| Summary: | 碩士 === 國立交通大學 === 環境工程所 === 90 === Inorganic airborne molecular contaminants are important sources of contamination in cleanroom air that may cause device failure and decrease product yield. In this study, the optimal sampling conditions of two types of silica gel tubes as well as the impinger sampler for measuring acidic contaminants in cleanroom air were investigated. In addition, the optimum sampling condition for measuring ammonia by using the impinger sampler was also studied.
The experimental results indicated that silical gel tube has the best collection efficiency under flowrate of 200~300 ml/min and the sample volume must over 400 liter for effective sampling in cleanroom. The impinger sampler had non-obvious decrease in absorbent volume (<5%) when the sampling flowrate was controlled to below 300 ml/min. The optimal sampling condition of impinger for acidic contaminants and ammonia were at sample flowrate of 50 and 300 ml/min, respectively, sample time of 24-hr.
The results of actual cleanroom sampling showed that due to high interferences from residue contaminants in silica gel tubes, they were not suitable for low concentration cleanroom sampling. The interference from residue contaminants in silica gel was especially obvious for SUPELCO ORBO-53 sampler. The most suitable sampler for collecting acidic airborne contaminants in cleanroom air was the impinger sampler. It had the high recovery for HF of exceeded 90% in 60 ml absorbent and 100% for other acidic species in 30 ml absorbent. Beside, Impinger has the advantages of negligible interference from blank samples. The sampling results from the impinger sampler showed that the concentrations of HF, HCl and NH3 were exceeded 1,000n mol/m3. So these three species were the major inorganic airborne molecular contaminants in the cleanroom air.
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