Semiconductor structure and preparation method thereof

The invention relates to a semiconductor structure and a preparation method thereof. The preparation method of the semiconductor structure comprises the following steps: providing a substrate, and forming a plurality of contact bonding pads on the substrate; depositing a dielectric layer on the substrate, filling gaps between the contact bonding pads with the dielectric layer, and covering the contact bonding pads; executing a plasma etching process to etch the dielectric layer until the contact bonding pad is exposed; etching gas used in the plasma etching process comprises oxygen-free etching gas. According to the preparation method, metal oxide can be prevented from being formed on the contact bonding pad, conductive metal particles or metal compounds are prevented from remaining on the surfaces of the contact bonding pad and the adjacent dielectric layer, surface damage of the contact bonding pad can be eliminated, the electrical performance of the semiconductor structure is ensured, and the service life