Selective Self-Assembled Monolayer for Copper Surface Protection During Plasma Activation of Hybrid-Bonded Wafers

Self-assembled monolayer (SAM) materials that are selectively deposited on metals have been utilized as a protection layer during the plasma treatment of patterned copper-dielectric wafers. Plasma activation of the dielectric surface encourages dangling bond formation which increases bond strength, however copper oxidation during treatment may impact electrical performance of the bonded interconnect. Bond strength, physical characterization, and electrical tests were conducted to characterize bond performance with and without SAM protection. SAM-protected bonded wafers exhibit improved bond strength and reduced occurrence of harmful copper oxidation and are not found to degrade bond performance relative to unprotected wafer pairs.