3D memory device and manufacturing method thereof

Abstract

Disclosed is a 3D storage device and a manufacturing method thereof. The 3D storage device includes: a substrate; a stacked gate structure located above the substrate, and the stacked gate structure includes a plurality of interlayer insulating layers and a plurality of gate conductors stacked alternately ; a plurality of channel pillars running through the gate stack structure, the channel pillars include a functional layer located on the sidewall of the channel pillar and a channel layer; a silicon groove is formed by removing the functional layer at the bottom of the channel pillar; an epitaxial layer is located on the silicon In the groove; the surface screens on both sides of the silicon groove are between the surface planes of the bottom two layers of gate conductors in the gate stack structure; part of the channel layer is located in the silicon groove. In the embodiment of the present invention, the functional layer at the bottom of the channel hole is removed to form a silicon groove, and an epitaxial layer is formed in the silicon groove; since the functional layer has no corners, it is only located on the sidewall of the channel hole, which improves the charge-trapping ability of the charge storage layer, The charge on the charge storage layer is prevented from leaking into the channel layer, thereby improving the stability of the threshold voltage of the bottom select gate of the 3D memory.

Description

technical field [0001] The invention relates to the technical field of memory, in particular to a 3D memory device and a manufacturing method thereof. Background technique [0002] The improvement of the storage density of the memory device is closely related to the progress of the semiconductor manufacturing process. As the aperture of the semiconductor manufacturing process becomes smaller and smaller, the storage density of the memory device becomes higher and higher. In order to further increase storage density, memory devices with a three-dimensional structure (ie, 3D memory devices) have been developed. A 3D memory device includes a plurality of memory cells stacked in a vertical direction, which can double the integration level on a wafer per unit area and reduce the cost. [0003] The formation process of the existing 3D NAND memory generally includes: forming a stacked layer in which silicon nitride layers and silicon oxide layers are alternately stacked on a subs...

AI Technical Summary

Problems solved by technology

Due to the poor charge confinement ability of the bottom select gate (BSG), the charges on the charge storage layer can easily leak into the channel layer, which will cause the threshold voltage Vt of the bottom select gate BSG to shift, affecting the performance of 3D memory devices. , especially during erase or read / write

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