Microstructural characterization of inlaid copper interconnect lines

The microstructure of inlaid Cu lines has been quantified as a function of annealing conditions, post-plating, and post-CMP. The grain size distribution was measured using the median intercept method, crystallographic texture was characterized by pole figure analysis, and mechanical stress was determined using x-ray diffraction. The median grain size and mechanical stress level increase with increasing anneal temperature. The crystallographic texture is independent of the anneal temperature and is predominantly(111) with a small fraction of sidewall-nucleated (111) grains. The (111) grains nucleated from the trench bottom have a preferred in-plane orientation. The grain growth in the trench is independent of that in the overburden.