Deposition of Pr- and Nd-aluminate by liquid injection MOCVD and ALD using single-source heterometallic alkoxide precursors

Thin films of praseodymium aluminate (PrAlO chi) and neodymium aluminate (NdAlO chi) have been deposited by liquid injection metalorganic chemical vapor deposition (MOCVD) and atomic layer deposition (ALD) using the bimetallic alkoxide precursors [PrAl(OPri)(6)((PrOH)-O-i)](2) and [NdAl(OPri)(6)((PrOH)-O-i)](2). Auger electron spectroscopy showed that all the films were high purity, with no carbon detectable (est. detection limit approximate to 0.5 at %). X-ray diffraction showed that the PrAlO chi and NdAlO chi films remained amorphous up to temperatures of 900 degrees 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 chi (Pr/Al = 0.76) and NdAlO chi (Nd/Al = 0.87) were obtained by MOCVD at deposition temperatures of 500 and 450 degrees 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 chi were superior to those of PrAlO chi. MOSCs fabricated with NdAl chi O gamma (Nd/Al = 0.87) and PrAlO chi (Pr/Al 0.76) showed leakage current densities below 7.5 x 10(-10) A cm(-2) (K similar to 14) and 1 x 10(-6) A cm(-2) (K approximate to 12), respectively.