Metallic contamination reduction in polymer solution using membrane purification technology

As the patterning resolution of semiconductor manufacturing increases, so does the need to remove critical defects from the photochemical supply chain. In particular, metallic contaminants have been known to lead to various types of defects such as cone defects that contribute to significant yield loss(1). Hence, control of metallic contaminants is critical for these next generation lithography processes. Previous work has introduced the Purasol (TM) LS2 solvent purifier, capable of superior metal reduction in a wide range of photochemical solvents(2). Current work focuses on purification of polymer solutions, a key intermediate material in the photochemical ecosystem. We present data detailing the ability of the LS2 purifier to remove metals from a poly-(4-hydroxystyrene) (PHS) polymer solution. Purifier membrane in coupons as well as an LS2 purifier device are used in a series of experiments to investigate the metal removal efficiency in the polymer solution as a function of various experimental parameters. Metal removal is quantified using ICP-MS (inductively coupled plasma mass spectroscopy) measurements. In addition, we also present customer data demonstrating the effectiveness of the LS2 in purifying polymer solutions to reduce defects that degrade yield performance.