Experimental research on airflow efficiency of dynamic gas lock for extreme ultraviolet lithography

Dynamic gas lock (DGL) is one of the central components of contamination control for extreme ultraviolet lithography, and airflow efficiency is a key parameter. In this paper, the principle of the DGL and airflow efficiency is described at first, then a set of experiments is carried out on a self-developed DGL experimental device. The results of the experiment show that the pressures of the project optics box and the wafer chamber do not influence the airflow efficiency of DGL. In addition, the airflow efficiency increases slowly with the total airflow, and the gradient gradually diminishes. With an increase in the total airflow from 1 to 3 Pa m3/s, the argon efficiency increases from 0.247 to 0.260, while the nitrogen efficiency increases from 0.251 to 0.264, which shows that the efficiency of argon is slightly smaller than that of nitrogen under the same conditions. Within the interesting range of argon gas flow, the maximum difference between theory and experiment is less than 6%, which is acceptable in engineering. The theoretical calculation method in this paper can be used to evaluate the airflow efficiency for engineering applications. It is concluded that the airflow efficiency of the DGL is almost independent of the pressures of the upper and lower sides. However, the total airflow and the gas species will change the airflow efficiency.