Stability of interfacial oxide layers during silicon wafer bonding

The stability of thin interfacial oxide layers between bonded silicon wafers is investigated experimentally and theoretically. For usual bonding temperatures around 1100 °C and typical times of a few hours, the oxygen diffusivity is not high enough to allow the oxide layer dissolution. For aligned wafers of the same orientation, the oxide layer instead tends to disintegrate in order to minimize the SiO2/Si interface energy. It is possible to stabilize a uniform interfacial oxide layer by rotationally misorienting the two wafers by an angle θ exceeding a critical angle, θ crit, estimated to be between 1° and 5°.