Effect of Seed Layer on Grain Size of Electroplated Cu

Copper is widely used as the wires of semiconductor. The grain size of copper has been approved to influence its strength, ductility and conductivity. The larger the grain size, the less the grain boundary. Accordingly, the copper conductivity increases because grain boundary is the resistance of electronic transfer. Hence, the larger the grain size is, the better the copper conductivity will be. In this work, we attempt to produce thick copper film with large grain size by means of electroplating. We found that seed layers could influence the structure of electroplated copper. Hence, we employed various seed layer materials, such as titanium, copper. The cross-section of the electroplated copper was observed by optical microscope (OM), focused ion beam (FIB), scanning electron spectroscopy (SEM) and transmission electron microscope (TEM). The plating additives were characterized using potentiostatic.