Reduction of TSV Pumping

The mismatch in thermal expansion coefficient (TEC) between copper and silicon causes serious problems in three-dimensional (3D) packaging. The common problem is TSV pumping when TSV is exposed to high temperature (400oC-600oC) during the wiring process. The copper pumping destroys wiring above TSV and leads to the failure of electronic devices. Other problem is the area on silicon around the TSV where the transistors cannot be formed due to stress caused by copper when annealing. With our low TEC additive (additive A), copper pumping height in 5× 20 μm p-TEOS TSV was reduced to 0.5 μm from 2.0 μm in case of conventional copper. We also investigated the effect of polyimide which is used as liner layer in the TSV on copper pumping reduction. The first screening result showed that the pumping height of conventional copper in polyimide TSV was only 0.8 μm., compared to 2.0 μm p-TEOS TSV and 1.2 μm O3-TEOS TSV.