Solid-state reaction-mediated low-temperature bonding of GaAs and InP wafers to Si substrates

Abstract
We report a low-temperature wafer bonding method for the realization of integration of GaAs- and InP-based optoelectronic devices with Si microelectronic devices. This method uses a Au-Ge eutectic alloy as the bonding material sandwiched between GaAs and Si wafers, and between InP and Si wafers. The bonding process was carried out at 280–300 °C by taking advantage of the low-temperature solid-state reactions occurring at GaAs/Au-Ge, InP/Au-Ge, and Si/Au-Ge interfaces. Both the simple mechanical test and standard thermal cycling test prove excellent structural integrity of the joined wafers. Structural analyses reveal only limited interfacial reactions as well as solid-phase epitaxial regrowth of GeSi alloys on the Si substrate.