The use of electroless copper seed in electrochemical deposited copper interconnect

Copper (Cu) electroplating (EP) process requires a Cu seed to conduct the current. Conventional physical vapor deposition (PVD) seed suffers from poor step coverage while chemical vapor deposition (CVD) seed is cost-ineffective. We therefore propose the use of electroless (EL) technique as a Cu seed deposition method and demonstrate its integration with conventional Cu EP. The EL seed has excellent step coverage which when combined with the bottom-up fill capability of additives-based EP process, produces void-free fill. The EL seed-EP Cu film stack has good resistivity, roughness and acceptable (111) texture. However, some adhesion issues remain to be solved for this integration scheme. [Copyright &y& Elsevier]