An electronic fuse for an integrated circuit and a method of fabrication thereof are presented. The electronic fuse has a first terminal portion and a second terminal portion interconnected by a fuse element. The fuse element has a convex upper surface and a lower surface with a radius of curvature at a smallest surface area of curvature less than or equal to 100 nanometers. Fabricating the electronic fuse includes forming an at least partially freestanding dielectric spacer above a supporting structure, and then conformably forming the fuse element of the fuse over at least a portion of the freestanding dielectric spacer, with the fuse element characterized as noted above. The dielectric spacer may remain in place as a thermally insulating layer underneath the fuse element, or may be removed to form a void underneath the fuse element.