Time Evolution of Stress and Microstructure in Electroplated Copper Films

The time evolution of galvanically plated copper films designed for semi additive processing (SAP) was investigated. Blanket copper films were plated at three current densities. Stress was monitored with the substrate curvature method during and after film growth. Lattice strain and crystallite size were monitored with X-ray diffraction. At room temperature, all the films recrystallized after a few hours of plating. During recrystallization, stress in the deposit increased and the microstructure coarsened. Differential scanning calorimetry (DSC) measurements were performed to predict isothermal recrystallization. Calculated recrystallization profiles based on the DSC data are compared with the actual processes observed by the evolution of the stress and strain.