Ti-Al Film Used as Diffusion Barrier for Copper Interconnection Deposited by RF Magnetron Sputtering

An amorphous Ti-Al film,on which Cu film was in situ prepared,was deposited on the Si (100) substrate by radio frequency (RF) magnetron sputtering to fabricate Cu(100 nm)/Ti-Al (40 nm)/Si samples.The samples were annealed in the temperature range from 400 ℃ to 800 ℃ in high vacuum and then characterized by atom force microscopy (AFM),X-ray diffraction (XRD),and four-point probe methods.The results show that,when the annealing temperature was below 750 ℃,the sample surface was smooth,and the surface root mean square roughness (Rms) and sheet resistance were smaller and did not change with the annealing temperature,and the amorphous Ti-Al film could prevent the interdiffusion between Cu and Si.However,for the sample annealed at 800 ℃,the surace root mean square roughness and sheet resistance increased dramatically,and Ti-Al film could not be used as an effective barrier anymore.