Oxidation behavior of cobalt silicide and cobalt germanide thin films

We report the results of ultraviolet and X-ray photoelectron spectroscopic (UPS and XPS) investigation of the in situ oxidation of thin cobalt silicide and cobalt germanide layers. This sort of study is the first study in the case of cobalt germanide. Oxidation leads to the formation of overlayers of SiO2 and GeO on cobalt silicide and cobalt germanide respectively. Spectral changes indicate that oxygen approach to the silicide and germanide surfaces induces breakage of the CoSi and CoGe bonds. The metal atoms generated through the dissociation process further bond with Si or Ge atoms underneath. This process explains the retention of silicide and germanide layers even after the formation of over layers of the respective oxides. The oxidation process enables in situ fabrication of insulator/metal/semiconductor structures.