2003 Volume 67 Issue 7 Pages 342-347
Resistivities, internal stresses and thermal stability of strongly (111) oriented Cu thin films, which are the most promising interconnect materials in advanced ULSI devices, have been studied comparing with those of non-oriented Cu films. Their internal stresses within a film plain were measured by a conventional X-ray diffraction technique, while the strain distribution with depth by a grazing incidence X-ray scattering (GIXS) methods. The resistivity and X-ray diffraction measurements revealed that present strongly (111) oriented Cu films showed high thermal stability, compared with non-oriented Cu films. The internal stresses of non-oriented Cu films start to saturate above 200°C, whereas those of strongly oriented films tend to decrease at high temperatures. Both internal stress and hardness for the strongly (111) oriented Cu films increase with decrease of film thickness. It was found that the residual internal stresses of highly oriented Cu films increased almost linearly throughout the thickness up to the oxidized Si substrate. The change of the stress distribution with depth was measured as a function of annealing temperatures for strongly oriented Cu films. It was revealed that the change of internal stresses with depth was nearly the same as that of plain stresses with temperature.
