Method for forming semiconductor structure

Abstract

The invention discloses a method for forming a semiconductor structure, which comprises the following steps: providing a substrate and forming a dielectric layer on the substrate; forming a mask layer provided with an opening for exposing the surface of the dielectric layer on the dielectric layer; carrying out a plasma etching on the dielectric layer by taking the mask layer as a mask, wherein a bias power source outputs a bias power in pulse mode, when the bias power resource is switched on, etching part of the dielectric layer to form an etch-hole, when the bias power resource is switched off, forming a polymer on the surface of the mask layer, repeating the process of switching on the bias power resource and switching off the bias power resource till a through hole is formed. When forming the through hole, the etching step and the polymer forming step are repeated so that the polymer can keep a certain thickness, therefore, in the entire etching process, the mask layer is protected from damaging or the damage rate is reduced, and the etching ratio of the dielectric layer relative to the mask layer is increased.

Description

technical field [0001] The invention relates to the field of semiconductor manufacturing, in particular to a method for forming a semiconductor structure. Background technique [0002] With the development of integrated circuits to sub-micron dimensions, the density of devices and the complexity of processes are increasing, and strict control of the process becomes more important. Among them, the through hole is used as the interconnection between the multilayer metal layers and the connection channel between the active area of ​​the device and the external circuit. Due to its important role in the composition of the device structure, the formation process of the through hole has always been a technical skill in the art. personnel's attention. [0003] Figure 1~Figure 3 It is a structural schematic diagram of the existing through-hole forming process. [0004] refer to figure 1 , providing a semiconductor substrate 100, forming a dielectric layer 101 on the semiconducto...

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Problems solved by technology

[0006] However, it is found in actual production that as the size of the device shrinks, the size of the through hole also shrinks, especially when the existing plasma etching process is used to form a through hole with a high aspect ratio. As the etching progresses, the gas exchange in the through hole becomes slower and slower, so it is necessary to strengthen the bias power to enhance the gas exchange and the reaction rate in the through hole, and the increase of the bias power makes the high energy during etching The physical bombardment of ions becomes stronger, and the mask layer 102 will become thinner or damaged (refer to image 3 ), the thinning or damage of the mask layer will reduce the etching selectivity ratio of the dielectric layer relative to the mask layer, which will cause the deformation of the through hole formed by etching or the bridging between adjacent through holes

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