Characterization analysis of aluminum pad discoloration and ions contamination monitor of wafer storage environment

In this paper, an aluminum pad discoloration was observed for the wafers stored for more than one year after the CP testing process. The OM, SEM, EDS, AES and TEM analysis technique were used to identify the mechanism of Al pad discoloration. The Pt thin film deposition on top surface of Al pad can effectively enhance the visibility of discoloration. Based on HRTEM, FFT and NBD analysis results, this Al pad discoloration was characterized by the formation of fluorine containing crystalline defects on entire Al pad surface. Additionally, in order to monitor contaminants in Front Opening Shipping Box (FOSB), the ion chromatography analysis technique was introduced into routine wafer storage management of CP testing FAB.