Integrated circuit with standard cell logic and spare gates

Abstract

Abstract An integrated circuit comprises an array of standard cell logic having spare gate logic dispersed therein. The spare gate logic is connectable to the standard cell logic through upper level conductors. This allows the design of an integrated circuit to be changed by changing the pattern of the upper level conductors, thereby lowering the cost of making a design change and reducing the disturbance of the original wiring. In an illustrative embodiment, the top two or three metal levels and associated vias are mask-programmable for this purpose. The interconnections from the mask-programmable upper levels to the underlying standard cell logic is accomplished using a regular array of conductor vias interspersed throughout the standard cell array, plus elevated output terminal which create a loop structure completed by the program levels. This allows output terminal loops of the standard cells to be brought up to the mask-programmable metal levels for removal of any standard cell logic. The spare gate logic comprises a relatively small percentage of logic gates as compared to the standard cell logic (typically less than 20 percent). This allows for the economies of production usually associated with conventional standard-cell ASIC arrays, while providing for economical and rapid repair of logic errors and/or the implementation of changes in logic functionality, by requiring changes in only the top metal levels.

Inventors

• 👤 John Anthony Schadt

Bibliographic Details