Optical arrangement for EUV lithography and method for determining a nominal value of a target plasma parameter

摘要

The disclosure relates to an optical arrangement (1) for EUV lithography, comprising: an EUV radiation source (2) for generating EUV radiation (5) at an operating wavelength (AB) in the EUV wavelength range, at least one Vacuum housing (27), in which at least one optical element (12) is arranged and which contains a residual gas, wherein during operation of the optical arrangement (1) a plasma is created in the vacuum housing (5) by an interaction of the EUV radiation (5) with the residual gas. 27) is generated. The optical arrangement (1) comprises an excitation device (30) which is designed to radiate excitation radiation (31) into the vacuum housing (27) at at least one excitation wavelength (λA) which differs from the operating wavelength (AB) as well as a control device (34) which is designed to control the excitation device (30) in order to specifically excite at least one photo-induced reaction in the residual gas in the vacuum housing (27). The disclosure also relates to a method for determining a desired value for a target plasma parameter.