Tether system designed for flip-chip bonded MEMS

Flip-chip bonding is important to integrate MEMS devices with other components or to make novel devices. The use of tethers when flip-chip bonding is valuable because it enables the release of the MEMS based device prior to bonding. Releasing the device prior to bonding allows the possibility to bond to a substrate that includes materials that are incompatible with the release process, increase yield since any devices lost during release are not bonded, and avoid damage to the bond. This paper presents a set of design rules for devices created with the MUMPs process that can be implemented to allow the device to be tether flip-chip bonded. The rules outline the design of tethers, mechanical stops, and locking bumps, which work as a system to keep the device from slipping or twisting during bonding, but break free from the donor substrate after bonding. Examples of success, reasons for past failures and the solutions are presented.