Papers by Author: Hiroshi Morita

Abstract: Recently, in the semiconductor manufacturing industry, NiPt silicide with high conductivity is adopted. However, when removing the NiPt residues in NiPt silicide processing, there is a possibility to damage other metals and silicide. Removal of residual substances must be done with special care. As a conventional method, processing by SPM has been reported by Chur [1]. However, when Pt content is 10% or more, in this method, the wafers must be processed at 150°C for a long period of time. Then, this method may damage a metal gate and silicide. As another method, aqua regia can be used. However, in this method, it takes long time to dissolve NiPt. This paper reports, newly develped Pt etching method using one-step processing of ESA (Electrolyzed Sulfuric Acid) and HCl, and two-step processing using ESA and HCl mixture after HNO₃ and H₂O₂ mixture. This method can treat NiPt silicide at lower temperature within a shorter time than in conventional methods.

Abstract: It is known that resist removal capability of SPM gradually deteriorates during the stripping process. The deterioration is theoretically explained to be the decrease in the concentration of sulfuric acid. On the contrary, in the case of electrolyzed sulfuric acid method, both concentrations of sulfuric acid and of peroxodisulfuric acid produced by electrolysis are kept constant, so that the resist removal capability is maintained for a long term even without addition of hydrogen peroxide. It is proved that resist patterned on φ300mm wafers and implanted at 1E14 atoms/cm² can be removed using electrolyzed sulfuric acid solution without ashing process.