A semiconductor structure includes a semiconductor device (100), a conductive pad (102) on the semiconductor device (100), and a Ag 1-x Y x alloy bump (101) over the conductive pad (102). The Y of the Ag 1-x Y x bump (101) comprises metals forming complete solid solution with Ag at arbitrary weight percentage (Au and/or Pd), and the x of the Ag 1-x Y x alloy bump (101) is in a range of from about 0.005 to about 0.25. A difference between standard deviation and mean value of a grain size distribution of the Ag 1-x Y x alloy bump (101) is in a range of from about 0.2 µm to about 0.4 µm. An average grain size of the Ag 1-x Y x alloy bump (101) on a longitudinal cross sectional plane is in a range of from about 0.5 µm to about 1.5 µm. The alloy bump (101) is formed by electroplating.