A method is provided for etching a dielectric layer covering a top and a flank of a three-dimensional structure, the method including: a first etching of the dielectric layer, including: a first fluorine-based compound and oxygen, the first etching being performed to: form a first protective layer on the top and form a second protective layer on the dielectric layer, a second etching configured to remove the second protective layer while retaining a portion of the first protective layer, the first and the second etchings being repeated until removing the dielectric layer located on the flank of the structure, and before deposition of the dielectric layer, a formation of an intermediate protective layer between the top and the dielectric layer.