Substrate effect in electron beam lithography

Abstract

Electron Beam Lithography (EBL) process strongly depends on the type of the applied lithographic system, composed of electron sensitive polymers and the substrate. Moreover, applied acceleration voltage changes the volume of Backscattered Electrons (BSE) participation in total energy absorption in resist layers. Proper estimation of energy distribution in used materials, due to electron scattering, is the key in final resist profile calculation and critical parameter in the designing process of the lithography exposure. In the presented paper, the Monte Carlo (MC) simulations of electron beam influence on lithographic system, consisting of positive tone resists (PMMA/MA and CSAR-62) spin coated on different substrates, will be presented. For high accuracy, obtained point spread functions were modelled by double-Gaussian function for Si, GaAs, AlGaN/GaN and InP substrates, respectively. Extracted scattering parameters of forward and backward electrons will be shown and their differences will be discussed. Results of simulated and conducted process of 100 nm metallic path fabrication on mentioned materials will be presented and compared. The practical usage of EBL technique will be shown in the aspect off low resolution application in low energy range of primary electron beam.