Low-temperature silicon wafer bonding based on Ti∕Si solid-state amorphization

Strong and nearly void-free bonding has been achieved using a low-temperature Ti∕Si-based wafer bonding technique. Bare Si wafers are bonded with oxidized Si wafers at temperatures from 300to450°C, using ∼30nm thick Ti as bonding intermediate. High-resolution transmission electron microscopy and electron energy-loss spectrometry elemental mapping indicate that the strong bonding is attributed to a solid-state amorphization between Ti and Si. Ti demonstrates particularly attractive capabilities to overcome kinetic barriers commonly associated with low-temperature silicon wafer bonding.