Progress in the development of extreme ultraviolet lithography exposure systems

Extreme Ultraviolet Lithography (EUV) is viewed by many as the logical extension of current optical lithography which will enable future generations of integrated circuits (ICs) to be printed with feature sizes of 100nm and below. With the completion of the research phase and demonstration of practical feasibility in 1996, this technology has moved into active development in the United States, Europe and Japan. The development is now focusing on manufacturing system designs for the 100nm generation and below of ICs. The fundamental approach of EUV is to achieve sub 100nm resolution by dramatically reducing the exposure wavelength, dawn to 13nm, and using all reflective, multilayer-coated imaging optics. The light source for these tools can be either a laser produced plasma or a synchrotron. The most common system architecture considered by most groups is one based on a ring field camera and a step and scan mask and wafer stage system, similar to what is used in today's optical scanners for 0.25micron and below. In the U.S. the development is being carried out in a partnership between an industrial consortium, called the EUV LLC (made up of AMD, Intel and Motorola) and a Virtual National Laboratory (made up of Lawrence Berkeley National Laboratory, Lawrence Livermore National Laboratory and Sandia National Laboratories). This paper will describe the essential elements of a practical EUV lithography tool and the performance trades between the various subsystems that are consistent with commercial throughput requirements.