Room-temperature deposited Ti/Au films on Si toward wafer-level MEMS hermetic packaging

Purpose This study aims to present room temperature deposition of an Au film buffered by a thin Ti film on a Si wafer that possesses smaller residual stress and better thickness uniformity, contributing to wafer-level hermetic packaging through Au–Si eutectic bonding. Design/methodology/approach Residual stress and thickness uniformity of room-temperature deposited Au film buffered by a thin Ti film were optimized concurrently by systematically adjusting deposition pressure, sputtering current and the spatial relationship between the target and the wafer. Findings Residual stress down to 18.2 MPa and thickness uniformity down to ±4.3% can be achieved concurrently in a 100 nm thick Au film buffered by a thin 10 nm thick Ti film on a 4-inch Si wafer. Originality/value Therefore, this room-temperature thin film deposition technique is applicable for developing wafer-level microelectromechanical systems hermetic packaging.