Extension of x-ray lithography to 50 nm with a harder spectrum

To be competitive with the next-generation Lithography technologies, synchr otron-based proximity x-ray lithography (PXRL) must prove to be extendible to produce minimum feature sizes of 70 nm and below. We present here a rela tively simple: and practical method to improve the PXRL system performance for the replication of features down to 50 nm with reasonable process latit ude at large (g approximate to 15 mu) mask-wafer gaps. Contrary to previous conclusions indicating lambda=1 nm as the best operating region, we find t hat a significant improvement can be achieved by a modest decrease in the e ffective wavelength of present PXRL systems, and by the use of non-silicon- based materials in beamline filters and masks. The proposed PXRL system req uires a synchrotron storage ring with slightly higher energy than older rin gs such as Aladdin, but well within the design parameters of the newer gene ration of synchrotrons, and some beamline modifications. In addition, a dia mond mask substrate is also utilized to eliminate the x-ray absorption due to the Si-absorption edge at 1.75 keV. (C) 1999 American Vacuum Society. [S 0734-211X(99)13706-5].