Stress in thin TaSixfilms sputtered on polycrystalline silicon was studied as a function of temperature. A dual laserhyphen;beam apparatus was used to measure wafer curvatureinsitu. Stress was studied in the TaSi2/undoped polysilicon structure, in TaSi2on polysilicon doped with either phosphorus, arsenic, or boron, and in films with a deposited Si/Ta ratio of more than 2. Several observations of stresshyphen;temperature behavior in TaSi2were made. Tensile stress in TaSi2/undoped polysilicon increases to 1.2times;1010dyn/cm2at 450thinsp;deg;C during the postdeposition anneal, decreases to near 0 at 900thinsp;deg;C, and linearly increases as temperature is subsequently lowered. Both doping and stoichiometry affected the stresshyphen;temperature behavior.Nhyphen;type dopants decreased tensile stress and boron did not. Raising the Si/Ta ratio increased tensile stress at high temperatures. The stresshyphen;temperature measurements were combined with results from other characterization techniques to draw conclusions about the influence of temperature on the film. TaSi2compound formation was found to occur at less than 400thinsp;deg;C in these films.
展开▼
