Field size versus column shortness in high throughput electron beam lithography

In electron beam projection systems there are competing requirements for co lumn length. Shorter lengths lead to reduced space charge interactions whil e Longer columns allow larger field sizes. Other parameters include the con vergence angle and beam voltage. We have used a generic 4:1 reduction telec entric system as a test vehicle to study these tradeoffs. To determine the lens aberrations we employed a thick lens configuration with constant magne tic fields; space charge blur was estimated with a Monte Carlo simulation u sing a thin lens approximation. For a given beam voltage V, held size F, co nvergence angle alpha, and current I, there is a maximum value of column le ngth L that satisfies a given resolution requirement. For example, if V=100 kV and 1=20 mu A then L must be less than 30 cm for 100 nm resolution. The use of a retarding field just upstream of the target can lead to greatly i mproved performance in terms of resolution, field size, and throughput; e.g ., the minimum resolved feature size is approximately proportional to the r atio of landing voltage over beam voltage. (C) 1999 American Vacuum Society . [S0734-211X(99)09406-8].