The C49 to C54-TiSi₂ transformation in self-aligned silicide applications

Abstract

We show that when processing conditions closely mimic those used in the conventional self-aligned silicide process, the effective activation energy for the polymorphic phase transformation of orthorhombic base-centered (oC12) C49-TiSi2 to the low-resistivity orthorhombic face-centered (oF24) C54-TiSi2 phase is over 1 eV higher than previously reported literature values where a 1-step heat cycle was used. For C49-TiSi2 films formed at temperatures of 600 and 625°C on (100) single crystal silicon substrates, the activation energy was determined to be 5.6±0.3 and 5.7±0.13 eV, respectively, for the transformation of this phase into C54-TiSi2 in the temperature range of 625-700°C. The higher activation energy obtained with the simulation of the self-aligned silicide processing conditions suggests that the conventional processing may need to be modified for future semiconductor applications.