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Electrochemical Nanolithography

by Rosso Michel - published on , updated on

Participants : P. Allongue and F. Maroun

Post-docs : O. De Abril (2009) and A. Gündel (2005)

Electrochemical nanolithography is a technique allowing etching of a conductive substrate in one step and without application of a mask. The method, derived from “electrochemical machining”, was developed in collaboration with R. Schuster (now at KIT, Karlsruhe). We use an electrochemical AFM with a metalized tip and apply ultra short voltage pulses (∼ 20 ns) between the tip and the substrate

The in situ AFM image in Fig. 1a shows nine cavities generated by localized dissolution in a Cu thin layer on Au. A comprehensive investigation of the system parameters (pulse height and duration, number of pulses, solution resistivity) was conducted and quantitatively accounted for with the equivalent electrical scheme shown in Fig. 1b. As an example, Fig. 1c displays the influence of solution concentration on the cavity diameter. Figure 1d explains that the localization of the reaction arises from a spatio-temporal variation of the electrochemical double layer charging The method was applied to create Co/Au(111) stripes and investigate the propagation of magnetic domains (collaboration, LPS, Orsay).

Figure 1 : (a) In situ AFM image showing 9 cavities obtained by localized dissolution of a Cu thin film under the tip. Voltage pulses are 20 ns long. (b) Equivalent electrical scheme used to model the process; (c) Influence of the solution resistivity : comparison experiment (data point) – model (solid line); (d) Spatio-temporal variations of the potential at different distances from the tip – surface point of contact.

Publications :
 O. de Abril, A. Gundel, F. Maroun, P. Allongue, and R. Schuster, "Single-step electrochemical nanolithography of metal thin films by localized etching with an AFM tip," Nanotechnology 19 (32) (2008)
 P. Allongue, P. Jiang, V. Kirchner, A. L. Trimmer et R. Schuster, "Electrochemical Micromachining of p-Type Silicon", J. Phys. Chem. B, 108 (2004) 14434-14439
 R. Schuster, V. Kirchner, P. Allongue and G. Ertl, "Electrochemical Micromachining, Science, 289 (2000) 98-101