Characterization of Wafer Level Metal Thermo-Compression Bonding

The process of wafer-level bonding is being successfully used to form MEMS devices. Wafer level bonding may be realized by different methods such as thermo compression, transient liquid phase, anodic, glass frit, or polymer bonding. These methods have different requirements and the choice of wafer level bonding method is defined by the application type. Metal TCB has a wide variety of applications with materials of choice including Au, Cu and Al. 3D electrical connections are created by the use of Cu-Cu TCB; while CMOS MEMS devices may be realized by Al-Al TCB. In this study the wafer level bonding process of Cu-Cu and Al-Al TCB are characterized. The effects and significance of various bonding process parameters and surface treatment methods are reported on the final bond interfaces integrity and strength. Analysis methods include SAM, SEM, AFM, and four point bending test. Al-Al TCB samples were investigated on the interfacial adhesion energy and bond quality. IAE and bond quality were found to be posit...