Thermal stress of 140 nm-width Cu damascene interconnects

We found two failure modes induced by thermal process at 150/spl deg/C and 350/spl deg/C in 140 nm Cu interconnects. One is two-dimensional (2D) agglomeration in which 140 nm-width line metal is pulled into the wider root metal. The other is three-dimensional (3D) agglomeration in which 130 nm via metal is pulled toward the upper wide metal. 140 nm Cu structural analysis using EXAFS also shows two types of structure change, presumably corresponding to each failure modes.