Saksatha Ly

Targeted removal of metallic contamination from lithography solvents using membrane purifiers

Metal ions in photoresists and solvents pose an ever greater contamination problem in photolithography’s advanced applications. The reduction of metal contaminants is critical in the entire photochemical supply chain. In this paper we demonstrate that two novel membrane purifiers dramatically reduced the metal contents in a range of organic solvents. These solvents are used for photoresist manufacturing and for wafer surface and dispense line rinse in track tools. The impact of flow rate and metal concentrations in the feed on the metal removal efficiency of the purifiers is presented. Furthermore, a study to determine the dominant mechanism of metal reduction in solvents is proposed.

Development of novel purifiers with appropriate functional groups based on solvent polarities at bulk filtration

Weak-polar solvents like PGMEA (Propylene Glycol Monomethyl Ether Acetate) or CHN (Cyclohexanone) are used to dissolve hydrophobic photo-resist polymers, which are challenging for traditional cleaning methods such as distillation, ion-exchange resins service or water-washing processes. This paper investigated two novel surface modifications to see their effectiveness at metal removal and to understand the mechanism. The experiments yielded effective purification methods for metal reduction, focusing on solvent polarities based on HSP (Hansen Solubility Parameters), and developing optimal purification strategies.