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AssigneeNissan Chemical Corporation
InventorsTomoya Ohashi, Toyoshiro Yoshida, Suguru Sassa
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A method for producing a coating film-forming composition for lithography, including a step for passing a liquid through a filter cartridge. The filter cartridge is obtained by layering more than one type of filtration base fabrics or winding same around a hollow inner tube, wherein: the fabrics are non-woven fabrics in which metal-adsorbing groups are chemically bonded to polyolefin fibers; the fabrics contain non-woven fabric layers A and B; layer A is configured from polyolefin fibers to which sulfonic acid groups are chemically bonded as metal-adsorbing groups; and layer B is configured from polyolefin fibers to which at least one type selected from among amino groups, N-methyl-D-glucamine groups, iminodiacetic acid groups, iminodiethanol groups, amidoxime groups, phosphoric acid groups, carboxylic acid groups and ethylenediamine triacetic acid groups chemically bonded as metal-adsorbing groups. Thus, the amount of metal impurities that are the cause of minute defects on a wafer can be reduced.
A method for producing a resist underlayer film-forming composition for lithography, the method comprising repeating a series of passing a precursor of the resist underlayer film-forming composition for lithography through a metal removal filter cartridge and subsequently passing the precursor through a fine-particle removal filter cartridge at a flow rate of 10 to 1,000 L/hour for 6 to 144 hours, to reduce metals in the precursor to 0.5 ppb or less,
A method for reducing metals in a precursor of a resist underlayer film-forming composition for lithography, the method comprising repeating a series of passing a precursor of the resist underlayer film-forming composition for lithography through a metal removal filter cartridge and subsequently passing the precursor through a fine-particle removal filter cartridge at a flow rate of 10 to 1,000 L/hour for 6 to 144 hours, to reduce metals in the precursor to 0.5 ppb or less,
Dependencies are inferred from the claim text.