Metalorganic chemical vapor deposition of tungsten nitride for advanced metallization

Abstract

In this study, the physical and electrical properties of tungsten nitride thin films deposited by thermal decomposition of bis(tertbutylimido)bis(tertbutylamido)tungsten have been investigated. The films have an excellent step coverage over high aspect-ratio contact holes as well as a low carbon concentration. Strong W-N double bonds in the precursor preserved the nitrogen atoms during the pyrolysis process. This method subsequently yielded low-resistivity films. A decrease in film resistivity from 4300 to 620 mu Ohm cm corresponded to an increase in the deposition temperature from 500 to 650 degrees C, X-ray diffraction (XRD) and wavelength dispersive spectroscopy (WDS) results indicated that the as-deposited films have face centered cubic (fcc) phase polycrystalline structures with excessive nitrogen atoms. (C) 1996 American Institute of Physics.