Numerical modelling 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 exposure and development of the resist during electron beam lithography (EBL) on structures incorporating YBa2Cu3O7 high temperature superconductor (HTS) thin films is performed. Monte Carlo method is used to simulate the penetration of accelerated electrons in the target and to obtain radial distributions of absorbed electron energy density in the resist, during the irradiation of structures: 125nm polymethylmethacrylate (PMMA) resist layer (PMMA is the most widely used electron resist)/YBa2Cu3O7 film of thickness d=0, 100 or 300nm (YBa2Cu3O7 is the most promising HTS material for deposition of thin films)/SrTiO3 or MgO substrate (these are the most often used substrates for YBa2Cu3O7 thin films growth) at beam energies E0=25, 50 or 75keV. These distributions are approximated by a proper analytical function (combination of double Gaussian and exponential functions), called “proximity function”, the parameters of which are calculated using an original Monte Carlo technique and are used as input data in the modelling of the process of development of the electron resist.