This study examines the effects of a thin Ta interlayer on the formation of TiSi2 on Si(111) substrate. The Ta interlayer was introduced by depositing Ta and Ti films sequentially on an atomically clean Si(111) substrate in an ultrahigh vacuum (UHV) system. Samples of 100 Å Ti with 5 and 10 A Ta interlayers were compared to similar structures without an interlayer. After deposition, the substrates were annealed for 10 min, in situ, at temperatures between 500 and 750°C in 50°C increments. The TiSi2 formation with and without the Ta interlayer was analyzed with an X-ray diffractometer, Auger electron spectroscopy (AES), Scanning electron microscopy (SEM), transmission electron microscopy (TEM), and a four-point probe. The AES analysis data showed a 1:2 ratio of Ti:Si in the Ti-silicide layer and indicated that the Ta layer remained at the interface between TiSi2 and the Si(1111) substrate. The C 49-C 54 TiSi2 phase transition temperature was lowered by ∼200°C. The C 49-C 54 TiSi2 phase transition temperature was 550∼C for the samples with a Ta interlayer and was 750°C for the samples with no Ta interlayer. The sheet resistance of the Ta interlayered Ti suicide showed lower values of resistivity at low temperatures which indicated the change in phase transition temperature. The C 54 TiSi2 displayed different crystal orientation when the Ta interlayer was employed. The SEM and TEM micrographs showed that the TiSi2 with a Ta interlayer significantly suppressed the tendency to islanding and surface agglomeration.
ASJC Scopus subject areas
- General Physics and Astronomy