Atomic layer deposition of Ruthenium became essential for sub-20 nm DRAM. Together with interconnects, both emerged as the bottleneck for the future technology nodes posing stringent requirements on the deposition technique. Here, thermal ALD of Ru thin films from EBECHRu (ethyl-benzene ethyl-1,4-cyclohexadiene ruthenium) and O2 are grown on prototype substrates (SiO2 and TiN) relevant from the application perspective. Through quadrupole mass spectrometry the pivotal role of the O2 reactant during metal growth will be explored. The Ru film characteristics are predominantly set by the nucleation and growth behavior. Generally in ALD, the steady state growth of Ru is independent of the initial substrate. Here will be argued an interaction between the growing metal and the underlying transition-metal rich substrate TiN can be forced throughout the full growth phase clearly enhancing the growth rate per cycle to more than double compared to conventional SiO2. The growth mechanism is denoted as surfactant mediated growth, and will be portrayed through a highly surface sensitive technique (ToF-SIMS). Surfactants target vast physical and electric Ru film characteristics, e.g. incubation, film texture, and grain size. Low resistive films with lateral grain sizes up to ~30 nm have been deposited on oxide, and start to match the conventional interconnect metal Cu below the 10 nm film thickness.
|Date of Award||30 Sep 2014|
|Supervisor||M. Popovici (Supervisor 1), Ageeth A. Bol (Supervisor 2) & C. Adelmann (External coach)|