Surface cleaning effects on reliability for devices with ultrathin oxides or oxynitrides

Kafai Lai; Ming-Yin Hao; Wei-Ming Chen; Jack C. Lee

doi:10.1117/12.186742

14 September 1994 Surface cleaning effects on reliability for devices with ultrathin oxides or oxynitrides

Kafai Lai, Ming-Yin Hao, Wei-Ming Chen, Jack C. Lee

Proceedings Volume 2334, Microelectronics Manufacturability, Yield, and Reliability; (1994) https://doi.org/10.1117/12.186742
Event: Microelectronic Manufacturing, 1994, Austin, TX, United States

Abstract

A new wafer cleaning procedure has been developed for ultra-thin thermal oxidation process (<EQ 50 angstrom). This involves a modified RCA clean and a two-step dip, first in diluted HF and then in a methanol/HF solution, with no final DI water rinse. Ultrathin thermal oxides (48 angstrom) and oxynitrides grown in N₂O (42 angstrom) were prepared using this new cleaning and other commonly used cleaning methods to investigate the effects of surface preparation on dielectric integrity. It has been found that this two-dip method produces dielectrics with reduced leakage current and stress-induced leakage current, which are believed to be the critical parameters for ultrathin oxides. Furthermore, this new cleaning procedure improves both intrinsic and defect-related breakdown as well as the uniformity of the current- voltage characteristics across a 4-inch wafer. The methanol/HF dip time has also been optimized. The improvement is believed to be due to enhanced silicon surface passivation by hydrogen, the reduced surface micro-roughness and the absence of native oxide.

Citation Download Citation

Kafai Lai, Ming-Yin Hao, Wei-Ming Chen, and Jack C. Lee "Surface cleaning effects on reliability for devices with ultrathin oxides or oxynitrides", Proc. SPIE 2334, Microelectronics Manufacturability, Yield, and Reliability, (14 September 1994); https://doi.org/10.1117/12.186742

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