COMSOL Simulation Study of the Effect of Probe Tip Shape on the Measurement of an Electrical Field Gradient Generated by Microel

Precision, nano-scale electric field measurements are one useful technique for characterizing nanoelectronic devices, and other nanoscaled structures and materials.  The Scanning Kelvin Force Microscopy (SKFM) is one scanning probe technique utilized to measure the surface potential of a biased structure or materials with variations in work function. However, high spatial resolution measurements of electric fields that vary with location are dependent on the shape of the detecting probe tip. COMSOL Multi-Physics models were created for electrical field measurements with representative probe tip shapes and microelectronic test structures.  Data demonstrated that the differential of the potential generated by small changes in tip-sample separation was more sensitive to tip shape than the potential at any given tip-sample separation. Significant decrease of change in potential across the boundary of the ground plane and biased metal line caused by averaging effect of cantilever. The width of the response could also be related to the top width of the conical probe. These results indicate that information about the electrical shape of the tip can be extracted from the measured response using a known field distribution and will be used to help design an electrical tip shape profiler reference material.