Atomic Layer Deposition of TiN Films by Alternate Supply of Tetrakis(ethylmethylamino)-Titanium and Ammonia

Abstract

Atomic layer deposition (ALD) of amorphous TiN films on SiO₂ between 170°C and 210°C has been investigated by alternate supply of reactant sources, Ti[N(C₂H₅CH₃)₂]₄ [tetrakis(ethylmethylamino)titanium:TEMAT] and NH₃. Reactant sources were injected into the reactor in the following order:TEMAT vapor pulse, Ar gas pulse, NH₃ gas pulse and Ar gas pulse. Film thickness per cycle was saturated at around 1.6 monolayers (ML) per cycle with sufficient pulse times of reactant sources at 200°C. The results suggest that film thickness per cycle could exceed 1 ML/cycle in ALD, and are explained by the rechemisorption mechanism of the reactant sources. An ideal linear relationship between number of cycles and film thickness is confirmed. As a result of surface limited reactions of ALD, step coverage was excellent. Particles caused by the gas phase reactions between TEMAT and NH₃ were almost absent because TEMAT was segregated from NH₃ by the Ar pulse. In spite of relatively low substrate temperature, carbon impurity was incorporated below 4 at.%.