Spectroscopic Investigation of Hf-Si Oxynitride Alloys and Low Temperature Cobalt Metal ALD

Sang Jeong Oh
Abstract & Cover

Hf-Si oxynitride alloys were deposited by a remote plasma-enhanced chemical vapor deposition (RPECVD) system using the combination of the process conditions for Si oxynitride and Hf silicate alloys. The N-KLL, O-KLL, and Hf-NVV intensities measured by on-line AES (Auger Electron Spectroscopy) spectra were used to calculate the composition of alloys. The composition of Hf-Si oxynitride alloys can be tuned by controlling the N2 / (N2 + N2O) ratio, Hf source flow rate, and the amount of He dilution. FTIR (Fourier Transform Infrared Spectroscopy) and XPS (X-ray Photoelectron Spectroscopy) measurements were performed off-line and the results were used to investigate changes in film internal structure with (i) composition, and (ii) post-deposition annealing temperature. As deposited alloys show single feature in FTIR spectra, and there is no evidence of metallic Hf-Si, Hf-N, Hf-Hf, or Si-Si bonding in XPS core-level spectra. The (HfO2)X(SiO2)1-X alloys and (Si3N4)x(SiO2)0.5•(1-x)(HfO2)0.5•(1-x) alloys with low Si3N4 concentration (x = 0.07 and 0.17) show changes in FTIR absorption spectra after anneal at 900 ~ 1100 60s ℃ , in Ar. However, (Si3N4)x(SiO2)0.5•(1-x)(HfO2)0.5•(1-x) alloys with high Si3N4 concentration (x = 0.33 and 0.49) show no change in FTIR spectra even after 1100 anneal. ℃ The results of XPS O1s spectra of the pseudo-binary (HfO2)X(SiO2)1-X alloys and the pseudo-ternary (Si3N4)x(SiO2)0.5•(1-x)(HfO2)0.5•(1-x) alloys correspond to the results of FTIR spectra. The chemical phase separation in Hf-Si oxynitride alloys was suppressed when the amount of Si3N4 phase is above 33%. Micro/nanotubes with precisely defined nanoscale walls have attracted considerable attention with a variety of different processes and materials. Since ALD provides excellent step coverage on aggressive topographic structures, ALD has expanded rapidly its application fields. In some cases, ALD can be conducted at the generally lower temperature (~100℃ or less). This makes ALD attractive for coating on temperature-sensitive materials. We explored the low temperature metal ALD process for the fabrication of nanostructures. In this work, Cobalt thin film deposition using atomic layer deposition process sequencing was studied between 30 and 130°C using Co2(CO)8 and H2 gases using on-line quadrupole mass spectrometry and Auger electron spectroscopy. Similar experiments using cobalt cyclopentadienyl dicarbonyl and H2 reactants were also performed between 140 and 350°C. For the dicobalt octacarbonyl precursor, mass spectroscopy and growth rate analysis showed precursor dissociation with non-self-limiting adsorption leading to continuous film growth at temperatures as low as 60°C, whereas the cyclopentadienyl dicarbonyl precursor showed evidence for CO cleavage and volatile Co(cyclopentadienyl) resulting in no film growth until ~300°C. The continuous film growth with the Co2(CO)8 is related to the zero-valent metal center, where no reduction step is required to produce a reactive surface for adsorption. Evidence for Fisher-Tropsch catalytic production of CH4 is observed by mass spectroscopy during the initial cycles of Co film growth.

Source of Information
Gregory Parsons
North Carolina State University
(Raleigh, North Carolina, USA)
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