Effects of deposition conditions on stoichiometry of off-axis RF sputtered BiSrCaCuO thin films

The composition of as-grown BiSrCaCuO superconducting thin films has been investigated as a function of the RF magnetron sputtering variables, i.e. total sputtering pressure, substrate temperature, and oxygen partial pressure in an off-axis configuration. This study shows that use of off-axis geometry alone is insufficient to completely overcome the resputtering problem due to energetic particle bombardment on the substrate. The bismuth loss in the sputtered films at low sputtering pressure and copper loss at high pressure, both of which were aggravated at increasing temperatures, were observed. The mechanisms of thermally enhanced resputtering and gas scattering effects at high pressure are proposed to interpret the discrepancy between target and film composition.<>