Abstract A one-step aqueous diazonium-based process has been proved efficient with respect to the covalent grafting of aminophenyl layers onto KMPR photoresist polymer. In contact with acidic palladium chloride solution… Click to show full abstract
Abstract A one-step aqueous diazonium-based process has been proved efficient with respect to the covalent grafting of aminophenyl layers onto KMPR photoresist polymer. In contact with acidic palladium chloride solution for only a few minutes, the positively charged protonated aminophenyl groups on the modified KMPR surface can electrostatically immobilize PdCl42− complexes. This KMPR surface functionalized with palladium-aminophenyl complex activators enables initialize the subsequent autocatalytic deposition of nickel (electroless nickel plating) and leads to a formation of adhesive nickel-boron film onto KMPR substrate. Our proposed green chemistry strategy for the metallization of KMPR photoresist polymer via the diazonium reduction suggests an opportunity to benefit from the incomparable physico-chemical properties of KMPR by integrating it within MEMS structures. The obtained 60 nm thick and compact nickel‑boron alloy (93:7 by weight), evidenced through SEM, AFM and XPS techniques, can be used as a conductive seed layer for direct electrolytic deposition of copper. Consequently, a vacuum-free process for copper filling of mechanical features etched inside the KMPR layer has been demonstrated.
               
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