Selete's EUV program: progress and challenges

摘要

Selete launched a development program on EUV lithography and related mask technology in April 2006. The program isbased on the concept of "lithography design and integration." It covers a wide range of areas that require further effort toget EUVL ready for volume production and was formulated on the basis that the issues should be considered from avariety of standpoints, such as acceleration of the development of key lithographic components, verification that EUVLis actually suitable for mass production, the construction of mask infrastructure, and the improvement of EUV-specificreliability and productivity. Two exposure tools have been installed as basic infrastructure: the small-field exposure tool(SFET) and the full-field exposure tool (EUV1). The objectives of the SFET installation are acceleration of thedevelopment of resist materials and processes, optimization of the mask structure and materials, and the evaluation of theexposure tool technology with regard to such things as imaging performance, stability, and the lifetimes of the optics andsource components. The objective of the EUV1 installation is to demonstrate that lithography integration is a viable pathto making EUV lithography a practical production technology. We found that the SFET provides both excellentresolution and high tool activity. This high performance helps us to obtain a clear understanding of the current level ofEUVL performance and enables us to learn many things that can be fed back into the development program in the betastage. A 1st static exposure with the EUV1 resolved 30-nm dense and isolated lines and 30-nm holes. The potentialresolution was found to be as good as 28 nm. Although progress was made regarding EUV resist sensitivity and LWR,further progress is needed. A tool for analyzing out-gassing in EUV resists was found to facilitate the development ofboth resist materials and contamination control measures for exposure tools. A prototype full-field actinic inspectionsystem for mask blanks is now under development and should become operational in the 2Q of 2008. A mask protectionengineering (MPE) tool was used to show that a dual-pod carrier is very effective in protecting a mask from particles.Mask pattern defect inspection technology using a DUV wavelength of 199 nm and defect repair technology based on anFIB for EUV mask fabrication are also being developed. This work was supported in part by NEDO.