An electrodeposition composition comprising: (a) a source of copper ions; (b) an acid; (c) a suppressor; and (d) a leveler, wherein the leveler comprises a quaternized dipyridyl compound prepared by reacting a dipyridyl compound with a difunctional alkylating agent or a quaternized poly(epihalohydrin). The electrodeposition composition can be used in a process for forming a copper feature over a semiconductor substrate in wafer level packaging to electrodeposit a copper bump or pillar on an underbump structure of a semiconductor assembly.