| 摘要 |
PROBLEM TO BE SOLVED: To enable to efficiently and thoroughly clean the resist of a semiconductor wafer. SOLUTION: The cleaning system has with a cleaning device for cleaning a work 1 to be cleaned using a persulfuric acid solution as a cleaning liquid; electrolytic reaction devices 17, 27 and 37 for generating persulfuric ions from sulfate ions by an electrolytic reaction to regenerate a persulfuric acid solution; circulation lines 13, 23, 33, 15, 25 and 35 for circulating the solution between the cleaning device and the electrolytic reaction devices; and liquid transferring pumps 14, 24 and 34. The cleaning device has a plurality stages of cleaning tanks 10, 20 and 30 for successively cleaning the work to be cleaned, and is set so that the concentration of sulfuric acid of the cleaning liquid in the cleaning tank is low as the lower stage. Preferably, the concentration of sulfuric acid of the first stage is 17 M or more, and the concentration of sulfuric acid of the second stage and lower is in a range of 8 M-15 M. Contamination such as resist is efficiently eliminated with concentrated sulfuric acid having high cleaning effect in the cleaning tank in a front stage side and for detailed portions, and contamination is efficiently eliminated with sulfuric acid having low viscosity in a rear stage. COPYRIGHT: (C)2007,JPO&INPIT
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