Electrochemical and Surface Spectroscopic Investigations of the Conductor/Insulator Interface

Composite materials fabricated from alternating layers of insulators and conductors play an important role in the computer electronics industry and other high technology areas. Inherent in the successful application of these types of materials is satisfactory adhesion between the insulator-conductor layers. This research has set out to probe the interaction between these dissimilar materials through the application of ultra-high vacuum (UHV) surface analysis techniques. Through the use of X-ray Photoelectron Spectroscopy (XPS), Auger Electron Spectroscopy (AES), Ion Scattering Spectrometry (ISS), and Secondary Ion Mass Spectrometry (SIMS) the opposing surfaces of the conductor/insulator interface have been analyzed. These analyses have looked at the chemical and physical state of these surface both before and after adhesion. Particular attention has been directed toward the effects of various treatments on the chemical state of the insulator surface and the resulting correlation with adhesion performance. Results have indicated that treatments removing surface carbon contamination from the polyimide polymer Kapton improve the adhesion between polymer and metal. The greatest improvement in adhesion is realized from plasma treatment of the polymer surface. XPS indicates such treatment results in chemical changes in the polymer surface from interaction with the nitrogen plasma. XPS and AES results have also indicated a correlation between the nature and the extent of surface oxide layers on the adhesion between metal and polymer. These analytical techniques have also been applied to the metal/insulator interface existing at the surface of a chemically modified electrode. This electrode, consisting of a layer of the semiconductor Sn02 applied to a substrate of aluminosilicate zeolites has also been investigated by electrochemical techniques. Results indicate that interaction between the layers has an impact on processes occurring on the electrode surface. Functioning of the electrode system in electrochemical applications suggests that the system has potential for applications in areas such as electrocatalysis, sensitization of electrode surfaces, and shape selective control of the outcome of electrochemical reactions.