Wafer-Level Package With Simultaneous TSV Connection and Cavity Hermetic Sealing by Solder Bonding for MEMS Device

In this paper, a wafer-level package with simultaneous through silicon via (TSV) connection and cavity hermetic sealing by low-temperature solder bonding for microelectromechanical system (MEMS) device such as resonator is presented. Wet etching technique combined with dry etching technique is utilized to achieve a ldquoY-shapedrdquo through wafer interconnection structure to shorten the TSV in order to reduce cost. Ansoft HFSSTM3-D electromagnetic simulator is used to assess the transition properties of signal with frequency of the new interconnection structure. Sn solder bonding is utilized to achieve simultaneous TSV connection and cavity hermetic sealing. Average shear strength of 19.5 Mpa and excellent leak rate of around 1.9 times 10-9atm cc/s have been achieved, which meet the requirements of MIL-STD-883E. Kevin structure is also fabricated to measure the resistance of the metallized TSV, the resistance of the ldquoY-shapedrdquo through wafer interconnection and the contact resistance of the Cu/Sn IMC bond joint.