A Low Temperature, Non-Aggressive Wafer Level Hermetic Package With UV Cured SU8 Bond

In this paper, we present a new technique that could realize wafer level 3-D hermetic package in a very low bonding temperature (120°C) for MEMS (Micro-electro-mechanical Systems) devices. Microcavities were etched on a host glass wafer and were bonded with a carrier silicon wafer. MicroChem SU-8 photoresist is used as the intermediate adhesive layer between the host and carrier wafer. The devices were fabricated by self-aligning etching technique and were finally sealed by coating the structures with sputtered aluminum. Helium leak testing is carried out to verify the hermetic characteristics of the package, 99.7% of the tested devices were qualified. This technology shows a significant improvement of the hermeticity properties of adhesive bonded cavities, making it particularly suitable for applications on gas-tightness with low temperature, non-aggressive demands.