半導體製程廢氣中微粒沉降之實廠研究

Abstract

摘 要 本研究目的在驗證半導體廠中廢氣管路外包覆加熱帶以防止微粒附著的效率，實驗時控制加熱帶加熱溫度，以兩台MOUDI多階衝擊器同時在測試管線之進口及出口採樣點收集微粒，求得各加熱溫度下微粒附著沉積率。本實廠實驗選擇在半導體廠乾蝕刻機台之真空泵後端廢氣管路一水平管長為1200mm及一90度彎管，彎管半徑為200mm，管徑為57.2mm之不□鋼管於層流狀態下進行測試。實驗條件包含氣懸浮微粒通過不□鋼管具加熱帶加熱溫度控制為40、60、80、1000C及加熱帶不加熱溫度為250C (室溫)兩種。結果顯示加熱帶不加熱時其微粒附著效率約為41~57%，當加熱帶依加熱溫度分別控制在400C、600C、800C及1000C時，其對應之微粒附著效率分別約為40~58%、31~54%、17~43%及6~20%。 實驗結果發現，隨著管壁加熱溫度升高，微粒沉積率會愈低，因此清理管線的頻率也會降低。當管壁加熱至溫度100 oC大於進氣氣流溫度80 oC時，粒徑小於1mm的微粒附著效率會明顯降低。然而，微粒會因為靜電而沈降附著或因其他機制而附著，所以要使用加熱帶加熱管壁溫度完全免除微粒的附著是很難達到的。

Abstract The objective of this study is to verify the method of covering exhaust pipe with heating tape to prevent particles from deposition and to evaluate the deposition efficiency of aerosol particles in the exhaust pipe of the semiconductor dry etching process. The effects of thermophoretic deposition, Brownian diffusion, gravitational settling and impaction loss of aerosol particles on deposition efficiency are also investigated. The experiment was performed in a horizontal stainless-steel pipe including a 90-degree bend with a bend radius of 200 mm and a straight tube of 1200 mm in length, located after the vacuum pump of a dry etcher in a semiconductor factory. The inner diameter of the pipe is 57.2mm. The experiment consists of two conditions. One is that aerosol particles pass through stainless-steel pipe covered with heating tape and operated at temperature of 40、60、80 and 1000C. The other is that the temperature was only keeping at 250C (ambient temperature) under laminar flow condition. The results showed that the deposition efficiency of the aerosol particles is 41~57% at ambient temperature. When the heating tape temperature was at 40、60、80 and 1000C, the deposition efficiency of the aerosol particles was about 40~58%, 31~54%, 17~43% and 6~20%, respectively. It is suggested that, the deposition efficiency of particles will be lower by heating the pipe wall at a higher temperature. With an increasing pipe wall temperature, the deposition efficiency decreases and the pipe cleaning will be less frequent. When the pipe wall is heated to a temperature of 100 oC, which is higher than the inlet gas temperature, 80 oC, the submicron particle deposition efficiency will be reduced substantially. However, it is believed that complete prevention of particle deposition on the wall can¢t be achieved only by increasing the tape temperature due to particle deposition caused by of electrostatic attraction and or other deposition mechanisms.