Microelectron field emitter array with focus lenses for multielectron beam lithography based on silicon on insulator wafer

We report on a device concept, results of fabrication, and characterization of a monolithic electron field emitter array with focus lenses for multielectron beam lithography and high-density nano data storage. An array of individually addressable emitters of various materials was patterned on oxidized etch pits of a silicon on insulator (SOI) wafer. Si active layer of the SOI with gate hole array that self-aligned with the emitters was used as a common gate electrode. An array of cylindrical holes formed at the Si base of the SOI was used as a common lens electrode. For a single Pt emitter with gate hole of 2 μm diameter, the emission current started at a gate voltage Vgate=90 V and reached to 1.2 μA current and 0.84 mW beam power at Vgate=300 V and anode voltage Vanod=0.7 kV. The emission current was found to be stable with a fluctuation smaller than 10%/h. The emitter-gate and emitter-lens leak currents were found to be less then 1% compared with the emission current. The focusing characteristic of the device was experimentally confirmed by observing emission patterns on a phosphor anode screen. A simulation work using a finite-element method has shown that the emitted electron beam with emission cone angle within 15° can be focused at a spot of 40 nm diameter and 200 μm focal length at a lens voltage Vlens=−6 V.