Multiple species sputtering for improved bottom coverage and improved sputter rate

摘要

An improved sputtering process increases the perpendicularity of the sputtered flux to the target surface by bombarding the target with both low and high mass ions, with low mass ions predominating, packing the target with both low and high mass implanted ions, and causing target atoms ejected as a result of high mass incident ions to have a higher probability of perpendicular or near perpendicular ejection. An alternative improved sputtering process bombards the target with both low and high mass ions, with high mass ions predominating, resulting in a higher sputter rate than achievable with either the high or low mass species alone. Including in either process as the high or the low mass species a species having a lower ionization energy than a standard species allows a reduced pressure plasma, resulting in less scattering of the sputtered flux. A low ionization energy species may also be employed to assist in striking a plasma before sputtering by a single species during deposition.