Plasma-enhanced and thermal atomic layer deposition of Al{sub 2}O{sub 3} using dimethylaluminum isopropoxide, [Al(CH{sub 3}){sub 2}({mu}-O{sup i}Pr)]{sub 2}, as an alternative aluminum precursor
- Department of Applied Physics, Eindhoven University of Technology, P. O. Box 513, 5600 MB Eindhoven (Netherlands)
The authors have been investigating the use of [Al(CH{sub 3}){sub 2}({mu}-O{sup i}Pr)]{sub 2} (DMAI) as an alternative Al precursor to [Al(CH{sub 3}){sub 3}] (TMA) for remote plasma-enhanced and thermal ALD over wide temperature ranges of 25-400 and 100-400 deg. C, respectively. The growth per cycle (GPC) obtained using in situ spectroscopic ellipsometry for plasma-enhanced ALD was 0.7-0.9 A/cycle, generally lower than the >0.9 A/cycle afforded by TMA. In contrast, the thermal process gave a higher GPC than TMA above 250 deg. C, but below this temperature, the GPC decreased rapidly with decreasing temperature. Quadrupole mass spectrometry data confirmed that both CH{sub 4} and HO{sup i}Pr were formed during the DMAI dose for both the plasma-enhanced and thermal processes. CH{sub 4} and HO{sup i}Pr were also formed during the H{sub 2}O dose but combustion-like products (CO{sub 2} and H{sub 2}O) were observed during the O{sub 2} plasma dose. Rutherford backscattering spectrometry showed that, for temperatures >100 deg. C and >200 deg. C for plasma-enhanced and thermal ALD, respectively, films from DMAI had an O/Al ratio of 1.5-1.6, a H content of {approx}5 at. % and mass densities of 2.7-3.0 g cm{sup -3}. The film compositions afforded from DMAI were comparable to those from TMA at deposition temperatures {>=}150 deg. C At lower temperatures, there were differences in O, H, and C incorporation. 30 nm thick Al{sub 2}O{sub 3} films from the plasma-enhanced ALD of DMAI were found to passivate n- and p-type Si floatzone wafers ({approx}3.5 and {approx}2 {Omega} cm, respectively) with effective carrier lifetimes comparable to those obtained using TMA. Surface recombination velocities of < 3 and < 6 cm s{sup -1} were obtained for the n- and p-type Si, respectively. Using these results, the film properties obtained using DMAI and TMA are compared and the mechanisms for the plasma-enhanced and thermal ALD using DMAI are discussed.
- OSTI ID:
- 22054151
- Journal Information:
- Journal of Vacuum Science and Technology. A, International Journal Devoted to Vacuum, Surfaces, and Films, Vol. 30, Issue 2; Other Information: (c) 2012 American Vacuum Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 1553-1813
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
ALUMINIUM
ALUMINIUM OXIDES
CARBON
CARBON DIOXIDE
CARRIER LIFETIME
DENSITY
DEPOSITION
ELLIPSOMETRY
HYDROGEN
MASS SPECTROSCOPY
METHANE
OXYGEN
PLASMA
PRECURSOR
RECOMBINATION
RUTHERFORD BACKSCATTERING SPECTROSCOPY
THIN FILMS
WATER