(295c) Formulation of Post Cobalt CMP Cleaning Solution Based on Stability Constants of Metal Complexes
AIChE Annual Meeting
2019
2019 AIChE Annual Meeting
Process Development Division
Tools and Techniques for Product Design
Tuesday, November 12, 2019 - 8:50am to 9:15am
In this study, we focus on the formation and the removal of cobalt-benzotriazole (Co-BTA) complexes based on their stability constants. We also discuss how the various components present in the cleaning solution help in the removal of these contaminants from various film surfaces that are used in cobalt interconnects. The stability constant, log Keq, of Co2+-BTA complex was found to lie between 2.7 and 3.9 in the pH range of 6 â¼ 12, much smaller than the Co3+-ethylenediaminetetraacetic acid (EDTA) complex (log Keq = 36.0). The role of potassium persulfate (K2S2O8) and EDTA, that help in the oxidation and ligand exchange of Co2+-BTA complexes, respectively, is also established. Additionally, sodium dodecylbenzenesulfonate (SDBS) was able to suppress both the potential difference (âEcorr) to about 10 mV for the Co/TiN couple, and the corrosion currents of Co film too. Thus, we were able to remove the Co-BTA complexes adsorbed on Co, Titanium Nitride (TiN), Silicon Nitride (SiN), and Silicon dioxide (SiO2) film surfaces, by exposing them to an aqueous solution of 50 mM EDTA, 1.5 wt% K2S2O8, and 1 mM SDBS at pH 12.