Formation method of semiconductor device

The invention provides a method for forming a semiconductor device, which comprises the following steps of: providing a substrate, and forming an initial connection layer on the substrate; flattening the initial connection layer, and forming a connection layer on the substrate; performing heat treatment on the surface of the connecting layer; residues on the surface of the connecting layer can be removed by performing heat treatment on the surface of the connecting layer; the surface cleanliness of the connecting layer is improved, so that an upper conducting layer is subsequently formed on the connecting layer, it is guaranteed that the upper conducting layer has a good forming face in the forming process, the connecting quality between the upper conducting layer and the connecting layer is improved, and the phenomenon that the upper conducting layer protrudes or is not uniform in the forming process is reduced; the forming quality of the upper conductive layer is improved, and the performance of the finally