Deposition of Pr- and Nd-aluminate by Liquid Injection MOCVD and ALD Using Single-Source Heterometallic Alkoxide Precursors

• Published in: Chemistry of materials 2007-09, Vol.19 (19), p.4796-4803
• Main Authors: Gaskell, Jeffrey M, Przybylak, Szymon, Jones, Anthony C, Aspinall, Helen C, Chalker, Paul R, Black, Kate, Potter, Richard J, Taechakumput, Pouvanart, Taylor, Stephen
• Format: Article
• Language: English
• ISSN: 0897-4756; 1520-5002
• DOI: 10.1021/cm0707556

Thin films of praseodymium aluminate (PrAlO x ) and neodymium aluminate (NdAlO x ) have been deposited by liquid injection metalorganic chemical vapor deposition (MOCVD) and atomic layer deposition (ALD) using the bimetallic alkoxide precursors [PrAl(OPri)6(PriOH)]2 and [NdAl(OPri)6(PriOH)]2. Auger electron spectroscopy showed that all the films were high purity, with no carbon detectable (est. detection limit ≈ 0.5 at %). X-ray diffraction showed that the PrAlO x and NdAlO x films remained amorphous up to temperatures of 900 °C. Films grown by ALD were all Pr- or Nd-deficient (Pr/Al = 0.54−0.71; Nd/Al = 0.30−0.42), but near-stoichiometric films of PrAlO x (Pr/Al = 0.76) and NdAlO x (Nd/Al = 0.87) were obtained by MOCVD at deposition temperatures of 500 and 450 °C, respectively. The electrical properties of the films were assessed using C − V and I − V on MOS capacitors. Post-metalization annealing (PMA) in forming gas was effective in reducing charge levels in all films. Following PMA, the dielectric properties of NdAlO x were superior to those of PrAlOx, MOSCs fabricated with NdAl x O y (Nd/Al = 0.87) and PrAlO x (Pr/Al = 0.76) showed leakage current densities below 7.5 × 10-10 A cm-2 (κ ∼ 14) and 1 × 10-6 A cm-2 (κ ≈ 12), respectively.