Semiconductor structure and preparation method thereof

The invention provides a semiconductor structure and a preparation method thereof. According to the preparation method provided by the invention, the groove can be repaired firstly, so that the uneven inner side surface of the groove can be flattened, and the problem that the etching rates of the side wall surfaces of the groove in different areas are different when an optimized HCL polishing process is subsequently carried out due to the uneven defect of the groove is avoided; according to the method, the uniformity of the etching rate of the optimized HCL polishing process is guaranteed, the problems that the morphology of the groove is deformed and the quality of the formed embedded epitaxial layer is poor are solved, and the optimized HCL polishing process can be subjected to gas phase corrosion in a low-temperature environment, so that the influence of a high-temperature environment on the morphology deformation of the groove is avoided, and the quality of the embedded epitaxial layer is improved. And an