Ultrathin MBE-Grown Semiconductor Layer Masks for Focused Ion Beam Lithography

The application of thin semiconductor layers as etch masks for high vacuum lithography is described. Heteroepitaxial layers of InGaAs or InP as thin as 30A were grown by molecular beam epitaxy and patterned using a submicron focused Ga ion beam at low exposure doses. The ion-exposed thin layer can then be used as a mask for material selective etching.