Nanometer-scale characterization of SiO2/Si with a scanning capacitance microscope

A novel scanning capacitance microscope (SCaM) is developed using a tungsten stylus as a cantilever. The deflection of the cantilever is detected by projecting the cantilever onto a photodetector. A combined SCaM, atomic force microscope (AFM), and scanning tunneling microscope has been constructed. The spatial resolution for SCaM measurements is estimated to be less than 100 nm. Local electrical properties of a SiO2/Si system are investigated using the SCaM and AFM functions of the combined microscope. A lateral p-n junction is formed, by ion implantation of P into a lightly B-doped Si wafer, the structure is then annealed and thermally oxidized. It is demonstrated that (1) the p-n junction can be observed even through the oxide layer, (2) the local impurity concentration can be estimated from capacitance-voltage (C-V) characteristics, and (3) P diffuses into the B-doped region during the thermal processes. (C) 1996 American Institute of Physics.