Ultrahigh selective etching of Si3N4 over SiO2 using plasma-less dry process for 3D-NAND device applications

Chih-Yu Hsu; Peng Shen; Nathan Stafford

doi:10.1117/12.2504426

20 March 2019 Ultrahigh selective etching of Si3N4 over SiO₂ using plasma-less dry process for 3D-NAND device applications

Chih-Yu Hsu, Peng Shen, Nathan Stafford

Author Affiliations +

Proceedings Volume 10963, Advanced Etch Technology for Nanopatterning VIII; 109630M (2019) https://doi.org/10.1117/12.2504426
Event: SPIE Advanced Lithography, 2019, San Jose, California, United States

Abstract

This study provides a new chemistry composition as an effective etchant with a plasma-less dry process for selectively etching Si₃N₄ to SiO₂ with selectivity over 200. Both blanket and patterned wafers were examined. To investigate the parameters affecting selectivity, blanket wafers were tested. Etch rate and selectivity can be optimized by tuning the etchant concentration, chamber temperature and chamber pressure. The selectivity can be tuned from 10 to over 200 depending on the testing condition. It was found nearly etch stop of SiO₂ with increasing the etching time, leading to higher selectivity with increasing the processing time. Under the optimized condition, etching rates of Si₃N₄ > 30 nm/min and SiO₂< 0.2 nm/min were obtained. It was also demonstrated on 3D-NAND patterned wafers of ONON stacked layer with pre-etched holes. The Si₃N₄ layers can be removed with lateral etching rate >20 nm/min, while maintaining the SiO₂ layer.

Citation Download Citation

Chih-Yu Hsu, Peng Shen, and Nathan Stafford "Ultrahigh selective etching of Si3N4 over SiO₂ using plasma-less dry process for 3D-NAND device applications", Proc. SPIE 10963, Advanced Etch Technology for Nanopatterning VIII, 109630M (20 March 2019); https://doi.org/10.1117/12.2504426

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