以備用標準單元實現工程變更

Abstract

Engineering Change Order (ECO)指的是在標準設計流程外對原始設計中元件或規格做修正，為目前晶片設計產業面臨的重要議題。隨著晶片設計日益複雜，晶片設計過程不時有修正設計的需求。同時，晶片設計產業的激烈競爭使得time-to-market的壓力更勝以往。為了節省時間，晶片設計者必需以手動的方式修正錯誤或是規格的變更。然而，手動的修改效率低落而且修正的品質不佳。另一方面，光罩的成本也隨著製程增加，就成本的考量，metal-only ECO固定了base layer，設計者只能修正metal layer，可以大幅地降低修改光罩的成本。 本篇論文就post-silicon階段的 metal-only ECO建立了一個自動化合成的系統。給定一個包含實體資訊的設計以及需要執行ECO的清單，這個系統會根據實體設計中所包含的spare cells所提供的cell types逐一替換ECO list，同時最小化替換過程中所增加的連線複雜度。本篇論文的特點在於這個系統融合了既有的合成系統並且考慮了實體資訊，有效的自動化ECO的需求。

ECO is the process of inserting a logic change directly into the netlist to fix functionality or timing violation. It is prevalent for saving either time or cost. Before the manufacture of masks, ECOs save time by avoiding re-building from scratch. On the other hand, metal-only ECO can save time and reduce the cost after the photomaks have been made. It implements incremental design changes using spare cells sprinkled at placement stage. Metal-only ECO realizes the last-minute design changes by revising the photomasks of metal layer only, the photomasks of base layer can be reuse in the next tape-out. ECO is desirable; however, there are rare automatic tools and engineers have to implement ECO manually. In this thesis, we propose an ECO resynthesis methodology, named Guided ABC, that correctly implements the incremental design changes using the available spare cells as well as tries to reduce the prohibitive photomask cost at the same time. The experiments are conducted on five industrial testcases. Guided ABC uses less wirelength and/or fewer cells to complete design changes for all cases than the blind method that synthesizes the ECOs with available spare cell types directly.