A method of forming a solder bump on a substrate includes: forming a conductive layer(s) on the substrate having a surface on which an electrode pad is prepared; forming a resist layer on the conductive layer(s) having an opening over the electrode pad; forming a metal pillar in the opening of the resist layer, wherein the metal pillar includes a first conductive material; forming a space between sidewalls of the resist layer and the metal pillar; forming a metal barrier layer in the space and on a top surface of the metal pillar, the metal barrier layer including a second conductive material that is different from the first conductive material of the metal pillar; forming a solder layer on the metal barrier layer over the top surface of the metal pillar; removing the resist layer; removing the conductive layer(s); and forming the solder bump by reflowing the solder layer.