Optimum energy for high resolution low voltage electron beam lithography -Monte Carlo simulations and experiments

The electron backscattering coefficients of thin tri-level-process layer sy stems in the energy range from 2.5 to 40.0 keV have been calculated by Mont e Carlo simulations. The results show a significant variation of the backsc attering with the primary electron energy and the atomic number of the mate rials used in the layer systems. A local backscattering minimum in the regi on of 4-5 keV has been found for the investigated multilayer systems. Its s tability to variations of the layers' parameters has been investigated. Fir st high resolution experiments at 5.0 keV primary electron energy were carr ied out to determine the minimal achievable grating period with line-to-spa ce ratio of 1:1. Using ZEP-7000 and hexaacetate p-methylcalix[6]arene resis t gratings with 60 and 50 nm minimum period, respectively, were manufacture d.