Layer-forming method, optical element and optical system

Abstract

A method of forming a layer (3) on a substrate (2) made of a fluoridic material includes: depositing a coating material (9) on the substrate to form the layer and generating a plasma (12) to assist the deposition of the coating material. The plasma is formed from a gas mixture (14) containing a first gas (G) and a second gas (H), wherein the second gas has an ionization energy less than an ionization energy of the first gas, the first gas is a noble gas and the second gas is a further noble gas. An associated optical element includes: a substrate (2) composed of a fluoridic material, in particular a metal fluoride, wherein the substrate has a coating (18) having a layer (3) formed by the above method. An associated optical system, in particular for the DUV wavelength range, includes at least one such optical element.

Dependencies are inferred from the claim text.