| 摘要 |
PROBLEM TO BE SOLVED: To effectively and securely clean an electronic material substrate for which a highly cleaned surface is required, such as a silicon wafer, liquid crystal glass substrate, and photomask substrate. SOLUTION: A system comprises a cleaner (cleaning tank 1) for cleaning a material to be cleaned (semiconductor substrate 30) using a sulfuric acid solution 3 as a cleaning solution, a storage (storage tank 10) for storing a cleaning solution for cleaning in the cleaner, an electrolytic reaction unit (electrolytic reaction tank 20, DC power supply 22) for manufacturing a persulfate solution by producing persulfate ion from sulfuric acid ion contained in the solution by electrolytic reaction, and a circulation line (feed pipe 14a, return pipe 14b) for circulating the solution between the storage section and the electrolytic reaction unit. Preferably, a concentrated sulfuric acid solution of sulfuric acid concentration of 8 M to 18 M and temperature of 130 to 200°C is produced in the cleaner which is changed to a solution of temperature 80 to 130°C or lower in the storage. COPYRIGHT: (C)2007,JPO&INPIT
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