Piezoelectric AlN thin films were deposited on Silicon substrates by triode reactive sputtering. The variation of residual stress versus bias voltage on the substrate was investigated. A compressive stress was always observed with a maximum value for a negative substrate bias of 50 V. For higher negative bias voltage values, the compressive stress decreases. X-ray diffraction measurements showed two kinds of growth orientation. First, without bias voltage, films are well crystallized and (002) oriented. Second, with bias voltage, the (002) orientation disappears and a small peak appears (situated in the 2 theta=32 degrees-33 degrees range) which can be attributed to (100) orientation. Finally, the influence of compressive stress and ion bombardment on the change of orientation is discussed. (c) 2007 Elsevier B.V. All rights reserved.