A reflectometric study of the reaction between Si and WF6 during W-LPCVD on Si and of the renucleation during the H2 reduction of WF6

Article abstract of DOI:10.1149/1.2085676

The formation of W through the reduction of WF₆ by Si is monitored in situ using a wavelength adjustable reflectometer. The reflectance-time relation can be understood and modeled by assuming island growth and a statistical distribution of the island thickness. The model is supported by SEM and Auger observations. The effect of surface layers like native oxides or a plasma treatment on the inhomogeneous Si consumption by the reaction between Si and WF₆ (gouging) and its effect on the reflectance-time relation are understood. The model is also applicable in the case of renucleation during the H₂ reduction of WF₆. A renucleation step consists of the deposition of SiH₄ followed by the Si consumption by WF₆. A renucleation step reduces the surface roughing which occurs during the H₂ reduction process.