The formation of titanium silicides by rapid thermal processing: an XRD and AES study

X-ray diffraction and Auger depth profiling were performed to investigate the reaction of Ti thin films with single crystalline (100) Si by rapid thermal annealing under N₂ and Ar. Within a few seconds titanium silicides are formed at temperatures between 620 and 700°C. The silicides consist of TiSi₂, TiSi and titanium-rich subsilicides like Ti₅Si₄ and Ti₅Si₃. TiSi₂ is the metastable, poorly-conducting C49 modification. Growth of this phase takes place near the substrate interface, and the Ti-rich silicides are situated closer to the surface. The crystallites of the different silicides exhibit a strong texture. Annealing under N₂ leads to the formation of titanium nitrides TiN_x near the surface and subsequent growth towards the suicide during prolonged thermal treatments. When the silicide and nitride reaction fronts coalesce the available Ti is consumed for these reactions. Further silicide growth can occur only via complex phase transformations.