Temperature dependence of the sticking coefficient in atomic layer deposition

The temperature dependence of the sticking coefficient (SC) of precursor molecules used in atomic layer deposition (ALD) was investigated. Tetrakis(ethylmethylamino)hafnium (TEMAHf) and Pentamethylcyclopentadienyltitan-trimethoxid (Cp*Ti(OMe)3) were used in combination with ozone to deposit hafnium dioxide and titanium dioxide films at different substrate temperatures. The SC of TEMAHf was determined at 180, 230, and 270 °C. The SC of TEMAHf depends exponentially on the substrate temperature. The activation energy and the pre-exponential factor were obtained for this ALD process. The SC of Cp*Ti(OMe)3 was determined at 270 °C. A possible explanation for the small SC of Cp*Ti(OMe)3 could be the reduced symmetry of the precursor molecule. Therefore, symmetric precursor molecules and high process temperatures appear beneficial for efficient ALD processes.