Effects of electro-less Ni layer as barrier/seed layers for high reliable and low cost Cu TSV

Effects of electro-less Ni layer as barrier/seed layers were evaluated for high reliable and low cost Cu TSVs. To electrically characterize the effectiveness of a Ni layer as barrier/seed layers for TSV application, we fabricated the trench MOS capacitor with 5μm dia. and 50μm depth TSV array. Via holes were successfully filled by Cu electro-plating by using Ni seed layer. To characterize the blocking property of the Ni layer to Cu diffusion, Cu atoms were intentionally diffused from Cu TSV by annealing at 300°C and 400°C. X-ray spectrometer (EDX) and C-t analysis results shows that Cu atoms not diffuse into t h e Si substrate via the Ni layer even after annealing at 400°C. The Ni barrier layer has good blocking properties compared to a PVD barrier layer.