US Patent 8409456 Planarization method for high wafer topography

A method for planarizing a semiconductor device includes providing a substrate having at least one opening therein, each opening defining a lower portion and an upper portion; coating a light sensitive material layer over the substrate, the light sensitive material layer covering the lower and upper portions of the at least one opening; etching back the light sensitive material layer to expose the upper portion of the at least one opening; repeating the steps of coating and etching to remove a predetermined amount below the upper portion of the at least one opening; depositing an insulating layer over the substrate; and planarizing the insulating layer until the upper portion of the at least one opening is exposed.