Determination of mechanical properties of copper at the micron scale

Micro-bending and micro-compression experiments that were conducted on single crystal oriented copper (Cu) specimens to determine its mechanical properties are discussed. Both kinds of experiments exhibited a strong size effect on the flow stress with decreasing sample size. The exponents of a power-law fitted to the experimental data were found to be -0.8 for the micro-bending specimen and 0.4 for the micro-compression specimen. Models proposed in the literature dealing with dislocation starvation, dislocation nucleation, and dislocation pile-up were discussed. The damaged surface due to the Ga+ ion bombardment during focused ion beam (FIB) preparation was investigated using Auger electron microscopy. The results of the experiments show that the substantial depth of implantation up to 35 nm and Ga content reaching 20% may cause dislocation pile-ups, which in turn would alter the deformation behavior expected compared the undamaged Cu.