The use of a WLR technique to characterize voiding in 0.25 and 0.18 μm technologies for integrated circuits

A quantitative correlation has been successfully demonstrated between the isothermal wafer level test results and severity of voiding in sub-micron interconnect lines. Isothermal test T_50% and T _0.1% decrease while sigma increases, as the voiding becomes more severe. The isothermal wafer level test gives a good signal to indicate a significant decrease in severity of voiding with an anneal after metal etch and when a TiN underlayer is present in the metal stack. The isothermal test is thus shown to be a useful reliability tool for process monitoring and void detection in VLSI interconnects