Studies of the Twin Coherency on Electroless (111) Nanotwins

Recently, additives-induced highly (111)-textured nanotwins in electroless deposition have revealed significant potential for applications in the electronics industry. This study aims to investigate the mechanical and electrical properties of the electroless deposited highly (111)-textured copper (Cu) that can be heavily influenced by the lattice arrangement within these nanotwins, specifically through twin coherency. Coherency in nanotwinned Cu is often determined by a specific lattice arrangement called Coincidence Site Lattice (CSL) grain boundaries. The degree of this alignment is represented by the <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\Sigma$</tex> value, with a lower <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\Sigma$</tex> value indicating a higher degree of coincidence, generally corresponding to lower energy and a more stable structure. In this study, two (111) textured electroless deposited nanotwinned Cu films with varying proportions of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\Sigma 3$</tex> {111} coherent twin boundaries were fabricated. Various tests, including cross-sectional observation, electron backscatter diffraction analysis, nanoindentation, and electrical resistivity, were conducted to assess the impact of twin coherency on this engineering material.