Integral Formation of Circuit and Bump by Plating Process without Chemical Mechanical Polishing (CMP)

摘要

In order to form a bump on an existing circuit, after forming a plating resist having an open portion that would become a bump on the circuit, plating is performed with a thickness equal to or greater than the thickness of the resist to form a mushroom-shaped bump. These mushroom-shaped bumps are polished by CMP, whereby it is possible to form bumps having a uniform height and a flat top. However, this kind of process is complicated and advanced techniques are required. Furthermore, as circuits and bumps are become more miniaturized, it is also difficult to achieve the necessary adhesion strength between the circuit and the bumps as well as the circuit and the materials. By using the formation method that we examined, we were able to form circuit-integrated bumps of uniform height and flat top without using CMP.