Three-dimensional nand memory with stacked mono-crystalline channels

Abstract

A three-dimensional (3D) non-volatile memory (NVM) array including spaced-apart horizontally-disposed bitline structures arranged in vertical stacks, each bitline structures including a mono-crystalline silicon beam and a charge storage layer entirely surrounding the beam. Vertically-oriented wordline structures are disposed next to the stacks such that each wordline structure contacts corresponding portions of the charge storage layers. NVM memory cells are formed at each bitline/wordline intersection, with corresponding portions of each bitline structure forming each cell's channel region. The bitline structures are separated by air gaps, and each charge storage layer includes a high-quality thermal oxide layer that entirely covers (i.e., is formed on the upper, lower and opposing side surfaces of) each of the mono-crystalline silicon beams. The 3D NVM array effectively includes multiple NVM NAND string structures, where each NAND string structure is formed by multiple series-connected NVM memory cells disposed along an associated bitline structure.