Evaluation of quasi-hermetic packaging solution for MEMS

A methodology is proposed to estimate the actual influence of important factors during steady-state Temperature Humidity aging tests on SiN passivated MEMSs: temperature-humidity effects, protection by epoxy resins and SiN passivated layer. The developed packages become a hybrid thin-film hermetic encapsulation consisting of an internal shell using PE-CVD SiO, a seal layer coating with resin, and an external protective layer formed by PE-CVD SiN. The process is fully compatible with standard low-cost back-end-of-the-line (BEOL) technologies for LSIs package. This hybrid structure was very effective for protecting the MEMS device from external moisture. In this work, accelerated aging tests on MEMS were carried out, with or without SiN passivated layer.