Surface Modification of Cu Films by Gas Cluster IoN Beams Using Organic Acid Vapor for Wafer Bonding

In this study, surface modifications with gas cluster ion beams (GCIBs) in organic acid environment were investigated for surface activated bonding. We have reported that GCIBs induce low-damage surface smoothing and surface reactions enhancements. In this study, organic acid vapor such as acetic acid is introduced during GCIB irradiation in order to assist surface oxide removal on Cu films. From XPS and AFM measurements, smooth Cu surface without oxide by Ar-GCIB irradiation with acetic acid were confirmed. Cu bonding experiment using this technique shows lower temperature bonding of Cu compared to Ar-GCIB irradiation without acetic acid vapor.