Effect of Citric Acid in Cu Chemical Mechanical Planarization Slurry on Frictional Characteristics and Step Height Reduction of Cu Pattern
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Copper chemical mechanical planarization (CMP) has become a key process in integrated circuit (IC) technology. The results of copper CMP depend not only on the mechanical abrasion, but also on the slurry chemistry. The slurry used for Cu CMP is known to have greater chemical reactivity than mechanical material removal. The Cu CMP slurry is composed of abrasive particles, an oxidizing agent, a complexing agent, and a corrosion inhibitor. Citric acid can be used as the complexing agent in Cu CMP slurries, and is widely used for post-CMP cleaning. Although many studies have investigated the effect of citric acid on Cu CMP, no studies have yet been conducted on the interfacial friction characteristics and step height reduction in CMP patterns. In this study, the effect of citric acid on the friction characteristics and step height reduction in a copper wafer with varying pattern densities during CMP are investigated. The prepared slurry consists of citric acid (C6H8O7), hydrogen peroxide (H2O2), and colloidal silica. The friction force is found to depend on the concentration of citric acid in the copper CMP slurry. The step heights of the patterns decrease rapidly with decreasing citric acid concentration in the copper CMP slurry. The step height of the copper pattern decreases more slowly in high-density regions than in low-density regions.
Abstract
Copper chemical mechanical planarization (CMP) has become a key process in integrated circuit (IC) technology. The results of copper CMP depend not only on the mechanical abrasion, but also on the slurry chemistry. The slurry used for Cu CMP is known to have greater chemical reactivity than mechanical material removal. The Cu CMP slurry is composed of abrasive particles, an oxidizing agent, a complexing agent, and a corrosion inhibitor. Citric acid can be used as the complexing agent in Cu CMP slurries, and is widely used for post-CMP cleaning. Although many studies have investigated the effect of citric acid on Cu CMP, no studies have yet been conducted on the interfacial friction characteristics and step height reduction in CMP patterns. In this study, the effect of citric acid on the friction characteristics and step height reduction in a copper wafer with varying pattern densities during CMP are investigated. The prepared slurry consists of citric acid (C6H8O7), hydrogen peroxide (H2O2), and colloidal silica. The friction force is found to depend on the concentration of citric acid in the copper CMP slurry. The step heights of the patterns decrease rapidly with decreasing citric acid concentration in the copper CMP slurry. The step height of the copper pattern decreases more slowly in high-density regions than in low-density regions.
참고문헌 (20)
- Chen, K. W., "Novel slurry solution for dishing elimination in copper process beyond 0. 1-µm technology", Thin Solid Film, 498, pp.50~55 (2006)
- DeNardis, D., "Characterization of copper-hydrogen peroxide film growth kinetics", Thin Solid Films, 513(1-2), pp.311~318 (2006)
- Gorantla, V. R. K., "Citric acid as a complexing agent in CMP of copper", J. Electrochem. Soc, 152(5), pp.G404~G404 (2005)
- Seal, S., "Effect of glycine and hydrogen peroxide on chemical-mechanical planarization of copper", Thin Solid Films, 423, pp.243~251 (2003)
- Chen, J. C., "Effect of hygrogen peroxide and alumina on surface characteristics of copper chemical-mechanical polishing in citric acid slurry", Mater. Chem. Phys, 87, pp.387~393 (2004)
- Lin, J. Y., "Adsorption and desorption studies of glycine and benzotriazole during Cu oxidation in chemical mechanical polishing bath", J. Electrochem. Soc, 155(6), pp.H396~H400 (2008)
- Cooper, K., "Simulation of particle adhesion : Implications in chemical mechanical polishing and post chemical mechanical polishing cleaning", J. Electrochem. Soc., 148(11), pp.G662~G667 (2001)
- Liang, H., "Influence of oxides on friction during Cu CMP", J. Electron. Mater., 30(4), pp.391~395 (2001)
- Ishikawa, A., "Influence of slurry chemistry on frictional force in copper chemical mechanical polishing", J. Electrochem. Soc., 152(9), pp.G695~G697 (2005)
- Fu, G., "An analytical dishing and step height reduction model for chemical mechanical planarization(CMP)", IEEE Trans. Semi. Manufac, 16(3), pp.477~487 (2003)
- Gorantla, V. R., "Study of pattern density effects in CMP using fixed abrasive pads", J. Electrochem. Soc, 150(12), pp.G821~G825 (2003)
- Wu, L., "Analytical model for chemical mechanical polishihng of features with different pattern density", J. Electrochem. Soc., 153(7), pp.G669~G676 (2006)
- Nguyen, V., "Dependency of dishing on polish time and slurry chemistry in Cu CMP", Microelectron. Eng, 50, pp.403~410 (2000)
- Lee, H. S., "The characteristics of frictional behavior in CMP using an integrated monitoring system", Key Eng. Mater, 339, pp.152~157 (2007)
- 이현섭, "화학기계적 연마(CMP) 공정에서의 트라이볼로지 연구 동향", 한국트라이볼로지학회지, 34(3), pp.115~122 (2018), 한국트라이볼로지학회[DOI]
- Hernandez, J., "Surface chemistry studies of copper chemical mechanical planarization", J. Electrochem. Soc., 148(7), pp.G38~G397 (2001)
- Thakurta, D. G., "Three-dimensional chemical mechanical planarization slurry flow model based on lubrication theory", J. Electrochem. Soc, 148(4), pp.G207~G214 (2001)
- Ye, N., "Indentation analysis of elastic-plastic homogeneous and layered media : Criteria for determining the real material hardness", J. Tribol., 125(4), pp.685~691 (2003)
- Ihnfeldt, R., "Effect of CMP slurry chemistry on copper nanohardness", J. Electrochem. Soc., 155(6), pp.H412~H420 (2008)
- Zeidler, D., "Influence of process parameters on chemical-mechanical polishing of copper", Microelectron. Eng., 37-38, pp.143~149 (1997)