Thin-layer Au-Sn solder bonding process for wafer-level packaging, electrical interconnections and MEMS applications

Abstract

The developed bonding process utilizes AuSn solder and provides liquid-proof sealing and multiple reliable electrical connections between the bonded wafers. The bond can withstand 300°C and features a thin bond line (2–3 µm), high bond strength, excellent bond gap control, and low stress due to small amount of bonding material. A Nb/Au seed layer was shown to be an optimal adhesion and barrier film.