We have investigated the relationship between the presence or absence of Co (00.2) layer orientation and the characteristics of Cu filling into trenches. High-vacuum planar magnetron sputtering systems were used in the deposition of Co and Cu. Co-coated substrates with different Co (00.2) layer orientations were used in experiments on Cu filling into trenches of a width of 40 nm and aspect ratio 10. From the results of the Cu filling experiments, Cu filling into trenches was observed in substrates with Co (00.2) layer orientation. Similar Cu filling was also observed in trenches of a width of 20 nm and aspect ratio 4.5. We concentrated on lattice misfit between the Co (00.2) layer and the Cu (1 1 1) layer as the reason why Cu filling occurred in substrates with Co (00.2) layer orientation, and conducted a study from the capillary theory. (C) 2015 Elsevier B.V. All rights reserved.