Research On Design And Fabrication Of EUV Source Collector

Extreme ultraviolet(13.5nm) lithography(EUVL) is considered as the mostpromising technology below hp22nm node. In a EUV photoetching machine, thecollector is a indispensable component used for improving light power’s utilizationin order to satisfy the exposure power. Due to the extreme short working wavebands,the collector’s structure is very special, and causes the design, fabracation and manyother subjects of the collector becoming difficult in the optical field.Wolter I collector is the pattern especilly for DPP source as well as LPP sourcewith theadvantages such as high collection efficiency, well far field intensityuniformity and so on. The paper chooses the Wolter I collector as the object to study.Comprehensive reseach are done on the design, simulation, processing, testing andintegration of the Wolter I collector.Firstly, the paper analyzes the grazing incidence mode and the mirrors nestedstructure of the collector, which are different from ordinary optical systems. Thepaper also derives two most important parameters, the collection efficiency andetendue, which are related to the design and performance evaluation.Secondly, the paper calculates the radiation characteristics of Xe-filled Z-pinchdischarge plasma source that the collector designed for. The design specificationsare also demonstrated of the collector by the radiation characteristics and otherrequirements. As the common optical design software such as Zemax, Code V donot support the nested grazing incidence structure, the paper proposes a new designmethod for the first time in the world. In addition, the author writes a3D simulationprogram for the collector, which can significantly reduce the design and simulationcost compared to the third-party software such as Tracepro. The results obtained by3D simulation program have a good agreement with that obtained by Tracepro anddemonstrate the designed collector meets all the requirements.Additionally, the paper introduces the foreign collector fabrication method, themandrel replication method and a suitable finish turning method is proposed forexploratory processing of collector. As for the surface testing, a fast testing methodis developed mainly based on imaging principle testing. A processed collector mirroris tested and the results prove the collector mirror satisfies the design specifications.Finally, the paper investigates the integration tolerances, and gives theintegration tolerances of the processed collector mirror. An integrated platform isalso preliminary designed.