The significance of reactive ions and reactive neutrals in ion-beam-assisted etching

Using a custom designed beam analyzer system, the ionic species from a broad beam ion source have been measured under various etching conditions. In broad beam ion-beam-assisted etching (IBAE), it was observed that up to 25% of the ionic species are from the reactive neutral component backdiffusing into the ion source through the extraction grids depending on the ambient conditions. With the use of the constructed beam analyzer, known ionic species were also used for reactive sputtering and IBAE. The ionic species from Ar, Kr, Xe, Cl2, and CCl4 gases were directed at a Si substrate at 1 keV both with and without the presence of a chemically reactive neutral component of Cl2. In reactive sputtering, the etch yields were primarily dependent on the reactivity of the ionic species. However, in IBAE the etching mechanisms are more dramatically affected by the reactive neutral component on the surface than by the ion beam. That is, the etching component of the ion beam in IBAE is dominated more by its mass and acceleration voltage than by the reactivity of the species.