Low Temperature Plasma Enhanced Atomic Layer Deposition of Conducting Zirconium Nitride: In-situ growth characterization, recipe development, and the sources of oxygen contamination in films

• Author / Creator

  Muneshwar, Triratna P

• Atomic layer deposition (ALD) enables uniform and conformal deposition of sub-nanometer thick films over large substrate area, hence is the most suitable technique for deposition of critical features in modern semiconductor fabrication. Compared to other transition metal nitrides, reported studies on zirconium nitride (ZrN) ALD are scarce. Moreover ALD of conducting ZrN is relevant for numerous applications in advanced semiconductor devices. Plasma enhanced ALD (PEALD) ZrN thin films using tetrakis-dimethylamido zirconium (TDMAZr) and forming gas (5% H2, 95% N2) reactant plasma were grown on p-type Si (111) and thermal SiO2 substrates at temperatures in the range of 100 °C - 350 °C. The ZrN PEALD growth was characterized from dynamic in-situ spectroscopic ellipsometry (d-iSE) measurements performed in real-time during film growth. A procedure was developed to interpret and analyze d-iSE data accounting for partial surface monolayer growth per ALD cycle. The optimum process parameters for self-limiting ZrN PEALD growth were determined from experiments designed on the basis of self-limiting ALD surface reactions. The ZrN film thickness determined from iSE data was found to be in agreement with the ex-situ XRR measurement. The metallic nature of ZrN films deposited with 0.10s TDMAZr – 12s purge – 9s plasma – 9s purge at 150 °C and 600 Watts plasma was concluded from the free electron dispersion component of the dielectric function and photoemission features at the Fermi level in the valence band XPS spectra. The glancing incidence x-ray diffraction (GIXRD) pattern was consistent with ZrN and Zr3N4 phases along with ZrO2 feature arising from the post-deposition surface oxidation. The electrical resistivity for 35.5 nm ZrN film was found to be 559.5 μΩ-cm. The XPS survey spectra showed presence of O and C within the grown ZrN film. The relatively high concentrations of O was explained on the basis of high energy Ar+ sputtering induced diffusion of oxygen atoms from the surface oxide layer into the underlying film. To address poor ALD precursor consumption, a first-principle numerical model for ALD growth was developed to compare novel ALD recipes with the conventional ABAB… type deposition. ZrN PEALD with AABAAB... cycle showed ~20% increase in the GPC along with 50% reduction in the TDMAZr dose for saturation as compared to ABAB… cycle under similar process conditions.

• Subjects / Keywords

  • Spectroscopic Ellipsometry
  • Atomic Layer Deposition
  • ALD Process Optimization
  • Conducting Zirconium Nitride Growth

• Graduation date

  Spring 2015

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/R3XS5JV6S

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.