| Popis: |
Through chip electrodes with high aspect ratios offer the shortest interconnection and reduce signal delay. In this work, filling vias with higher aspect ratio copper, 10 μm in square and 70 μm in depth, used for through chip electrodes was investigated, using a commercially-available bath and a specially-designed one. We used the commercially-available bath containing CuSO 4 .5H 2 O and H 2 SO 4 for basic bath, and PEG (polyethylene glycol), JGB (Janus Green B), SPS (Bis (3-sulfopropyl) disulfide) and HCl as additives. With this commercially-available bath of optimized composition, electroplating time was shortened to 3.5 hr by adopting two-step electroplating method, i.e. application of initial lower current density level of 2 mA/cm 2 for 2 hr and final higher current density level of 3 mA/cm 2 for 1.5 hr. Furthermore, electroplating time of 2.5 hr was achieved with the use of specially-designed bath: (SPS, SPR B, LEV A) = ( 2 ppm, 2 ppm, 0.5 ppm). |
