Assembly of an aperture plate system for projection mask-less lithography

Mask-less lithography becomes more and more important to reduce cycle time and lithography costs for device prototyping and small batch ASIC manufacturing. A European consortium is developing an electron multi beam technology - called projection mask-less lithography (PML2)-for the 45 nm, 32 nm node and beyond. The multi beam blanking device (programmable "aperture plate system"-APS) is one of the challenging key elements of PML2 [H.-J. Döring et al., Proc. SPIE 5751 (2005); C. Brandstätter et al., Proc. SPIE 5835 (2005)]. This paper will focus on the precision assembly concept and the alignment procedure of the aperture plate system. Major system specifications and their influence on the sub-µm assembly and alignment accuracy will be discussed in the context of mechanical, thermal and magnetic constraints.