Instead of using conventional SPM cleaning, where peroxide produces Caro's acid taking the main part in the oxidation process, electrolytic Sulfuric Acid is introduced. Electrolytic sulfuric acid produces Persulfate ion, which is more powerful oxidizer compared to peroxide used in conventional SPM cleaning. We used the Kurita's “Green Sulfaceed KD”(GS-KD) Module to supply the electrolytic sulfuric acid into the DNS batch type FC-3100 system.
Electrolytic Sulfuric Acid, compared to conventional SPM Cleaning, showed improvement in the metal, organic removal selectivity. In this paper, cases of process integration challenges concerning the metal, organic removal selectivity are reviewed. In case of a metal residue removal process with metal disclosure, minimum removal is required, however excess metal removal results in contact disconnection. In case of a implant dosed photo resist residue stripping process with danger of metal disclosure, low peroxide SPM cleaning is required however it is insufficient to strip the photo resist residue. Using the Electrolytic Sulfuric Acid, it was possible to meet the requirements of the processes, removing the unneeded residues while maintaning the metal underlayers. The improvement in the removal selectivity became the key factor in overcoming the technical challenges in the processes.