Negative Electron Affinity Based Vacuum Microelectronics Devices

Abstract

A novel cathode technology which integrates stacked electrode structures onto negative electron affinity cathodes has been developed. The process, as shown in Fig. 1, is designed in such a way as to have the emission areas protected throughout the processing steps. With this process a three metal layer structure has been integrated onto a GaAs chip to fabricate an addressable Negative Electron Affinity (NEA) cathode (Fig. 2). This work builds on the process developed recently[ 11 to fabricate patterned cathodes, which demonstrated stable emission and long lifetimes from patterned NEA cathodes. A process to recover the cathode was also developed. The stacked electrode is a sequence of PECVD silicon dioxide/ TiW layers. In previous work[2], it was demonstrated shot noise limited emission, short and long term stabilization of membrane type non patterned cathodes which were activated with same activation procedure and tested in a scanning electron microscope. The patterned cathodes were tested in a UHV (< 2 x 10-”MPa) chamber where they were coated with cesium and oxygen to achieve the NEA condition on the selected areas. Electron emission from the cathodes has been projected onto a phosphorous screen. Simulation and operation of this novel NEA based vacuum microelectronics device will be presented. The ability to selectively emit electrons can have applications in NEA based vacuum microelectronics devices, projection e-beam lithography tools, and combinations of bulk devices with vacuum electronic emitters, which can take advantage of the cold operation, monochromaticity and high brightness of NEA cathodes. (11 Edvd J. P. Santos and Noel C. MacDonald, Tech. Dig. IEDM-92, pp.743-746