Abstract: Methods and approaches for fabricating floating gate NAND cells and associated memory devices. A stacked layer structure comprising alternating layers of polysilicon and silicon nitride is fabricated, and an array of memory hole passing vertically through the alternating layers of polysilicon and silicon nitride are formed. Multiple films of materials, such as silicon oxide, silicon nitrides, and polysilicon are sequentially formed over sidewalls of the memory holes during in-memory hole processing. The back-side processing begins with removal of silicon nitride layers (dielectric spacers between wordlines) using an etchant introduced through replacement holes which enables inter-wordline airgaps between FG memory cells in adjacent polysilicon layers. Etching processes selective to silicon oxide and silicon nitride are performed to form the gate, inter-poly dielectric (IPD) layers, and the storage node of the FG memory cells.

Abstract: Methods and apparatus of engineered dielectric profile for high aspect-ratio (AR) 3D NAND structures. The 3D NAND structures comprise a semiconductor structure having multiple stacked memory tiers comprising 2D arrays of memory cells that are charged using vertical structures formed in the semiconductor structure. The memory tiers comprise wordline layers interposed between isolation layers. The vertical structures, such as memory holes or trenches, have a dielectric (e.g., a tunnel dielectric) formed along sidewalls of holes or trenches having a cross-section profile where a thickness of the dielectric at a bottom wordline layer is thicker than the dielectric thickness for at least a portion of wordline layers above the bottom wordline layer. In one example, formation of the tunnel dielectric employs a sandwich design of engineered profile method in which a selective deposition of dielectric is deposited at the bottom sections of the vertical structures while the rest of the structure is un-altered.

Abstract: A vertical channel of a three-dimensional (3D) NAND has a recessed and filled drain/source pocket region for each memory cell to reduce resistance in a region that traditionally has high resistance. The vertical channel conducts current whose resistivity is controlled through a series of memory cells. The vertical channel can have a polysilicon material to conduct current past the memory cell gates and drain/sources region between the memory elements. The recess can extend the polysilicon away from a center of the vertical channel and closer to the control gates. The recess includes a structure to reduce resistance in the drain/source region along the vertical channel between memory cell gates.

Abstract: Storage node configurations are described. A storage node (e.g., a floating gate or a charge trap layer of a three-dimensional (3D) NAND flash device) include a channel-facing surface with a radius of curvature. For example, a channel-facing surface of the storage node may be concave. A control gate-facing surface of the storage node may instead, or additionally, also include a radius of curvature. The radius of curvature of the channel-facing and/or control gate-facing surfaces of the storage node is less than or equal to the radius of the channel layer.