The authors present a study on the influence of the bias voltages on the preferred orientation and microstructure of helium-doped Ti films. The films were deposited in a vacuum chamber by both direct-current magnetron sputtering and electron-cyclotron-resonance plasma-aided magnetron sputtering (ECR-PMS) methods. The preferred orientation and microstructure of the films were analyzed by x-ray diffraction (XRD) and transmission electron microscopy. They found that the preferred crystal orientation of helium-doped Ti films was controllably varied from (002) to (100) orientation by increasing the bias voltage (i.e., ion bombardment current and energy). The dominant bombardment effect on the orientation was from the Ar ions of the anode sheath in the magnetron sputtering plasma, and He bombardment also showed a slight influence on the orientation transformation at low trapped-helium content in the crystal. The XRD peak broadening of helium-doped Ti films prepared by ECR-PMS is much more serious than for conventional magnetron sputtering even at low helium concentrations. It is believed that asynchronous bombardment from He ions in the ECR plasma area and Ar ions in the deposition plasma during film growth significantly decreases the mobility of Ti adatoms on the surface and enhances the growth of helium-induced defects, thus increasing the crystal disorder and influencing the crystal orientation transformation. On the contrary, the sequential bombardment of He and Ar particles can decrease helium-dissolution produced defects and improve crystallization. (C) 2009 American Vacuum Society. [DOI: 10.1116/1.3253087]