Copper as the future interconnection material

Cu film was evaluated as a candidate for future interconnection. As the device dimensions are scaled below 0.5 μm, the RC time constant of interconnection becomes a major part of the total delay. By reducing the resistivity of interconnect, the operating speed can be increased by more than 20% without any change in design rule. An electroless deposition process is proposed to solve the Cu patterning difficulty. Patterns of 2.0-μm pitch were achieved with this process. Copper contamination was addressed, and dielectric films such as silicon oxynitride and silicon nitride were shown to be effective in stopping Cu diffusion. The authors also investigated Cu corrosion. By coating a thin Ni film on Cu they reduced the corrosion from 0.2 μm/h to less than 0.05 μm/h at 100°C in 1-mol/1 KCl solution