Metal grid electrode preparation method of 3D NAND memory

Abstract

The invention provides a metal grid electrode preparation method of a 3D NAND memory. The metal grid electrode preparation method of a 3D NAND memory comprises steps of providing a substrate, wherein a silicon oxide layer / silicon nitride layer alternative staking structure and a grid line gap going through the silicon oxide layer / silicon nitride layer alternative stacking structure are formed on the substrate, adopting an etching solution with a selection ratio of the silicon nitride to the silicon oxide greater than 1 to etch the silicon nitride layer in the silicon oxide layer / silicon nitride layer alternative staking structure, forming a hollowed area in a 303 position of the silicon nitride layer, removing silicon dioxide which is a side product during the silicon nitride layer etching process, and filling the hollow area with a metal medium to form the metal grid electrode. The metal grid electrode preparation method of the 3D NAND memory can remove the side product silicon dioxide which is generated during the process of etching the silicon nitride before filling with metal medium. As a result, the opening of the position filled with the metal medium is not blocked by the side product, and the opening of the area filled with the metal medium is not reduced. The metal grid electrode preparation method of the 3D NAND memory reduces the possibility of forming an gap inside the metal grid electrode and can improve the performance of the 3D NAND memory.

Description

technical field [0001] The present application relates to the technical field of semiconductor processing, in particular to a method for preparing a metal gate of a 3D NAND memory. Background technique [0002] The vertical storage structure of the existing 3D NAND storage device is formed by stacking multi-layer dielectric films. During its preparation, it is necessary to remove the silicon nitride in the alternate stacked structure of silicon oxide / silicon nitride and fill it with a metal medium to form a metal dielectric. grid. [0003] At present, the removal of silicon nitride in the silicon oxide / silicon nitride alternating stacked structure is generally accomplished by a wet etching process. The wet etching solution gradually diffuses from the gate line slit (GLS) to the inside of the stacked structure, so as to gradually remove the silicon nitride in the stacked structure. [0004] However, in the existing wet etching process for removing silicon nitride, phosphori...

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Problems solved by technology

[0005] This "match head" structure leads to a reduction in the opening of the subsequent metal dielectric filling, thus hindering the filling of the subsequent metal dielectric, which easily leads to the presence of voids inside the formed metal gate, which ultimately affects the performance of the storage device

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