A Pencil Probe System for Electrochemical Analysis and Modification in Nanometer Dimensions

A pencil-shaped electrochemical transducer system for analysis or surface modification in nanometer dimensions has been developed. High aspect ratio tip structures are shaped, combining isotropic and anisotropic deep reactive etch processes, forming the body of the transducer. In this way, an aspect ratio of greater than 20 with a tip radius of smaller than 50 nm can be achieved. Subsequently, a three-layer system (an isolation layer: silicon nitride, a metal layer: platinum or gold and an isolation layer: silicon nitride) is deposited on the tip structure. Planarization of this structure in combination with an etch-back process enables precise exposure of the buried metal layer producing an electrode dimension of 100 nm at the tip. Electrochemical and impedance spectroscopic characterization shows electrochemical functionality of the transducer system. Due to the high aspect ratio topography, this probe is particularly well suited for Scanning Electrochemical Microscope (SECM) methodologies. Furthermore, this technology promises a feasible production possibility for both arrays of electrochemical probes and probes on cantilevers