Preparation method of metal fine structure

The invention provides a preparation method of a metal fine structure. The preparation method comprises the following steps: 1) forming a hard mask layer on a substrate; 2) forming a photoresist pattern on the hard mask layer; 3) etching the hard mask layer to form a groove pattern in the hard mask layer, and removing the photoresist pattern; 4) forming a metal layer in the groove pattern and on the surface of the hard mask layer; 5) performing planarization processing on the metal layer to enable the top surface of the metal layer in the groove pattern to be flush with the top surface of the hard mask layer so as to obtain a pattern metal layer in the groove pattern; 6) forming a protection pattern on the pattern metal layer; and 7) removing the hard mask layer through dry etching, and removing the protection pattern to obtain a pattern metal layer on the substrate. According to the invention, the problem that irregular burrs are easy to appear on the side wall and the surface of the metal pattern in the exi