An embodiment of a method of forming a portion of a memory array includes forming a conductor with a concentration of germanium that decreases with an increasing thickness of the conductor, removing a portion of the conductor at a rate governed by the concentration of germanium to form a tapered first opening through the conductor, removing a sacrificial material below the conductor to form a second opening contiguous with the tapered first opening, and forming a semiconductor in the contiguous first and second openings, wherein a portion of the semiconductor pinches off within the first opening adjacent an upper surface of the conductor before the contiguous first and second openings are completely filled with the semiconductor.