SHAPE CHANGES OF VOIDS IN BAMBOO LINES: A NEW ELECTROMIGRATION FAILURE MECHANISM

摘要

The behaviour of electromigration-induced voids in narrow, unpassivated aluminium interconnects is examined. Failure voids are categorized in two different types: extended wedge-shaped voids and narrow slit-like voids. The occurrence of slits is found to increase with decreasing current density and line width. It is observed that shape changes of voids lead to the formation of the slit-like voids. These shape changes may consume a major part of the lifetime of a conductor line. A model to describe the evolution of the void shape is presented.