Porous Au/Ti Bilayer Thin-Film Getters Based on Black Silicon for MEMS Vacuum Packaging

Porous thin-film getters are extensively utilized in the field of MEMS vacuum packaging. Nevertheless, their effectiveness is frequently constrained by the comparatively modest effective surface area of conventional planar structures. In this work, a porous Au/Ti thin-film getter based on a three-dimensional black silicon scaffold is developed to enhance the effective surface area and improve gettering performance. The fabrication of black silicon nanostructures is achieved through an SF₆/O₂-based inductively coupled plasma (ICP) etching process, followed by the deposition of Au/Ti bilayer films by DC magnetron sputtering. The morphological evolution of the Ti film on the nanostructured substrate and the activation behavior of the Au/Ti bilayer are systematically investigated using scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The results demonstrate that the shadowing effect during sputtering leads to the formation of a porous film with increased surface roughness and an open structure. XPS analysis demonstrates that there is a significant increase in the oxygen content on the surface at higher activation temperatures. This suggests that effective sorption capability is achieved following activation. In comparison with planar substrates, the three-dimensional black silicon scaffold has been demonstrated to promote the formation of a more open and functional structure. The results obtained from this study indicate that the proposed fabrication strategy offers a feasible and MEMS-compatible approach for the construction of porous thin-film getters, thereby enhancing their effective surface area.