Method for forming contact hole with high aspect ratio

Abstract

The invention provides a method for forming a contact hole with a high aspect ratio, which comprises the following steps that a substrate is provided, a dielectric layer is formed on the substrate, the dielectric layer comprises a non-easy over-etching region and an easy over-etching region, the dielectric layer comprises at least two sub-dielectric layers, an auxiliary layer is arranged between the sub-dielectric layers and located in the easy over-etching region, the sub-dielectric layer is located in a non-easy over-etching region, and the etching rate of the etching substance to the auxiliary layer is smaller than the etching rate of the etching substance to the dielectric layer; a patterned mask layer is formed on the dielectric layer, the mask layer is provided with a pattern window, and the pattern window exposes the dielectric layer; and the dielectric layer and the auxiliary layer are etched by taking the mask layer as a barrier layer to form the contact hole with the high aspect ratio. The method has the advantages that the auxiliary layer is added in the easy over-etching region of the dielectric layer, so that the resistance of the region to plasma bombardment is enhanced, the region cannot be over-etched by plasma, the subsequent filling of a conductive material cannot be influenced, and the performance of the device is greatly improved.

Description

technical field [0001] The invention relates to the field of semiconductor manufacturing, in particular to a method for forming a contact hole with a high aspect ratio. Background technique [0002] Dynamic Random Access Memory (English: Dynamic Random Access Memory, DRAM for short) is a semiconductor memory widely used in multi-computer systems. The DRAM structure includes transistors, word lines, bit lines, capacitors, metal interconnects, and peripheral regions. [0003] With the improvement of the integration level of the semiconductor process, the line width of the device will be further reduced, and the aspect ratio of the contact hole in the semiconductor process will continue to increase. When making high-aspect-ratio contact holes, the sidewall (profile) will appear bow-shaped (bow), and cause the bottom critical dimension (bottom CD) to be small, which will affect the filling of conductive materials in subsequent contact holes, increase RC delay, and affect devic...

AI Technical Summary

Problems solved by technology

[0009] It can be seen that the etching-filling-etching-refilling (etch-dep-etch-dep) method is used in the prior art to avoid the influence of the bow-shaped bending of the sidewall of the contact hole on the filling of the conductive material, but this method increases the The process cycle reduces production capacity and efficiency, and it is necessary to optimize the process to improve production efficiency

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