| 초록 |
For thin films the tensile residual stress can lead to cracks in thin films whereas compressive residual stress may cause films delamination from substrate. These phenomena inevitably contribute to the reduction of reliability of thin films. The intrinsic stress behavior of thin films was observed during deposition using the measurement of substrate curvature. When the deposition of thin films was interrupted, the stress was relaxed to a certain level depending on the time. Understanding the phenomenon of the stress relaxation may help to produce thin films with excellent reliability with controlled residual stress in thin films. In this paper, the stress relaxation behavior in thin films was observed in terms of deposition rate and substrate temperature. The amount of the stress relaxation was increased with increasing the deposition rate for Cu thin films deposited at room temperature up to the thickness of 100nm. Higher deposition rate may cause more number of atoms to flow into grain boundary during thin film growth. When the film growing process was interrupted, entered more atoms into grain boundaries for higher deposition rate might flow back to the grain surface due to the chemical potential difference, in turn resulted in more the stress relaxation. For Cu thin films the amount of stress relaxation was affected by the state of stress; at compressive stress range more relaxation was observed, while less or nominal stress relaxation was observed at tensile stress regime. |
