A floating gate structure and a method for forming a floating gate oxide layer comprising the following steps. A structure having a first dielectric layer formed thereover is provided. An oxide layer is formed over the first dielectric layer. A nitride layer is formed over the oxide layer. The nitride layer is patterned to form an opening exposing a portion of the oxide layer. A portion of the first dielectric layer is exposed by removing: the exposed portion of the oxide layer; and portions of the oxide layer underneath the patterned nitride layer adjacent to the opening to form respective undercuts. The exposed portion of the first dielectric layer is oxidized to form the floating gate oxide layer.