Scanning microscopy of higher harmonic capacitance response for Si device

We have devised a novel mode for delineating p-n junction in 2 dimensions using a scanning capacitance microscopy (SCM). We modulate by an ac voltage V the capacitance C of a tiny metal-oxide-semiconductor (MOS) junction comprised by a sharp metal probe tip, a thin SiO/sub 2/ layer and a sample semiconductor, and then detect 2nd harmonic response of C, namely, d/sup 2/C/dV/sup 2/. The 2nd harmonic response shows its characteristic peak at the p-n junction because of the built-in depletion layer.