Measurement of Inorganic Acidic Gases and Particles from the Stack of Semiconductor and Optoelectronic Industries

Abstract

A method for sampling inorganic acids in the exhaust gas of semiconductor and optoelectronic industries was developed by using a porous metal denuder and an ion chromatograph analysis. The sampler consists of a Teflon filter to collect inorganic acidic aerosols followed by two coated porous metal discs for sampling inorganic acidic gases. The second disc was used to check if the gas broke through the first disc. The method detection limit of the sampler is appropriate for sampling the exhausted gas at semiconductor or photoelectric industries. Test results indicated that the calibration curves had good coefficients of correlation, and the concentrations of the laboratory and field blanks were found to be lower than the method detection limit. For the semiconductor and optoelectronic industries, the total concentration of acidic gases and particles for hydrofluoric acid, hydrochloric acid, nitric acid, phosphoric acid, and sulfuric acid was found to be 85–999, 40–820, 21–223, ND (not detectable)–404, and 49–535 µg/Nm³ (at 0°C, 1 atm), respectively, by using the new method. The porous metal denuder is compact in size, sensitive in detection, and suitable for sampling several inorganic acids simultaneously in the exhausted gas for the semiconductor or photoelectric industries.

Keywords:

• Inorganic acids
• Semiconductor and optoelectronic industries
• Porous metal denuder
• Detection limit

Acknowledgment

The authors would like to thank the National Institute of Environmental Analysis of Environmental Protection Administration, Taiwan, Republic of China, for the financial support of this research under Contract No. EPA‐91‐1601‐02‐08.