濺鍍碳化鈦擴散阻礙薄膜在銅製程之應用

In this study, Tac diffusion barriers were grown on Si wafers by using a Tac target in a sputtering system. The effects of Tac thin films on the high temperature diffusion behaviors between copper and silicon were examined by resistance measurement, x-ray diffraction (XRD), scanning electron microscope (SEM), and transmission electron microscope (TEM). It shows that the as-deposited TaC is a NaCl structure, with a resistivity of 251 µΩ·cm. The results of the relative changes in sheet resistance (ΔR/R0 for Si/Ta(10nm)/ Cu(100nm) stacked samples as a function of annealing temperature shows that ΔR/R0 increases slowly at a low annealing temperature and then increases drastically at a specified heightened temperature. It increases slightly at temperatures below 600°C, and rises abruptly when the temperature exceeds 650°C. The sheet resistance results consist with the examinations of XRD and SEM. The ultra-thin 10 nm TaC appears to be an effective diffusion barrier material for Si/TaC/Cu metallization up to at least 550°C. Moreover, TEM observations clarify that the failure mechanism is that local defects of Tac barrier films are induced by high temperature annealing, consequentially, Cu atoms diffuse through the local defects of TaC, then copper suicides are formed.