FORMATION OF HIGH ADHESIVE AND PURE PT LAYERS ON TIO2

The formation of a high adhesive noble metal layer on an oxide layer has been investigated in the Pt/(Ti)/TiO2/SiO2/Si system, prepared in a vacuum evaporation apparatus. The thermosonic ball bonding test and the conventional pull test were successively applied to the evaluation of adhesion. The Ti inserted layer between the Pt and the TiO2 layer was found to improve the adhesion. A Ti layer of approximately 10 nm was found to be necessary for stronger adhesion. Auger electron spectroscopy (AES) depth profile results showed that a part of the Ti atoms in the inserted layer were segregated to the Pt surface from the interface by annealing at 1373 K for 30 min, while the rest of Ti atoms in the inserted layer remained and acted as a "glue" at the interface between the Pt and the TiO2 layer. It should be noted that Ti could not be detected in the Pt layer within the AES detection limits. Scanning electron microscope and energy dispersive x-ray spectroscopy observations showed that Ti diffusion occurred through the grain boundaries of the Pt layer and Ti atoms appeared at surface grain boundaries on top of the Pt layer.