Forming method of 3D NAND storage

Abstract

The invention relates to a forming method of a 3D NAND storage. The forming method comprises the steps of: providing a semiconductor substrate, wherein a stacked structure comprising a plurality of sacrificial layers and isolation layers, which are alternatively stacked, is formed on the semiconductor substrate, a first channel hole and a second channel hole which are communicated are formed in the stacked structure, the second channel hole has an alignment offset relative to the first channel hole, a step is formed at a junction of the first channel hole and the second channel hole, and the first channel hole is full filled with a sacrificial material layer; forming a side wall on the side wall of the second channel hole; removing a part of the sacrificial material layer; etching the first channel hole to increase a width of the first channel hole and reduce a width of the step; forming charge storage layers on the side walls and at the bottoms of the first channel hole and the secondchannel hole; forming channel hole sacrificial layers on the charge storage layers; and sequentially etching the channel hole sacrificial layer and the charge storage layer at the bottom of the firstchannel hole so as to form an opening. By the method provided by the invention, the charge storage layers at the step are prevented from being etched off or damaged so as to prevent a failure of thestorage.

Description

technical field [0001] The invention relates to the field of semiconductor manufacturing, in particular to a method for forming a 3D NAND memory. Background technique [0002] NAND flash memory is a better storage device than hard disk drives, and it has been widely used in electronic products as people pursue non-volatile storage products with low power consumption, light weight and high performance. At present, the NAND flash memory with a planar structure is close to the limit of practical expansion. In order to further increase the storage capacity and reduce the storage cost per bit, a 3D NAND memory with a 3D structure is proposed. [0003] The manufacturing process of the existing 3D NAND memory includes: providing a substrate on which a stacked structure in which isolation layers and sacrificial layers are alternately stacked; etching the stacked structure to form an exposed substrate surface in the stacked structure channel hole; form a storage structure in the cha...

AI Technical Summary

Problems solved by technology

[0004] In order to further increase the storage capacity, when forming the stack structure in the prior art, a multi-layer stack structure is usually formed, and each layer stack structure includes several alternately stacked sacrificial layers and isolation layers. In the multi-layer stack structure A channel hole is formed; a storage structure is formed in the channel hole, but this storage structure still has the problem of failure

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