Direct seed electroplating of copper on ruthenium liners

The ruthenium (Ru) liner based metallization scheme depends on the ability to electrodeposit Cu onto thin, resistive Ru substrates with substantially high Cu nuclei density. In the present paper, a novel electrochemical bath that utilizes Cu-complexing agents to improve the nucleation of plated Cu films on Ru is presented. Such chemistries can generate Cu nucleation density on Ru greater than 10
¹²
nuclei/cm
²
, thereby enabling robust gap-fill in aggressive (CD~30 nm) dual damascene structures. Complexed-Cu plating chemistries thus provide great potential for extending Cu metallization to future technology nodes.