HIGH-RESOLUTION CROSS-SECTIONAL TRANSMISSION ELECTRON-MICROSCOPY OF THERMAL OXIDE-FILMS ON COPPER

The structure of thermal oxide films on copper has been investigated b y transmission electron microscopy of ultramicrotomed sections. Sectio ns of the copper substrate and its oxide film less than 10 nm thick an d suitable for high resolution examinations were prepared with negligi ble damage to the oxide film and the oxide/metal interface. Such exami nation revealed the mosaic structure of the oxide and the oxide/metal interface with atomic resolution. Further, oxidation rate differences between individual metal grains and the extents of paths for easy diff usion are revealed. For metal grains of low oxidation rate, the platel et oxide structure suggests that coherent or low angle boundaries sepa rating crystallites do not act as paths for easy diffusion. Conversely , where fine spherical oxide particles are present, incoherent boundar ies between particles offer many potential sites for easy transport.