Chemistry and morphology of Cr/BPDA-PDA interface formation

Abstract

X-ray photoelectron spectroscopy has been used to investigate the interaction between Cr and BPDA-PDA polyimide for Cr coverages up to 18 A. Detailed core level analysis reveals that the spectral changes induced by Cr deposition are a consequence of both the chemistry and the redistribution of reaction products in the overlayer. Two distinct N bonding configurations are readily resolved; one formed at lowest coverage remains localized at the buried interface, whereas the second becomes intermixed in the overlayer. Uniform overlayer growth is observed above - 3.5 A. The data for low Cr coverages are compared to molecular orbital calculations for two model bonding configurations. Agreement between theory and experiment for the C Is core level is better for a model compound with an O atom removed from the polymer backbone than for one where Cr is bound to a benzene ring. However, the quantitative differences suggest that a model should be considered where Cr interacts with carbonyl groups and additional reaction sites. © 1993, American Vacuum Society. All rights reserved.