A wafer-level corrosion susceptibility test for multilayered metallization

Abstract

A wafer-level test for chlorine-induced corrosion is presented for VLSI multilayered metallization. The intrinsic corrosion rate for an arbitrary metallization can be determined by monitoring the electrical resistance rise when the test structure is stored in a fixed corrosive environment. The corrosion activity (rate constant) is found to be directly proportional to the amount of chlorine present on the slice and therefore can be used as an effective in-line process monitor for chlorine-based Al-alloy dry etches. The temperature dependence of the corrosion rate is described by an Arrhenius relationship with an activation energy of 0.3-0.4 eV. The corrosion activity is observed to be time-dependent, i.e. very low initially but rising rapidly to a maximum value, from which it decays slowly with time.<>