Characterization of HfO _x N _y thin film formation by in-situ plasma enhanced atomic layer deposition using NH ₃ and N ₂ plasmas

The structural and electrical characteristics of in-situ nitrogen-incorporated plasma enhanced atomic layer deposition (PE-ALD) HfO _x N _y thin films using NH ₃ and N ₂ plasmas as reactants were comparatively studied. The HfO _x N _y test structures prepared using NH ₃ and N ₂ plasmas were analyzed by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and high resolution transmission electron microscopy (HR-TEM) to investigate the chemical composition, crystallinity, and cross-sectional layers including the interfacial layer, respectively. By utilizing NH ₃ and N ₂ plasmas, the nitrogen-incorporated HfO _x N _y thin films fabricated by in-situ PE-ALD showed a high dielectric constant and thermal stability, which suppresses the interfacial layer and increases the crystallization temperature. The high leakage current densities of the HfO _x N _y thin film test structures fabricated using NH ₃ and N ₂ plasmas caused by lowering the energy bandgap and band offset are related to the HfN bond ratio and dielectric constant.