Mask assembly for interconnection layer structure and preparation method of interconnection layer

The application discloses a mask assembly for forming an interconnection layer structure and a preparation method of an interconnection layer. The mask assembly is located on a medium layer, and comprises an oxide mask layer, an amorphous carbon layer and a metal hard mask layer which are successively disposed on the medium layer. The preparation method comprises successively forming the medium layer and the mask assembly, which comprises the oxide mask layer, the amorphous carbon layer and the metal hard mask layer which are successively disposed on the medium layer, on a substrate, etching the mask assembly to form an opening, etching the medium layer exposed out of the opening, forming a through hole in the medium layer, and filling a metal material in the through hole to form a metal layer. Combination strength of the metal layer and the medium layer in the interconnection layer formed through preparation of the adopted mask assembly is improved, and then stability of the interconnection layer is improved.