Advancement in Hermetic Packaging for MEMS: An Al–Si–Ge Ternary Eutectic Bonding Approach With Interring Groove Structure

The enhancement of hermetic packaging is of pivotal significance for the advancement of inertial sensor devices, including MEMS gyroscopes. The aluminum-germanium (Al-Ge) based eutectic bonding technology, renowned for its superior sealing and mechanical strength, has the capacity to significantly enhance the reliability and efficiency of these devices. This study introduces a hermetic packaging technology based on an aluminum-silicon-germanium (Al-Si-Ge) ternary eutectic bonding system that employs a dual-seal-ring and inter-ring groove (IRG) structure. A series of studies were conducted on the morphology of the sealing rings, the helium leakage rates of the packaging units, and the shear strength. These were then compared with the traditional Al-Ge binary system bonding. The results indicate that, under the same bonding parameters, the cross-sections of sealing rings in the Al-Si-Ge ternary system exhibit unique eutectic phases, and the packaging performance in terms of helium leak hermeticity and shear strength surpasses that of the traditional binary system. The performance of the system is found to exceed the limits of MIL-STD-883 by a significant margin, with a leak rate of 3.42×10-9 atm cc/s and a shear strength of 52.62 kg. Furthermore, the IRG packaging structure proposed in this paper has been shown to enhance the sealing and mechanical strength of the packaging cavity. The research findings emphasise the positive impact of the Al-Si-Ge ternary eutectic bonding process and the innovative packaging structure design on the hermetic performance of MEMS devices, offering a new technological approach to improving the performance and lifespan of MEMS.