Excellent Improvement of Contact Resistivity and Thermal Stability for High Temperature Process After Silicidation of TiSi2 Through Ta Interlayer for Diffusion Barrier

Abstract

Titanium Silicide (TiSi2 is a primary contact material with low-resistance contact characteristics used in nanodevices. However, the rapid scaling trend requires further improvement to achieve both high thermal stability and low contact resistivity. Herein, a method for simultaneously improving the contact resistivity and thermal stability of the TiSi2 /Si interface is proposed by inserting a Ta interlayer into Ti/p-Si. The Ta-interlayered TiSi2 (Ta IL TiSi2 ) achieves an improved contact resistivity by approximately 7.9 times compared to that without the Ta interlayer. This remarkable improvement is due to the smooth contact morphology resulting from the suppressed excess diffusion of Ti and Si and dopant segregation at the TiSi2/Si interface. Particularly, because additional reaction during post annealing is minimized by the Ta interlayer, Ta IL TiSi2 shows a low sheet resistance of 3.71 S-2/? even after post annealing at 600 C-? & 30 min, which is much lower than the conventional TiSi2 scheme under the same annealing conditions. These results are expected to provide insights into state-of-the-art CMOS-based devices that require both low contact resistivity and better thermal margins.