Sub-50 nm high density direct electron beam patterning on insulating substrate

High resolution and high density direct e-beam writing process on a transparent insulating substrate for optical devices and biosensors is developed. In this research, we present successful sub-50 nm high density direct e-beam writing process using metal thin film on top of the resist as the anti-charging layer on glass substrate. To improve the resolution of e-beam patterning, we investigated the tendencies of some e-beam process parameters such as dose, beam current, shot pitch, writing method and development time as well on the glass substrate. The charging and backscattering effects were also analyzed with the thin metal film on top of the resist. Based on above experiment results, the minimum acceptable critical dimensions have been evaluated for variable metal thicknesses on top of the resist. Finally 40nm high density hole and line/space patterns with duty cycle of 50 % have been successfully realized on glass substrate using 15 nm Cr on top of the resist.