Microelectronic Engineering

Volume 88, Issue 8, August 2011, Pages 2470-2473

Effect of alternating Ar and SF6/C4F8 gas flow in Si nano-structure plasma etching

https://doi.org/10.1016/j.mee.2010.12.082Get rights and content


Si is very reactive to normal plasma etchants such as fluorine (F) based chemicals and the reactions are inherently isotropic. To fabricate small and/or high aspect ratio nanoscale structures in Si, an anisotropic etching process is necessary. SF6 combined with C4F8 has been demonstrated as a good gas combination for anisotropic Si etching. In this study, Ar gas was introduced into the etching chamber to improve Si etching rate. In addition to mixing Ar with F etching gases directly, an alternating Ar and F gas flow process is proposed. It is interesting to see that not only Si etching rate but also etching selectivity are improved by alternating Ar bombardment and SF6/C4F8 etching steps. The Si etching rate is determined by the Ar treatment step in this new alternating Ar and F two step process.



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