The Effect of Inhibitor Transport on Leveling in Electrodeposition

Abstract

The electrodeposition of nickel into an angular trench in the presence of coumarin, a widely used inhibitor, is simulated using boundary layer approximations representative of flow parallel and transverse to the groove. Based on the diffusion-adsorption mechanism of leveling action, the dependence of the developing contours on variations in the Langmuir coefficient and inhibitor/metal-ion flux ratio are investigated. Leveling efficiency is shown to be highest for thin, planar boundary layers, and lowest for contour following boundary layers. The model successfully predicts the leveling-off of the inhibitor effect with increasing inhibitor vs. metal-ion flux, and that there is an optimal mass transfer boundary layer thickness, or flux of additive which results in superior leveling performance. Satisfactory agreement is found between the predicted contours, obtained by solving the model equations using the boundary element method, and the experimental leveling efficiencies determined by previous investigators.

Electrochemical and Fill Studies of a Multicomponent Additive Package for Copper Deposition

“…The apparent coverage remains relatively constant in a fairly wide range of potential and nearly independent of the electrode rotation speed. The average value of the surface coverage of PEG is around 97%, which is in good agreement with Kelly and West's results 16 and the CVS measurements ͑Fig. 3͒.…”

“…[12][13][14][15] Nevertheless, superfilling by accelerator alone cannot be explained under the framework of established leveling theories, which require that deposition rate ͑at a constant applied potential͒ in a leveling bath should decrease as the rotation speed of an RDE increases. 11,16,17 Figure 6 demonstrates that the opposite trend is observed. 2.…”

Theoretical studies of displacement deposition of nickel into porous silicon with ultrahigh aspect ratio

“…The leveling mechanism of coumarin, as a typical leveler, was extensively studied [48,49,[55][56][57][58][59]. Coumarin inhibits electrochemical deposition by adsorbing on depositing sites and thus reducing the area available for electrodeposition.…”

Role of Chloride Ions in Suppression of Copper Electrodeposition by Polyethylene Glycol

“…As in previous models of adsorbate incorporation during electrodeposition, 8,18 the incorporation rate in Eq. 1 is proportional to the adsorbate coverage and the deposition current density.…”