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In this study, A phenomenon of high peroxynitrite generated in purge gas in purge head outlet of RSP SMIF-POD Charger
was found. A superior purification CDA("CDA" is abbreviated from Clean Dry Air) continuous purge system has been used
in 193nm ArF reticle chemical free preservation process for mask Haze control. Ion Chromatography(IC) and Gas
Chromatography Mass Spectrometry(thermal desorber GC-MS) methods are used to analyze and verify inorganic ion and
volatility organic compound cleanliness of purge gas, respectively. After IC analysis, high nitrate ion concentration was
detected in UPW("UPW" is abbreviated from Ultra-Purification Water).
As a result of this study, It is confident of presuming that high peroxynitrite contamination in purge gas in purge head
outlet was caused by the blow type in-line gas ionizer, high potential(approximate 2KV) needle discharge influence on
the inside of purge piping of Charger. After bypass in-line gas ionizer apparatus, the IC analysis result has a tendency
towards a diminution in peroxynitrite that nitrate ion was not detected in UPW at all. At the same operation condition, if
purge gas replace by superior purification AN2(A Class Nitrogen) and the inference conjectured that high ammonium ion
response in UPW would take place.
According to our study, superior purification CDA passed through the emitter tip of blow type in-line gas ionizers and
under high potential needle discharge influence, high peroxynitrite concentration was generated in purge gas in purge
head outlet of Charger. Due to the generation of peroxynitrite ion contamination in purge gas, it was not suitable to apply
in the prevention of ESD damage of mask pattern in superior purification CDA(Clean Dry Air) continuous purge system.
In this study, we also unexpectedly find that the blow type in-line gas ionizer with thermoplastic conductive tube resulted
in purge gas a large number of volatility organic compounds(VOCs) contamination. VOC outgassing was generated from
the inner walls of conductive tube which the most neighbor on the emitter tip, and heated by the power dissipation of
needle discharge influence of corona ionizers.
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