半導體製程廢氣管路中微粒沉降之實廠研究

Field Study on Particle Deposition in the Exhaust Pipeline of Semiconductor Manufacturing Process

本研究目的在驗證半導體廠中乾蝕刻機台廢氣管路外包覆加熱帶以防止微粒附著的效果，研究中考 慮微粒的熱泳、擴散、重力沈降及彎管損失等機制對附著率的影響。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為之，包括一水平管長為120 cm及一彎管半徑為90度彎管，內徑為5.72cm 之不誘鋼管。實驗時不誘鋼管以加熱帶控制管壁溫度為100、80、60及40°C，或管壁不加熱（溫度為25°C)。結果顯示加熱帶不加熱且壁溫維持在25°C時微粒附著率約為4356%，當加熱帶依加熱溫度分別 控制在100、80、60及40°C時，其對應之微粒附著率在氣動直徑為0.04μm至23.24μm間分別約為 11-49%、1942%、2750％及39-58%。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°C大於進氣氣流溫度80°C時，粒徑小於ijim 的微粒附著率會明顯降低。然而，微粒會因為本身帶有電荷而附著或是聚集在一起而沈降附著，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。

The objective of this study is to verify the effectiveness of heating the exhaust pipe to prevent particles deposition in the pipe of a semiconductor dry etching process. The effects of thermophoretic deposition, Brownian diffusion, gravitational setting and bend loss of aerosols particle on deposition efficiency are investigated. The experiment was performed in a horizontal stainless-steel straight pipe (ID= 5.72cm) of 120 cm in length including a 90-degree bend with the bend radius of 20 cm. The pipe is the exhaust of a vacuum pump of a dry etcher in a semiconductor factory. The exhaust gas temperature from the vacuum pump was 80 oC. To heat up the wall temperature, the stainless-steel pipe was covered with a heating tape, and the pipe wall temperature was heated to the temperatures of 100 oC, 80 oC, 60 oC, 40 oC and 25 oC (no heating case). The results show that the deposition efficiency of aerosol particles (aerodynamic diameter ranges from 0.04 μm to 23.24 μm) is 43~56% when the pipe was not heated and the wall temperature, 25 oC, remained the same as the ambient temperature. When the pipe was heated up to 100 oC, 80 oC, 60 oC and 40 oC, the deposition efficiency of aerosol particles (diameter from 0.04 μm to 23.24 μm) is about 11~19%, 19~42%, 27~50% and 39~58%, respectively. The experimental results show that the higher the temperature of pipe wall, the lower the particle deposition efficiency and hence the less frequent cleaning of the pipe is needed. When the pipe wall is heated to a temperature, 100 oC, which is higher than the inlet gas temperature, 80 oC, the particle deposition efficiency for particles less than 1 μm can be reduced substantially. However, complete elimination of particle deposition isn’t available due to the deposition of charged particles and the settling of coagulating particles.