RF-MEMS wafer-level packaging using through-wafer via technology

This paper presents wafer-level packaging (WLP) solution for RF-MEMS applications based on through-wafer via (TWV) technology in high-resistivity silicon (HRS). A pre-processed HRS capping wafer containing recesses and vertical Cu-plated TWV interconnect is, after alignment, bonded to the RF-MEMS wafer providing environmental protection and easy signal access. Optionally, cavities can be formed simultaneously with TWV in the capping wafer, which allows hybrid co-integration of additional IC dies while maintaining overall thickness of the resulting SMT compatible package. This cavity can also be used for a first-level wafer-to-wafer alignment accuracy check. After bonding, the s-parameter measurement at giga hertz level shows little influence introduced by the capping substrate.