Strength of Nanoscale Copper Connection Under Shear

摘要

Strength and shear modulus of several polycrystalline copper systems were calculated with the molecular dynamics method and effective-medium potential. Grain size varied between 2-10nm and systems were sheared beyond the yield point at room temperature. An inverse Hall-Petch behavior was seen: the strength decreased with decreasing grain size. Similar behavior was seen for the shear modulus. These were caused by the grain boundaries, which allow sliding and have low elastic constants. Comparison with tensile strength from another simulation shows that the Von Mises failure criterion holds quite well even at these length scales. To further study the properties of interconnections, copper-tantalum interface was studied with an embedded atom alloy model. Preliminary results show that the properties of the interface are very sensitive to its microstructure and failure may occur there.