Modeling Copper Plastic Deformation and Liner Viscoelastic Flow Effects on Performance and Reliability in Through Silicon Via (TSV) Fabrication Processes

Copper plastic deformation and liner viscoelastic flow effects on performance and reliability are studied for TSV-middle and backside TSV-last fabrication processes. Incremental plasticity model with nonlinear hardening and Maxwell viscoelasticity model are employed to characterize TSV copper and liner dielectrics material behaviors. The model parameters are chosen to match experimental data. It is found that both plastic deformation in copper and viscoelastic flow in dielectrics affect the trade-off between TSV keep-out-zone (KOZ) size and TSV extrusion. The backside TSV-last process generates less residual stresses and mobility changes in active silicon than the TSV-middle process, and avoids M1 metal resistance increase due to TSV extrusion at elevated process temperatures. The TSV plastic deformation and liner viscoelastic flow effects on residual stresses and reliability in M1 interconnects and dielectrics are also examined for two different M1 configurations.