FABRICATION OF ACTIVE THIN FILMS FOR VIBRATION DAMPING IN MEMS DEVICES FOR THE NEXT GENERATION ARMY MUNITION SYSTEMS

Abstract : This research combined continuum mechanics modeling, materials design, materials fabrication/processing, and experimental testing/characterization to promote a materials solution for passive damping of undesirable extrinsic vibrations in microelectromechanical-systems-based devices. Shape memory alloy, nickel titanium (NiTi) thin films were deposited by an in-situ reactive DC magnetron sputtering process and piezoelectric, barium strontium titanate (Ba0.80Sr0.20TiO3) were fabricated using pulsed laser deposition and metal organic solution deposition techniques. These films were integrated as a bi-layer structure on n+ platinum silicon substrates to form a vibration-damping pedestal module known as active materials. The optimized post deposition annealing temperatures for the shape memory alloy and piezoelectric thin films were determined to be 500 and 750 degrees C, respectively. Crystalline, pinhole-free, and crackfree films of 250-400 nm thickness were fabricated. The surface roughness of the films was around 2.2 nm with average grain size of approximately 50 nm. Cross- sectional microscopy affirmed the dense and uniform microstructure. The bilayer pedestal design concept offers a solution for passive damping.