Batch transfer of microstructures using flip-chip solder bump bonding

Wafer-to-wafer bonding for microstructure formation

“…• solder (using thin-film deposited solders or preforms) [1], [62]; • polymer [63]; • low melting temperature glasses (including glass frits) [1], [4]; • thermocompression (using soft metal thin films) [35], [64], [65]. The eutectic bond was explored extensively by Ko and coworkers for the packaging of pressure sensors.…”

“…Some drift mechanisms were identified in pressure sensors that were attributed to this bond [1]. Solder bonding has been employed successfully for several different applications, including recently a novel scheme for microshell encapsulation [62]. Polymer bonds have been used extensively as temporary bonding agents, as in [63].…”

Surface micromachining for microelectromechanical systems

“…Electrical interconnect to underlying electronics is achieved using a copper seed layer to a second aluminum metal contact (not shown). Broken polysilicon tether plates are visible at edges [158].…”

“…An approach to microassembly based strongly on IC technologies is to bring flip-chip-like methods into use for MEMS devices [158]. Initial results indicate that this assembly technique could be appropriate for batch transfer of polysilicon surface-micromachined components as well as molded polysilicon HexSil structures.…”

Flip Chip Technologies and Their Applications in MEMS Packaging

“…As a result, the complexities of these MEMS devices are very limited. Researchers developed flip chip assembly and silicon removal technique [6], This technique is easily applicable with most standard foundry processes and has been successfully used in the packaging of some RF MEMS devices. The entire structure is then thermosonically flip-chip bonded to a target substrate.…”