Dependence of Residual Chlorine Amount on Al Grain Size

Abstract

From the investigation of the thermal desorption spectroscopy (TDS) results, it was found that the amount of residual chlorine on Al films increased with increasing Al grain boundary length after 60°C etching and rinsing. The aluminum surface morphology, which was observed by atomic force microscopy (AFM) after etching, indicated that the Al surface was etched along grain boundaries. Consequently, residual chiorine was trapped at the ditches of grain boundaries which were engraved by etching. In the case of -10°C etching, residual chlorine was hardly trapped at the ditches of grain boundaries because engraving along grain boundaries by etching was suppressed at low temperature.