Atomic layer deposition of nickel oxide films using Ni(dmamp)2 and water

A precursor originally synthesized for the chemical vapor deposition of metallic nickel, Ni(dmamp)(2) (dmamp=1-dimethylamino-2-methyl-2-propanolate, -OCMe2CH2NMe2), has been adopted as a nickel source for the atomic layer deposition of nickel oxide (NiO) using water (H2O) as the oxygen source. The precursor is a solid at room temperature, but readily sublimes at 90 degrees C. The self-limiting atomic layer deposition (ALD) process by alternate surface reactions of Ni(dmamp)2 and H2O was confirmed from thickness measurements of the NiO films grown with varying Ni(dmaMP)(2) Supply times and numbers of the Ni(dmamp)(2)-H2O ALD cycles. The ALD temperature window for this precursor was found to be between 90 and 150 degrees C. Under optimal reaction conditions, the growth rate of the NiO films was similar to 0.8 angstrom/cycle. The NiO films deposited on Si(001) at 120 degrees C were characterized by x-ray diffraction, x-ray photoelectron spectroscopy, scanning electron microscopy, and atomic force microscopy. The x-ray diffraction patterns showed no distinct peaks for NiO, indicating that the films deposited at this temperature were amorphous. X-ray photoelectron spectroscopy analysis showed the films to be stoichiometric with no detectable amount of carbon impurities. For a film with the thickness of 810 A (with 1000 ALD cycles) the root-mean-square surface roughness was only similar to 4 angstrom as measured by atomic force microscopy. To elucidate the ALD mechanism of the Ni precursor with water, a quadrupole mass analyzer was employed with D2O as the oxygen source in lieu of H2O, Interestingly, unlike the usual ALD fashion, the Ni(dmamp)2 precursor does not seem to decompose but only coordinatively bond to the OH-terminated surface when it was introduced. Next, the Ni(dmamP)(2)-surface species decompose to produce a hydroxylated nickel oxide surface and the alcohol dmampH when water was supplied. (c) 2005 American Vacuum Society.