Study on diffusion barrier layer of gradient Cu doped Be thin films

Abstract

Beryllium was coated onto the polished Cu mandrel with a diameter of 2 mm by direct current (DC) magnetron sputtering. Cu/Be composite capsules were annealed in the range of 250 °C-550 °C, and their mutual diffusion at the low and medium temperature were measured. In addition, different diffusion barrier materials, such as BeO, Be2C and graphite-like-carbon (GLC) films, have been selected and studied for the diffusion barrier effect of Cu. Under the annealing condition of 425 °C, 26 h and nitrogen atmosphere, the diffusion and migration of Cu atoms were investigated. It is found that both BeO and GLC films can effectively halt the diffusion of Cu atoms, but the thickness of BeO barrier layer is thinner than that of GLC films. After annealing, the stress of Be2C thin film increases due to the change of density, and a large area of Be2C thin film is broken and falls off. Its barrier effect becomes very poor, so it is not suitable to be used as a diffusion barrier layer in gradient Cu doped Be thin films.