Process monitoring of LPCVD silicon nitride and polysilicon by variable-angle spectroscopic ellipsometry

Soon Yoong Loh; Terence Kin Shun Wong; Man Siu Tse; Wang Ling Goh

doi:10.1117/12.404908

20 October 2000 Process monitoring of LPCVD silicon nitride and polysilicon by variable-angle spectroscopic ellipsometry

Soon Yoong Loh, Terence Kin Shun Wong, Man Siu Tse, Wang Ling Goh

Author Affiliations +

Proceedings Volume 4230, Micromachining and Microfabrication; (2000) https://doi.org/10.1117/12.404908
Event: International Symposium on Microelectronics and Assembly, 2000, Singapore, Singapore

Abstract

Variable angle spectroscopic ellipsometry (VASE) has been used to monitor the deposition of silicon nitride (SiN_x) and polycrystalline silicon (poly-Si) by low pressure chemical vapor deposition. SiN_x with different nitrogen content and poly-Si were deposited onto Si wafers with a thin layer of thermal oxide. Ellipsometric data was acquired over the spectral range 270 nm - 1700 nm at multiple angles of incidence. For each material, two optical function models were used for fitting of the ellipsometric spectra. In the case of SiN_x, the Cauchy model and the parametric semiconductor model resulted in fits of comparable quality and the optical functions of SiN_x depend on the flow ratio of the dichlorosilane and ammonia used for the deposition. For poly-Si, the parametric semiconductor model was found to give a better fit than the Bruggeman effective medium approximation. In addition, some of the poly-Si samples were diffusion doped and in-situ doped with phosphorus. Using the same optical function models, it was found that diffusion doping resulted in increased crystallinity of the poly-Si. For the in-situ doped poly-Si, there was little change in the optical functions before and after annealing at 1000 degree(s)C. These results demonstrate that VASE is useful for in-line monitoring of thin film deposition in microelectronic processing.

Citation Download Citation

Soon Yoong Loh, Terence Kin Shun Wong, Man Siu Tse, and Wang Ling Goh "Process monitoring of LPCVD silicon nitride and polysilicon by variable-angle spectroscopic ellipsometry", Proc. SPIE 4230, Micromachining and Microfabrication, (20 October 2000); https://doi.org/10.1117/12.404908

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