以Ti-W有圖晶圓進行無塵室環境中HCl微污染分析研究

Abstract

隨著半導體元件之線寬縮小至奈米級，晶圓尺寸也進展到了以12吋為主力，使得製程環境污染的防治重點已由微粒轉移至氣態分子污染物上。氣態分子污染物中又以氯(Cl)離子沉積在晶圓上所造成的金屬線腐蝕報廢最為常見。業界目前偵測氣態分子污染物之主要方法有兩種：以直讀儀器為主的及時性偵測方法，以及以採樣加上後續分析的非即時性監測方法。兩種方法各有其優缺點，但無非都是要達到及早偵測環境氣態分子污染物之異常濃度，以儘早採取必要措施，提高生產良率為目的。 本研究於某廠區無塵室中，分別使用直讀式IMS偵測儀以及Impinger+IC非即時性監測方法來同步監測無塵室空氣中的氯離子濃度，以比較兩種監測方法之差異。再以直讀式IMS偵測儀長期量測結果建立無塵室內之氯化氫氣體濃度分佈。此外也運用有圖晶圓作為偵測金屬線腐蝕的方法，分別在微環境控制系統下以及實廠內以有圖晶圓進行觀測，以了解產生金屬線腐蝕之濃度下限。 研究結果顯示直讀式IMS偵測儀以及Impinger+IC非即時性監測兩者之數據呈正相關，無塵室內氯化氫氣體濃度分佈則顯示較高濃度的區域為乾蝕刻區; 微環境控制系統實驗發現腐蝕之濃度下限為2~4ppb，而實廠發現金屬線腐蝕時之平均濃度則為1.5ppb。

As the line width of semiconductor components has been shrunk into nano-scales and wafers have been progressed to the 12-inch size, the target compounds of micro-contamination control have been changed from micro-particles to the gaseous molecular pollutants of AMC (Airborne Molecular Contamination). In the AMC pollutants, the most possible species which lead to serious impact are chloride ions (Cl-). It may cause corrosion of the metal line, and scrap the wafer in huge amount. Currently, the semiconductor field detects the clean room inorganic AMC pollutants by two ways: direct-reading instrument of IMS monitoring or non-direct-reading of impinger + Ion Chromotography (IC) method which separates sampling and analysis of the AMC. In this study, both IMS and impinger + IC monitoring are used to monitor the Cl- concentration of clean room air, and the monitoring results of the two methods are compared. The Cl- concentration distribution in the clean room is established by IMS. In addition, this study uses pattern wafers to evaluate metal wire corrosion effect under controlled micro-environment as well as under real fab clean room. The results showed that monitoring data by IMS are positively correlated to those by impinger + IC method. The distribution of chloride ion concentration in the clean room environment indicated that dry etching area has relatively higher concentrations. It was also found that the critical Cl- concentration leading to the metal wire corrosion is 2 ~ 4ppb in controlled micro-environmental tests. But in a real fab clean room environment the critical one-hour averaged Cl- concentration in the ambient air is 1.5ppb.