Multiplexed blanker array for parallel electron beam lithography

Abstract

Alternative electron beam technologies to conventional single beam systems have the potential to increase beam current by an order of magnitude, into the 1–10 μA range. The technique we are investigating is to insert an aperture array at an object plane in a lithography system, thus creating an array of beamlets which are imaged as a dot matrix. Each aperture is surrounded by an independently controlled electrostatic microblanker which can modulate the beamlet passing through the aperture in conjuction with a blanking aperture placed at a crossover further down the column. An existing 20 kV shaped beam column with a LaB6 source providing 5 μA of illumination current over a 150 μm×150 μm square area is used as a test stand. The column is used to test prototype microblanker chips. Power dissipation calculations show less than a 10 K temperature rise over the prototype chips. Work has begun on a second generation prototype blanker array which will overcome many of the processing difficulties encountered with the first prototype. Specifically, the new all-silicon process will allow fabrication of smaller apertures which require less demagnification and a shorter electron-optical column.