Assessment of the REWORK operating environment for color filter glass substrate process
|關鍵字:||光電產業環境;彩色濾光片;REWORK;氣態分子污染物;氯離子;TFT-LCD environment;color filter;REWORK;Airborne molecular contamination;chloride ions|
本研究探討氧化銦錫透明導電層(Indium Tin Oxide, ITO) REWORK製程作業區機台運轉過程與預防保養作業時對人員危害性及環境設備腐蝕之影響，研究方法採用衝擊瓶來收集環境中氣態分子污染物，並搭配離子層析儀進行分析。研究結果顯示，ITO REWORK製程作業區於玻璃基板再生回收清洗作業時的排氣風管中氯離子濃度可高達54592 ppbv；而於該製程區設備正常運轉時進行空氣中氯離子濃度採樣分析，所測得氯離子濃度介於12~25 ppbv之間，其主要污染源為藥液儲存槽區；此外在預防保養作業期間因會開啟蝕刻槽體護蓋作業，主要污染逸散源則為蝕刻槽體區，此時環境空氣中氯離子濃度亦明顯上升，所測得氯離子濃度介於90~282 ppbv。
Color filters are the key components in the TFT-LCD, and the glass substrate material has the highest share of the cost for manufacturing color filters. There are some defective glass substrate products being produced from the color filter production process, they can be reused through REWORK process thus effectively reduce the manufacturing costs and avoid directing scrap waste that pollutes the environment. However, the wet etching procedure is employed in the REWORK process which uses highly corrosive HCl liquid chemicals. Under poor machine equipment and environmental management conditions, the chloride ionic pollutants would emit to the clean room environment and cause equipment corrosion problem. Under worse cases, it could even result in harmful effects on the workers. This study intends to monitor the chloride ions emitted to the clean room environment from ITO (Indium Tin Oxide) REWORK process area. The chloride airborne molecular contamination in the air environment was sampled by impingers and then analyzed by an ion chromatographer. The results show that the chloride ion concentration was up to 54592 ppbv as measured from the exhaust pipe of the recycling-wash operation of ITO REWORK process. In the process bay area and under normal equipment operation, the chloride ion concentrations in the clean room air were measured to be in the range of 12~25 ppbv. In addition, during the preventive maintenance operation, the etch tank cover was opened and the chloride ion concentrations were increased to be in the range of 90~282 ppbv. According to the analysis of the samples, the measured chloride concentrations can be well below the published ambient standards of Labor Affairs. It can also be complied with the recommended standards of Semiconductor Equipment and Materials International for the flat panel display industry. But the cleanliness of equipment and its parts can still cause bad effects in the long run. There is no good alternative liquid for replacing the HCl chemical yet. Thus the selection of corrosive resisting material as well as proper inspection and cleaning frequency are both necessary to prevent the accumulation and corrosion of choride pollutants on the equipments.
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