| 摘要: | 矽晶圓製造業在半導體產業供應鏈中，扮演著材料供應商的角色，主要生產製造各吋別矽晶圓片，並提供積體電路製造業或磊晶廠作為後續產品製造，矽晶圓片製造程序有長晶、分段、切片、倒角、研磨、酸蝕刻、清洗、拋光等程序。因原物料其中之一切削油，主成分為二乙二醇(Diethylene glycol, DEG)、其二酸蝕刻液中混酸成分之醋酸(Acetic acid)，第三具有黏著功用之溶劑，因初始沸點低於250℃，為「揮發性有機物空氣污染管制及排放標準」認定之揮發性有機物，而須依「公私場所固定污染源申報空氣污染防制費之揮發性有機物(VOCs)之行業製程排放係數、操作單元(含設備元件)排放係數、控制效率及其他計量規定」[1]中所公告排放係數計算排放量，矽晶圓製造業因無適用之製程類別係數，僅能以1,000.000V質量平衡法或引用積體電路製造業(2.24kg/m2)排放係數估算排放量作為上繳空氣污染防制費之依據，實則有高估及無法獲得合理排放量之問題。
本研究對象為半導體業矽晶圓製造程序，依據行政院環境保護署公告「固定污染源揮發性有機物(VOCs)自廠係數(含控制效率)建置作業要點」，建置該廠VOCs排放自廠係數。作為本研究作業程序分述如下1.以兩種不同廠牌切片機切片作業，於切片作業中機台上方排氣直接檢測揮發性有機物排放量。2.切片作業前須使用兩種黏著劑混合後將矽晶圓棒與塑膠墊塊及石墨墊塊進行貼合之貼合作業，以及使用單一黏著劑將矽晶圓片貼附於陶瓷盤上之貼片作業，共計三種黏著劑揮發性有機物含量檢測。3.前段製程須利用含有醋酸之混酸蝕刻矽晶圓片表面以去除損傷層，在蝕刻作業過程中於機台上方排氣直接檢測醋酸排放量4、酸蝕刻廢水排放至廢水廠經由貯槽至中和調勻處理過程的醋酸逸散排放量檢測。綜合上述四項作業並依照環境檢驗所公告之檢測方法可測得各項作業揮發性有機物排放量，並與檢測期間產能之關係，最終可得到該研究廠總產能之單位面積VOCs排放強度之加總結果，則可視為合理反應實際排放量之製程揮發性有機物排放係數。
;In the semiconductor supply chain, silicon wafer manufacturing plays an important role in producing blank wafers of various sizes for IC or EPI manufacturers. The processes for silicon wafer manufacturing include crystal growth, crystal sectioning, edge grinding, wafer lapping, acid etching, cleaning, polishing, etc. Certain materials used in these processes such as slicing oil, acetic acid, and solvents in ingot/wafer mounting have initial boiling points below 250oC. Hence they are classified as Volatile Organic Compounds according to Taiwan Environmental Protection Administration’s “Air Pollution Management Regulations and Emission Standards for Volatile Organic Compounds”. Relevant regulations further declare that the air pollution control fees are to be collected based on the type and quantity of air pollutants. However, the wafer manufacturing industry is not officially classified as an industrial sector such as the semiconductor industry. It is forced to adopt the method of mass balance of 1,000.000 V or the emission factors used in the IC industry, 2.24 kg/m2, to estimate the emission quantity as the basis for air pollution control fees, which is actually overestimated and unreasonable.
This study attempts to estimate VOCs emission factors for the wafer manufacturing processes by following Taiwan EPA promulgated “Self-Establishment of VOCs Emission Factors (Including Control Efficiency) by Stationary Pollution Sources”. Procedures adopted in this study are as follows.
1. Conduct direct measurement of VOCs emission quantities on top of two wire saws of different manufacturers while they are running.
2. Use two mixed adhesives to mount the ingots onto resin/graphite beam before slicing, and another adhesive to mount the wafers onto the ceramic block before wafer being polished. VOCs emissions for these three adhesives are measured.
3. In the front-end process, acetic acid is mixed with other chemicals to remove the damaged layers of wafers. Direct measure of acetic acid emission quantities for the acid etching process is measured.
4. Fugitive emission of post-etching waste water through deposit tanks to
neutralization/equalization tanks in the waste water treatment unit is also measured.
The total amount of measured VOCs emission quantities of the four processes is the summation of the individual emission quantity of above mentioned processes. The total VOCs emission quantity divided by the total capacity equivalent surface area for the wafer manufacturing processes will yield the VOCs emission factor. |
