Rotating compensator spectroscopic ellipsometry (RCSE) and its application to high-k dielectric film HfO2

JingMin Leng; Shifang Li; Jon L. Opsal; David E. Aspnes; Byoung Hun Lee; Jack C. Lee

doi:10.1117/12.405823

2 November 2000 Rotating compensator spectroscopic ellipsometry (RCSE) and its application to high-k dielectric film HfO₂

JingMin Leng, Shifang Li, Jon L. Opsal, David E. Aspnes, Byoung Hun Lee, Jack C. Lee

Author Affiliations +

Proceedings Volume 4099, Optical Metrology Roadmap for the Semiconductor, Optical, and Data Storage Industries; (2000) https://doi.org/10.1117/12.405823
Event: International Symposium on Optical Science and Technology, 2000, San Diego, CA, United States

Abstract

High-k gate dielectric films with equivalent oxide thickness (EOT) of 3 nm or less are becoming the main theme of research and development in ultra-large-scale integrated circuits industry with device dimensions scaled down to less than 130 nm. Among the high-k gate dielectric materials hafnium dioxide (HfO₂) is very promising with its high dielectric constant (approximately 30) and stability in contact with Si. The samples were prepared with a DC magnetron-reactive sputtering method and subsequently annealed in the furnace with a temperature range of 500- 850 degree(s)C. The thickness of the HfO₂ varied from 3.5- 18nm with a hafnium silicate interface layer of approximately 1 nm. The electrical measurement showed that the breakdown voltage is inversely proportional to the physical thickness, suggesting the breakdown process occur at the HfO₂ thin film rather than in the interface layer. To measure the physical thickness of hafnium dioxide and hafnium silicate interface simultaneously, a research grade bench top rotating compensator spectroscopic ellipsometry (RCSE) in the wavelength range of 195-915 nm was used. The dispersion of HfO₂ film was characterized with a two-peak critical point (CP) model and the dispersion of the interface layer of hafnium silicate was characterized with a five-peak CP model. An interface layer thickness of 0.7-2 nm was found for all hafnium dioxide films on Si, depending on the process conditions such as annealing temperature and oxygen flow rate. The same wafers measured by RCSE were later studied by transmission electron microscopy (TEM). The thickness of hafnium dioxide and hafnium silicate determined by TEM is in good agreement with the noninvasive RCSE method.

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JingMin Leng, Shifang Li, Jon L. Opsal, David E. Aspnes, Byoung Hun Lee, and Jack C. Lee "Rotating compensator spectroscopic ellipsometry (RCSE) and its application to high-k dielectric film HfO₂", Proc. SPIE 4099, Optical Metrology Roadmap for the Semiconductor, Optical, and Data Storage Industries, (2 November 2000); https://doi.org/10.1117/12.405823

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