Bottom-Up Approach To High Aspect Ratio Hole Formation In 3D Memory Structures

Methods of forming memory structures are described. A metal film is deposited in the features of a structured substrate and volumetrically expanded to form pillars. A blanket film is deposited to a height less than the height of the pillars and the blanket film is removed from the top of the pillars. The height of the pillars is reduced so that the top of the pillars are below the surface of the blanket film and the process is optionally repeated to form a structure of predetermined height. The pillars can be removed from the features after formation of the predetermined height structure to form high aspect ratio features.