Double-gated field emission arrays

Abstract

There is a need for massively parallel, individually addressed and focused electron sources for applications such as flat panel displays, mass storage and multi-beam electron beam lithography. This project fabricates and characterizes double-gated field emission devices with high aspect ratio. One of the gates extracts the electrons while the second gate focuses the electrons into small spots. High aspect ratio silicon field emitters were defined by reactive ion etching of silicon followed by multiple depositions of polycrystalline oxide insulators and silicon gates. The layers were defined by a combination of lithography, chemical mechanical polishing and micromachining. We obtained devices with gate and focus apertures of 0.4[mu]m and 1.2[mu]m diameter. The anode current has very little dependence on the focus voltage and the ratio of the focus field factor to the gate field factor βF / βG is 0.015. Scanning electron micrographs of the devices, numerical simulation and spot size measurements on a phosphor screen confirmed these results. An e-beam resist, PMMA, was successfully exposed using the FEA device as an electron source.