Sub-30 -nm hybrid lithography (electron beam∕deep ultraviolet) and etch process for fully depleted metal oxide semiconductor transistorsExtreme ultraviolet lithography ͑EUVL͒ using 13.5 nm wavelength light is the leading candidate to succeed 193 nm immersion lithography, enabling semiconductor chips with features smaller than 22 nm. Several major programs worldwide have developed this technology in recent years ͓D. A. Tichenor et al., OSA Proceedings on Soft X-Ray Projection Lithography, edited by A. M. Hawryluk and R. H. shipped the first EUV Alpha Demo tools ͑NA= 0.25 full-field scanners͒ to IMEC in Belgium ͓A. M. Goethals et al., Proc. SPIE 6517, 651709 ͑2007͔͒ and CNSE in Albany ͓O. Wood et al., Proc. SPIE 6517, 6517-041 ͑2007͔͒, USA. Currently the development of preproduction tools with targeted shipment of 2009 is well under way. This paper discusses the most critical items for EUVL development, namely, EUV imaging and EUV sources. Furthermore, it elaborates on the necessary development of masks and resists and, for example, quantifies how resist diffusion length can impact imaging capabilities. Results obtained and lessons learned with the Alpha Demo tools are discussed, as well as potential solutions to some of the remaining challenges. Additionally, this paper explains how EUV can realize high productivity ͑Ͼ100 wafers/ h͒ and high resolutions ͑Ͻ22 nm͒ to continue the cost-effective shrink of semiconductors for several generations.
All six NXE:3100, 0.25 NA EUV exposure systems are in use at customer sites enabling device development and cycles of learning for early production work in all lithographic segments; Logic, DRAM, MPU, and FLASH memory. NXE EUV lithography has demonstrated imaging and overlay performance both at ASML and end-users that supports sub27nm device work. Dedicated chuck overlay performance of <2nm has been shown on all six NXE:3100 systems.The key remaining challenge is productivity, which translates to a cost-effective introduction of EUVL in high-volume manufacturing (HVM). High volume manufacturing of the devices and processes in development is expected to be done with the third generation EUV scanners -the NXE:3300B. The NXE:3300B utilizes an NA of 0.33 and is positioned at a resolution of 22nm which can be extended to 18nm with off-axis illumination. The subsystem performance is improved to support these imaging resolutions and overall productivity enhancements are integrated into the NXE platform consistent with 125 wph. Since EUV reticles currently do not use a pellicle, special attention is given to reticle-addeddefects performance in terms of system design and machine build including maintenance procedures.In this paper we will summarize key lithographic performance of the NXE:3100 and the NXE:3300B, the NXE platform improvements made from learning on NXE:3100 and the Alpha Demo Tool, current status of EUV sources and development for the high-power sources needed for HVM.Finally, the possibilities for EUV roadmap extension will be reviewed.
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