Study of chemical vapor deposition reaction between tungsten hexafluoride and silicon difluoride

Abstract

A low-pressure chemical vapor system which deposits tungsten based thin films on a substrate, using a horizontal hot-wall reactor has been studied. WF ₆ and SiF ₂ were used as precursors to deposit materials containing tungsten, at temperatures between 100 and 800 °C. Results demonstrate that a deposition temperature below 400 °C led to polycrystalline tungsten and silicon oxide. Tungsten films deposited at higher temperature (300–400 °C) were normally present in the α structure while for those tungsten films deposited at lower temperature (<300 °C), XRD patterns indicated mixed α and β phases. As the reaction temperature was increased to ≥500 °C, polycrystalline tungsten silicide and polycrystalline silicon were deposited on the surface of the substrate. This study investigates the effect of different processing conditions for forming W and WSi ₂ and the role of SiF ₂ in their formation.