Electroplated and Dry-Released Metallic Microstructures for a Lateral Tunneling Unit Application

This paper presents a new method of fabricating a lateral tunneling unit (LTU), by dry releasing of electroplated structures. An LTU is an integrated tunneling current sensing unit that has a tunneling tip and a linear actuator for moving the tip. The new fabrication method has many advantages over the existing polycrystalline silicon structure and hydrofluoric acid (HF) wet release method, namely, use of a metallic material, thicker structure, higher yield, and a safer, easier, and faster process. New LTUs and LTU-AFM probes were successfully fabricated by this method. Gold and nickel were used as alternative structural materials. The electrolytic polishing method was proposed as a new post-release processing and was used to fabricate sharp needles. The comb-drive actuator of an LTU was operated and the characteristics were measured; the results showed that this actuator has good linearity.