Laser-induced thermo-compression bonding for Cu–Au heterogeneous nanojoining

Surface tension-induced shrinkage of heterogeneously bonded interfaces is a key factor in limiting the performance of nanostructures. Herein, we demonstrate a laser-induced thermo-compression bonding technology to suppress surface tension-induced shrinkage of Cu–Au bonded interface. A focused laser beam is used to apply localized heating and scattering force to the exposed Cu nanowire. The laser-induced scattering force and the heating can be adjusted by regulating the exposure intensity. When the ratio of scattering forces to the gravity of the exposed nanowire reaches 3.6 × 10 3 , the molten Cu nanowire is compressed into flattened shape rather than shrinking into nanosphere by the surface tension. As a result, the Cu–Au bonding interface is broadened fourfold by the scattering force, leading to a reduction in contact resistance of approximately 56%. This noncontact thermo-compression bonding technology provides significant possibilities for the interconnect packaging and integration of nanodevices. A laser-induced thermocompression bonding technique is demonstrated. Cu nanowires with diameters of around 200 nm are successfully bonded to Au pad using laser. Pressure generated by laser scattering effectively suppresses shrinkage of the joining interface resulting from surface tension. Laser-induced thermocompression effect effectively enlarges the Cu–Au nanojoining interface. Expanded Cu–Au bonding interface effectively reduces interface contact resistance.