ABSTRACT
EARLY STAGES OF COPPER/POLYIM IDE INTERFACE FORM ATION
M. Kiene, T. Strunskus and F. Faupel
Technische Fakultat der CAU Kiel K aiserstr. 2 24143 Kiel, Germany
In this paper we use a multi-technique approach to characterize the initial stages of copper/polyimide interface formation. Copper was vapor-deposited onto fully cured PMDA-ODA polyimide (PI). Deposits from submonolayer thickness up to 1.6 nm were investigated with x-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and atomic force microscopy (AFM). Copper was found to form clusters growing with increasing coverage at the polymer surface, even at room temperature (RT) deposition. Annealing of the RT deposits up to 350 °C, still well below the glass transition temperature of PI, leads to significant reduction of the copper XPS signal and is attributed to further cluster growth, confirmed by TEM and preliminary AFM results. No major Cu diffusion into the polymer occurs under these conditions. This suggests that no significant diffusion is to be expected upon annealing continuous Cu films. Changes in the lineshapes and positions in the x-ray induced copper Auger spectra were attributed to cluster size effects indicating that these data cannot be taken as evidence for chemical bond formation at the Cu/PI interface.
