Effects of Interface Structure on the Mechanical Properties and Deformation Mechanisms of Copper–Tantalum Interface via Molecular Dynamic Simulation

Through silicon via (TSV) is a core technology in 3-D integration. Interface failure is one of the most noted failure forms of TSV. The barrier layer Ta, which is between the media Cu and the insulating layer SiO2, is often neglected due to its small thickness. However, the Cu/Ta interface is prone to cracking and debonding, thus plays an important role in TSV interface reliability. In this work, the Cu/Ta interface models with different structures were established by molecular dynamics (MD) simulation method. Then tensile simulations were performed. The effects of interface structures on the interface mechanical properties and the deformation mechanisms were analyzed based on dislocations and crystal phase transitions. The critical strain energy release rate values of the rough and tilted interface were 17.21 and 13.66 J/m2, respectively. Both of them were larger than the perfect interface, whose value was 11.24 J/m2. While the interface void decreased the energy release rate significantly. When the void length increased from 4 to 16 nm, the energy release rate decreased almost monotonously from 6.06 to 1.46 J/m2. The Ta layer was more stable compared with the Cu layer. During the tensile process, dislocation reactions, phase transitions, and stress concentrations mainly occurred in the Cu layer. The cracks sprouted on the Cu layer and extended along the interface. The local plastic deformation of Cu layer around the void was the main factor affecting the tensile deformation behavior. The longer the void, the greater the local plastic deformation.