Formation method of 3D NAND memory

Abstract

A formation method of a 3D NAND memory comprises the steps of: providing a semiconductor substrate, forming a stacked structure on the semiconductor substrate, wherein the stacked structure comprisesa plurality of alternately stacked sacrificial layers and isolation layers, the stacked structure comprises a first channel hole and a second channel hole, the second channel hole communicates with the first channel hole, the second channel hole has an alignment offset relative to the first channel hole, and a step is formed at the junction of the first channel hole and the second channel hole; etching the step to slow down the gradient of the step; after the step is etched, forming a charge storage layer at the side walls and the bottom portions of the first channel hole and the second channel hole; forming a channel hole sacrificial layer on the charge storage layer; and etching the channel hole sacrificial layer and the charge storage layer at the bottom portion of the first channel hole in order to form an opening. The formation method of the 3D NAND memory can prevent the charge storage layer at the step from being broken by cutting or being damaged so as to avoid failure of the memory.

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...

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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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