Failure behavior of ITO diffusion barrier between electroplating Cu and Si substrate annealed in a low vacuum

A structure of Cu/ITO(10 nm)/Si was first formed and then annealed at various temperatures for 5 min in a rapid thermal annealing furnace under 10⁻² Torr pressure. In Cu/ITO(10 nm)/Si structure, the ITO(10 nm) film was coated on Si substrate by sputtering process and the Cu film was deposited on ITO film by electroplating technique. The various Cu/ITO(10 nm)/Si samples were characterized by a four-point probe, a scanning electron microscope, an X-ray diffractometer, and a transmission electron microscope. The results showed that when the annealing temperature increases near 600 °C the interface between Cu and ITO becomes unstable, and the Cu₃Si particles begin to form; and when the annealing temperature increases to 650 °C, a good many of Cu₃Si particles about 1 μm in size form and the sheet resistance of Cu/ITO(10 nm)/Si structure largely increases.