Pt Etching Method at Low Temperature Using Electrolyzed Sulfuric Acid Solution

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.