Oxidation on Target Surface in RF Sputtering of Iron Targets

To investigate the sudden change in deposition rate and film structure at a critical value of the oxygen gas partial pressure (Po2) during reactive sputtering of iron targets, the authors formed film at various rf input powers, while measuring the temperature of a thermocouple placed between target and substrate. A hysteresis effect in the temperature with respect to input power was found, which was concluded to correspond to oxidation of the target surface, and corresponding increased emission of secondary electrons. Changes in the hysteresis loop with increasing pressure Po2 supported this hypothesis.