Thermal stresses in aluminum lines bounded to substrates

Thermal stresses in unpassivated and passivated aluminum thin-film lines bonded to substrates have been calculated using finite-element techniques. For the unpassivated lines, only elastic behavior was considered. The stresses were found to increase with increasing linewidth and with increasing substrate rigidity. Edge effects were found to become nonnegligible for narrow lines. For passivated lines, allowed to deform either elastically or in elastic perfectly plastic manner, the stresses increase with decreasing linewidth, with increasing passivation thickness, and with increasing passivation stiffness. Stresses in elastic perfectly plastic lines are slightly lower and have flatter profiles than stresses in purely elastic lines.>