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

Abstract

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.