An Environmentally-friendly Polishing Slurry Containing Amino Acids for Advanced Cu Interconnect Applications
Monday, September 4, 2023
Sci. Ctr. 160 at 3:00pm
Abstract
Aliphatic amino acids were investigated as environmentally friendly alternatives to benzotriazole (BTA), currently used as corrosion inhibitors for Cu interconnects with Co liners in the chemical mechanical planarization (CMP) process. The influence of three aliphatic amino acids: methionine, leucine, and glutamic acid on Cu corrosion resistance, galvanic corrosion of Cu in contact with Co, Cu removal rates during polishing, and oxide passivation was assessed. Cu and Co films on silicon wafers were polished with controlled pressure and slurry flow rate. Linear sweep voltammetry with a rotating disk electrode was used to determine the corrosion characteristics. The oxide chemistry was evaluated with XPS. Results indicated that the distinctive functional groups present in the amino acids affect both the corrosion and polishing behavior driven by the presence of different Cu species in the passivating film layer, Cu(0), Cu(Ⅰ), and Cu(Ⅱ). Methionine through its sulfur-containing side chain, demonstrated exceptional inhibition capabilities by stabilizing Cu(Ⅰ) species in contrast to Cu(Ⅱ). The branched hydrocarbon chain in leucine contributed to physisorption on Cu surfaces, and mitigating Cu corrosion, while glutamic acid’s additional carboxylic acid group was not effective in minimizing Cu corrosion. The metal removal rate of Cu and Co was more comparable for methionine and glutamic acid versus leucine. Overall, this study establishes key features governing the use of aliphatic amino acids as potential replacements for BTA.
Hoang Tran is currently a 2nd year Ph.D. candidate who joined the Department of Chemical Engineering at Clarkson University in the spring of 2022 and is being advised by Prof. J. Seo and co-advised by Prof. Podlaha-Murphy. Her primary research area involves the development of environmentally friendly CMP slurries for metals. Prior to joining Clarkson University, she completed her M.S. degree in Chemical Engineering at Yonsei University.