In situ evolution of stress gradients in Cu films induced by capping layers

Depth-dependent stress distributions within copper films possessing capping layers were measured during in situ thermal anneals. Glancing-incidence x-ray diffraction measurements of SiCx Ny Hz capped Cu films revealed that a strain gradient near the cap/Cu interface, created by constraint imposed by the cap during its deposition process, decreased as the sample temperature increased to 350 °C. Although the increase in sample temperature allowed Cu to approach its equilibrium lattice spacing at the cap deposition temperature and minimize the corresponding stress gradient, both the gradient and concomitant increase in residual bulk stress of the Cu film reappeared after cooling to room temperature. © 2010 American Institute of Physics.