PT TI SIO2 SI SUBSTRATES

Pt/Ti/SiO2/Si structures have been studied to investigate the structur al, chemical, and microstructural changes that occur during annealing. Grain growth of the as-deposited Pt columns was observed after anneal ing at 650 degrees C, and extensive changes in the Pt microstructure w ere apparent following a 750 degrees C anneal for 20 min. In addition, two types of defects were identified on the surfaces of annealed subs trates. Defect formation was retarded when the surface was covered wit h a ferroelectric film. Concurrent with the annealing-induced Pt micro structure changes, Ti from the adhesion layer between the Pt and the S iO2 migrated into the Pt layer and oxidized. It was shown with spectro scopic ellipsometry and Auger electron spectroscopy that for long anne aling times, the titanium oxide layer can reach the Pt surface. Conseq uently, at the processing temperatures utilized in preparing many ferr oelectric thin films, the substrate is not completely inert or immobil e. The changes associated with Ti migration could be especially proble matic in techniques that require the substrate to be heated prior to f ilm deposition.