Abstract
We report highly selective etching rates between a Ni‐Cr mask and 
and 
layers as well as highly anisotropic profiles in these materials at a nanometer scale using the Ni‐Cr mask and chemical assisted ion beam etching. The etching rates of Ni‐Cr, 
, and 
depend on 
gas flux, ion beam energy, and ion beam current density. Selectivities of the order of 40:1 and 8:1 between 
, respectively, 
and 
, were obtained at an ion beam energy of 500 eV, beam current density of 0.2 mA/cm2, and a 
flow of 4.2 ml/min.