Monitoring airborne molecular contamination: a quantitative and qualitative comparison of real-time and grab-sampling techniques

Aaron M. Shupp; Dan Rodier; Steven Rowley

doi:10.1117/12.707776

5 April 2007 Monitoring airborne molecular contamination: a quantitative and qualitative comparison of real-time and grab-sampling techniques

Aaron M. Shupp, Dan Rodier, Steven Rowley

Author Affiliations +

Proceedings Volume 6518, Metrology, Inspection, and Process Control for Microlithography XXI; 65183Z (2007) https://doi.org/10.1117/12.707776
Event: SPIE Advanced Lithography, 2007, San Jose, California, United States

Abstract

Monitoring and controlling Airborne Molecular Contamination (AMC) has become essential in deep ultraviolet (DUV) photolithography for both optimizing yields and protecting tool optics. A variety of technologies have been employed for both real-time and grab-sample monitoring. Real-time monitoring has the advantage of quickly identifying "spikes" and upset conditions, while 2 - 24 hour plus grab sampling allows for extremely low detection limits by concentrating the mass of the target contaminant over a period of time. Employing a combination of both monitoring techniques affords the highest degree of control, lowest detection limits, and the most detailed data possible in terms of speciation. As happens with many technologies, there can be concern regarding the accuracy and agreement between real-time and grab-sample methods. This study utilizes side by side comparisons of two different real-time monitors operating in parallel with both liquid impingers and dry sorbent tubes to measure NIST traceable gas standards as well as real world samples. By measuring in parallel, a truly valid comparison is made between methods while verifying the results against a certified standard. The final outcome for this investigation is that a dry sorbent tube grab-sample technique produced results that agreed in terms of accuracy with NIST traceable standards as well as the two real-time techniques Ion Mobility Spectrometry (IMS) and Pulsed Fluorescence Detection (PFD) while a traditional liquid impinger technique showed discrepancies.

Citation Download Citation

Aaron M. Shupp, Dan Rodier, and Steven Rowley "Monitoring airborne molecular contamination: a quantitative and qualitative comparison of real-time and grab-sampling techniques", Proc. SPIE 6518, Metrology, Inspection, and Process Control for Microlithography XXI, 65183Z (5 April 2007); https://doi.org/10.1117/12.707776

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