Evaluation of Grain Size Distributions of 50nm Wide Cu Interconnects by X-ray Diffraction Method

Grain size distributions of 50nm wide Cu interconnects made by DC electroplating have been evaluated by a rapid and non-destructive method using X-ray diffraction. The influence of the thickness of electroplated excess Cu film and the depth and width in the trench on the grain size distribution in Cu interconnect was examined. The mean grain sizes of annealed 50-130nm wide and 200-30nm deep Cu interconnects were found to be expressed as a linear function of the product of the excess Cu film thickness times the ratio of trench width to trench depth.