In-plane fabricated insulated gold-tip probe for electrochemical and molecular experiments

In this contribution we present a scanning probe with a gold-tip completely encapsulated with insulator all the way to the apex. The probe fabrication is unique owing to an in-plane arrangement in which the width of the cantilever is defined by deep reactive ion etching (DRIE). E-beam lithography was employed for defining the gold nanowire tip. The cantilever and the chip body were defined by DRIE in later steps. The radius of curvature of the tip apex is around 20 nm. The high-quality insulation on the tip was demonstrated by performing electrodeposition of gold. The spring constant of the cantilever was obtained by measuring the resonance frequency of the cantilever. With this in-plane fabrication process, probes with different spring constants ranging from 0.1 N/m to 9 N/m were fabricated on the same wafer.