A proposal for accurately modeling frequency-dependent on-chip interconnect impedance

Skin effects should be considered for accurate deep-submicron (DSM, 0.35 μm and below) interconnect modeling. Conventionally the sheet-ρ for uniform or plasma-etched conductors is reasonably constant, so the frequency-dependent skin effect can be found by straightforward field simulations, which require sheet-ρ being constant. In that case, the skin-depth is primarily function of harmonic frequency and the environment. However, for damascene-processed conductors, the sheet-ρ is function of line width. Therefore, the impedance (resistance and inductance in this paper) has to be determined by field solvers using a new methodology we propose in this paper. For each DSM technology, sets of interconnect structures with comprehensive range of line widths and neighbors for each metal level are provided and simulated in advance. In this way, a library for each DSM technology is available for accurate and efficient VLSI interconnect modeling