Helium ion beam enhanced local etching of silicon nitride

We investigated the effect of the helium ion implantation on the etching rate of silicon nitride in hydrofluoric acid. Helium ions were implanted into 500-nm-thick silicon nitride film with energies from 15 keV to 35 keV. The ion fluence from 10¹⁴ cm⁻² to 10¹⁷ cm⁻² was used. All samples were investigated with a scanning electron microscope and atomic force microscope. The dependence of the etching rate on the concentration of ion-induced defects is obtained.