ELECTRON OPTICS FOR MULTI-BEAM ELECTRON BEAM LITHOGRAPHY TOOL

摘要

A charged particle optical column capable of being used in a high throughput, multi-column, multi-beam electron beam lithography system is disclosed herein. The column has the following properties: purely electrostatic components; small column footprint (20 mm square); multiple, individually focused charge particle beams (220); telecentric scanning of all beams simultaneously on a wafer (242) for increased depth of field; and conjugate blanking of the charged particle beams for reduced beam blur. An electron gun (250) is disclosed that uses microfabricated field emission sources (202, 204, 206, 208) and a microfabricated aperture-deflector assembly (214, 216, 218, 228, 230). The aperture-deflector assembly (214, 216, 218, 228, 230) acts as a perfect lens in focusing, steering, and blanking a multiplicity of electron beams (220) through the back focal plane of an immersion lens (238) located at the bottom of the column. Beam blanking can be performed using a gating signal to decrease beam blur during writing on the wafer (242).