MECHANISMS OF ADHESION ENHANCEMENT USING REACTIVE ION MIXING

Reactive (Si-28+ and Al-27+) and nonreactive (Ar-40+ and Kr-84+) ion mixing was performed on Ni, Cu, and Ni/Si films on polymeric and ceramic substrates. Nonreactive ion mixing gave little or no adhesion enhancement despite substantial interfacial mixing and substrate hardening. Reactive ion mixing produced significant adhesion enhancements (2-45 x). These adhesion enhancements were attributed to the formation of ion-induced chemical complexes that chemically attach the films and substrates. These interfacial complexes are formed most readily by reactive ions that are thermodynamically reactive with both film and substrate species and that are capable of forming mixed chemical bonds. Reactive intermediate layers and nonreactive ion mixing can also produce interfacial complexes and adhesion enhancement, but care must be taken to avoid selective reaction and the formation of inert interfacial compounds.