Semiconductor bump, preparation method thereof and packaging structure

The invention provides a semiconductor bump, a preparation method thereof and a packaging structure. The preparation method comprises the steps of providing a substrate; forming an under bump metal layer on the substrate; performing a first composition process on the under bump metal layer to form a first metal functional layer on the under bump metal layer; and performing a second composition process on the under bump metal layer and the first metal functional layer to form a second metal functional layer covering the surface of the first metal functional layer. The first metal functional layer and the second metal functional layer covering the first metal functional layer are formed by two composition processes, the first metal functional layer can be prevented from being directly exposed in the air; therefore, the phenomenon of failure caused by oxidation, corrosion and the like of the first metal functional layer (such as copper and the like) in the air can be effectively avoided,the manufacturing yield o