Dielectric conduction mechanisms of ULK/CU interconnects: Low field conduction mechanism and determination of defect density

The low field conduction mechanism in advanced Cu/ULK interconnects is consistent with 3D phonon-assisted hopping conduction in exponential band-tails. From these measurements, a defectivity parameter proportional to the density of defects near Fermi level is deduced. In addition, the relative fraction of interface versus bulk defect states may be obtained using measurements for several dielectric thicknesses. This parameter may be obtained at nominal operating conditions, it is therefore a good parameter for realistic reliability studies of advanced interconnects.