Development of a new microscopic four-point AFM probe for the measurement of local electrical conductivity

A microscopic four-point atomic force microscope (AFM) probe with concomitant experimental technique for local conductivity measurement is presented. A silicon nitride based AFM contact-mode probe with a V-shaped tip, which patterned by using the conventional photolithography method, is selected. The probe is then etched to four parallel isolated electrodes for the purpose of performing current input and electrical potential drop measurement. The new probe not only inherits the function of surface topography generating but also has the capability of characterizing the local conductivity simultaneously. The nanoresolution position control mechanism of AFM allows the probe scanning across micrometers sized area and creating high spatial resolution map of the in-plane conductivities. Experiments have shown the microscopic four-point 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 has potential application for characterizing the devices and materials in microscale.