Simulational studies of energy deposition and secondary processes in deep x-ray lithography

The effect of secondary radiative processes on the energy deposition patterns in x-ray deep lithography (the first step in the LiGA processes) is investigated via computer simulations. Fluorescence photon and photo- and Auger-electron production in the mask membrane, absorber, resist and substrate are simulated via classical trajectory, Monte Carte techniques. Comparisons of the simulated dose distribution with and without secondary radiative processes show that these processes lead to significant delocalization of the deposited energy, which in turn degrades the developed structure. In addition, an upper limit on the energy spreading effect of higher-order processes is determined. From the calculations presented here, it is clear that the main limiting factor in obtaining a more precise prediction of microstructure shapes is an understanding of the chemical processes in the development step of the LiGA processes.