Eutectic bonding on large silicon die using deposited gold-tin multilayer composites

Conventional bonding techniques using gold-tin preform or paste often require a process temperature over 320/spl deg/C to ensure complete melting of the preform. However preform or paste usually leads to difficult alignment and sometimes contamination due to the flow state in reflow soldering. In this paper, we report a gold-tin eutectic bonding process which uses deposited multilayer composites. The bonding medium consists of a Au-Sn multilayer deposited directly on the wafer to be bonded. This technology eliminates the requirement of preforms, inhibits tin oxidation and provides good control of bonding layer thickness. Results of bonding of 5 mm/spl times/6 mm silicon die show that high quality bonding has been achieved.