Is extreme-ultraviolet pellicle possible? - In terms of heat absorption

Abstract

In EUVL, a pellicle is required for protecting the mask from contamination. However, the use of the pellicle at the real applications is very challenging since temperature increase due to EUV light absorption can reduce the transmission of EUV beams and distort a transmitted EUV beam profile. In the previous study, we consider the thermal behaviors of the pellicle considering only the film during EUV lithography based on a simple thermal modeling using the heat transfer equations. However the mesh is also required for supporting the thin film. Here we report the study of thermal behaviors of the pellicle including both the film and the mesh. In the previous studies done by others, there are 3 cases depending on linewidth and pitch and we review all the cases. And we take silicon as the material of thin film and wire-mesh. We will show that the temperature increase of the mesh and its dependence on the structure are much smaller than those of the film. Furthermore the conditions of a mesh structure and a material to reduce adverse thermal effects will be discussed. © 2012 SPIE.