Dresden 2011 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 44: Poster Session I

HL 44.94: Poster

Tuesday, March 15, 2011, 18:00–21:00, P3

Soft landing Indium ion beams produced by a variable energy focused ion beam system — •Yu-Ying Hu, Dirk Reuter, and Andreas D. Wieck — Lehrstuhl für Angewandte Festkörperphysik, Ruhr-Universität Bochum, D-44780 Bochum, Germany

A focused ion beam (FIB) system under conventional operation employs 30 keV ions for micro-fabrication. In this work, the landing energy of ions can be tuned by applying positive voltages on the substrate, i.e. employing a retarding mode: the substrate potential decelerates the 30 keV ions, generating ions with various landing energies given by the difference between the accelerating and the decelerating voltage. The decelerating voltage to be operated on the GaAs substrate is at maximum 30 kV, i.e. soft landing is possible. In this study, we employ ion beams with very low landing energies of a few tens to few hundreds of eV which yields implantation depths in the range of only a few nm according to simulations. An Indium liquid metal ion source is produced for this experiment. The ion-induced damage is reduced due to low landing energy, which is observed through secondary electron images after ion sputtering. Above 29.76 kV decelerating voltage, no ion sputtering trace can be seen on the substrate. The adaptive objective lens voltage has to be reduced to focus the soft landing ion beam. Nevertheless, the diameter of the low energy beam is several µm, i.e., roughly 30 times larger as without a retarding voltage.