The study of the line grating resist profile in PMMA bilayer on SiO₂/Si substrate at 20 keV electron energy

Abstract We present experiments and simulations of the electron lithography process aimed at optimizing parameters for the lift-off technique, a critical step in creating metal patterns on a substrate using an electron beam. The study focused on a bilayer consisting of two PMMA resists with different molecular weights - 950,000 on the top and 495,000 on the bottom - corresponding to different sensitivities. The shape of the developed resist images, specifically in the case of a line grating (Line/Space 100/500 nm), was examined. The influence of the exposure dose on the sidewall geometry of the developed profiles in a 550 nm bilayer PMMA resist system was investigated both experimentally and theoretically to achieve nearly vertical profile sidewalls. Contour plots showing the half linewidths of the developed bilayer PMMA resist as a function of the exposure dose along the resist depth were obtained through simulation, allowing for the prediction of profile geometry for doses ranging from 440 μC/cm 2 to 760 μC/cm 2 .