Synchrotron radiation lithography for manufacturing integrated circuits beyond 100 nm

Extreme ultraviolet lithography is a powerful tool for printing features of 0.1 mu m and below; in Japan and the USA there is a growing tendency to view it as the wave of the future. With Schwarzschild optics, replication of a 0.05 mu m pattern has been demonstrated in a 25 mu m square area. With a two-aspherical-mirror system, a 0.15 mu m pattern has been replicated in a ring slit area of 20 mm x 0.4 mm; a combination of this system with illumination optics and synchronized mask and wafer stages has enabled the replication of a 0.15 mu m pattern in an area of 10 mm x 12.5 mm. Furthermore, in the USA, the Sandia National Laboratory has succeeded in fabricating a fully operational NMOS transistor with a gate length of 0.1 mu m. The most challenging problem is the fabrication of mirrors with the required figure error of 0.28 nm. However, owing to advances in measurement technology, mirrors can now be made to a precision that almost satisfies this requirement. Therefore, it is time to move into a rapid development phase in order to obtain a system ready for practical use by the year 2004. In this paper the status of individual technologies is discussed in light of this situation, and future requirements for developing a practical system are considered.