Leveraging Porous Silicon Carbide to Create Simultaneously Low Stiffness and High Frequency AFM Microcantilevers

Abstract

Many operative modes of the atomic force microscope (AFM) are optimized by using cantilever probes that have both a low force constant and a high resonance frequency. Due to fabrication limitations, however, this ideal cannot be achieved without resorting to sizes incompatible with standard AFM instrumentation. This project proposes that cantilevers made from electrochemically etched porous silicon carbide (SiC) enjoy reduced force constants without significantly sacrificing frequency or size. The study includes prototype fabrication, as well as parametric experiments on the etching recipe and suggestions to improve the process. Analysis of the mechanical properties of the prototypes proves that introducing porosity to the structure greatly reduces the force constant (porous k = 0.27 bulk k) while only slightly reducing the resonance frequency (porous f0 = 0.86 bulk f0).