Surface amorphization, sputter rate, and intrinsic stresses of silicon during low energy Ga+ focused-ion beam milling

NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS

卷:267

Article; Proceedings Paper

Pastewka, Lars^1,2  Salzer, Roland³  Graff, Andreas³  Altmann, Frank³  Moseler, Michael^1,2,4 

[1] Univ Freiburg, Inst Phys, D-79104 Freiburg, Germany

[2] Fraunhofer Inst Werkstoffmech IWM, D-79108 Freiburg, Germany

[3] Fraunhofer Inst Werkstoffmech IWM, D-06120 Halle, Germany

[4] Freiburger Mat Forschungszentrum, D-79104 Freiburg, Germany

关键词: Surface amorphization;    Focused ion beam milling;    Molecular dynamics;    Silicon;   

DOI  :  10.1016/j.nimb.2009.06.094

来源: Elsevier

【 摘 要 】

Transmission electron microscopy (TEM) is a standard technique to characterize microelectronic device structures. As structures shrink to the nanoscale, surface damage produced by focused ion beam (FIB) sample preparation destroying the region of interest and degrading the resolution of TEM images becomes increasingly a problem. The thickness of the damaged layer at the sidewalls of a prepared cross section is around 20-30 nm for silicon at typical beam energies of 30 keV. In order to reduce these artifacts to a minimum low beam energies have been proposed for FIB polishing. We use a combination of molecular dynamics simulations and experiments to assess the influence of the focused ion beam on the surface structure of silicon for beam energies ranging from 1-5 keV and a grazing angle of 100 typically used in low voltage FIB polishing. Under these conditions, the thickness of the amorphous layer depends linearly on the beam energy. Intrinsic surface stresses introduced by FIB are always tensile and of a magnitude of around 1 GPa. (C) 2009 Elsevier B.V. All rights reserved.

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