Bump structure having a reinforcement member

A manufacturing method of a bump structure having a reinforcement member is disclosed. First, a substrate including pads and a passivation layer is provided. The passivation layer has first openings, and each first opening exposes a portion of the corresponding pad respectively. Next, an under ball metal (UBM) material layer is formed on the substrate to cover the passivation layer and the pads exposed by the passivation layer. Bumps are formed on the UBM material layer and the lower surface of each bump is smaller than that of the opening. Each reinforcement member formed on the UBM material layer around each bump contacts with each bump, and the material of the reinforcement member is a polymer. The UBM material layer is patterned to form UBM layers and the lower surface of each UBM layer is larger than that of each corresponding opening. Hence, the bump has a planar upper surface.