Low temperature piezoelectric aluminum nitride thin film

Polycrystalline Aluminum Nitride (AIN) films were deposited on Si(100), Al/Si(100), and Al/SiO2/Si substrates by reactive Direct Current (DC) magnetron sputtering of an Al target, under different conditions of substrate temperature, pressure, N-2/N-2 + Ar ratio. The film properties were investigated by X-Ray Diffraction (XRD), scanning electron microscopy (SEM) and:atomic force microscopy (AFM). Deposition rates in the range of 1.2 to 1.8 mum/h were obtained, the film grain size was around 40nm. To fabricate test structures, wet chemical etching was developed to etch AlN with a good selectivity respect to: Al and Si. Visual aspect and surface roughness show that the maximum temperature must be less than 300 degreesC. X-Ray Diffraction together with dielectric constant measurement show that films are better oriented on Si(100) than on Al/Si(100). epsilon (T)(33) (T: free displacement) = 9.5 to 11, E-br = 200 to 500V/mum, piezoelectric First results give relative dielectric constant effect, good crystal orientation. Membranes were also fabricated using deep reactive ion etching plasma (DRIE), to characterize the film and to fabricate MEMS sensors and actuators, and acoustic wave devices.