A stack of a first hard mask portion and a second hard mask portion is formed over a semiconductor material layer by anisotropically etching a stack, from bottom to top, of a first hard mask layer and a second hard mask layer. The first hard mask portion is laterally recessed by an isotropic etch. A dielectric material layer is conformally deposited and planarized. The dielectric material layer is etched employing an anisotropic etch that is selective to the first hard mask portion to form a dielectric material portion that laterally surrounds the first hard mask portion. After removal of the second and first hard mask portions, the semiconductor material layer is etched employing the dielectric material portion as an etch mask. Optionally, portions of the semiconductor material layer underneath the first and second hard mask portions can be undercut at a periphery.