A new class of negative-tone resist materials has been developed for electron beam and extreme ultraviolet lithography. The resist is based on heterometallic rings. From initial electron beam lithography studies, the resist performance demonstrated a resolution of 40-nm pitch but at the expense of a low sensitivity. To improve the sensitivity, we incorporated HgCl2 and HgI2 into the resist molecular design. This dramatically improved the resist sensitivity while maintaining high resolution. This improvement was demonstrated using electron beam and extreme ultraviolet lithography.