A Power Grid Optimization Algorithm by Direct Observation of Manufacturing Cost Reduction

With the recent advances of the VLSI technologies, stabilizing the physical behavior of VLSI chips is becoming a very complicated problem. Power grid optimization is required to minimize the risks of timing error by IR drop, defects by electro migration (EM), and manufacturing cost by the chip size. This problem includes complicated tradeoff relationships. We propose a new approach by observing the direct objectives of manufacturing cost, and timing error risk caused by IR drop and EM. The manufacturing cost is based on yield for LSI chip. The optimization is executed in early phase of the physical design, and the purpose is to find the rough budget of decoupling capacitors that may cause block size increase. Rough budgeting of the power wire width is also determined simultaneously. The experimental result shows that our approach enables selection of a cost sensitive result or a performance sensitive result in early physical design phase.