The effects of processing parameters in the chemical vapor deposition of cobalt from cobalt tricarbonyl nitrosyl

This paper reports the development of a thermal chemical vapor deposition process for pure cobalt from the source precursor cobalt tricarbonyl nitrosyl for incorporation in integrated circuit silicide applications. Studies were carried out to examine the underlying mechanisms that control Co nucleation and growth kinetics, including the effects of key process parameters on film purity, texture, morphology, and electrical properties. For this purpose, systematic variations were implemented for substrate temperature, precursor flow, hydrogen reactant flow, and deposition time (thickness). Resulting films were analyzed by Rutherford backscattering spectrometry, X-ray photoelectron spectroscopy. X-ray diffraction, four-point resistivity probe, scanning electron microscopy, and atomic force microscopy. These investigations identified an optimized process window for the growth of pure Co with resistivity of 9 plus/minus 2 mu Omega cm, smooth surface morphology, and root-mean-square surface roughness at or below 10% of film thickness.