Analysis of stress in chemical vapor deposition tungsten silicide film

Stress in chemical vapor deposition (CVD) tungsten silicide film was studied by changing the flow ratio of SiH4 and WF6, deposition temperature, and annealing temperature. It was revealed that the stress is tensile on the order of 109 dyn/cm2. Stress is not significantly influenced by the flow rate of SiH4, but it is greatly influenced by the composition ratio of Si and W. As the film becomes Si rich, the stress is reduced remarkably, and after annealing its value peaks at 500 °C. This behavior was analyzed using an x-ray diffractometer and secondary ion mass spectrometry (SIMS). Annealing behavior of the stress can not be explained solely by the Nakjima–Kinoshita model which indicates that increase of tensile stress is caused by grain size increase, but it can be fully explained by adding to the model an expression which takes the grain structure and orientation into account. A tensile stress increase accompanies reaction between the tungsten silicide film and Si substrate at a high temperature of 1100 °C.