The influence of the development process on the ultimate resolution of electron beam lithography using ultrathin HSQ layers was studied. Different developers, of different types and strengths, were used to develop lines exposed at a variety of doses. Optimum exposures could be found for lines of widths between 7 and 12 nm, at a pitch of 20 nm. Lines smaller than 5 nm could not be fabricated using any of these developers. Changing the development time had no influence on this result. Width versus dose curves are presented for all three developers and a 60 s development time. A scaling is presented to enable an easy calculation of the exposure latitude for each linewidth. Using 100 keV electron beam lithography, we achieved 6 nm isolated features in a 10 nm thick HSQ layer on a silicon substrate. We also showed that dense structures (5 nm wide at a pitch of 20 nm) could be obtained using a 1:5 developer solution of Microposit 351:H2O. (c) 2007 American Vacuum Society.