The flexibility of broad‐beam ion processing when used in conjunction with a chemistry assist technique is demonstrated. In this technique called chemically assisted ion beam etching (CAIBE), a chemically reactive gas is introduced into the sample chamber independent of the ion source which can be operated on inert or reactive gases. This allows for a wide range of independent control of the chemical and ionic fluxes not available in other dry etching techniques. Using a two component gas system of argon and xenon difluoride vapor under various operating conditions, the etched wall profiles of Si were found to be controllable. In the reactive ion beam etching mode of operation, overcut profiles with enhanced etch rates over ion milling rates were produced from Ar+and XeF+xbeams resulting from predominantly physical etching mechanisms. With the introduction of low vapor pressures of XeF2into the sample chamber in conjunction with Ar+ion bombardment, profiles resulted from line‐of‐sight ion assisted etching. Vertical walls were obtained with a collimated ion beam while profiles with directional undercutting resulted under highly divergent beam conditions. By increasing in XeF2vapor pressure, undercut profiles from purely chemical etching were formed. Thus, by varying the partial pressure or the ion source operating conditions during an etch process, profile tailoring was accomplished.