Limits to Ion Beam etching of Mo / Si multilayer coatings

Abstract

Recently ion beam etching of electron beam deposited metal layers on C has resulted in higher x-ray reflection coefficients1. In spite of the widely recognized importance of Mo/Si multilayer coatings for projection lithography, little work has been done to use the etching technique on multilayer mirrors made of this combination of materials. As Mo/Si multilayer mirrors of d-values greater than 12 nm. have already been made with reflectivities very close to the theoretical maximum2, our main interest is in multilayers with smaller d-values.