NUMERICAL MODELING OF THE PROCESSES OF EXPOSURE AND DEVELOPMENT IN ELECTRON-BEAM LITHOGRAPHY ON HIGH-TEMPERATURE SUPERCONDUCTOR THIN-FILMS

In the present work, a numerical modelling of the processes of exposur e and development of the resist during electron beam lithography on st ructures incorporating YBa2Cu3O7 high-temperature superconductor thin films is performed. The Monte Carlo method is used to simulate the pen etration of accelerated electrons in the target and to obtain radial d istributions of the absorbed electron energy density in the resist, du ring the irradiation of 125 nm polymethylmethacrylate resist layer/YBa 2Cu3O7 film of thickness d = 0, 100 and 300 nm/SrTiO3 or MgO substrate at beam energies E-0 = 25, 50 and 75 keV. These distributions are app roximated by an analytical function, called 'proximity function', whos e parameters are calculated using an original Monte Carlo technique, a nd are used as input data in the modelling of the process of developme nt of the electron resist. The results show that electron beam lithogr aphy on the above-mentioned targets is associated with an enhanced pro ximity effect in comparison with that on the conventional in microelec tronics targets PMMA/Si substrate or PMMA/SiO/Si substrate, and it has to be taken into account in order to create patterns of intended dime nsions. (C) 1998 Elsevier Science S.A. All rights reserved.