Reactive sputtering for highly oriented HfN film growth on Si (100) substrate

Highly oriented cubic (100) HfN films were grown on Si (100) substrates by direct current magnetron reactive sputtering of a metallic Hf target in an Ar/N-2 gas environment. The influence of N-2 flow ratio on the (100) preferred orientation and crystallinity of the HfN films is investigated. X-ray diffraction shows that not only HEN but also orthorhombic HfSi2 forms in the sputtered films. Increasing the N-2 flow ratio is unfavorable for the formation of HfSi2 while the deposition rate of HfN is decreased. X-ray diffraction and cross-sectional scanning transmission electron microscopy (STEM) reveal that epitaxial orthorhombic HfSi2 can form on the Si substrate, and (100) HfN is in epitaxy with the epitaxial HfSi2. As a result, a (100) oriented HfN film can grow on Si. The epitaxial relationships are shown to be HfN (100)[01 (1) over bar] // HfSi2 (020)[001] // Si (100)[01 (1) over bar] and HfN (100)[01 (1) over bar] // HfSi2 (020)[100] // Si (100)[01 (1) over bar]. Atomically resolved STEM images also show the bonding characteristics across the HfN/HfSi2 and HfSi2/Si interfaces.