Scanning Impedance Probe Microscope

Abstract

A new sensitive scanning impedance probe microscope (SIPM) that uses have a wavelength resonator with conjunction with a diplexer connected to a vector network analyzer (VNA), which can perform a very sensitive capacitance measurement at the tip of a conductive atomic force microscope is the subject of this invention. This is achieved through transformation of the high impedance (very small AFM tip capacitance between tip and sample to ground) to 50 Ohm (or any other system's characteristic impedance) through a half a wavelength resonator and diplexer. The VNA measurement architecture as exists today has the capability of measuring impedances close to the characteristic impedance of the analyzer (i.e. 50 Ohms) to a good precision and up to 100 GHz stimulus frequency .The precision and resolution of the DUT (device under test) impedance markedly drops as it deviates from 50 ohms by a couple of order of magnitudes specially in the case of the capacitance between the AFM tip and sample to the ground. We are proposing a solution which remedies the lack of precision and resolution for large and small impedances (small capacitance) when measured by existing VNA.