New results in high energy proximity x-ray lithography

We report some new results in the use of high energy radiation in proximity x-ray lithography for the 50 run node. The higher energy of the incoming radiation, 2.6 - 2.7 KeV, has two primary benefits: (1) it reduces the diffraction and allows printing of higher resolution features, and (2) it increases the effective depth of exposure allowing larger gap setting; however, the absorption of these photons creates "hot" electrons, which redistributes the energy in the resist, thus creating a uniform 'blur' that limits the resolution by reducing contrast. The impact of the energy redistribution needs to be investigated when increasing the energy of the radiation, and in considering the materials used in both the optics and the mask and resist combination.