Fabrication of 100 nm polarization gratings using EBL

We present an approach to fabricate 100 nm polarization gratings on the substrates of Si and quartz slide covered with an aluminum film in a 30 kV acceleration voltage electron beam lithography system. The exposure dose was set from 300 to 1500 μc/cm2, with the other parameters fixed including the electron accelerating voltage, beam spot size and beam current. It is found that when the substrate density changes, the exact exposure doses will be different for the fabrication of 100 nm gratings due to the proximity effect caused by backscattered electrons. According to the theoretical analysis and experimental research, the backscattered area of electrons will be expanded with the increase of the substrate density. Thus, the exposure dose should be properly selected to alleviate the proximity effect caused by the increased density. This work provides a way for the fabrication of 100 nm polarization gratings using EBL.