Sintering of sputtered copper nanoparticles on (001)copper substrates

The sintering of sputtered copper nanoparticles with a thin film copper substrate has been studied in real time using a novel in-situ UHV TEM. Particles were generated by de sputtering in argon and transferred directly into the microscope along a connecting tube. The particles were deposited onto a clean(001) copper substrate of thickness 40nm. As-deposited particles assume a random orientation on the copper substrate as evidenced by electron diffraction patterns. Upon annealing, however, the particles were observed to reorient and assume the orientation of the substrate. Reorientation of individual, isolated particles occurred at similar to 200 degrees C, primarily by grain-boundary motion and not by surface diffusion.