Interfacial Investigation And Mechanical Properties Of Multiple-stack Andoic Bonding Process

BF33 glass is widely used for MEMS devices fabrication and packaging because of its excellent properties,such as heat-resist,optical performance,chemical resistance and mechanical properties.It can be bonded with semiconductor and metal materials.Anodic bonding is one of the most versatile bonding processes to permanently bond glass-to-metal at relatively low temperatures.The Si-glass-Si,Al-glass-Al and Al-glass-Si were successfully bonded together by the two-step anodic bonding process,and the glass and Ni were soldered at low temperature under atmosphere.The effects of bonding process parameters on the interfacial structure and mechanical properties were discussed.The major results are shown as follows:?1?The Si-glass-Si was successfully bonded together by the two-step anodic bonding process.Na+ would precipitate from the back of the glass,and a Na+ depletion region formed at the bonding interface.There are two different regions in the depletion region: low-field region and high-field region.In the high-field region,all anions and alkaline ions are transferred by the high electrical field.In the relatively low-field region,the electrical force is too weak to transfer anions,resulting in the formation of a thin anions layer.In the second bonding process current character different from that in the first bonding process,there are two peak currents during the second bonding process.?2?The Al-glass-Al/Si was successfully bonded together by the two-step anodic bonding process.It was shown that ion migration play an important role during the bonding process.O2-diffused into the bonding interface and reacted with the Al3+,which resulted in the successful process.It was also found the Al3+ migrated into the glass,which may enhance the bonding process.For all investigated temperatures and voltages,the strength of Al-glass-Al joints was higher than for the Al-glass-Si joints.?3?For the first time,the Al foil was used as the transitional layer to bond glass and Ni.The typical interfacial structure are glass/Al/Al₈ZnSn₄+solder/Ni₃Sn₂/Ni.The Ni-glass bonding interface is observed to withstand the tensile test,as the glass substrate is broken,but not the bonding interface.