對三維度積體電路實體設計流程具可整合性和具網格分析適應性的溫度模擬器

Abstract

經由提高晶片之間互連導線密度達到成本效益的三維度積體電路，被視為一個解決二維度 平面積體電路的良好替代方案。三維度積體電路確實提供快速成長的電路系統許多益處，然而， 由於主動電路層垂直堆疊造成較高的功率密度和較低的導熱特性，散熱問題成為其所面臨到的 棘手挑戰之一。因此，相較於過往對於溫度只做封裝前的電路驗證是不夠的，對於未來高整合 系統而言，溫度議題的處理需要被提早到實體設計階段做考量。基於這些原因，吾人使用提出 的3D-AADI 演算法於從平面規劃 (floor-plan) 階段到驗證 (verification) 階段，研發了一個具有 網格分析適應性的溫度模擬器。 本篇論文提出的三維度積體電路溫度模擬器，不僅在效率和精準度之間取得平衡的低複雜 度演算法，更可以建造出具適應性分析網格以避免因非關鍵區域造成的不必要時間浪費。此分 析器包含四個程序分別是：熱趨勢的估計、初始適應性網格的建立、非規則性矩陣的建立、和 3D-AADI非規則性矩陣的運算。由實驗結果顯示，此分析器在0.01%的收斂率下達到數百倍的速 度提升，而因線性複雜度，隨著分析解析度越密加速更為顯著。此外，此分析器具有可以部分 更新 (incremental) 的特性對應用於考慮溫度設計流程 (temperature-aware design flow) 中，是十 分有效率的應用。

3D ICs, which deal with cost-effective achievement by increasing the densities of interconnection between dies, are regarded as an attractive alternative solution for overcoming the bottlenecks on 2D planar ICs. 3D ICs offer the increased system a large number of advantages; however, one of critical challenges is heat dissipation due to higher accumulated power density and lower thermal conductivity of inter-layer dielectrics for vertical stacking layers of active tier. In this way, the management of thermal issues should be considered during physical design stages rather than only pre-packaging verification on the future highly integrated systems. For these reasons, we develop an adaptive thermal simulator applying our 3D-AADI algorithm for providing temperature distribution to 3DIC physical design flow from floor-plan level to verification level. The proposed 3DIC thermal simulator, 3D-AADI, both utilizes low-complexity algorithm for achieving both efficient runtime and accuracy and constructs adaptive simulating granularity for avoiding unwanted runtime and resource consumption in non-critical position. Furthermore, 3D-AADI, including estimating heat trend, constructing initial adaptive grids, establishing non-uniform structure, and calculating 3D-AADI matrix processes, improves two orders of magnitude under 0.01% convergence in experimental results. As a result of linear complexity, the finer simulating granularity leads to the more speeding up. Due to the partial updating characteristics, 3D-AADI can not only be regarded as a reliable thermal simulator but also be applied to 3DIC design flow as a thermal-driven kernel.