Micron Technology, Inc.
STORAGE NODE AFTER THREE-NODE ACCESS DEVICE FORMATION FOR VERTICAL THREE DIMENSIONAL (3D) MEMORY

Abstract:

Systems, methods and apparatus are provided for storage node after horizontally oriented, three-node access device formation in vertical three dimensional (3D) memory. An example method includes a method for forming arrays of vertically stacked memory cells, having horizontally oriented access devices and vertically oriented access lines. The method includes depositing alternating layers of a dielectric material and a sacrificial material to form a vertical stack. A plurality of first vertical openings are formed through the vertical stack to form elongated vertical, pillar columns with sidewalls in the vertical stack. A first conductive material is conformally deposited on a gate dielectric material in the first vertical openings. Portions of the first conductive material are removed to form a plurality of separate, vertical access lines along the sidewalls of the elongated vertical, pillar columns. A second vertical opening is formed through the vertical stack to expose a first region of the sacrificial material. The first region is selectively removed to form a first horizontal opening in which to form a first source/drain material, a channel material, and a second source/drain material of the three-node access device. A third vertical opening is formed through the vertical stack to expose a second region of the sacrificial material. The second region is selectively removed after formation of the three-node access device in the first region to form a second horizontal opening in which to form a storage node electrically coupled to the first source/drain material.