The use of atomic hydrogen to clean carbon contaminants on multilayers in extreme ultraviolet lithography systems has been extensively investigated. Additional knowledge of the cleaning rate would not only provide a better understanding of the reaction mechanism but would also inform the industry's cleaning process. In this paper, which focuses on the atomic-hydrogen-based carbon contamination cleaning process, a possible mechanism for the associated reactions is studied and a cleaning model is established. The calculated results are in good agreement with the existing experimental data in the literature. The influences of the main factors such as activation energy and types of contamination - on the cleaning rate are addressed by the model. The model shows that the cleaning rate depends on the type of carbon contamination. The rate for a polymer-like carbon layer is higher than the rate for graphitic and diamond-like carbon layers. At 340 K, the rate for a polymer-like carbon layer is 10 times higher than for graphitic carbon layers. This model could be used effectively to predict and evaluate the cleaning rates for various carbon contamination types. (C) 2016 Elsevier B.V. All rights reserved.