The present disclosure provides a lithography apparatus. The lithography apparatus includes a radiation source providing a radiation energy with a wavelength selected from the group consisting of 193 nm, 248 nm, and 365 nm; a lens system configured approximate to the radiation source; a mask chamber proximate to the lens system, configured to hold a mask and operable to provide a single atom gas to the mask chamber; and a substrate stage configured to hold a substrate and receive the radiation energy through the lens system and the mask during an exposing process.