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8 June 1998 Contamination monitoring for ammonia, amines, and acid gases utilizing ion mobility spectroscopy (IMS)
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The effect of ammonia (NH3) and n-methyl pyrrolidinone (NMP) contamination on chemically amplified DUV resists is well documented. Other amines and related compounds are under suspicion as well. In addition, the concentration levels that are of concern have steadily decreased from approximately 10 ppbv down to levels as low as 0.1 ppbv. While some techniques such as ion chromotagraphy (IC) have been demonstrated to have limits of detection at these levels, the analysis times are rather long and cumbersome. This paper describes the use of IMS to perform these measurements, in a totally automated, continuous instrument. IMS is a simplified time-of-flight technique that requires no liquid reagents and has been demonstrated to be a reliable method for monitoring for ammonia and NMP in cleanrooms. This paper demonstrates the ability of the technique to monitor for amines such as dimethylamine, methylamine, methanolamine, ethanolamine, diethanolamine, butylamine and others. Detection limits of 0.1 ppbv and below are clearly demonstrated. Also discussed are methods of monitoring multiple points with a single analyzer. Ability to detect corrosive gases such as hydrogen fluoride (HF), hydrogen chloride (HCl), sulfur dioxide (SO2), sulfur trioxide (SO3), nitrogen dioxide (NO2), chlorine (Cl2), bromine (Br2), phosphoric acid (H3PO4) are also demonstrated.
© (1998) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Tad Bacon, Kurt Webber, and Ronald A. Carpio "Contamination monitoring for ammonia, amines, and acid gases utilizing ion mobility spectroscopy (IMS)", Proc. SPIE 3332, Metrology, Inspection, and Process Control for Microlithography XII, (8 June 1998);

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