Cleaning system and cleaning method

1. A cleaning system comprising:

a sulfuric acid electrolytic portion having an anode, a cathode, a diaphragm which is provided between the anode and the cathode, an anode chamber which is demarcated between the anode and the diaphragm and a cathode chamber which is demarcated between the cathode and the diaphragm, the sulfuric acid electrolytic portion being configured to electrolyze a sulfuric acid solution to generate an oxidizing substance in the anode chamber;

a concentrated sulfuric acid supply portion configured to supply a concentrated sulfuric acid solution to the anode chamber;

a tank storing the oxidizing substance generated by the sulfuric acid electrolytic portion; and

a cleaning treatment portion configured to carry out cleaning treatment of an object to be cleaned using an oxidizing solution comprising the oxidizing substance supplied from the tank,

wherein the cleaning system further comprises a solution circulation portion configured to recirculate the oxidizing solution discharged from the cleaning treatment portion to the sulfuric acid electrolytic portion through a recovery tank and a filter and resupply the oxidizing solution from the sulfuric acid electrolytic portion to the cleaning treatment portion through the tank.

2. The cleaning system according to claim 1 , wherein a concentration of the concentrated sulfuric acid is 90% by mass or more.

3. The cleaning system according to claim 1 , wherein the oxidizing substance is peroxomonosulfuric acid.

4. The cleaning system according to claim 1 , wherein a sulfuric acid solution is supplied to the cathode chamber, and the sulfuric acid solution supplied to the cathode chamber has a lower concentration as compared with a sulfuric acid solution which is supplied to the anode chamber.

5. The cleaning system according to claim 1 , wherein at least the anode selected from the group consisting of the anode and the cathode includes an electroconductive base substance and an electroconductive diamond membrane which is formed on the surface of the electroconductive base substance.

6. The cleaning system according to claim 1 , wherein the concentrated sulfuric acid supply portion includes a tank made of quartz.

7. The cleaning system according to claim 1 , wherein the cleaning treatment portion includes a rotary table on which the object to be cleaned is placed, and a nozzle which discharges the oxidizing solution to the object to be cleaned.

8. The cleaning system according to claim 1 , wherein the diaphragm is a neutral membrane subjected to hydrophilizing treatment or an ion-exchange membrane.

9. The cleaning system according to claim 1 , further comprising an ion-exchanged water supply portion which supplies an ion-exchanged water to the cathode chamber.

10. The cleaning system according to claim 9 , wherein the ion-exchanged water supply portion is provided in the anode chamber.

11. A cleaning method comprising:

electrolyzing a concentrated sulfuric acid solution of 90% by mass or more which is supplied to an anode chamber which is demarcated between an anode facing a cathode interposing a diaphragm therebetween and the diaphragm to generate an oxidizing substance in the anode chamber;

storing the oxidizing substance in a tank;

carrying out cleaning treatment of an object to be cleaned using an oxidizing solution containing the oxidizing substance supplied from the tank;

recirculating the oxidizing solution discharged from the cleaning treatment portion to the sulfuric acid electrolytic portion through a recovery tank and a filter; and

resupplying the oxidizing solution from the sulfuric acid electrolytic portion to the cleaning treatment portion through the tank.

12. The cleaning method according to claim 11 , wherein the oxidizing substance is peroxomonosulfuric acid.

13. The cleaning method according to claim 11 , wherein a sulfuric acid solution is supplied to a cathode chamber being demarcated between the diaphragm and the cathode, and the sulfuric acid solution supplied to a cathode chamber has a lower concentration as compared with a sulfuric acid solution which is supplied to the anode chamber.

14. The cleaning method according to claim 13 , wherein the sulfuric acid solution having the lower concentration includes an ion-exchanged water.

15. The cleaning method according to claim 11 , wherein at least a part of the oxidizing solution supplied from the anode chamber is supplied to the anode chamber.

16. The cleaning method according to claim 11 , wherein at least the anode selected from the group consisting of the anode and the cathode includes an electroconductive base substance and an electroconductive diamond membrane which is formed on the surface of the electroconductive base substance.

17. The cleaning method according to claim 11 , wherein the object to be cleaned is placed on a rotary table, and the oxidizing solution is discharged from a nozzle to the object to be cleaned.

18. The cleaning method according to claim 11 , wherein oxidizing solution is heated by a heater before the oxidizing solution is applied to the object to be cleaned.

19. The cleaning method according to claim 11 , wherein the object to be cleaned is a wafer having a resist mask, and the resist mask is removed by the cleaning treatment.