Low-resistivity PdCoO₂ thin films with rigid interlayer bonds for advanced interconnects

We report the sputter deposition and characterization of low-resistivity layered oxide PdCoO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>. Metallic delafossites PdCoO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> and PtCoO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> are among the highest-conductivity anisotropic metals. In this study, we grew c-axis oriented PdCoO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> thin films on sapphire substrates using DC and RF reactive magnetron sputtering. The PdCoO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> thin films exhibited a resistivity in the range of 4–5 μΩcm. Besides, Mohs hardness testing indicates that the PdCoO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> thin films have a hardness between 6 and 8 on the Mohs scale, which is comparable with SiO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>. These results demonstrate the high-conductivity and mechanical robustness of PdCoO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>, indicating the potential as an advanced interconnect material.