Aluminum Deposition on Polyimides: The Effect of in situ Ion Bombardment.

The chemistry of the Al polyimide interface is examined by XPS sputter profiling. Al deposited polyimide films without an in situ Ar backsputter shows a clearly defined 50angstroms Al sub 2 O sub 3 layer just prior to the polyimide. This layer is identified by the O/Al atom ratio at 1.5, and the binding energy of the Al2p transition. The C1s spectra are similar to those of ion bombarded polyimide, with no unusual features. There is also a clear separation of the Al/Al sub 2 O sub 3 /polyimide layers in the sputter profiles. Deposition of Al on polyimide surfaces after Argon backsputtering produces a diffuse Al/polyimide interface with no Al sub 2 O sub 3 present. There is evidence in the Al2p spectra for Al-C or Al-O-C type bonds, while the C1s spectrum clearly has a metal carbide component. Increased adhesion to Al to polyimide surfaces with Ar backsputtering may be due to the differences in chemistry observed in these two instances.