奈米微氣泡浮除技術於半導體工業化學機械研磨廢水回收之實廠應用

Abstract

半導體業中之化學機械研磨 (Chemical mechanical polishing, CMP) 廢水中主要含有奈米級之矽氧化物懸浮微粒，其具有相當穩定分散的能力。目前大部分廠商多利用傳統之化學混凝/沈澱來處理，但這個方法需要建造大面積的沈澱槽，且需要較長的過濾時間來分離。 本研究係利用奈米微泡浮除技術配合實驗設計中之 2k 因子設計及中央合成設計進行浮除實驗，對 CMP 廢水進行回收處理，旨在探討操作參數對廢水處理效果之影響，找出最適操作條件，並初步估計處理成本，用以評估化學機械研磨廢水回收再利用技術之可行性。 由研究結果顯示，利用多元氯化鋁混凝並添加油酸鈉作為捕集劑劑處理CMP 廢水已能有效去除濁度、總固體物、總有機碳及總矽等污染物。此外，在考量成本與水質下，以多元氯化鋁濃度 50 ~ 60 mg/L as Al，pH 調整至 4 ~ 5，捕集劑濃度為 5 ~ 10 mg/L，水力停留時間為 1 小時，迴流比為 10 ~ 20% 為最適之操作條件範圍。本研究所得到之成果將可作實廠操作之參考。

Chemical mechanical polishing (CMP) wastewater in semiconductor manufactory is characterized as extremely stable dispersion of nano-size silica. Generally, coagulation- flocculation and sedimentation processes are employed by most of the semiconductor manufacturers in Taiwan. This treatment needs large area for sedimentation tank and takes long time to separate the precipitate. The Nano-sized bubble flotation technology with 2k Factorial Design and Central Composite Design of experimental design were used for treatment and reclamation of the CMP wastewater. The purpose of this study was to examine the effects of the operational variables on the efficiency of wastewater treatment and to find the optimization of the process performance. The results showed that the CMP wastewater could be treated suitably by using polyaluminum chloride as an activator and sodium oleate as a collector. The optimal operating conditions were as follows: concentration of polyaluminum chloride was between 50 and 60 mg/L as Al, the concentration of sodium oleate was between 5 and 10 mg/L, the pH values of the wastewater was between 4 and 5, the hydrolic retention time was 1 hour and the recycle ratio was between 10 and 20%. After this study, the experience gained in this study is useful for commercial process.