Interfacial Characteristics of Copper/Diffusion Barrier/Low Dielectric Constant Material Systems at Elevated Temperatures

抄録

Thermal reactions of sputtered Cu films on the fluorinated silicon oxide (FSG) and organosilicate glass (OSG) layers, with and without TiN or TaN diffusion barrier, were investigated. The sheet resistance, surface morphology, phase formation and compositional depth profile of the mutilayer structures after vacuum annealing at 400 to 800°C were examined. It is found that the sheet resistance values of all samples decreased after annealing at 400 to 600°C and increased after annealing at 700 or 800°C. Without the barrier layer, the increase of sheet resistance was accompanied with the dewetting of Cu films and the carbon outdiffusion for Cu/OSG sample or the Cu indifftision of the Cu/FSG sample. When a TiN/Ti or a TaN/Ta barrier layer was interposed between Cu and the dielectric layer, the degree of dewetting of Cu film was significantly reduced for both systems. The reaction characteristics of the two dielectric systems unon vacuum annealing with and without the barrier laverare discussed.