利用虛擬金屬填充提昇晶片中訊號可觀察性

Abstract

這篇論文提出將電路布局完成後留存的虛擬金屬填充與電路中訊號相連，進而使得可觀察訊號數增加，提昇電路中訊號的可觀察性。首先分析了聚焦離子束技術在觀察電路中訊號時所受到的制限，並且舉出了在未修改電路前聚焦離子束所能觀察到訊號數量在各層間的分布以說明可觀察度與訊號所在層數間的關聯性，以及高層虛擬金屬填充接入訊號與低層訊號在電路總可觀察訊號數量上的取代關係。接下來以同一組設定參數對於不同的測試電路進行修改，都得到小幅改進。最後綜合了之前所得到的數據及實作經驗，對未來可能的改進提出了建議。

This thesis proposes a methodology to connecting dummy metal fills with signals in order to increase the observability of signals. At first we present the requirements and restrictions of signal observation by FIB (Focused Ion Beam) technology. The characteristic of the distribution of signals observable by FIB is also discussed after applied observability test on original circuits. By the breakdown charts there shows the relation between signal observability and the highest level the signal could reach. And the substitution effect on observability obviously exists between the new added dummy metal fills and the lower level signals. After all the analysis and discussion, we use a set of parameters to modify each test circuits. The result shows the observability increase marginally in each case. We suggest some possible architecture renovations and the limit of this topic at last.