Conformal Electroless Deposition Of Cu Seed Layer On A 60-nm Trench Pattern Modified With A Self-assembled Monolayer

摘要

We have developed a novel activation technique for the conformal electroless deposition (ELD) of Cu on a SiO_2 substrate modified with an organic self-assembled monolayer. The SiO_2 substrate was modified with amine groups using 3-aminopropyltriethoxysilane and Au nanoparticles (AuNPs) to form a uniform, continuous catalyst for ELD. The Au catalytic layer formed on the amine-SiO_2 substrate was stabilized by electrostatic interactions between the positively charged protonated-amine self-assembled monolayer (SAM) and negatively charged AuNPs. Cu films were then electrolessly deposited on Au-catalyzed SiO_2 substrates. The Cu seed layer formed by this method showed a highly conformal and continuous structure. Cu electrodeposition on the 60-nm trench was demonstrated using an acid cupric sulfate electrolyte containing chloride, polyethylene glycol 4000 and bis(3-sulfopropyl)disulfide. The resulting electroplated Cu showed excellent filling capability and no voids or other defects were observed in a 60-nm trench pattern.