Planar MEMS RF capacitor integration

Abstract

MEMS capacitor switches have been integrated with high voltage CMOS ICs. The MEMS were formed with the final three AlCu wiring levels in SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> using a planar sacrificial silicon cavity process. The MEMS cavities were hermetically sealed at less than atmospheric pressure at wafer level. After Pb-free solder bumping, the MEMS chips are packaged in organic laminate packages. The capacitor portion of the MEMS beam has a capacitance density of ~0.12fF/μm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> and the pull-in, restoring, self-actuation, and break down voltages are on the order of 25V, 10V, >;45V, and >;150V respectively. MEMS cycling lifetime over 250 Mcycles with no fails has been demonstrated. This paper summarizes the critical integration, yield, and reliability issues associated with developing this rf MEMS technology.