Comparison of x-ray diffraction, wafer curvature and Raman spectroscopy to evaluate the stress evolution in Copper TSV´s

In this work we compare techniques to measure the stress in Cu through silicon via´s (TSV´s) and study the stress as a function of post-plating anneal time and temperature. Our results show that each technique was able to measure the stresses with good agreement. However, wafer curvature was limited to measuring the in-plane stress and the top down Raman spectroscopy geometry is dominated by the out-of-plane stress. Only x-ray diffraction could measure all principal stress components, showing high in-plane stress for longer post-plating anneals that could affect transistor performance.