Simultaneous through-silicon via and large cavity formation using deep reactive ion etching and aluminum etch-stop layer

Through-silicon via (TSV) fabrication technology is demanded in the fields like MEMS device fabrication, hybrid MEMS packaging, three-dimensional IC die stacking and system-in-package (SiP) device integration. In some applications, simultaneous etching of TSVs with different aspect ratio is required. Because of the well-known micro- and macroscopic nonuniform etching effects, this is rather challenging. In this work, an optimized TSV fabrication technique based on a deep reactive ion etching (DRIE) and aluminum etch-stop layer that enables simultaneous etching of TSVs with almost arbitrary aspect ratio is presented. The technique is demonstrated by simultaneous formation of 50 mum diameter vias and 5times5 mm² cavities in a 280 mum thick silicon wafer.