Micro-spring force characterization and applications in integrated circuit packaging and scanning probe MEMS metrology

Micro-springs are characterized and demonstrated in integrated circuit (IC) packaging and microelectromechanical system (MEMS) metrology applications. The springs are based on lithographically defined stress-engineered films and are compliant, electrically conducting and have micrometer scale dimensions. The force-displacement is experimentally measured and found to have constant stiffness through the majority of compression. Fretting experiments are performed to investigate the potential for intermittent electrical contact when the springs are used as a solder-less pressure contact for integrated circuit packaging. While operating at <1 mN of force, orders of magnitude lower than macroscopic connectors, no glitches slower than 4 nsec are observed for thousands of shake cycles. The springs are also demonstrated as scanning probes for non-destructive imaging of high-aspect ratio MEMS structures. Sidewall line-scans and tapping mode images in deep silicon trenches are presented using tip heights over ten times taller than commercial probes.