Argon entrapment in metal films by dc triode sputtering

Sputtered films of 12 elementary metals were analyzed for argon content by an rf spark−source mass−spectrographic method. All films were deposited using dc triode sputtering under similar conditions. Corrections in the data have been made to account for variations in target size and deposition rate. The experimental results are compared with sticking probabilities calculated using the Born−Mayer interatomic potentials; the agreement is fair except for elements having low atomic numbers, e.g., Cu and lower. The data confirm the role of reflected argon atoms in the entrapment mechanism at the substrate—as the atomic mass of the target material increases, the average energy of the reflected energetic argon atoms also increases, leading to the increased argon content in the film. The data also suggest that the entrapped argon content is dependent upon the atomic spacing of the film material.