UV Photochemistry in the Exposure Chamber Environment of Optical Lithographic Tools

Okoroanyanwu, P. Kunze, K. Al Shamery, J. Romero, and J. Bernard, Impact of photoinduced species in O2 containing gases on lithographic patterning at 193 nm wavelength Proc. SPIE 4691, 746 (2002). 

Although contamination control is implemented in these exposure tools with on-board purge control units, which are equipped with gas purifiers that remove contaminants such as H2O, O2, CO, CO2, hydrocarbons, H2, and sulfur compounds, these control units are oftentimes not 100% efficient. Typical benefits of molecular contamination control include improved process yield and greater process control. 

---