Etching method for improving surface defect of wafer

The present invention relates to the technical field of semiconductors, and particularly relates to an etching method for improving the surface defect of a wafer. The method comprises the following steps of step 1, providing an aluminum liner, preparing a composite structure provided with a contact hole on the aluminum liner, and covering a fluoropolymer layer on the upper surface of the composite structure and the sidewall of the contact hole, wherein the contact hole of the composite structure is exposed to the upper surface of the aluminum liner; step 2, subjecting the fluoropolymer layer covered on the sidewall of the contact hole to plasma etching; step 3, etching to remove the fluoropolymer layer covered on the upper surface of the composite structure; step 4, cleaning the exposed contact hole and the exposed composite structure. According to the technical scheme of the invention, the influence of residual polymers on the sidewall of the contact hole and on the upper surface of the composite structure on the aluminum liner can be eliminated. Therefore, the defect condition on the surface of the wafer can be improved.