半導體廠金屬蝕刻機台於預防保養時之空氣污染物逸散控制研究

Abstract

半導體金屬蝕刻製程主要使用氯氣及氯化硼等氣體，以高能電漿離子化產生自由基後使其與晶圓表面之鋁反應將多餘之鋁蝕刻而產生溝槽。為維持晶圓生產良率須定期進行腔體的預防維護保養，主要清除反應腔壁所附著製程副產物，在此過程中在打開密閉反應腔及擦拭腔壁時會產生極刺鼻味道且含有毒性氣體，會逸散至潔淨室，造成勞工健康危害並汙染製程。本研究之主要目的在於利用數值模擬方法研究應用材料公司P5000金屬蝕刻機台於預防保養時的空氣污染物逸散控制方法與控制效率。前人曾以1000 ppm的追蹤氣體SF6在腔底連續釋放，測試反應腔上方有氣罩或反應腔上方無氣罩時的在側邊大量抽氣(3130 L/min)的控制效率，本研究則利用數值模擬方法驗證實驗數據，並探討側邊抽氣流率改變時對空氣污染物逸散的控制效率。 研究結果顯示，不論反應腔上方全開(無氣罩)或上方有氣罩時在反應腔上方進行大量抽氣，可有效地控制危害性氣體的逸散，模擬的控制效率結果與實驗數據相符合，且發現在人員呼吸帶的SF6濃度均低於FTIR之偵測下限。當側邊抽氣流率降低但仍維持在一定流量以上時，空氣污染物的逸散仍可有效的獲得控制，而反應腔上方有氣罩時的控制效率會優於無氣罩時的控制效率。

Main process gases used in the metal etcher of the semiconductor industry are chlorine and boron chloride. Process gases are ionized in the reactor chamber to form free radicals by plasma, which etches off aluminum film from the wafer surface. To increase the product yield, by-products deposited on the chamber wall must be cleaned periodically during preventive maintenance. As the chamber is being cleaned, toxic gases are released which may disperse in the clean room posing heath threat to workers, contaminate process tool, and create wafer defects. The main objective of this study is to use the numerical model to investigate the control method of pollutant dispersion and its control efficiency for a type P5000 metal etcher of Applied Materials Inc. during preventive maintenance. In previous work, sulfur hexafluoride (SF6) tracer gas of 1000 ppm was released at different flow rates at the chamber bottom to evaluate the control efficiency of the chamber with the hood at the chamber top, or without the hood by side venting at a large flow rate of 3130 L/min. Numerical results of the control efficiency were verified with the experimental data at the large venting flow rate. The control efficiency of side venting at different flow rates was also investigated. Results show that pollutant dispersion of a metal dry etcher during preventive maintenance can be effectively controlled by side venting at a large flow rate near the chamber top whether the chamber is fully open (without the hood) or with the hood. Good agreement between the experimental data and the simulation results is obtained. The SF6 concentration at the breathing zone was also found to be lower than the detection limit of the FTIR spectrometer. When the side venting flow rate is reduced but maintaining above a fixed value, the pollutant dispersion still can be effectively controlled, and the control efficiency of the chamber with the hood is superior to that of the chamber without the hood.