TSV Formation Using a Direct CU Electroplating on Electroless Plated Barrier Layer with a Low Resistivity

The demand for a low-cost metal filling technology to TSVs of 3D integration is increasing. In this situation, we studied a direct electroplating of Cu on an electroless plated (ELP) Co-alloy diffusion barriers formed in TSVs with a high aspect ratio. This technology enables a reduction of process steps and fabrication cost. It was shown that CoMn barrier had the lowest electrical resistivity among the Co-alloy barriers. We studied electroplated Cu filling in TSV hole by changing additive conditions on ELP barriers to obtain better Cu filling properties in TSVs. We successfully observed excellent Cu filling by the choice of Co alloy ELP barrier and the Cu plating bath composition for TSVs with a small diameter around 1μm,