Carbon contamination of EUV mask: film characterization, impact on lithographic performance, and cleaning

Abstract

The deposition characteristics of carbon film on EUV mask surface, the impact of carbon deposition on lithography performance, and cleaning of deposited carbon film on EUV mask are studied. The density of the carbon film was found to be nearly half of that of graphite by X-ray reflectivity measurement. The impact of carbon deposition on the lithography performance was simulated by SOLID-EUV. The CD variation by carbon deposition on the mask depends on the deposition profile on the absorber pattern. Intentionally created contaminated masks were treated by a cleaning process using atomic hydrogen. The cleaning efficiency and durability of film materials are discussed.