We have investigated the stress behaviors and a mechanism of void formation in TiSix films during annealing. TiSix thin films were prepared by DC magnetron sputtering using a TiSi2.1 target in the substrate temperature range of 200-500 degreesC. The as-deposited TiSix films at low substrate temperature (<300 degreesC) have an amorphous structure with low stress of similar to1 x 10(8) dynes/ cm(2). When the substrate temperature increases to 500 degreesC, the as-deposited TiSix film has a mixture of C49 and C54 TiSi2 phase with stress of similar to 8 x 10(9) dynes/cm(2). No void was observed in the as-deposited TiSix film. Amorphous TiSix film transforms to C54 TiSi2 phase with a random orientation of (311) and (040) after annealing at 750 degreesC. The C49 and C54 TiSi2 mixture phase transforms to (040) preferred C54 TiSi2 phase after annealing over 650 degreesC. By increasing substrate temperature, the transformation temperature for C54 TiSi2 can be reduced, resulting in relieved stress of TiSi2 film. The easy nucleation of the C54 phase was attributed to an avoidance of amorphous TiSix phase. We found that amorphous TiSix --> C54 TiSi2 transformation caused higher tensile stress of 2 x 10(10) dynes/cm(2), resulting in more voids in the films, than C49 --> C54 transformation. It was observed that void formation was increased with thermal treatment. The high tensile stress caused by volume decreases in the silicide must be relieved to retard voids and cracks during C54 TiSi2 formation. (C) 2003 Elsevier B.V. All rights reserved.