A methodology for concurrent process-circuit optimization

In order to optimize integrated circuit designs, it is critical not only for circuit designers to adjust circuit geometries but also for process developers to adjust device characteristics for optimal overall system performance. This paper describes concurrent process-circuit optimization (CPCO), a methodology for concurrent integrated circuit optimization that spans the fabrication process design and circuit design disciplines. CPCO enables process developers and circuit designers to work coordinately toward the common goal of optimizing a system-level objective, and therefore produces better designs than single-discipline optimization schemes. The methodology logically partitions the overall integrated circuit optimization task into loosely coupled process and circuit design tasks that may proceed concurrently-this produces substantial time savings over a flat "all-at-once" optimization approach. Finally, the CPCO method formulates a multiobjective optimization problem that may be used to negotiate tradeoffs in adjusting a single process to optimize multiple circuits, to optimize nominal circuit performances or to improve circuit yield. The implementation of the CPCO method in an extensible object-oriented software architecture is described. Results of applying the methodology to integrated circuit design examples with industrial grade simulation tools are presented. The results demonstrate substantial performance gains over separate process/circuit optimization and substantial time savings over "all-at-once" combined optimization.