Arrayed miniature electron beam columns

Abstract

This paper discusses the development of a new approach based on scanning tunneling microscope (STM), microfabricated lenses and field emission technology to form an exceptionally high brightness electron source and miniaturized electron probe forming columns. Electron optical studies have shown that such miniaturized columns, measuring millimeters in length and diameter, can have performance surpassing conventional columns at the same potential. Processes for fabricating microlenses from silicon membrane using electron beam lithography and reactive ion etching (RIE), and a special W <111> field emission tip preparation and annealing procedure have been developed. Prototype 1kV microcolumns based on this concept measuring 2.5 mm have been successfully fabricated and demonstrated to be fully operational. Scanning electron microscope images in the transmission mode have been achieved. The expected performance of such microcolumns coupled with the very significant reduction in physical column size can open new possibilities in many applications which include lithography, microscopy, metrology, testing, storage, etc.. It can be shown that by the use of an array of these miniaturized columns, high throughput sub-100nm lithography can be achieved. © 1993.