PIN-PULL ADHESION MEASUREMENTS OF COPPER-FILMS ON ION-BOMBARDED ALUMINA

Copper films were deposited by evaporation onto aluminal substrates that had been sputtered to various doses with 500 eV ions. The adhesion strength of the films was measured with a pull-type adhesion tester. The adhesion of Cu to solvent-cleaned surfaces was low, but argon ion sputter cleaning produced adhesion near 80 MPa, and adhesion after oxygen ion bombardment was even better. Exposing the alumina to argon-oxygen plasma discharge (approximate to 40 eV ions) from the Kaufman-type ion source increased the adhesion beyond approximate to 55 MPa. The applicability of Weibull statistical analysis to the distribution of pull test data for solvent-cleaned rough alumina was investigated. A good fit of the data to the Weibull expression was observed, with zero apparent threshold strength and a low Weibull modulus of approximate to 2.9.