E.G. Colgan, K.P. Rodbell, et al.
Journal of Applied Physics
The copper concentration in aluminum-copper alloys can be altered by ion bombardment during film deposition. We have measured the sputtering yields of aluminum and copper in Al-Cu alloys as a function of the Cu concentration (5-13 at. %) and the angle of ion incidence (0°-40° from normal). During deposition, the films were partially resputtered by 500 eV Ar+ ion bombardment from a Kaufman ion source. We found that the Cu sputtering yield decreases by up to a factor of 10 in the alloy, relative to elemental Cu. The Al sputtering yield remains close to the elemental value. The net effect is a strong preferential sputtering of Al relative to Cu, which enhances the Cu concentration in an ion-bombarded film. The Al/Cu sputtering yield ratio for normal incidence ion bombardment ranges from 3 to 5 as a function of Cu concentration. This ratio decreases with increasing angle of incidence to as low as 2 for 40° incident ions. However, since a higher fraction of the film is resputtered from a sloping surface, a higher Cu concentration is found on a sloping surface relative to a flat surface. These results show that the film composition will vary as a function of the surface topography.
E.G. Colgan, K.P. Rodbell, et al.
Journal of Applied Physics
C. Cabral Jr., L. Clevenger, et al.
MRS Fall Meeting 1996
L. Clevenger, Q.Z. Hong, et al.
MRS Proceedings 1993
J.M.E. Harper, J.J. Cuomo, et al.
Applied Physics Letters