Si is very reactive to normal plasma etchants such as fluorine based chemicals and the reactions are inherently isotropic. To fabricate small and/or high aspect ratio nanoscale structures in Si, anisotropic profile 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 mix Ar with F etching gases directly, an alternating Ar and F gas flow process was proposed. It is interesting to see that the Si etching profile, etching rate and etching selectivity are all improved by alternating Ar bombardment and SF6/C4F8 etching steps. The Si etching rate is determined by the Ar treatment step in alternating Ar and F two step process.
Citation: Microelectronic Engineering
Pub Type: Journals
Plasma, Etching, Silicon