A study on annealing mechanisms with different manganese contents in CuMn alloy

In this paper, the effect of Mn in the CuMn alloy was investigated. And an optimized concentration of Mn in CuMn alloy used as barrier layers was also determined. The electrical and material properties of Copper (Cu) (0.1–10 at.% Mn) alloy and pure Cu films deposited on silicon oxide (SiO2)/silicon (Si) are researched. A diffusion barrier layer was self-formed at the interface during annealing, and the growth behavior followed a logarithmic rate law. The microstructures of the Cu–Mn films were analyzed by transmission electron microscopy (TEM), and then correlated with the electrical properties of the Cu–Mn films. After annealing, several Cu alloys and pure Cu films appeared to aggregate and the resistance of the films increased. The Cu atoms diffused into the dielectric layers after annealing at 500 °C under vacuum condition. However, no agglomeration and Cu were found in the SiO2 layer using Cu–Mn alloy with an appropriate amount of Mn, suggesting that a MnSixOy layer is a suitable barrier for Cu. In the experiment, we found that Mn concentration is one of the key factors in the semiconductor process, and the Cu-5 at.% Mn film demonstrates the best barrier properties.

► We optimized concentration of Mn in CuMn alloy used as barrier layers.
► Mn concentration is one of the key factors in the semiconductor process.
► The Cu atoms in the Cu-10 at.% Mn films diffused with the group of Mn atoms.
► The Mn concentration cannot be raised without limit.
► The Cu-5 at.% Mn film demonstrates the best barrier properties.