Investigations with broad‐beam argon and reactive fluorinated ion beams have shown that the etched wall profiles of silicon at submicrometer linewidths can be controlled by varying the ion energy, current, and partial pressure of XeF2. Inert argon and reactive ion beams generated from xenon difluoride produced overcut profiles resulting from predominantly physical etching mechanisms. With very low partial pressures of XeF2in the background ambient, purely chemical etching of silicon is low while enhanced line‐on‐sight ion‐assisted etching can be used to produce vertical profiles. By increasing the background partial pressure of XeF2, undercut profiles were produced by purely chemical and chemically assisted ion beam mechanisms. Thus, various wall profiles were produced in silicon within the same broad‐beam ion etching equipment using the same two‐component gas system of Ar and XeF2.