction (XRD).…”

Crystalline structure effect on the performance of flexible ZnO/polyimide surface acoustic wave devices

“…1,2 Great efforts have been made to develop various flexible electronic devices and systems such as displays, 3 eyeball camera, 4 memory, 5 lithium-ion batteries, 6 and transistor and circuits. 7 Attempts have also been made to fabricate microsystems on flexible substrates to deliver unique functions that electronic devices are lacking, including micromachined infrared bolometers, 8 piezoelectric actuators, 9 thin film bulk acoustic wave resonators, 10 piezoelectric pressure sensors, 11 and micro-fluidics.…”

Growth direction modulation and diameter-dependent mobility in InN nanowires

“…Several different catalysts including Au, Ni, Cu and Co were used for growth, but only Au was found to result in high-quality NW growth. Two separate quartz tubes were used to carry NH 3 and N 2 (carrying In vapor) to prevent In vapors from prereacting with NH 3 and hindering NW growth. The growth was performed for 30 min at a temperature range of 650-700…”