Method of manufacturing memory device

Abstract

A method of manufacturing a memory device includes providing a substrate, forming a stack layer on the substrate, and forming a hard mask layer on the stack layer. The hard mask layer has a protrusion. The method includes forming a patterned mandrel on the hard mask layer, the patterned mandrel includes a first mandrel disposed adjacent to the protrusion, a second mandrel disposed on the top surface of the protrusion, and a third mandrel. The method further includes using the patterned mandrel as a mask, the hard mask layer and the stack layer are sequentially patterned to form a dummy structure and a word line structure on the substrate. The portion of the stack layer corresponding to the first and second mandrels is formed as the dummy structure. The portion of the stack layer corresponding to the third mandrel is formed as the word line structure.