Sub-50nm resolution surface electron emission lithography using nano-Si ballistic electron emitter

Abstract

It is demonstrated that parallel electron beam lithography using a nano-Si planar ballistic electron emitter (PBE) provided the resolution below 30nm even in a low accelerating voltage. This high resolving power is explained by the nature of ballistic electron transport in nanocrystalline silicon. The parallel EB lithography was performed on a 1:1 electron imaging system. The system was composed of the PBE as a patterned surface electron source, a target wafer parallel to the surface electron source, and vertical electromagnetic fields. The PBE projected a patterned electron image on the target. A replica of the pattern was transferred into a resist on the target wafer within less than 1s. The experimental exposure was performed over 10mm2 area. The PBE was composed of a thin metal surface electrode, nanosilicon layer, and semiconductor substrate. The electrons injected from semiconductor substrate were accelerated via cascade tunneling through the nanosilicon layer and reached the outer surface as ballistic or quasiballistic electrons. As a result, the chromatic aberration limiting resolution is expected to be quite small. The 1:1 electron imaging system based on the PBE provides promising solution for high resolution and high throughput lithography with low cost system with the simple electron optics for the next generation device fabrication in the sub-30nm scale.