Si Nano-tip Sharpening and Fabrication of Narrow-gapped Dual AFM Probe

Abstract

This paper reports on fabrication and characterization of sharp Si nano dual AFM (atomic force microscope) tip. The narrow-gapped dual AFM tip was formed by self-align etching technique based on Si trench reactive ion etching, trench refilling with spin on glass (SOG), SOG etching and polishing back, and Si crystalline anisotropic etching to form triangular pyramid with inclined Si (111) plane and two vertical planes. When corner angle of the Si trench pattern was changed from 90° to acute angles, needle end of the dual tip was geometrically sharpened. In addition, radius of curvature of the dual tip was sharpened by low-temperature thermal oxidation even though gap between the tips slightly widened about 290nm. Moreover, Si dual tip fabrication was demonstrated on a dual AFM cantilever with sputtered FePd film on Silicon on insulator (SOI) wafer.