Morphological Changes, He Desorption Behaviors, and He Bubble Evolution of He-charged Cu Films Prepared by DC Magnetron Sputtering During Annealing

He-charged Cu films were prepared at room temperature by direct current (DC) magnetron sputtering in a He/Ar mixed atmosphere. Morphological changes, He desorption behaviors, and He bubble evolution of He-charged Cu films after the annealing treatments at different temperatures were investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), respectively. The results of SEM revealed that some blisters and pinholes were found at the surface and cross-section of He-charged Cu films after the annealing. The results of TDS profiles suggested that different kinds of He could be introduced into Cu films by a magnetron sputtering method. TEM analysis suggested that nano-sized He bubbles could be formed in as-deposited Cu films, and He bubble size increased with the increasing annealing temperature. The growth mechanism of helium bubbles in Cu film was suggested to originate from the migration and coalescence (MC) mechanism.