Study of Removal Process for Buffer Layer on Multilayer of EUVL Mask

摘要

To obtain a stable pattern profile for the SiO_2 buffer layer of an EUVL (Extreme Ultraviolet Lithography) mask, the process latitude available under actual manufacturing conditions was examined by using a conventional spin wet etcher and trying to make the etching depth as uniform as possible. Generally, wet etching uniformity depends on the sequence of the paddling and swing of the etchant nozzle. A uniformity of 1.5%, which meets manufacturing requirements, was found to be obtainable with a special nozzle. This report details a process scheme for removing the buffer layer on the multilayer of an EUVL mask, and presents a method of inspecting the buffer layer along with some simulation results on the printability of residues near the pattern edge.