Process optimization and diffusion length evaluation of a new aqueous base developable negative epoxy electron beam resist

A new aqueous base developable, chemically amplified negative resist based on epoxy chemistry (ADEPR) is evaluated for high resolution, high-speed e-beam lithography. The acid diffusion coefficient of this system is also evaluated. This resist is formulated using partially hydrogenated poly(hydroxy styrene) and epoxy novolac polymers. The absence of swelling phenomena compared to pure epoxy systems allows lithography up to 100 nm regime and a sensitivity of 4-8 μC/cm² at 50 KeV. Both high-resolution line and dot exposures were used in order to evaluate the diffusion coefficient. The value of D=5.10^-14 cm²/sec fount is a little higher than its pure epoxy counterpart (EPR) but still lower than other commercial resists