XPS and TEM studies of oxidation states on Sn solder ball

Abstract

A Sn oxide layer on the surface of Sn solder balls plays an important role in the semiconductor packaging industry. This paper shows a comprehensive analysis of the Sn oxide layer by XPS depth profiles. The distribution of Sn with different oxidation states can be derived from curves fitting Sn3d5/2 peaks. Moreover, the oxide layer thicknesses obtained from XPS demonstrate a linear correlation with the values from TEM measurements.