The Radical Transport in the Narrow-Gap-Reactive-Ion Etcher in SF₆ by the Relaxation Continuum Model

We have established a selfconsistent modeling of a narrow-gap reactive ion etcher (N-gap-RIE) with parallel-plate geometry in SF₆. Using the discharge structure of the relaxation continuum model, we have numerically predicted the radical transport to the surface of N-gap-RIE in SF₆ under two different surface reactions. The spatiotemporal profiles of radicals and neutrals are demonstrated for a long time scale (0–1 s) at between 0.05 Torr and 1.0 Torr at 13.56 MHz. The estimated etch rate of Si wafer with F radicals agrees reasonably well with the previous experimental value obtained under a low-power condition. It is stressed from the present result that the ion-molecule reactions for the generation of F radicals as well as the electron impact dissociation of SF₆ are of great importance.