Formation of an Epitaxial CoSi2 Layer with Reduced Oxygen Contamination

Abstract

The formation of epitaxial CoSi2 using an oxide buffer layer is known to be sensitive to the oxygen contamination of the Co film. The oxygen contaminants may originate from various oxygen sources such as ambient annealing. The presence of an oxynitride buffer layer and a Ti-capping layer affect the growth of epitaxial CoSi2, resulting in good epitaxial quality and excellent interface morphology between the Co film and Si substrate. Almost no interference due to oxygen contamination was observed, in spite of intentional exposure of the Co film to air. The oxynitride buffer layer could effectively control the flux of the Co into the Si, resulting in a coherent interface between the CoSi2 and the Si without the formation of additional SiOx. Moreover, the Ti-capping layer could absorb oxygen, resulting in less oxygen contamination. This capping layer positively affected the interface morphology between the Co-silicide and the Si substrate.