Forming method of 3D NAND memory

Abstract

The invention discloses a forming method of a 3D NAND memory. The method comprises the steps of providing a semiconductor substrate, wherein a stacking structure is formed on the semiconductor substrate and comprises a plurality of sacrificial layers and isolation layers which are alternately stacked; the stacking structure is provided with a first channel hole and a second channel hole which communicate with each other, the second channel hole is aligned and deviated relative to the first channel hole, a step is formed at the junction of the first channel hole and the second channel hole, andthe first channel hole is filled with a sacrificial material layer; forming a side wall on the side wall of the second channel hole; etching the first channel hole to enable the width of the first channel hole to be widened and enable the width of the step to be reduced; forming charge storage layers on the side walls and the bottoms of the first channel hole and the second channel hole; forminga channel hole sacrificial layer on each charge storage layer; and sequentially etching the channel hole sacrificial layer and the charge storage layer on the bottom of the first channel hole to forman opening. The method provided by the invention prevents the charge storage layer at the step from being etched or damaged, thereby preventing the memory from failing.

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

Images