PURPOSE: UBM etching methods is provided to form a metal bump reducing under cut in UBM(Under-Bump Metallurgy). CONSTITUTION: A substrate(10) is provided. An UBM layer including a barrier(40) in a substrate and also includes a seed layer in the barrier. The first part of an UBM layer comprises the barrier part and the seed layer part. A metal bump(50) is formed on the second part of the UBM layer. Wet etching is performed by removing the seed layer partly. Dry etching is performed to remove the barrier part.
