Comprehensive study on wafer-level vacuum packaging using anodically-bondable LTCC wafer and thin film getter

An anodically-bondable low-temperature cofired ceramic (LTCC) wafer is a new wafer-level packaging material for micro electro mechanical systems (MEMS). It provides 3-dimensional metal interconnection inside, and enables hermetic sealing, which was guaranteed by automobile-grade thermal cycling tests. In this study, the sealing pressure was first investigated under various anodic bonding conditions with and without two types of thin film getter (PaGe getter, Saes Getters or Ti getter). The vacuum sealing pressure was a few kPa or even higher, and more importantly, often different for each sample without the thin film getter. On the other hand, samples with the getter always exhibited good vacuum level, which was below the detection limit (80 Pa) of zero-balance method using a Si diaphragm. Typical process conditions for borosilicate glass on commercially-available bonding tools work well.