積體電路生產線上結合缺陷數與群聚指標之Hotelling T2多變量管制圖

Abstract

近年來隨著積體電路（Integrated Circuit, IC）製造業者所生產的晶圓面積不斷增大，其製程越來越複雜，使得晶圓上缺陷(defect)出現群聚(clustering)的現象，因而造成以卜瓦松(Poisson)分配為基礎之傳統缺陷數管制圖（c-chart）不再適用。許多中外文獻雖然針對晶圓上的缺陷群聚問題提出了各種不同的方法來修正缺陷數管制圖，然而這些方法各有不周延之處。因此本研究的主要目的是考慮在缺陷出現群聚現象的情況下，利用缺陷數與無需任何統計假設下的群聚指標(Cluster Index, CI)，發展出一個Hotelling T2多變量管制圖(multivariate quality control chart)構建流程，可以有效地同時監控晶圓表面之缺陷數與缺陷群聚嚴重程度。本研究最後以新竹科學園區某積體電路公司之實例來驗證本研究之有效性及可行性。

For the integrated circuits (IC) manufacturer, the clustering of defects on a wafer due to the complicated manufacturing process becomes more evident with increased wafer size. The defect clustering phenomenon causes the Possion based c-chart invalid. Many modified control charts has been developed to reduce the false alarms caused by defect clustering problem. However, there are still some actions in employing these control charts. This study proposed a statistical process control method for monitoring wafer defect with clustering phenomenon. The method employs Hotelling T2 control chart using the combination of defect counts and cluster index as a modified measurement index for wafer defect with clustering. A case study is also presented, the results indicate that the proposed method is more effective than that of previous studies.