Aluminum deposition on polyimides: The effect of in situ ion bombardment

The chemistry of the Al polyimide interface is examined by x‐ray photoelectron spectroscopy sputter profiling. Al deposited on polyimide films without an in situ Ar backsputter shows a clearly defined 50‐Å Al₂O₃ 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 Al 2p transition. There is a clear separation of the Al/Al₂O₃/polyimide layers in the sputter profiles. Deposition of Al on polyimide surfaces after Argon backsputtering produces a diffuse Al/polyimide interface with no Al₂O₃ present. There is evidence in the Al 2p spectra for Al–C or Al–O–C type bonds, while the C 1s spectrum clearly has a metal carbide component. Increased adhesion of Al to polyimide surfaces with Ar backsputtering may be due to the differences in chemistry observed in these two instances.