Calculation of the optimum electron energy of a dedicated storage ring for X-ray lithography

Depending on the electron energy of a storage ring, exposure time and contrast due to the mask absorber are calculated. Different combinations of beam-line windows, mask membranes, and thicknesses of absorber assuming the use of PMMA resist are taken into account. The influence of electrons produced in the substrate and backscattered into the resist is also numerically estimated. From these evaluations it is concluded that the optimum electron energy of a storage ring for X-ray lithography is 0.9 GeV at a magnetic field of 1.5 T in the deflection magnets.