Thin film bulk acoustic resonators formed by sputter deposition of piezoelectric films of aluminum nitride on silicon substrates offer an attractive approach to monolithic integration of high Q passive circuit elements with active devices. Such resonators could provide low cost, high performance filters for the steadily growing numbers of consumer wireless communication devices. Fabrication of these resonators requires a well characterized low temperature deposition process for aluminum nitride. This material has been studied for use in sensors and actuators, as well as acoustic wave devices. Radio frequency reactive magnetron sputtering produces high quality films. The deposition rate is too slow to be practical for many applications, however for high frequency resonators operating above 1 GHz the film thickness and deposition time is more reasonable. This work describes aluminum nitride films deposited by radio frequency reactive magnetron sputtering, using a Box-Behnken experimental design. Factors included power from 2 to 6 W/cm@super 2@, pressure from 1 to 1.6 Pa, and N@sub 2@ flow from 50% to 100% of the total flow. Measured results include X-ray diffraction spectra and measurements of piezoelectric coefficients. X-ray diffraction measurements indicate highly (002) c-axis oriented films. Piezoelectric coefficients were measured by depositing aluminum nitride capacitors on silicon beams and measuring charge generation as each beam was deflected a known distance. These results provide parameters for films that enable accurate modeling and design of high frequency thin film bulk acoustic wave resonators.