Preparation method of dual damascene structure

The invention discloses a preparation method of a dual damascene structure, and the preparation method comprises the steps: providing a semiconductor substrate, and sequentially forming a first dielectric layer and an etching barrier layer above the semiconductor substrate; and etching the etching barrier layer to form a first opening exposing the first dielectric layer in the etching barrier layer. And forming a second dielectric layer on the surface of the etched etching barrier layer, and filling the first opening with the second dielectric layer. And etching the second dielectric layer to form a groove at the position of the second dielectric layer corresponding to the first opening, exposing the etching barrier layer and the first opening from the bottom wall of the groove at the moment, and continuously etching the first dielectric layer based on the first opening to form a through hole in the first dielectric layer. The whole structure has a small dielectric constant, and the grooves and the through ho