Materials Science and Engineering A 459 (2007) 262–272 FIB damage of Cu and possible consequences for miniaturized mechanical tests D. Kiener a,b,∗ , C. Motz b , M. Rester b , M. Jenko c , G. Dehm b,d a Materials Center Leoben, Forschungs GmbH, A-8700 Leoben, Austria b Erich Schmid Institute of Materials Science, Austrian Academy of Sciences, A-8700 Leoben, Austria c Institute of Metals and Technology, SI-1000 Ljubljana, Slovenia d Department of Material Physics, Montanuniversit¨ at Leoben, A-8700 Leoben, Austria Received 13 September 2006; received in revised form 22 December 2006; accepted 7 January 2007 Abstract Cu specimens were exposed to Ga + ion bombardment for varying conditions of ion energy, ion dose, and incident angle in a focussed ion beam workstation. Conventional transmission electron microscopy investigations were employed to analyze the Ga + ion induced damage. The extent of visible damage was minimized by reducing the ion energy and furthermore by using grazing incident ions. Concentration depth profiles of the implanted Ga were measured by Auger electron spectroscopy. Concentrations of up to 20at.% Ga were found several nanometers below the surface. Ga contents of more than 2 at.% were detected within a depth of up to ∼50 nm. Mechanical consequences in terms of possible hardening mechanisms are discussed, taking into account the experimental findings along with Monte Carlo simulations. A non-negligible influence of the ion damage is predicted for submicron-sized samples. © 2007 Elsevier B.V. All rights reserved. Keywords: Focussed ion beam (FIB); Ion damage; Auger electron spectroscopy (AES); Transmission electron microscopy (TEM); Mechanical properties 1. Introduction From the 1980s onwards the focussed ion beam (FIB) micro- scope has been mainly used in the semiconductor industry as a tool for device imaging, modification and mask repair. Sev- eral years ago, the FIB technique has found a broader variety of applications in material science [1]. This increased use is due to several key factors: (i) site-specific preparation of thin foils for transmission electron microscopy (TEM) investigations, (ii) a strong channelling contrast allowing discrimination of different grain orientations, and (iii) secondary ion mass spectroscopy (SIMS) and/or energy dispersive X-ray (EDX) spectroscopy attached to the FIB workstation for local chemical analyses. Recently, the FIB became popular as a tool for machining minia- turized samples [2–7] to investigate the influence of sample dimensions on mechanical properties. As the surface to volume ratio is large for submicron-sized test structures, any surface ∗ Corresponding author at: Materials Center Leoben, Forschungs GmbH, A- 8700 Leoben, Austria. Tel.: +43 3842 804 112; fax: +43 3842 804 116. E-mail address: dkiener@unileoben.ac.at (D. Kiener). modifications by ion bombardment and implantation may criti- cally alter the mechanical properties. So far, detailed studies on FIB induced Ga + ion damage were mainly performed on semiconductor materials, especially Si [8–15]. TEM investigations revealed the width of the amor- phous surface layer introduced by ion milling to be in the order of several tens of nanometers, depending mainly on the kinetic energy and incidence angle of the used ions, and on the milling geometry [8–13]. Comparison of these results to Monte Carlo simulations, mainly using the SRIM code [11,13–15], showed good agreement. Few data on other materials is available [16–19], and the applied methods and parameters differ remarkably, preventing a conclusive comparison. Therefore, we decided to investigate the Ga + ion damage of Cu, a material we frequently investi- gate with respect to mechanical size effects [5,7]. In addition to TEM investigations of the Ga damaged microstructure, Auger electron spectroscopy (AES) measurements were carried out for reliable information on the depth profile of the Ga concentra- tion. The results are compared to SRIM calculations. Finally, the impact on mechanical data obtained by FIB-made mechanical test structures is discussed. 0921-5093/$ – see front matter © 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.msea.2007.01.046