Stress gradients induced in Cu films by capping layers

The presence of capping layers deposited on copper films can create strain gradients through the Cu film thickness. Grazing-incidence and conventional x-ray diffraction measurements determined the in-plane stress of the Cu films as a function of depth. Cu films possessing a SiCxNyH z capping layer exhibited greater tensile stress near the cap than in the bulk, whereas Cu films possessing a CoWP film did not show a gradient. The constraint imposed by the SiCxNyHz cap during the cooling process from the cap deposition temperature (350 °C) leads to an increase in the in-plane stress of 180 MPa from the bulk value. © 2008 American Institute of Physics.