An extreme ultra violet (EUV) lithography method includes receiving an EUV light by a scanner from an EUV light source, the EUV light passing through an intermediate focus disposed in the scanner and at a junction of the EUV light source and the scanner; directing the EUV light by the scanner to a reticle in the scanner; and deflecting nanoparticles from the EUV light source away from the reticle by generating a gas flow using a gas jet disposed entirely in the scanner and proximate to an interface of the scanner and the intermediate focus such that the gas jet does not block the EUV light.