Optical spectroscopic study of the SiN/HfO_2 interfacial formation during rf sputtering of HfO_2

摘要

High-k stacks formed by chemical-vapor-deposited SiN and high-pressure sputtered HfO_2 in either O_2 or Ar atmosphere have been studied. The introduction of a SiN layer is proposed to prevent the uncontrollable SiO_2 growth while sputtering. The formation of Si-O bonds after the sputtering of the HfO_2 film in O_2 atmosphere was observed by infrared spectroscopy. Optical diagnosis of the plasma demonstrated a high density of O radicals in the system when working with O_2. The small radius and high reactivity of these O radicals are the source of the SiN oxidation. However, the structure of the SiN film is preserved during Ar sputtering.