Growth, physical properties, and adhesion of copper-polyphenylquinoxaline interfaces

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Abstract
Monochromatized x-ray photoelectron spectroscopy, contact angle measurements, and peeling tests have been used to investigate the physicochemical surface properties of polyphenylquinoxaline (PPQ) and of copper-PPQ interfaces. The surface composition and oxygen content of a polymer that was deliberately oxidized by ultraviolet exposure in air were determined, and monitored during the anneal (up to 400 °C) of this thermostable polymer. Subsequent copper deposition in the monolayer range and film growth is characterized by small cluster formation, before percolation into a conducting metallic layer. Further anneal of the Cu-PPQ interface is seen to promote diffusion of Cu into the polymer, and to catalytically degrade the interface by oxidizing the polymer. These observations are correlated with peeling test measurements on the same Cu-PPQ interfaces: UV treatment combined with an anneal process are shown to be deleterious to the mechanical properties of the interface.