500+ MHz designs using deep-submicron (DSM) copper interconnects require accurate and efficient modeling of cladding-metals' frequency-dependent impedance [1]. In this paper, for the first time, we simulate and describe the current distribution inside a copper-based interconnect in a rich set of multi-line structures. The difference of the resistivities of copper alloy and the cladding metals causes a non-monotonic current density versus cross-wire axis relation. The same situation does not

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... r for the state-of-the-art aluminum processes. It enlarges the inductance by more than 12 percent. Simulating the frequency dependence of the inductance with this property, we find that PEEC [2][3] can simulate cladded wire profile to achieve accurate inductance extraction. Other approximate methods result in inaccurate and lower inductance values. A new modeling methodology based on library look-up is then proposed to make an efficient field-solver based extraction flow for realistic DSM designs. KEYWORDS Copper interconnect, skin-effect current distribution, cladding material, electromagnetic field solvers.