The invention relates to a method for producing a semiconducting structure on a semiconducting substrate, one surface of which has a topology, this method including:a) a step for forming a first layer (24) in a first insulating material on said surface,b) a step for forming a second layer in a second insulating material (28), less dense than the first insulating material, with a thickness between 2.5 p and 3.5 p,c) a step for planarization of the assembly.