AlN films were prepared with a microwave plasma enhanced chemical vapor deposition reactor working at different process temperatures in order to obtain polycrystalline aOE (c) 0001 > oriented films for piezoelectric applications. The films developed were characterized in terms of microstructure, composition, and mechanical properties. Crystalline development and a single orientation were obtained at high temperatures, where at the same time an increase in mechanical intrinsic stresses was observed. Well crystallized aOE (c) 0001 > films were obtained at temperature as low as 500 A degrees C. Furthermore, the evolution of microstructure with thickness at higher temperatures showed a single aOE (c) 0001 > orientation with progressive increase of the texture as the thickness increased. This fact was related with changes in the observed microstructure along the film z-axis, evaluated by high resolution transmission electronic microscopy and selected area electron diffraction. Although orientation dispersion of these films, evidenced by the rocking curves FWHM, remained relatively high (> 9A degrees), they can be regarded as promising for piezoelectric applications. Annealing tests conducted at relatively high temperatures with films deposited at low temperature indicated that thermal effects have only a major effect during the film growth for the temperature values employed.