The possibility of making lithographic masks based on As2S3 chalcogenide glass with ultimately small size of resist elements has been investigated. Interference lithography using synchrotron radiation with a wavelength of 13.4 nm, corresponding to extreme ultraviolet light, was used. High-quality masks with elements of 30 nm in size were obtained. In a dynamic light scattering study, resist particles of about 3 nm in size were found in the developer after the development process, which corresponds to the intermediate-range order parameter in the structure of the chalcogenide glass. It is assumed that this grain size determines the ultimate resolution, roughness and unevenness of the edge of the inorganic resist mask.