Computer implemented method for leveling interconnect wiring density in

Abstract

A digital computer includes a processor, a memory and a program which operate in combination for inputting a placement of cells for an integrated circuit chip, and a netlist of wiring nets interconnecting the cells. The placement is divided into a plurality of contiguous regions, and cell densities in the regions are computed in accordance with locations of the cells in the placement. Wiring densities in the regions are computed in accordance with the locations of the cells and the netlist. The shapes of the regions are altered to produce altered regions such that cell densities and wiring densities in the altered regions are more level or uniform. The placement is then altered such that the cells occupy locations in the altered regions which are relative to their locations in the original regions. The porosities of the cells can also be computed and used in the computation of the region shapes. The wiring densities are computed by constructing bounding boxes around the wiring nets, and computing horizontal and vertical total heights and widths of bounding boxes that overlap the regions. The altered shapes are generated by computing optimal sizes for the regions for containing the cells and required interconnect wiring, computing new lengths for edges of the regions, and iteratively recomputing new positions for corners of the regions using a mechanical mass-spring model until the system reaches equilibrium.