Experimental evaluation of a 20x20 mm footprint microcolumn

A miniaturized 1 kV electron beam column with a 20x20 mm square footprint for application in arrayed lithography was developed. The actual beam forming optics measured from the electron emitter to the last electrode in the beam focusing Einzel lens is only 3.5 mm in length. The electron source is a miniaturized, high brightness (120 mu A/sr), low heating power (<1.5 W) Zr/O/W Schottky field emitter that provides a stable beam current with <1%/h current fluctuations. A custom designed, ultralow profile (0.8 mm high) annular microchannel plate (MCP) detector is fitted into the working distance, which can be varied between 1 and 5 mm, between the Einzel lens and the sample. The MCP provides a high gain, up to 3x10(4), detector for secondary and backscattered electron detection from solid samples. The beam is scanned over the sample using a prelens double octupole deflector for large field size, greater than or equal to 100 mu m, at low distortions and low deflection aberrations. Using a computer controlled digital pattern generator, patterns with less than 100 nm linewidth were exposed in polymethylmethacrylate resist and reactively ion etched into an underlying tungsten layer. (C) 1996 American Vacuum Society.