The invention provides a self-aligned multi-patterning method, which comprises the following steps of: forming a side wall layer on the side wall of a mandrel layer, forming a protective layer on the surface of a material layer to be etched, and exposing a part of a second side surface of the side wall layer and the top of the mandrel layer; removing part of the core shaft layer to
expose part of the first side surface of the side wall layer; carrying out
smoothing treatment on the exposed side wall layer; removing the core shaft layer and the protective layer; and
etching the to-be-etched material layer by taking the side wall layer as a
mask to form an
etching layer. According to the method, the morphology
asymmetry of the side wall is reduced through the protective layer, the loss of the to-be-etched material layer is protected in the process of removing the mandrel, the
asymmetry of the side wall structure is further reduced by
etching and correcting the top of the side wall layer, the
height difference between the to-be-etched material layer on the left and right sides of the side wall can be reduced in the process of removing the protective layer, and the yield of the to-be-etched material layer is improved. Therefore, the morphology and size uniformity of the etching layer is improved, and the device performance is improved. In addition, the CD correction material layer is formed on the etching layer, so that the morphology and the size of the etching layer are further optimized, and the performance of the device is further enhanced.