Patent ID: 8187449

Claim:
A cleaning method by electrolytic sulfuric acid, comprising: as a first step, supplying a first sulfuric acid solution from outside into a sulfuric acid electrolytic cell having an anode compartment separated from a cathode compartment by a diaphragm, a conductive diamond anode installed in said anode compartment, and a cathode installed in said cathode compartment; and performing electrolysis to form a first electrolytic sulfuric acid containing said first sulfuric acid solution and oxidizing agent in said sulfuric acid electrolytic cell; as a second step, supplying a second sulfuric acid solution that has a higher sulfuric acid concentration than said first sulfuric acid solution from outside into said sulfuric acid electrolytic cell, wherein said first electrolytic sulfuric acid containing said first sulfuric acid solution and oxidizing agent, and said second sulfuric acid solution, are mixed; and performing electrolysis to form a cleaning solution comprising said first electrolytic sulfuric acid and a second electrolytic sulfuric acid, containing the first sulfuric acid solution, the second sulfuric acid solution, and oxidizing agent, in said sulfuric acid electrolytic cell; and as a third step, supplying said cleaning solution to a cleaning tank to perform cleaning treatment of an object to be cleaned.