“Advancing Molybdenum CMP: Understanding Inhibition Mechanism of Environmentally Friendly Amino Acids via Passivation Layer Analysis”
Seokgyu Ryu
Abstract
Molybdenum (Mo) is increasingly recognized in the semiconductor industry for its superior conductivity, mechanical properties, and chemical stability, which positions Mo as a viable alternative to copper (Cu) in the Back End of Line (BEOL) process. Chemical Mechanical Planarization (CMP) is crucial for achieving a smooth and uniform surface necessary for device performance. However, due to the extensive oxidation stage of Mo, controlling the corrosion that occurs during the CMP process is challenging, and the self-dissolution characteristics of Mo oxide make uniform surface control difficult. Amino acids, featuring amine groups and carboxyl groups, emerged as promising eco-friendly additives capable of inhibiting corrosion in CMP processes. Here in, this paper aims to investigate the surface response for stabilizing Mo oxidation by adding various amino acids during CMP. In pH 2 environments, amino acids such as arginine, histidine, and methionine, which have electron-donating properties, demonstrate stable corrosion inhibition compared to aspartic acid and glycine, which have electron-withdrawing properties, thereby reducing the material removal rate (MRR) and static etching rates (SER). Electrochemical analysis confirmed that guanidine, imidazole, and thioether, which are strong electron-donating functional groups (arginine, histidine and methionine), form a passivation layer on the Mo and Mo oxide surface increasing resistance and effectively inhibiting corrosion. Density Functional Theory (DFT) simulations demonstrate that higher binding energy between Mo oxide and amino acids correlates with improved corrosion inhibition. In particular, the thioether functional group of methionine exhibits low SER and high MRR due to its selective binding energy with the Mo oxide surface. Furthermore, the S functional group of the amino acid acts as a promising additive that maintains reactivity in acidic conditions owing to the zwitterionic characteristic of the amino group, while simultaneously ensuring corrosion inhibition and an acceptable level of material removal rate due to an adequate presence of lone pair electrons.
Monday, 11/11/2024 at 4:30 pm
CAMP 176
Short bio
Dr. Seokgyu Ryu got his Ph.D. in Energy Engineering, studying lithium secondary batteries, at Kyung-pook National University in South Korea in 2023. He subsequently became a part of Clarkson University, where he has been deeply involved in research and development related to Chemical Mechanical Planarization (CMP). He focuses in post-metal processing, advanced computational simulations for next generation metal and oxide, innovative slurry formulation, non-contact post-CMP cleaning techniques, and in-situ electrochemistry (tribo-corrosion) as a primary focus. He focuses on post-metal oxidation mechanisms in the CMP process, which helps deepen the understanding of surface chemistry and improves semiconductor manufacturing techniques.