The properties of Cu metallization based on CuMgAl alloy buffer layer

The properties of Cu metallization based on CuMgAl alloy thin film as buffer layer were investigated in view of adhesion, diffusion and electronic properties in order to develop the applications of Cu metallization. The perfect adhesion of Cu film was obtained for the deposited CuMgAl buffer layer at 2.5 sccm oxygen flux and 250 °C substrate temperature. The resistivity of Cu film decreases with the increased substrate temperature and has a maximum for 2.5 sccm oxygen flux in the deposition of CuMgAl film. A much-desired taper angle and a little critical dimension bias for the Cu/CuMgAl interconnect line were obtained in one wet etching step. Auger electron spectroscopy (AES) shows that the CuMgAl alloy barrier layer deposited at 2.5 sccm oxygen flux and 250 °C substrate temperature has good anti-diffusion between Cu film and substrate due to the formation of Mg and Al oxides in the interface of CuMgAl /substrate.