A New Method to Fabricate Metal Tips for Scanning Probe Microscopy

We present a new method to fabricate sharp metal tips on cantilevers for a SPM. The metal tip, which is deposited and patterned as a film on a silicon mold with pyramidal etch pits, is attached by metal-to-metal bonding to a metal pad on a substrate. Then the tip on the substrate is peeled off the mold at room temperature. The tip surface is very smooth without grain boundaries associated with deposited thin films. A platinum tip with a radius curvature of less than 15nm was successfully fabricated. In addition, the mold can be reused because the mold is not dissolved during the tip fabrication. By applying this method in which the tip fabrication process is independent of the cantilever process, we succeeded to form a tip on a piezoresistive cantilevers. Moreover, we used the cantilever with the tip in a piezoresistive AFM and an AFM/STM apparatus and obtained high resolution topography and surface conductance images, respectively.