Structures of Cu surfaces developing in benzotriazole solutions: Effect of pH

Abstract

The effect of pH on layer formation onto clean Cu surfaces in benzotriazole (BTA) aqueous solutions was studied by in situ spectroscopic ellipsometry. The effect of H2O2 addition was also investigated. Time changes in the ellipsometric parameters Ψ and Δ, which correspond to the structural changes of the layers on Cu, were discussed. In acidic solutions, a BTA or a Cu–BTA complex layer grows directly on Cu. The out-diffusion of Cu is suppressed at the Cu layer interface. When H2O2 was mixed, the Cu surface is eroded in acidic solutions. In alkaline solutions, the BTA layer grows on the oxidized Cu layer, or no growth occurs, depending on the composition of the solutions. In neutral solutions, the Cu–BTA complex layer forms on Cu, and the uncovered part is oxidized in the presence of H2O2.

Thin layer growth on cobalt surface in solutions simulating slurry chemistry for chemical mechanical polishing

“…20) In order to determine the physicochemical nature of the layer, we employed Ψ-Δ trajectory analysis. 19,20,23) In this analysis, the experimental sets of Ψ and Δ at 633 nm are plotted and are compared with those calculated for various thicknesses and complex refractive indices. Before doing this, the refractive index of our clean cobalt surface must be determined; this was carried out using the Ψ and Δ at 408 s ("before solution supply") and the determined value at 633 nm was 2.53 + 4.31i which was in a proper agreement with a reported value.…”

“…We have studied the growth of a passivation layer on Cu in aqueous solutions of a corrosion inhibitor and an oxidizer using spectroscopic ellipsometry, [18][19][20] where benzotriazole (C 6 H 4 N 3 H, CAS 95-14-7) was used as a corrosion inhibitor and hydrogen peroxide was used as an oxidizer. Ellipsometry is a powerful tool to enable fast and real-time measurements of films on a specimen surface in a liquid and allows us to determine the physical structures and properties of the film.…”

Growth kinetics of Cu surface layers in H2O2–BTA aqueous solutions

“…The profiles of the three spectra here are almost identical; the spectra shifted upwards or downwards when treated with the solutions. Therefore, we can focus only on the changes of Δ at a particular wavelength to discuss the decrease or increase of the film thickness, as noted in our previous studies, 22,23) and as discussed later. According to the tradition in ellipsometry, 25,26) 633 nm was selected as a representative wavelength, as in our previous work.…”

“…Ψ−Δ trajectory analysis, which plots the time changes of a set of (Ψ, Δ), is very useful to understand the surface behavior. [22][23][24]26) Figure 4 shows the Ψ−Δ trajectory in this run. The straight lines in Fig.…”

“…10 nm) that functions as a protective (passivation) layer is formed. 22,23) In our previous studies data acquisition was started 30 s after immersion of the specimen in an optical cell (ca. 20 ml) to allow for stabilization of the liquid fluctuation.…”