EVALUATION OF CRITICAL DESIGN PARAMETERS OF AN ION PROJECTOR FOR 1-GBIT DRAM PRODUCTION

The Advanced Lithography Group (ALG) a consortium of industry and univ ersity institutes in the US and Europe has the aim to produce an Ion p rojection lithography tool ALG-1000 for 0.18 mum geometry and below. T he base of the machine is a new ion optical column developed by IMS, V ienna for exposing 20 mm x 20 mm fields at 3x reduction. The errors of the first two lenses (diverging lens and field lens) are fully compen sated in 3rd order by an asymmetric Einzellens projecting an ion image of the stencil mask onto the wafer substrate with better than 2 mrad telecentricity. Remaining are errors of 5th order resulting in minimum calculated distortions of less than 30 nm. Space charge effects have been investigated with high transparency masks in two different ion pr ojects. An indication for a space charge effect was observed in the ca se of the Alpha 5x system with a crossover energy of 7.5 keV if the be am current was raised above 10 nA. The experiments with the IPLM-02 sy stem with a crossover at approximately 50 keV, more representative for the conditions in the ALG-1000 with a crossover energy of 200 keV, al lowed the resolution of 0.18 mum lines and spaces even at high current s of up to 2 muA.