Thermal stability of TiSi₂ films on single crystal and polycrystalline silicon

The stability of selectively formed TiSi₂ films on single crystal and polycrystalline silicon layers at elevated process temperatures is reported. Extensive electrical and analytical studies were performed to understand the high-temperature stability of TiSi₂ films as a function of (i) substrate dopant concentration, (ii) titanium silicide thickness, (iii) silicide formation sequence, and (iv) silicide post-processing steps. It is shown that all four process variations have a profound influence on the thermal stability of TiSi₂ films. It is observed that titanium silicide films formed on single crystal silicon are stable at higher processing temperatures compared to those formed on polysilicon substrates under similar conditions. The degradation of high-temperature stability of TiSi₂ films on polycrystalline silicon can be related to increased number of defects and grain boundaries. It is shown that TiSi₂ films can be successfully used in silicon integrated circuit applications where the post-silicide processing temperatures do not exceed 1000 °C.