Room-Temperature Bonding Using Fluorine Containing Plasma Activation and Its Bonding Mechanism

Room-temperature Si/Si wafer direct bonding has been achieved successfully without wet chemistry treatment as well as no requiring annealing. Very strong bonding strength of Si/Si pairs, close to the bulk-fracture strength of silicon, is demonstrated at room temperature thanks to adding small amount of carbon tetrafluoride (CF4) into oxygen plasma treatment. Moreover, we focus on several crucial issues, such as effects of plasma treatment parameters on bonding strength, characterizations of bonding surface and interface. For this fluorine containing plasma activated bonding, fewer water molecules at bonding interface may be prone to produce many covalent bonds via polymerization reaction and result in strong bonding at room temperature