Resonator For Tip-Wear Monitoring On The Atomic Force Microscope

Abstract

This thesis presents a novel RF MEMS resonator composed of an aluminum nitride transducer placed on top of a silicon tip, such as those used for atomic force microscopy (AFM). The objective is to be able to sense tip wear as manifested as small dimensional changes at the tip apex. This thesis demonstrates proof-of-concept: frequency shifts in response to blunting of the tip at 6.39GHz. Furthermore, operation of the resonator up to 20GHz is shown, demonstrating the ability to resolve tip wear on the scale of nanometers. This AFM resonator was designed with the intention of providing inline characterization of tip wear for use in the atomic force microscope, as well as other scanning probe microscopes. Such a real-time monitoring tool would potentially increase throughput of nanoscale measurements, which is invaluable both for the microtechnology industry as well as scientific research. The AFM resonator has potential impact beyond increasing throughput of current metrology tools. One area of nanofabrication research focuses on using functionalized AFM probes to create nanostructres. Exact control over the tip dimensions is crucial for maintaining control over the growth of the nanostructure. Beyond application as a sensor, the AFM resonator can also be used to create a high frequency point source of acoustic energy.