Photoresist removal method

Abstract

The invention discloses a method for removing photoresist. The method includes steps of firstly, forming the photoresist on the surface of a silicon substrate, performing photolithography to open theion implantation region of a semiconductor device, and performing ion implantation by using the photoresist as a mask; secondly, removing the photoresist by the aid of an ashing process, wherein the photoresist is divided into a bottom region and a top region which are stacked to form the photoresist in the ashing process, and non-oxygen nitrogen-containing gas is used during the bottom region removing in the ashing process after the top region is removed; removing the bottom region by the aid of nitrogen-containing gas contained in the non-oxygen nitrogen-containing gas, wherein the residualphotoresist can be in contact with the silicon of the silicon substrate when the bottom region is removed, and spherical defects formed by reaction between oxygen and the silicon under the condition that the residual photoresist is in contact with the silicon can be prevented by the oxygen-free characteristic of the non-oxygen nitrogen-containing gas. The method has the advantages that the spherical defects in the photoresist removing process can be prevented, especially the spherical defects in technical nodes smaller than 28 nanometers can be eliminated, and the method is high in photoresistremoving rate and simple in process.

Description

technical field [0001] The invention relates to a method for manufacturing a semiconductor integrated circuit, in particular to a method for removing photoresist. Background technique [0002] After entering the 28nm and 20nm technology nodes, due to the increase in process complexity, defects that had no impact on the yield rate at the previous technology node may have a lethal impact on the yield rate after entering the 28nm technology node; the corresponding technology node in the integrated circuit manufacturing process on the feature size. Taking spherical defects as an example, thick photoresists, that is, photoresists, have relatively high requirements for dry etching and ashing due to their high viscosity. Therefore, dry etching and ashing of thick photoresist needs to be carried out at a relatively high temperature and in an oxygen-rich environment. In this environment, the residues in the photoresist will contact the silicon substrate and form a nucleation center...

AI Technical Summary

Problems solved by technology

However, during the entire process of removing the gate oxide layer, the silicon substrate is not in contact with the chemical liquid, so the previously generated spherical defects cannot be removed during the removal of this oxide layer.

The ensuing problem is that the previously generated spherical defects will be transferred to the subsequent process layer accordingly, which will have a serious impact on the yield

[0004] According to the above analysis, it can be seen that the removal method of the gate oxide layer at the 28nm technology node is different from that at the 40nm technology node, resulting in spherical defects remaining on the substrate surface after the removal of the gate oxide layer. After dry etching the polysilicon gate, these defects will be transferred to the polysilicon gate layer and the polysilicon wire cutting layer, resulting in the failure of the corresponding pattern, and finally causing the device to fail hard, seriously affecting the device yield

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