Methods for fabricating a semiconductor FIN structure with smooth sidewalls and rounded top corners and edges is disclosed. A method includes forming a plurality of semiconductor FIN structures. A sacrificial oxide layer is formed on the top surface and the sidewall surfaces of the plurality of semiconductor FIN structures for rounding the corners and edges between the top surfaces and the sidewall surfaces of the plurality of semiconductor FIN structures. The sacrificial oxide layer is removed with a high selectivity oxide etchant. The plurality of semiconductor FIN structures are annealed in a hydrogen environment. A tunnel oxide is formed over the plurality of semiconductor FIN structures.