Conformal electroless filling of Cu into patterned amorphous carbon layer modified by oxygen plasma and aminosilane treatments

In this work, conformal electroless filling of Cu into the patterned chemical vapor-deposited amorphous carbon layer (ACL) pattern was investigated. Due to the difficulty in getting Pd to adsorb onto a pristine ACL, (3-aminopropyl)-trimethoxysilane (APTMS) solution was applied to the surface of the O₂ plasma-treated ACL pattern. The increase in the surface energy and the formation of carboxyl functional groups, induced by O₂ inductively coupled plasma treatments, on the ACL surface were very effective in enhancing the adsorption of APTMS molecules because of a greater number of sp³ bonds on the surface. The modified ACL surface with adsorbed APTMS was successfully activated using the Pd/Sn activation solution and then electrolessly plated with Cu. The results confirmed that conformal electroless filling effectively filled Cu into the patterned ACL trenches.