Impact of atomic-layer-deposited TiN on the gate oxide quality of W/TiN/SiO2/Si metal-oxide-semiconductor structures

We demonstrate the impact of atomic-layer-deposited TiN gate on the characteristics of W/TiN/SiO2/p-Si metal-oxide-semiconductor (MOS) systems. Damage-free gate oxide quality was attained with atomic-layer-deposition (ALD)-TiN as manifested by an excellent interface trap density (D-it) as low as similar to4x10(10) eV(-1) cm(-2) near the Si midgap. ALD-TiN improved the D-it level of MOS systems on both thin SiO2 and high-permittivity (high-k) gate dielectrics. The leakage current of a MOS capacitor gated with ALD-TiN is remarkably lower than that with sputter-deposited TiN and poly-Si gate at the similar capacitance equivalent thickness (CET). Less chlorine content in ALD-TiN films appears to be pivotal in minimizing the CET increase against postmetal anneal and improving gate oxide reliability, paving a way for the direct metal gate process. (C) 2002 American Institute of Physics.