A method is presented for preventing fin erosion. The method includes forming a plurality of hardmasks over a plurality of fin structures, trimming the plurality of fin structures such that the plurality of hardmasks are wider than the plurality of fin structures, forming a dielectric liner adjacent sidewalls of the plurality of fin structures, and depositing a dielectric between the plurality of fin structures. The method further includes directionally etching the dielectric to form recesses between the plurality of fin structures and isotropically etching dielectric remaining regions directly underneath the plurality of hardmasks such that upper corners of the plurality of fin structures remain in an undamaged state.