Treatment of Wastewater Containing H2O2 in Semiconductor Fabrication by Catalase Dosing
|關鍵字:||水處理;過氧化氫酶;過氧化氫;CMP;water treatment;catalase;Hydrogen peroxide;CMP|
|摘要:||半導體製程中以CMP與wet etching兩大製程，使用大量超純水進行晶圓之清洗，而清洗與蝕刻製程所使用之RCA 清洗配方FPM、APM、HPM皆含有H2O2，含銅CMP製程所使用之研磨液也含有H2O2，上述產生之廢水又以含銅CMP製程中，所排放之廢水較為難處理，因其廢水中含有相當多種類之研磨液，包含許多奈米顆粒、界面活性劑與H2O2。而目前業界多採用化學混凝加藥處理，但如水中H2O2 濃度太高，易導致沉澱槽膠羽上浮，影響回收水水質，如能先將廢水中之H2O2去除，並穩定化學混凝加藥進流濃度，對於該股廢水回收之水質、水量，有相當大的助益，且能有效提升全廠回收率。
研究結果顯示過氧化氫酶對於水質之pH、溫度與反應基質濃度等皆會影響反應去除效率，實驗結果顯示反應水體水溫在35℃下，pH 5與 pH 9反應活性較不受影響，於水體導電度之實驗，結果顯示在反應20分鐘時，導電度5000、20000 μS/cm下反應去除效率為90.6% 與 95.0%，差異4.6%
此外水質取樣分析CMP 與 Cu CMP 兩股廢水皆能符合過氧化氫酶反應所需之最佳環境條件，然不同之過氧化氫酶反應活性，對於 H2O2 之去除效率有相當大之差異，在相同加藥量下，對於H2O2 去除效率相差可達40%。除了適當的pH、溫度等條件，對於過氧化氫酶的活性品質需特別注意，避免使用低活性過氧化氫酶而提高加藥量，造成藥品費用的增加。|
Among the processes for manufacturing semiconductors, the circuit multiproject CMP and wet-etching processes involve using a considerable amount of ultrapure water for cleansing wafers. During the cleansing and etching process, FPM、SPM、HPM and APM present in Radio Corporation of America (RCA) cleaning solutions, both contain H2O2. The grinding fluid used in the copper-containing (Cu-CMP) also contains H2O2. Of the aforementioned processes, the waste water produced during Cu-CMP is the most difficult to recycle because this water contains several grinding fluids, including numerous nanoparticles, surfactants, and H2O2. Currently, the industrial field has mostly adopted chemical coagulation for water treatment. However, when the concentration of H2O2 in the water is excessively high, the floc in the precipitation tank easily floats upward, thereby influencing the quality of the recycled water. If the H2O2 in waste water can be removed in advance to stabilize the inflow concentration of coagulants, the quality and quantity of recycled waste water can be substantially improved, effectively enhancing the recycle rates of an entire water treatment plant. In this study, catalase was used because it can dissociate H2O2 into water and oxygen. A jar test method designed to be combined with various reaction conditions was employed to determine the limitations of catalase addition and identify the optimal iv amount to be added. The results showed that the pH value, temperature, and reactive substrate concentration in water affected the catalase reactions and H2O2 removal rates. The experimental results revealed that water temperatures below 35°C and at pH 5 and pH 9 exerted minimal influence on removal rates. In the electrical conductivity experiment of the water body, the results showed that the reaction and removal rates after 20 min of reaction at a conductivity of 5000 μS/cm and 20000 μS/cm were 90.6% and 95.0%, respectively, yielding a difference of 4.6%. In addition, in the water quality sampling analysis, the two currents of waste water from CMP and Cu-CMP satisfied the optimal environmental conditions for catalase reactions. However, differing catalase reactivity generated considerable differences in H2O2 removal rates. When the amount of chemical added was identical, the H2O2 removal rates could engender a difference of 40%. Therefore, in addition to considering appropriate pH and temperature conditions, researchers must particularly monitor the activities of catalase and avoid using low-activity catalase, which may increase the amount of chemicals required during water treatment and thereby increase relevant expenditures.