US Patent 7585418 Lithographic mask and manufacturing method thereof

Cleaning is carried out by using a sulfuric acid type detergent at a resist stripping and cleaning step (step 5) in a semitranslucent portion forming process and a resist stripping and cleaning step (step 10) in a shielding band forming process, and a sulfuric acid removing step of partially or wholly removing a surface layer portion in a pattern into which a sulfate ion is adsorbed is then carried out to effectively remove the adsorbed sulfate ion.