Manufacturing method of three-dimensional memory

Abstract

The invention provides a manufacturing method of a three-dimensional memory. The method is used in a process of forming sacrificial layers. The top sacrificial layer has a first etching selection ratio A for the bottom sacrificial layer; the top sacrificial layer has a second etching selection ratio B for the middle sacrificial layer; A and B satisfy a relational expression that: A<= B<=1, and A is not equal to 1; and therefore, material components are changed in the deposition stage of the sacrificial layers; the etching rate of the sacrificial layers is changed in the process of removing thesacrificial layers by wet etching; the etching rate of the sacrificial layer on the lower layer is higher than that of the sacrificial layer on the upper layer; the difference of the etching rates can balance the difference of the etching rates of the lower sacrificial layer and the upper sacrificial layer caused by an etching load effect in the process; damage to part of a charge barrier layer in contact with the upper sacrificial layer is reduced; the problem of uneven damage of the charge barrier layer at the upper position and the lower position is effectively solved; and the step coverage capacity of the charge barrier layer at the upper position and the lower position is improved.

Description

technical field [0001] The invention relates to the technical field of semiconductors, in particular to a method for manufacturing a three-dimensional memory. Background technique [0002] In the prior art, the main function of flash memory (Flash Memory) memory is to keep stored information for a long time without power on. It has the advantages of high integration, fast access speed, and easy erasing and rewriting. Widely used in electronic products. In order to further increase the bit density (Bit Density) of the flash memory while reducing the bit cost (Bit Cost), a three-dimensional NAND flash memory is further proposed. [0003] The storage structure is the key structure of the three-dimensional memory. Commonly used storage structures include a charge blocking layer, a charge trapping layer, a tunneling layer and a channel layer, which function to control the charge storage of the memory. At present, the manufacturing process of the storage structure in the three-d...

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Problems solved by technology

[0009] The main purpose of the present invention is to provide a method for manufacturing a three-dimensional memory, to solve the problem that the manufacturing process of the three-dimensional memory in the prior art may easily lead to the background of the upper word line (WL). The problem of high leakage risk of the gate

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