Abstract: Chemically amplified DUV photoresists have a sensitivity to certain airborne chemical contaminants. Processing these resists requires control of the environment within the process tooling. This study explores the contamination threshold levels to meet minimum established lithography criteria as well as the effectiveness of the equipment in providing such an environment. A DUV lithography cluster consisting of a SVGL MICRASCAN-II linked to an SVG Series 90 track are the platform for this study. Both the stepper and track utilize Donaldson stacked carbon filters, each is sized to design air flow rate. Measurement and control of two (2) known contaminants, n-methyl2-pyrolidone (NMP) and ammonia (NH$- 3$/), are investigated in the stepper chamber, the track chamber, and the surrounding environment. Gas chromatography (GC) and ion mobility spectrometry (IMS) are used to measure NMP and NH$-3$/ levels, respectively, and provide the basis for the data presented. Criteria for resist profile, critical dimension (CD) and post exposure delay (PED) in a single layer resist system i.e., without resist top-coat (RTC), were set such that contamination effects are of no consequence. Contaminant threshold levels to meet this lithography criteria have been determined. Data that underscores the trade-off between having a single purpose filter or a dual purpose filter design that removes both NMP, an organic, and NH$-3$/, an inorganic, are analyzed. The effectiveness (efficiency and life time) of this dual purpose filter in reducing the contaminants to low enough levels for maintaining lithography acuity, as established by the criteria, are summarized. A cost analysis highlighting the economic trade-off of using either RTC in a non-filtered environment or providing a conducive filtered environment for single layer resist processing are analyzed. Conclusions based upon data from ambient conditions, both inside and outside the lithography cluster and the performance of the equipment are made. Recommendations are made on what constitutes a `clean' environment and when the use of RTC may become necessary. !5
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