Quantitative capacitance measurements of MOS structures using a scanning probe microscope

This paper describes the simulation and implementation of a method by which an atomic force microscope with scanning capacitance microscopy (SCM) capability can be employed in a nontraditional fashion to quantitatively measure the capacitance of metal-oxide-semiconductor (MOS) structures. The capability to deduce sample capacitances is based on resonant frequency shifting, which relies on the SCM's ultra-precise capacitance sensor. The technique, however, is distinct from scanning capacitance microscopy imaging, with the MOS capacitor an integral part of the system resonant circuit. SPICE simulations are performed to extract phenomenological resonant circuit parameters specific to the instrumentation, subsequently permitting sample capacitance to be quantitatively extracted from the system response. Our technique represents a novel application of SCM instrumentation and has important applications in the analysis of on-chip passive components for future technology generations. Initial experimental results are promising, suggesting the extension of the technique to advanced technology nodes.