Fabrication of a microscopic four-point probe and its application to local conductivity measurement

摘要

A microscopic four-point probe for local conductivity measurement is presented. The silicon nitride based atomic force microscope (AFM) probe with a V-shaped two-dimensional sliced structure tip is patterned by using a conventional photolithography method. The probe is then etched to four parallel electrodes isolated from each other, for the purpose of performing current input and electrical potential drop measurement. The newly developed four-point AFM probe not only inherits the function of generating AFM surface topography but also has the capability of characterizing the local conductivity simultaneously. The nano-resolution position control mechanism of AFM allows the probe to scan across micrometer sized areas and create a high spatial resolution map of the in-plane conductivities. Experiments have shown this four-point AFM probe to be mechanically flexible and robust. The repeatable conductivity measurements on the surface of aluminum and indium tin oxide (ITO) thin films indicate the technique, which is based on this four-point AFM probe, has potential application for characterizing devices and materials in microscale.