區域洗滌設備異常事件失誤模式探討-以某半導體廠為例

Abstract

半導體廠因製程之需要而使用大量危險及有害化學物品，而這些化學品皆為具有燃燒性、爆炸性、毒性等高度反應性的危害物質，可直接或間接對人體與環境造成一定之損害。而本研究統計某半導體廠內，2006 ~ 2010年所發生之異常事件，發現在區域洗滌設備（Local Scrubber）所佔比例為最高252件，約占百分比25％。本研究針對區域洗滌設備之異常事件進行統計與探討，發現氣體洩漏事故佔百分比62％，液體洩漏事故佔百分比36％，因煙霧產生導致偵煙感知器動作佔百分比2％。而氣體洩漏事故之原因，所占比例最多者為管路阻塞，約為41％；液體洩漏事故原因最多者，則為內部元件故障，包括有供水電磁閥，排水幫浦，液位計故障等，所占百分比為30％。後續針對各異常元件進行失效模式與影響分析（FMEA）後，得知氣體洩漏事故發生之失效因子共有36項，其每小時失效機率最高為進氣管路阻塞的7.5×10-4，等。液體洩漏事故發生之失效因子共有27項，其中每小時失效機率最高為供水電磁閥故障的3.4×10-4；煙霧事故發生之失效因子共有3項，其中每小時失效機率最高為進氣管路阻塞與作業管理缺失的4.6×10-5。而後針對各失效因子訂立預防改善對策，並將改善前後進行差異性比較。結果如氣體洩漏事故中，其失效因子管路阻塞之失效機率從每小時7.5×10-4下降至3.4×10-4。液體洩漏事故中，其失效因子供水電磁閥故障的失效機率從每小時3.4×10-4下降至2.3×10-4；煙霧事故失效因子，管路阻塞的失誤機率從每小時4.6×10-5下降至0，故得知其行政管控與部份工程改善有一定之成效。本文並探討燃燒水洗式互鎖功能(Interlock)安全設計，至少需具備九項硬體安全裝置互鎖功能，而吸附式區域洗滌設備，則至少需具備五項硬體安全裝置互鎖功能。最後本研究並參考國內外安全規範（SEMI、NFPA）指引，建立區域洗滌設備標準規範提供相關業界參考。

Semiconductor plants often need to use large quantities of dangerous and harmful chemicals during the manufacturing process, and since these chemicals may be flammable, explosive, toxic or other highly reactive dangerous substances, they tend to cause a certain degree of harm to the human body and the environment, both directly and indirectly. A survey was conducted by this study in a semiconductor plant on abnormal accidents from 2006~2010, the local scrubber equipment was found to experience the highest rate, 25%, of the 252 incidents that occurred. Furthermore, when the abnormal accidents of the local scrubber were analyzed and investigated, gas leakage accidents were found to account for 62% of the events; liquid leakages, 36%; and detector and sensor actions caused by smoke, 2%. Pipeline plugging accounted for the highest rate of gas leakage accidents, at approximately 41%; internal component malfunctioning, including water supply solenoid valve, drainage pump and fluid level gauge failures, etc., accounted for the highest rate, approximately 30%, of liquid leakage accidents. When various abnormal components were analyzed by using Failure Mode and Effect Analysis (FMEA), the failure factor caused by gas leakage accidents was found to cause a total of 36 events, with air intake pipe blockage accounting for the highest hourly failure rate of 7.5×10-4. A total of 27 failure factors were found in liquid leakage accidents, with the highest hourly failure rate of 3.4×10-4 being caused by water supply solenoid valves; a total of 3 failure factors were found in smoke accidents, with the highest hourly rate of 4.6×10-5 caused by air inlet pipe blockage and operation management faults. The prevention and improvement measures were then employed for various failure factors, whose failure rates were compared with those before the improvements. The hourly failure rate of failure factors in gas leakage accidents caused by pipeline blockage fell from 7.5×10-4 to 3.4×10-4. In the failure factor of liquid leakage accidents, the hourly failure rate caused by water supply solenoid valve malfunctioning dropped from 3.4×10-4 to 2.3×10-4 ; and in the failure factor of smoke accidents, the hourly failure rate caused by pipeline blockage plummeted from 4.6×10-5 to zero. Therefore, administrative control and sectional engineering improvements were shown to yield effective results. This study also investigated the safety interlock design of the burn-wet scrubber system and found that it required at least five safety devices on the interlock function of hardware alone. Finally, the domestic and overseas SEMI and NFPA safety guidelines were studied to establish the standard norms on regional washing equipment, which serve as a reference for relevant industry sectors.