Floating Random Walk-Based Capacitance Simulation Considering General Floating Metals

Accurate capacitance calculation for structures including floating metals is of great interest to both the modeling of interconnect wires and the verification of on-chip capacitors in the design of integrated circuit. The former problem involves regular-shape or cuboid floating dummy fills, and has been addressed with an existing fast algorithm based on floating random walk (FRW) method. The latter problem involves floating metals in more general and complex shape, and is crucial for the design of high-density metal-insulator-metal (MIM) capacitor which endures higher voltage. How to efficiently handle these general-shape floating metals becomes a challenge. In this paper, we first investigate the mechanism of the existing FRW-based approach for handling floating dummies, and then propose an approach based on the central difference formula for handling the general-shape floating metals. The proposed approach has comparable cost to the existing work, but is much more reliable and accurate. Experiments on the structures with floating dummies and MIM capacitor structures have validated the effectiveness and advantage of the proposed approach.