Characterization of TiSi2/TiN thin films on Si by HREM

Abstract

Titanium Nitride is commonly used as a diffusion barrier layer in Al-Si contacts. There are different techniques employed to deposit TiN layers on silicon, out of them thermally grown and reactively sputtered are most common. Reactive sputtering is a one step process and is favoured for manufacturing. The orientation of TiN thin films controls the orientation of Al films deposited. As sputtered films has random orientation hence the overlying Al films is randomly oriented as well. In order to achieve higher electromagnetic resistance, Al films should be well oriented. Thermally grown TiN thin films are highly oriented but their thickness is limited to about 20nm. We have used HREM and micro-analytical techniques to analyze the thickness, structure and compositions of various layers formed during thermal growth of TiN layers deposited under different conditions.Thermally grown Ti films on Si <100> wafers of varying thicknesses were deposited and annealed in NH3 atmosphere at different temperatures and times. Second layer of titanium was deposited and processed on some of the samples (double process) in order to increase the thickness of TiN layer.