Beyond interfacial anion/cation pairing: The role of Cu(I) coordination chemistry in additive-controlled copper plating

Towards Structural Analysis of Polymeric Contaminants in Electrodeposited Cu films

“…The physical origin of these temporal instabilities is a so-called N-shaped negative differential resistance (N-NDR) [39,40] that, within a relatively narrow current range, is manifested by potential oscillations during chronopotentiometric measurements. The plot shows seven regular potential oscillations that are attributed to sequential formation of the stable Imep-Cu(I)-MPS suppressor film and its partial dissolution (deactivation) at the interface [29,30]. The intervals at higher overpotentials comprised between sharp potential steps correspond to an active Imep-Cu(I)-MPS diffusional barrier being operative at the interface.…”

“…The H2O-Cu(I)-MPS complex is a byproduct of the SPS which undergoes adsorptive dissociation on the Cu surface [29,30]. A combination of Cu(I) coordination coupled to inner-salt formation and inter-chain anion/cation pairing has been proven to be the chemical origin of the surfaceconfined precipitation of these suppressor/leveler adducts ( Fig.…”

“…Recent mechanistic studies proposed an adduct of the Imep polymer with H2O-Cu(I)-MPS complexes as the active suppressor ensemble being operative at the interface during Cu plating in the presence of the two-component Imep/SPS additive package [29,30]. The H2O-Cu(I)-MPS complex is a byproduct of the SPS which undergoes adsorptive dissociation on the Cu surface [29,30].…”

“…1). To determine to which extent and under which experimental conditions these species get incorporated into the copper film upon electrodeposition, we make use of a particular nonlinear instability of the Imep/SPS additive system that occurs under specific galvanostatic plating conditions [29,30]. The physical origin of these temporal instabilities is a so-called N-shaped negative differential resistance (N-NDR) [39,40] that, within a relatively narrow current range, is manifested by potential oscillations during chronopotentiometric measurements.…”

“…In this context, such more advanced approaches of leveling are not predominantly based on the classical transportation and inclusion concept but rely on sophisticated synergistic and antagonistic interactions with SPS as recently discussed [29][30][31]. Prototypical additives exhibiting this bifunctionality are polymerizates of epichlorohydrin and imidazole (denoted Imep hereinafter, see Fig.…”