LOGIC CELL PLACEMENT METHOD IN COMPUTER-AIDED-CUSTOMIZATION OF UNIVERSAL ARRAYS AND RESULTING INTEGRATED CIRCUIT

An improved automatic placement process for placing logic cells in a universal array. Unused basic units are assigned to rows to reduce the congestion of the wiring in high congestion regions of a universal array. These assigned unused basic units are allocated among rows in a pyramidal manner. Those unused basic units allocated to a given row are distributed along that row in a manner to reduce wiring congestion. During a pair exchange portion of the placement process, quality criteria used for deciding whether to exchange two logic cells on different rows include skipped rows in a node, y-span of a node, minimizing the number of logic cells in excess of two in a node on a row, making a longest row shorter and making longer a shortest row or one which is within a tolerance of being a shortest row.