Influence of grain size of Cu target on its magnetron sputtering erosion and parameters

Herein, the Cu target is prepared by combining different pieces, with a large variation in grain size, and installed in a UDP-650 closed-field unbalanced ion coating machine for sputtering experiments. The influence of grain size on surface morphology and sputtering performance of Cu targets is studied under the same process conditions. In the constant current mode, the sputtering voltage of target continues to decrease during the target lifetime, which is consistent with the increase of magnetic field intensity on the target surface due to the decrease of target thickness. During the first 7.5 h of sputtering erosion, the sputtering yield of Cu target slightly increases with sputtering time, followed by a gradual decrease. The results reveal that the grain size renders a significant effect on surface morphology of the Cu target after sputtering. The Cu target with small grain size renders high particle density in the edge area of sputter erosion groove, however, the particle-like morphology size is not influenced by the grain size. In the deepest region of sputtering erosion, the Cu target with two distinct grain sizes presents a flat morphology and the smaller grain size results in more flat morphology. At each stage of the life cycle of target material, the Cu target sputtering voltage initially decreases and, then, gradually becomes stable, while the cavity pressure initially increases and gradually becomes stable. The sputtering yield of the samples, with the grain size of 10–20 μm, is found to be greater than the samples with the grain size of 120–150 μm during each stage. Therefore, the Cu target with a small grain size should be selected to ensure the desired film deposition rate and stability of the sputtering process.