Copper/ polyimide interaction: A local spin density study

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Abstract
The interactions between a copper atom and various model molecules, phthalimide (PIM), PMDA and amino phenol (PAP), which represent well the functionalities of the polyimide PMDA-ODA, are studied using the quantum chemical local density functional (LDF) method. We found that Cu interacts preferentially with the PMDA's model molecules and less with the PAP. For the Cu/PIM and Cu/PMDA systems, four interaction sites have been investigated: the nitrogen atom, the phenyl ring, the five-membered imide ring, and the carbonyl group. The last site (C=O) was found to be the favored interaction site for Cu. The corresponding bond dissociation energy is 1.20 eV in both Cu/PMDA and Cu/PIM. In the case of Cu/PAP, the nitrogen and C-O bond sites have been investigated. The corresponding total energies differ only by 0.05 eV. The binding energy for Cu/PAP is 0.65 eV. Thus, the PMDA carbonyl group is the favored site for bonding with a Cu atom. As shown in our previous study on Cr/PMDA, Cr is more reactive than Cu and also interacts with the C=O group. Our results are in agreement with X-ray Photoelectron Spectroscopy (XPS) and Infra-Red Reflection Absorption Spectroscopy (IRRAS) measurements carried out on Cu/polyimide interfaces.