Formation method of semiconductor structure

Abstract

The present invention relates to a method for forming a semiconductor structure. The method for forming a semiconductor structure includes: providing a substrate, the substrate has a first surface, and a stack structure is formed on the first surface of the substrate; etching the In the above stacked structure, a channel hole is formed through the stacked structure, the bottom surface of the channel hole exposes the first surface of the substrate or the bottom surface of the channel hole is located in the substrate and lower than the substrate the first surface of the channel hole, the distance between the bottom surface of the channel hole and the first surface of the substrate is less than a preset value; post-etching treatment is performed on the bottom of the channel hole to remove the substrate at the bottom of the channel hole Impurities and defects on the bottom surface; an epitaxial semiconductor layer is formed on the substrate surface at the bottom of the channel hole. The methods described above can enhance the performance of the formed semiconductor structures.

Description

technical field [0001] The invention relates to the technical field of semiconductors, in particular to a method for forming a semiconductor structure. Background technique [0002] In recent years, the development of flash memory (Flash Memory) is particularly rapid. The main feature of flash memory is that it can keep stored information for a long time without power on, and has the advantages of high integration, fast access speed, easy erasing and rewriting, etc. Has been widely used. In order to further increase the bit density (Bit Density) of the flash memory while reducing the bit cost (Bit Cost), three-dimensional flash memory (3D NAND) technology has been developed rapidly. [0003] In the process of forming a 3D NAND memory, it is necessary to form a stacked structure of a sacrificial layer and an insulating layer on the surface of the substrate, and then etch the stacked structure to form a channel hole, and form a channel hole in the channel hole Structure, as...

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Problems solved by technology

Therefore, the damage and oxide layer on the bottom surface of the opening at the bottom of the channel hole are easily removed, while the damage and oxide layer on the side wall surface of the opening cannot be completely cleaned.

In the subsequent process of forming the epitaxial semiconductor layer at the bottom of the channel hole, due to the damage or oxide layer on the surface of the side wall of the opening, the side wall of the formed epitaxial semiconductor layer will have defects such as holes, which will affect the quality of the formed epitaxial semiconductor layer

Moreover, since the sidewall of the epitaxial semiconductor layer is connected to the sacrificial layer at the side of the channel hole, in the subsequent process of replacing the sacrificial layer with a metal gate, the metal gate material is easy to enter into the sidewall of the epitaxial semiconductor layer. In the hole, the gate leakage problem of the bottom select transistor of the memory is caused, thereby affecting the performance of the memory

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