考量任意繞線角度之多層重分佈層不規則矽穿孔繞線系統

Abstract

多層重分布層 (redistribution layer) 在先進封裝製程中被廣泛的應用於多晶片間，即訊號在凸塊焊墊 (bump pad)與線路接位置 (I/O pad)間的傳輸。傳統重分布層中的繞線僅允許使用 90 度或者 135 度的轉角來進行繞線。隨著製程的演進，現今的扇出型封裝中(integrated fan-out) 可以使用任意鈍角進行繞線，此製程演進提供更多的繞線可能，通過充分利用任意鈍角的繞線，我們可以得到相對於傳統繞線角度架構下更短的總線長。

在本論文中，我們提出了第一個適用於多層重分布層的任意角度繞線系統。首先，我們給出了一種新穎的，具有精確繞線資源估計的全域繞線模型。接著，我們拓展了文獻中調整連線接點位置的演算法，在多連線系統中快速調整並更新連線接點的位置。最後，我們開發了一種高效的細部繞線系統，在固定接點位置下得到接近最佳解的細部繞線結果。

實驗結果顯示我們的繞線系統相比於目前最先進的單層任意角度繞線器可以得到更高的繞線率，並且，相比於傳統繞線角度的繞線結果，我們的繞線系統在考量非自由配對 (pre-assignment) 與混和式配對(unified-assignment) 的測試連線中，皆可得到不錯的線長優化。

Redistribution layers (RDLs) are widely applied for signal transmissions in advanced packages. Traditional redistribution layer (RDL) routers use only 90- and 135-degree turns for routing. With technological advances, routing in RDLs can be any obtuse angle, leading to larger routing solution spaces and shorter total wirelength.

In this thesis, we propose the first any-angle routing algorithm in the litera ture for multiple RDLs. We first give a novel global routing algorithm with accurate routing resource estimation. A multi-net access point adjustment method is then proposed based on dynamic programming and our partial net separation scheme. Finally, we develop an efficient tile routing algorithm to obtain valid routes with fixed access points.

Compared with the state-of-the-art any-angle router, the proposed algorithm can obtain higher routability in the benchmarks. Besides, the experimental results show that our algorithm can achieve a shorter wirelength compared with traditional RDL routers in the pre-assignment (PA) and unified assignment (UA) benchmark sets, respectively.