Gas dissolved in liquids such as photoresist comes out of solution as bubbles after the liquid experiences a pressure drop
in a dispense train and may cause on-wafer defects. Reservoirs in the dispense train can assist in removing bubbles but
are incapable of effectively removing dissolved gas. This study demonstrates the importance of maintaining the amount
of dissolved gas in a liquid below a critical value to reduce bubbles generated after a pressure drop in the dispense train
occurs. The methodology used to quantify dissolved gas during liquid dispense cycle using gas chromatography is
discussed. The amount of dissolved gas is correlated to the amount of bubbles downstream of a pressure drop. This study
also analyzes sources of bubbles in the dispense train and techniques to mediate the sources.
"Dissolved gas quantification and bubble formation in liquid chemical dispense", Proc. SPIE 7520, Lithography Asia 2009, 752039 (14 December 2009); doi: 10.1117/12.852209; https://doi.org/10.1117/12.852209