Ge/SiO2 low temperature wafer bonding

Atomic level Ge/SiO₂ direct wafer bonding was achieved at 150°C. The microstructures of the bonding interface were characterized by transmission electron microscopy. Our investigation indicated that the completed Ge/SiO₂ bonding interface without nano-gaps can be required only if the proper pretreatment was applied. That is probable reason that the high defect (a great number of pits) density on the surface of the transferred Ge layer in GeOI was caused through these buried interface nano-gaps which were invisible by an infrared inspect due to the limited resolution.