Roughness and light scattering of ion-beam-sputtered fluoride coatings for193 nm

Scattering characteristics of multilayer fluoride coatings for 193 nn depos ited by ion beam sputtering and the related interfacial roughnesses are inv estigated. Quarter- and half-wave stacks of MgF2 and LaF3 with increasing t hickness are deposited onto CaF2 and fused silica and are systematically ch aracterized. Roughness measurements carried out by atomic force microscopy reveal the evolution of the power spectral densities of the interfaces with coating thickness. Backward-scattering measurements are presented, and the results are compared with theoretical predictions that use different model s for the statistical correlation of interfacial roughnesses. (C) 2000 Opti cal Society of America OCIS codes: 310.6860, 290.5820, 180.5810, 140.7240.