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

• Published in: Journal of vacuum science & technology. A, Vacuum, surfaces, and films Vacuum, surfaces, and films, 2005-07, Vol.23 (4), p.1238-1243
• Main Authors: Yang, Taek Seung, Cho, Wontae, Kim, Minchan, An, Ki-Seok, Chung, Taek-Mo, Kim, Chang Gyoun, Kim, Yunsoo
• Format: Article
• Language: English
• ISSN: 0734-2101; 1520-8559
• DOI: 10.1116/1.1875172

A precursor originally synthesized for the chemical vapor deposition of metallic nickel, Ni ( dmamp ) 2 ( dmamp = 1-dimethylamino-2-methyl-2-propanolate, - OC Me 2 C H 2 N Me 2 ), has been adopted as a nickel source for the atomic layer deposition of nickel oxide (NiO) using water ( H 2 O ) as the oxygen source. The precursor is a solid at room temperature, but readily sublimes at 90 °C. The self-limiting atomic layer deposition (ALD) process by alternate surface reactions of Ni ( dmamp ) 2 and H 2 O was confirmed from thickness measurements of the NiO films grown with varying Ni ( dmamp ) 2 supply times and numbers of the Ni ( dmamp ) 2 - H 2 O ALD cycles. The ALD temperature window for this precursor was found to be between 90 and 150 °C. Under optimal reaction conditions, the growth rate of the NiO films was ∼ 0.8 Å ∕ cycle . The NiO films deposited on Si(001) at 120 °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 Å (with 1000 ALD cycles) the root-mean-square surface roughness was only ∼ 4 Å as measured by atomic force microscopy. To elucidate the ALD mechanism of the Ni precursor with water, a quadrupole mass analyzer was employed with D 2 O as the oxygen source in lieu of H 2 O . 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.