Characteristics of thermal stresses in Al(Cu) fine lines. II. Passivated line structures

The effects of oxide confinement on the thermal stress and yield behavior of passivated Al(Cu) line structures have been studied as a function of linewidth to submicron dimensions using a bending-beam technique. Principal stresses in the passivated line structures were deduced based on a micromechanical analysis of the curvatures of periodic line structures with lines oriented parallel and perpendicular to the beam direction. Results from the passivated Al(Cu) lines show that with decreasing linewidth, the magnitude of the principal stress components become higher until the line aspect ratio approaching one, then decreased. This behavior is consistent with theoretical predictions by analytical methods and finite element analyses. The stress behavior of the oxide passivation has also been deduced and its magnitude depended on the oxide morphology at the sidewall of the lines. Our result indicates a high level of stress in the sidewall which may cause crack formation during thermal cycling. © 1995 American Institute of Physics.