Interfacial adhesive strength measurement in a multilayered two-level metal device structure

摘要

Abstract: Decohesion of thin films in a multilevel metal IC device is an important reliability concern in semiconductor fabrication. In this study we report measurement of film stress and adhesive bond strength between films used to fabricate a two-level metal VLSI device. The device structure was simulated on Si wafers by sequential deposition of blanket films of LPCVD glass, aluminum, bilayer plasma TEOS interlevel dielectric, and aluminum. Film stress was calculated from wafer bow measurements and adhesive strength was measured using a micro-peel test. Our measurements for all the interfaces showed strong interfacial bonding, greater than the fracture strength of silicon. We also identified that the interface between two layers of plasma TEOS interlevel dielectric can be affected by processing conditions. To insure the robustness of the device structure, the adhesive strength of this interface was studied as a function of various processing parameters. Both individual and cumulative stresses for the device films were measured. The calculated intrinsic peel forces show that spontaneous adhesion failure at the device interfaces is unlikely for optimized processing conditions. !10