Ion mixing of the interface between TiNi films and glass substrates

Abstract

Atomic mixing between TiNi metallic thin films and glass substrates, silica glass and borosilicate glass was induced by argon ion bombardment and investigated by means of Auger electron spectroscopy. 150 keV argon ion bombardment was carried out at room temperature to doses of 5x10 16 and 1x10 17 ions cm -2. The Auger analysis demonstrated that significant intermixing occured at the TiNi-glass interface after argon ion bombardment and that the degree of atomic mixing varied, depending on the species of the constituent atoms. It was found that the titanium atoms were always transported deeper into the glass substrates than nickel atoms, and silicon atoms diffused into the TiNi overlayer more than oxygen atoms. The light boron atoms in borosilicate glass were found to diffuse least during argon ion bombardment. It was suggested that some metal silicides and oxides were formed in the reacted interface regions. Indentation-fracture tests revealed that the adhesion between the TiNi films and the glass substrates was improved substantially by argon ion mixing. The atomic mixing of each constituent atom was discussed qualitatively using a model of isotropic cascade mixing. The improved adhesion of the interface was thought to result from the interface mixing and the resultant formation of metal silicides and titanium oxides of various valence states in the interface region.