A low-temperature process that combines high-aspect-ratio polymer
structures with electroless copper plating to create laterally compliant
MEMS structures. These structures can be used as IC-package interconnects
that can lead to reliable, low-cost and high-performance nano wafer-level
packaging. High-aspect-ratio low CTE polyimide structures with low
stress, high toughness and strength were fabricated using plasma etching.
The dry etching process was tuned to yield a wall angle above 80 degrees
leading to an aspect ratio higher than 4. The etching process also leads
to roughened sidewalls for selective electroless plating on the sidewalls
of the polymer structures. These fabricated structures show reduction in
the stresses at the interfaces and superior reliability as IC-package
nano interconnects. Metal-coated polymer structures from MEMS fabrication
techniques can provide low-cost high-performance solutions for
wafer-level-packaging.