Investigation on Thermal Release Behavior of Helium-Charged Copper Films by DC Magnetron Sputtering

Helium atoms are introduced into Cu films at room temperature by direct current (DC) magnetron sputtering in a He/Ar mixed atmosphere. The doped helium atoms are distributed evenly in the film and the content can be easily controlled by changing the process parameters. The structure of Cu films with trapped helium was investigated by X-ray diffraction (XRD) technology. With increasing helium irradiation flux, the lattice spacing and width of diffraction peaks increased due to helium effects, corresponding to the increase of finite and infinite size defects in the film. The shape of thermal desorption spectrum (TDS) and the number of peaks strongly depended on the amount of helium introduced into Cu. With increase of helium content, helium release temperature decreases. At the same amount of helium, the peak temperature became higher with increase of heating rate and from this we can obtain a picture which could calculate the activation energy of helium desorption.