Material Flow Analysis of Water and Wastewater for the Semiconductor Manufacturing Industry
|關鍵字:||半導體物質流;物質流研究;Material Flow Analysis||公開日期:||2007||摘要:||近年來由於工業的蓬勃發展，導致產生工業區內及週邊的用水量不足，必須進行相關的用水調節措施。這種情況隨著各科學工業園區的開發，有日漸嚴重的趨勢，尤其在各科學園區號稱高科技產業的高獲利背後所帶來的高污染、高耗能及高耗水量等高環境成本。在高科技業的耗水量中，以光電產業及半導體產業最為嚴重。因此本研究以物質流分析的方法，探討半導體廠的用水量及廢水產出量，以瞭解水資源在半導體生產活動中的各種流動狀況。分析結果可提供改善的參考，以有效提高半導體廠在水資源上的使用效率。本研究以新竹科學園區的某家半導體廠為實際調查研究的對象，研究中將分析廠區內相關單元的用水及廢水產出量。
本研究發現，每生產一片8吋晶圓，須消耗水約2.8 立方米；每生產一片12吋晶圓，須使用3.0立方米的自來水。由以上數據可觀察到，就用水方面來考量，生產12吋晶圓比生產8吋晶圓更經濟。另外，就目前一噸自來水約12元，而回收一噸化學機械研磨（chemical mechanical polishing, CMP）廢水約需110~135元，廢水廠處理一噸酸鹼廢水需8~10元，含氟廢水約30~35元。就經濟成本上考量，CMP水回收根本不划算。但若再將環境成本也考慮進去的話，則相當程度的回收是需要的；但回收的比例應該訂為多少，則必須考量廢水特性與用水地區的環境條件才算合理。
In recent years, owing to industrial development, the water supply inside and around Taiwan’s science parks has run short to the extent that relevant adjustments in water use have become necessary. This phenomenon is accelerated by the continued development of new science parks, particularly with high profit for parks that are home to the so-called high-tech industries. These industries are usually accompanied with environmental costs of high pollution along with high energy and water consumption. Regarding excessive water consumption required for high-tech industries, optoelectronics and semiconductor industries are the most severe. This study explores water consumption and waste water generation in semiconductor factories through material flow analysis so as to better understand the recycling condition of water supply. The analysis can provide a full-scale examination and constructive suggestions for improvement, enhancing the effective use of water supply in semiconductor factories. The present study targets a typical semiconductor factory in Hsinchu Science Park as the subject, analyzing its water consumption and waste water generation. The results of this study show that approximately 2.8 m3 of water is consumed for every 8 inch wafer produced, and 3.0 m3 of water is needed to manufacture a 12 inch wafer. Based on the above statistical results, from the advantage point of water consumption, producing 12 inch wafers is more economical than 8 inch wafers. In addition, at present a metric ton of tap water is around 12 New Taiwan dollars (NTDs)1, and recycling a ton of chemical mechanical polishing (CMP) waste water costs roughly 110 to 135 NTDs. A wastewater plant spends 8 to 10 NTDs treating 1 ton of acid/alkali-containing waste water, and 30 to 35 NTDs dealing with 1 ton of fluorine-bearing waste water. From a purely economic perspective, the recovery of CMP waste water is not feasible. However, if environmental costs are also taken into consideration, a certain degree of recycling is necessary. In any event, stipulation of the required proportion of recycling should take into account the properties of waste water that is to be treated and the environmental conditions, e.g., water availability, of the water-consuming areas.
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