Galvanic corrosion inhibition from aspect of bonding orbital theory in Cu/Ru barrier CMP

Abstract

In this report, the galvanic corrosion inhibition between Cu and Ru metal films is studied, based on bonding orbital theory, using pyridinecarboxylic acid groups which show different affinities depending on the electron configuration of each metal resulting from a π-backbonding. The sp2 carbon atoms adjacent to nitrogen in the pyridine ring provide π-acceptor which forms a complex with filled d-orbital of native oxides on Cu and Ru metal film. The difference in the d-orbital electron density of each metal oxide leads to different π-backbonding strength, resulting in dense or sparse adsorption on native metal oxides. The dense adsorption layer is formed on native Cu oxide film due to the full-filled d-orbital electrons, which effectively suppresses anodic reaction in Cu film. On the other hand, only a sparse adsorption layer is formed on native Ru oxide due to its relatively weak affinity between partially filled d-orbital and pyridine groups. The adsorption behaviour is investigated through interfacial interaction analysis and electrochemical interaction evaluation. Based on this finding, the galvanic corrosion behaviour between Cu and Ru during chemical mechanical planarization (CMP) processing has been controlled.

Suppression of Dissolution Rate via Coordination Complex in Tungsten Chemical Mechanical Planarization

“…The higher R 2 value of the Langmuir model compared to that of the Freundlich model indicates that the picolinic acid was homogeneously adsorbed on tungsten oxide [18,19], meaning that the picolinic acid forms a monolayer on the surface of tungsten oxide [18]. Both Lee et al and Ramis et al experimentally demonstrated that the strong Lewis acid sites and Brønsted acid sites on the surface of metal oxide films could be active sites for the adsorption of pyridine functional groups [11,20,21]. From this point of view, the coordinated covalent bonding between the pyridine group of picolinic acid and the acidic sites of tungsten oxide resulted in monolayer adsorption on the surface of tungsten oxide [12,13,20,21].…”

“…In our previous study, the selective adsorption mechanism of pyridine functional groups from the aspect of bonding orbital theory was suggested in copper barrier CMP [11]. Herein, we extended it to the tungsten application using α-picolinic acid as an inhibitor to prevent tungsten dissolution, and its impact on tungsten topography was discussed.…”

Density Functional Theory Studies on New Possible Biobased Gemini Corrosion Inhibitors Derived from Fatty Hydrazide Derivatives

“…21,22 The ring structure's planar (flat) configuration further increases the adsorption on the metal surface and better protects it from corrosion. 23 The global hardness measures molecular stability and reactivity. 17 Hard molecules typically have large band gap energy since the inhibitors' reactive sites could only adsorb strongly on the metal surface when the chemical hardness value is at the lowest.…”

“…On the other hand, the highest electron affinity of TADH (1.79 eV) meant a highly specific binding with the metal surfaces. This is due to the strong interaction between the π-electron of the ring structure, which contributes to more robust protection layers on the metal surface. , The ring structure’s planar (flat) configuration further increases the adsorption on the metal surface and better protects it from corrosion …”

The effect of slurry pH on the chemical mechanical planarization of a carbon-doped Ge2Sb2Te5 phase change material

“…Moreover, the electrochemical impedance spectroscopy (EIS) technique is widely used to investigate the electrochemical behaviour of a slurry in the CMP of Al, 28 Cu, 29,30 Ru 31,32 etc. In this study EIS is used to characterize the interaction between the phase change materials and the slurry.…”