Comparison of propagation characteristics between single and coupled MIS interconnect topologies in VLSI circuits

The propagation characteristics of single and coupled VLSI interconnects in the metal-insulator-semiconductor configuration are compared. Only the odd-mode of the coupled interconnects is considered by assuming balanced source and load with differential mode signal propagation A hybrid RLCG model is constructed for two coupled interconnects. For very close wires over a typical semiconductor layer of 300 μm, the hybrid RLCG model can be reduced to a simple RLC model with fewer elements. This simple RLC model is compared to other available models. It works well with a small wire spacing between the two interconnects, but it fails when the wire spacing is large. The validity of a simplified model, either a simple two-wire model or a one-wire model, depends on the ratio of the wire spacing s_m to the line width w_m. At low values of s_m/w_m, good predictions can be obtained from the simple RLC model. At high values of s_m/w_m the lines can be treated as two uncoupled RLCG interconnects. Over a broad range of intermediate of s_m/w_mvalues, both models have acceptable accuracy and could be used in practice.