A kind of polysilicon etching method

Abstract

The invention provides a polysilicon etching method. The method comprises the following steps of S1, forming a SiN layer on the surface of a polysilicon layer, etching the SiN layer and patterning the SiN layer to obtain a SiN hard mask layer; S2, forming an oxide layer between SiN residual particles which are not etched thoroughly and on the periphery of the SiN hard mask layer and the polysilicon layer; S3, adopting wet etching to remove the oxide layer, and enabling the SiN residual particles to separate from the polysilicon layer due to suspension; and S4, etching the polysilicon layer taking the SiN hard mask layer as a mask layer. The invention prevents that fact that silicon nitride residual particles obstruct follow-up polysilicon etching, and greatly reduces polysilicon residual defects. With the polysilicon etching method, the photoetching time is not required to be increased, almost no influence on subsequent processes exists, disadvantages of using the traditional DARC as a hard mask layer are successfully avoided, polysilicon residual defects as the SiN serves as the hard mask layer are successfully reduced, and the product yield rate is effectively raised.

Description

technical field [0001] The invention belongs to the field of semiconductor manufacturing and relates to a polysilicon etching method. Background technique [0002] In conventional semiconductor manufacturing processes, polysilicon (polysilicon) is often used as a gate of a MOS device. The formation of the gate often requires the use of silicon nitride (SiN) as a hard mask (Hardmask, HM). Silicon nitride as a hard mask solves the problem that traditional DARC (SiON) as a hard mask is difficult to remove (phosphoric acid is ineffective) after a subsequent high-temperature process. [0003] At present, a MOS device structure formed by double-layer polysilicon can effectively reduce the area of ​​the device, and this unique process has attracted more and more attention. Silicon nitride is also used as a hard mask material in this double-layer polysilicon device. However, in the silicon nitride hard mask process, it is easy to produce a large number of tiny polysilicon residue...

AI Technical Summary

Problems solved by technology

[0007] In view of the above-mentioned shortcomings of the prior art, the purpose of the present invention is to provide a polysilicon etching method for solving the problem of SiN residual particles formed during the etching process of the SiN hard mask in the prior art, resulting in a polysilicon etching process Unnecessary polysilicon residues are generated in the middle, which reduces the problem of product yield

Images