Low-Resistivity Titanium Nitride Thin Films Fabricated by Atomic Layer Deposition with TiCl4 and Metal–Organic Precursors in Horizontal Vias

The resistivity of halogen-free atomic layer deposition (ALD) TiN thin films was decreased to 220 μΩ cm by combining the use of a high-thermal stability nonhalogenated Ti precursor with a highly reactive nitrogen source, anhydrous hydrazine (N2H4). TDMAT [tetrakis (dimethyl-amino)titanium], TDEAT [tetrakis(diethylamido)titanium], and TEMATi [tetrakis (ethylmethyl-amido)titanium] were compared to TiCl4 as precursors for ALD TiN using N2H4 as a coreactant. By minimizing the pulse length of the Ti-source precursor and optimizing the deposition temperature, the resistivity of TiN thin films deposited using these precursors was reduced to 400 μΩ cm for TDMAT (at 350 °C), 300 μΩ cm TDEAT (at 400 °C), and 220 μΩ cm for TEMATi (at 425 °C) compared to 80 μΩ cm for TiCl4 (at 500 °C). The data are consistent with the lowest resistivity for halogen-free ALD corresponding to the organic precursor with the highest thermal stability, thereby allowing maximum ALD temperature. After optimization, TiN thin films were grown in horizontal vias, illustrating conformal and uniform TiN using both TiCl4 and TEMATi in horizontal vias in patterned substrates.