Atomic scale observation of corner-voiding effects in advanced interconnects

Abstract

Stress-induced voiding is a major reliability issue in advanced interconnects, and this detrimental phenomenon can be obtained at the corners of Cu lines even in the absence of twin or grain boundaries. An atomic scale description of this phenomenon is proposed. The high tensile strain gradient favors the motion of Cu atoms along the (111) planes. Hence the corners are progressively unfilled to minimize this strain gradient. This issue must be solved in view of further downscaling developments.