Integration of microstructures onto negative electron affinity cathodes: Fabrication and operation of an addressable negative electron affinity cathode

Abstract

A new cathode technology which integrates isolated multilayer structures onto negative electron affinity (NEA) cathodes has been developed. The process is designed 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-array NEA cathode. The metal layers are sputter-deposited TiW, the topmost layer is SiN. The addressable-array NEA cathodes were tested in an ultrahigh vacuum chamber, where they were coated with cesium and oxygen to achieve the NEA condition on the lithographically selected areas. Electron emission from the addressable cathodes has been projected onto a phosphorous screen. The photocurrent was modulated by applying a voltage to each control electrode. Pictures demonstrating the addressing capability are presented. The addressable-array NEA cathode technology offers the possibility of new projection electron-beam architectures for high throughput electron-beam lithography.