Cross-sectional investigation by dual bias modulation electrostatic force microscopy on Si/Si junction fabricated by surface-activated bonding

A cross section of an n-type Si/Si junction or a p-type one fabricated by surface-activated bonding was investigated by scanning probe microscopy like atomic force microscopy (AFM), Kelvin probe force microscopy (KFM), and dual bias modulation electrostatic force microscopy (DEFM). From the AFM and KFM observation, a position of the bonding interface was identified. By DEFM measurements, on the other hand, surface depletion capacitance and its dependence on an external DC bias voltage and on a modulation frequency of external AC voltages were examined to discuss carrier transport along the bonding interface. Especially from a comparison of DEFM signals on as-fabricated and thermally annealed samples, a thermal annealing effect on interfacial property has been confirmed.