SiO2/Si system studied by scanning capacitance microscopy

The applicability of scanning capacitance microscopy (SCaM) in the characterization of SiO2/Si systems was demonstrated. Our SCaM, which is combined with a contact AFM, measures the capacitance derivative against the bias voltage applied to the sample (dC/dV). Line-shaped grooves etched into a SiO2 layer were imaged by SCaM based on the differences in the SiO2 thickness. AFM images were simultaneously obtained. The acquired SCaM and AFM images showed good agreement. SCaM images of the sample were obtained at different dc bias voltages. The contrasts of the SCaM images varied with the de bias. The bias dependence of the image contrasts was compared with the dC/dV-V differences between the thick SiO2 regions and the thin SiO2 regions and with calculated results. The results of this comparison showed good agreement.